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the symmetry properties of the cooper pairing problem for multi - component ultra - cold dipolar molecular systems are investigated. the dipolar anisotropy provides a natural and robust mechanism for both triplet and singlet cooper pairing to first order in the interaction strength. with a purely dipolar interaction, the triplet $ p _ z $ - like polar pairing is the most dominant. a short - range attractive interaction can enhance the singlet pairing to be nearly degenerate with the triplet pairing. we point out that these two pairing channels can mix by developing a relative phase of $ \ pm \ frac { \ pi } { 2 } $, thus spontaneously breaking time - reversal symmetry. we also suggest the possibility of such mixing of triplet and singlet pairing in other systems.
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arxiv:0910.4940
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we present a fast and portable re - implementation of piskunov and valenti ' s optimal - extraction algorithm ( piskunov & valenti, 2002 } in c / c + + together with full uncertainty propagation, improved cosmic - ray removal, and an optimal background - subtraction algorithm. this re - implementation can be used with iraf and most existing data - reduction packages and leads to signal - to - noise ratios close to the poisson limit. the algorithm is very stable, operates on spectra from a wide range of instruments ( slit spectra and fibre feeds ), and has been extensively tested for vlt / uves, eso / ces, eso / feros, ntt / emmi, not / alfosc, stella / ses, sso / wifes, and finally, p60 / sedm - ifu data.
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arxiv:1311.4755
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we find a new class of exact solutions of the five - dimensional einstein equations whose corresponding four - dimensional spacetime possesses a schwarzschild - like behavior. the electromagnetic potential depends on a harmonic function and can be choosen to be of a monopole, dipole, etc. field. the solutions are asymptotically flat and for vanishing magnetic field the four metrics are of the schwarzschild solution. the spacetime is singular in $ r = 2m $ for higher multipole moments, but regular for monopoles or vanishing magnetic fields in this point. the scalar field posseses a singular behavior. # ( preprint cinvestav 15 / 93 ) #
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arxiv:gr-qc/9402008
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in this work, we examine seven systems discovered by tess, to see whether there is any room in those systems for an additional planet ( or several ) to lurk unseen between the two planets already confirmed therein. in five of those systems ( namely hd 15337 ; hd 21749 ; hd 63433 ; hd 73583 and ltt 3780 ) we find that there is ample room for an undiscovered planet to move between those that have already been discovered. in other words, as they currently stand, those systems are not tightly packed. in stark contrast, the perturbative influence of the two known toi - 1670 planets is such that additional planets in between are ruled out. the final system, toi 421, is more challenging. in the vast majority of cases, adding an earth - mass planet to that system between the orbits of the known planets caused catastrophic instability. just ~ 1. 1 % of our simulations of the modified system proved dynamically stable on a timescale of one million years. as a result, it seems that there is very little room between the two known planets in the toi 421 system for an addition unseen world to exist, but the existence of such a planet can not be definitely ruled out on dynamical grounds alone.
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arxiv:2411.00245
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engineering to create a pathogen which specifically kills women. another of herbert ' s creations, the dune series of novels, uses genetic engineering to create the powerful tleilaxu. few films have informed audiences about genetic engineering, with the exception of the 1978 the boys from brazil and the 1993 jurassic park, both of which make use of a lesson, a demonstration, and a clip of scientific film. genetic engineering methods are weakly represented in film ; michael clark, writing for the wellcome trust, calls the portrayal of genetic engineering and biotechnology " seriously distorted " in films such as the 6th day. in clark ' s view, the biotechnology is typically " given fantastic but visually arresting forms " while the science is either relegated to the background or fictionalised to suit a young audience. = = see also = = biological engineering computational genomics modifications ( genetics ) mutagenesis ( molecular biology technique ) = = references = = = = further reading = = = = external links = = gmo safety - information about research projects on the biological safety of genetically modified plants. gmo - compass, news on gmo en eu
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https://en.wikipedia.org/wiki/Genetic_engineering
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it is now widely recognized that ontologies, are one of the fundamental cornerstones of knowledge - based systems. what is lacking, however, is a currently accepted strategy of how to build ontology ; what kinds of the resources and techniques are indispensables to optimize the expenses and the time on the one hand and the amplitude, the completeness, the robustness of en ontology on the other hand. the paper offers a semi - automatic ontology construction method from text corpora in the domain of radiological protection. this method is composed from next steps : 1 ) text annotation with part - of - speech tags ; 2 ) revelation of the significant linguistic structures and forming the templates ; 3 ) search of text fragments corresponding to these templates ; 4 ) basic ontology instantiation process
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arxiv:1405.1346
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in this paper we provide the classification of positive solutions to the critical $ p - $ laplace equation on $ \ mathbb { r } ^ n $, for $ 1 < p < n $, possibly having infinite energy. if $ n = 2 $, or if $ n = 3 $ and $ \ frac 32 < p < 2 $ we prove rigidity without any further assumptions. in the remaining cases we obtain the classification under energy growth conditions or suitable control of the solutions at infinity. our assumptions are much weaker than those already appearing in the literature. we also discuss the extension of the results to the riemannian setting.
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arxiv:2204.06940
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we investigate the effect of a coupling between dark matter and dark energy on the rates for the direct detection of dark matter. the magnitude of the effect depends on the strength $ \ kappa $ of this new interaction relative to gravity. the resulting isothermal velocity distribution for dark matter in galaxy halos is still maxwell - boltzmann ( m - b ), but the characteristic velocity and the escape velocity are increased by $ \ sqrt { 1 + \ kappa ^ 2 } $. we adopt a phenomenological approach and consider values of $ \ kappa $ near unity. for such values we find that : ( i ) the ( time averaged ) event rate increases for light wimps, while it is somewhat reduced for wimp masses larger than 100 gev. ( ii ) the time dependence of the rate arising from the modulation amplitude is decreased compared to the standard m - b velocity distribution. ( iii ) the average and maximum wimp energy increase proportionally to $ 1 + \ kappa ^ 2 $, which, for sufficiently massive wimps, allows the possibility of designing experiments measuring $ \ gamma $ rays following nuclear de - excitation.
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arxiv:hep-ph/0609078
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one of the more popular objections towards shape dynamics is the suspicion that anomalies in the spatial weyl symmetry will arise upon quantization. the purpose of this short paper is to establish the tools required for an investigation of the sort of anomalies that can possibly arise. the first step is to adapt to our setting barnich and henneaux ' s formulation of gauge cohomology in the hamiltonian setting, which serve to decompose the anomaly into a spatial component and time component. the spatial part of the anomaly, i. e. the anomaly in the symmetry algebra itself ( $ [ \ omega, \ omega ] \ propto \ hbar $ instead of vanishing ) is given by a projection of the second ghost cohomology of the hamiltonian brst differential associated to $ \ omega $, modulo spatial derivatives. the temporal part, $ [ \ omega, h ] \ propto \ hbar $ is given by a different projection of the first ghost cohomology and an extra piece arising from a solution to a functional differential equation. assuming locality of the gauge cohomology groups involved, this part is always local. assuming locality for the gauge cohomology groups, using barnich and henneaux ' s results, the classification of weyl cohomology for higher ghost numbers performed by boulanger, and following the descent equations, we find a complete characterizations of anomalies in 3 + 1 dimensions. the spatial part of the anomaly and the first component of the temporal anomaly are always local given these assumptions even in shape dynamics. the part emerging from the solution of the functional differential equations explicitly involves the shape dynamics hamiltonian, and thus might be non - local. if one restricts this extra piece of the temporal anomaly to be also local, then overall no \ emph { local } weyl anomalies, either temporal or spatial, emerge in the 3 + 1 case.
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arxiv:1309.1119
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in this paper, we build the hamiltonian system and the corresponding lax pairs associated to a twisted connection in $ \ mathfrak { gl } _ 2 ( \ mathbb { c } ) $ admitting an irregular and ramified pole at infinity of arbitrary degree, hence corresponding to the painlev \ ' { e } $ 1 $ hierarchy. we provide explicit formulas for these lax pairs and hamiltonians in terms of the irregular times and standard $ 2g $ darboux coordinates associated to the twisted connection. furthermore, we obtain a map that reduces the space of irregular times to only $ g $ non - trivial isomonodromic deformations. in addition, we perform a symplectic change of darboux coordinates to obtain a set of symmetric darboux coordinates in which hamiltonians and lax pairs are polynomial. finally, we apply our general theory to the first cases of the hierarchy : the airy case $ ( g = 0 ) $, the painlev \ ' { e } $ 1 $ case $ ( g = 1 ) $ and the next two elements of the painlev \ ' { e } $ 1 $ hierarchy.
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arxiv:2302.13905
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shortcuts to adiabaticity have been proposed to speed up the " slow " adiabatic transport of an atom or a wave packet of atoms. however, the freedom of the inverse engineering approach with appropriate boundary conditions provides thousands of trap trajectories for different purposes, for example, time and energy minimizations. in this paper, we propose trigonometric protocols for fast and robust atomic transport, taking into account cubic or quartic anharmonicities. the numerical results have illustrated that such trigonometric protocols, particular cosine ansatz, is more robust and the corresponding final energy excitation is smaller, as compared to sine trajectories implemented in previous experiments.
