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fines migration behavior can either promote or obstruct fluid flow within the reservoir and is crucial for productivity optimization that needs fundamental understanding. the present work focuses on the contributions from effective stress build - up due to reservoir depletion and decreases in brine salinity from low - salinity water injection. particle detachment is studied analytically by using the critical retention concentration function modified with stress and salinity dependents. increase in formation effective stress leads to deformations within the reservoir configurations due to micro - cracks and reduced pore dimensions. decreased size of the travelling channels promotes particle detachment, while the critical retention concentration decreases. a sensitivity study reveals that, under influence of effective stress, particle size and fluid velocity are dominant parameters controlling the fines migration by influencing the particle detaching forces. with decreasing brine salinity ( e. g. via low - salinity water injection ), clay particles that are attached on the pore surface increasingly swell, leading to reduction in effective pore space and flow channel. decreased pore space directly obstructs travelling of suspended particles and fluids which results in permeability decline. initial clay particle size is found to be a critical factor controlling particle detachment behavior. small initial particle sizes are not likely to detach from the pore surface as a result of weak detaching forces, hence the analysis finds the critical retention concentration unchanged resulting in negligible permeability decline as a function of brine salinity. considering both effects, effective stress and brine salinity, stress - dependent effects dominate salinity - dependent effects at low effective stress while the two contribute equally at high effective stress.
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arxiv:2006.13306
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recently, a number of statistical problems have found an unexpected solution by inspecting them through a " modal point of view ". these include classical tasks such as clustering or regression. this has led to a renewed interest in estimation and inference for the mode. this paper offers an extensive survey of the traditional approaches to mode estimation and explores the consequences of applying this modern modal methodology to other, seemingly unrelated, fields.
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arxiv:1807.02789
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the angular - momentum linear inverted pendulum ( alip ) model is a promising motion planner for bipedal robots. however, it relies on two assumptions : ( 1 ) the robot has point - contact feet or passive ankles, and ( 2 ) the angular momentum around the center of mass, known as centroidal angular momentum, is negligible. this paper addresses the question of whether the alip paradigm can be applied to more general bipedal systems with complex foot geometry ( e. g., flat feet ) and nontrivial torso / limb inertia and mass distribution ( e. g., non - centralized arms ). in such systems, the dynamics introduce non - negligible centroidal momentum and contact wrenches at the feet, rendering the assumptions of the alip model invalid. this paper presents the alip planner for general bipedal robots with non - point - contact feet through the use of a task - space whole - body controller that regulates centroidal momentum, thereby ensuring that the robot ' s behavior aligns with the desired template dynamics. to demonstrate the effectiveness of our proposed approach, we conduct simulations using the sarcos guardian xo robot, which is a hybrid humanoid / exoskeleton with large, offset feet. the results demonstrate the practicality and effectiveness of our approach in achieving stable and versatile bipedal locomotion.
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arxiv:2408.05308
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the active galactic nucleus 4c + 28. 07 is a flat spectrum radio quasar, one of the brightest at $ \ gamma $ - ray energies. we study its multi - wavelength emission by analysing $ \ sim12. 3 $ years of \ textit { fermi - lat } data in the $ \ gamma $ - ray band and \ textit { swift - xrt / uvot } available data in x - ray and optical - to - ultraviolet bands. in the $ \ gamma $ - ray band, five flaring periods have been detected, during which the flux dramatically increases by several times ( > 5 ) compared with its average quiescent phase. quasi - simultaneously with the flaring times, the x - ray and uvot data detected by \ textit { swift - xrt / uvot } have also been analysed. in one of the brightest flare periods ( flare 5 ; observed on oct 12, 2018 ) the $ \ gamma $ - ray flux reached $ ( 6. 7 \ pm0. 81 ) \ times 10 ^ { - 6 } $ photon / cm ^ 2 / s ( $ \ sim31 \ times $ higher than the mean flux over 12. 3 years ) with detection significance of $ \ sigma = 6. 1 $. the apparent $ \ gamma $ - ray luminosity of this flaring corresponds to $ 3. 6 \ times10 ^ { 49 } $ erg / s ( for a distance of 8. 38 gpc ), one of the highest $ \ gamma $ - ray luminosities observed for blazars. flare 5 has an estimated $ \ sim2 $ hours time block, which can be considered the average $ \ gamma $ - ray variability time. the variability time constrains the $ \ gamma $ - ray emitting region size to < 9e14 cm, which is close to the black hole radius. the spectral energy distributions ( seds ) in the $ \ gamma $ - ray band for the $ \ sim12. 3 $ years of data show an early cut - off at $ \ sim14 $ gev ; beyond $ \ sim60 $ gev, however, the spectrum hardens and is detected up to $ \ sim316 $ gev. similar spectral behaviour is also noticeable for the seds of flares, which can be linked to the photon absorption by the emitting region ' s internal and external narrow - band radiation fields. considering the significance of the obtained results from 4c
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arxiv:2109.08752
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this study examines the limitations of h $ \ alpha $ luminosity as a tracer of star formation rates ( sfr ) in spatially resolved observations. we carry out high - resolution simulations of a milky way - like galaxy including both supernova and photoionization feedback, and from these we generate synthetic h $ \ alpha $ emission maps that we compare to maps of the true distribution of young stellar objects ( ysos ) on scales from whole - galaxy to individual molecular clouds ( $ \ lesssim 100 $ pc ). our results reveal significant spatial mismatches between h $ \ alpha $ and true yso maps on sub - 100 pc scales, primarily due to ionizing photon leakage, with a secondary contribution from young stars drifting away from their parent molecular clouds. on small scales these effect contribute significantly to the observed anti - correlation between gas and star formation, such that there is noticeably less anti - correlation if we replace an h $ \ alpha $ - based star formation map with a yso - based one ; this in turn implies that previous studies have underestimated the time it takes for young stars to disperse their parent molecular clouds. however, these effects are limited in dense regions with hydrogen columns $ n _ \ mathrm { h } > 3 \ times 10 ^ { 21 } $ cm $ ^ { - 2 } $, where the h $ \ alpha $ - and yso - based sfr maps show better agreement. based on this finding we propose a calibration model that can precisely measure the sfr of large molecular clouds ( mean radius > 100 pc ) with a combination of h $ \ alpha $ and co observations, which provides a foundation for future study of star formation processes in extragalactic molecular clouds.
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arxiv:2406.11155
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large - $ n $ galaxy surveys offer unprecedented opportunities to probe weak gravitation in galaxy dynamics that may contain correlations tracing background cosmology. of particular interest is the potential of finite sensitivities to the background de sitter scale of acceleration $ a _ { ds } = ch $, where $ h $ is the hubble parameter and $ c $ is the velocity of light. at sufficiently large $ n $, this is possibly probed by ensemble - averaged ( " stacked " ) rotation curves ( rcs ) at resolutions on par with present estimates of the hubble parameter $ h _ 0 $. here, we consider the prospect for studies using the large $ n $ mapping nearby galaxies at apache point observatory ( manga ) at apo survey. in a first and preliminary step, we consider unbiased control of sub - sample size by consistency in the three position angles, $ \ theta $, from photometry and velocity fields of gas and stars by spectroscopy within $ 30 ^ \ circ $. in sub - samples of size $ n = n _ i ( \ theta ) $, the scatter in - the - mean $ \ sigma / \ sqrt { n } $ is found to reach one percent levels, differentiated over inclination angle $ i $ and $ \ theta $. in regular propagation of uncertainties, this scatter contributes $ \ kappa \ sigma / \ sqrt { n } $ to the standard error in - the - mean to the observable, where $ \ kappa $ is determined by the choice of observables. as a lower bound to scatter in stacked rcs, manga hereby appears promising for high - resolution analysis of sensitivity to rcs to background cosmology, notably across a sharp $ c ^ 0 $ - transition ( van putten 2018 ) of newtonian to anomalous dynamics across $ a _ { ds } $ and, further out, the baryonic tully - fisher relation. in turn, these markers provide a novel measurement of cosmological parameters.
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arxiv:2501.11882
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the discovery of autonomous systems ( ases ) interconnections and the inference of their commercial type - of - relationships ( tor ) has been extensively studied during the last few years. the main motivation is to accurately calculate as - level paths and to provide better topological view of the internet. an inherent problem in current algorithms is their extensive use of heuristics. such heuristics incur unbounded errors which are spread over all inferred relationships. we propose a near - deterministic algorithm for solving the tor inference problem. our algorithm uses as input the internet core, which is a dense sub - graph of top - level ases. we test several methods for creating such a core and demonstrate the robustness of the algorithm to the core ' s size and density, the inference period, and errors in the core. we evaluate our algorithm using as - level paths collected from routeviews bgp paths and dimes traceroute measurements. our proposed algorithm deterministically infers over 95 % of the approximately 58, 000 as topology links. the inference becomes stable when using a week worth of data and as little as 20 ases in the core. the algorithm infers 2 - 3 times more peer - to - peer relationships in edges discovered only by dimes than in routeviews edges, validating the dimes promise to discover periphery as edges.
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arxiv:0711.4562
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accurate bot detection is necessary for the safety and integrity of online platforms. it is also crucial for research on the influence of bots in elections, the spread of misinformation, and financial market manipulation. platforms deploy infrastructure to flag or remove automated accounts, but their tools and data are not publicly available. thus, the public must rely on third - party bot detection. these tools employ machine learning and often achieve near perfect performance for classification on existing datasets, suggesting bot detection is accurate, reliable and fit for use in downstream applications. we provide evidence that this is not the case and show that high performance is attributable to limitations in dataset collection and labeling rather than sophistication of the tools. specifically, we show that simple decision rules - - shallow decision trees trained on a small number of features - - achieve near - state - of - the - art performance on most available datasets and that bot detection datasets, even when combined together, do not generalize well to out - of - sample datasets. our findings reveal that predictions are highly dependent on each dataset ' s collection and labeling procedures rather than fundamental differences between bots and humans. these results have important implications for both transparency in sampling and labeling procedures and potential biases in research using existing bot detection tools for pre - processing.
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arxiv:2301.07015
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the human brain is a complex dynamical system which displays a wide range of macroscopic and mesoscopic patterns of neural activity, whose mechanistic origin remains poorly understood. whole - brain modelling allows us to explore candidate mechanisms causing the observed patterns. however, it is not fully established how the choice of model type and the networks ' resolution influence the simulation results, hence, it remains unclear, to which extent conclusions drawn from these results are limited by modelling artefacts. here, we compare the dynamics of a biophysically realistic, linear - nonlinear cascade model of whole - brain activity with a phenomenological wilson - cowan model using three structural connectomes based on the schaefer parcellation scheme with 100, 200, and 500 nodes. both neural mass models implement the same mechanistic hypotheses, which specifically address the interaction between excitation, inhibition, and a slow adaptation current, which affects the excitatory populations. we quantify the emerging dynamical states in detail and investigate how consistent results are across the different model variants. then we apply both model types to the specific phenomenon of slow oscillations, which are a prevalent brain rhythm during deep sleep. we investigate the consistency of model predictions when exploring specific mechanistic hypotheses about the effects of both short - and long - range connections and of the antero - posterior structural connectivity gradient on key properties of these oscillations. overall, our results demonstrate that the coarse - grained dynamics are robust to changes in both model type and network resolution. in some cases, however, model predictions do not generalize. thus, some care must be taken when interpreting model results.
