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the reaction 243 am ( n, 2n ) populates the t of 16 hours ground state 242 g am with j of 1 or the 242 m am isomer state j of 5 with t of 141 years. the former state 242 g am mostly beta decays to 242 cm, or transmutes to 242 pu via electron capture. the absolute yield of 242 g am is compatible with the measured data, estimated by the alpha activity of 242 cm by norris in 1983. the branching ratio defined by the ratio of the populations of the lowest intrinsic states of 242 am. calculated yields of ground 242 g am and isomer 242 m am states of the residual nucleus 242 am are used to predict the relative yield of isomer. these populations defined by the gamma decay of the excited states, described by the standard kinetic equation. the ordering of the low and high spin states is different in case of 236 np and 242 am nuclei, that explains different shapes of relative yields near the ( n, 2n ) reaction threshold, though the excitation energy dependences are similar. data of 243 am ( n, f ) at 5 mev and 15 mev by drapchinsky in 2004, support calculated 243am ( n, xnf ) prefission neutron contribution to prompt fission neutron spectra and calculated exclusive neutron spectra of 243 am ( n, 2n ) feeding the 242 g am and isomer 242 m am states.
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arxiv:2406.15445
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we propose a method for detecting single chiral phonons that will enable their use as dark - matter detectors. we suggest metal - - organic frameworks ( mofs ) as detector materials, as their flexibility yields low - energy chiral phonons with measurable magnetic moments, and their anisotropy leads to directional sensitivity, which mitigates background contamination. to demonstrate our proposal, we calculate the phononic structure of the mof inf $ _ 3 $ ( $ 4, 4 ' $ - bipyridine ), and show that it has highly chiral acoustic phonons. detection of such chiral phonons via their magnetic moments would dramatically lower the excitation energy threshold for dark matter detection to the energy of a single phonon. we show that single phonon detection in a mof would extend detector reach ten or more orders of magnitude below current limits, enabling exploration of a multitude of as - yet - unprobed dark matter candidates.
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arxiv:2301.07617
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we report detailed studies on non - equilibrium magnetic behavior of antiferromagnetic co _ 3o _ 4 nanoparticles. temperature and field dependence of magnetization, wait time dependence of magnetic relaxation ( aging ), memory effects and temperature dependence of specific heat have been investigated to understand the magnetic behavior of these particles. we find that the system shows some features characteristic of nanoparticle magnetism such as bifurcation of field cooled ( fc ) and zero field cooled ( zfc ) susceptibilities and a slow relaxation of magnetization. however, strangely, the temperature at which the zfc magnetization peaks coincides with the bifurcation temperature and does not shift on application of magnetic fields up to 1 koe, unlike most other nanoparticle systems. aging effects in these particles are negligible in both fc and zfc protocol and memory effects are present only in fc protocol. we estimate the n \ ' eel temperature by using fisher ' s relation as well as directly by measurement of specific heat, thus testing the validity of fisher ' s relation for nanoparticles. we show that co3o4 nanoparticles constitute a unique aniferromagnetic system which develops a magnetic moment in the paramagnetic state because of antiferromagnetic correlations and enters into a blocked state above the n \ ' eel temperature.
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arxiv:1102.2303
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we study multi - budgeted variants of the classic minimum cut problem and graph separation problems that turned out to be important in parameterized complexity : skew multicut and directed feedback arc set. in our generalization, we assign colors $ 1, 2,..., \ ell $ to some edges and give separate budgets $ k _ { 1 }, k _ { 2 },..., k _ { \ ell } $. let $ e _ { i } $ be the set of edges of color $ i $. the solution $ c $ for the multi - budgeted variant of a graph separation problem not only needs to satisfy the usual separation requirements, but also needs to satisfy that $ | c \ cap e _ { i } | \ leq k _ { i } $ for every $ i \ in \ { 1,..., \ ell \ } $. contrary to the classic minimum cut problem, the multi - budgeted variant turns out to be np - hard even for $ \ ell = 2 $. we propose fpt algorithms parameterized by $ k = k _ { 1 } +... + k _ { \ ell } $ for all three problems. to this end, we develop a branching procedure for the multi - budgeted minimum cut problem that measures the progress of the algorithm not by reducing $ k $ as usual, by but elevating the capacity of some edges and thus increasing the size of maximum source - to - sink flow. using the fact that a similar strategy is used to enumerate all important separators of a given size, we merge this process with the flow - guided branching and show an fpt bound on the number of ( appropriately defined ) important multi - budgeted separators. this allows us to extend our algorithm to the skew multicut and directed feedback arc set problems. furthermore, we show connections of the multi - budgeted variants with weighted variants of the directed cut problems and the chain $ \ ell $ - sat problem, whose parameterized complexity remains an open problem. we show that these problems admit a bounded - in - parameter number of " maximally pushed " solutions ( in a similar spirit as important separators are maximally pushed ), giving somewhat weak evidence towards their tractability.
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arxiv:1810.06848
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in this paper we generalize the notion of the comparative index for the pair of lagrangian subspaces which has fundamental applications in oscillation theory of symplectic difference systems and linear differential hamiltonian systems. we introduce cyclic sums $ \ mu _ c ^ { \ pm } ( y _ 1, y _ 2, \ dots, y _ m ), \, m \ ge 2 $ of the comparative indices for the set of $ n - $ dimensional lagrangian subspaces. we formulate and prove main properties of the cyclic sums, in particular, we state connections of the cyclic sums with the kashiwara index. the main results of the paper connect the cyclic sums of the comparative indices with the number of positive and negative eigenvalues of $ mn \ times mn $ symmetric matrices defined in terms of the wronskians $ y _ i ^ t \, j \, y _ j, $ $ i, j = 1, \ dots, m. $ we also present first applications of the cyclic sums of the comparative indices in the oscillation theory of the discrete symplectic systems connecting the number of focal points of their principal solutions with the negative and positive inertia of symmetric matrices.
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arxiv:2202.01041
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we define generalised chiral vertex operators covariant under the ocneanu ` ` double triangle algebra ' ' { \ cal a }, a novel quantum symmetry intrinsic to a given rational 2 - d conformal field theory. this provides a chiral approach, which, unlike the conventional one, makes explicit various algebraic structures encountered previously in the study of these theories and of the associated critical lattice models, and thus allows their unified treatment. the triangular ocneanu cells, the 3j - symbols of the weak hopf algebra { \ cal a }, reappear in several guises. with { \ cal a } and its dual algebra { hat a } one associates a pair of graphs, g and { \ tilde g }. while g are known to encode complete sets of conformal boundary states, the ocneanu graphs { \ tilde g } classify twisted torus partition functions. the fusion algebra of the twist operators provides the data determining { \ hat a }. the study of bulk field correlators in the presence of twists reveals that the ocneanu graph quantum symmetry gives also an information on the field operator algebra.
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arxiv:hep-th/0101151
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convolutional neural networks ( cnn ) have enabled major advances in image classification through convolution and pooling. in particular, image pooling transforms a connected discrete grid into a reduced grid with the same connectivity and allows reduction functions to take into account all the pixels of an image. however, a pooling satisfying such properties does not exist for graphs. indeed, some methods are based on a vertex selection step which induces an important loss of information. other methods learn a fuzzy clustering of vertex sets which induces almost complete reduced graphs. we propose to overcome both problems using a new pooling method, named mivspool. this method is based on a selection of vertices called surviving vertices using a maximal independent vertex set ( mivs ) and an assignment of the remaining vertices to the survivors. consequently, our method does not discard any vertex information nor artificially increase the density of the graph. experimental results show an increase in accuracy for graph classification on various standard datasets.
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arxiv:2208.01648
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two - level systems ( tls ) coupled to waveguides are a fundamental paradigm for light - matter interactions and quantum networks. we introduce and experimentally demonstrate a method to tune the interaction between a tls, implemented as a flux qubit, and a transmission line waveguide from a decoupled state to a coupling strength that is a significant fraction of the tls transition frequency, near the ultra - strong coupling regime. the coupling, controlled via magnetic flux, is described by a normalized coupling strength $ \ alpha $ that is measured to range between $ 6. 2 \ times10 ^ { - 5 } $ and $ 2. 19 \ times10 ^ { - 2 } $, with larger attainable maximum values predicted by a circuit model of the device. this system enables future investigations in the dynamics of the spin - boson model, microwave photonics, and relativistic quantum information.
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arxiv:2208.05571
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mesh generation plays a crucial role in scientific computing. traditional mesh generation methods, such as tfi and pde - based methods, often struggle to achieve a balance between efficiency and mesh quality. to address this challenge, physics - informed intelligent learning methods have recently emerged, significantly improving generation efficiency while maintaining high mesh quality. however, physics - informed methods fail to generalize when applied to previously unseen geometries, as even small changes in the boundary shape necessitate burdensome retraining to adapt to new geometric variations. in this paper, we introduce meshonet, the first generalizable intelligent learning method for structured mesh generation. the method transforms the mesh generation task into an operator learning problem with multiple input and solution functions. to effectively overcome the multivariable mapping restriction of operator learning methods, we propose a dual - branch, shared - trunk architecture to approximate the mapping between function spaces based on input - output pairs. experimental results show that meshonet achieves a speedup of up to four orders of magnitude in generation efficiency over traditional methods. it also enables generalization to different geometries without retraining, greatly enhancing the practicality of intelligent methods.
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arxiv:2501.11937
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the ability to confine light into tiny spatial dimensions is important for applications such as microscopy, sensing and nanoscale lasers. while plasmons offer an appealing avenue to confine light, landau damping in metals imposes a trade - off between optical field confinement and losses. we show that a graphene - insulator - metal heterostructure can overcome that trade - off, and demonstrate plasmon confinement down to the ultimate limit of the lengthscale of one atom. this is achieved by far - field excitation of plasmon modes squeezed into an atomically thin hexagonal boron nitride dielectric h - bn spacer between graphene and metal rods. a theoretical model which takes into account the non - local optical response of both graphene and metal is used to describe the results. these ultra - confined plasmonic modes, addressed with far - field light excitation, enables a route to new regimes of ultra - strong light - matter interactions.
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arxiv:1804.01061
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let $ f $ be a nonarchimedean local field and consider the action of the reductive group so $ _ 3 ( f ) $ on the spherical variety ( u $ _ 3 $ / o $ _ 3 ) ( f ) $. we compute the endoscopic orbital integrals of the basic function in this situation. knowing the endoscopic orbital integrals is essential for observing the existence of transfer in this relative setting. this would be the first time such a computation has appeared in the literature for spherical varieties with type $ n $ - spherical roots.