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arxiv:1705.06523
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the adoption of cyber - physical systems ( cps ) is on the rise in complex physical environments, encompassing domains such as autonomous vehicles, the internet of things ( iot ), and smart cities. a critical attribute of cps is robustness, denoting its capacity to operate safely despite potential disruptions and uncertainties in the operating environment. this paper proposes a novel specification - based robustness, which characterizes the effectiveness of a controller in meeting a specified system requirement, articulated through signal temporal logic ( stl ) while accounting for possible deviations in the system. this paper also proposes the robustness falsification problem based on the definition, which involves identifying minor deviations capable of violating the specified requirement. we present an innovative two - layer simulation - based analysis framework designed to identify subtle robustness violations. to assess our methodology, we devise a series of benchmark problems wherein system parameters can be adjusted to emulate various forms of uncertainties and disturbances. initial evaluations indicate that our falsification approach proficiently identifies robustness violations, providing valuable insights for comparing robustness between conventional and reinforcement learning ( rl ) - based controllers
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arxiv:2311.07462
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this paper considers a cross - layer adaptive modulation system that is modeled as a markov decision process ( mdp ). we study how to utilize the monotonicity of the optimal transmission policy to relieve the computational complexity of dynamic programming ( dp ). in this system, a scheduler controls the bit rate of the m - quadrature amplitude modulation ( m - qam ) in order to minimize the long - term losses incurred by the queue overflow in the data link layer and the transmission power consumption in the physical layer. the work is done in two steps. firstly, we observe the l - natural - convexity and submodularity of dp to prove that the optimal policy is always nondecreasing in queue occupancy / state and derive the sufficient condition for it to be nondecreasing in both queue and channel states. we also show that, due to the l - natural - convexity of dp, the variation of the optimal policy in queue state is restricted by a bounded marginal effect : the increment of the optimal policy between adjacent queue states is no greater than one. secondly, we use the monotonicity results to present two low complexity algorithms : monotonic policy iteration ( mpi ) based on l - natural - convexity and discrete simultaneous perturbation stochastic approximation ( dspsa ). we run experiments to show that the time complexity of mpi based on l - natural - convexity is much lower than that of dp and the conventional mpi that is based on submodularity and dspsa is able to adaptively track the optimal policy when the system parameters change.
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arxiv:1508.05383
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we report on a study of the analytical structure of the landau gauge gluon, ghost and quark propagators taken from lattice simulations using large physical volumes, to better access the ir region, and large gauge ensembles to reduce the statistical uncertainties. the investigation uses pad \ ' e approximants to look at poles and branch cuts for each of the propagators. for the gluon propagator we identify complex conjugate poles and a branch point. for the ghost propagator the procedure identifies a pole at zero momentum and a branch point for minkowski - like momenta. the quark propagator appears to have a pole for minkowski - like momenta that is correlated with the pion mass as expected from pcac.
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arxiv:2111.04320
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we report progress in the development of a model - based hybrid probabilistic approach to an on - board ivhm for solid rocket boosters ( srbs ) that can accommodate the abrupt changes of the model parameters in various nonlinear dynamical off - nominal regimes. the work is related to the orion mission program. specifically, a case breach fault for srbs is considered that takes into account burning a hole through the rocket case, as well as ablation of the nozzle throat under the action of hot gas flow. a high - fidelity model ( hfm ) of the fault is developed in fluent in cylindrical symmetry. the results of the fluent simulations are shown to be in good agreement with quasi - stationary approximation and analytical solution of a system of one - dimensional partial differential equations ( pdes ) for the gas flow in the combustion chamber and in the hole through the rocket case.
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arxiv:0807.1519
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we establish the existence of multiple solutions for singular quasilinear elliptic problems with a precise sign information : two opposite constant sign solutions and a nodal solution. the approach combines sub - supersolutions method and leray - schauder topological degree involving perturbation argument.
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arxiv:2310.17960
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as you read these words you are using a complex biological neural network. you have a highly interconnected set of some neurons to facilitate your reading, breathing, motion and thinking. each of your biological neurons, a rich assembly of tissue and chemistry, has the complexity, if not the speed, of a microprocessor. some of your neural structure was with you at birth. other parts have been established by experience.
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arxiv:1811.11534
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recent experimental studies have demonstrated that cellular motion can be directed by topographical gradients, such as those resulting from spatial variations in the features of a micropatterned substrate. this phenomenon, known as topotaxis, is especially prominent among cells persistently crawling within a spatially varying distribution of cell - sized obstacles. in this article we introduce a toy model of topotaxis based on active brownian particles constrained to move in a lattice of obstacles, with space - dependent lattice spacing. using numerical simulations and analytical arguments, we demonstrate that topographical gradients introduce a spatial modulation of the particles ' persistence, leading to directed motion toward regions of higher persistence. our results demonstrate that persistent motion alone is sufficient to drive topotaxis and could serve as a starting point for more detailed studies on self - propelled particles and cells.
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arxiv:1908.06078
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entanglement is a resource in quantum information theory when state manipulation is restricted to local operations assisted by classical communication ( locc ). it is therefore of paramount importance to decide which locc transformations are possible and, particularly, which states are maximally useful under this restriction. while the bipartite maximally entangled state is well known ( it is the only state that cannot be obtained from any other and, at the same time, it can be transformed to any other by locc ), no such state exists in the multipartite case. in order to cope with this fact, we introduce here the notion of the maximally entangled set ( mes ) of n - partite states. this is the set of states which are maximally useful under locc manipulation, i. e. any state outside of this set can be obtained via locc from one of the states within the set and no state in the set can be obtained from any other state via locc. we determine the mes for states of three and four qubits and provide a simple characterization for them. in both cases, infinitely many states are required. however, while the mes is of measure zero for 3 - qubit states, almost all 4 - qubit states are in the mes. this is because, in contrast to the 3 - qubit case, deterministic locc transformations are almost never possible among fully entangled four - partite states. we determine the measure - zero subset of the mes of locc convertible states. this is the only relevant class of states for entanglement manipulation.
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arxiv:1305.7398
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this work studies mode stability of an stu black hole with four pairwise equal $ \ rm { u ( 1 ) } $ charges in four spacetime dimensions. we investigate bosonic perturbations for probe fields of different spins through the transformation technique devised by whiting in 1989. finally, we introduce connection relations inspired by the work of ~ duzta \ c { s } ( 2016 ) to prove the absence of unstable modes that solve the torsion - modified dirac equation appropriate for this black hole background.
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arxiv:2312.04929
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in this paper we give a complementary view of some of the results on group systems by forney and trott. we find an encoder of a group system which has the form of a time convolution. we consider this to be a time domain encoder while the encoder of forney and trott is a spectral domain encoder. we study the outputs of time and spectral domain encoders when the inputs are the same, and also study outputs when the same input is used but time runs forward and backward. in an abelian group system, all four cases give the same output for the same input, but this may not be true for a nonabelian system. moreover, time symmetry and harmonic symmetry are broken for the same reason. we use a canonic form, a set of tensors, to show how the outputs are related. these results show there is a time and harmonic theory of group systems.
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arxiv:1211.2340
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unconventional superconductivity on a honeycomb lattice has received increasing interest since the discovery of graphene primarily due to the similarities between materials with a honeycomb lattice and cuprate superconductors. many theoretical studies have been conducted on superconductivity on a honeycomb lattice, however, a consistent picture is still lacking. in this article we have extended the theory of kinetic - energy - driven superconductivity, which has been developed to investigate unconventional superconductivity in cuprate superconductors, to explore superconductivity on a honeycomb lattice within the $ t $ - $ j $ model. our results demonstrate that the charge - carrier pair gap parameter with $ d _ { x ^ { 2 } - y ^ { 2 } } + { \ rm i } d _ { xy } $ - wave symmetry exhibits a dome - like shape as a function of doping, with superconductivity emerging at a certain doping concentration and disappearing at high doping levels, similar to what has been observed in cuprate and cobaltate superconductors. furthermore, the charge - carrier pair gap parameter decreases with increasing the value of $ j / t $ ( the antiferromagnetic exchange coupling constant relative to the nearest - neighbor hopping integral ), and approaches zero when $ j / t $ reaches a sufficiently large value. this indicates that the antiferromagnetic order will suppress the superconducting state and a sufficiently strong exchange coupling will completely destroy the superconductivity. taking into account our present results together with the corresponding results of cuprate and cobaltate superconductors, it appears that the dome - like shape of the doping dependence of the charge - carrier pair gap parameter may be a common feature in doped mott insulators.
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arxiv:2312.01972
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we study the nonequilibrium phase transition in the two - dimensional contact process on a randomly diluted lattice by means of large - scale monte - carlo simulations for times up to $ 10 ^ { 10 } $ and system sizes up to $ 8000 \ times 8000 $ sites. our data provide strong evidence for the transition being controlled by an exotic infinite - randomness critical point with activated ( exponential ) dynamical scaling. we calculate the critical exponents of the transition and find them to be universal, i. e., independent of disorder strength. the griffiths region between the clean and the dirty critical points exhibits power - law dynamical scaling with continuously varying exponents. we discuss the generality of our findings and relate them to a broader theory of rare region effects at phase transitions with quenched disorder. our results are of importance beyond absorbing state transitions because according to a strong - disorder renormalization group analysis, our transition belongs to the universality class of the two - dimensional random transverse - field ising model.
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arxiv:0810.1569
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we develop a formalism of multicomponent bkp hierarchies using elementary geometry of spinors. the multicomponent kp and the modified kp hierarchy ( hence all their reductions like kdv, nls, akns or ds ) are reductions of the multicomponent bkp.
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arxiv:solv-int/9706006
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we are reaching the point where spectropolarimetric surveys have run for long enough to reveal solar - like magnetic activity cycles. in this paper we investigate what would be the best strategy to identify solar - like magnetic cycles and ask which large - scale magnetic field parameters best follow a solar - type magnetic cycle and are observable with the zeeman - doppler - imaging ( zdi ) technique. we approach these questions using the 3d non - potential flux transport simulations of \ cite { yeates2012 } modelling the solar vector magnetic field over 15 years ( centred on solar cycle 23 ). the flux emergence profile was extracted from solar synoptic maps and used as input for a photospheric flux transport model in combination with a non - potential coronal evolution model. we synthesise spectropolarimetric data from the simulated maps and reconstruct them using zdi. the zdi observed solar cycle is set into the context of other cool star observations and we present observable trends of the magnetic field topology with time, sunspot number and s - index. we find that the axisymmetric energy fraction is the best parameter of the zdi detectable large - scale field to trace solar - like cycles. neither the surface averaged large - scale field or the total magnetic energy is appropriate. zdi seems also to be able to recover the increase of the toroidal energy with s - index. we see further that zdi might unveil hints of the dynamo modes that are operating and of the global properties of the small - scale flux emergence like active latitudes.
