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we investigate the possibility of viable leptogenesis in an appealing $ \ delta ( 27 ) $ model with a universal texture zero in the ( 1, 1 ) entry. the model accommodates the mass spectrum, mixing and cp phases for both quarks and leptons and allows for grand unification. flavoured boltzmann equations for the lepton asymmetries are solved numerically, taking into account both $ n _ 1 $ and $ n _ 2 $ right - handed neutrino decays. the $ n _ 1 $ - dominated scenario is successful and the most natural option for the model, with $ m _ 1 \ in [ 10 ^ 9, 10 ^ { 12 } ] $ gev, and $ m _ 1 / m _ 2 \ in [ 0. 002, 0. 1 ] $, which constrains the parameter space of the underlying model and yields lower bounds on the respective yukawa couplings. viable leptogenesis is also possible in the $ n _ 2 $ - dominated scenario, with the asymmetry in the electron flavour protected from $ n _ 1 $ washout by the texture zero. however, this occurs in a region of parameter space which has a stronger mass hierarchy $ m _ 1 / m _ 2 < 0. 002 $, and $ m _ 2 $ relatively close to $ m _ 3 $, which is not a natural expectation of the $ \ delta ( 27 ) $ model. | arxiv:1904.10545 |
surface engineering is the sub - discipline of materials science which deals with the surface of solid matter. it has applications to chemistry, mechanical engineering, and electrical engineering ( particularly in relation to semiconductor manufacturing ). solids are composed of a bulk material covered by a surface. the surface which bounds the bulk material is called the surface phase. it acts as an interface to the surrounding environment. the bulk material in a solid is called the bulk phase. the surface phase of a solid interacts with the surrounding environment. this interaction can degrade the surface phase over time. environmental degradation of the surface phase over time can be caused by wear, corrosion, fatigue and creep. surface engineering involves altering the properties of the surface phase in order to reduce the degradation over time. this is accomplished by making the surface robust to the environment in which it will be used. it provides a cost - effective material for robust design. a spectrum of topics that represent the diverse nature of the field of surface engineering includes plating technologies, nano and emerging technologies and surface engineering, characterization and testing. = = applications = = surface engineering techniques are being used in the automotive, aerospace, missile, power, electronic, biomedical, textile, petroleum, petrochemical, chemical, steel, cement, machine tools and construction industries including road surfacing. surface engineering techniques can be used to develop a wide range of functional properties, including physical, chemical, electrical, electronic, magnetic, mechanical, wear - resistant and corrosion - resistant properties at the required substrate surfaces. almost all types of materials, including metals, ceramics, polymers, and composites can be coated on similar or dissimilar materials. it is also possible to form coatings of newer materials ( e. g., met glass. beta - c3n4 ), graded deposits, multi - component deposits etc. the advanced materials and deposition processes including recent developments in ultra hard materials like bam ( almgb compound ) are fully covered in a recent book [ r. chattopadhyay : green tribology, green surface engineering and global warming, asm international, usa, 2014 ] in 1995, surface engineering was a £10 billion market in the united kingdom. coatings, to make surface life robust from wear and corrosion, was approximately half the market. in recent years, there has been a paradigm shift in surface engineering from age - old electroplating to processes such as vapor phase deposition, diffusion, thermal spray & welding using heat sources, such as, laser, plasma, solar beam. microwave ; friction. pulsed combustion | https://en.wikipedia.org/wiki/Surface_engineering |
we obtain coincidence rates for passive optical interferometry by exploiting the permutational symmetries of partially distinguishable input photons, and our approach elucidates qualitative features of multi - photon coincidence landscapes. we treat the interferometer input as a product state of any number of photons in each input mode with photons distinguished by their arrival time. detectors at the output of the interferometer count photons from each output mode over a long integration time. we generalize and prove the claim of tillmann et al. [ phys. rev. x 5 041015 ( 2015 ) ] that coincidence rates can be elegantly expressed in terms of immanants. immanants are functions of matrices that exhibit permutational symmetries and the immanants appearing in our coincidence - rate expressions share permutational symmetries with the input state. our results are obtained by employing representation theory of the symmetric group to analyze systems of arbitrary number of photons in arbitrarily sized interferometers. | arxiv:1709.06615 |
1 ) in 1976, looking at simple finite - dimensional complex lie superalgebras, j. ~ bernstein and i, and independently m. ~ duflo, observed that certain divergence - free vectorial lie superalgebras have deformations with odd parameters and conjectured that other simple lie superalgebras have no such deformations ( unpublished ). here, i prove this conjecture and overview the known classification of simple finite - dimensional complex lie superalgebras, their presentations, realizations, and ( very sketchily ) relations with simple lie ( super ) algebras over fields of positive characteristic. 2 ) any supermanifold which is a ringed space of the form ( a manifold $ m $, the sheaf of sections of the exterior algebra of a vector bundle over $ m $ ) is called split. gaw \ c { e } dzki ( 1977 ) and batchelor ( 1979 ) proved that every smooth supermanifolds is split. in 1982, p. green and palamodov showed that a ~ complex - analytic supermanifold can be non - split, i. e., not diffeomorphic to a split supermanifold. so far, researchers considered, mostly, even obstructions to splitness. this lead them to the conclusion that any supermanifolds of superdimension $ m | 1 $ is split. i ' ll show that there are non - split supermanifolds of superdimension $ m | 1 $ ; for example, certain $ 1 | 1 $ - dimensional superstrings, the obstructions to their splitness correspond to odd parameters. | arxiv:2210.17096 |
galaxy evolution emerges from the balance between cosmic gas accretion, fueling star formation, and supernova ( sn ) feedback, regulating the metal enrichment. hence, the stellar mass ( $ m _ * $ ) - gas metallicity relation ( mzr ) is key to understanding the physics of galaxies. high - quality jwst data enable accurate measurements of the mzr up to redshift z = 10. our aims are to understand the observed mzr, its connection with the star formation rate ( sfr ), the role played by sfr stochasticity, and how it is regulated by sn feedback. we compare the mzr from the jades, ceers, and uncover surveys, which comprise about 180 galaxies at $ z = 3 - 10 $ with $ 10 ^ 6 < m _ * / m _ \ odot < 10 ^ { 10 } $, with 200 galaxies from the serra cosmological simulations. to interpret the mzr, we develop a minimal model for galaxy evolution that includes : cosmic accretion modulated with an amplitude $ a _ { 100 } $ on 100 myr ; a time delay $ t _ d $ between sfr and sn ; sn - driven outflows with a varying mass loading factor $ \ epsilon _ { sn } $. using our minimal model, we find the observed mean mzr is reproduced by weak outflows ( $ \ epsilon _ { sn } = 1 / 4 $ ), in line with findings from jades. matching the observed mzr dispersion requires $ t _ d = 20 $ myr and a $ a _ { 100 } = 1 / 3 $ modulation of the accretion rate. successful models have low stochasticity ( $ \ sigma _ { sfr } = 0. 2 $ ), yielding a mzr dispersion of $ \ sigma _ { z } = 0. 2 $. such values are close but lower than serra predictions ( $ \ sigma _ { sfr } = 0. 24 $, $ \ sigma _ { z } = 0. 3 $ ), clarifying why serra shows flatter trend and some tension with the observations. as the mzr is very sensitive to sfr stochasticity, models predicting high r. m. s. values ( $ \ sigma _ { sfr } = 0. 5 $ ) result in a ` ` chemical chaos ' ' ( i. e. $ | arxiv:2408.00061 |
feature selection is generally used as one of the most important preprocessing techniques in machine learning, as it helps to reduce the dimensionality of data and assists researchers and practitioners in understanding data. thereby, by utilizing feature selection, better performance and reduced computational consumption, memory complexity and even data amount can be expected. although there exist approaches leveraging the power of deep neural networks to carry out feature selection, many of them often suffer from sensitive hyperparameters. this paper proposes a feature mask module ( fm - module ) for feature selection based on a novel batch - wise attenuation and feature mask normalization. the proposed method is almost free from hyperparameters and can be easily integrated into common neural networks as an embedded feature selection method. experiments on popular image, text and speech datasets have shown that our approach is easy to use and has superior performance in comparison with other state - of - the - art deep - learning - based feature selection methods. | arxiv:2010.13631 |
computed tomography ( ct ) is critical for various clinical applications, e. g., radiotherapy treatment planning and also pet attenuation correction. however, ct exposes radiation during acquisition, which may cause side effects to patients. compared to ct, magnetic resonance imaging ( mri ) is much safer and does not involve any radiations. therefore, recently, researchers are greatly motivated to estimate ct image from its corresponding mr image of the same subject for the case of radiotherapy planning. in this paper, we propose a data - driven approach to address this challenging problem. specifically, we train a fully convolutional network to generate ct given an mr image. to better model the nonlinear relationship from mri to ct and to produce more realistic images, we propose to use the adversarial training strategy and an image gradient difference loss function. we further apply autocontext model to implement a context - aware generative adversarial network. experimental results show that our method is accurate and robust for predicting ct images from mri images, and also outperforms three state - of - the - art methods under comparison. | arxiv:1612.05362 |
electronically assisted astronomy consists in capturing deep sky images with a digital camera coupled to a telescope to display views of celestial objects that would have been invisible through direct observation. this practice generates a large quantity of data, which may then be enhanced with dedicated image editing software after observation sessions. in this study, we show how image quality assessment can be useful for automatically rating astronomical images, and we also develop a dedicated model by using automated machine learning. | arxiv:2311.10617 |
based on the degeneracy of the d _ { zx } and d _ { yz } orbitals in sr _ 2ruo _ 4 it is argued that the cooper pairs condense in orbital singlets. together with the spin - triplet wave functions the real - space wave function then is symmetric. considering interaction effects the order parameter is found to have a _ { 1g } symmetry consistent with a number of experimental observations. the sensitivity of the material on non - magnetic impurities follows in a straightforward manner from the orbital - singlet configuration. | arxiv:cond-mat/0208301 |
we study the mathematical structure of superoperators describing quantum measurements, including the \ emph { entangling measurement } - - the generalization of the standard quantum measurement that results in entanglement between the measurable system and apparatus. it is shown that the coherent information can be effectively used for the analysis of such entangling measurements whose possible applications are discussed as well. | arxiv:quant-ph/0306120 |
an analytical form of the characteristic equation for a vertically mounted cantilever beam with an end rigid body is obtained and solved for the eigenvalues of the structure. the effect of the weight of the structure is taken into consideration by estimating the load as a function of the length of the beam. the mass, rotary inertia and eccentricity of the end rigid body are demonstrated to considerably affect the eigenvalues of the structure. | arxiv:1401.3212 |
the energy efficiency and power of a quantum thermoelectric system with multiple electric currents and only one heat currents are studied. the system is connected to the hot heat bath with one terminal but the cold bath with multiple terminals or vice versal. we find that the cooperative effects can be a potentially useful tool in improving the energy efficiency and output power in multi - terminal mesoscopic thermoelectric systems. as an example, we show that the cooperation between the two thermoelectric effects in three - terminal thermoelectric systems leads to markedly improved performance of heat engine within the linear response regime using the landauer - b \ " { u } tiker formalism. such improvement also emerge in four - terminal thermoelectric heat engines with three output electric currents. cooperative effects in these multi - terminal thermoelectric systems can significantly enlarge the physical parameter region with high efficiency and power. for refrigeration, we find that the energy efficiency can also be substantially improved if multi - terminal configurations are considered, suggesting a useful scheme toward electronic cooling. our study illustrates cooperative effects as a convenient approach toward high - performance thermoelectric energy conversion in multi - terminal mesoscopic systems. | arxiv:1911.11421 |