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arxiv:2504.17491
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we investigate qualitative and quantitative behavior of a solution of the mathematical model for pricing american style of perpetual put options. we assume the option price is a solution to the stationary generalized black - scholes equation in which the volatility function may depend on the second derivative of the option price itself. we prove existence and uniqueness of a solution to the free boundary problem. we derive a single implicit equation for the free boundary position and the closed form formula for the option price. it is a generalization of the well - known explicit closed form solution derived by merton for the case of a constant volatility. we also present results of numerical computations of the free boundary position, option price and their dependence on model parameters.
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arxiv:1611.00885
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analytical calculations based on a landau level ( ll ) picture are reported for an interface ( with a finite - width quantum well ( qw ) ) and for a fully three - dimensional charged quantum electronic system in an external magnetic field. they lead to a sequence of previously unnoticed singular features in global magnetization and magnetic susceptibility that lead to nontrivial corrections to the standard de haas - van alphen periods. additional features due to zeeman splitting are also reported ( such as new energy minima that originate from the interplay of qw, zeeman and ll physics ) that are possibly useful for the design of quantum devices. a corresponding calculation in a composite fermion picture leads to new predictions on magnetic response properties of a fully - interacting electron liquid in a finite - width interface.
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arxiv:1009.1390
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identifying the best arm of a multi - armed bandit is a central problem in bandit optimization. we study a quantum computational version of this problem with coherent oracle access to states encoding the reward probabilities of each arm as quantum amplitudes. specifically, we show that we can find the best arm with fixed confidence using $ \ tilde { o } \ bigl ( \ sqrt { \ sum _ { i = 2 } ^ n \ delta ^ { \ smash { - 2 } } _ i } \ bigr ) $ quantum queries, where $ \ delta _ { i } $ represents the difference between the mean reward of the best arm and the $ i ^ \ text { th } $ - best arm. this algorithm, based on variable - time amplitude amplification and estimation, gives a quadratic speedup compared to the best possible classical result. we also prove a matching quantum lower bound ( up to poly - logarithmic factors ).
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arxiv:2007.07049
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in this paper we present a service injection and composition design pattern for unstructured peer - to - peer networks, which is designed with aspect - oriented design patterns, and amalgamation of the strategy, worker object, and check - list design patterns used to design the self - adaptive systems. it will apply self reconfiguration planes dynamically without the interruption or intervention of the administrator for handling service failures at the servers. when a client requests for a complex service, service composition should be done to fulfil the request. if a service is not available in the memory, it will be injected as aspectual feature module code. we used service oriented architecture ( soa ) with web services in java to implement the composite design pattern. as far as we know, there are no studies on composition of design patterns for peer - to - peer computing domain. the pattern is described using a java - like notation for the classes and interfaces. a simple uml class and sequence diagrams are depicted.
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arxiv:1211.5227
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we present the josephson junction intersected superconducting transmission line resonator. in contrast to the josephson parametric amplifier, josephson bifurcation amplifier and josephson parametric converter we consider the regime of few microwave photons. we review the derivation of eigenmode frequencies and zero point fluctuations of the nonlinear transmission line resonator and the derivation of the eigenmode kerr nonlinearities. remarkably these nonlinearities can reach values comparable to transmon qubits rendering the device ideal for accessing the strongly correlated regime. this is particularly interesting for investigation of quantum many - body dynamics of interacting particles under the influence of drive and dissipation. we provide current profiles for the device modes and investigate the coupling between resonators in a network of nonlinear transmission line resonators.
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arxiv:1208.0134
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filamentary regions of high vorticity irregularly form and disappear in the turbulent flows of classical fluids. we report an experimental comparative study of these so - called " coherent structures " in a classical versus quantum fluid, using liquid helium with a superfluid fraction varied from 0 % up to 83 %. the low pressure core of the vorticity filaments is detected by pressure probes located on the sidewall of a 78 - cm - diameter von k \ ' arm \ ' an cell driven up to record turbulent intensity ( r $ \ lambda $ $ \ sim $ $ \ sqrt $ re 10000 ). the statistics of occurrence, magnitude and relative distribution of the filaments in a classical fluid are found indistinguishable from their superfluid counterpart, namely the bundles of quantized vortex lines. this suggest that the internal structure of vortex filaments, as well as their dissipative properties have a negligible impact on their macroscopic dynamics, such as lifetime and intermittent properties.
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arxiv:1705.10177
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gradient inversion attacks invert the transmitted gradients in federated learning ( fl ) systems to reconstruct the sensitive data of local clients and have raised considerable privacy concerns. a majority of gradient inversion methods rely heavily on explicit prior knowledge ( e. g., a well pre - trained generative model ), which is often unavailable in realistic scenarios. to alleviate this issue, researchers have proposed to leverage the implicit prior knowledge of an over - parameterized network. however, they only utilize a fixed neural architecture for all the attack settings. this would hinder the adaptive use of implicit architectural priors and consequently limit the generalizability. in this paper, we further exploit such implicit prior knowledge by proposing gradient inversion via neural architecture search ( gi - nas ), which adaptively searches the network and captures the implicit priors behind neural architectures. extensive experiments verify that our proposed gi - nas can achieve superior attack performance compared to state - of - the - art gradient inversion methods, even under more practical settings with high - resolution images, large - sized batches, and advanced defense strategies.
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arxiv:2405.20725
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we report the results of near - ir imaging in j and h, of i zw 36 ( $ \ approx $ z $ _ { \ odot } $ / 14 ) with the hubble space telescope. whereas imaging with the pre - costar faint object camera ( foc ) previously resolved hot and massive stars in the near - uv, the nicmos data furnish a census of the cool, intermediate - and low - mass stars. there clearly was star formation in i zw 36 prior to the activity which earned it its blue compact dwarf / wolf - rayet galaxy classification. the detection of luminous, asymptotic giant branch stars requires that stars formed vigorously several hundred myr ago. the well - populated red giant branch indicates stars with ages of at least 1 - 2 gyr ( and possibly older than 10 gyr ). we use the tip - of - the - red - giant - branch method to derive a distance of $ \ geq $ 5. 8 mpc. this is the third in a series of papers on near - ir - - - resolved blue compact dwarf galaxies. we notice that the color - magnitude diagrams of vii zw 403, mrk 178, and i zw 36 do not exhibit the gaps expected from an episodic mode of star formation. using simulated color - magnitude diagrams we demonstrate for i zw 36 that star formation did not stop for more than a few 10 $ ^ 8 $ yrs over the past 10 $ ^ 9 $ yrs, and discuss the implications of this result.
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arxiv:astro-ph/0102397
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we study distributed broadcasting protocols with few transmissions ( ` shots ' ) in radio networks where the topology is unknown. in particular, we examine the case in which a bound $ k $ is given and a node may transmit at most $ k $ times during the broadcasting protocol. initially, we focus on oblivious algorithms for $ k $ - shot broadcasting, that is, algorithms where each node decides whether to transmit or not with no consideration of the transmission history. our main contributions are ( a ) a lower bound of $ \ omega ( n ^ 2 / k ) $ on the broadcasting time of any oblivious $ k $ - shot broadcasting algorithm and ( b ) an oblivious broadcasting protocol that achieves a matching upper bound, namely $ o ( n ^ 2 / k ) $, for every $ k \ le \ sqrt { n } $ and an upper bound of $ o ( n ^ { 3 / 2 } ) $ for every $ k > \ sqrt { n } $. we also study the general case of adaptive broadcasting protocols where nodes decide whether to transmit based on all the available information, namely the transmission history known by each. we prove a lower bound of $ \ omega \ left ( n ^ { \ frac { 1 + k } { k } } \ right ) $ on the broadcasting time of any protocol by introducing the \ emph { transmission tree } construction which generalizes previous approaches.
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arxiv:1603.08393
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in this paper we study the problem of minimizing the average of a large number ( $ n $ ) of smooth convex loss functions. we propose a new method, s2gd ( semi - stochastic gradient descent ), which runs for one or several epochs in each of which a single full gradient and a random number of stochastic gradients is computed, following a geometric law. the total work needed for the method to output an $ \ varepsilon $ - accurate solution in expectation, measured in the number of passes over data, or equivalently, in units equivalent to the computation of a single gradient of the loss, is $ o ( ( \ kappa / n ) \ log ( 1 / \ varepsilon ) ) $, where $ \ kappa $ is the condition number. this is achieved by running the method for $ o ( \ log ( 1 / \ varepsilon ) ) $ epochs, with a single gradient evaluation and $ o ( \ kappa ) $ stochastic gradient evaluations in each. the svrg method of johnson and zhang arises as a special case. if our method is limited to a single epoch only, it needs to evaluate at most $ o ( ( \ kappa / \ varepsilon ) \ log ( 1 / \ varepsilon ) ) $ stochastic gradients. in contrast, svrg requires $ o ( \ kappa / \ varepsilon ^ 2 ) $ stochastic gradients. to illustrate our theoretical results, s2gd only needs the workload equivalent to about 2. 1 full gradient evaluations to find an $ 10 ^ { - 6 } $ - accurate solution for a problem with $ n = 10 ^ 9 $ and $ \ kappa = 10 ^ 3 $.
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arxiv:1312.1666
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the complete invariant for gradient like morse - smale dynamical systems ( vector fields and diffeomorphisms ) on closed 4 - manifolds are constructed. it is same as kirby diagram in a case of polar vector field without fixed points of index 3.
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arxiv:math/9904009
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question - answering systems have revolutionized information retrieval, but linguistic and cultural boundaries limit their widespread accessibility. this research endeavors to bridge the gap of the absence of efficient qna datasets in low - resource languages by translating the english question answering dataset ( squad ) using a robust data curation approach. we introduce mahasquad, the first - ever full squad dataset for the indic language marathi, consisting of 118, 516 training, 11, 873 validation, and 11, 803 test samples. we also present a gold test set of manually verified 500 examples. challenges in maintaining context and handling linguistic nuances are addressed, ensuring accurate translations. moreover, as a qna dataset cannot be simply converted into any low - resource language using translation, we need a robust method to map the answer translation to its span in the translated passage. hence, to address this challenge, we also present a generic approach for translating squad into any low - resource language. thus, we offer a scalable approach to bridge linguistic and cultural gaps present in low - resource languages, in the realm of question - answering systems. the datasets and models are shared publicly at https : / / github. com / l3cube - pune / marathinlp.
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arxiv:2404.13364
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we estimate the total dust input from the cool evolved stars in the small magellanic cloud ( smc ), using the 8 micron excess emission as a proxy for the dust - production rate. we find that asymptotic giant branch ( agb ) and red supergiant ( rsg ) stars produce ( 8. 6 - 9. 5 ) x 10 ^ 7 solar masses per year of dust, depending on the fraction of far - infrared sources that belong to the evolved star population ( with 10 % - 50 % uncertainty in individual dust - production rates ). rsgs contribute the least ( < 4 % ), while carbon - rich agb stars ( especially the so - called " extreme " agb stars ) account for 87 % - 89 % of the total dust input from cool evolved stars. we also estimate the dust input from hot stars and supernovae ( sne ), and find that if sne produce 10 ^ - 3 solar masses of dust each, then the total sn dust input and agb input are roughly equivalent. we consider several scenarios of sne dust production and destruction and find that the interstellar medium ( ism ) dust can be accounted for solely by stellar sources if all sne produce dust in the quantities seen around the dustiest examples and if most sne explode in dense regions where much of the ism dust is shielded from the shocks. we find that agb stars contribute only 2. 1 % of the ism dust. without a net positive contribution from sne to the dust budget, this suggests that dust must grow in the ism or be formed by another unknown mechanism.