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arxiv:2010.10214
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analyses of very accurate corot space photometry, past johnson v photoelectric photometry and high - resolution \ ' echelle spectra led to the determination of improved and consistent fundamental stellar properties of both components of au mon. we derived new, accurate ephemerides for both the orbital motion ( with a period of 11. 113d ) and the long - term, overall brightness variation ( with a period of 416. 9d ) of this strongly interacting be + g semi - detached binary. it is shown that this long - term variation must be due to attenuation of the total light by some variable circumbinary material. we derived the binary mass ratio $ m _ { \ rm g } / m _ { \ rm b } $ = 0. 17 \ p0. 03 based on the assumption that the g - type secondary fills its roche lobe and rotates synchronously. using this value of the mass ratio as well as the radial velocities of the g - star, we obtained a consistent light curve model and improved estimates of the stellar masses, radii, luminosities and effective temperatures. we demonstrate that the observed lines of the b - type primary may not be of photospheric origin. we also discover rapid and periodic light changes visible in the high - quality residual corot light curves. au mon is put into perspective by a comparison with known binaries exhibiting long - term cyclic light changes.
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arxiv:0909.1546
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we study analytically the plasmonic modes in the graphene - coated dielectric nanowire, based on the explicit form of nonlinear surface conductivity of graphene. the propagation constants of different plasmonic modes can be tuned by the input power at the order of a few tenths of mw. the lower and upper mode bifurcation branches are connected at the limitation value of the input power. moreover, due to the nonlinearity of graphene, the dispersion curves of plasmonic modes at different input powers form an energy band, which is in sharp contrast with the single dispersion curve in the limit of zero input power.
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arxiv:1505.02957
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in this paper we show that it is possible to extend the framework of persichetti ' s code - based framework and create a secure kem based on the mceliece protocol. this provides greater flexibility in the application of coding theory as a basis for cryptographic purposes.
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arxiv:1706.06306
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the double pulsar system, psr j0737 $ - $ 3039a / b, consists of two neutron stars bound together in a highly relativistic orbit that is viewed nearly edge - on from the earth. this alignment results in brief radio eclipses of the fast - rotating pulsar a when it passes behind the toroidal magnetosphere of the slow - rotating pulsar b. the morphology of these eclipses is strongly dependent on the geometric orientation and rotation phase of pulsar b, and their time - evolution can be used to constrain the geodetic precession rate of the pulsar. we demonstrate a bayesian inference framework for modelling eclipse light - curves obtained with meerkat between 2019 - 2023. using a hierarchical inference approach, we obtained a precession rate of $ \ omega _ { \ rm so } ^ { \ rm b } = { 5. 16 ^ { \ circ } } ^ { + 0. 32 ^ { \ circ } } _ { - 0. 34 ^ { \ circ } } $ yr $ ^ { - 1 } $ for pulsar b, consistent with predictions from general relativity to a relative uncertainty of 6. 5 %. this updated measurement provides a 6. 1 % test of relativistic spin - orbit coupling in the strong - field regime. we show that a simultaneous fit to all of our observed eclipses can in principle return a $ \ sim $ 1. 5 % test of spin - orbit coupling. however, systematic effects introduced by the current geometric orientation of pulsar b along with inconsistencies between the observed and predicted eclipse light curves result in difficult to quantify uncertainties. assuming the validity of general relativity, we definitively show that the spin - axis of pulsar b is misaligned from the total angular momentum vector by $ 40. 6 ^ { \ circ } \ pm 0. 1 ^ { \ circ } $ and that the orbit of the system is inclined by approximately $ 90. 5 ^ { \ circ } $ from the direction of our line of sight. our measured geometry for pulsar b suggests the largely empty emission cone contains an elongated horseshoe shaped beam centered on the magnetic axis, and that it may not be re - detected as a radio pulsar until early - 2035.
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arxiv:2311.06445
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we study the dynamics of a mechanical oscillator with linear and cubic forces - the duffing oscillator - subject to a feedback mechanism that allows the system to sustain autonomous periodic motion with well - defined amplitude and frequency. first, we characterize the autonomous motion for both hardening and softening nonlinearities. then, we analyze the oscillator ' s synchronizability by an external periodic force. we find a regime where, unexpectedly, the frequency range where synchronized motion is possible becomes wider as the amplitude of oscillations grows. this effect of nonlinearities may find application in technological uses of mechanical duffing oscillators - for instance, in the design of time - keeping devices at the microscale - which we briefly review.
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arxiv:1412.3299
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there are several ways to associate a complex structure to a ribbon graph. in the construction of dessins d ' enfants a single riemann surface is associated to each graph. we call it the grothendieck model of a ribbon graph. the goal of the present paper is to discuss one more such construction, depending on some parameters - that of chekhov - fock. we prove that putting all parametres equal to 0, we obtain the grothendieck model of this graph.
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arxiv:math/0210183
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pediatric central nervous system tumors are the leading cause of cancer - related deaths in children. the five - year survival rate for high - grade glioma in children is less than 20 %. the development of new treatments is dependent upon multi - institutional collaborative clinical trials requiring reproducible and accurate centralized response assessment. we present the results of the brats - peds 2023 challenge, the first brain tumor segmentation ( brats ) challenge focused on pediatric brain tumors. this challenge utilized data acquired from multiple international consortia dedicated to pediatric neuro - oncology and clinical trials. brats - peds 2023 aimed to evaluate volumetric segmentation algorithms for pediatric brain gliomas from magnetic resonance imaging using standardized quantitative performance evaluation metrics employed across the brats 2023 challenges. the top - performing ai approaches for pediatric tumor analysis included ensembles of nnu - net and swin unetr, auto3dseg, or nnu - net with a self - supervised framework. the bratspeds 2023 challenge fostered collaboration between clinicians ( neuro - oncologists, neuroradiologists ) and ai / imaging scientists, promoting faster data sharing and the development of automated volumetric analysis techniques. these advancements could significantly benefit clinical trials and improve the care of children with brain tumors.
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arxiv:2407.08855
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the paper numerically investigates the propagation of galactic cosmic rays in a model magnetic field, which is a composition of an isotropic turbulent field with the kolmogorov turbulence spectrum and a regular constant field. the dependence of the diffusion tensor components on the particle energy is studied. it is shown that the transport anisotropy increases with decreasing energy.
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arxiv:2211.08873
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deductive methods for the verification of hybrid systems vary on the format of statements in correctness proofs. building on the example of hoare triple - based reasoning, we have investigated several such methods for systems described in hybrid csp, each based on a different assertion language, notation for time, and notation for proofs, and each having its pros and cons with respect to expressive power, compositionality and practical convenience. in this paper we propose a new approach based on weakly monotonic time as the semantics for interleaving, the duration calculus ( dc ) with infinite intervals and general fixpoints as the logic language, and a new meaning for hoare - like triples which unifies assertions and temporal conditions. we include a proof system for reasoning about the properties of systems written in the new form of triples that is complete relative to validity in dc.
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arxiv:1706.06246
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this study provides an analysis of atmospheric neutrino oscillations at the essnusb far detector facility. the prospects of the two cylindrical water cherenkov detectors with a total fiducial mass of 540 kt are investigated over 10 years of data taking in the standard three - flavor oscillation scenario. we present the confidence intervals for the determination of mass ordering, $ \ theta _ { 23 } $ octant as well as for the precisions on $ \ sin ^ 2 \ theta _ { 23 } $ and $ | \ delta m _ { 31 } ^ 2 | $. it is shown that mass ordering can be resolved by $ 3 \ sigma $ cl ( $ 5 \ sigma $ cl ) after 4 years ( 10 years ) regardless of the true neutrino mass ordering. correspondingly, the wrong $ \ theta _ { 23 } $ octant could be excluded by $ 3 \ sigma $ cl after 4 years ( 8 years ) in the case where the true neutrino mass ordering is normal ordering ( inverted ordering ). the results presented in this work are complementary to the accelerator neutrino program in the essnusb project.
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arxiv:2407.21663
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accretion around black holes is very often characterized by distinctive x - ray reflection features ( mostly, iron inner - shell transitions ), which arise due to the primary radiation being reprocessed by a dense and relatively colder medium, such as an accretion disk. most reflection modeling assume that emission stops at the inner - most stable circular orbit ( isco ), and that for smaller radii - in the plunging region - the density drops and the accretion flow is far too ionized for efficient line production. we investigate the spectral features of the reflection in the plunging regions of optically - thick and geometrically - thin accretion disks around black holes. we show that for cases in which the density profile is considered constant ( as expected in highly magnetized flows ), or in cases in which the disk density is high enough such that the ionization still allows line formation within the isco, there is a significant modification of the observed reflected spectrum. consistent with previous studies, we found that the impact of the radiation reprocessed in the plunging region is stronger the lower the black hole spin, when the plunging region subtends a larger area. likewise, as for the case of standard reflection modeling, the relativistic broadening of the iron line is more pronounced at low inclination, whereas the blueshift and relativistic beaming effect is dominant at high inclination. we also tested the effects of various prescriptions of the stress at the isco radius on the reflection spectrum, and found that several of these cases appear to show line profiles distinct enough to be distinguishable with reasonably good quality observational data.