this paper presents a brief study on connections on fiber, principal and vector smooth bundles as well as some relations with their curvatures. | arxiv:2207.06542 |
as wireless communication systems look intently to compose the transition from voice communication to interactive internet data, achieving higher bit rates becomes both increasingly desirable and challenging. space - time coding ( stc ) is a communications technique for wireless systems that inhabit multiple transmit antennas and single or multiple receive antennas. space - time codes make use of advantage of both the spatial diversity provided by multiple antennas and the temporal diversity available with time - varying fading. space - time codes can be divided into block codes and trellis codes. space - time trellis coding merges signal processing at the receiver with coding techniques appropriate to multiple transmit antennas. the advantages of space - time codes ( stc ) make it extremely remarkable for high - rate wireless applications. initial stc research efforts focused on narrowband flat - fading channels. the decoding complexity of space - time turbo codes sttc increases exponentially as a function of the diversity level and transmission rate. this proposed paper provides an over view on various techniques used for the design of space - time turbo codes. this paper also discusses the techniques handled by researchers to built encoder and decoder section for multiple transmits and receives antennas. in addition the future enhancement gives a general idea for improvement and development of various codes which will involve implementing viterbi decoder with soft decoding in a multi - antenna scenario. in addition the space - time code may be analyzed using some of the available metrics and finally to simulate it for different receive antenna configurations. | arxiv:1004.1707 |
we discuss pycnonuclear burning of highly exotic atomic nuclei in deep crusts of neutron stars, at densities up to 1e13 g / cc. as an application, we consider pycnonuclear burning of matter accreted on a neutron star in a soft x - ray transient ( sxt, a compact binary containing a neutron star and a low - mass companion ). the energy released in this burning, while the matter sinks into the stellar crust under the weight of newly accreted material, is sufficient to warm up the star and initiate neutrino emission in its core. the surface thermal radiation of the star in quiescent states becomes dependent of poorly known equation of state ( eos ) of supranuclear matter in the stellar core, which gives a method to explore this eos. four qualitatively different model eoss are tested against observations of sxts. they imply different levels of the enhancement of neutrino emission in massive neutron stars by ( 1 ) the direct urca process in nucleon / hyperon matter ; ( 2 ) pion condensates ; ( 3 ) kaon condensates ; ( 4 ) cooper pairing of neutrons in nucleon matter with the forbidden direct urca process. a low level of the thermal quiescent emission of two sxts, sax j1808. 4 - 3658 and cen x - 4, contradicts model ( 4 ). observations of sxts test the same physics of dense matter as observations of thermal radiation from cooling isolated neutron stars, but the data on sxts are currently more conclusive. | arxiv:astro-ph/0501653 |
the conventional decomposition of a vector field into longitudinal ( potential ) and transverse ( vortex ) components ( helmholtz ' s theorem ) is claimed in [ 1 ] to be inapplicable to the time - dependent vector fields and, in particular, to the retarded solutions of maxwell ' s equations. because of this, according to [ 1 ], a number of conclusions drawn in [ 2 ] on the basis of the helmholtz theorem turns out to be erroneous. the helmholtz theorem is proved in this letter to hold for arbitrary vector field, both static and time - dependent. therefore, the conclusions of the paper [ 2 ] questioned in [ 1 ] are true. the validity of helmholtz ' s theorem in the general case is due to the fact that the decomposition above of vector field does not influence the field time coordinate, which plays, thus, a passive role in the decomposition procedure. an analysis is given of the mistakes made in [ 1 ]. it is noted that for point particle the longitudinal and transverse components of electric field, taken separately, are characterized by the infinitely great velocity of propagation. however, superluminal contributions to the expression for the total electric field cancel each other. | arxiv:quant-ph/0311124 |
the extraction of detailed nuclear structure information from transfer reactions requires reliable, well - normalized data as well as optical potentials and a theoretical framework demonstrated to work well in the relevant mass and beam energy ranges. it is rare that the theoretical ingredients can be tested well for exotic nuclei owing to the paucity of data. the halo nucleus be - 11 has been examined through the 10be ( d, p ) reaction in inverse kinematics at equivalent deuteron energies of 12, 15, 18, and 21. 4 mev. elastic scattering of be - 10 on protons was used to select optical potentials for the analysis of the transfer data. additionally, data from the elastic and inelastic scattering of be - 10 on deuterons was used to fit optical potentials at the four measured energies. transfers to the two bound states and the first resonance in be - 11 were analyzed using the finite range adiabatic wave approximation ( fr - adwa ). consistent values of the spectroscopic factor of both the ground and first excited states were extracted from the four measurements, with average values of 0. 71 ( 5 ) and 0. 62 ( 4 ) respectively. the calculations for transfer to the first resonance were found to be sensitive to the size of the energy bin used and therefore could not be used to extract a spectroscopic factor. | arxiv:1311.3205 |
we propose a simple robust hypothesis test that has the same sample complexity as that of the optimal neyman - pearson test up to constants, but robust to distribution perturbations under hellinger distance. we discuss the applicability of such a robust test for estimating distributions in hellinger distance. we empirically demonstrate the power of the test on canonical distributions. | arxiv:2011.01848 |
ultra - diffuse galaxies ( udgs ) are attractive candidates to probe cosmological models and test theories of galaxy formation at low masses ; however, they are difficult to detect because of their low surface brightness. in the local group a handful of udgs have been found to date, most of which are satellites of the milky way and m31, and only two are isolated galaxies. it is unclear whether so few udgs are expected. we address this by studying the population of udgs formed in hydrodynamic constrained simulations of the local group from the hestia suite. for a local group with a total enclosed mass $ m _ { \ rm lg } \! \ left ( < 2. 5 \, { \ rm mpc } \ right ) = 8 \ times10 ^ { 12 } \, { \ rm m _ \ odot } $, we predict that there are $ 12 \ pm3 $ isolated udgs ( 68 % confidence ) with stellar masses $ 10 ^ 6 \ leq m _ \ ast \, / \, { \ rm m _ \ odot } < 10 ^ 9, $ and effective radii $ r _ { \ rm e } \ geq 1. 5 \, { \ rm kpc } $, within 2. 5 mpc of the local group, of which $ 2 ^ { + 2 } _ { - 1 } $ ( 68 % confidence ) are detectable in the footprint of the sloan digital sky survey ( sdss ). accounting for survey incompleteness, we find that almost the entire population of udgs in the local group field would be observable in a future all - sky survey with a depth similar to the sdss, the dark energy survey, or the legacy survey of space and time. our results suggest that there is a population of udgs in the local group awaiting discovery. | arxiv:2212.05066 |
given an ascending chain $ ( i _ n ) _ { n \ in \ mathbb { n } } $ of $ \ sym $ - invariant squarefree monomial ideals, we study the corresponding chain of alexander duals $ ( i _ n ^ \ vee ) _ { n \ in \ mathbb { n } } $. using a novel combinatorial tool, which we call \ emph { avoidance up to symmetry }, we provide an explicit description of the minimal generating set up to symmetry in terms of the original generators. combining this result with methods from discrete geometry, this enables us to show that the number of orbit generators of $ i _ n ^ \ vee $ is given by a polynomial in $ n $ for sufficiently large $ n $. the same is true for the number of orbit generators of minimal degree, this degree being a linear function in $ n $ eventually. the former result implies that the number of $ \ sym $ - orbits of primary components of $ i _ n $ grows polynomially in $ n $ for large $ n $. as another application, we show that, for each $ i \ geq 0 $, the number of $ i $ - dimensional faces of the associated stanley - reisner complexes of $ i _ n $ is also given by a polynomial in $ n $ for large $ n $. | arxiv:2209.14132 |
the thermal properties of light mesons, including the temperature dependence of their masses ( both screening and pole masses ) and thermal widths, are studied in a two - flavor ( $ n _ f = 2 $ ) soft - wall ads / qcd model. by solving the spatial correlation functions, we extract the screening masses ( $ m _ { \ rm { scr } } $ ) from their poles. the screening masses of pseudo - scalar ( $ \ pi $ ) and axial - vector ( $ a _ 1 $ ) mesons increase almost monotonously with the increase of temperature. the screening masses of scalar ( $ \ sigma $ ) and vector ( $ \ rho $ ) mesons decrease at low temperature and increase at high temperature. the pole masses ( $ m _ { \ rm { pole } } $ ) and the thermal widths ( $ \ gamma $ ) are extracted from the temporal correlation functions and the corresponding spectral functions. the results indicate that the pole masses have local minima at low temperature and increase at high temperature. the thermal widths increase rapidly above the chiral crossover temperature $ t _ { cp } $, indicating the dissociations of mesons at high temperature. furthermore, the degeneration of the chiral partners ( $ \ pi $ and $ \ sigma $, $ \ rho $ and $ a _ 1 $ ) above $ t _ { cp } $ is observed from the screening and pole masses, revealing the chiral symmetry restoration at the hadronic spectrum level. finally, we numerically verify that the spectral functions in the temporal regime are strongly related to the quasi - normal modes with complex frequencies $ \ omega _ 0 = m _ { \ rm { pole } } - i \ gamma / 2 $. | arxiv:2102.10946 |
exact string solutions are presented, providing backgrounds where a dynamical change of topology is occuring. this is induced by the time variation of a modulus field. some lessons are drawn concerning the region of validity of effective theories and how they can be glued together, using stringy information in the region where the topology changes. | arxiv:hep-th/9404092 |
in this paper, thick branes generated by the mimetic scalar field with lagrange multiplier formulation are investigated. we give three typical thick brane background solutions with different asymptotic behaviors and show that all the solutions are stable under tensor perturbations. the effective potentials of the tensor perturbations exhibit as volcano potential, po \ " { o } schl - teller potential, and harmonic oscillator potential for the three background solutions, respectively. all the tensor zero modes ( massless gravitons ) of the three cases can be localized on the brane. we also calculate the corrections to the newtonian potential. on a large scale, the corrections to the newtonian potential can be ignored. while on a small scale, the correction from the volcano - like potential is more pronounced than the other two cases. combining the specific corrections to the newtonian potential of these three cases and the latest results of short - range gravity experiments, we get the constraint on the scale parameter as $ k \ gtrsim 10 ^ { - 4 } $ ev, and constraint on the corresponding five - dimensional fundamental scale as $ m _ \ ast \ gtrsim10 ^ 5 $ tev. | arxiv:2005.08438 |