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arxiv:2110.11890
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we investigate the impacts of spatial pricing for ride - sourcing services in a stackelberg framework considering traffic congestion. in the lower level, we use combined distribution and assignment approaches to explicitly capture the interactions between drivers ' relocation, riders ' mode choice, and all travelers ' routing decisions. in the upper level, a single transportation network company ( tnc ) determines spatial pricing strategies to minimize imbalance in a two - sided market. we show the existence of the optimal pricing strategies for locational imbalance minimization, and propose effective algorithms with reliable convergence properties. furthermore, the optimal pricing is unique and can be solved in a convex reformulation when matching time can be ignored. we conduct numerical experiments on different scales of transportation networks with different tnc objectives to generate policy insights on how spatial pricing could impact transportation systems.
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arxiv:2006.00164
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we propose a novel algorithm for learning fair representations that can simultaneously mitigate two notions of disparity among different demographic subgroups in the classification setting. two key components underpinning the design of our algorithm are balanced error rate and conditional alignment of representations. we show how these two components contribute to ensuring accuracy parity and equalized false - positive and false - negative rates across groups without impacting demographic parity. furthermore, we also demonstrate both in theory and on two real - world experiments that the proposed algorithm leads to a better utility - fairness trade - off on balanced datasets compared with existing algorithms on learning fair representations for classification.
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arxiv:1910.07162
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in this article, using hadamard product for $ _ 4f _ 3 \ left ( ^ { a _ 1, \, a _ 2, \, a _ 3, \, a _ 4 } _ { b _ 1, \, b _ 2, \, b _ 3 } ; z \ right ) $ hypergeometric function with normalized analytic functions in the open unit disc, an operator $ \ mathcal { i } ^ { a _ 1, a _ 2, a _ 3, a _ 4 } _ { b _ 1, b _ 2, b _ 3 } ( f ) ( z ) $ is introduced. geometric properties of $ _ 4f _ 3 \ left ( ^ { a _ 1, \, a _ 2, \, a _ 3, \, a _ 4 } _ { b _ 1, \, b _ 2, \, b _ 3 } ; z \ right ) $ hypergeometric functions are discussed for various subclasses of univalent functions. also, we consider an operator $ \ mathcal { i } ^ { a, \ frac { b } { 4 }, \ frac { b + 1 } { 4 }, \ frac { b + 2 } { 4 }, \ frac { b + 3 } { 4 } } _ { \ frac { c } { 4 }, \ frac { c + 1 } { 4 }, \ frac { c + 2 } { 4 }, \ frac { c + 3 } { 4 } } ( f ) ( z ) $ $ = z \, _ 5f _ 4 \ left ( ^ { a, \ frac { b } { 4 }, \ frac { b + 1 } { 4 }, \ frac { b + 2 } { 4 }, \ frac { b + 3 } { 4 } } _ { \ frac { c } { 4 }, \ frac { c + 1 } { 4 }, \ frac { c + 2 } { 4 }, \ frac { c + 3 } { 4 } } ; z \ right ) * f ( z ) $, where, $ _ 5f _ 4 ( z ) $ hypergeometric function and the $ * $ is usual hadamard product. in the main results, conditions are determined on $ a, b, $ and $ c $ such that the function $ z \, _ 5f _ 4 \
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arxiv:2211.04950
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we establish a link between the concepts of infrared renormalons, infrared fixed point, and dynamical nonperturbative mass generation of gluons in pure yang - mills theories. by utilizing recent results in the resurgent analysis of renormalons through non - linear ordinary differential equations, we develop a new description for the gluon propagator, thereby realizing the schwinger mechanism. specifically, this approach leads to a nonperturbative, dynamic mass generation for yang - mills gauge bosons in the deep infrared region, a phenomenon closely associated with color confinement. furthermore, we present arguments about the limit of applicability of the borel - ecalle resummation of the renormalons by comparing it with the kallen - lehman representation of the gluon propagator.
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arxiv:2405.01639
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in the first half of the paper, some recent advances in coupled dynamical systems, in particular, a globally coupled map are surveyed. first, dominance of milnor attractors in partially ordered phase is demonstrated. second, chaotic itinerancy in high - dimensional dynamical systems is briefly reviewed, with discussion on a possible connection with a milnor attractor network. third, infinite - dimensional collective dynamics is studied, in the thermodynamic limit of the globally coupled map, where bifurcation to lower - dimensional attractors by the addition of noise is briefly reviewed. following the study of coupled dynamical systems, a scenario for developmental process of cell society is proposed, based on numerical studies of a system with interacting units with internal dynamics and reproduction. differentiation of cell types is found as a natural consequence of such a system. " stem cells " that either proliferate or differentiate to different types generally appear in the system, where irreversible loss of multipotency is demonstrated. robustness of the developmental process against microscopic and macroscopic perturbations is found and explained, while irreversibility in developmental process is analyzed in terms of the gain of stability, loss of diversity and chaotic instability. construction of a phenomenology theory for development is discussed in comparison with the thermodynamics.
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arxiv:nlin/0203040
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a sixth order quadrupole boson hamiltonian is treated through a time dependent variational principle approach choosing as trial function a coherent state with respect to zeroth $ b ^ { \ dagger } _ 0 $ and second $ b ^ { \ dagger } _ 2 + b ^ { \ dagger } _ { - 2 } $ components of the quadrupole bosons. the coefficients involved in the model hamiltonian are chosen so that the classical effective potential energy term has two distinct minima. the equation of motion for the radial coordinate is analytically solved and the resulting trajectories are extensively studied. one distinguishes three energy regions exhibiting different types of trajectories. when one passes from the region characterized by two wells to the region of energies higher than the maximum value of the effective potential the trajectories period exhibits a singularity which reflects a phase transition. the classical trajectories are quantized by a constraint similar to the bohr - sommerfeld quantization condition. the semiclassical spectra corresponding to the two potential wells have specific properties. the tunneling process through the potential barrier is also studied. the transmission coefficients exhibit jumps in magnitude when the angular momentum acquires certain values.
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arxiv:nucl-th/0507069
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we present a novel method for the calculation of the static and electronic dielectric tensor of polar insulating crystals based on concepts from the modern theory of dielectric polarization. as an application, we present the first ab initio calculation of the dielectric constants in the wurtzite iii - v nitrides aln, gan, and inn.
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arxiv:cond-mat/9707252
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in this paper we obtain a 2 + 2 double null hamiltonian description of general relativity using only the ( complex ) so ( 3 ) connection and the components of the complex densitised self - dual bivectors. we carry out the general canonical analysis of this system and obtain the first class constraint algebra entirely in terms of the self - dual variables. the first class algebra forms a lie algebra and all the first class constraints have a simple geometrical interpretation.
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arxiv:gr-qc/0604084
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we present 1. 4 to 2. 5 um integral field spectroscopy of 16 stars in the braid nebula star formation region in cygnus ob7. these data forms one aspect of a large - scale multi - wavelength survey aimed at determining an unbiased estimate of the number, mass distribution, and evolutionary state of the young stars within this one square degree area of the previously poorly studied lynds 1003 molecular cloud. our new spectroscopic data, when combined with 2mass near - ir photometry, provide evidence of membership of many of these objects in the regions pre - main sequence population. we discuss both the characteristics of the young stars found in the region and the level of star forming activity present.
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arxiv:0810.3943
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we give a variant of the homogeneous buchberger algorithm for positively graded lattice ideals. using this algorithm we solve the sullivant computational commutative algebra challenge.
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arxiv:math/0508287
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we consider $ d = 2 $, $ \ mathcal { n } = ( 0, 2 ) $ scfts that can arise from m5 - branes wrapping four - dimensional, complex, toric manifolds and orbifolds. we use equivariant localization to compute the off - shell central charge of the dual supergravity solutions, obtaining a result which can be written as a sum of gravitational blocks and precisely agrees with a field theory computation using anomaly polynomials and $ c $ - extremization.
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arxiv:2308.10933
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far infrared fine structure line data from the iso archive have been extracted for several hundred ysos and their outflows, including molecular ( co ) outflows, optical jets and herbig - haro ( hh ) objects. given the importance of these lines to astrophysics, their excitation and transfer ought to be investigated in detail and, at this stage, the reliability of the diagnostic power of the fine structure transitions of o i and c ii has been examined. several issues, such as the extremely small intensity ratios of the oxygen 63 micron to 145 micron lines, are still awaiting an explanation. it is demonstrated that, in interstellar cloud conditions, the 145 micron line is prone to masing, but that this effect is likely an insufficient cause of the line ratio anomaly observed from cold dark clouds. very optically thick emission could in principle also account for this, but would need similar, prohibitively high column densities and must therefore be abondoned as a viable explanation. one is left with [ o i ] 63 micron self absorption by cold and tenuous foreground gas, as has been advocated for distant luminous sources. recent observations with the submillimeter observatory odin support this scenario also in the case of nearby dark molecular clouds. on the basis of this large statistical material we are led to conclude that in star forming regions, the [ o i ] and [ c ii ] lines generally have only limited diagnostic value.
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arxiv:astro-ph/0509836
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we report the results of deep ( 4. 6h ) h band spectroscopy of the well studied z ~ 12 h - band dropout galaxy candidate udfj - 39546284 with mosfire on keck - i. these data reach a sensitivity of 5 - 10 x 10 ^ - 19 erg s ^ - 1 cm ^ - 2 per 4. 4 angstrom resolution element between sky lines. previous papers have argued this source could either be a large equivalent width line emitting galaxy at 2 < z < 3. 5 or a luminous galaxy at z ~ 12. we find a 2. 2 sigma peak associated with a line candidate in deep hubble - space - telescope wide - field - camera 3 infrared grism observations, but at a lower flux than what was expected. after considering several possibilities we conclude these data can not conclusively confirm or reject the previous line detection, and significantly deeper spectroscopic observations are required. we also search for low - redshift emission lines in ten other 7 < z < 10 z, y, and j - dropout candidates in our mask and find no significant detections.