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arxiv:2312.09210
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predicting ambulance demand accurately in fine resolutions in space and time is critical for ambulance fleet management and dynamic deployment. typical challenges include data sparsity at high resolutions and the need to respect complex urban spatial domains. to provide spatial density predictions for ambulance demand in melbourne, australia as it varies over hourly intervals, we propose a predictive spatio - temporal kernel warping method. to predict for each hour, we build a kernel density estimator on a sparse set of the most similar data from relevant past time periods ( labeled data ), but warp these kernels to a larger set of past data irregardless of time periods ( point cloud ). the point cloud represents the spatial structure and geographical characteristics of melbourne, including complex boundaries, road networks, and neighborhoods. borrowing from manifold learning, kernel warping is performed through a graph laplacian of the point cloud and can be interpreted as a regularization towards, and a prior imposed, for spatial features. kernel bandwidth and degree of warping are efficiently estimated via cross - validation, and can be made time - and / or location - specific. our proposed model gives significantly more accurate predictions compared to a current industry practice, an unwarped kernel density estimation, and a time - varying gaussian mixture model.
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arxiv:1507.00363
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data selection is critical for enhancing the performance of language models, particularly when aligning training datasets with a desired target distribution. this study explores the effects of different data selection methods and feature types on model performance. we evaluate whether selecting data subsets can influence downstream tasks, whether n - gram features improve alignment with target distributions, and whether embedding - based neural features provide complementary benefits. through comparative experiments using baseline random selection methods and distribution aligned approaches, we provide insights into the interplay between data selection strategies and model training efficacy. all code for this study can be found on \ href { https : / / github. com / jgu13 / hir - hybrid - importance - resampling - for - language - models } { github repository }.
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arxiv:2501.03826
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recent advancements in assured autonomy have brought autonomous vehicles ( avs ) closer to fruition. despite strong evidence that multi - sensor, multi - agent ( msma ) systems can yield substantial improvements in the safety and security of avs, there exists no unified framework for developing and testing representative msma configurations. using the recently - released autonomy platform, avstack, this work proposes a new framework for datasets, models, and algorithms in msma autonomy. instead of releasing a single dataset, we deploy a dataset generation pipeline capable of generating unlimited volumes of ground - truth - labeled msma perception data. the data derive from cameras ( semantic segmentation, rgb, depth ), lidar, and radar, and are sourced from ground - vehicles and, for the first time, infrastructure platforms. pipelining generating labeled msma data along with avstack ' s third - party integrations defines a model training framework that allows training multi - sensor perception for vehicle and infrastructure applications. we provide the framework and pretrained models open - source. finally, the dataset and model training pipelines culminate in insightful multi - agent case studies. while previous works used specific ego - centric multi - agent designs, our framework considers the collaborative autonomy space as a network of noisy, time - correlated sensors. within this environment, we quantify the impact of the network topology and data fusion pipeline on an agent ' s situational awareness.
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arxiv:2312.04970
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= 0 \ neq \ ell $.
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arxiv:2303.04112
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data quality is an important consideration in many engineering applications and projects. data collection procedures do not always involve careful utilization of the most precise instruments and strictest protocols. as a consequence, data are invariably affected by imprecision and sometimes sharply varying levels of quality of the data. different mathematical representations of imprecision have been suggested, including a classical approach to censored data which is considered optimal when the proposed error model is correct, and a weaker approach called interval statistics based on partial identification that makes fewer assumptions. maximizing the quality of statistical results is often crucial to the success of many engineering projects, and a natural question that arises is whether data of differing qualities should be pooled together or we should include only precise measurements and disregard imprecise data. some worry that combining precise and imprecise measurements can depreciate the overall quality of the pooled data. some fear that excluding data of lesser precision can increase their overall uncertainty about results because lower sample size implies more sampling uncertainty. this paper explores these concerns and describes simulation results that show when it is advisable to combine fairly precise data with rather imprecise data by comparing analyses using different mathematical representations of imprecision. pooling data sets is preferred when the low - quality data set does not exceed a certain level of uncertainty. however, so long as the data are random, it may be legitimate to reject the low - quality data if its reduction of sampling uncertainty does not counterbalance the effect of its imprecision on the overall uncertainty.
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arxiv:2210.13863
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the phase variation of the superconducting gap over the ( normal ) fermi surface of the high - temperature superconductors remains a significant unresolved question. is the phase of the gap constant, does it change sign, or is it perhaps complex? a detailed answer to this question would provide important constraints on various pairing mechanisms. here we propose a new method for measuring the relative gap phase on the fermi surface which is direct, is angle - resolved, and probes the bulk. the required experiments involve measuring phonon linewidths in the normal and superconducting state, with resolution available in current facilities. we primarily address the la _ 1. 85sr _. 15cuo _ 4 material, but also propose a more detailed study of a specific phonon in bi _ 2sr _ 2cacu _ 2o _ 8.
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arxiv:cond-mat/9303027
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we demonstrate that in a ferromagnetic substrate, which is continuously driven out of equilibrium by a field moving with constant velocity $ v $, at least two types of friction may occur when $ v $ goes to zero : the substrate may feel a friction force proportional to $ v $ ( stokes friction ), if the field changes on a time scale which is longer than the intrinsic relaxation time. on the other hand, the friction force may become independent of $ v $ in the opposite case ( coulomb friction ). these observations are analogous to e. g. solid friction. the effect is demonstrated in both, the ising ( one spin dimension ) and the heisenberg model ( three spin dimensions ), irrespective which kind of dynamics ( metropolis spin - flip dynamics or landau - lifshitz - gilbert precessional dynamics ) is used. for both models the limiting case of coulomb friction can be treated analytically. furthermore we present an empiric expression reflecting the correct stokes behavior and therefore yielding the correct cross - over velocity and dissipation.
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arxiv:1111.2494
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the rapid advancement of large language models ( llms ) has opened new boundaries in the extraction and synthesis of medical knowledge, particularly within evidence synthesis. this paper reviews the state - of - the - art applications of llms in the biomedical domain, exploring their effectiveness in automating complex tasks such as evidence synthesis and data extraction from a biomedical corpus of documents. while llms demonstrate remarkable potential, significant challenges remain, including issues related to hallucinations, contextual understanding, and the ability to generalize across diverse medical tasks. we highlight critical gaps in the current research literature, particularly the need for unified benchmarks to standardize evaluations and ensure reliability in real - world applications. in addition, we propose directions for future research, emphasizing the integration of state - of - the - art techniques such as retrieval - augmented generation ( rag ) to enhance llm performance in evidence synthesis. by addressing these challenges and utilizing the strengths of llms, we aim to improve access to medical literature and facilitate meaningful discoveries in healthcare.
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arxiv:2412.03531
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we evaluate the torque acting on a gravitational perturber on a retrograde circular orbit in the midplane of a gaseous disk. we assume that the mass of this satellite is so low it weakly disturbs the disk ( type i migration ). the perturber may represent the companion of a binary system with a small mass ratio. we compare the results of hydrodynamical simulations with analytic predictions. our two - dimensional ( 2d ) simulations indicate that the torque acting on a perturber with softening radius $ r _ { \ rm soft } $ can be accounted for by a scattering approach if $ r _ { \ rm soft } < 0. 3h $, where $ h $ is defined as the ratio between the sound speed and the angular velocity at the orbital radius of the perturber. for $ r _ { \ rm soft } > 0. 3h $, the torque may present large and persistent oscillations, but the resultant time - averaged torque decreases rapidly with increasing $ r _ { \ rm soft } / h $, in agreement with previous analytical studies. we then focus on the torque acting on small - size perturbers embedded in full three - dimensional ( 3d ) disks and argue that the density waves propagating at distances $ \ lesssim h $ from the perturber contribute significantly to the torque because they transport angular momentum. we find a good agreement between the torque found in 3d simulations and analytical estimates based on ballistic orbits. we compare the radial migration timescales of prograde versus retrograde perturbers. for a certain range of the perturber ' s mass and aspect ratio of the disk, the radial migration timescale in the retrograde case may be appreciably shorter than in the prograde case. we also provide the smoothing length required in 2d simulations in order to account for 3d effects.
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arxiv:1805.08852
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we study brown ' s definition of the probabilistic zeta function of a finite lattice as a generalization of that of a finite group. we propose a natural alternative or extension that may be better suited for non - atomistic lattices. the probabilistic zeta function admits a general dirichlet series expression, which unlike for groups, need not be ordinary. we compute the function for several examples of finite lattices, establishing a connection with the stirling numbers of the second kind in the case of the divisibility lattice. furthermore, in the context of moving from groups to lattices, we are interested in lattices with probabilistic zeta function given by ordinary dirichlet series. in this regard, we focus on partition lattices and $ d $ - divisible partition lattices. using the prime number theorem, we show that the probabilistic zeta functions of the latter typically fail to be ordinary dirichlet series.
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arxiv:2112.13766
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we consider power control in cognitive radio networks where secondary users identify and exploit instantaneous and local spectrum opportunities without causing unacceptable interference to primary users. we qualitatively characterize the impact of the transmission power of secondary users on the occurrence of spectrum opportunities and the reliability of opportunity detection. based on a poisson model of the primary network, we quantify these impacts by showing that ( i ) the probability of spectrum opportunity decreases exponentially with respect to the transmission power of secondary users, where the exponential decay constant is given by the traffic load of primary users ; ( ii ) reliable opportunity detection is achieved in the two extreme regimes in terms of the ratio between the transmission power of secondary users and that of primary users. such analytical characterizations allow us to study power control for optimal transport throughput under constraints on the interference to primary users. furthermore, we reveal the difference between detecting primary signals and detecting spectrum opportunities, and demonstrate the complex relationship between physical layer spectrum sensing and mac layer throughput. the dependency of this phy - mac interaction on the application type and the use of handshake signaling such as rts / cts is illustrated.