we study the semi - classical theory of wave packet dynamics in crystalline solids extended to include the effects of a non - uniform electric field. in particular, we derive a correction to the semi - classical equations of motion ( eoms ) for the dynamics of the wave packet center that depends on the gradient of the electric field and on the quantum metric ( also called the fubini - study, bures, or bloch metric ) on the brillouin zone. we show that the physical origin of this term is a contribution to the total energy of the wave packet that depends on its electric quadrupole moment and on the electric field gradient. we also derive an equation relating the electric quadrupole moment of a sharply peaked wave packet to the quantum metric evaluated at the wave packet center in reciprocal space. finally, we explore the physical consequences of this correction to the semi - classical eoms. we show that in a metal with broken time - reversal and inversion symmetry, an electric field gradient can generate a longitudinal current which is linear in the electric field gradient, and which depends on the quantum metric at the fermi surface. we then give two examples of concrete lattice models in which this effect occurs. our results show that non - uniform electric fields can be used to probe the quantum geometry of the electronic bands in metals and open the door to further studies of the effects of non - uniform electric fields in solids. | arxiv:1812.10497 |
the type ia supernova ( sn ia ) sn 2020nlb was discovered in the virgo cluster galaxy m85 shortly after explosion. here we present observations that include one of the earliest high - quality spectra and some of the earliest multi - colour photometry of a sn ia to date. we calculated that sn 2020nlb faded 1. 28 + / - 0. 02 mag in the b band in the first 15 d after maximum brightness. we independently fitted a power - law rise to the early flux in each filter, and found that the optical filters all give a consistent first light date estimate. in contrast to the earliest spectra of sn 2011fe, those of sn 2020nlb show strong absorption features from singly ionised metals, including fe ii and ti ii, indicating lower - excitation ejecta at the earliest times. these earliest spectra show some similarities to maximum - light spectra of 1991bg - like sne ia. the spectra of sn 2020nlb then evolve to become hotter and more similar to sn 2011fe as it brightens towards peak. we also obtained a sequence of nebular spectra that extend up to 594 days after maximum light, a phase out to which sne ia are rarely followed. the [ fe iii ] / [ fe ii ] flux ratio ( as measured from emission lines in the optical spectra ) begins to fall around 300 days after peak ; by the + 594 d spectrum, the ionisation balance of the emitting region of the ejecta has shifted dramatically, with [ fe iii ] by then being completely absent. the final spectrum is almost identical to sn 2011fe at a similar epoch. comparing our data to other sn ia nebular spectra, there is a possible trend where sne that were more luminous at peak tend to have a higher [ fe iii ] / [ fe ii ] flux ratio in the nebular phase, but there is a notable outlier in sn 2003hv. finally, using light - curve fitting on our data, we estimate the distance modulus for m85 to be 30. 99 + / - 0. 19 mag, corresponding to a distance of $ 15. 8 ^ { + 1. 4 } _ { - 1. 3 } $ mpc. | arxiv:2401.08759 |
we study an opinion formation model by the means of a co - evolving complex network where the vertices represent the individuals, characterised by their evolving opinions, and the edges represent the interactions among them. the network adapts to the spreading of opinions in two ways : not only connected agents interact and eventually change their thinking but an agent may also rewire one of its links to a neighborhood holding the same opinion as his. the dynamics depends on an external parameter { \ phi }, which controls the plasticity of the network. we show how the information entropy associated to the distribution of group sizes, allows to locate the phase transition between full consensus and a society where different opinions coexist. we also determine the minimum size of the most informative sampling. at the transition the distribution of the sizes of groups holding the same opinion is scale free. | arxiv:1405.7811 |
markov state models ( msm ) are widely used to elucidate dynamic properties of molecular systems from unbiased molecular dynamics ( md ). however, the implementation of reweighting schemes for msms to analyze biased simulations, for example produced by enhanced sampling techniques, is still at an early stage of development. several dynamical reweighing approaches have been proposed, which can be classified as approaches based on ( i ) kramers rate theory, ( ii ) rescaling of the probability density flux, ( iii ) reweighting by formulating a likelihood function, ( iv ) path reweighting. we present the state - of - the - art and discuss the methodological differences of these methods, their limitations and recent applications. | arxiv:1910.07894 |
we present a quasi - analytical solution of a spin - orbital model of kcuf $ _ { 3 } $, using the variational method for green ' s functions. by analyzing the spectra for different partial bosonic compositions as well as the full solution, we show that hole propagation needs both orbiton and magnon excitations to develop, but the orbitons dominate the picture. we further elucidate the role of the different bosons by analyzing the self - energies for simplified models, establishing that because of the nature of the spin - orbital ground state, magnons alone do not produce a full quasiparticle band, in contrast to orbitons. finally, using the electron - hole transformation between the $ e _ g $ states of kcuf $ _ 3 $ and lamno $ _ 3 $ we suggest the qualitative scenario for photoemission experiments in lamno $ _ 3 $. | arxiv:1706.06071 |
the leading - order effect of interactions on a homogeneous bose gas is theoretically predicted to shift the critical temperature by an amount \ delta \ tc = # a _ { scatt } n ^ { 1 / 3 } t _ 0 from the ideal gas result t _ 0, where a _ { scatt } is the scattering length and n is the density. there have been several different theoretical estimates for the numerical coefficient #. we claim to settle the issue by measuring the numerical coefficient in a lattice simulation of o ( 2 ) phi ^ 4 field theory in three dimensions - - - an effective theory which, as observed previously in the literature, can be systematically matched to the dilute bose gas problem to reproduce non - universal quantities such as the critical temperature. we find # = 1. 32 + - 0. 02. | arxiv:cond-mat/0103228 |
the su - schrieffer - heeger ( ssh ) model, a prime example of a one - dimensional topologically nontrivial insulator, has been extensively studied in flat space - time. in recent times, many studies have been conducted to understand the properties of the low - dimensional quantum matter in curved spacetime, which can mimic the gravitational event horizon and black hole physics. however, the impact of curved spacetime on the topological properties of such systems remains unexplored. here, we investigate the curved spacetime ( cst ) version of the ssh model by introducing a position - dependent hopping parameter. we show, using different topological markers, that the cst - ssh model can undergo a topological phase transition. we find that the topologically non - trivial phase can host zero - energy edge modes, but those edge modes are asymmetric, unlike the usual ssh model. moreover, we find that at the topological transition point, a critical slowdown takes place for zero - energy wave packets near the boundary, indicating the presence of a horizon, and interestingly, if one moves even a slight distance away from the transition point, wave packets start bouncing back and reverse the direction before reaching the horizon. a semiclassical description of the wave packet trajectories also supports these results. | arxiv:2504.16200 |
the millimeter / submillimeter wavelength polarization of sgr a * is known to be variable in both magnitude and position angle on time scales down to a few hours. the unstable polarization has prevented measurements made at different frequencies and different epochs from yielding convincing measurements of faraday rotation in this source. here we present observations made with the submillimeter array polarimeter at 227 and 343 ghz with sufficient sensitivity to determine the rotation measure at each band without comparing position angles measured at separate epochs. we find the 10 - epoch mean rotation measure to be ( - 5. 6 + / - 0. 7 ) x10 ^ 5 rad / m ^ 2 ; the measurements are consistent with a constant value. we conservatively assign a 3sigma upper limit of 2x10 ^ 5 rad / m ^ 2 to rotation measure changes, which limits accretion rate fluctuations to 25 %. this rotation measure detection limits the accretion rate to less than 2x10 ^ - 7 m _ sun / yr if the magnetic field is near equipartition, ordered, and largely radial, while a lower limit of 2x10 ^ - 9 m _ sun / yr holds even for a sub - equipartition, disordered, or toroidal field. the mean intrinsic position angle is 167 + / - 7 degrees and we detect variations of 31 ( + 18 / - 9 ) degrees. these variations must originate in the submillimeter photosphere, rather than arising from rotation measure changes. | arxiv:astro-ph/0611791 |
in the independent set problem, the input is a graph $ g $, every vertex has a non - negative integer weight, and the task is to find a set $ s $ of pairwise non - adjacent vertices, maximizing the total weight of the vertices in $ s $. we give an $ n ^ { o ( \ log ^ 2 n ) } $ time algorithm for this problem on graphs excluding the path $ p _ 6 $ on $ 6 $ vertices as an induced subgraph. currently, there is no constant $ k $ known for which independent set on $ p _ { k } $ - free graphs becomes np - complete, and our result implies that if such a $ k $ exists, then $ k > 6 $ unless all problems in np can be decided in ( quasi ) polynomial time. using the combinatorial tools that we develop for the above algorithm, we also give a polynomial - time algorithm for efficient dominating set on $ p _ 6 $ - free graphs. in this problem, the input is a graph $ g $, every vertex has an integer weight, and the objective is to find a set $ s $ of maximum weight such that every vertex in $ g $ has exactly one vertex in $ s $ in its closed neighborhood, or to determine that no such set exists. prior to our work, the class of $ p _ 6 $ - free graphs was the only class of graphs defined by a single forbidden induced subgraph on which the computational complexity of efficient dominating set was unknown. | arxiv:1507.02163 |
vapor transportation is the core process in growing transition - metal dichalcogenides ( tmdcs ) by chemical vapor deposition ( cvd ). one inevitable problem is the spatial inhomogeneity of the vapors. the non - stoichiometric supply of transition - metal precursors and chalcogen leads to poor control in products ' location, morphology, crystallinity, uniformity and batch to batch reproducibility. while vapor - liquid - solid ( vls ) growth involves molten precursors at the growth temperatures higher than their melting points. the liquid sodium molybdate can precipitate solid mos2 monolayers when saturated with sulfur vapor. taking advantage of the vls growth, we achieved three kinds of important achievements : ( a ) 4 - inch - wafer - scale uniform growth of mos2 flakes on sio2 / si substrates, ( b ) 2 - inch - wafer - scale growth of continuous mos2 film with a grain size exceeding 100 um on sapphire substrates, and ( c ) pattern ( site - controlled ) growth of mos2 flakes and film. we clarified that the vls growth thus pave the new way for the high - efficient, scalable synthesis of two - dimensional tmdc monolayers. | arxiv:1906.05436 |
a novel evolutionary approach for explainable artificial intelligence is presented : the " evolved explanations " model ( evex ). this methodology consists in combining local interpretable model agnostic explanations ( lime ) with multi - objective genetic algorithms to allow for automated segmentation parameter tuning in image classification tasks. in this case, the dataset studied is patch - camelyon, comprised of patches from pathology whole slide images. a publicly available convolutional neural network ( cnn ) was trained on this dataset to provide a binary classification for presence / absence of lymph node metastatic tissue. in turn, the classifications are explained by means of evolving segmentations, seeking to optimize three evaluation goals simultaneously. the final explanation is computed as the mean of all explanations generated by pareto front individuals, evolved by the developed genetic algorithm. to enhance reproducibility and traceability of the explanations, each of them was generated from several different seeds, randomly chosen. the observed results show remarkable agreement between different seeds. despite the stochastic nature of lime explanations, regions of high explanation weights proved to have good agreement in the heat maps, as computed by pixel - wise relative standard deviations. the found heat maps coincide with expert medical segmentations, which demonstrates that this methodology can find high quality explanations ( according to the evaluation metrics ), with the novel advantage of automated parameter fine tuning. these results give additional insight into the inner workings of neural network black box decision making for medical data. | arxiv:2005.07229 |