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arxiv:1201.5384
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using a general effective lagrangian implementing the chiral symmetry breaking su ( 2 ) l x su ( 2 ) r - > su ( 2 ) { l + r }, we present a one - loop calculation of the oblique s and t parameters within electroweak strongly - coupled models with a light scalar. imposing a proper ultraviolet behaviour, we determine s and t at next - to - leading order in terms of a few resonance parameters. the constraints from the global fit to electroweak precision data force the massive vector and axial - vector states to be heavy, with masses above the tev scale, and suggest that the w + w - and zz couplings of the higgs - like scalar should be close to the standard model value. our findings are generic, since they only rely on soft requirements on the short - distance properties of the underlying strongly - coupled theory, which are widely satisfied in more specific scenarios.
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arxiv:1310.3121
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this work describes a methodology for producing high quality metallic surfaces from uranium primarily for characterisation and investigations involving electron backscatter diffraction. electrochemical measurements have been conducted to inform ideal polishing conditions to produce surfaces free from strain, induced by mechanical polishing. a commonly used solution for the electropolishing of uranium, consisting in part of phosphoric acid, was used to conduct the electrochemical experiments and polishing. x - ray diffraction techniques focusing on the surface show low stresses and strains are exhibited within the material. this is mirrored in good quality electron backscatter diffraction.
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arxiv:1803.05712
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the piaa is a now well demonstrated high contrast technique that uses an intermediate remapping of the pupil for high contrast coronagraphy ( apodization ), before restoring it to recover classical imaging capabilities. this paper presents the first demonstration of complete speckle control loop with one such piaa coronagraph. we show the presence of a complete set of remapping optics ( the so - called piaa and matching inverse piaa ) is transparent to the wavefront control algorithm. simple focal plane based wavefront control algorithms can thus be employed, without the need to model remapping effects. using the subaru coronagraphic extreme ao ( scexao ) instrument built for the subaru telescope, we show that a complete piaa - coronagraph is compatible with a simple implementation of a speckle nulling technique, and demonstrate the benefit of the piaa for high contrast imaging at small angular separation.
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arxiv:1206.2996
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we present a multi - wavelength characterisation of the planetary nebula ( pn ) ngc 6905 and its [ wolf - rayet ] - type ( [ wr ] ) central star ( cspn ) hd 193949. our nordic optical telescope ( not ) alhambra faint object spectrograph and camera ( alfosc ) spectra and images unveil in unprecedented detail the high - ionization structure of ngc 6905. the high - quality spectra of hd 193949 allowed us to detect more than 20 wr features including the characteristic o - bump, blue bump and red bump, which suggests a spectral type no later than a [ wo2 ] - subtype. moreover we detect the ne vii and ne viii broad emission lines, rendering hd 193949 yet another cspn with $ t _ \ mathrm { eff } \ lesssim150 $ kk exhibiting such stellar emission lines. we studied the physical properties ( $ t _ \ mathrm { e } $ and $ n _ \ mathrm { e } $ ) and chemical abundances of different regions within ngc 6905 including its low - ionization clumps ; abundances are found to be homogeneous. we used the powr stellar atmosphere code to model the spectrum of hd 193949, which is afterwards used in a photoionization model performed with cloudy that reproduces the nebular and dust properties for a total mass in the 0. 31 - 0. 47 m $ _ { \ odot } $ range and a mass of c - rich dust of $ \ sim $ 2 $ \ times10 ^ { - 3 } $ m $ _ { \ odot } $. adopting a current stellar mass of 0. 6 m $ _ { \ odot } $, our model suggests an initial mass $ \ sim $ 1 m $ _ \ odot $ for hd 193949, consistent with the observations.
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arxiv:2110.09551
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in recent years, machine learning has demonstrated impressive capability in handling molecular science tasks. to support various molecular properties at scale, machine learning models are trained in the multi - task learning paradigm. nevertheless, data of different molecular properties are often not aligned : some quantities, e. g. equilibrium structure, demand more cost to compute than others, e. g. energy, so their data are often generated by cheaper computational methods at the cost of lower accuracy, which cannot be directly overcome through multi - task learning. moreover, it is not straightforward to leverage abundant data of other tasks to benefit a particular task. to handle such data heterogeneity challenges, we exploit the specialty of molecular tasks that there are physical laws connecting them, and design consistency training approaches that allow different tasks to exchange information directly so as to improve one another. particularly, we demonstrate that the more accurate energy data can improve the accuracy of structure prediction. we also find that consistency training can directly leverage force and off - equilibrium structure data to improve structure prediction, demonstrating a broad capability for integrating heterogeneous data.
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arxiv:2410.10118
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we present a tripartite three - level state that allows a secret sharing protocol among the three parties, or a quantum key distribution protocol between any two parties. the state used in this scheme contains entanglement even after one system is traced out. we show how to utilize this residual entanglement for quantum key distribution purposes, and propose a realization of the scheme using entanglement of orbital angular momentum states of photons.
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arxiv:quant-ph/0412097
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combinatorial assembly uses standardized unit primitives to build objects that satisfy user specifications. this paper studies assembly sequence planning ( asp ) for physical combinatorial assembly. given the shape of the desired object, the goal is to find a sequence of actions for placing unit primitives to build the target object. in particular, we aim to ensure the planned assembly sequence is physically executable. however, asp for combinatorial assembly is particularly challenging due to its combinatorial nature. to address the challenge, we employ deep reinforcement learning to learn a construction policy for placing unit primitives sequentially to build the desired object. specifically, we design an online physics - aware action mask that filters out invalid actions, which effectively guides policy learning and ensures violation - free deployment. in the end, we apply the proposed method to lego assembly with more than 250 3d structures. the experiment results demonstrate that the proposed method plans physically valid assembly sequences to build all structures, achieving a $ 100 \ % $ success rate, whereas the best comparable baseline fails more than $ 40 $ structures. our implementation is available at \ url { https : / / github. com / intelligent - control - lab / physicsawarecombinatorialasp }.
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arxiv:2408.10162
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##omain of f, their composition is the function g ∘ f : x → z { \ displaystyle g \ circ f : x \ rightarrow z } defined by ( g ∘ f ) ( x ) = g ( f ( x ) ). { \ displaystyle ( g \ circ f ) ( x ) = g ( f ( x ) ). } that is, the value of g ∘ f { \ displaystyle g \ circ f } is obtained by first applying f to x to obtain y = f ( x ) and then applying g to the result y to obtain g ( y ) = g ( f ( x ) ). in this notation, the function that is applied first is always written on the right. the composition g ∘ f { \ displaystyle g \ circ f } is an operation on functions that is defined only if the codomain of the first function is the domain of the second one. even when both g ∘ f { \ displaystyle g \ circ f } and f ∘ g { \ displaystyle f \ circ g } satisfy these conditions, the composition is not necessarily commutative, that is, the functions g ∘ f { \ displaystyle g \ circ f } and f ∘ g { \ displaystyle f \ circ g } need not be equal, but may deliver different values for the same argument. for example, let f ( x ) = x2 and g ( x ) = x + 1, then g ( f ( x ) ) = x 2 + 1 { \ displaystyle g ( f ( x ) ) = x ^ { 2 } + 1 } and f ( g ( x ) ) = ( x + 1 ) 2 { \ displaystyle f ( g ( x ) ) = ( x + 1 ) ^ { 2 } } agree just for x = 0. { \ displaystyle x = 0. } the function composition is associative in the sense that, if one of ( h ∘ g ) ∘ f { \ displaystyle ( h \ circ g ) \ circ f } and h ∘ ( g ∘ f ) { \ displaystyle h \ circ ( g \ circ f ) } is defined, then the other is also defined, and they are equal, that is, ( h ∘ g ) ∘ f = h ∘ ( g ∘ f ). { \ displaystyle ( h \ circ g ) \ circ f = h \ circ ( g \ circ
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https://en.wikipedia.org/wiki/Function_(mathematics)
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the aim of this article is to provide an understanding of social networks as a useful addition to the standard tool - box of techniques used by system designers. to this end, we give examples of how data about social links have been collected and used in di erent application contexts. we develop a broad taxonomy - based overview of common properties of social networks, review how they might be used in di erent applications, and point out potential pitfalls where appropriate. we propose a framework, distinguishing between two main types of social network - based user selection - personalised user selection which identi es target users who may be relevant for a given source node, using the social network around the source as a context, and generic user selection or group delimitation, which lters for a set of users who satisfy a set of application requirements based on their social properties. using this framework, we survey applications of social networks in three typical kinds of application scenarios : recommender systems, content - sharing systems ( e. g., p2p or video streaming ), and systems which defend against users who abuse the system ( e. g., spam or sybil attacks ). in each case, we discuss potential directions for future research that involve using social network properties.
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arxiv:1707.05104
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we study daugavet - and $ \ delta $ - points in banach spaces. a norm one element $ x $ is a daugavet - point ( respectively a $ \ delta $ - point ) if in every slice of the unit ball ( respectively in every slice of the unit ball containing $ x $ ) you can find another element of distance as close to $ 2 $ from $ x $ as desired. in this paper we look for criteria and properties ensuring that a norm one element is not a daugavet - or $ \ delta $ - point. we show that asymptotically uniformly smooth spaces and reflexive asymptotically uniformly convex spaces do not contain $ \ delta $ - points. we also show that the same conclusion holds true for the james tree space as well as for its predual. finally we prove that there exists a superreflexive banach space with a daugavet - or $ \ delta $ - point provided there exists such a space satisfying a weaker condition.
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arxiv:2203.14528
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python testbed for federated learning algorithms ( ptb - fla ) is a simple fl framework targeting smart internet of things in edge systems that provides both generic centralized and decentralized fl algorithms, which implement the corresponding fl orchestration protocols that were formally verified using the process algebra csp. this approach is appropriate for systems with stationary nodes but cannot be applied to systems with moving nodes. in this paper, we use celestial mechanics to model spacecraft movement, and timed automata ( ta ) to formalize and verify the centralized fl orchestration protocol, in two phases. in the first phase, we created a conventional ta model to prove traditional properties, namely deadlock freeness and termination. in the second phase, we created a stochastic ta model to prove timing correctness and to estimate termination probability.
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arxiv:2410.13429
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purpose : to assess the peripheral refraction induced by fractal contact lenses ( fcls ) in myopic eyes by means of a two - dimensional relative peripheral refractive error ( rpre ) map. methods : fcls prototypes were specially manufactured and characterized. this study involved twenty - six myopic subjects ranging from - 0. 50 d to - 7. 00 d. the two - dimensional rpre was measured with an open - field autorefractor by means of tracking targets distributed in a square grid from - 30 degrees ( deg ) nasal to 30 deg temporal and 15 deg superior to - 15 deg inferior. corneal topographies were taken in order to assess correlations between corneal asphericity, lens decentration and rpre represented in vector components m, j0 and j45. results : the mean power of the fcls therapeutic zones was 1. 32 + / - 0. 28 d. significant correlations were found between the corneal asphericity and vector components of the rpre in the nacked eyes. fcls were decentered a mean of 0. 7 + / - 0. 19 mm to the temporal cornea. m decreased asymmetrically between nasal and temporal retina after fitting the fcls with a significant increment of the myopic shift besides 10 deg ( p < 0. 05 ) and the induced myopic shift at 25 deg and 30 deg decreased with fcls decentration to temporal cornea. the peak of maximum myopic shift at the peripheral retina ( m = - 1. 3 d ) was located at 20 deg. two - dimensional maps showed uniform significant differences in extreme positions of the visual field in comparison with the horizontal rpre for m and j0, but not for j45. conclusions : fcls measured in myopic eyes showed a similar performance than the reported in previous ray - tracing studies with a small bias explained by the manufacturing process and the lens decentration. two - dimensional maps are preferable for assessing j45 changes due to the lens.