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arxiv:0809.0533
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we investigate the scaling behavior of the cluster size distribution in the drossel - schwabl forest fire model ( ds - ffm ) by means of large scale numerical simulations, partly on ( massively ) parallel machines. it turns out that simple scaling is clearly violated, as already pointed out by grassberger [ p. grassberger, j. phys. a : math. gen. 26, 2081 ( 1993 ) ], but largely ignored in the literature. most surprisingly the statistics not seems to be described by a universal scaling function, and the scale of the physically relevant region seems to be a constant. our results strongly suggest that the ds - ffm is not critical in the sense of being free of characteristic scales.
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arxiv:cond-mat/0201306
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this report summarizes the results of the work done in collaboration with k. rajagopal and e. shuryak. we analyze the physics behind the event - by - event fluctuations in heavy ion collisions. using thermodynamic description of the ensemble of events we analyze and quantify various effects that are sensitive to the proximity of the critical point on the phase diagram of qcd.
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arxiv:hep-ph/9906242
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a lagrangian of electroweak interactions without higgs is used to study the contributions of quarks and leptons to the masses of the w and the z bosons. it is shown that the $ su ( 2 ) \ times u ( 1 ) $ symmetry is broken by both fermion masses and axial - vector components of the intermediate bosons. the masses of the w and the z bosons are obtained to be ( m ^ { 2 } _ { w } = { 1 \ over2 } g ^ { 2 } m ^ { 2 } _ { t } ) and ( m ^ { 2 } _ { z } = \ rho m ^ { 2 } _ { w } / cos ^ { 2 } \ theta _ { w } ) with ( \ rho \ simeq 1 ). two fixed gauge fixing terms for w and z boson fields are derived respectively. a coupling between photon and z boson is predicted. massive neutrinos are required.
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arxiv:hep-ph/9709332
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the influence of magnitoelastic ( me ) interaction on the stabilization of long - range magnetic order ( lmo ) in the two - dimensional easy - plane ferromagnetic is investigated in this work. the account of me exchange results in the root dispersion law of magnons and appearance of me gap in the spectra of elementary excitations. such a behavior of the spectra testifies to the stabilization of lmo and finite curie ' s temperature.
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arxiv:cond-mat/9807129
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to a univariate monic polynomial is attached a special planar forest that is called the picture of the polynomial. isotopy classes of pictures are called signatures. all combinatorially possible signatures are realized and spaces of polynomials realizing a given signature are contractible. a finite cell complex for the cohomology of the braid groups is obtained.
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arxiv:1702.05885
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the grand canonical thermodynamics of a bosonic system is studied in order to identify the footprint of its own high - density quantum phase transition. the phases displayed by the system at zero temperature establish recognizable patterns at finite temperature that emerged in the proximity of the boundary of the equilibrium diagram. the gaped phase induces a state of collectivism / condensation at finite temperature in which population cumulates into the ground state in spite of interacting attractively. the work sets the foundation to approach the effect of attraction in the formation of a molecular condensate.
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arxiv:2106.13298
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price perception by consumers represents a challenge to the ability of a business to correctly and profitably price and sell their products or services in a given market and any new target market. complicating the perception of prices is the dynamics of price and income elasticity, both of which are key for estimating demand. this article proposes a novel and elegant identity that conceptualizes elasticity as a means of quantifying the potential for price perception problems in a market. elasticity studies from 1990 to 2023 ( n = 30 ) were sampled to evaluate the relationship between price and income elasticity for various consumer commodities using the identity. the results suggest that, given known price and income elasticity values, a business can anticipate pricing perception problems in advance and address the potential for damaging distortion of their value proposition. further, the business can use this insight to correctly choose a strategic pricing approach.
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arxiv:2402.05152
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we study $ \ mathbb { z } _ 2 $ - graded identities of simple lie superalgebras over a field of characteristic zero. we prove the existence of the graded pi - exponent for such algebras.
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arxiv:1603.06192
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a recently proposed model of non - autocatalytic reactions in dipeptide reactions leading to spontaneous symmetry breaking and homochirality is examined. the model is governed by activation, polymerization, epimerization and depolymerization of amino acids. symmetry breaking is primarily a consequence of the fact that the rates of reactions involving homodimers and heterodimers are different, i. e., stereoselective, and on the fact that epimerization can only occur on the n - terminal residue and not on the cterminal residue. this corresponds to an auto - inductive cyclic process that works only in one sense. it is argued that epimerization mimics both autocatalytic behavior as well as mutual antagonism - both of which were known to be crucial for producing full homochirality.
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arxiv:q-bio/0610051
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the quasi two - dimensional magnetic bani $ _ { 2 } $ v $ _ { 2 } $ o $ _ { 8 } $ is studied by using high - resolution thermal expansion in magnetic fields up to 10 t applied along the c - axis. a slight increase of about 1 % of the three - dimensional antiferromagnetic ordering temperature $ t _ n $ is observed at 10 t. positive and negative pressure dependencies of $ t _ n $, respectively, are inferred from the thermal expansion $ \ alpha ( t ) $ for pressures applied along the $ a $ - and $ c $ - axes.
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arxiv:cond-mat/0606174
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for autonomous vehicles, high - precision real - time localization is the guarantee of stable driving. compared with the visual odometry ( vo ), the lidar odometry ( lo ) has the advantages of higher accuracy and better stability. however, 2d lo is only suitable for the indoor environment, and 3d lo has less efficiency in general. both are not suitable for the online localization of an autonomous vehicle in an outdoor driving environment. in this paper, a direct lo method based on the 2. 5d grid map is proposed. the fast semi - dense direct method proposed for vo is employed to register two 2. 5d maps. experiments show that this method is superior to both the 3d - ndt and loam in the outdoor environment.
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arxiv:1809.10199
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we use high resolution n - body / gasdynamical simulations to investigate the effects of a photoionizing uv background on the assembly of disk galaxies in hierarchically clustering universes. we focus on the mass and rotational properties of gas that can cool to form centrifugally supported disks in dark matter halos of different mass. photoheating can significantly reduce the amount of gas that can cool in galactic halos. depending on the strength of the uv background field, the amount of cooled gas can be reduced by up to $ 50 \ % $ in systems with circular speeds in the range $ 80 $ - $ 200 $ \ kms. the magnitude of the effect, however, is not enough to solve the ` ` overcooling ' ' problem that plagues hierarchical models of galaxy formation if the uv background is chosen to be consistent with estimates based on recent observations of qso absorption systems. photoionization has little effect on the collapse of gas at high redshift and affects preferentially gas that is accreted at late times. since disks form inside - out, accreting higher angular momentum gas at later times, disks formed in the presence of a uv background have spins that are even smaller than those formed in simulations that do not include the effects of photoionization. this exacerbates the angular momentum problem that afflicts hierarchical models of disk formation. we conclude that photoionization cannot provide the heating mechanism required to reconcile hierarchically clustering models with observations. energy feedback and enrichment processes from the formation and evolution of stars must therefore be indispensable ingredients for any successful model of the formation of disk galaxies.
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arxiv:astro-ph/9605043
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the response in data flows transmission in real time is analyzed, for access network scenarios, in which said flows converge on an outgoing link, competing to achieve a certain level of quality of service. the concurrence of these types of flows can generate bursts of packets, which in certain circumstances can compromise the capacity of the buffers to absorb packets in congestion periods. in addition, an analysis of the characteristics of buffers in access devices is presented, especially their size and packet loss. in particular, it describes how these characteristics can affect the quality of multimedia applications when bursty traffic is generated, it also presents possible effects on the traffic of other applications that share a common link.
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arxiv:2111.08105
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significance : cerebral blood flow ( cbf ) imaging is crucial for diagnosing cerebrovascular diseases. however, existing large neuroimaging techniques with high cost, low sampling rate, and poor mobility make them unsuitable for continuous and longitudinal cbf monitoring at the bedside. aim : this study aimed to develop a low - cost, portable, programmable scanning diffuse speckle contrast imaging ( ps - dsci ) technology for fast, high - density, and depth - sensitive imaging of cbf in rodents. approach : the ps - dsci employed a programmable digital micromirror device ( dmd ) for remote line - shape laser ( 785 nm ) scanning on tissue surface and synchronized a 2d camera for capturing boundary diffuse laser speckle contrasts. new algorithms were developed to address deformations of line - shape scanning, thus minimizing cbf reconstruction artifacts. the ps - dsci was examined in head - simulating phantoms and adult mice. results : the ps - dsci enables resolving intralipid particle flow contrasts at different tissue depths. in vivo experiments in adult mice demonstrated the capability of ps - dsci to image global / regional cbf variations induced by 8 % co2 inhalation and transient carotid artery ligations. conclusions : compared to conventional point scanning, the line scanning in ps - dsci significantly increases spatiotemporal resolution. the high sampling rate of ps - dsci is crucial for capturing rapid cbf changes while high spatial resolution is important for visualizing brain vasculature.
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arxiv:2408.12715
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two very similar proposals have been made recently for witnessing nonclassical features of gravity, by bose et al. and by marletto and vedral. however, while these proposals are asserted to be very general, they are in fact based on a very strong claim : that quantum systems cannot become entangled via a classical intermediary. we point out that the support provided for this claim is only applicable to a very limited class of quantum - classical interaction models, corresponding to koopman - type dynamics. we show that the claim is also valid for mean - field models, but that it is contradicted by explicit counterexamples based on the configuration - ensemble model. thus, neither proposal provides a definitive test of nonclassical gravity.