the structure of a protein is crucial in determining its functionality, and is much more conserved than sequence during evolution. a key task in structural biology is to compare protein structures in order to determine evolutionary relationships, estimate the function of newly - discovered structures, and predict unknown structures. we propose a bayesian method for protein structure alignment, with the prior on alignments based on functions which penalise ` ` gaps ' ' in the aligned sequences. we show how a broad class of penalty functions fits into this framework, and how the resulting posterior distribution can be efficiently sampled. a commonly - used gap penalty function is shown to be a special case, and we propose a new penalty function which alleviates an undesirable feature of the commonly - used penalty. we illustrate our method on benchmark data sets, and find it competes well with popular tools from computational biology. our method has the benefit of being able to potentially explore multiple competing alignments and quantify their merits probabilistically. the framework naturally allows for further information such as amino acid sequence to be included, and could be adapted to other situations such as flexible proteins or domain swaps. | arxiv:1404.1556 |
the influence of nonperturbative fields on instantons in quantum chromodynamics is studied. effective action for instanton is derived in bilocal approximation and it is demonstrated that stochastic background gluon fields are responsible for ir stabilization of instantons. it is shown that instanton size in qcd is of order of 0. 25 fm. comparison of obtained instanton size distribution with lattice data is made. | arxiv:hep-ph/0111305 |
we calculate that an appropriate modification of the field associated with only one of the photons of a photon pair can suppress generation of the pair entirely. from this general result, we develop a method for suppressing the generation of undesired photon pairs utilizing photonic stop bands. for a third - order nonlinear optical source of frequency - degenerate photons we calculate the modified frequency spectrum ( joint spectral intensity ) and show a significant increase in a standard metric, the coincidence to accidental ratio. these results open a new avenue for photon - pair frequency correlation engineering. | arxiv:1609.00106 |
identifying the entire set of complexes is essential not only to understand complex formations, but also to map the high level organisation of the cell. computational prediction of protein complexes faces several challenges including the lack of sufficient protein interactions, presence of noise in protein interaction datasets and difficulty in predicting small and sparse complexes. these challenges are covered in most reviews of complex prediction methods. however, an important challenge that needs to be addressed is the prediction of membrane complexes. these are often ignored because existing protein interaction detection techniques do not detect interactions between membrane proteins. but, recently there have been several new experimental techniques including my2h that are capable of detecting membrane protein interactions. in the light of this new data, we discuss here new challenges and the kind of open problems that need to be solved to effectively detect membrane complexes. | arxiv:1506.01863 |
we show that the probability mass function of the riff - shuffle distribution, also known as the minimum negative binomial distribution, is unimodal, but in general not log - concave. | arxiv:math/0702639 |
the transition between the hadronic phase and the quark gluon plasma phase at nonzero temperature and quark chemical potentials is studied within the large - nc expansion of qcd. | arxiv:hep-th/0501069 |
dp - coloring ( also called correspondence coloring ) is a generalization of list coloring that has been widely studied in recent years after its introduction by dvo \ v { r } \ ' { a } k and postle in 2015. as the analogue of the chromatic polynomial $ p ( g, m ) $, the dp color function of a graph $ g $, denoted $ p _ { dp } ( g, m ) $, counts the minimum number of dp - colorings over all possible $ m $ - fold covers. chromatic polynomials for joins and vertex - gluings of graphs are well understood, but the effect of these graph operations on the dp color function is not known. in this paper we make progress on understanding the dp color function of the join of a graph with a complete graph and vertex - gluings of certain graphs. we also develop tools to study the dp color function under these graph operations, and we study the threshold ( smallest $ m $ ) beyond which the dp color function of a graph constructed with these operations equals its chromatic polynomial. | arxiv:2104.12268 |
we present a python module for simulating silicon photo - multipliers, avalanche photo - diodes, and multi - pixel photon counters. this module allows users to perform noise analyses : dark count rate, crosstalk, and afterpulsing. furthermore, the simulation framework novelty is the capability of simulating assemblies of sipm arrays ( mppca ) for large area detectors like ring imaging cherenkov detectors, cherenkov telescopes, positron emission tomography, and any detector using sipm arrays. users can simulate ring - or shower - like - shaped signals based on the expected number of photons generated by the source. we validate the performance of the simulation module with data from four different sipm : broadcom afbr - s4n66p024m, hamamatsu s14160 - 636050hs, onsemi microfc - 60035, and fbk nuv - hd3. | arxiv:2411.16710 |
in this paper, we investigate the delay - aware dynamic resource management problem for multi - service transmission in high - speed railway wireless communications, with a focus on resource allocation among the services and power control along the time. by taking account of average delay requirements and power constraints, the considered problem is formulated into a stochastic optimization problem, rather than pursuing the traditional convex optimization means. inspired by lyapunov optimization theory, the intractable stochastic optimization problem is transformed into a tractable deterministic optimization problem, which is a mixed - integer resource management problem. by exploiting the specific problem structure, the mixed - integer resource management problem is equivalently transformed into a single variable problem, which can be effectively solved by the golden section search method with guaranteed global optimality. finally, we propose a dynamic resource management algorithm to solve the original stochastic optimization problem. simulation results show the advantage of the proposed dynamic algorithm and reveal that there exists a fundamental tradeoff between delay requirements and power consumption. | arxiv:1601.01526 |
in this paper, we study the covariant duffin - kemmer - petiau ( dkp ) equation in the space - time generated by a cosmic string and we examine the linear interaction of a dkp field with gravitational fields produced by topological defects and thus study the influence of topology on this system. we highlight two classes of solutions defined by the product of the deficit angle with the angular velocity of the rotating frame. we solve the covariant form of dkp equation in an exact analytical manner for node - less and one - node states by means of an appropriate ansatz. | arxiv:1607.01418 |
common deep learning models for 3d environment perception often use pillarization / voxelization methods to convert point cloud data into pillars / voxels and then process it with a 2d / 3d convolutional neural network ( cnn ). the pioneer work pointnet has been widely applied as a local feature descriptor, a fundamental component in deep learning models for 3d perception, to extract features of a point cloud. this is achieved by using a symmetric max - pooling operator which provides unique pillar / voxel features. however, by ignoring most of the points, the max - pooling operator causes an information loss, which reduces the model performance. to address this issue, we propose a novel local feature descriptor, mini - pointnetplus, as an alternative for plug - and - play to pointnet. our basic idea is to separately project the data points to the individual features considered, each leading to a permutation invariant. thus, the proposed descriptor transforms an unordered point cloud to a stable order. the vanilla pointnet is proved to be a special case of our mini - pointnetplus. due to fully utilizing the features by the proposed descriptor, we demonstrate in experiment a considerable performance improvement for 3d perception. | arxiv:2307.13300 |
a renewed attempt to detect radio recombination lines from external galaxies has resulted in the measurement of lines from several bright starburst galaxies. the lines are produced by hydrogen ionized by young, high - mass stars and are diagnostic of the conditions and gas dynamics in the starburst regions without problems of dust obscuration. we present here detections of the lines h91alpha and h92alpha near 8. 6 ghz from the starburst nuclei in ngc 3256, ngc 4945, and the circinus galaxy using the atca and vla. modelling the line emitting region as a collection of h ii regions, we derive the required number of h ii regions, their temperature, density, and distribution. | arxiv:astro-ph/0411115 |
bose - - einstein condensates have been recently proposed as dark matter candidates. in order to characterise the phenomenology associated to such models, we extend previous investigations by studying the most general case of a relativistic bec on a curved background including a non - minimal coupling to curvature. in particular, we discuss the possibility of a two phase cosmological evolution : a cold dark matter - like phase at the large scales / early times and a condensed phase inside dark matter halos. during the first phase dark matter is described by a minimally coupled weakly self - interacting scalar field, while in the second one dark matter condensates and, we shall argue, develops as a consequence the non - minimal coupling. finally, we discuss how such non - minimal coupling could provide a new mechanism to address cold dark matter paradigm issues at galactic scales. | arxiv:1310.3753 |
there exist consistent low energy effective field theories describing gravity in the higgs phase that allow the coexistence of massive gravitons and the conventional 1 / r potential of gravity. in an effort to constrain the value of the graviton mass in these theories, we study the tensor contribution to the cmb temperature anisotropy and polarization spectra in the presence of a non - vanishing graviton mass. we find that the observation of a b - mode signal consistent with the spectrum predicted by inflationary models would provide the strongest limit yet on the mass of an elementary particle - - a graviton - - at a level of m \ lesssim 10 ^ ( - 30 ) ev \ approx ( 10 mpc ) ^ ( - 1 ). we also find that a graviton mass in the range between ( 10 mpc ) ^ ( - 1 ) and ( 10 kpc ) ^ ( - 1 ) leads to interesting modifications of the polarization spectrum. the characteristic signature of a graviton mass in this range would be a plateau in the b - mode spectrum up to angular multipoles of l \ sim 100. for even larger values of the graviton mass the tensor contribution to the cmb spectra becomes strongly suppressed. | arxiv:0907.1658 |
what is " intelligent " information retrieval? essentially this is asking what is intelligence, in this article i will attempt to show some of the aspects of human intelligence, as related to information retrieval. i will do this by the device of a semi - imaginary oracle. every observatory has an oracle, someone who is a distinguished scientist, has great administrative responsibilities, acts as mentor to a number of less senior people, and as trusted advisor to even the most accomplished scientists, and knows essentially everyone in the field. in an appendix i will present a brief summary of the statistical factor space method for text indexing and retrieval, and indicate how it will be used in the astrophysics data system abstract service. 2018 keywords : personal digital assistant ; supervised topic models | arxiv:1801.00815 |
using $ p $ - adic local langlands correspondence for $ \ operatorname { gl } _ 2 ( \ mathbb { q } _ p ) $, we prove that the support of patched modules constructed by caraiani, emerton, gee, geraghty, paskunas, and shin meet every irreducible component of the potentially semistable deformation ring. this gives a new proof of the breuil - m \ ' ezard conjecture for 2 - dimensional representations of the absolute galois group of $ \ mathbb { q } _ p $ when $ p > 2 $, which is new in the case $ p = 3 $ and $ \ bar { r } $ a twist of an extension of the trivial character by the mod p cyclotomic character. as a consequence, a local restriction in the proof of fontaine - mazur conjecture by kisin is removed. | arxiv:1803.07451 |