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arxiv:1609.06987
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equational theories that contain axioms expressing associativity and commutativity ( ac ) of certain operators are ubiquitous. theorem proving methods in such theories rely on well - founded orders that are compatible with the ac axioms. in this paper we consider various definitions of ac - compatible knuth - bendix orders. the orders of steinbach and of korovin and voronkov are revisited. the former is enhanced to a more powerful version, and we modify the latter to amend its lack of monotonicity on non - ground terms. we further present new complexity results. an extension reflecting the recent proposal of subterm coefficients in standard knuth - bendix orders is also given. the various orders are compared on problems in termination and completion.
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arxiv:1403.0406
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we prove that the brauer - manin obstruction is the only obstruction to the hasse principle and to the weak approximation for zero - cycles on certain fibrations over a smooth curve or over the projective space. the principal novelty is that the arithmetic hypotheses are supposed only on the fibres over a generalized hilbertian subset.
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arxiv:1104.0204
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qed radiative corrections to the cross section of diffractive electro - and photoproduction of vector mesons is calculated at hera energies. both semi - analytical and monte carlo approaches are discussed and compared.
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arxiv:hep-ph/9906410
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uncertainty propagation in nonlinear dynamic systems remains an outstanding problem in scientific computing and control. numerous approaches have been developed, but are limited in their capability to tackle problems with more than a few uncertain variables or require large amounts of simulation data. in this paper, we propose a data - driven method for approximating joint probability density functions ( pdfs ) of nonlinear dynamic systems with initial condition and parameter uncertainty. our approach leverages on the power of deep learning to deal with high - dimensional inputs, but we overcome the need for huge quantities of training data by encoding pdf evolution equations directly into the optimization problem. we demonstrate the potential of the proposed method by applying it to evaluate the robustness of a feedback controller for a six - dimensional rigid body with parameter uncertainty.
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arxiv:1911.09311
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we present the detection and analysis of grb 231115a, a candidate extragalactic magnetar giant flare ( mgf ) observed by fermi / gbm and localized by integral to the starburst galaxy m82. this burst exhibits distinctive temporal and spectral characteristics that align with known mgfs, including a short duration and a high peak energy. gamma - ray analyses reveal significant insights into this burst, supporting conclusions already established in the literature : our time - resolved spectral studies provide further evidence that grb 231115a is indeed a mgf. significance calculations also suggest a robust association with m82, further supported by a high bayes factor that minimizes the probability of chance alignment with a neutron star merger. despite extensive follow - up efforts, no contemporaneous gravitational wave or radio emissions were detected. the lack of radio emission sets stringent upper limits on possible radio luminosity. constraints from our analysis show no fast radio bursts ( frbs ) associated with two mgfs. x - ray observations conducted post - burst by swift / xrt and xmm / newton provided additional data, though no persistent counterparts were identified. our study underscores the importance of coordinated multi - wavelength follow - up and highlights the potential of mgfs to enhance our understanding of short grbs and magnetar activities in the cosmos. current mgf identification and follow - up implementation are insufficient for detecting expected counterparts ; however, improvements in these areas may allow for the recovery of follow - up signals with existing instruments. future advancements in observational technologies and methodologies will be crucial in furthering these studies.
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arxiv:2409.06056
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the paper establishes a sharp and rigid isoperimetric - type inequality in lorentzian signature under the assumption of ricci curvature bounded below in the timelike directions. the inequality is proved in the high generality of lorentzian pre - length spaces satisfying timelike ricci lower bounds in a synthetic sense via optimal transport, the so - called $ \ mathsf { tcd } ^ e _ p ( k, n ) $ spaces. the results are new already for smooth lorentzian manifolds. applications include an upper bound on the area of achronal hypersurfaces inside the interior of a black hole ( original already in schwarzschild ) and an upper bound on the area of achronal hypersurfaces in cosmological spacetimes.
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arxiv:2401.03949
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a kinetic one - dimensional ising model is coupled to two heat baths, such that spins at even ( odd ) lattice sites experience a temperature $ t _ { e } $ ( $ % t _ { o } $ ). spin flips occur with glauber - type rates generalised to the case of two temperatures. driven by the temperature differential, the spin chain settles into a non - equilibrium steady state which corresponds to the stationary solution of a master equation. we construct a perturbation expansion of this master equation in terms of the temperature difference and compute explicitly the first two corrections to the equilibrium boltzmann distribution. the key result is the emergence of additional spin operators in the steady state, increasing in spatial range and order of spin products. we comment on the violation of detailed balance and entropy production in the steady state.
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arxiv:cond-mat/0206345
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a pair of graphs $ ( \ gamma, \ sigma ) $ is said to be stable if the full automorphism group of $ \ gamma \ times \ sigma $ is isomorphic to the product of the full automorphism groups of $ \ gamma $ and $ \ sigma $ and unstable otherwise, where $ \ gamma \ times \ sigma $ is the direct product of $ \ gamma $ and $ \ sigma $. in this paper, we reduce the study of the stability of any pair of regular graphs $ ( \ gamma, \ sigma ) $ with coprime valencies and vertex - transitive $ \ sigma $ to that of $ ( \ gamma, k _ 2 ) $. since the latter is well studied in the literature, this enables us to determine the stability of any pair of regular graphs $ ( \ gamma, \ sigma ) $ with coprime valencies in the case when $ \ sigma $ is vertex - transitve and the stability of $ ( \ gamma, k _ 2 ) $ is known.
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arxiv:2210.06777
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we present the integrated 3 - point shear correlation function $ i \ zeta _ { \ pm } $ - - a higher - order statistic of the cosmic shear field - - which can be directly estimated in wide - area weak lensing surveys without measuring the full 3 - point shear correlation function, making this a practical and complementary tool to 2 - point statistics for weak lensing cosmology. we define it as the 1 - point aperture mass statistic $ m _ { \ mathrm { ap } } $ measured at different locations on the shear field correlated with the corresponding local 2 - point shear correlation function $ \ xi _ { \ pm } $. building upon existing work on the integrated bispectrum of the weak lensing convergence field, we present a theoretical framework for computing the integrated 3 - point function in real space for any projected field within the flat - sky approximation and apply it to cosmic shear. using analytical formulae for the non - linear matter power spectrum and bispectrum, we model $ i \ zeta _ { \ pm } $ and validate it on n - body simulations within the uncertainties expected from the sixth year cosmic shear data of the dark energy survey. we also explore the fisher information content of $ i \ zeta _ { \ pm } $ and perform a joint analysis with $ \ xi _ { \ pm } $ for two tomographic source redshift bins with realistic shape - noise to analyse its power in constraining cosmological parameters. we find that the joint analysis of $ \ xi _ { \ pm } $ and $ i \ zeta _ { \ pm } $ has the potential to considerably improve parameter constraints from $ \ xi _ { \ pm } $ alone, and can be particularly useful in improving the figure of merit of the dynamical dark energy equation of state parameters from cosmic shear data.
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arxiv:2102.10177
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for a normalized newform $ g \ in s _ { k } ( \ gamma _ { 0 } ( n ) ) $ with complex multiplication by an imaginary quadratic field $ k $, there is a mock modular form $ f ^ { + } $ corresponding to $ g $. k. bringmann et al. modified $ f ^ { + } $ in order to obtain a $ p $ - adic modular form by a certain $ p $ - adic constant $ \ alpha _ { g } $. in addition, they showed that if $ p $ is split in $ \ mathcal { o } _ { k } $ and $ p \ nmid n $, then $ \ alpha _ { g } = 0 $. on the other hand, the author showed that $ \ alpha _ { g } $ is a $ p $ - adic unit for an inert prime $ p $ satisfying that $ p \ nmid 2n $ when $ \ dim _ { \ mathbb { c } } s _ { k } ( \ gamma _ { 0 } ( n ) ) = 1 $. in this paper, under mild condition, we determine the $ p $ - adic valuation of $ \ alpha _ { g } $ for an inert prime $ p $ and a general cm form $ g $ of weight $ 2 $ with rational fourier coefficients.
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arxiv:2412.12811
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theta 1 ori e is a young, moderate mass binary system, a rarely observed case of spectral - type g - giants of about 3 solar masses, which are still collapsing towards the main sequence. we have obtained high resolution x - ray spectra with chandra and find that the system is very active and similar to coronal sources, having emission typical of magnetically confined plasma : a broad temperature distribution with a hot component and significant high energy continuum ; narrow emission lines from h - and he - like ions, as well as a range of fe ions, and relative luminosity, l _ x / l _ bol = 0. 001. density, while poorly constrained, is consistent with the low density limits as determined from mg xi and ne ix emission lines. coronal elemental abundances are sub - solar, with ne being the highest at about 0. 4 times solar. we find a possible trend in trapezium hot plasmas towards low relative abundances of fe, o, and ne, which is hard to explain in terms of the dust depletion scenarios of low - mass young stars. variability was unusually low relative to other coronally active stars. the emission is similar to post main - sequence g - stars. coronal structures could be compact or comparable to the dimensions of the stellar radii. we conclude that the x - rays in theta 1 ori e are generated by a convective dynamo.
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arxiv:0911.0189
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given a numerical semigroup ring $ r = k [ \! [ s ] \! ] $, an ideal $ e $ of $ s $ and an odd element $ b \ in s $, the numerical duplication $ s \! \ join ^ b \! e $ is a numerical semigroup, whose associated ring $ k [ \! [ s \! \ join ^ b \! e ] \! ] $ shares many properties with the nagata ' s idealization and the amalgamated duplication of $ r $ along the monomial ideal $ i = ( t ^ e \ mid e \ in e ) $. in this paper we study the associated graded ring of the numerical duplication characterizing when it is cohen - macaulay, gorenstein or complete intersection. we also study when it is a homogeneous numerical semigroup, a property that is related to the fact that a ring has the same betti numbers of its associated graded ring. on the way we also characterize when $ { \ rm gr } _ { \ mathfrak m } ( i ) $ is cohen - macaulay and when $ { \ rm gr } _ { \ mathfrak m } ( \ omega _ r ) $ is a canonical module of $ { \ rm gr } _ { \ mathfrak m } ( r ) $ in terms of numerical semigroup ' s properties, where $ \ omega _ r $ is a canonical module of $ r $.
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arxiv:1803.08302
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we propose a dynamic network quantile regression model to investigate the quantile connectedness using a predetermined network information. we extend the existing network quantile autoregression model of zhu et al. ( 2019b ) by explicitly allowing the contemporaneous network effects and controlling for the common factors across quantiles. to cope with the endogeneity issue due to simultaneous network spillovers, we adopt the instrumental variable quantile regression ( ivqr ) estimation and derive the consistency and asymptotic normality of the ivqr estimator using the near epoch dependence property of the network process. via monte carlo simulations, we confirm the satisfactory performance of the ivqr estimator across different quantiles under the different network structures. finally, we demonstrate the usefulness of our proposed approach with an application to the dataset on the stocks traded in nyse and nasdaq in 2016.
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arxiv:2111.07633
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accurate programming is a practical approach to producing high quality programs. it combines ideas from test - automation, test - driven development, agile programming, and other state of the art software development methods. in addition to building on approaches that have proven effective in practice, it emphasizes concepts that help programmers sharpen their understanding of both the problems they are solving and the solutions they come up with. this is achieved by encouraging programmers to think about programs in terms of properties.