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arxiv:1707.07974
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we study the diluted ising ferromagnet on the bethe lattice as a case study for the application of the cavity method to problems with griffiths - mccoy singularities. specifically, we are able to make much progress at infinite coupling where we compute, from the cavity method, the density of lee - yang zeroes in the paramagnetic griffiths region as well as the properties of the phase transition to the ferromagnet. this phase transition is itself of a griffiths - mccoy character albeit with a power law distribution of cluster sizes.
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arxiv:0712.3540
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we study the role of impurities in a two - band superconductor, and elucidate the nature of the recently predicted transition from s _ { + - } state to s _ { + + } state induced by interband impurity scattering. using a ginzburg - landau theory, derived from microscopic equations, we demonstrate that close to t _ c this transition is necessarily a direct one, but deeper in the superconducting state an intermediate complex state appears. this state has a distinct order parameter, which breaks the time - reversal symmetry, and is separated from the s _ { + - } and s _ { + + } states by phase transitions. based on our results, we suggest a phase diagram for systems with weak repulsive interband pairing, and discuss its relevance to iron - based superconductors.
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arxiv:1306.4268
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password management has long been a persistently challenging task. this led to the introduction of password management software, which has been around for at least 25 years in various forms, including desktop and browser - based applications. this work assesses the ability of two dozen password managers, 12 desktop applications, and 12 browser - plugins, to effectively protect the confidentiality of secret credentials in six representative scenarios. our analysis focuses on the period during which a password manager ( pm ) resides in the ram. despite the sensitive nature of these applications, our results show that across all scenarios, only three desktop pm applications and two browser plugins do not store plaintext passwords in the system memory. oddly enough, at the time of writing, only two vendors recognized the exploit as a vulnerability, reserving cve - 2023 - 23349, while the rest chose to disregard or underrate the issue.
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arxiv:2404.00423
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this paper investigates the poisson geometry associated to a cluster algebra over the complex numbers, and its relationship to compatible torus actions. we show, under some assumptions, that each noetherian cluster algebra has only finitely many torus invariant poisson prime ideals and we show how to obtain using the exchange matrix of an initial seed. in fact, these ideals are independent of the choice of compatible poisson structure. in many interesting cases the ideals can be described more explicitly.
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arxiv:1009.2936
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the question is discussed of what is the speed of gravity ( at the fundamental non - perturbative level ). the question is important, if nowhere else, in discussing the problem of information " lost " in black holes. it turns out that the duly defined " gravitational signal " generally may be causal, superluminal and " semi - superluminal ". in the class of globally hyperbolic spacetimes the two last varieties coincide. and if some ( often imposed, but not always satisfied ) conditions hold, the signals may be \ emph { only } causal. in this sense the speed of gravity does not exceed the speed of light.
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arxiv:1009.1761
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in this paper, we present a theoretical description to the quantum coherence and decoherence phenomena of energy transfer in photosynthesis observed in a recent experiment [ see science 316, 1462 ( 2007 ) ]. as a successive two - color laser pulses with selected frequencies cast on a sample of the photosynthetic purple bacterium rb. sphaeroides two resonant excitations of electrons in chromophores can be generated. however, this effective two - level subsystem will interact with its protein environment and decoherence is inevitable. we describe this subsystem coupled with its environment as a dynamical spin - boson model. the non - markovian decoherence dynamics is described using a quasi - adiabatic propagator path integral ( quapi ) approach. with the photon - induced effective time - dependent level splitting energy and level flip coupling coefficient between the two excited states and the environment - induced non - markovian decoherence dynamics, our theoretical result is in good agreement with the experimental data.
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arxiv:0809.0039
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in this short paper we reply to the comment [ arxiv : 1108. 4543 ] by m. j. t. f. cabbolet on villata ' s theory of antigravity [ arxiv : 1103. 4937 ]. the criticisms of methodological and ontological kind presented by that author come from a misinterpretation of some concepts, perhaps due to some lack of clarity or omission of details in villata ' s original article. in order to clarify these points, here we provide additional explanations regarding the assumptions and results of the theory.
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arxiv:1109.1201
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local search algorithms are well - known methods for solving large, hard instances of the satisfiability problem ( sat ). the performance of these algorithms crucially depends on heuristics for setting noise parameters and scoring variables. the optimal setting for these heuristics varies for different instance distributions. in this paper, we present an approach for learning effective variable scoring functions and noise parameters by using reinforcement learning. we consider satisfiability problems from different instance distributions and learn specialized heuristics for each of them. our experimental results show improvements with respect to both a walksat baseline and another local search learned heuristic.
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arxiv:2307.04608
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in this work we study wave packet dynamics and $ zitterbewegung $, an oscillatory quantum motion, of heavy holes in iii - v semiconductor quantum wells in presence of a quantizing magnetic field. it is revealed that a gaussian wave - packet describing a heavy hole diffuses asymmetrically along the circular orbit while performing cyclotron motion. the wave packet splits into two peaks with unequal amplitudes after a certain time depending on spin - orbit coupling constant. this unequal splitting of the wave packet is attributed to the cubic rashba interaction for heavy holes. the difference in the peak amplitudes disappears with time. at a certain time the two peaks diffuse almost along the entire cyclotron orbit. then tail and head of the diffused wave packet interfere and as a result a completely randomized pattern of the wave packet is observed. the diffusion rate of the wave packet increases with increase of the spin - orbit interaction strength. also strong spin - orbit coupling expedite the splitting and the randomization of the wave packet. we also study the $ zitterbewegung $ in various physical observables such as position, charge current and spin angular momentum of the heavy hole. the $ zitterbewegung $ oscillations are very much sensitive to the initial wave vector of the gaussian wave packet and the strength of the rashba spin - orbit coupling.
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arxiv:1310.7749
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by combining variational monte carlo ( vmc ) and complete - basis - set limit hartree - fock ( hf ) calculations, we have obtained near - exact correlation energies for low - density same - spin electrons on a three - dimensional sphere ( 3 - sphere ), i. e. ~ the surface of a four - dimensional ball. in the vmc calculations, we compare the efficacies of two types of one - electron basis functions for these strongly correlated systems, and analyze the energy convergence with respect to the quality of the jastrow factor. the hf calculations employ spherical gaussian functions ( sgfs ) which are the curved - space analogs of cartesian gaussian functions. at low densities, the electrons become relatively localized into wigner crystals, and the natural sgf centers are found by solving the thomson problem ( i. e. the minimum - energy arrangement of $ n $ point charges ) on the 3 - sphere for various values of $ n $. we have found 11 special values of $ n $ whose thomson sites are equivalent. three of these are the vertices of four - dimensional platonic solids - - - the hyper - tetrahedron ( $ n = 5 $ ), the hyper - octahedron ( $ n = 8 $ ) and the 24 - cell ( $ n = 24 $ ) - - - and a fourth is a highly symmetric structure ( $ n = 13 $ ) which has not previously been reported. by calculating the harmonic frequencies of the electrons around their equilibrium positions, we also find the first - order vibrational corrections to the thomson energy.
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arxiv:1508.02491
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identifying dynamical systems from experimental data is a notably difficult task. prior knowledge generally helps, but the extent of this knowledge varies with the application, and customized models are often needed. neural ordinary differential equations can be written as a flexible framework for system identification and can incorporate a broad spectrum of physical insight, giving physical interpretability to the resulting latent space. in the case of partial observations, however, the data points cannot directly be mapped to the latent state of the ode. hence, we propose to design recognition models, in particular inspired by nonlinear observer theory, to link the partial observations to the latent state. we demonstrate the performance of the proposed approach on numerical simulations and on an experimental dataset from a robotic exoskeleton.
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arxiv:2205.12550
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the histological assessment of human tissue has emerged as the key challenge for detection and treatment of cancer. a plethora of different data sources ranging from tissue microarray data to gene expression, proteomics or metabolomics data provide a detailed overview of the health status of a patient. medical doctors need to assess these information sources and they rely on data driven automatic analysis tools. methods for classification, grouping and segmentation of heterogeneous data sources as well as regression of noisy dependencies and estimation of survival probabilities enter the processing workflow of a pathology diagnosis system at various stages. this paper reports on state - of - the - art of the design and effectiveness of computational pathology workflows and it discusses future research directions in this emergent field of medical informatics and diagnostic machine learning.
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arxiv:1601.00027
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we introduce a disorder - free model of $ s = 1 / 2 $ spins on the square lattice in a constrained hilbert space where two up - spins are not allowed simultaneously on any two neighboring sites of the lattice. the interactions are given by ring - exchange terms on elementary plaquettes that conserve both the total magnetization as well as dipole moment. we show that this model provides a tractable example of strong hilbert space fragmentation in two dimensions with typical initial states evading thermalization with respect to the full hilbert space. given any product state, the system can be decomposed into disjoint spatial regions made of edge and / or vertex sharing plaquettes that we dub as ` ` quantum drums ' '. these quantum drums come in many shapes and sizes and specifying the plaquettes that belong to a drum fixes its spectrum. the spectra of some small drums is calculated analytically. we study two bigger quasi - one - dimensional drums numerically, dubbed ` ` wire ' ' and a ` ` junction of two wires ' ' respectively. we find that these possess a chaotic spectrum but also support distinct families of quantum many - body scars that cause periodic revivals from different initial states. the wire is shown to be equivalent to the one - dimensional pxp chain with open boundaries, a paradigmatic model for quantum many - body scarring ; while the junction of two wires represents a distinct constrained model.