the lcdm cosmological model assumes the existence of a small cosmological constant in order to explain the observed accelerating cosmic expansion. despite the dramatic improvement of the quality of cosmological data during the last decade it remains the simplest model that fits remarkably well ( almost ) all cosmological observations. in this talk i review the increasingly successful fits provided by lcdm on recent geometric probe data of the cosmic expansion. i also briefly discuss some emerging shortcomings of the model in attempting to fit specific classes of data ( eg cosmic velocity dipole flows and cluster halo profiles ). finally, i summarize recent results on the theoretically predicted matter overdensity ( $ \ delta _ m = \ frac { \ delta \ rho _ m } { \ rho _ m } $ ) evolution ( a dynamical probe of the cosmic expansion ), emphasizing its scale and gauge dependence on large cosmological scales in the context of general relativity. a new scale dependent parametrization which describes accurately the growth rate of perturbations even on scales larger than 100h ^ { - 1 } mpc is shown to be a straightforward generalization of the well known scale independent parametrization f ( a ) = \ omms ( a ) ^ \ gamma valid on smaller cosmological scales. | arxiv:1002.3030 |
we propose a 3d generation pipeline that uses diffusion models to generate realistic human digital avatars. due to the wide variety of human identities, poses, and stochastic details, the generation of 3d human meshes has been a challenging problem. to address this, we decompose the problem into 2d normal map generation and normal map - based 3d reconstruction. specifically, we first simultaneously generate realistic normal maps for the front and backside of a clothed human, dubbed dual normal maps, using a pose - conditional diffusion model. for 3d reconstruction, we " carve " the prior smpl - x mesh to a detailed 3d mesh according to the normal maps through mesh optimization. to further enhance the high - frequency details, we present a diffusion resampling scheme on both body and facial regions, thus encouraging the generation of realistic digital avatars. we also seamlessly incorporate a recent text - to - image diffusion model to support text - based human identity control. our method, namely, chupa, is capable of generating realistic 3d clothed humans with better perceptual quality and identity variety. | arxiv:2305.11870 |
large language models ( llms ) exhibit impressive proficiency in natural language generation, understanding user instructions, and emulating human - like language use, which has led to significant interest in their application to role - playing scenarios. however, the manual collection of role - specific script data and the evaluation of model performance are resource - intensive processes. this paper introduces a prompt - based framework designed to leverage gpt ' s capabilities for the generation of role - playing dialogue datasets and the evaluation of role - playing performance. to validate the effectiveness of the gpt - based generation and evaluation, we further incorporate the recall - oriented rouge - l metric, providing an additional quantitative measure of performance. | arxiv:2406.00627 |
we introduce a new nonparametric framework for classification problems in the presence of missing data. the key aspect of our framework is that the regression function decomposes into an anova - type sum of orthogonal functions, of which some ( or even many ) may be zero. working under a general missingness setting, which allows features to be missing not at random, our main goal is to derive the minimax rate for the excess risk in this problem. in addition to the decomposition property, the rate depends on parameters that control the tail behaviour of the marginal feature distributions, the smoothness of the regression function and a margin condition. the ambient data dimension does not appear in the minimax rate, which can therefore be faster than in the classical nonparametric setting. we further propose a new method, called the hard - thresholding anova missing data ( ham ) classifier, based on a careful combination of a k - nearest neighbour algorithm and a thresholding step. the ham classifier attains the minimax rate up to polylogarithmic factors and numerical experiments further illustrate its utility. | arxiv:2305.11672 |
in this study, we explicitly calculate information and fidelity of an r - rank projective measurement on a completely unknown state in a d - dimensional hilbert space. we also show a tradeoff between information and fidelity at the level of a single outcome and discuss the efficiency of measurement with respect to fidelity. | arxiv:1109.2666 |
using the descent spectral sequence for a galois extension of ring spectra, we compute the picard group of the higher real $ k $ - theory spectra of hopkins and miller at height $ n = p - 1 $, for $ p $ an odd prime. more generally, we determine the picard groups of the homotopy fixed points spectra $ e _ n ^ { hg } $, where $ e _ n $ is lubin - tate $ e $ - theory at the prime $ p $ and height $ n = p - 1 $, and $ g $ is any finite subgroup of the extended morava stabilizer group. we find that these picard groups are always cyclic, generated by the suspension. | arxiv:1511.08064 |
we present clustervo, a stereo visual odometry which simultaneously clusters and estimates the motion of both ego and surrounding rigid clusters / objects. unlike previous solutions relying on batch input or imposing priors on scene structure or dynamic object models, clustervo is online, general and thus can be used in various scenarios including indoor scene understanding and autonomous driving. at the core of our system lies a multi - level probabilistic association mechanism and a heterogeneous conditional random field ( crf ) clustering approach combining semantic, spatial and motion information to jointly infer cluster segmentations online for every frame. the poses of camera and dynamic objects are instantly solved through a sliding - window optimization. our system is evaluated on oxford multimotion and kitti dataset both quantitatively and qualitatively, reaching comparable results to state - of - the - art solutions on both odometry and dynamic trajectory recovery. | arxiv:2003.12980 |
we propose a mathematical model to describe the athermal fluctuations of thin sheets driven by the type of random driving that might be experienced prior to weak crumpling. the model is obtained by merging the f \ " oppl - von k \ ' arm \ ' an equations from elasticity theory with techniques from out - of - equilibrium statistical physics to obtain a nonlinear strongly coupled $ \ phi ^ { 4 } $ - langevin field equation with spatially varying kernel. with the aid of the self - consistent expansion ( sce ), this equation is analytically solved for the structure factor of a fluctuating sheet. in contrast to previous research which has suggested that the structure factor follows an anomalous power - law, we find that the structure factor in fact obeys a logarithmically corrected rational function. numerical simulations of our model confirm the accuracy of our analytical solution. | arxiv:2207.04643 |
we present a detailed characterization of the growth dynamics of ga ( al ) as ( 111 ) a surfaces. we develop a theoretical growth model that well describes the observed behavior on the growth parameters and underlines the ehrlich - schwoebel barrier as leading factor that determines the growth dynamics. on such basis we analyze the factors that lead to the huge observed roughness on such surface orientations and we identify the growth conditions that drive the typical three - dimensional growth of ga ( al ) as ( 111 ) a towards atomically flat surface. gaas / algaas quantum wells realized on optimized surface ( < 0. 2 nm roughness ) show a record low emission linewidth of 4. 5 mev. | arxiv:1704.01853 |
we elucidate the intermediate of the macroscopic fluid model and the microscopic kinetic model by studying the poisson algebraic structure of the one - dimensional vlasov - poisson system. the water - bag model helps formulating the hierarchy of sub - algebras, which interpolates the gap between the fluid and kinetic models. by analyzing the embedding of the sub - manifold of an intermediate hierarchy in a more microscopic hierarchy, we characterize the microscopic effect as the symmetry breaking pertinent to a macroscopic invariant. | arxiv:2208.10891 |
in this paper we study the finite w - algebra for the queer lie superalgebra q ( n ) associated with the non - regular even nilpotent coadjoint orbits in the case when the corresponding nilpotent element has jordan blocks each of size l. we prove that this finite w - algebra is isomorphic to a quotient of the super - yangian of q ( { n / l } ) | arxiv:1705.10200 |
significant progress has been made in facial landmark detection with the development of convolutional neural networks. the widely - used algorithms can be classified into coordinate regression methods and heatmap based methods. however, the former loses spatial information, resulting in poor performance while the latter suffers from large output size or high post - processing complexity. this paper proposes a new solution, gaussian vector, to preserve the spatial information as well as reduce the output size and simplify the post - processing. our method provides novel vector supervision and introduces band pooling module to convert heatmap into a pair of vectors for each landmark. this is a plug - and - play component which is simple and effective. moreover, beyond box strategy is proposed to handle the landmarks out of the face bounding box. we evaluate our method on 300w, cofw, wflw and jd - landmark. that the results significantly surpass previous works demonstrates the effectiveness of our approach. | arxiv:2010.01318 |
based on a classic paper by ginibre [ commun. math. phys. { \ bf 8 } 26 ( 1968 ) ] it is shown that whenever bogoliubov ' s approximation, that is, the replacement of a _ 0 and a _ 0 ^ * by complex numbers in the hamiltonian, asymptotically yields the right pressure, it also implies the asymptotic equality of | < a _ 0 > | ^ 2 / v and < a _ 0 ^ * a _ 0 > / v in symmetry breaking fields, irrespective of the existence or absence of bose - einstein condensation. because the former was proved by ginibre to hold for absolutely integrable superstable pair interactions, the latter is equally valid in this case. apart from ginibre ' s work, our proof uses only a simple convexity inequality due to griffiths. | arxiv:math-ph/0412056 |
we review curvature - based hyperbolic forms of the evolution part of the cauchy problem of general relativity that we have obtained recently. we emphasize first order symmetrizable hyperbolic systems possessing only physical characteristics. | arxiv:gr-qc/9802027 |
we present a matlab code for exponential integrators method simulating the glioblastoma tumor growth. it employs the fisher - kolmogorov diffusion - reaction tumor brain model with logistic growth. the input is the mri scans of the human head and the initial tumor location. the simulation uses the finite difference formulation in space and the ultra - fast exponential integrators method in time. the output from the code is the input data for paraview visualization. while there are many brain tumor simulation codes, our method ' s novelty lies in its implementation using exponential integrators. we propose a new algorithm for the fast computation of exponential integrators. regarding execution time on a laptop with win10, using matlab, with 11th gen intel ( r ) core ( tm ) i5 - 11500h, 2. 92 ghz, and 32 gb of ram, the algorithm outperforms the state - of - the - art routines from [ a. al - mohy, n. higham, computing the action of the matrix exponential, with an application to exponential integrators. siam journal on scientific computing ( 33 ) 488 - 511 ( 2011 ) ]. we also compare our method with an implicit, unconditionally stable crank - nicolson time integration scheme based on the finite difference method. we show that our method is two orders of magnitude faster than the crank - nicolson method with finite difference discretization in space on a laptop equipped with matlab. the brain tumor two - year future prediction using 128x128x128 computational grid and 100 - time steps, built over the mri scans of the human head, takes less than 10 minutes on the laptop. | arxiv:2402.02273 |
the literature on the price of anarchy ( poa ) of simple auctions employs a no - overbidding assumption but has completely overlooked the no - underbidding phenomenon, which is evident in empirical studies on variants of the second price auction. in this work, we provide a theoretical foundation for the no - underbidding phenomenon. we study the poa of simultaneous 2nd price auctions ( s2pa ) under a new natural condition of { \ em no underbidding }, meaning that agents never bid on items less than their marginal values. we establish improved ( mostly tight ) bounds on the poa of s2pa under no underbidding for different valuation classes ( including unit - demand, submodular, xos, subadditive, and general monotone valuations ), in both full - information and incomplete information settings. to derive our results, we introduce a new parameterized property of auctions, termed $ ( \ gamma, \ delta ) $ - revenue guaranteed, which implies a poa of at least $ \ gamma / ( 1 + \ delta ) $. via extension theorems, this guarantee extends to coarse correlated equilibria ( cce ) in full information settings, and to bayesian poa ( bpoa ) in settings with incomplete information and arbitrary ( correlated ) distributions. we then show that s2pa are $ ( 1, 1 ) $ - revenue guaranteed with respect to bids satisfying no underbidding. this implies a poa of at least $ 1 / 2 $ for general monotone valuation, which extends to bpoa with arbitrary correlated distributions. moreover, we show that $ ( \ lambda, \ mu ) $ - smoothness combined with $ ( \ gamma, \ delta ) $ - revenue guaranteed guarantees a poa of at least $ ( \ gamma + \ lambda ) / ( 1 + \ delta + \ mu ) $. this implies a host of results, such as a tight poa of $ 2 / 3 $ for s2pa with submodular ( or xos ) valuations, under no overbidding and no underbidding. beyond establishing improved bounds for s2pa, the no underbidding assumption sheds new light on the performance of s2pa relative to simultaneous 1st price auctions. | arxiv:2003.11857 |