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arxiv:1307.4089
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a complete numerical description of the charge and spin dynamics of a two - electron system confined in narrow nanowire quantum dots under oscillating electric field is presented in the context of recent electric dipole spin resonance experiments. we find that the spin - orbit coupling results in lifting the spin blockade by phonon mediated relaxation provided that the initially occupied state is close in energy to the ground state. this leads to suppression of the blockade from the triplet state with spins polarized parallel to the external magnetic field b. at higher b, after singlet - triplet ground - state transition a new channel for lifting the pauli blockade opens which results in an appearance of additional resonance lines. the calculated signatures of this transition are consistent with recent experimental results [ s. m. frolov et al., phys. rev. lett. 109, 236805 ( 2012 ) ].
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arxiv:1303.0211
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there has been considerable interest in a recent preprint - arxiv / 1407. 3194 - describing an effect named as the quantum pigeonhole principle. the classical pigeonhole principle ( classical php ) refers to a result in number theory which states that if n objects are distributed between m boxes, with m less than n, then at least one box must contain more than one object. an experiment is proposed in the preprint where interactions between particles would reveal that they were in the same box, but a quantum mechanical measurement would imply that no more than 1 of the n objects is contained in any of the m boxes, even though n is greater than m. this result has been greeted by the authors of the preprint and some others as being of great importance in the understanding of quantum mechanics. in this paper we show by a full quantum mechanical treatment that the effect appears to arise as a result of interference between the components of the wavefunctions, each of which is subject to the classical php.
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arxiv:1412.1333
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we develop an automated computational modeling framework for rapid gradient - based design of multistable soft mechanical structures composed of non - identical bistable unit cells with appropriate geometric parameterization. this framework includes a custom isogeometric analysis - based continuum mechanics solver that is robust and end - to - end differentiable, which enables geometric and material optimization to achieve a desired multistability pattern. we apply this numerical modeling approach in two dimensions to design a variety of multistable structures, accounting for various geometric and material constraints. our framework demonstrates consistent agreement with experimental results, and robust performance in designing for multistability, which facilities soft actuator design with high precision and reliability.
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arxiv:2309.04970
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the prospects of the future panda experiment at fair in darmstadt / germany in the field of charmonium and charm spectroscopy are discussed.
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arxiv:1210.4701
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a ccd photometry of the dwarf nova master ot j172758. 09 + 380021. 5 was carried out in 2019 during 134 nights. observations covered three superoutbursts, five normal outbursts and quiescence between them. the available asassn and ztf data for 2014 - 2020 were also examined. spectral observations were done in 2020 when the object was in quiescence. spectra and photometry revealed that the star is an h - rich active er uma - type dwarf nova with a highly variable supercycle of ~ 50 - 100 d that implies a high and variable mass - transfer rate. this object demonstrated peculiar behaviour : short - lasted superoutbursts ( a week ) ; a slow superoutburst decline and cases of rebrightenings ; low frequency ( from none to a few ) of the normal outbursts during the supercycle. in 2019 a mean period of positive superhumps was found to be 0. 05829 d during the superoutbursts. late superhumps with a mean period of 0. 057915 d which lasted about ~ 20 d after the end of superoutburst and were replaced by an orbital period of 0. 057026 d or its orbital - negative superhump beat period were detected. an absence of eclipse in the orbital light curve and its moderate amplitude are consistent with the orbital inclination of about 40 degr found from spectroscopy. the blue peaks of the v - ic and b - rc of superhumps during the superoutburst coincided with minima of the light curves, while b - rc of the late superhumps coincided with a rising branch of the light curves. we found that a low mass ratio q = 0. 08 could explain most of the peculiarities of this dwarf nova. the mass - transfer rate should be accordingly higher than what is expected from gravitational radiation only, this assumes the object is in a post - nova state and underwent a nova eruption relatively recently - - hundreds of years ago. this object would provide probably the first observational evidence that a nova eruption can occur even in cvs near the period minimum.
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arxiv:2103.14369
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recent studies on reservoir computing essentially involve a high dimensional dynamical system as the reservoir, which transforms and stores the input as a higher dimensional state, for temporal and nontemporal data processing. we demonstrate here a method to predict temporal and nontemporal tasks by constructing virtual nodes as constituting a reservoir in reservoir computing using a nonlinear map, namely the logistic map, and a simple finite trigonometric series. we predict three nonlinear systems, namely lorenz, rossler, and hindmarsh - rose, for temporal tasks and a seventh order polynomial for nontemporal tasks with great accuracy. also, the prediction is made in the presence of noise and found to closely agree with the target. remarkably, the logistic map performs well and predicts close to the actual or target values. the low values of the root mean square error confirm the accuracy of this method in terms of efficiency. our approach removes the necessity of continuous dynamical systems for constructing the reservoir in reservoir computing. moreover, the accurate prediction for the three different nonlinear systems suggests that this method can be considered a general one and can be applied to predict many systems. finally, we show that the method also accurately anticipates the time series of the all the three variable of rossler system for the future ( self prediction ).
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arxiv:2401.09501
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we point out that the mixed - event method for two - particle acceptance correction, widely used in particle correlation measurements at rhic and lhc, is wrong in cases where the single particle pseudorapidity distribution is significantly nonuniform. the correct acceptance should be the convolution of two single - particle efficiency $ \ times $ acceptance functions. the error of the mixed - event method, which guarantees a uniform $ \ delta \ eta $ two - particle combinatorial density, is, however, small in correlation analyses where the two particles are integrated over an extended pseudorapidity $ \ eta $ range. with one particle fixed in $ \ eta $ and the right acceptance correction, the background - subtracted correlated pair density may reveal not only a short - range but also a long - range $ \ delta \ eta $ dependence. this has important physics implication, and may provide crucial information to disentangle physics mechanisms for the recently observed long - range ridge correlation in asymmetric proton - lead collisions at the lhc.
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arxiv:1304.8120
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we study the perturbative dynamics of noncommutative field theories on r ^ d, and find an intriguing mixing of the uv and the ir. high energies of virtual particles in loops produce non - analyticity at low momentum. consequently, the low energy effective action is singular at zero momentum even when the original noncommutative field theory is massive. some of the nonplanar diagrams of these theories are divergent, but we interpret these divergences as ir divergences and deal with them accordingly. we explain how this uv / ir mixing arises from the underlying noncommutativity. this phenomenon is reminiscent of the channel duality of the double twist diagram in open string theory.
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arxiv:hep-th/9912072
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unit disk graphs are intersection graphs of circles of unit radius in the plane. we present simple and provably good heuristics for a number of classical np - hard optimization problems on unit disk graphs. the problems considered include maximum independent set, minimum vertex cover, minimum coloring and minimum dominating set. we also present an on - line coloring heuristic which achieves a competitive ratio of 6 for unit disk graphs. our heuristics do not need a geometric representation of unit disk graphs. geometric representations are used only in establishing the performance guarantees of the heuristics. several of our approximation algorithms can be extended to intersection graphs of circles of arbitrary radii in the plane, intersection graphs of regular polygons, and to intersection graphs of higher dimensional regular objects.
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arxiv:math/9409226
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the hotelling game consists of n servers each choosing a point on the line segment, so as to maximize the amount of clients it attracts. clients are uniformly distributed along the line, and each client buys from the closest server. in this paper, we study a fault - prone version of the hotelling game, where the line fails at multiple random locations. each failure disconnects the line, blocking the passage of clients. we show that the game admits a nash equilibrium if and only if the rate of faults exceeds a certain threshold, and calculate that threshold approximately. moreover, when a nash equilibrium exists we show it is unique and construct it explicitly. hence, somewhat surprisingly, the potential occurrence of failures has a stabilizing effect on the game ( provided there are enough of them ). additionally, we study the social cost of the game ( measured in terms of the total transportation cost of the clients ), which also seems to benefit in a certain sense from the potential presence of failures.
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arxiv:1907.06602
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fractional evolution equations lack generally accessible and well - converged codes excepting anomalous diffusion. a particular equation of strong interest to the growing intersection of applied mathematics and quantum information science and technology is the fractional schr \ " odinger equation, which describes sub - and super - dispersive behavior of quantum wavefunctions induced by multiscale media. we derive a computationally efficient sixth - order split - step numerical method to converge the eigenfunctions of the fse to arbitrary numerical precision for arbitrary fractional order derivative. we demonstrate applications of this code to machine precision for classic quantum problems such as the finite well and harmonic oscillator, which take surprising twists due to the non - local nature of the fractional derivative. for example, the evanescent wave tails in the finite well take a mittag - leffer - like form which decay much slower than the well - known exponential from integer - order derivative wave theories, enhancing penetration into the barrier and therefore quantum tunneling rates. we call this effect \ emph { fractionally enhanced quantum tunneling }. this work includes an open source code for communities from quantum experimentalists to applied mathematicians to easily and efficiently explore the solutions of the fractional schr \ " odinger equation in a wide variety of practical potentials for potential realization in quantum tunneling enhancement and other quantum applications.
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arxiv:2403.07233
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we propose elliptic power and power parameterizations for the probability distribution of initial state anisotropies in heavy - ion collisions. by assuming a linear eccentricity scaling, the new parameterizations can also be applied to fluctuations of harmonic flow. in particular, we analyze flow multi - particle cumulants and event - by - event distributions, both of which are recently measured at the lhc.
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arxiv:1408.0709
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to obtain a better understanding of the trade - offs between various objectives, bi - objective integer programming ( boip ) algorithms calculate the set of all non - dominated vectors and present these as the solution to a boip problem. historically, these algorithms have been compared in terms of the number of single - objective ips solved and total cpu time taken to produce the solution to a problem. this is equitable, as researchers can often have access to widely differing amounts of computing power. however, the real world has recently seen a large uptake of multi - core processors in computers, laptops, tablets and even mobile phones. with this in mind, we look at how to best utilise parallel processing to improve the elapsed time of optimisation algorithms. we present two methods of parallelising the recursive algorithm presented by ozlen, burton and macrae. both new methods utilise two threads and improve running times. one of the new methods, the meeting algorithm, halves running time to achieve near - perfect parallelisation. the results are compared with the efficiency of parallelisation within the commercial ip solver ibm ilog cplex, and the new methods are both shown to perform better.