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arxiv:1109.0786
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in this paper, we relatively extend the definition of global clustering coefficient to another clustering, which we call it relative clustering coefficient. the idea of this definition is to ignore the edges in the network that the probability of having an edge is 0. here, we also consider a model as an example that using relative clustering coefficient is better than global clustering coefficient for comparing networks and also checking the properties of the networks.
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arxiv:2106.05145
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we consider a left - right symmetric su ( 4 ) _ c \ times su ( 2 ) _ l \ times su ( 2 ) _ r ( 4 - 2 - 2 ) model with gravity mediated supersymmetry breaking. we find that with 4 - 2 - 2 compatible non - universal gaugino masses, t - b - \ tau yukawa coupling unification is consistent with neutralino dark matter abundance and with constraints from collider experiments ( except ( g - 2 ) _ { \ mu } ). the gluino mass lies close to that of the lightest neutralino, so that the gluino co - annihilation channel plays an important role in determining the neutralino relic abundance. by relaxing the yukawa unification constraint we find stau and stop masses as low as 200 - 220 gev. we highlight some benchmark points for these cases with 40 < \ tan \ beta < 58.
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arxiv:0903.5204
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this paper is devoted to the development and applications of some ( new ) basic concepts in lie theory, both from ` computational " and " observability " viewpoint. we specify set of all " g - equivariant " maps from a given lie group g to the underlying manifold m, namely $ g $ - set, and also we introduce " conjugacy " in lie group theory. the next goal of this paper is detailed analysis of the g - sets in connection with underlying transformation groups and providing a rigorous theoretical justification of " g - sets ", when a group of transformations g acts on manifold m.
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arxiv:1201.3741
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the long - lived radioactive element thorium can potentially provide a simple and direct clock to determine the age of our galaxy. spectroscopic investigations of thorium in metal - poor stars have yielded some promising initial results. we discuss the major observational and theoretical limitations in thorium cosmochronometry, and point out the ways in which the implied galactic ages from thorium abundances can be made more accurate.
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arxiv:astro-ph/0008185
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arabic is one of the oldest languages still in use today. as a result, several arabic - speaking regions have developed dialects that are unique to them. dialect and emotion recognition have various uses in arabic text analysis, such as determining an online customer ' s origin based on their comments. furthermore, intelligent chatbots that are aware of a user ' s emotions can respond appropriately to the user. current research in emotion detection in the arabic language lacks awareness of how emotions are exhibited in different dialects, which motivates the work found in this study. this research addresses the problems of dialect and emotion classification in arabic. specifically, this is achieved by building a novel framework that can identify and predict arabic dialects and emotions from a given text. the framework consists of three modules : a text - preprocessing module, a classification module, and a clustering module with the novel capability of building new dialect - aware emotion lexicons. the proposed framework generated a new emotional lexicon for different dialects. it achieved an accuracy of 88. 9 % in classifying arabic dialects, which outperforms the state - of - the - art results by 6. 45 percentage points. furthermore, the framework achieved 89. 1 - 79 % accuracy in detecting emotions in the egyptian and gulf dialects, respectively.
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arxiv:2502.09128
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we introduce dnabert - s, a tailored genome model that develops species - aware embeddings to naturally cluster and segregate dna sequences of different species in the embedding space. differentiating species from genomic sequences ( i. e., dna and rna ) is vital yet challenging, since many real - world species remain uncharacterized, lacking known genomes for reference. embedding - based methods are therefore used to differentiate species in an unsupervised manner. dnabert - s builds upon a pre - trained genome foundation model named dnabert - 2. to encourage effective embeddings to error - prone long - read dna sequences, we introduce manifold instance mixup ( mi - mix ), a contrastive objective that mixes the hidden representations of dna sequences at randomly selected layers and trains the model to recognize and differentiate these mixed proportions at the output layer. we further enhance it with the proposed curriculum contrastive learning ( c $ ^ 2 $ lr ) strategy. empirical results on 23 diverse datasets show dnabert - s ' s effectiveness, especially in realistic label - scarce scenarios. for example, it identifies twice more species from a mixture of unlabeled genomic sequences, doubles the adjusted rand index ( ari ) in species clustering, and outperforms the top baseline ' s performance in 10 - shot species classification with just a 2 - shot training. model, codes, and data are publicly available at \ url { https : / / github. com / magics - lab / dnabert _ s }.
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arxiv:2402.08777
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we address the origin of the cooper pairs in high - $ t _ c $ cuprates and the unique nature of the superconducting ( sc ) condensate. itinerant holes in an antiferromagnetic background form pairs spontaneously, without any ` glue ', defining a new quantum object the ` pairon '. in the incoherent pseudogap phase, above $ t _ c $ or within the vortex core, the pairon binding energies are distributed statistically, forming a ` cooper - pair glass '. contrary to conventional sc, it is the mutual pair - pair interaction that is responsable for the condensation. we give a natural explanation for the { \ it ergodic rigidity } of the excitation gap, being uniquely determined by the carrier concentration $ p $ and $ j $. the phase diagram can be understood, without spin fluctuations, in terms of a single energy scale $ \ sim j $, the exchange energy at the metal - insulator transition.
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arxiv:1704.03906
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software development for wireless sensor networks ( wsns ) is challenging due to characteristics of sensor nodes and the environment they are deployed in. testing software in a real wsn testbed allows users to get reliable test results. however, real testbeds become more expensive as the number of sensor nodes in the network grows. simulation tools are alternatives to real testbeds. they are cheaper, faster and repeatable. however, simulation results are not reliable as that of testbeds. therefore, there is a need for a testing tool that can leverage the advantages of testbeds and simulation tools. these tools are usually called hybrid simulators. in this survey, we discuss several hybrid simulators that use real sensor motes integrated with a simulator to make software development cheaper, repeatable and to make the results more reliable.
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arxiv:1602.01567
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it is challenging to parameterize the force field for calcium ions ( ca2 + ) in calcium - binding proteins because of their unique coordination chemistry that involves the surrounding atoms required for stability. in this work, we observed wide variation in ca2 + binding loop conformations of the ca2 + - binding protein calmodulin ( cam ), which adopts the most populated ternary structures determined from the md simulations, followed by ab initio quantum mechanical ( qm ) calculations on all twelve amino acids in the loop that coordinate ca2 + in aqueous solution. ca2 + charges were derived by fitting to the electrostatic potential ( esp ) in the context of a classical or polarizable force field ( pff ). we discovered that the atomic radius of ca2 + in conventional force fields is too large for the qm calculation to capture the variation in the coordination geometry of ca2 + in its ionic form, leading to unphysical charges. specifically, we found that the fitted atomic charges of ca2 + in the context of pff depend on the coordinating geometry of electronegative atoms from the amino acids in the loop. although nearby water molecules do not influence the atomic charge of ca2 +, they are crucial for compensating for the coordination of ca2 + due to the conformational flexibility in the ef - hand loop. our method advances the development of force fields for metal ions and protein binding sites in dynamic environments.
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arxiv:2011.07639
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this paper aims to generate physically - layered 3d humans from text prompts. existing methods either generate 3d clothed humans as a whole or support only tight and simple clothing generation, which limits their applications to virtual try - on and part - level editing. to achieve physically - layered 3d human generation with reusable and complex clothing, we propose a novel layer - wise dressed human representation based on a physically - decoupled diffusion model. specifically, to achieve layer - wise clothing generation, we propose a dual - representation decoupling framework for generating clothing decoupled from the human body, in conjunction with an innovative multi - layer fusion volume rendering method. to match the clothing with different body shapes, we propose an smpl - driven implicit field deformation network that enables the free transfer and reuse of clothing. extensive experiments demonstrate that our approach not only achieves state - of - the - art layered 3d human generation with complex clothing but also supports virtual try - on and layered human animation.
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arxiv:2408.11357
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we study the problem of the decentralized computation of entropy - regularized semi - discrete wasserstein barycenters over a network. building upon recent primal - dual approaches, we propose a sampling gradient quantization scheme that allows efficient communication and computation of approximate barycenters where the factor distributions are stored distributedly on arbitrary networks. the communication and algorithmic complexity of the proposed algorithm are shown, with explicit dependency on the size of the support, the number of distributions, and the desired accuracy. numerical results validate our algorithmic analysis.
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arxiv:2010.14325
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the ideal of the arc scheme of a double point or, equivalently, the differential ideal generated by the ideal of a double point is a primary ideal in an infinite - dimensional polynomial ring supported at the origin. this ideal has a rich combinatorial structure connecting it to singularity theory, partition identities, representation theory, and differential algebra. macaulay inverse system is a powerful tool for studying the structure of primary ideals which describes an ideal in terms of certain linear differential operators. in the present paper, we show that the inverse system of the ideal of the arc scheme of a double point is precisely a vector space spanned by all the wronskians of the variables and their formal derivatives. we then apply this characterization to extend our recent result on poincar \ ' e - type series for such ideals.
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arxiv:2405.08964
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recent surveys of the galactic plane in the dust continuum and co emission lines reveal that large ( $ \ gtrsim 50 $ ~ pc ) and massive ( $ \ gtrsim 10 ^ 5 $ ~ $ m _ \ odot $ ) filaments, know as giant molecular filaments ( gmfs ), may be linked to galactic dynamics and trace the mid - plane of the gravitational potential in the milky way. we have imaged one entire gmf located at $ l \ sim $ 52 - - 54 $ ^ \ circ $ longitude, gmf54 ( $ \ sim $ 68 ~ pc long ), in the empirical dense gas tracers using the hcn ( 1 - - 0 ), hnc ( 1 - - 0 ), hco $ ^ + $ ( 1 - - 0 ) lines, and their $ ^ { 13 } $ c isotopologue transitions, as well as the n $ _ 2 $ h $ ^ + $ ( 1 - - 0 ) line. we study the dense gas distribution, the column density probability density functions ( n - pdfs ) and the line ratios within the gmf. the dense gas molecular transitions follow the extended structure of the filament with area filling factors between 0. 06 and 0. 28 with respect to $ ^ { 13 } $ co ( 1 - - 0 ). we constructed the n - pdfs of h $ _ 2 $ for each of the dense gas tracers based on their column densities and assumed uniform abundance. the n - pdfs of the dense gas tracers appear curved in log - log representation, and the hco $ ^ + $ n - pdf has the largest log - normal width and flattest power - law slope index. studying the n - pdfs for sub - regions of gmf54, we found an evolutionary trend in the n - pdfs that high - mass star forming and photon - dominate regions ( pdrs ) have flatter power - law indices. the integrated intensity ratios of the molecular lines in gmf54 are comparable to those in nearby galaxies. in particular, the n $ _ 2 $ h $ ^ + $ / $ ^ { 13 } $ co ratio, which traces the dense gas fraction, has similar values in gmf54 and all nearby galaxies except ulirgs.
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arxiv:2003.05384
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for a matrix * - algebra b, consider the matrix * - algebra a consisting of the symmetric tensors in the n - fold tensor product of b. examples of such algebras in coding theory include the bose - mesner algebra and terwilliger algebra of the ( non ) binary hamming cube, and algebras arising in sdp - hierarchies for coding bounds using moment matrices. we give a computationally efficient block diagonalization of a in terms of a given block diagonalization of b, and work out some examples, including the terwilliger algebra of the binary - and nonbinary hamming cube. as a tool we use some basic facts about representations of the symmetric group.