jamming transition in traffic flow ( between free and jammed traffic ) for homogeneous car following model has been investigated taking into account fluctuations of characteristic acceleration / braking time. these fluctuations are defined by ornstein - uhlenbeck process. the behaviour of the most probable deviation of headway from its optimal value has been studied and phase diagram of the system has been calculated for supercritical and subcritical regimes of jam formation. it has been found that for the first regime the fluctuations of characteristic acceleration / braking time result in coexistence of free moving and jammed traffic, that is typical for the first - order phase transition, and in appearance of two steady states for the second mode. these states correspond to non - zero values of headway deviation at which the formation of jam and congested traffic are possible. using phase - plain portraits method the kinetics of the system transitions has been analyzed for different domains of the phase diagram for both regimes. | arxiv:cond-mat/0204132 |
credit card fraud has emerged as major problem in the electronic payment sector. in this survey, we study data - driven credit card fraud detection particularities and several machine learning methods to address each of its intricate challenges with the goal to identify fraudulent transactions that have been issued illegitimately on behalf of the rightful card owner. in particular, we first characterize a typical credit card detection task : the dataset and its attributes, the metric choice along with some methods to handle such unbalanced datasets. these questions are the entry point of every credit card fraud detection problem. then we focus on dataset shift ( sometimes called concept drift ), which refers to the fact that the underlying distribution generating the dataset evolves over times : for example, card holders may change their buying habits over seasons and fraudsters may adapt their strategies. this phenomenon may hinder the usage of machine learning methods for real world datasets such as credit card transactions datasets. afterwards we highlights different approaches used in order to capture the sequential properties of credit card transactions. these approaches range from feature engineering techniques ( transactions aggregations for example ) to proper sequence modeling methods such as recurrent neural networks ( lstm ) or graphical models ( hidden markov models ). | arxiv:2010.06479 |
millimeter wave ( mmwave ) massive multiple - input multiple - output ( mimo ) has been regarded to be an emerging solution for the next generation of communications, in which hybrid analog and digital precoding is an important method for reducing the hardware complexity and energy consumption associated with mixed signal components. however, the fundamental limitations of the existing hybrid precoding schemes is that they have high computational complexity and fail to fully exploit the spatial information. to overcome these limitations, this paper proposes, a deep - learning - enabled mmwave massive mimo framework for effective hybrid precoding, in which each selection of the precoders for obtaining the optimized decoder is regarded as a mapping relation in the deep neural network ( dnn ). specifically, the hybrid precoder is selected through training based on the dnn for optimizing precoding process of the mmwave massive mimo. additionally, we present extensive simulation results to validate the excellent performance of the proposed scheme. the results exhibit that the dnn - based approach is capable ofminimizing the bit error ratio ( ber ) and enhancing spectrum efficiency of the mmwave massive mimo, which achieves better performance in hybrid precoding compared with conventional schemes while substantially reducing the required computational complexity. | arxiv:1901.06537 |
the global regularity problem for the periodic navier - stokes system asks whether to every smooth divergence - free initial datum $ u _ 0 : ( \ r / \ z ) ^ 3 \ to \ r ^ 3 $ there exists a global smooth solution u. in this note we observe ( using a simple compactness argument ) that this qualitative question is equivalent to the more quantitative assertion that there exists a non - decreasing function $ f : \ r ^ + \ to \ r ^ + $ for which one has a local - in - time \ emph { a priori } bound $ $ \ | u ( t ) \ | _ { h ^ 1 _ x ( ( \ r / \ z ) ^ 3 ) } \ leq f ( \ | u _ 0 \ | _ { h ^ 1 _ x ( ( \ r / \ z ) ^ 3 ) } ) $ $ for all $ 0 < t \ leq 1 $ and all smooth solutions $ u : [ 0, t ] \ times ( \ r / \ z ) ^ 3 \ to \ r ^ 3 $ to the navier - stokes system. we also show that this local - in - time bound is equivalent to the corresponding global - in - time bound. | arxiv:0710.1604 |
we report measurements of the spin susceptibility in dilute ( rs up to 10 ) alas two - dimensional ( 2d ) electrons occupying a single conduction - band valley with an anisotropic in - plane fermi contour, characterized by longitudinal and transverse effective masses, ml and mt. as the density is decreased, the spin susceptibility is significantly enhanced over its band value, reflecting the role of interaction. yet the enhancement is suppressed compared to the results of quantum monte carlo based calculations that take the finite thickness of the electron layer into account but assume an isotropic effective mass equal to sqrt ( ml. mt ). proper treatment of an interacting 2d system with an anisotropic effective mass therefore remains a theoretical challenge. | arxiv:0711.1294 |
an exciton theory for quasi - one dimensional organic materials is developed in the framework of the su - schrieffer - heeger hamiltonian augmented by short range extended hubbard interactions. within a strong electron - electron correlation approximation, the exciton properties are extensively studied. using scattering theory, we analytically obtain the exciton energy and wavefunction and derive a criterion for the existence of a $ b _ u $ exciton. we also systematically investigate the effect of impurities on the coherent motion of an exciton. the coherence is measured by a suitably defined electron - hole correlation function. it is shown that, for impurities with an on - site potential, a crossover behavior will occur if the impurity strength is comparable to the bandwidth of the exciton, corresponding to exciton localization. for a charged impurity with a spatially extended potential, in addition to localization the exciton will dissociate into an uncorrelated electron - hole pair when the impurity is sufficiently strong to overcome the coulomb interaction which binds the electron - hole pair. interchain coupling effects are also discussed by considering two polymer chains coupled through nearest - neighbor interchain hopping $ t _ { \ perp } $ and interchain coulomb interaction $ v _ { \ perp } $. within the $ t $ matrix scattering formalism, for every center - of - mass momentum, we find two poles determined only by $ v _ { \ perp } $, which correspond to the interchain excitons. finally, the exciton state is used to study the charge transfer from a polymer chain to an adjacent dopant molecule. | arxiv:cond-mat/9709254 |
ferroelectricity has been believed unable to coexist with metallicity since the free carriers can screen the internal coulomb interactions of dipoles. very recently, one kind of materials called as ferroelectric metal was reexamined. here, we report the coexistence of metallicity and polar distortion in a new candidate for ferroelectric metal pbti1 - xnbxo3 via doping engineering. the ferroelectric - like polar distortion in all the doped pbti1 - xnbxo3, with x ranging from 0. 04 to 0. 12, was confirmed by the piezoresponse force microscopy and the scanning transmission electron microscopy measurements. pbti1 - xnbxo3 films become more conductive with more doping density, and emerge a metallic behavior when x reaches 0. 12. our first principle calculations further revealed that the doped nb ions in the films can only provide free electrons, but not be able to damage the dipoles in unite cells even with the heaviest doping density of 0. 12 due to their little impact on the off - centering of the ti ions. we believe that these results confirm a feasibility of realizing the coexistence of metallicity and polar distortion for other ferroelectrics in a common way, and motivate the synthesis of some new materials with artificially designed properties even incompatible in nature. | arxiv:1706.04855 |
holographic, virtual reality, autonomous driving, etc. with ten times the speed of 5g, 6g can prove to blend virtual reality within the real world to give an immersive experience. 6g has many applications in almost every industry. internet - connected devices are ubiquitous, and hyper - connectivity like 6g will provide latency - free communication for a robust automation server. = = = smartphone metamorphosis = = = smartphone companies try to blend form and function for optimal value for customers. where some companies have come out with radical designs that totally change the norm of a phone design. like the samsung galaxy fold for example, which was a foldable phone that had a bendable screen. this was a prototype when it debuted but with three iterations and other companies adopting the design. with the new design, the retail price experienced a hike but soon as there will be more competition, prices will follow the market. the flexible screen technology gives opportunities to new design opportunities. the screen size has also played a big role in the smartphone industry as it has allowed companies to pack more tech into the body as well cater towards the high demand for big - screen smartphones. the first popular touchscreen smartphone which was the first iphone apple introduced in 2007 had a screen size of approximately 3. 5 ". that has almost doubled to 6. 7 " for apple ' s lineup of smartphones, while other companies have even crossed the size of 7 ". = = = borderless technology = = = borderless phones lack bezels, allowing the screen to be larger. loading a larger screen into a limited phone size can increase one - handed operability, aesthetics, and a sense of technology. however, the technical problems faced by borderless, light leakage on the screen, accidental touch on the edges, and more fragile bare screens have all been obstacles to the popularization of this technology. = = = transparent phone = = = transparent phone is a mobile phone that uses replaceable glass to achieve a visual penetration effect so that its appearance is transparent. transparent mobile phones use special switchable glass technology. once the electrically controlled glass is activated by a current through a transparent wire, these molecules will rearrange to form text, icons and other images. = = = chip phone = = = the idea is that a cell phone can be made directly at the chip level and implanted in the body. cell phones are used as brain - assisting tools to help improve work efficiency and sensory experience. = = mobile technology classification = = mobile technology | https://en.wikipedia.org/wiki/Mobile_technology |
with the rapid growth in the use of fine - tuning for large language models ( llms ), optimizing fine - tuning while keeping inference efficient has become highly important. however, this is a challenging task as it requires improvements in all aspects, including inference speed, fine - tuning speed, memory consumption, and, most importantly, model quality. previous studies have attempted to achieve this by combining quantization with fine - tuning, but they have failed to enhance all four aspects simultaneously. in this study, we propose a new lightweight technique called quantization for efficient fine - tuning ( qeft ). qeft accelerates both inference and fine - tuning, is supported by robust theoretical foundations, offers high flexibility, and maintains good hardware compatibility. our extensive experiments demonstrate that qeft matches the quality and versatility of full - precision parameter - efficient fine - tuning, while using fewer resources. our code is available at https : / / github. com / xvyaward / qeft. | arxiv:2410.08661 |
we construct a simple thermodynamic model to describe the melting of a supported metal nanoparticle with a spherically curved free surface both with and without surface melting. we use the model to investigate the results of recent molecular dynamics simulations, which suggest the melting temperature of a supported metal particle is the same as that of a free spherical particle with the same surface curvature. our model shows that this is only the case when the contact angles of the supported solid and liquid particles are similar. this is also the case for the temperature at which surface melting begins. | arxiv:0704.0393 |