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arxiv:1701.08920
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the milky way galaxy glows with the soft gamma ray emission resulting from the annihilation of $ \ sim 5 \ times 10 ^ { 43 } $ electron - positron pairs every second. the origin of this vast quantity of antimatter and the peculiar morphology of the 511kev gamma ray line resulting from this annihilation have been the subject of debate for almost half a century. most obvious positron sources are associated with star forming regions and cannot explain the rate of positron annihilation in the galactic bulge, which last saw star formation some $ 10 \, \ mathrm { gyr } $ ago, or else violate stringent constraints on the positron injection energy. radioactive decay of elements formed in core collapse supernovae ( ccsne ) and normal type ia supernovae ( sne ia ) could supply positrons matching the injection energy constraints but the distribution of such potential sources does not replicate the required morphology. we show that a single class of peculiar thermonuclear supernova - sn1991bg - like supernovae ( sne 91bg ) - can supply the number and distribution of positrons we see annihilating in the galaxy through the decay of $ ^ { 44 } $ ti synthesised in these events. such $ ^ { 44 } $ ti production simultaneously addresses the observed abundance of $ ^ { 44 } $ ca, the $ ^ { 44 } $ ti decay product, in solar system material.
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arxiv:1609.04893
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in classical matrix theory, there exist useful extremal characterizations of eigenvalues and their sums for hermitian matrices ( due to ky fan, courant - fischer - weyl and wielandt ) and some consequences such as the majorization assertion in lidskii ' s theorem. in this paper, we extend these results to the context of self adjoint elements of finite von neumann algebras, and their distribution and quantile functions. this work was motivated by a lemma in a paper by voiculescu and bercovici, that described such an extremal characterization of the distribution of a self - adjoint operator affiliated to a finite von neumann algebra - suggesting a possible analogue of the classical courant - fischer - weyl minmax theorem, for a self adjoint operator in a finite von neumann algebra. it is to be noted that the only von neumann algebras considered here have separable pre - duals.
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arxiv:1210.7581
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diffusion limited aggregation is studied from the perspective of computational complexity. a parallel algorithm is exhibited that requires a number of steps that scales as the depth of the tree defined by the cluster. the existence of this algorithm suggests a connection between a fundamental computational and structural property of dla.
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arxiv:cond-mat/0309519
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using a three - dimensional nonlinear hydrodynamic code, we examine the dynamical stability of more than twenty self - gravitating, compressible, ellipsoidal fluid configurations that initially have the same velocity structure as riemann s - type ellipsoids. our focus is on ` ` adjoint ' ' configurations, in which internal fluid motions dominate over the collective spin of the ellipsoidal figure ; dedekind - like configurations are among this group. we find that, although some models are stable and some are moderately unstable, the majority are violently unstable toward the development of $ m = 1 $, $ m = 3 $, and higher - order azimuthal distortions that destroy the coherent, $ m = 2 $ bar - like structure of the initial ellipsoidal configuration on a dynamical time scale. the parameter regime over which our models are found to be unstable generally corresponds with the regime over which incompressible riemann s - type ellipsoids have been found to be susceptible to an elliptical strain instability \ citep { ll96 }. we therefore suspect that an elliptical instability is responsible for the destruction of our compressible analogs of riemann ellipsoids. the existence of the elliptical instability raises concerns regarding the final fate of neutron stars that encounter the secular bar - mode instability and regarding the spectrum of gravitational waves that will be radiated from such systems.
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arxiv:astro-ph/0702750
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it is known that lorentz covariance fixes uniquely the current and the associated guidance law in the trajectory interpretation of quantum mechanics for spin particles. in the non - relativistic domain this implies a guidance law for the electron which differs by an additional spin - dependent term from that originally proposed by de broglie and bohm. in this paper we explore some of the implications of the modified guidance law. we bring out a property of mutual dependence in the particle coordinates that arises in product states, and show that the quantum potential has scalar and vector components which implies the particle is subject to a lorentz - like force. the conditions for the classical limit and the limit of negligible spin are given, and the empirical sufficiency of the model is demonstrated. we then present a series of calculations of the trajectories based on two - dimensional gaussian wave packets which illustrate how the additional spin - dependent term plays a significant role in structuring both the individual trajectories and the ensemble. the single packet corresponds to quantum inertial motion. the distinct features encountered when the wavefunction is a product or a superposition are explored, and the trajectories that model the two - slit experiment are given. the latter paths exhibit several new characteristics compared with the original de broglie - bohm ones, such as crossing of the axis of symmetry.
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arxiv:quant-ph/0302076
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the nonlinear component of the optomechanical interaction between light and mechanical vibration promises many exciting classical and quantum mechanical applications, but is generally weak. here we demonstrate enhancement of nonlinear optomechanical measurement of mechanical motion by using pairs of coupled optical and mechanical modes in a photonic crystal device. in the same device we show linear optomechanical measurement with a strongly reduced input power and reveal how both enhancements are related. our design exploits anisotropic mechanical elasticity to create strong coupling between mechanical modes while not changing optical properties. additional thermo - optic tuning of the optical modes is performed with an auxiliary laser and a thermally - optimised device design. we envision broad use of this enhancement scheme in multimode phonon lasing, two - phonon heralding and eventually nonlinear quantum optomechanics.
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arxiv:2207.11114
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it is shown that q - deformed quantum mechanics ( q - deformed heisenberg algebra ) can be interpreted as quantum mechanics on kaehler manifolds, or as a quantum theory with second ( or first - ) class constraints. ( saclay, t93 / 027 ).
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arxiv:hep-th/9403042
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the semi - classical study of the integer quantum hall conductivity is investigated for electrons in a bi - periodic potential $ v ( x, y ) $. the hall conductivity is due to the tunnelling effect and we concentrate our study to potentials having three wells in a periodic cell. a non - zero topological conductivity requires special conditions for the positions, and shapes of the wells. the results are derived analytically and well confirmed by numerical calculations.
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arxiv:cond-mat/9805086
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an electrostatic lens with three focusing elements in an alternating - gradient configuration is used to focus a fountain of cesium atoms in their ground ( strong - field - seeking ) state. the lens electrodes are shaped to produce only sextupole plus dipole equipotentials which avoids adding the unnecessary nonlinear forces present in cylindrical lenses. defocusing between lenses is greatly reduced by having all of the main electric fields point in the same direction and be of nearly equal magnitude. the addition of the third lens gave us better control of the focusing strength in the two transverse planes and allowed focusing of the beam to half the image size in both planes. the beam envelope was calculated for lens voltages selected to produced specific focusing properties. the calculations, starting from first principles, were compared with measured beam sizes and found to be in good agreement. application to fountain experiments, atomic clocks, and focusing polar molecules in strong - field - seeking states is discussed.
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arxiv:physics/0603127
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these are the proceedings of the international workshop on " nuclear dynamics with effective field theories " held at ruhr - universitaet bochum, germany from july 1 to 3, 2013. the workshop focused on effective field theories of low - energy qcd, chiral perturbation theory for nuclear forces as well as few - and many - body physics. included are a short contribution per talk.
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arxiv:1309.5820
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the direct geodesic problem on an oblate spheroid is described as an initial value problem and is solved numerically in geodetic and cartesian coordinates. the geodesic equations are formulated by means of the theory of differential geometry. the initial value problem under consideration is reduced to a system of first - order ordinary differential equations, which is solved using a numerical method. the solution provides the coordinates and the azimuths at any point along the geodesic. the clairaut constant is not assumed known but it is computed, allowing to check the precision of the method. an extended data set of geodesics is used, in order to evaluate the performance of the method in each coordinate system. the results for the direct geodesic problem are validated by comparison to karney ' s method. we conclude that a complete, stable, precise, accurate and fast solution of the problem in cartesian coordinates is accomplished.
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arxiv:1612.01357
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ocean ecosystems have spatiotemporal variability and dynamic complexity that require a long - term deployment of an autonomous underwater vehicle for data collection. a new long - range autonomous underwater vehicle called tethys is adapted to study different oceanic phenomena. additionally, an ocean environment has external forces and moments along with changing water currents which are generally not considered in a vehicle kinematic model. in this scenario, it is not enough to generate a simple trajectory from an initial location to a goal location in an uncertain ocean as the vehicle can deviate from its intended trajectory. as such, we propose to compute a feedback plan that adapts the vehicle trajectory in the presence of any modeled or unmodeled uncertainties. in this work, we present a feedback motion planning method for the tethys vehicle by combining a predictive ocean model and its kinematic modeling. given a goal location, the tethys kinematic model, and the water flow pattern, our method computes a feedback plan for the vehicle in a dynamic ocean environment that reduces its energy consumption. the computed feedback plan provides the optimal action for the tethys vehicle to take from any location of the environment to reach the goal location considering its orientation. our results based on actual ocean model prediction data demonstrate the applicability of our method.
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arxiv:1911.09581
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we introduce a multimodel approach to solve coupled cluster equations, employing a quasi newton algorithm for the ground state and an olsen algorithm for the excited states. in these algorithms, both of which can be viewed as newton algorithms, the jacobian matrix of a lower level coupled cluster model is used in newton equations associated with the target model. improvements in convergence then implies savings for sufficiently large molecular systems, since the computational cost of macroiterations scales more steeply with system size than the cost of microiterations. the multimodel approach is suitable when there is a lower level jacobian matrix that is much more accurate than the zeroth order approximation. applying the approach to the cc3 equations, using the ccsd approximation of the jacobian, we show that the time spent to determine the ground and valence excited states can be significantly reduced. we also find improved convergence for core excited states, indicating that similar savings will be obtained with an explicit implementation of the core - valence separated ccsd jacobian transformation.
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arxiv:2004.07773
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advancing llm reasoning skills has captivated wide interest. however, current post - training techniques rely heavily on supervisory signals, such as outcome supervision or auxiliary reward models, which face the problem of scalability and high annotation costs. this motivates us to enhance llm reasoning without the need for external supervision. we introduce a generalizable and purely unsupervised self - training framework, named genius. without external auxiliary, genius requires to seek the optimal response sequence in a stepwise manner and optimize the llm. to explore the potential steps and exploit the optimal ones, genius introduces a stepwise foresight re - sampling strategy to sample and estimate the step value by simulating future outcomes. further, we recognize that the unsupervised setting inevitably induces the intrinsic noise and uncertainty. to provide a robust optimization, we propose an advantage - calibrated optimization ( aco ) loss function to mitigate estimation inconsistencies. combining these techniques together, genius provides an advanced initial step towards self - improve llm reasoning with general queries and without supervision, revolutionizing reasoning scaling laws given the vast availability of general queries. the code will be released at https : / / github. com / xufangzhi / genius.