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arxiv:2208.13800
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starting from the observation that kilohertz quasi period oscillations ( khz qpo ) occur in a very narrow range of x - ray luminosities in neutron star low mass x - ray binaries, we try to link the khz qpo observability to variations of the neutron star magnetospheric radius, in response to changing mass inflow rate. at low luminosities, the drop off of khz qpos activity may be explained by the onset of the centrifugal barrier, when the magnetospheric radius reaches the corotation radius. at the opposite side, at higher luminosities, the magnetospheric radius may reach the neutron star and the vanishing of the magnetosphere may led to the stopping of the khz qpos activity. if we apply these constraints, the magnetic fields of atoll ( b ~ 0. 3 - 1 10 ^ 8 g for aql x - 1 ) and z ( b ~ 1 - 8 10 ^ 8 g for cyg x - 2 ) sources can be derived. these limits naturally apply in the framework of beat frequency models but can also work in the case of general relativistic models.
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arxiv:astro-ph/0003210
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we have investigated the magnetic - field induced phases of a typical three - dimensional frustrated magnet, cdcr $ _ 2 $ o $ _ 4 $, in magnetic fields of up to 120 t that is generated by the single - turn coil techniques. we focused on magnetic phase transitions in proximity of a saturated magnetization moment. we utilized both the electromagnetic induction method using magnetic pick - up coils and magneto - optical spectroscopies of the $ d $ - $ d $ transitions and the exciton - magnon - phonon transitions to study the magnetic properties subjected to ultra - high magnetic fields. anomalies were observed in magneto - optical absorption intensity as well as differential magnetization prior to a fully polarized magnetic phase ( a vacuum state in the magnon picture ), revealing a novel magnetic phase associated with changes in both crystal and magnetic structures accompanied by the first order phase transition. magnetic superfluid state such as an umbrella - like magnetic structure or a spin nematic state, is proposed as a candidate for the novel magnetic phase, which is found universal in the series of chromium spinel oxides, $ a $ cr $ _ 2 $ o $ _ 4 $ ( $ a $ = zn, cd, hg ).
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arxiv:1302.3664
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let $ p _ k $ be the subgroup generated by $ k $ th powers of primitive elements in $ f _ r $, the free group of rank $ r $. we show that $ f _ 2 / p _ k $ is finite if and only if $ k $ is $ 1 $, $ 2 $, or $ 3 $. we also fully characterize $ f _ 2 / p _ k $ for $ k = 2, 3, 4 $. in particular, we give a faithful nine dimensional representation of $ f _ 2 / p _ 4 $ with infinite image.
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arxiv:1708.02093
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we compute the cohomology ring of a generalised type of configuration space of points in $ \ mathbb { r } ^ r $. this configuration space is indexed by a graph. in the case the graph is complete the result is known and it is due to arnold and cohen. however, our computations give a generalisation to any graph and an alternative proof of the classical result. moreover, we show that there are deletion - contraction short exact sequences for this cohomology rings.
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arxiv:2004.08370
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marginally stable circular orbits ( mscos ) of a massive test particle are investigated in the spacetime geometry of schwarzschild black hole surrounded by quintessence. for that matter we consider three important scenarios where the equation of state parameter $ \ omega _ { q } $, has one of the following forms ( i ) $ \ omega _ q = - 1 $ ( ii ) $ \ omega _ q = - 2 / 3 $ and ( iii ) $ \ omega _ q = - 1 / 3 $. the existence of such marginally stable circular orbits in these scenarios depend on the range of normalization factor $ \ alpha $. briefly, we show that in the first case such orbits exist only if $ 0 < \ alpha < 4 / 16875 $. moreover in the second case which is a special kiselev black hole it is found that mscos exist when the value of the normalization factor satisfy $ 0 < \ alpha \ leq 0. 00536165238 $. in the last case the mscos are also shown to exist.
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arxiv:1601.01295
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we investigate the heat flow between different terminals in an interacting coherent conductor when inelastic scattering is present. we illustrate our theory with a two - terminal quantum dot setup. two types of heat asymmetries are investigated : electric asymmetry $ \ delta _ e $, which describes deviations of the heat current in a given contact when voltages are exchanged, and contact asymmetry $ \ delta _ c $, which quantifies the difference between the power measured in two distinct electrodes. in the linear regime, both asymmetries agree and are proportional to the seebeck coefficient, the latter following at low temperature a mott - type formula with a dot transmission renormalized by inelasticity. interestingly, in the nonlinear regime of transport we find $ \ delta _ e \ neq \ delta _ c $ and this asymmetry departure depends on the applied bias configuration. our results may be important for the recent experiments by lee et al. [ nature ( london ) 498, 209 ( 2013 ) ], where these asymmetries were measured.
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arxiv:1502.01158
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we utilize the idea underlying the construct of the classical weighted backward shift rolewicz ' s operators to furnish a straightforward approach to a general construct of chaotic unbounded linear operators in a ( real or complex ) banach space with a schauder basis.
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arxiv:1812.02294
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star clusters are studied widely both as benchmarks for stellar evolution models and in their own right. cluster age and mass distributions within galaxies are probes of star formation histories, and of cluster formation and disruption processes. the vast majority of clusters in the universe is small, and it is well known that the integrated fluxes and colors have broad probability distributions, due to small numbers of bright stars. this paper goes beyond the description of predicted probability distributions, and presents results of the analysis of cluster energy distributions in an explicitly stochastic context. the method developed is bayesian. it provides posterior probability distributions in the age - mass - extinction space, using multi - wavelength photometric observations and a large collection of monte - carlo simulations of clusters of finite stellar masses. both ubvi and ubvik datasets are considered, and the study conducted in this paper is restricted to the solar metallicity. we first reassess and explain errors arising from the use of standard analysis methods, which are based on continuous population synthesis models : systematic errors on ages and random errors on masses are large, while systematic errors on masses tend to be smaller. the age - mass distributions obtained after analysis of a synthetic sample are very similar to those found for real galaxies in the literature. the bayesian approach on the other hand, is very successful in recovering the input ages and masses. taking stochastic effects into account is important, more important for instance than the choice of adding or removing near - ir data in many cases. we found no immediately obvious reason to reject priors inspired by previous ( standard ) analyses of cluster populations in galaxies, i. e. cluster distributions that scale with mass as m ^ - 2 and are uniform on a logarithmic age scale.
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arxiv:1003.2334
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highlight detection in sports videos has a broad viewership and huge commercial potential. it is thus imperative to detect highlight scenes more suitably for human interest with high temporal accuracy. since people instinctively suppress blinks during attention - grabbing events and synchronously generate blinks at attention break points in videos, the instantaneous blink rate can be utilized as a highly accurate temporal indicator of human interest. therefore, in this study, we propose a novel, automatic highlight detection method based on the blink rate. the method trains a one - dimensional convolution network ( 1d - cnn ) to assess blink rates at each video frame from the spatio - temporal pose features of figure skating videos. experiments show that the method successfully estimates the blink rate in 94 % of the video clips and predicts the temporal change in the blink rate around a jump event with high accuracy. moreover, the method detects not only the representative athletic action, but also the distinctive artistic expression of figure skating performance as key frames. this suggests that the blink - rate - based supervised learning approach enables high - accuracy highlight detection that more closely matches human sensibility.
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arxiv:2007.01089
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the aim of this paper is to classify bi - hermitian compact surfaces $ ( m, g ) $ whose ricci tensor $ \ rho $ satisfies the relation $ \ nabla _ x \ rho ( x, x ) = \ frac13x \ tau g ( x, x ) $.
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arxiv:0801.1923
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electrical contacts between nano - engineered systems are expected to constitute the basic building blocks of future nano - scale electronics. however, the accurate characterization and understanding of electrical contacts at the nano - scale is an experimentally challenging task. here we employ low - temperature scanning tunneling spectroscopy to investigate the conductance of individual nano - contacts formed between flat pb islands and their supporting substrates. we observe a suppression of the differential tunnel conductance at small bias voltages due to dynamical coulomb blockade effects. the differential conductance spectra allow us to determine the capacitances and resistances of the electrical contacts which depend systematically on the island - - substrate contact area. calculations based on the theory of environmentally assisted tunneling agree well with the measurements.
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arxiv:1006.0333
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llm - based autonomous agents often fail to execute complex web tasks that require dynamic interaction due to the inherent uncertainty and complexity of these environments. existing llm - based web agents typically rely on rigid, expert - designed policies specific to certain states and actions, which lack the flexibility and generalizability needed to adapt to unseen tasks. in contrast, humans excel by exploring unknowns, continuously adapting strategies, and resolving ambiguities through exploration. to emulate human - like adaptability, web agents need strategic exploration and complex decision - making. monte carlo tree search ( mcts ) is well - suited for this, but classical mcts struggles with vast action spaces, unpredictable state transitions, and incomplete information in web tasks. in light of this, we develop webpilot, a multi - agent system with a dual optimization strategy that improves mcts to better handle complex web environments. specifically, the global optimization phase involves generating a high - level plan by breaking down tasks into manageable subtasks and continuously refining this plan, thereby focusing the search process and mitigating the challenges posed by vast action spaces in classical mcts. subsequently, the local optimization phase executes each subtask using a tailored mcts designed for complex environments, effectively addressing uncertainties and managing incomplete information. experimental results on webarena and miniwob + + demonstrate the effectiveness of webpilot. notably, on webarena, webpilot achieves sota performance with gpt - 4, achieving a 93 % relative increase in success rate over the concurrent tree search - based method. webpilot marks a significant advancement in general autonomous agent capabilities, paving the way for more advanced and reliable decision - making in practical environments.
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arxiv:2408.15978
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we improved the discless accretion models of wynn \ & king, considering the effects of the changing aspect due to the white dwarf spin and the variable feeding intensity caused by the asynchronism, and set up a more general spot model which is not sensitive to the different forms of these effects and can be applied for the period analysis of the optical and x - ray light curve. the spot model can produce the power spectra compatible with the observations, and its simulations limit the ratio $ p _ { spin } / p _ { orb } < 2 $ between the powers at the white dwarf spin and the binary orbital frequencies, which is a strong criterion for identification of periods. then we recognize the periods for cd ind, by cam and 1rxs j083842. 1 - 282723. the spot model reveals a complex accretion geometry in the asynchronous polars, which may indicate that the complex magnetic field causes their asynchronism. we think 1rxs j083842. 1 - 282723 is a pre - polars because of its highest asynchronism and stable light curve. giving the unstable accretion process in asynchronous polars, the period analysis of the long - term light curve will make the orbital signal prominent.