this is an extension of quantum spinor construction of $ u _ q ( \ hat { \ frak gl } ( n ) ) $. we define quantum affine clifford algebras based on the tensor category and the solutions of q - kz equations, and construct quantum spinor representations of $ u _ q ( \ hat { \ frak o } ( n ) ) $. | arxiv:q-alg/9602021 |
xenon100 is a liquid xenon time projection chamber built to search for rare collisions of hypothetical, weakly interacting massive particles ( wimps ), which are candidates for the dark matter in our universe, with xenon atoms. operated in a low - background shield at the gran sasso underground laboratory in italy, xenon100 has reached the unprecedented background level of < 0. 15 events / ( day kev ) in the energy range below 100 kev in 30 kg of target mass, before electronic / nuclear recoil discrimination. it found no evidence for wimps during a dark matter run lasting for 100. 9 live days in 2010, excluding with 90 % confidence scalar wimp - nucleon cross sections above 7e - 45 cm2 at a wimp mass of 50 gev / c2. a new run started in march 2011, and more than 210 live days of wimp - search data were acquired. results are expected to be released in spring 2012. the construction of the ton - scale xenon1t detector in hall b of the gran sasso laboratory will start in late 2012. | arxiv:1203.1589 |
diffusion - weighted magnetic resonance imaging ( dw - mri ) is a powerful, non - invasive tool for detecting and characterizing abdominal lesions to facilitate early diagnosis, but respiratory motion during a scan reduces image quality and accuracy of quantitative biomarkers. respiratory binning, which groups image slices into motion phase bins based on a navigator signal, can help mitigate motion artifacts. however, in dw - mri, the standard binning technique often generates volumes with missing slices along the superior - inferior axis. thus, longer scans are required to obtain volumes without gaps. in this study, we proposed a new binning technique to minimize missing slices without increasing scan time. we first designed an algorithm using dynamic programming and prefix sum approaches to optimize the initial binning of mr images. then, we developed a probabilistic refinement phase, selecting some slices to belong in two neighboring bins to further reduce missing slices. we tested our two - phase technique on free - breathing abdominal dw - mri scans from eight subjects, including one with tumors. the proposed technique significantly reduced missing slices compared to standard binning ( p < 1. 0 * 10 - 15 ), yielding an average reduction of 81. 74 + / - 7. 58 %. our technique also reduced motion artifacts, improving the conspicuity of malignant lesions. apparent diffusion coefficient ( adc ) maps generated from free - breathing scans corrected using the proposed technique had lower intra - subject variability compared to adc maps from uncorrected free - breathing and shallow - breathing scans ( p < 0. 001 ). additionally, adc maps from shallow - breathing scans were more consistent with corrected free - breathing maps rather than uncorrected free - breathing maps ( p < 0. 01 ). the proposed technique corrects for motion while simultaneously reducing missing slices, allowing for shorter acquisition times compared to standard binning. | arxiv:2409.00798 |
consider a spin manifold m, equipped with a line bundle l and an action of a compact lie group g. we can attach to this data a family theta ( k ) of distributions on the dual of the lie algebra of g. the aim of this paper is to study the asymptotic behaviour of theta ( k ) when k is large, and m possibly non compact, and to explore a functorial consequence of this formula for reduced spaces. | arxiv:1708.08226 |
the finite spectrum of a first - order sentence is the set of positive integers that are the sizes of its models. the class of finite spectra is known to be the same as the complexity class ne. we consider the spectra obtained by limiting models to be either planar ( in the graph - theoretic sense ) or by bounding the degree of elements. we show that the class of such spectra is still surprisingly rich by establishing that significant fragments of ne are included among them. at the same time, we establish non - trivial upper bounds showing that not all sets in ne are obtained as planar or bounded - degree spectra. | arxiv:1609.01789 |
interactions that manifest themselves as lepton number violating processes at low energies in combination with sphaleron transitions typically erase any preexisting baryon asymmetry of the universe. in this article, we discuss the constraints obtained from an observation of neutrinoless double beta decay in this context. if a new physics mechanism of neutrinoless double beta decay other than the standard light neutrino exchange is observed, typical scenarios of high - scale baryogenesis will be excluded unless the baryon asymmetry is stabilized via some new mechanism. we also sketch how this conclusion can be extended beyond the first lepton generation by incorporating lepton flavor violating processes. | arxiv:1503.04825 |
in the analysis of qualification data from the first robotics competition, the ratio of the number of observations to the number of parameters has been found to be quite small for the commonly used winning margin power rating ( wmpr ) model. this usually leads to imprecise estimates and inaccurate predictions in such a three - on - three game. with the finding of a clustering feature in estimated robot strengths, a more flexible model with latent clusters of robots was proposed to alleviate overparameterization of the wmpr model. since its structure can be regarded as a dimension reduction of the parameter space in the wmpr model, the identification of clusters of robot strengths is naturally transformed into a model selection problem. instead of comparing a huge number of competing models, we develop an effective method to estimate the number of clusters, clusters of robots, and robot strengths. the new method consists of two parts : ( i ) a combination of hierarchical and non - hierarchical classifications to determine candidate models ; and ( ii ) variant goodness - of - fit criteria to select optimal models. different from existing hierarchical classification systems, each step of ours is based on estimated robot strengths from a candidate model in the preceding non - hierarchical classification step. a great advantage of the designed non - hierarchical classification system is to examine the possibility of reassigning robots to other cluster sets of robots. to reduce the overestimation of clusters by the mean squared prediction error criteria, the corresponding bic are established as alternatives for model selection. by assembling these essential elements into a coherent whole, a systematic procedure is presented to perform the estimation. in addition, we propose two indices to measure the nested relation between cluster sets of two models and monotonic association between robot strengths of two models. | arxiv:2207.12956 |
we introduce a new class of lower bounds on the log partition function of a markov random field which makes use of a reversed jensen ' s inequality. in particular, our method approximates the intractable distribution using a linear combination of spanning trees with negative weights. this technique is a lower - bound counterpart to the tree - reweighted belief propagation algorithm, which uses a convex combination of spanning trees with positive weights to provide corresponding upper bounds. we develop algorithms to optimize and tighten the lower bounds over the non - convex set of valid parameter values. our algorithm generalizes mean field approaches ( including naive and structured mean field approximations ), which it includes as a limiting case. | arxiv:1203.3494 |
the terahertz spectra of the dynamic conductivity and radiation absorption coefficient in germanium - silicon heterostructures with arrays of ge hut clusters ( quantum dots ) have been measured for the first time in the frequency range of 0. 3 - 1. 2 thz at room temperature. it has been found that the effective dynamic conductivity and effective radiation absorption coefficient in the heterostructure due to the presence of germanium quantum dots in it are much larger than the respective quantities of both the bulk ge single crystal and ge / si ( 001 ) without arrays of quantum dots. the possible microscopic mechanisms of the detected increase in the absorption in arrays of quantum dots have been discussed. | arxiv:1101.3527 |
interfaces based on projection screens have become increasingly more popular in recent years, mainly due to the large screen size and resolution that they provide, as well as their stereo - vision capabilities. this work shows a local method for real - time detection of non - stationary photometric perturbations in projected images by means of computer vision techniques. the method is based on the computation of differences between the images in the projector ' s frame buffer and the corresponding images on the projection screen observed by the camera. it is robust under spatial variations in the intensity of light emitted by the projector on the projection surface and also robust under stationary photometric perturbations caused by external factors. moreover, we describe the experiments carried out to show the reliability of the method. | arxiv:1411.6275 |
this study presents a finite element analysis approach to non - linear and linearized tensegrity dynamics based on the lagrangian method with nodal coordinate vectors as the generalized coordinates. in this paper, nonlinear tensegrity dynamics with and without constraints are first derived. the equilibrium equations in three standard forms ( in terms of nodal coordinate, force density, and force vectors ) and the compatibility equation are also given. then, we present the linearized dynamics and modal analysis equations with and without constraints. the developed approach is capable of conducting the following comprehensive dynamics studies for any tensegrity structures accurately : 1. performing rigid body dynamics with acceptable errors, which is achieved by setting relatively high stiffness for bars in the simulation. 2. simulating fem dynamics accurately, where bars and strings can have elastic or plastic deformations. 3. dealing with various kinds of boundary conditions, for example, fixing or applying static / dynamic loads at any nodes in any direction ( i. e., gravitational force, some specified forces, or arbitrary seismic vibrations ). 4. conducting accurate modal analysis, including natural frequency and corresponding modes. three examples, a double pendulum, a cantilever truss with external force, and a double prism tensegrity tower, are carefully selected and studied. the results are compared with rigid body dynamics and fem software ansys. this study provides a deep insight into structures, materials, performances, as well as an interface towards integrating control theories. | arxiv:2106.02176 |
process - based confidential computing enclaves such as intel sgx can be used to protect the confidentiality and integrity of workloads, without the overhead of virtualisation. however, they introduce a notable performance overhead, especially when it comes to transitions in and out of the enclave context. such overhead makes the use of enclaves impractical for running io - intensive applications, such as network packet processing or biological sequence analysis. we build on earlier approaches to improve the io performance of work - loads in intel sgx enclaves and propose the sgx - bundler library, which helps reduce the cost of both individual single enclave transitions well as of the total number of enclave transitions in trusted applications running in intel sgx enclaves. we describe the implementation of the sgx - bundler library, evaluate its performance and demonstrate its practicality using the case study of open vswitch, a widely used software switch implementation. | arxiv:2112.07339 |
we explore the holographic properties of non - perturbative vacuum decay in anti - de sitter ( $ \ mathrm { ads } $ ) geometries. to this end, we consider a gravitational theory in a metastable $ \ mathrm { ads } _ 3 $ state, which decays into an $ \ mathrm { ads } _ 3 $ of lower vacuum energy via bubble nucleation, and we employ the ryu - takayanagi conjecture to compute the entanglement entropy $ s _ \ text { ent } $ in its alleged holographic dual. our analysis leads us to infer that the nucleation and growth of a vacuum bubble correspond, in the boundary theory, to the introduction of a relevant deformation and a subsequent renormalization group ( rg ) flow, where $ s _ \ text { ent } $ provides a $ c $ - function. we provide further evidence for the claim and comment on the holographic interpretation of off - centred or multiple bubbles. we also frame the issue in the formalism of holographic integral geometry, discussing the consequences on the structure of the holographic rg flow and recovering the standard holographic rg as a limiting case. | arxiv:1806.02289 |