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arxiv:2504.08672
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two - dimensional van der waals janus materials and their heterostructures offer fertile platforms for designing fascinating functionalities. here, by means of systematic first - principles studies on van der waals janus monolayer cr - based dichalcogenide halides cryx ( y = s, se, te ; x = cl, br, i ), we find that crsx ( x = cl, br, i ) are the very desirable high tc ferromagnetic semiconductors with an out - of - plane magnetization. excitingly, by the benefit of the large magnetic moments on ligand s2 - anions, the sought - after large - gap quantum anomalous hall effect and sizable valley splitting can be achieved through the magnetic proximity effect in van der waals heterostructures crsbr / bi2se3 / crsbr and mote2 / crsbr, respectively. additionally, we show that large dzyaloshinskii - moriya interactions give rise to skyrmion states in crtex ( x = cl, br, i ) under external magnetic fields. our work reveals that two - dimensional janus magnet cr - based dichalcogenide halides have appealing multifunctionalities in the applications of topological electronic and valleytronic devices.
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arxiv:2205.04053
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this contribution describes the reorientation of the magnetization of thin ferromagnetic heisenberg films as function of the temperature and / or an external field. working in a rotating frame allows an exact treatment of the single - ion anisotropy when going to higher - order green ' s functions. terms due to the exchange interaction are treated by a generalized tyablikov ( rpa ) decoupling.
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arxiv:cond-mat/0605331
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in decentralized cloud computing marketplaces, ensuring fair and efficient interactions among asset providers and end - users is crucial. a key concern is meeting agreed - upon service - level objectives like the service ' s reliability. in this decentralized context, traditional mechanisms often fail to address the complexity of task failures, due to limited available and trustworthy insights into these independent actors ' individual behavior. this paper proposes a collective incentive mechanism that blindly punishes all involved parties when a task fails. based on ruin theory, we show that collective incentives improve behavior in the marketplace by creating a disincentive for faults and misbehavior even when the parties at fault are unknown, in turn leading to a more robust marketplace. simulations for small and large pools of marketplace assets show that collective incentives enable to meet or exceed a reliability target, i. e., the success - rate of tasks run using marketplace assets, by eventually discarding failure - prone assets while preserving reliable ones.
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arxiv:2503.19055
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we study $ ads _ 5 \ times \ sigma _ 2 $ and $ ads _ 4 \ times \ sigma _ 3 $ solutions of $ n = 2 $, $ so ( 4 ) $ gauged supergravity in seven dimensions with $ \ sigma _ { 2, 3 } $ being $ s ^ { 2, 3 } $ or $ h ^ { 2, 3 } $. the $ so ( 4 ) $ gauged supergravity is obtained from coupling three vector multiplets to the pure $ n = 2 $, $ su ( 2 ) $ gauged supergravity. with a topological mass term for the 3 - form field, the $ so ( 4 ) \ sim su ( 2 ) \ times su ( 2 ) $ gauged supergravity admits two supersymmetric $ ads _ 7 $ critical points, with $ so ( 4 ) $ and $ so ( 3 ) $ symmetries, provided that the two $ su ( 2 ) $ gauge couplings are different. these vacua correspond to $ n = ( 1, 0 ) $ superconformal field theories ( scfts ) in six dimensions. in the case of $ \ sigma _ 2 $, we find a class of $ ads _ 5 \ times s ^ 2 $ and $ ads _ 5 \ times h ^ 2 $ solutions preserving eight supercharges and $ so ( 2 ) \ times so ( 2 ) $ symmetry, but only $ ads _ 5 \ times h ^ 2 $ solutions exist for $ so ( 2 ) $ symmetry. these should correspond to some $ n = 1 $ four - dimensional scfts. we also give rg flow solutions from the $ n = ( 1, 0 ) $ scfts in six dimensions to these four - dimensional fixed points including a two - step flow from the $ so ( 4 ) $ $ n = ( 1, 0 ) $ scft to the $ so ( 3 ) $ $ n = ( 1, 0 ) $ scft that eventually flows to the $ n = 1 $ scft in four dimensions. for $ ads _ 4 \ times \ sigma _ 3 $, we find a class of $ ads _ 4 \ times s ^ 3 $ and $ ads _ 4 \ times h ^ 3 $ solutions with four supercharges, corresponding to $ n = 1 $ scfts in three dimensions. when the two $ su ( 2 ) $ gauge couplings are equal, only $ ads _ 4 \ times h ^ 3 $ are
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arxiv:1503.04997
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we consider probabilistic multinomial probit classification using gaussian process ( gp ) priors. the challenges with the multiclass gp classification are the integration over the non - gaussian posterior distribution, and the increase of the number of unknown latent variables as the number of target classes grows. expectation propagation ( ep ) has proven to be a very accurate method for approximate inference but the existing ep approaches for the multinomial probit gp classification rely on numerical quadratures or independence assumptions between the latent values from different classes to facilitate the computations. in this paper, we propose a novel nested ep approach which does not require numerical quadratures, and approximates accurately all between - class posterior dependencies of the latent values, but still scales linearly in the number of classes. the predictive accuracy of the nested ep approach is compared to laplace, variational bayes, and markov chain monte carlo ( mcmc ) approximations with various benchmark data sets. in the experiments nested ep was the most consistent method with respect to mcmc sampling, but the differences between the compared methods were small if only the classification accuracy is concerned.
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arxiv:1207.3649
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in two - dimensional dilaton gravity theories, there may exist a global weyl invariance which makes black hole spurious. if the global invariance and the local weyl invariance of the matter coupling are intact at the quantum level, there is no hawking radiation. we explicitly verify the absence of anomalies in these symmetries for the model proposed by callan, giddings, harvey and strominger. the crucial observation is that the conformal anomaly can be cohomologically trivial and so not truly anomalous in such dilaton gravity models.
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arxiv:hep-th/9308095
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verifiers that can prove programs correct against their full functional specification require, for programs with loops, additional annotations in the form of loop invariants - - - propeties that hold for every iteration of a loop. we show that significant loop invariant candidates can be generated by systematically mutating postconditions ; then, dynamic checking ( based on automatically generated tests ) weeds out invalid candidates, and static checking selects provably valid ones. we present a framework that automatically applies these techniques to support a program prover, paving the way for fully automatic verification without manually written loop invariants : applied to 28 methods ( including 39 different loops ) from various java. util classes ( occasionally modified to avoid using java features not fully supported by the static checker ), our dynamate prototype automatically discharged 97 % of all proof obligations, resulting in automatic complete correctness proofs of 25 out of the 28 methods - - - outperforming several state - of - the - art tools for fully automatic verification.
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arxiv:1407.5286
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this paper investigates the optimal formation control problem of a class of nonlinear multi - agent systems ( mass ) under denial - of - service ( dos ) attacks. we design the optimal formation control law using an event - triggered control scheme to achieve formation objectives under dos attacks. critic neural network ( nn ) - based approach is employed to achieve the optimal control policy under dos attacks. event - triggered mechanism is introduced to ensure the saving of control resources. additionally, lyapunov stability theory is utilized to demonstrate that the local neighborhood formation error exhibits exponential stability and the estimation error of weights are uniformly ultimately bounded. finally, the effectiveness of the control algorithm is validated through matlab simulations. the results indicate that under dos attacks, the nonlinear mas successfully achieves the desired formation for the mas.
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arxiv:2504.14874
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impulse formulations of the euler ( and navier - stokes ) equations were considered by kuz ' min [ 1 ] and oseledets [ 2 ] and different impulse formulations are produced by various gauge transformations ( russo and smereka [ 3 ] ). the extension of the kuz ' min - oseledets formulation to the compressible, barotropic case was considered by tur and yanovsky [ 4 ] and shivamoggi [ 5 ]. here, we construct exact solutions for the fluid impulse density for incompressible and compressible barotropic flows and discuss their physical signifcance.
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arxiv:1812.09294
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high dimensional quantum entanglement and the advancements in their experimental realization provide a playground for fundamental research and eventually lead to quantum technological developments. the horodecki criterion determines whether a state violates clauser - horne - shimony - holt ( chsh ) inequality for a two - qubit entangled state, solely from the state parameters. however, it remains a challenging task to formulate similar necessary and sufficient criteria for a high - dimensional entangled state for the violation of a suitable bell inequality. here, we develop a horodecki - like criterion based on the state parameters of arbitrary two - qudit states to violate a two - outcome bell inequality involving $ 2 ^ { n - 1 } $ and $ n $ measurement settings for alice and bob, respectively. this inequality reduces to the well - known chsh and gisin ' s elegant bell inequalities for $ n = 2 $ and $ n = 3 $, respectively. while the proposed criterion is sufficient to violate the bell inequality, it becomes necessary as well for the following cases ; ( i ) $ m $ copies of bell diagonal states for arbitrary $ n $, ( ii ) non - decomposable states whose correlation matrix is diagonalized by local unitaries, and ( iii ) for any arbitrary two - qubit state when $ n = 3 $, where the maximal value of the bell functional is achieved with bob ' s measurements being pairwise anticommuting. for any states, we derive the constraints on alice ' s measurements in achieving the maximum quantum violation for this inequality.
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arxiv:2408.10350
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we study the reward - free reinforcement learning framework, which is particularly suitable for batch reinforcement learning and scenarios where one needs policies for multiple reward functions. this framework has two phases. in the exploration phase, the agent collects trajectories by interacting with the environment without using any reward signal. in the planning phase, the agent needs to return a near - optimal policy for arbitrary reward functions. we give a new efficient algorithm, \ textbf { s } taged \ textbf { s } ampling + \ textbf { t } runcated \ textbf { p } lanning ( \ algoname ), which interacts with the environment at most $ o \ left ( \ frac { s ^ 2a } { \ epsilon ^ 2 } \ text { poly } \ log \ left ( \ frac { sah } { \ epsilon } \ right ) \ right ) $ episodes in the exploration phase, and guarantees to output a near - optimal policy for arbitrary reward functions in the planning phase. here, $ s $ is the size of state space, $ a $ is the size of action space, $ h $ is the planning horizon, and $ \ epsilon $ is the target accuracy relative to the total reward. notably, our sample complexity scales only \ emph { logarithmically } with $ h $, in contrast to all existing results which scale \ emph { polynomially } with $ h $. furthermore, this bound matches the minimax lower bound $ \ omega \ left ( \ frac { s ^ 2a } { \ epsilon ^ 2 } \ right ) $ up to logarithmic factors. our results rely on three new techniques : 1 ) a new sufficient condition for the dataset to plan for an $ \ epsilon $ - suboptimal policy ; 2 ) a new way to plan efficiently under the proposed condition using soft - truncated planning ; 3 ) constructing extended mdp to maximize the truncated accumulative rewards efficiently.