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arxiv:0910.4515
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computation of the simplicial complexes of a large point cloud often relies on extracting a sample, to reduce the associated computational burden. the study considers sampling critical points of a morse function associated to a point cloud, to approximate the vietoris - rips complex or the witness complex and compute persistence homology. the effectiveness of the novel approach is compared with the farthest point sampling, in a context of classifying human face images into ethnics groups using persistence homology.
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arxiv:1805.06148
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to any adams - type spectrum $ e $, pstr \ k { a } gowski produced a symmetric monoidal stable $ \ infty $ - category $ syn _ e $ whose objects are, in a sense, ' ' formal adams spectral sequences ' '. $ syn _ e $ comes equipped with a lax symmetric monoidal functor $ \ nu _ e : sp \ to syn _ e $ from classical spectra, which embeds $ sp $ fully and faithfully in $ syn _ e $, and is a category with a natural notion of bigraded homotopy groups. the bigraded homotopy groups $ \ pi _ { *, * } \ nu _ ex $ systematically record information about the homotopy groups $ \ pi _ * x $ and the $ e $ - adams spectral sequence of $ x $. in this paper, we compute the $ \ nu _ { \ mathrm { h } \ mathbb { f } _ 2 } \ mathbb { f } _ 2 $ - adams spectral sequence of $ \ nu _ { \ mathrm { h } \ mathbb { f } _ 2 } tmf _ 2 ^ { \ wedge } $, synthetic versions of hidden $ 2 $ -, $ \ eta $ -, $ \ nu $ -, and $ \ overline { \ kappa } $ - extensions, and use this to deduce information about the homotopy ring structure of $ \ pi _ { *, * } \ nu _ { \ mathrm { h } \ mathbb { f } _ 2 } tmf _ 2 ^ { \ wedge } $.
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arxiv:2202.11305
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quantum dots defined in carbon nanotubes are a platform for both basic scientific studies and research into new device applications. in particular, they have unique properties that make them attractive for studying the coherent properties of single electron spins. to perform such experiments it is necessary to confine a single electron in a quantum dot with highly tunable barriers, but disorder has until now prevented tunable nanotube - based quantum - dot devices from reaching the single - electron regime. here, we use local gate voltages applied to an ultra - clean suspended nanotube to confine a single electron in both a single quantum dot and, for the first time, in a tunable double quantum dot. this tunability is limited by a novel type of tunnelling that is analogous to that in the klein paradox of relativistic quantum mechanics.
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arxiv:0907.2321
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we show that the electron and hole lande g factors in self - assembled iii - v quantum dots have a rich structure intermediate between that expected for paramagnetic atomic impurities and for bulk semiconductors. strain, dot geometry, and confinement energy significantly modify the effective g factors of the semiconductor material from which the dot and barrier are constructed, yet these effects are insufficient to explain our results. we find that the quantization of the quantum dot electronic states further quenches the orbital angular momentum of the dot states, pushing the electron g factor towards 2, even when all the semiconductor constituents of the dot have negative g factors. this leads to trends in the dot ' s electron g factors that are the opposite of those expected from the effective g factors of the dot and barrier material. both electron and hole g factors are strongly dependent on the magnetic field orientation ; hole g factors for inas / gaas quatum dots have large positive values along the growth direction and small negative values in - plane. the approximate shape of a quantum dot can be determined from measurements of this g factor asymmetry.
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arxiv:cond-mat/0410678
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with its electrically tunable light absorption and ultrafast photoresponse, graphene is a promising candidate for high - speed chip - integrated photonics. the generation mechanisms of photosignals in graphene photodetectors have been studied extensively in the past years. however, the knowledge about efficient light conversion at graphene pn - junctions has not yet been translated into high - performance devices. here, we present a graphene photodetector integrated on a silicon slot - waveguide, acting as a dual - gate to create a pn - junction in the optical absorption region of the device. while at zero bias the photo - thermoelectric effect is the dominant conversion process, an additional photoconductive contribution is identified in a biased configuration. extrinsic responsivities of 35 ma / w, or 3. 5 v / w, at zero bias and 76 ma / w at 300 mv bias voltage are achieved. the device exhibits a 3 db - bandwidth of 65 ghz, which is the highest value reported for a graphene - based photodetector.
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arxiv:1610.05526
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superconductors exhibit remarkable properties such as zero resistivity and diamagnetism at the boiling temperature of liquid hydrogen ( 20 k ) and even aboven the boiling temperature of liquid nitrogen ( 77 k ), making them promising candidates for various applications including electrical engines, energy generation, storage, and high - tech devices like single photon detectors. in this overview, we explore the correlation between ceramic superconductors and the united nations ( un ) development goals, emphasizing their potential impact on sustainable development. through bibliometric analysis, we underscore the significance of ceramic superconductors in addressing global challenges outlined by the un. additionally, we discuss the application of supermagnets and second - generation tapes in healthcare systems, particularly in magnetic resonance imaging ( mri ) devices for diagnostic imaging. electric superconducting motors offer a clean alternative to highly polluting diesel engines in maritime transportation and superconducting wires / cables enable effective transport of energy on large scale as well as in industrial structures. magnetic levitation technology holds promise for developing zero - emission public transportation systems, and magnetic separation with strong magnets will contribute to solve the microplastic pollution. the combination of superconductivity with the planned hydrogen economy further offers new possibilities to bring superconductivity to common applications. at the nanoscale, superconducting nanowire single photon detectors ( snspds ) enable real - time monitoring of environmental health, exemplified by applications in plant physiology, and superconducting qubits provide the best - engineered structures for quantum computers. however it is still crordwork to works with superconductors un develepoment goals.
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arxiv:2409.17307
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for the gaussian free field on a $ ( d + 1 ) $ - regular tree with $ d \ geq 2 $, we study the percolative properties of its level sets in the critical and the near - critical regime. in particular, we show the continuity of the percolation probability, derive an exact symptotic tail estimate for the cardinality of the connected component of the critical level set, and describe the asymptotic behaviour of the percolation probability in the near - critical regime.
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arxiv:2302.02753
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we prove that in an open and dense set, symplectic linear cocycles over time one maps of anosov flows, have positive lyapunov exponents for srb measures.
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arxiv:1705.00482
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scalar - tensor theories have shown great potential in inducing tailored modifications compared to cosmic evolution in the $ \ lambda $ cdm model. we reconsider quintessence models in this work in the context of three driving potentials. we center the action of these models in the late universe which leaves early $ \ lambda $ cdm cosmology unchanged. the effects show the potential of producing a faster expanding cosmology with a high hubble constant. the models are constrained using the cosmic chronometer data, pantheon plus, and transversal baryonic acoustic oscillation data.
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arxiv:2504.07876
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the independent component analysis ( ica ) algorithm is implemented as a neural network for separating signals of different origin in astrophysical sky maps. due to its self - organizing capability, it works without prior assumptions on the signals, neither on their frequency scaling, nor on the signal maps themselves ; instead, it learns directly from the input data how to separate the physical components, making use of their statistical independence. to test the capabilities of this approach, we apply the ica algorithm on sky patches, taken from simulations and observations, at the microwave frequencies, that are going to be deeply explored in a few years on the whole sky, by the microwave anisotropy probe ( map ) and by the { \ sc planck } surveyor satellite. the maps are at the frequencies of the low frequency instrument ( lfi ) aboard the { \ sc planck } satellite ( 30, 44, 70 and 100 ghz ), and contain simulated astrophysical radio sources, cosmic microwave background ( cmb ) radiation, and galactic diffuse emissions from thermal dust and synchrotron. we show that the ica algorithm is able to recover each signal, with precision going from 10 % for the galactic components to percent for cmb ; radio sources are almost completely recovered down to a flux limit corresponding to $ 0. 7 \ sigma _ { cmb } $, where $ \ sigma _ { cmb } $ is the rms level of cmb fluctuations. the signal recovering possesses equal quality on all the scales larger then the pixel size. in addition, we show that the frequency scalings of the input signals can be partially inferred from the ica outputs, at the percent precision for the dominant components, radio sources and cmb.
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arxiv:astro-ph/0002257
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forecasting a typical object ' s future motion is a critical task for interpreting and interacting with dynamic environments in computer vision. event - based sensors, which could capture changes in the scene with exceptional temporal granularity, may potentially offer a unique opportunity to predict future motion with a level of detail and precision previously unachievable. inspired by that, we propose to integrate the strong learning capacity of the video diffusion model with the rich motion information of an event camera as a motion simulation framework. specifically, we initially employ pre - trained stable video diffusion models to adapt the event sequence dataset. this process facilitates the transfer of extensive knowledge from rgb videos to an event - centric domain. moreover, we introduce an alignment mechanism that utilizes reinforcement learning techniques to enhance the reverse generation trajectory of the diffusion model, ensuring improved performance and accuracy. through extensive testing and validation, we demonstrate the effectiveness of our method in various complex scenarios, showcasing its potential to revolutionize motion flow prediction in computer vision applications such as autonomous vehicle guidance, robotic navigation, and interactive media. our findings suggest a promising direction for future research in enhancing the interpretative power and predictive accuracy of computer vision systems.
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arxiv:2410.08649
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evolution of structure of spherical sio2 nanoparticles upon cooling from the melt has been investigated via molecular - dynamics ( md ) simulations under non - periodic boundary conditions ( npbc ). we use the pair interatomic potentials which have weak coulomb interaction and morse type short - range interaction. the change in structure of sio2 nanoparticles upon cooling process has been studied through the partial radial distribution functions ( prdfs ), coordination number and bond - angle distributions at different temperatures. the core and surface structures of nanoparticles have been studied in details. our results show significant temperature dependence of structure of nanoparticles. moreover, temperature dependence of concentration of structural defects in nanoparticles upon cooling from the melt toward glassy state has been found and discussed.
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arxiv:0901.2029
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although deeper and larger neural networks have achieved better performance, the complex network structure and increasing computational cost cannot meet the demands of many resource - constrained applications. existing methods usually choose to execute or skip an entire specific layer, which can only alter the depth of the network. in this paper, we propose a novel method called dynamic multi - path neural network ( dmnn ), which provides more path selection choices in terms of network width and depth during inference. the inference path of the network is determined by a controller, which takes into account both previous state and object category information. the proposed method can be easily incorporated into most modern network architectures. experimental results on imagenet and cifar - 100 demonstrate the superiority of our method on both efficiency and overall classification accuracy. to be specific, dmnn - 101 significantly outperforms resnet - 101 with an encouraging 45. 1 % flops reduction, and dmnn - 50 performs comparably to resnet - 101 while saving 42. 1 % parameters.
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arxiv:1902.10949
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we say that two permutations $ \ pi $ and $ \ rho $ have separated descents at position $ k $ if $ \ pi $ has no descents before position $ k $ and $ \ rho $ has no descents after position $ k $. we give a counting formula, in terms of reduced word tableaux, for computing the structure constants of products of schubert polynomials indexed by permutations with separated descents, and recognize that these structure constants are certain edelman - greene coefficients. our approach uses generalizations of sch \ " utzenberger ' s jeu de taquin algorithm and the edelman - greene correspondence via bumpless pipe dreams.
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arxiv:2105.01591
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the first part of these lectures contains an introductory review of the ads / cft duality and of its tests. applications to thermal gauge theory are also discussed briefly. the second part is devoted to a review of gauge - string dualities based on various warped conifold backgrounds, and to their cosmological applications.