the auger engineering radio array ( aera ) aims at the detection of air showers induced by high - energy cosmic rays. as an extension of the pierre auger observatory, it measures complementary information to the particle detectors, fluorescence telescopes and to the muon scintillators of the auger muons and infill for the ground array ( amiga ). aera is sensitive to all fundamental parameters of an extensive air shower such as the arrival direction, energy and depth of shower maximum. since the radio emission is induced purely by the electromagnetic component of the shower, in combination with the amiga muon counters, aera is perfect for separate measurements of the electrons and muons in the shower, if combined with a muon counting detector like amiga. in addition to the depth of the shower maximum, the ratio of the electron and muon number serves as a measure of the primary particle mass. | arxiv:1704.07240 |
deep learning analyses have offered sensitivity leaps in detection of cognitive states from functional mri ( fmri ) measurements across the brain. yet, as deep models perform hierarchical nonlinear transformations on their input, interpreting the association between brain responses and cognitive states is challenging. among common explanation approaches for deep fmri classifiers, attribution methods show poor specificity and perturbation methods show limited plausibility. while counterfactual generation promises to address these limitations, previous methods use variational or adversarial priors that yield suboptimal sample fidelity. here, we introduce the first diffusion - driven counterfactual method, dreamr, to enable fmri interpretation with high specificity, plausibility and fidelity. dreamr performs diffusion - based resampling of an input fmri sample to alter the decision of a downstream classifier, and then computes the minimal difference between the original and counterfactual samples for explanation. unlike conventional diffusion methods, dreamr leverages a novel fractional multi - phase - distilled diffusion prior to improve sampling efficiency without compromising fidelity, and it employs a transformer architecture to account for long - range spatiotemporal context in fmri scans. comprehensive experiments on neuroimaging datasets demonstrate the superior specificity, fidelity and efficiency of dreamr in sample generation over state - of - the - art counterfactual methods for fmri interpretation. | arxiv:2307.09547 |
in this paper, we establish a second main theorem for holomorphic maps with finite growth index on complex discs intersecting arbitrary families of hypersurfaces ( fixed and moving ) in projective varieties, which gives an above bound of the sum of truncated defects. our result also is generalizes and improves many previous second main theorems for holomorphic maps from $ \ mathbb c $ intersecting hypersurfaces ( moving and fixed ) in projective varieties. | arxiv:2404.18111 |
batch normalization is a key component of most image classification models, but it has many undesirable properties stemming from its dependence on the batch size and interactions between examples. although recent work has succeeded in training deep resnets without normalization layers, these models do not match the test accuracies of the best batch - normalized networks, and are often unstable for large learning rates or strong data augmentations. in this work, we develop an adaptive gradient clipping technique which overcomes these instabilities, and design a significantly improved class of normalizer - free resnets. our smaller models match the test accuracy of an efficientnet - b7 on imagenet while being up to 8. 7x faster to train, and our largest models attain a new state - of - the - art top - 1 accuracy of 86. 5 %. in addition, normalizer - free models attain significantly better performance than their batch - normalized counterparts when finetuning on imagenet after large - scale pre - training on a dataset of 300 million labeled images, with our best models obtaining an accuracy of 89. 2 %. our code is available at https : / / github. com / deepmind / deepmind - research / tree / master / nfnets | arxiv:2102.06171 |
we present here the results of the first part of the vlbi ecliptic plane survey ( veps ) program. the goal of the program is to find all compact sources within $ 7. 5 ^ \ circ $ of the ecliptic plane which are suitable as calibrators for anticipated phase referencing observations of spacecraft and determine their positions with accuracy at the 1. 5 ~ nrad level. we run the program in two modes : the search mode and the refining mode. in the search mode, a complete sample of all sources brighter than 50 mjy at 5 ghz listed in the parkes - mit - nrao ( pmn ) and green bank 6 ~ cm ( gb6 ) catalogs, except those previously detected with vlbi, is observed. in the refining mode, the positions of all ecliptic plane sources, including those found in the search mode, are improved. by october 2016, thirteen 24 - hr sessions that targeted all sources brighter than 100 ~ mjy have been observed and analyzed. among 3320 observed target sources, 555 objects have been detected. we also conducted a number of follow - up vlbi experiments in the refining mode and improved the positions of 249 ecliptic plane sources. | arxiv:1701.07287 |
we explore the application of computer vision and machine learning ( ml ) techniques to predict material properties ( e. g. compressive strength ) based on sem images. we show that it ' s possible to train ml models to predict materials performance based on sem images alone, demonstrating this capability on the real - world problem of predicting uniaxially compressed peak stress of consolidated molecular solids samples. our image - based ml approach reduces mean absolute percent error ( mape ) by an average of 24 % over baselines representative of the current state - of - the - practice ( i. e., domain - expert ' s analysis and correlation ). we compared two complementary approaches to this problem : ( 1 ) a traditional ml approach, random forest ( rf ), using state - of - the - art computer vision features and ( 2 ) an end - to - end deep learning ( dl ) approach, where features are learned automatically from raw images. we demonstrate the complementarity of these approaches, showing that rf performs best in the " small data " regime in which many real - world scientific applications reside ( up to 24 % lower rmse than dl ), whereas dl outpaces rf in the " big data " regime, where abundant training samples are available ( up to 24 % lower rmse than rf ). finally, we demonstrate that models trained using machine learning techniques are capable of discovering and utilizing informative crystal attributes previously underutilized by domain experts. | arxiv:1906.02130 |
based on an empirical analysis of author usage of corr, and of its predecessor in the los alamos eprint archives, it is shown that corr has not yet been able to match the early growth of the los alamos physics archives. some of the reasons are implicit in halpern ' s paper, and we explore them further here. in particular we refer to the need to promote corr more effectively for its intended community - computer scientists in universities, industrial research labs and in government. we take up some points of detail on this new world of open archiving concerning central versus distributed self - archiving, publication, the restructuring of the journal publishers ' niche, peer review and copyright. | arxiv:cs/0009004 |
here we present the results of various approaches to measure accurate colours and photometric redshifts ( photo - z ' s ) from wide - field imaging data. we use data from the canada - france - hawaii - telescope legacy survey ( cfhtls ) which have been re - processed by the cfht lensing survey ( cfhtlens ) team in order to carry out a number of weak gravitational lensing studies. an emphasis is put on the correction of systematic effects in the photo - z ' s arising from the different point spread functions ( psf ) in the five optical bands. different ways of correcting these effects are discussed and the resulting photo - z accuracies are quantified by comparing the photo - z ' s to large spectroscopic redshift ( spec - z ) data sets. careful homogenisation of the psf between bands leads to increased overall accuracy of photo - z ' s. the gain is particularly pronounced at fainter magnitudes where galaxies are smaller and flux measurements are affected more by psf - effects. we also study possible re - calibrations of the photometric zeropoints ( zps ) with the help of galaxies with known spec - z ' s. we find that if psf - effects are properly taken into account, a re - calibration of the zps becomes much less important suggesting that previous such re - calibrations described in the literature could in fact be mostly corrections for psf - effects rather than corrections for real inaccuracies in the zps. the implications of this finding for future surveys like kids, des, lsst, or euclid are mixed. on the one hand, zp re - calibrations with spec - z ' s might not be as accurate as previously thought. on the other hand, careful psf homogenisation might provide a way out and yield accurate, homogeneous photometry without the need for full spectroscopic coverage. this is the first paper in a series describing the technical aspects of cfhtlens. ( abridged ) | arxiv:1111.4434 |
we propose an algorithm for approximative dictionary lookup, where altered strings are matched against reference forms. the algorithm makes use of a divergence function between strings - - broadly belonging to the family of edit distances ; it finds dictionary entries whose distance to the search string is below a certain threshold. the divergence function is not the classical edit distance ( dl distance ) ; it is adaptable to a particular corpus, and is based on elementary alteration costs defined on character blocks, rather than on individual characters. nous proposons un algorithme de recherche approximative de cha \ ^ ines dans un dictionnaire \ ` a partir de formes alt \ ' er \ ' ees. cet algorithme est fond \ ' e sur une fonction de divergence entre cha \ ^ ines ~ - - une sorte de distance d ' \ ' edition : il recherche des entr \ ' ees pour lesquelles la distance \ ` a la cha \ ^ ine cherch \ ' ee est inf \ ' erieure \ ` a un certain seuil. la fonction utilis \ ' ee n ' est pas la distance d ' \ ' edition classique ( distance dl ) ; elle est adapt \ ' ee \ ` a un corpus, et se fonde sur la prise en compte de co \ ^ uts d ' alt \ ' eration \ ' el \ ' ementaires d \ ' efinis non pas sur des caract \ ` eres, mais sur des sous - cha \ ^ ines ( des blocs de caract \ ` eres ). | arxiv:2109.00624 |
the formation and evolution of low - mass stars within dense halos of dark matter ( dm ) leads to evolution scenarios quite different from the classical stellar evolution. as a result of our detailed numerical work, we describe these new scenarios for a range of dm densities on the host halo, a range of scattering cross sections of the dm particles considered, and for stellar masses from 0. 7 to 3 m _ { \ odot }. for the first time, we also computed the evolution of young low - mass stars in their hayashi track in the pre - main sequence phase and found that, for high dm densities, these stars stop their gravitational collapse before reaching the main sequence, in agreement with similar studies on first stars. such stars remain indefinitely in an equilibrium state with lower effective temperatures ( | \ delta t _ eff | > 10 ^ 3 k for a star of one solar mass ), the annihilation of captured dm particles in their core being the only source of energy. in the case of lower dm densities, these proto - stars continue their collapse and progress through the main sequence burning hydrogen at a lower rate. a star of 1 m _ { \ odot } will spend a time greater than the current age of the universe consuming all the hydrogen in its core if it evolves in a halo with dm density \ rho _ { \ chi } = 10 ^ 9 gev cm ^ - 3. we also show the strong dependence of the effective temperature and luminosity of these stars on the characteristics of the dm particles and how this can be used as an alternative method for dm research. | arxiv:0909.1971 |
this paper introduces actgan - a novel end - to - end generative adversarial network ( gan ) for one - shot face reenactment. given two images, the goal is to transfer the facial expression of the source actor onto a target person in a photo - realistic fashion. while existing methods require target identity to be predefined, we address this problem by introducing a " many - to - many " approach, which allows arbitrary persons both for source and target without additional retraining. to this end, we employ the feature pyramid network ( fpn ) as a core generator building block - the first application of fpn in face reenactment, producing finer results. we also introduce a solution to preserve a person ' s identity between synthesized and target person by adopting the state - of - the - art approach in deep face recognition domain. the architecture readily supports reenactment in different scenarios : " many - to - many ", " one - to - one ", " one - to - another " in terms of expression accuracy, identity preservation, and overall image quality. we demonstrate that actgan achieves competitive performance against recent works concerning visual quality. | arxiv:2003.13840 |
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