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arxiv:2010.05901
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the innovative application of precise geospatial vegetation forecasting holds immense potential across diverse sectors, including agriculture, forestry, humanitarian aid, and carbon accounting. to leverage the vast availability of satellite imagery for this task, various works have applied deep neural networks for predicting multispectral images in photorealistic quality. however, the important area of vegetation dynamics has not been thoroughly explored. our study breaks new ground by introducing greenearthnet, the first dataset specifically designed for high - resolution vegetation forecasting, and contextformer, a novel deep learning approach for predicting vegetation greenness from sentinel 2 satellite images with fine resolution across europe. our multi - modal transformer model contextformer leverages spatial context through a vision backbone and predicts the temporal dynamics on local context patches incorporating meteorological time series in a parameter - efficient manner. the greenearthnet dataset features a learned cloud mask and an appropriate evaluation scheme for vegetation modeling. it also maintains compatibility with the existing satellite imagery forecasting dataset earthnet2021, enabling cross - dataset model comparisons. our extensive qualitative and quantitative analyses reveal that our methods outperform a broad range of baseline techniques. this includes surpassing previous state - of - the - art models on earthnet2021, as well as adapted models from time series forecasting and video prediction. to the best of our knowledge, this work presents the first models for continental - scale vegetation modeling at fine resolution able to capture anomalies beyond the seasonal cycle, thereby paving the way for predicting vegetation health and behaviour in response to climate variability and extremes.
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arxiv:2303.16198
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neural metamorphosis ( neumeta ) is a recent paradigm for generating neural networks of varying width and depth. based on implicit neural representation ( inr ), neumeta learns a continuous weight manifold, enabling the direct generation of compressed models, including those with configurations not seen during training. while promising, the original formulation of neumeta proves effective only for the final layers of the undelying model, limiting its broader applicability. in this work, we propose a training algorithm that extends the capabilities of neumeta to enable full - network metamorphosis with minimal accuracy degradation. our approach follows a structured recipe comprising block - wise incremental training, inr initialization, and strategies for replacing batch normalization. the resulting metamorphic networks maintain competitive accuracy across a wide range of compression ratios, offering a scalable solution for adaptable and efficient deployment of deep models. the code is available at : https : / / github. com / tsommariva / htty _ neumeta.
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arxiv:2505.05510
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we provide new representations for the finite parts at the poles and the derivative at zero of the barnes zeta function in any dimension in the general case. these representations are in the forms of series and limits. we also give an integral representation for the finite parts at the poles. similar results are derived for an associated function, which we term homogeneous barnes zeta function. our expressions immediately yield analogous representations for the logarithm of the barnes gamma function, including the particular case also known as multiple gamma function.
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arxiv:1703.04817
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malicious document files used in targeted attacks often contain a small program called shellcode. it is often hard to prepare a runnable environment for dynamic analysis of these document files because they exploit specific vulnerabilities. in these cases, it is necessary to identify the position of the shellcode in each document file to analyze it. if the exploit code uses executable scripts such as javascript and flash, it is not so hard to locate the shellcode. on the other hand, it is sometimes almost impossible to locate the shellcode when it does not contain any javascript or flash but consists of native x86 code only. binary fragment classification is often applied to visualize the location of regions of interest, and shellcode must contain at least a small fragment of x86 native code even if most of it is obfuscated, such as, a decoder for the obfuscated body of the shellcode. in this paper, we propose a novel method, o - glasses, to visualize the shellcode by recognizing the x86 native code using a specially designed one - dimensional convolutional neural network ( 1d - cnn ). the fragment size needs to be as small as the minimum size of the x86 native code in the whole shellcode. our results show that a 16 - instruction - sequence ( approximately 48 bytes on average ) is sufficient for the code fragment visualization. our method, o - glasses ( 1d - cnn ), outperforms other methods in that it recognizes x86 native code with a surprisingly high f - measure rate ( about 99. 95 % ).
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arxiv:1806.05328
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the 17o ( p, g ) 18f reaction plays an important role in hydrogen burning processes in different stages of stellar evolution. the rate of this reaction must therefore be known with high accuracy in order to provide the necessary input for astrophysical models. the cross section of 17o ( p, g ) 18f is characterized by a complicated resonance structure at low energies. experimental data, however, is scarce in a wide energy range which increases the uncertainty of the low energy extrapolations. the purpose of the present work is therefore to provide consistent and precise cross section values in a wide energy range. the cross section is measured using the activation method which provides directly the total cross section. with this technique some typical systematic uncertainties encountered in in - beam gamma - spectroscopy experiments can be avoided. the cross section was measured between 500 kev and 1. 8 mev proton energies with a total uncertainty of typically 10 %. the results are compared with earlier measurements and it is found that the gross features of the 17o ( p, g ) 18f excitation function is relatively well reproduced by the present data. deviation of roughly a factor of 1. 5 is found in the case of the total cross section when compared with the only one high energy dataset. at the lowest measured energy our result is in agreement with two recent datasets within one standard deviation and deviates by roughly two standard deviations from a third one. an r - matrix analysis of the present and previous data strengthen the reliability of the extrapolated zero energy astrophysical s - factor. using an independent experimental technique, the literature cross section data of 17o ( p, g ) 18f is confirmed in the energy region of the resonances while lower direct capture cross section is recommended at higher energies. the present dataset provides a constraint for the theoretical cross sections.
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arxiv:1703.03184
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although deep learning has made remarkable progress in processing various types of data such as images, text and speech, they are known to be susceptible to adversarial perturbations : perturbations specifically designed and added to the input to make the target model produce erroneous output. most of the existing studies on generating adversarial perturbations attempt to perturb the entire input indiscriminately. in this paper, we propose exploreadv, a general and flexible adversarial attack system that is capable of modeling regional and imperceptible attacks, allowing users to explore various kinds of adversarial examples as needed. we adapt and combine two existing boundary attack methods, deepfool and brendel \ & bethge attack, and propose a mask - constrained adversarial attack system, which generates minimal adversarial perturbations under the pixel - level constraints, namely ` ` mask - constraints ' '. we study different ways of generating such mask - constraints considering the variance and importance of the input features, and show that our adversarial attack system offers users good flexibility to focus on sub - regions of inputs, explore imperceptible perturbations and understand the vulnerability of pixels / regions to adversarial attacks. we demonstrate our system to be effective based on extensive experiments and user study.
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arxiv:2301.01223
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we show that the perturbation series for quarkonia energies diverges at large orders. this results in a perturbative ambiguity in the energy that scales as e ^ ( - 1 / a * lambda ) where a is the bohr radius of quarkonium and lambda is the qcd scale parameter. this ambiguity is associated with a nonperturbative contribution to the energy from distances of order 1 / lambda and greater. this contribution is separate from that of the gluon condensate.
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arxiv:hep-ph/9707525
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lattice qcd indicates a large amount of entropy associated with the heavy quark - antiquark pair immersed in the quark - gluon plasma. this entropy grows as a function of the inter - quark distance giving rise to an entropic force that can be very effective in dissociating the bound quarkonium states. in addition, the lattice data show a very sharp peak in the heavy quark - antiquark entropy at the deconfinement transition. since the quark - gluon plasma around the deconfinement transition is strongly coupled, we employ the holographic correspondence to study the entropy associated with the heavy quark - antiquark pair in two theories : i ) $ { \ cal { n } } = 4 $ supersymmetric yang - mills and ii ) a confining yang - mills theory obtained by compactification on a kaluza - klein circle. in both cases we find the entropy growing with the inter - quark distance and evaluate the effect of the corresponding entropic forces. in the case ii ), we find a sharp peak in the entropy near the deconfinement transition, in agreement with the lattice qcd results. this peak in our holographic description arises because the heavy quark pair acts as an eyewitness of the black hole formation in the bulk - - the process that describes the deconfinement transition. in terms of the boundary theory, this entropy likely emerges from the entanglement of a " long string " connecting the quark and antiquark with the rest of the system.
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arxiv:1411.0618
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extended version of lectures given at the university of karlsruhe and at calc - 2000 school in dubna. properties of hqet as a field theory, methods of calculation of hqet diagrams and some simple applications are explained in detail. these lectures can be used as an additional chapter with any modern qcd textbook.
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arxiv:hep-ph/0008300
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we present numerical evidence that most two - dimensional surface states of a bulk topological superconductor ( tsc ) sit at an integer quantum hall plateau transition. we study tsc surface states in class ci with quenched disorder. low - energy ( finite - energy ) surface states were expected to be critically delocalized ( anderson localized ). we confirm the low - energy picture, but find instead that finite - energy states are also delocalized, with universal statistics that are independent of the tsc winding number, and consistent with the spin quantum hall plateau transition ( percolation ).
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arxiv:1711.03972
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motivated by the ability to consistently apply the ryu - takayanagi prescription for general convex surfaces and the relationship between entanglement and geometry in tensor networks, we introduce a novel, covariant bulk object - the holographic slice. the holographic slice is found by considering the continual removal of short range information in a boundary state. it thus provides a natural interpretation as the bulk dual of a series of coarse - grained holographic states. the slice possesses many desirable properties that provide consistency checks for its boundary interpretation. these include monotonicity of both area and entanglement entropy, uniqueness, and the inability to probe beyond late - time black hole horizons. additionally, the holographic slice illuminates physics behind entanglement shadows, as minimal area extremal surfaces anchored to a coarse - grained boundary may probe entanglement shadows. this lets the slice flow through shadows. to aid in developing intuition for these slices, many explicit examples of holographic slices are investigated. finally, the relationship to tensor networks and renormalization ( particularly in ads / cft ) is discussed.
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arxiv:1805.00523
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accurate gait event detection is crucial for gait analysis, rehabilitation, and assistive technology, particularly in exoskeleton control, where precise identification of stance and swing phases is essential. this study evaluated the performance of seven kinematics - based methods and a long short - term memory ( lstm ) model for detecting heel strike and toe - off events across 4363 gait cycles from 588 able - bodied subjects. the results indicated that while the zeni et al. method achieved the highest accuracy among kinematics - based approaches, other methods exhibited systematic biases or required dataset - specific tuning. the lstm model performed comparably to zeni et al., providing a data - driven alternative without systematic bias. these findings highlight the potential of deep learning - based approaches for gait event detection while emphasizing the need for further validation in clinical populations and across diverse gait conditions. future research will explore the generalizability of these methods in pathological populations, such as individuals with post - stroke conditions and knee osteoarthritis, as well as their robustness across varied gait conditions and data collection settings to enhance their applicability in rehabilitation and exoskeleton control.