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arxiv:0803.1315
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we study homotopy epimorphisms and covers formulated in terms of derived tate ' s acyclicity for commutative c * - algebras and their non - archimedean counterparts. we prove that a homotopy epimorphism between commutative c * - algebras precisely corresponds to a closed immersion between the compact hausdorff topological spaces associated to them, and a cover of a commutative c * - algebra precisely corresponds to a topological cover of the compact hausdorff topological space associated to it by closed immersions admitting a finite subcover. this permits us to prove derived and non - derived descent for banach modules over commutative c * - algebras.
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arxiv:2103.11722
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we show that scalar quantum field theory in four euclidean dimensions with global $ o ( n ) ^ 3 $ symmetry and imaginary tetrahedral coupling is asymptotically free and bounded from below in the large - n limit. while the hamiltonian is non - hermitian, the full quantum effective action for the large - n theory only depends on the square of that coupling which is real. a perturbative analysis uncovers that the renormalization group flow of the quartic couplings connects a gaussian ultraviolet fixed point to a strongly interacting theory in the infrared. this realizes a renormalizable field theory which exhibits non - trivial dynamics, such as direct scattering, while still being analytically tractable also non - perturbatively. our findings open up a way to address outstanding problems in strongly coupled theories from first principles.
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arxiv:2301.09514
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we give an independent, and perhaps somewhat simplified, description of the product in negative tate - cohomology ( the generalised version for compact lie - groups ). we describe, but do not compute, the corresponding action of the dyer - - lashof - algebra, using the linear - isometries operad.
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arxiv:1007.3355
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[ background : ] the band structure of the negative - parity states of $ ^ { 24 } $ mg has not yet been clarified. the $ k ^ \ pi = 0 ^ - $, $ k ^ \ pi = 1 ^ - $, and $ k ^ \ pi = 3 ^ - $ bands have been suggested, but the assignments have been inconsistent between experiments and theories. [ purpose : ] negative - parity states of $ ^ { 24 } $ mg are investigated by microscopic structure and reaction calculations via proton and alpha inelastic scattering to clarify the band assignment for the observed negative - parity spectra. [ method : ] the structure of $ ^ { 24 } $ mg was calculated using the antisymmetrized molecular dynamics ~ ( amd ). proton and alpha inelastic reactions were calculated using microscopic coupled - channel ( mcc ) calculations by folding the melbourne $ g $ - matrix $ nn $ interaction with the amd densities of $ ^ { 24 } $ mg. [ results : ] the member states of the $ k ^ \ pi = 0 ^ + $, $ k ^ \ pi = 2 ^ + $, $ k ^ \ pi = 0 ^ - $, $ k ^ \ pi = 1 ^ - $, and $ k ^ \ pi = 3 ^ - $ bands of $ ^ { 24 } $ mg were obtained through the amd result. in the mcc + amd results for proton and alpha elastic and inelastic cross sections, reasonable agreements were obtained with existing data, except in the case of the $ 4 ^ + _ 1 $ state. [ conclusions : ] the $ 3 ^ - $ state of the $ k ^ \ pi = 3 ^ - $ band and the $ 1 ^ - $ and $ 3 ^ - $ states of the $ k ^ \ pi = 0 ^ - $ bands were assigned to the $ 3 ^ - _ 1 $ ( 7. 62 mev ), $ 1 ^ - _ 1 $ ( 7. 56 mev ), and $ 3 ^ - _ 2 $ ( 8. 36 mev ) states, respectively. the present amd calculation is the first microscopic structure calculation to reproduce the energy ordering of the $ k ^ \ pi = 0 ^ - $, $ k ^ \ pi = 1 ^ - $, and $ k ^ \ pi = 3 ^ - $ bands of $ ^ { 24 } $ mg.
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arxiv:2010.07578
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we study the two - dimensional navier - stokes equations forced by random noise with a diffusive term generalized via a fractional laplacian that has a positive exponent strictly less than one. because intermittent jets are inherently three - dimensional, we instead adapt the theory of intermittent form of the two - dimensional stationary flows to the stochastic approach presented by hofmanov $ \ acute { \ mathrm { a } } $, zhu $ \ & $ zhu ( 2019, arxiv : 1912. 11841 [ math. pr ] ) and prove its non - uniqueness in law.
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arxiv:2008.04760
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junctions of multiple one - dimensional quantum wires of interacting electrons have received considerable theoretical attention as a basic constituent of quantum circuits. while results have been obtained on these models using bosonization and density matrix renormalization group ( dmrg ) methods, another powerful technique is based on direct perturbation theory in the bulk interactions, combined with the renormalization group ( rg ) and summed in the random phase approximation ( rpa ). this technique has so far only been applied to the case where finite length interacting wires are attached to non - interacting fermi liquid leads. we reformulate it in terms of the single - particle s - matrix, formally unifying treatments of junctions of different numbers of leads, and extend this method to cover the case of infinite length interacting leads obtaining results on 2 - lead and 3 - lead junctions in good agreement with previous bosonization and dmrg results.
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arxiv:1601.00510
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in late fusion, each modality is processed in a separate unimodal convolutional neural network ( cnn ) stream and the scores of each modality are fused at the end. due to its simplicity late fusion is still the predominant approach in many state - of - the - art multimodal applications. in this paper, we present a simple neural network module for leveraging the knowledge from multiple modalities in convolutional neural networks. the propose unit, named multimodal transfer module ( mmtm ), can be added at different levels of the feature hierarchy, enabling slow modality fusion. using squeeze and excitation operations, mmtm utilizes the knowledge of multiple modalities to recalibrate the channel - wise features in each cnn stream. despite other intermediate fusion methods, the proposed module could be used for feature modality fusion in convolution layers with different spatial dimensions. another advantage of the proposed method is that it could be added among unimodal branches with minimum changes in the their network architectures, allowing each branch to be initialized with existing pretrained weights. experimental results show that our framework improves the recognition accuracy of well - known multimodal networks. we demonstrate state - of - the - art or competitive performance on four datasets that span the task domains of dynamic hand gesture recognition, speech enhancement, and action recognition with rgb and body joints.
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arxiv:1911.08670
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a state of a quantum systems can be regarded as { \ it classical } ( { \ it quantum } ) with respect to measurements of a set of canonical observables iff there exists ( does not exist ) a well defined, positive phase space distribution, the so called galuber - sudarshan $ p $ - representation. we derive a family of classicality criteria that require that averages of positive functions calculated using $ p $ - representation must be positive. for polynomial functions, these criteria are related to 17 - th hilbert ' s problem, and have physical meaning of generalized squeezing conditions ; alternatively, they may be interpreted as { \ it non - classicality witnesses }. we show that every generic non - classical state can be detected by a polynomial that is a sum of squares of other polynomials ( sos ). we introduce a very natural hierarchy of states regarding their degree of quantumness, which we relate to the minimal degree of a sos polynomial that detects them is introduced. polynomial non - classicality witnesses can be directly measured.
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arxiv:quant-ph/0408029
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a full three - dimensional model for the calculation of the electronic structure of semiconductor quantum dots ( qd ) and molecules ( qdm ) grown on high index surfaces and / or in the presence of an external magnetic field is presented. the strain distribution of the dots is calculated using continuum elasticity and singe - particle states are extracted from the nonsymmetrized eight - band k. p theory. the model properly takes into account the effects of different substrate orientation by rotation of the coordinate system in the way that one coordinate coincides with the growth direction, whereas the effects of a tilted external magnetic field are taken into account throught the zeeman effect and employing a gauge invariant scheme based on wilson ' s formulation of lattice gauge theory. we point out the role of piezoelectricity for inas / gaas qds grown on [ 11k ], where k = 1, 2, 3, 4, 5, 7, 9 and for qdms containing eight inas / gaas qds grown on [ 11l ], where l = 1, 2, 3. we predict the variation of the transition energies of the qdm as a function of substrate orientation and interdot distances in the molecule. we address the magnetic field direction dependent variation of the electronic properties of qd and qdm.
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arxiv:cond-mat/0703726
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perform complicated chemical reactions with little maintenance to realize planet - scale terraforming. = = climate engineering = = climate engineering is a form of planetary engineering which involves the process of deliberate and large - scale alteration of the earth ' s climate system to combat climate change. examples of geoengineering are carbon dioxide removal ( cdr ), which removes carbon dioxide from the atmosphere, and solar radiation modification ( srm ) to reflect solar energy to space. carbon dioxide removal ( cdr ) has multiple practices, the simplest being reforestation, to more complex processes such as direct air capture. the latter is rather difficult to deploy on an industrial scale, for high costs and substantial energy usage would be some aspects to address. examples of srm include stratospheric aerosol injection ( sai ) and marine cloud brightening ( mcb ). when a volcano erupts, small particles known as aerosols proliferate throughout the atmosphere, reflecting the sun ' s energy back into space. this results in a cooling effect, and humanity could conceivably inject these aerosols into the stratosphere, spurring large - scale cooling. one proposal for mcb involves spraying a vapor into low - laying sea clouds, creating more cloud condensation nuclei. this would in theory result in the cloud becoming whiter, and reflecting light more efficiently. = = see also = = astroengineering macro - engineering megascale engineering moving the earth virgin earth challenge = = references = = = = further reading = = angelo, joseph a. jr. ( 2006 ). " planetary engineering ". encyclopedia of space and astronomy. new york : facts on file. pp. 462 – 462. isbn 978 - 1 - 4381 - 1018 - 9. sagan, carl ( december 1973 ). " planetary engineering on mars ". icarus. 20 ( 4 ) : 513 – 514. bibcode : 1973icar... 20.. 513s. doi : 10. 1016 / 0019 - 1035 ( 73 ) 90026 - 2. = = external links = = geoengineering : a worldchanging retrospective – overview of articles on geoengineering from the sustainability site worldchanging
|
https://en.wikipedia.org/wiki/Planetary_engineering
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in this paper we study a distance - dependent surface tension, defined as the free - energy cost to put metastable states at a given distance. this will be done in the framework of a disordered microscopic model with kac interactions that can be solved in the mean - field limit.
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arxiv:0912.2764
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this paper deals with the modular irregularity strength of a graph of n vertices, a new graph invariant, modified from the irregularity strength, by changing the condition of the vertex - weight set associate to the well - known irregular labeling from n distinct positive integer to z _ n - the group of integer modulo n. investigating the triangular book graph b _ m ^ ( ( 3 ) ), we first find the irregularity strength of triangular book graph s ( b _ m ^ ( ( 3 ) ) ), as the lower bound for the modular irregularity strength, and then construct a modular irregular s ( b _ m ^ ( ( 3 ) ) ) - labeling. the result shows that triangular book graphs admit a modular irregular labeling and its modular irregularity strength and irregularity strength are equal, except for a small case and the infinity property.
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arxiv:2111.12897
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electronic medical records ( emrs ) are stored in relational databases. it can be challenging to access the required information if the user is unfamiliar with the database schema or general database fundamentals. hence, researchers have explored text - to - sql generation methods that provide healthcare professionals direct access to emr data without needing a database expert. however, currently available datasets have been essentially " solved " with state - of - the - art models achieving accuracy greater than or near 90 %. in this paper, we show that there is still a long way to go before solving text - to - sql generation in the medical domain. to show this, we create new splits of the existing medical text - to - sql dataset mimicsql that better measure the generalizability of the resulting models. we evaluate state - of - the - art language models on our new split showing substantial drops in performance with accuracy dropping from up to 92 % to 28 %, thus showing substantial room for improvement. moreover, we introduce a novel data augmentation approach to improve the generalizability of the language models. overall, this paper is the first step towards developing more robust text - to - sql models in the medical domain. \ footnote { the dataset and code will be released upon acceptance.