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arxiv:2011.13123
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we establish bernstein - centre type of results for the category of mod $ p $ representations of $ \ mathrm { gl } _ 2 ( \ mathbb { q } _ p ) $. we treat all the remaining open cases, which occur when $ p $ is $ 2 $ or $ 3 $. our arguments carry over for all primes $ p $. this allows us to remove the restrictions on the residual representation at $ p $ in lue pan ' s recent proof of the fontaine - - mazur conjecture for hodge - - tate representations of $ \ mathrm { gal } ( \ overline { \ mathbb q } / \ mathbb { q } ) $ with equal hodge - - tate weights.
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arxiv:2104.08948
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to every finitely generated group one can assign the conjugacy growth function that counts the number of conjugacy classes intersecting a ball of radius $ n $. results of ivanov and osin show that the conjugacy growth function may be constant even if the ( ordinary ) growth function is exponential. the aim of this paper is to provide conjectures, examples and statements that show that in " normal " cases, groups with exponential growth functions also have exponential conjugacy growth functions.
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arxiv:1003.1293
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the network trained for domain adaptation is prone to bias toward the easy - to - transfer classes. since the ground truth label on the target domain is unavailable during training, the bias problem leads to skewed predictions, forgetting to predict hard - to - transfer classes. to address this problem, we propose cross - domain moving object mixing ( cmom ) that cuts several objects, including hard - to - transfer classes, in the source domain video clip and pastes them into the target domain video clip. unlike image - level domain adaptation, the temporal context should be maintained to mix moving objects in two different videos. therefore, we design cmom to mix with consecutive video frames, so that unrealistic movements are not occurring. we additionally propose feature alignment with temporal context ( fatc ) to enhance target domain feature discriminability. fatc exploits the robust source domain features, which are trained with ground truth labels, to learn discriminative target domain features in an unsupervised manner by filtering unreliable predictions with temporal consensus. we demonstrate the effectiveness of the proposed approaches through extensive experiments. in particular, our model reaches miou of 53. 81 % on viper to cityscapes - seq benchmark and miou of 56. 31 % on synthia - seq to cityscapes - seq benchmark, surpassing the state - of - the - art methods by large margins. the code is available at : https : / / github. com / kyusik - cho / cmom.
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arxiv:2211.02307
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multi - label multi - view action recognition aims to recognize multiple concurrent or sequential actions from untrimmed videos captured by multiple cameras. existing work has focused on multi - view action recognition in a narrow area with strong labels available, where the onset and offset of each action are labeled at the frame - level. this study focuses on real - world scenarios where cameras are distributed to capture a wide - range area with only weak labels available at the video - level. we propose the method named multi - view action selection learning ( multiasl ), which leverages action selection learning to enhance view fusion by selecting the most useful information from different viewpoints. the proposed method includes a multi - view spatial - temporal transformer video encoder to extract spatial and temporal features from multi - viewpoint videos. action selection learning is employed at the frame - level, using pseudo ground - truth obtained from weak labels at the video - level, to identify the most relevant frames for action recognition. experiments in a real - world office environment using the mm - office dataset demonstrate the superior performance of the proposed method compared to existing methods. the source code is available at https : / / github. com / thanhhff / multiasl /.
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arxiv:2410.03302
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as large language models ( llms ) excel across tasks and specialized domains, scaling llms based on existing models has garnered significant attention, which faces the challenge of decreasing performance when combining disparate models. various techniques have been proposed for the aggregation of pre - trained llms, including model merging, mixture - of - experts, and stacking. despite their merits, a comprehensive comparison and synergistic application of them to a diverse model zoo is yet to be adequately addressed. in light of this research gap, this paper introduces model - glue, a holistic llm scaling guideline. first, our work starts with a benchmarking of existing llm scaling techniques, especially selective merging, and variants of mixture. utilizing the insights from the benchmark results, we formulate an optimal strategy for the selection and aggregation of a heterogeneous model zoo characterizing different architectures and initialization. our methodology involves the clustering of mergeable models and optimal merging strategy selection, and the integration of clusters through a model mixture. finally, evidenced by our experiments on a diverse llama - 2 - based model zoo, model - glue shows an average performance enhancement of 5. 61 %, achieved without additional training. codes are available at : https : / / github. com / model - glue / model - glue.
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arxiv:2410.05357
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we give a geometric classification of $ n $ - dimensional nilpotent, commutative nilpotent and anticommutative nilpotent algebras. we prove that the corresponding geometric varieties are irreducible, find their dimensions and describe explicit generic families of algebras which define each of these varieties. we show some applications of these results in the study of the length of anticommutative algebras.
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arxiv:2102.10392
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the boxicity of a graph g, denoted as box ( g ) is defined as the minimum integer t such that g is an intersection graph of axis - parallel t - dimensional boxes. a graph g is a k - leaf power if there exists a tree t such that the leaves of the tree correspond to the vertices of g and two vertices in g are adjacent if and only if their corresponding leaves in t are at a distance of at most k. leaf powers are a subclass of strongly chordal graphs and are used in the construction of phylogenetic trees in evolutionary biology. we show that for a k - leaf power g, box ( g ) \ leq k - 1. we also show the tightness of this bound by constructing a k - leaf power with boxicity equal to k - 1. this result implies that there exists strongly chordal graphs with arbitrarily high boxicity which is somewhat counterintuitive.
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arxiv:0902.3551
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generating the vortex - state superposition in a matter wave is demanded in many quantum processes such as quantum memory and quantum metrology. here we report the experimental generation of macroscopic superposition of vortex states in ultracold quantum gases. by transferring an optical vortex - state superposition to the center - of - mass rotational state of ultracold atoms using the raman coupling technique, we realize two - vortex and three - vortex superposition states in quantum gases, demonstrating the high dimensionality of the vortex state. we show the controllability of the superposition states on the bloch sphere. the lifetime of the vortex superposition state in quantum gases is as large as 25 ms, about two orders of magnitude longer than the storage time in atomic ensembles. this work paves the way for high dimensional quantum processing in matter waves.
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arxiv:2411.01189
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large language models appear to learn facts from the large text corpora they are trained on. such facts are encoded implicitly within their many parameters, making it difficult to verify or manipulate what knowledge has been learned. language models have recently been extended to multilingual language models ( mllms ), enabling knowledge to be learned across hundreds of languages. meanwhile, knowledge graphs contain facts in an explicit triple format, which require careful and costly curation and are only available in a few high - resource languages, restricting their research and application. to address these issues, we propose to enhance mllms with knowledge from multilingual knowledge graphs ( mlkgs ) so as to tackle language and knowledge graph tasks across many languages, including low - resource ones. specifically, we introduce a lightweight adapter set to enhance mllms with cross - lingual entity alignment and facts from mlkgs for many languages. experiments on common benchmarks show that such enhancement benefits both mllms and mlkgs, achieving : ( 1 ) comparable or improved performance for knowledge graph completion and entity alignment relative to baselines, especially for low - resource languages ( for which knowledge graphs are unavailable ) ; and ( 2 ) improved mllm performance on language understanding tasks that require multilingual factual knowledge ; all while maintaining performance on other general language tasks.
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arxiv:2210.13617
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recently, hamiltonian neural networks ( hnn ) have been introduced to incorporate prior physical knowledge when learning the dynamical equations of hamiltonian systems. hereby, the symplectic system structure is preserved despite the data - driven modeling approach. however, preserving symmetries requires additional attention. in this research, we enhance hnn with a lie algebra framework to detect and embed symmetries in the neural network. this approach allows to simultaneously learn the symmetry group action and the total energy of the system. as illustrating examples, a pendulum on a cart and a two - body problem from astrodynamics are considered.
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arxiv:2301.07928
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multi - gap rpc prototypes with readout on a multi - strip electrode were developed for the small polar angle region of the cbm - tof subdetector, the most demanding zone in terms of granularity and counting rate. the prototypes are based on low resistivity ( $ \ sim $ 10 $ ^ { 10 } $ $ \ omega $ cm ) glass electrodes for performing in high counting rate environment. the strip width / pitch size was chosen such to fulfill the impedance matching with the front - end electronics and the granularity requirements of the innermost zone of the cbm - tof wall. the in - beam tests using secondary particles produced in heavy ion collisions on a pb target at sis18 - gsi darmstadt and sps - cern were focused on the performance of the prototype in conditions similar to the ones expected at sis100 / fair. an efficiency larger than 98 \ % and a system time resolution in the order of 70 ~ - ~ 80 ~ ps were obtained in high counting rate and high multiplicity environment.
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arxiv:1605.02558
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a basic problem for the constant dimension subspace coding is to determine the maximal possible size a _ q ( n, d, k ) of a set of k - dimensional subspaces in fnq such that the subspace distance satisfies d ( u, v ) > or = d for any two different subspaces u andv in this set. we present two new constructions of constant dimension subspace codes using subsets of maximal rank - distance ( mrd ) codes in several blocks. this method is firstly applied to the linkage construction and secondly to arbitrary number of blocks of lifting mrd codes. in these two constructions, subsets of mrd codes with bounded ranks play an essential role. the delsarte theorem of the rank distribution of mrd codes is an important ingredient to count codewords in our constructed constant dimension subspace codes. we give many new lower bounds for a _ q ( n, d, k ). more than 110 new constant dimension subspace codes better than previously best known codes are constructed.
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arxiv:1908.03804
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