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arxiv:2503.00794
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we study the implications for generating the cosmological baryon asymmetry through leptogenesis in the recent model of fileviez perez and wise, which provides a new mechanism for generating neutrino masses at one - loop by introducing new color octet fermion and scalar fields. we find that there are significant differences with respect to other models for leptogenesis : low scale leptogenesis can occur naturally and the cp asymmetry can be large as there is no upper bound arising from neutrino masses. the cp asymmetry is insensitive to the phases in the neutrino mixing matrix. we investigate in detail the minimal model that can simultaneously fit low scale neutrino physics, the $ \ mu \ to e \ gamma $ bound and leptogenesis. the model can provide outstanding collider signatures and the value of the cp - asymmetry can be more constrained from lepton flavour violating processes than from neutrino physics.
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arxiv:0909.0648
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we study scenarios where loop processes give the dominant contributions to dark matter decay or annihilation despite the presence of tree level channels. we illustrate this possibility in a specific model where dark matter is part of a hidden sector that communicates with the standard model sector via a heavy neutrino portal. we explain the underpinning rationale for how loop processes mediated by the portal neutrinos can parametrically dominate over tree level decay channels, and demonstrate that this qualitatively changes the indirect detection signals in positrons, neutrinos, and gamma rays.
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arxiv:1912.05581
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using an operator approach based on a commutator scheme that has been previously applied to richardson ' s reduced bcs model and the inhomogeneous dicke model, we obtain general exact solvability requirements for an anisotropic central spin model with $ xxz $ - type hyperfine coupling between the central spin and the spin bath, without any prior knowledge of integrability of the model. we outline the basic steps of the usage of the operator approach, and pedagogically summarize them into two \ emph { lemmas } and two \ emph { constraints }. through a step - by - step construction of the eigen - problem, we show that the condition $ g ' ^ 2 _ j - g _ j ^ 2 = c $ naturally arises for the model to be exactly solvable, where $ c $ is a constant independent of the bath - spin index $ j $, and $ \ { g _ j \ } $ and $ \ { g ' _ j \ } $ are the longitudinal and transverse hyperfine interactions, respectively. the obtained conditions and the resulting bethe ansatz equations are consistent with that in previous literature.
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arxiv:1802.06490
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the origin of atmospheric heating in the cool, magnetic white dwarf gd 356 remains unsolved nearly 40 years after its discovery. this once idiosyncratic star with $ t _ { \ rm eff } \ approx7500 $ k, yet balmer lines in zeeman - split emission is now part of a growing class of white dwarfs exhibiting similar features, and which are tightly clustered in the hr diagram suggesting an intrinsic power source. this paper proposes that convective motions associated with an internal dynamo can power electric currents along magnetic field lines that heat the atmosphere via ohmic dissipation. such currents would require a dynamo driven by core $ ^ { 22 } $ ne distillation, and would further corroborate magnetic field generation in white dwarfs by this process. the model predicts that the heating will be highest near the magnetic poles, and virtually absent toward the equator, in agreement with observations. this picture is also consistent with the absence of x - ray or extreme ultraviolet emission, because the resistivity would decrease by several orders of magnitude at the typical coronal temperatures. the proposed model suggests that i ) dahe stars are mergers with enhanced $ ^ { 22 } $ ne that enables distillation and may result in significant cooling delays ; and ii ) any mergers that distill neon will generate magnetism and chromospheres. the predicted chromospheric emission is consistent with the two known massive dqe white dwarfs.
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arxiv:2407.19289
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we develop a new approach to the representation theory of quantum algebras supporting a torus action via methods from the theory of finite - state automata and algebraic combinatorics. we show that for a fixed number $ m $, the torus - invariant primitive ideals in $ m \ times n $ quantum matrices can be seen as a regular language in a natural way. using this description and a semigroup approach to the set of cauchon diagrams, a combinatorial object that paramaterizes the primes that are torus - invariant, we show that for $ m $ fixed, the number of torus - invariant primitive ideals in $ m \ times n $ quantum matrices satisfies a linear recurrence in $ n $ over the rational numbers. in the $ 3 \ times n $ case we give a concrete description of the torus - invariant primitive ideals and use this description to give an explicit formula for the number p ( 3, n ).
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arxiv:0901.4707
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the study of high - redshift objects is rapidly developing, allowing to build the star formation history of the universe. since most of the flux from starbursts comes out in the fir region, the submm and mm are privileged domains for the exploration at high z. i review the recent work on galaxies at high redshift in this wavelength region, for the continuum as well as for the line detection ( dust and molecular gas ). perspectives are discussed to detect early objects ( maybe protogalaxies ) with the future large millimeter instruments.
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arxiv:astro-ph/9909016
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a canonical lorentz invariant field theory extension of collective field theory of d = 1 matrix models is presented. we show that the low density, discrete, sector of collective field theory includes single eigenvalue euclidean instantons which tunnel between different vacua of the extended theory. these " stringy " instantons induce non - perturbative effective operators of strength $ e ^ { - { 1 / g } } $. the relationship of the world sheet description of string theory and liouville theory to the effective space - time theory is explained.
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arxiv:hep-th/9209045
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revisiting pca for time series reduction in temporal dimension ; jiaxin gao, wenbo hu, yuntian chen ; deep learning has significantly advanced time series analysis ( tsa ), enabling the extraction of complex patterns for tasks like classification, forecasting, and regression. although dimensionality reduction has traditionally focused on the variable space - achieving notable success in minimizing data redundancy and computational complexity - less attention has been paid to reducing the temporal dimension. in this study, we revisit principal component analysis ( pca ), a classical dimensionality reduction technique, to explore its utility in temporal dimension reduction for time series data. it is generally thought that applying pca to the temporal dimension would disrupt temporal dependencies, leading to limited exploration in this area. however, our theoretical analysis and extensive experiments demonstrate that applying pca to sliding series windows not only maintains model performance, but also enhances computational efficiency. in auto - regressive forecasting, the temporal structure is partially preserved through windowing, and pca is applied within these windows to denoise the time series while retaining their statistical information. by preprocessing time - series data with pca, we reduce the temporal dimensionality before feeding it into tsa models such as linear, transformer, cnn, and rnn architectures. this approach accelerates training and inference and reduces resource consumption. notably, pca improves informer training and inference speed by up to 40 % and decreases gpu memory usage of timesnet by 30 %, without sacrificing model accuracy. comparative analysis against other reduction methods further highlights the effectiveness of pca in improving the efficiency of tsa models.
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arxiv:2412.19423
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visco - energetic solutions have been recently advanced as a new solution concept for rate - independent systems, alternative to energetic solutions / quasistatic evolutions and balanced viscosity solutions. in the spirit of this novel concept, we revisit the analysis of the variational model proposed by francfort and marigo for the quasi - static crack growth in brittle materials, in the case of antiplane shear. in this context, visco - energetic solutions can be constructed by perturbing the time incremental scheme for quasistatic evolutions by means of a viscous correction inspired by the term introduced by almgren, taylor, and wang in the study of mean curvature flows. with our main result we prove the existence of a visco - energetic solution with a given initial crack. we also show that, if the cracks have a finite number of tips evolving smoothly on a given time interval, visco - energetic solutions comply with griffith ' s criterion.
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arxiv:2105.00046
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hall coefficient $ r _ h $ and thermoelectric power tep are studied systematically in the single crystals $ nd _ { 2 - x } ce _ xcuo _ { 4 + \ delta } $ ( ncco ) with different x from underdoped to overdoped regime. with increasing doping level, both $ r _ h $ and tep decrease and change their sign from negative to positive. a striking feature is that the temperature dependence of the hall angle follows a $ t ^ 4 $ behavior in the underdoped regime, while a $ t ^ 2 $ in the overdoped regime. these behaviors are closely related to the evolution of fermi surface with doping level observed by arpes.
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arxiv:cond-mat/0506681
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human - created engines and evolutionarily optimized molecular motors exhibit sophisticated design in order to harvest chemical or thermal energy for generating unidirectional motion. the complexity of these motors makes their random emergence unlikely. molecules capable of locomotion, however, seem to be essential to the creation of the first self - replicator and initiation of darwinian evolution, posing a question of the physical mechanism that can facilitate emergence of directed motion in an isotropic environment. here we show a universal thermodynamic mechanism for spontaneous emergence of motor abilities in a mechanical system. a non - equilibrium system with multiple degrees of freedom develops symmetry breaking that favors rectification of environmental thermal fluctuations. the corresponding velocities and its fluctuations are calculated. homochirality of living matter is explained as chirality breaking resulting from the emergence of a motor. universality of the results provides a general extension of the onsager relations to the non - linear regime.
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arxiv:1605.09142
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we perform a comparative study between the only radio detected type i superluminous supernova ( slsn ) ptf10hgi, and the most active repeating fast radio burst frb121102. this study has its root in the hypothesized frb - slsn connection that states that magnetars born in slsn can power frbs. the wideband spectrum ( 0. 6 - - 15 ghz ) of ptf10hgi presented here, provides strong evidence for the magnetar wind nebular origin of the radio emission. the same spectrum also enables us to make robust estimates of the radius and the magnetic field of the radio emitting region and demonstrates that the nebula is powered by the rotational energy of the magnetar. this spectrum is then compared with that of frb121102 which we extend down to 400 mhz using archival data. the newly added measurements put very tight constraint on the emission models of the compact persistent source associated with frb121102. we find that while both sources can be powered by the rotational energy of the underlying magnetar, the average energy injection rate is much higher in frb121102. hence, we hypothesise that, if ptf10hgi is indeed emitting fast radio bursts, those will be much weaker energetically than those from frb121102.