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arxiv:2303.12898
|
multicasting is a vital information dissemination technique in software - defined networking ( sdn ). with sdn, a multicast service can incorporate network functions implemented at different nodes, which is referred to as software - defined multicast. emerging ubiquitous wireless networks for 5g and beyond ( b5g ) inherently support multicast. however, the broadcast nature of wireless channels, especially in dense deployments, leads to neighborhood interference as a primary system degradation factor, which introduces a new challenge for software - defined multicast in wireless mesh networks. to tackle this, this paper introduces an innovative approach, based on the idea of minimizing both the total length cost of the multicast tree and the interference at the same time. accordingly, a novel bicriteria optimization problem is formulated - - \ emph { minimum interference steiner tree ( mist ) }, which is the edge - weighted variant of the vertex - weighted secluded steiner tree problem \ cite { chechik2013secluded }. to solve the bicriteria problem, instead of resorting to heuristics, this paper employs an innovative approach that is an approximate algorithm for mist but with guaranteed performance. specifically, the approach exploits the monotone submodularity property of the interference metric and identifies pareto optimal solutions for mist, then converts the problem into the submodular minimization under steiner tree constraints, and designs a two - stage relaxation algorithm. simulation results demonstrate and validate the performance of the proposed algorithm.
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arxiv:2312.04418
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we study possible saturation effects in the total cross - section describing interaction of ultrahigh energy neutrinos with nucleons. this analysis is performed within the two approaches, i. e. within the golec - biernat w \ " usthoff saturation model and within the scheme unifying the dglap and bfkl dynamics incorporating non - linear screening effects which follow from the balitzki - kovchegov equation. the structure functions in both approaches are constrained by hera data. it is found that screening effects affect extrapolation of the neutrino - nucleon total cross - sections to ultrahigh neutrino energies $ e _ { \ nu } $ and reduce their magnitude by a factor equal to about 2 at $ e _ { \ nu } \ sim 10 ^ { 12 } gev $. this reduction becomes amplified by nuclear shadowing in the case of the neutrino - nucleus cross - sections and approximate estimate of this effect is performed.
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arxiv:hep-ph/0303209
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based on a rare - earth gd atom with 4 $ f $ electrons, through first - principles calculations, we demonstrate that the janus 2h - gdibr monolayer exhibits an intrinsic ferromagnetic ( fm ) semiconductor character with an indirect band gap of 0. 75 ev, high curie temperature t $ _ { c } $ of 260 k, significant magnetic moment of 8 $ \ mu _ { b } $ / f. u. ( f. u. = formula unit ), in - plane magnetic anisotropy ( ima ) and large spontaneous valley polarization of 118 mev. the mae, inter - atomic distance or angle, and t $ _ { c } $ can be efficiently modulated by in - plane strains and charge carrier doping. under the strain range from $ - $ 5 % to 5 % and charge carrier doping from $ - $ 0. 3e to 0. 3e / f. u., the system still remains fm ordering and the corresponding t $ _ { c } $ can be modulated by strains from 233 k to 281 k and by charge carrier doping from 140 k to 245 k. interestingly, under various strains, the matrix elements differences ( $ d _ { z ^ { 2 } } $, $ d _ { yz } $ ), ( $ d _ { x ^ { 2 } - y ^ { 2 } } $, $ d _ { xy } $ ) and ( $ p _ { x } $, $ p _ { y } $ ) of gd atoms dominate the mae behaviors, which originates from the competition between the contributions of gd - $ d $, gd - $ p $ orbitals, and $ p $ orbitals of halogen atoms based on the second - order perturbation theory. inequivalent dirac valleys are not energetic degenerate due to the time - reversal symmetry breaking in the janus 2h - gdibr monolayer. a considerable valley gap between the berry curvature at the k and k $ ^ { \ prime } $ points provides an opportunity to selectively control the valley freedom and to manipulate the anomalous hall effect. external tensile ( compressive ) strain further increases ( decreases ) the valley gap up to a maximum ( minimum ) value of 158 ( 37 ) mev, indicating that the valley polarization in the janus 2h - gdibr monolayer is robust to the external strains.
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arxiv:2208.13613
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ring f [ x ]. the field f ( ( x ) ) of laurent series i = k ∞ a i x i ( k ∈ z, a i ∈ f ) { \ displaystyle \ sum _ { i = k } ^ { \ infty } a _ { i } x ^ { i } \ ( k \ in \ mathbb { z }, a _ { i } \ in f ) } over a field f is the field of fractions of the ring f [ [ x ] ] of formal power series ( in which k ≥ 0 ). since any laurent series is a fraction of a power series divided by a power of x ( as opposed to an arbitrary power series ), the representation of fractions is less important in this situation, though. = = = = residue fields = = = = in addition to the field of fractions, which embeds r injectively into a field, a field can be obtained from a commutative ring r by means of a surjective map onto a field f. any field obtained in this way is a quotient r / m, where m is a maximal ideal of r. if r has only one maximal ideal m, this field is called the residue field of r. the ideal generated by a single polynomial f in the polynomial ring r = e [ x ] ( over a field e ) is maximal if and only if f is irreducible in e, i. e., if f cannot be expressed as the product of two polynomials in e [ x ] of smaller degree. this yields a field f = e [ x ] / ( f ( x ) ). this field f contains an element x ( namely the residue class of x ) which satisfies the equation f ( x ) = 0. for example, c is obtained from r by adjoining the imaginary unit symbol i, which satisfies f ( i ) = 0, where f ( x ) = x2 + 1. moreover, f is irreducible over r, which implies that the map that sends a polynomial f ( x ) r [ x ] to f ( i ) yields an isomorphism r [ x ] / ( x 2 + 1 ) c. { \ displaystyle \ mathbf { r } [ x ] / \ left ( x ^ { 2 } + 1 \ right ) \ { \ stackrel { \ cong } { \ longrightarrow } } \ \ mathbf { c }. } = =
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https://en.wikipedia.org/wiki/Field_(mathematics)
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in this paper, we investigate channel estimation for a large intelligent surface ( lis ) aided multiple - input multiple - output ( mimo ) communication system. due to the close proximity of communication devices and lis terminal, the desired channels can be modeled as line - of - sight channels which are ill - conditioned. to estimate these channel matrices with high quality, we propose a two - stage channel estimation method. in particular, we employ the conventional time - division duplexing based mimo channel estimation technique in the first stage to estimate the direct mimo channel between the end terminals. in the second stage, we propose to use a recently developed bilinear adaptive vector approximate message passing ( badvamp ) algorithm to estimate ill - conditioned lis channels. the badvamp method has been shown to be accurate and robust for ill - conditioned dictionary learning problems in compressed sensing. we also propose a phase shift design for the lis using the estimated channels. specifically, we formulate an optimization problem that maximizes the total channel gain at the user. a closed - form expression to obtain the phase shift of each passive element in the lis is also derived. numerical results show that the proposed badvamp based lis channel estimation performs better than its counterpart scheme bilinear generalized amp ( bigamp ), especially when channel matrices are ill - conditioned.
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arxiv:1912.10671
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spin pumping and spin - transfer torques are two reciprocal phenomena widely studied in ferromagnetic materials. however, pumping from antiferromagnets and its relation to current - induced torques have not been explored. by calculating how electrons scatter off a normal metal - antiferromagnetic interface, we derive pumped spin and staggered spin currents in terms of the staggered field, the magnetization, and their rates of change. for both compensated and uncompensated interfaces, spin pumping is of a similar magnitude as in ferromagnets with a direction controlled by the polarization of the driving microwave. the pumped currents are connected to current - induced torques via onsager reciprocity relations.
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arxiv:1404.4023
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in the rapidly evolving landscape of large language models ( llms ), introduction of well - defined and standardized evaluation methodologies remains a crucial challenge. this paper traces the historical trajectory of llm evaluations, from the foundational questions posed by alan turing to the modern era of ai research. we categorize the evolution of llms into distinct periods, each characterized by its unique benchmarks and evaluation criteria. as llms increasingly mimic human - like behaviors, traditional evaluation proxies, such as the turing test, have become less reliable. we emphasize the pressing need for a unified evaluation system, given the broader societal implications of these models. through an analysis of common evaluation methodologies, we advocate for a qualitative shift in assessment approaches, underscoring the importance of standardization and objective criteria. this work serves as a call for the ai community to collaboratively address the challenges of llm evaluation, ensuring their reliability, fairness, and societal benefit.
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arxiv:2311.02049
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incremental class learning, a scenario in continual learning context where classes and their training data are sequentially and disjointedly observed, challenges a problem widely known as catastrophic forgetting. in this work, we propose a novel incremental class learning method that can significantly reduce memory overhead compared to previous approaches. apart from conventional classification scheme using softmax, our model bases on an autoencoder to extract prototypes for given inputs so that no change in its output unit is required. it stores only the mean of prototypes per class to perform metric - based classification, unlike rehearsal approaches which rely on large memory or generative model. to mitigate catastrophic forgetting, regularization methods are applied on our model when a new task is encountered. we evaluate our method by experimenting on cifar - 100 and cub - 200 - 2011 and show that its performance is comparable to the state - of - the - art method with much lower additional memory cost.
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arxiv:1907.07872
|
promoted the social view of mathematics, calling it a " humanistic " approach, similar to but not quite the same as that associated with alvin white ; one of hersh ' s co - authors, philip j. davis, has expressed sympathy for the social view as well. = = = beyond the traditional schools = = = = = = = unreasonable effectiveness = = = = rather than focus on narrow debates about the true nature of mathematical truth, or even on practices unique to mathematicians such as the proof, a growing movement from the 1960s to the 1990s began to question the idea of seeking foundations or finding any one right answer to why mathematics works. the starting point for this was eugene wigner ' s famous 1960 paper " the unreasonable effectiveness of mathematics in the natural sciences ", in which he argued that the happy coincidence of mathematics and physics being so well matched seemed to be unreasonable and hard to explain. = = = = popper ' s two senses of number statements = = = = realist and constructivist theories are normally taken to be contraries. however, karl popper argued that a number statement such as " 2 apples + 2 apples = 4 apples " can be taken in two senses. in one sense it is irrefutable and logically true. in the second sense it is factually true and falsifiable. another way of putting this is to say that a single number statement can express two propositions : one of which can be explained on constructivist lines ; the other on realist lines. = = = = philosophy of language = = = = innovations in the philosophy of language during the 20th century renewed interest in whether mathematics is, as is often said, the language of science. although some mathematicians and philosophers would accept the statement " mathematics is a language " ( most consider that the language of mathematics is a part of mathematics to which mathematics cannot be reduced ), linguists believe that the implications of such a statement must be considered. for example, the tools of linguistics are not generally applied to the symbol systems of mathematics, that is, mathematics is studied in a markedly different way from other languages. if mathematics is a language, it is a different type of language from natural languages. indeed, because of the need for clarity and specificity, the language of mathematics is far more constrained than natural languages studied by linguists. however, the methods developed by frege and tarski for the study of mathematical language have been extended greatly by tarski ' s student richard montague and other linguists working in formal semantics to show
|
https://en.wikipedia.org/wiki/Philosophy_of_mathematics
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we consider a reaction - diffusion equation in narrow random channels. we approximate the generalized solution to this equation by the corresponding one on a random graph. by making use of large deviation analysis we study the asymptotic wave front propagation.
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arxiv:1303.6943
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