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arxiv:2008.11375
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optimal transport ( ot ) is being widely used in various fields such as machine learning and computer vision, as it is a powerful tool for measuring the similarity between probability distributions and histograms. in previous studies, ot has been defined as the minimum cost to transport probability mass from one probability distribution to another. in this study, we propose a new framework in which ot is considered as a maximum a posteriori ( map ) solution of a probabilistic generative model. with the proposed framework, we show that ot with entropic regularization is equivalent to maximizing a posterior probability of a probabilistic model called collective graphical model ( cgm ), which describes aggregated statistics of multiple samples generated from a graphical model. interpreting ot as a map solution of a cgm has the following two advantages : ( i ) we can calculate the discrepancy between noisy histograms by modeling noise distributions. since various distributions can be used for noise modeling, it is possible to select the noise distribution flexibly to suit the situation. ( ii ) we can construct a new method for interpolation between histograms, which is an important application of ot. the proposed method allows for intuitive modeling based on the probabilistic interpretations, and a simple and efficient estimation algorithm is available. experiments using synthetic and real - world spatio - temporal population datasets show the effectiveness of the proposed interpolation method.
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arxiv:2006.08866
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the spectral features of hd 94509 are highly unusual, adding an extreme to the zoo of be and shell stars. the shell dominates the spectrum, showing lines typical for spectral types mid - a to early - f, while the presence of a late / mid b - type central star is indicated by photospheric hydrogen line wings and helium lines. numerous metallic absorption lines have broad wings but taper to narrow cores. they cannot be fit by voigt profiles. we aim to describe and illustrate unusual spectral features of this star, and make rough calculations to estimate physical conditions and abundances in the shell. furthermore, the central star is characterized. we assume mean conditions for the shell. an electron density estimate is made from the inglis - teller formula. excitation temperatures and column densities for fe i and fe ii are derived from curves of growth. the neutral h column density is estimated from high paschen members. the column densities are compared with calculations made with the photoionization code cloudy. atmospheric parameters of the central star are constrained employing non - lte spectrum synthesis. overall chemical abundances are close to solar. column densities of the dominant ions of several elements, as well as excitation temperatures and the mean electron density are well accounted for by a simple model. several features, including the degree of ionization, are less well described. hd 94509 is a be star with a stable shell, close to the terminal - age main sequence. the dynamical state of the shell and the unusually shaped, but symmetric line profiles, require a separate study.
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arxiv:1503.08317
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we study the volume averaging of inhomogeneous metrics within gr and discuss its shortcomings such as gauge dependence, singular behavior as a result of caustics, and causality violations. to remedy these shortcomings, we suggest some modifications to this method. as a case study we focus on the inhomogeneous structured frw model based on a flat ltb metric. the effect of averaging is then studied in terms of an effective backreaction fluid. it is shown that, contrary to the claims in the literature, the backreaction fluid behaves like a dark matter component, instead of dark energy, having a density of the order of 10 ^ { - 5 } times the matter density, and most importantly, it is gauge dependent.
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arxiv:0709.2558
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we prove a contact non - squeezing result for a class of embeddings between starshaped domains in the contactization of the symplectization of the unit cotangent bundle of certain manifolds. the class of embeddings includes embeddings which are not isotopic to the identity. this yields a new proof that there is no positive loop of contactomorphisms in the unit cotangent bundles under consideration. the proof uses the shape invariant introduced by sikorav and eliashberg.
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arxiv:2212.13352
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in order to explore electric - field - induced transformations of polarization singularities in the polarization - resolved angular ( conoscopic ) patterns emerging after deformed helix ferroelectric liquid crystal ( dhflc ) cells with subwavelength helix pitch, we combine the transfer matrix formalism with the results for the effective dielectric tensor of biaxial flcs evaluated using an improved technique of averaging over distorted helical structures. within the framework of the transfer matrix method, we deduce a number of symmetry relations and show that the symmetry axis of l lines ( curves of linear polarization ) is directed along the major in - plane optical axis which rotates under the action of the electric field. when the angle between this axis and the polarization plane of incident linearly polarized light is above its critical value, the c points ( points of circular polarization ) appear in the form of symmetrically arranged chains of densely packed star - monstar pairs. we also emphasize the role of phase singularities of a different kind and discuss the enhanced electro - optic response of dhflcs near the exceptional point where the condition of zero - field isotropy is fulfilled.
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arxiv:1407.3534
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we study a semiclassical inverse spectral problem based on a spectral asymptotics result of arxiv : math / 0502032, which applies to small non - selfadjoint perturbations of selfadjoint $ h $ - pseudodifferential operators in dimension 2. the eigenvalues in a suitable complex window have an expansion in terms of a quantum birkhoff normal form for the operator near several lagrangian tori which are invariant under the classical dynamics and satisfy a diophantine condition. in this work we prove that the normal form near a single diophantine torus is uniquely determined by the associated eigenvalues. we also discuss the normalization procedure and symmetries of the quantum birkhoff normal form near a diophantine torus.
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arxiv:1001.5132
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we address in this review unified analysis of phase - field models for cohesive fracture. aiming to regularize the barenblatt ( 1959 ) cohesive zone model, all the discussed models are distinguished by three characteristic functions, i. e., the geometric function dictating the crack profile, the degradation function for the constitutive relation and the dissipation function defining the crack driving force. the latter two functions coincide in the associated formulation, while in the non - associated one they are designed to be different. distinct from the counterpart for brittle fracture, in the phase - field model for cohesive fracture the regularization length parameter has to be properly incorporated into the dissipation and / or degradation functions such that the failure strength and traction - separation softening curve are both well - defined. moreover, the resulting crack bandwidth needs to be non - decreasing during failure in order that imposition of the crack irreversibility condition does not affect the anticipated traction - separation law ( tsl ). with a truncated degradation function that is proportional to the length parameter, the conti et al. ( 2016 ) model and the latter improved versions can deal with crack nucleation only in the vanishing limit and capture cohesive fracture only with a particular tsl. owing to a length scale dependent degradation function of rational fraction, these deficiencies are largely overcome in the phase - field cohesive zone model ( pf - czm ). among many variants in the literature, only with the optimal geometric function, can the associated pf - czm apply to general non - concave softening laws and the non - associated upf - czm to ( almost ) any arbitrary one. some mis - interpretations are clarified and representative numerical examples are presented.
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arxiv:2412.03836
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in the second edition of the congruence lattice book, problem 22. 1 asks for a characterization of subsets $ q $ of a finite distributive lattice $ d $ such that there is a finite lattice $ l $ whose congruence lattice is isomorphic to $ d $ and under this isomorphism $ q $ corresponds the the principal congruences of $ l $. in this note, we prove some preliminary results.
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arxiv:1705.05319
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we present the notion of non - abelian descent type, which classifies torsors up to twisting by a galois cocycle. this relies on the previous construction of kernels and non - abelian galois 2 - cohomology due to springer and borovoi. the necessity of descent types arises in the context of the descent theory where no torsors are given a priori, for example, when we wish to study the arithmetic properties such as the brauer - - manin obstruction to the hasse principle on homogeneous spaces without rational points. this new definition also unifies the types by colliot - th \ ' el \ ` ene - - sansuc, the extended types by harari - - skorobogatov, and the finite descent type by harpaz - - wittenberg.
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arxiv:2401.00340
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in order to perform faster simulations, the model reduction is nowadays used in industrial contexts to solve large and complex problems. however, the efficiency of such an approach is sometimes cut by the interface size of the reduced model and its reusability. in this article, we focus on the development of a reduction methodology for the build of modal analysis oriented and updatable reduced order model whose size is not linked to their contacting interface. in order to allow latter model readjusting, we impose the use of eigenmodes in the reduction basis. eventually, the method introduced is coupled to an arnoldi based enrichment algorithm in order to improve the accuracy of the reduced model produced. in the last section the proposed methodology is discussed and compared to the craig and bampton reduction method. during this comparison we observed that even when not enriched, our work enables us to recover the craig and bampton accuracy with partially updatable and smaller reduced order model.
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arxiv:1903.02943
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a new state of the h $ _ 2 ^ + $ molecular ion with binding energy of 1. 09 $ \ times10 ^ { - 9 } $ a. u. below the first dissociation limit is predicted, using highly accurate numerical nonrelativistic quantum calculations. it is the first l = 0 excited state, antisymmetric with respect to the exchange of the two protons. it manifests itself as a huge p - h scattering length of $ a = 750 \ pm 5 $ bohr radii.
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arxiv:physics/0207007
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events = = 22 june – the royal observatory greenwich will celebrate its 350th anniversary. september – nasa will launch its pandora mission, which aims to observe 20 stars and their 39 exoplanets. = = = date unknown = = = nasa ' s imap probe will launch toward lagrange point 1 to collect interstellar dust and investigate space weather. the vera c. rubin observatory is expected to begin science operations in late 2025. science - related budgets us : various details about planned science - related spending for 2025 have been described with some information on the planned research subjects or areas. = = see also = = category : science events category : science timelines list of emerging technologies list of years in science = = references = = = = external links = = media related to 2025 in science at wikimedia commons
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https://en.wikipedia.org/wiki/2025_in_science
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extended 21cm absorption regions ( dubbed ` ` 21cm absorption halos ' ' ) around first galaxies at $ z \ sim 30 $ are likely the first distinctive structures accessible to radio observations. though the radio array capable of detecting and resolving them must have $ \ sim 200 $ km $ ^ 2 $ total collecting area, given the great impact of such detections to the understanding of the reionization process and cosmology, such radio survey would be extremely profitable. as an example, we point out a potentially useful byproduct of such survey. the resolved 21cm absorption ` ` halos ' ', likely close to spherical, can serve as ( almost ) ideal sources for measuring the { \ it cosmic shear } and mapping the matter distribution to $ z \ sim 30 $. we investigate the expected lensing signal and consider a variety of noise contributions on the shear measurement. we find that s / n $ \ sim 1 $ can be achieved for individual ` ` halos ' '. given millions of 21cm absorption ` ` halos ' ' across the sky, the total s / n will be comparable to traditional shear measurement of $ \ sim $ $ 10 ^ 9 $ galaxies at $ z \ sim 1 $.
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arxiv:astro-ph/0608271
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we show that the sigma models with target spaces supersymmetric heterotic backgrounds with $ su ( 2 ) $ and $ su ( 3 ) $ holonomy are invariant under a w - symmetry algebra generated by the covariantly constant forms of these backgrounds. the closure of the w - algebra requires additional generators which we identify. we prove that the chiral anomalies of all these symmetries are consistent at one - loop in perturbation theory. we also demonstrate that these anomalies cancel at the same loop level either by adding suitable finite local counterterms in the sigma model effective action or by assuming a plausible quantum correction to the transformations. such a correction is compatible with both the cancellation mechanism for spacetime frame rotation and gauge transformation anomalies, and the correction to the heterotic supergravity up to two loops in the sigma model perturbation theory.
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arxiv:2305.19793
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