cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Critical behavior of the quasi-periodic quantum Ising chain
Creators: name: Crowley, P. J. D.
name: Laumann, C. R.
name: Chandran, A.
Publisher: name: arXiv
Year: 2018
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: The interplay of correlated spatial modulation and symmetry breaking leads to quantum critical phenomena intermediate between those of the clean and randomly disordered cases. By performing a detailed analytic and numerical case study of the quasi-periodically (QP) modulated transverse field Ising chain, we provide evidence for the conjectures of Ref. [Crowley et. al. 2018] regarding the QP-Ising universality class. In the generic case, we confirm that the logarithmic wandering coefficient $w$ governs both the macroscopic critical exponents and the energy-dependent localisation length of the critical excitations. However, for special values of the phase difference $Δ$ between the exchange and transverse field couplings, the QP-Ising transition has different properties. For $Δ=0$, a generalised Aubry-André duality prevents the finite energy excitations from localising despite the presence of logarithmic wandering. For $Δ$ such that the fields and couplings are related by a lattice shift, the wandering coefficient $w$ vanishes. Nonetheless, the presence of small couplings leads to non-trivial exponents and localised excitations. Our results add to the rich menagerie of quantum Ising transitions in the presence of spatial modulation.
description: 22 Pages 13 Figures
Review of guidelines on expression, storage and transport of breast milk for infants in hospital, to guide formulation of such recommendations in Sri Lanka
Creators: name: Rodrigo, Ranmali
name: Amir, Lisa
name: Forster, Della
Publisher: name: La Trobe
Year: 2023
Subjects: classificationCode: 4204
subject: Midwifery
classificationCode: 3213
subject: Paediatrics

description: Background: Sick newborns in neonatal units who are unable to breastfeed are fed expressed breast milk. In Sri Lanka, most mothers stay in hospital throughout baby's stay to provide this milk freshly. In other countries mothers go home, express breast milk at home and bring it to hospital. There are concerns about the safety of transported expressed milk if used in a tropical middle-income country. The aim of this paper is to compare and contrast advice offered by different hospitals and organizations on how to express, store and transport breast milk safely. Methods: We assessed guidelines used by hospital staff of the four Level 3 neonatal units in Melbourne, Australia, National Health Service UK, guidelines and training manuals of the Human Milk Banking Association of North America, the World Health Organization and an information leaflet from Family Health Bureau, Sri Lanka. Information on breast milk expression, storage and transport provided by the guidelines were tabulated under seven topics: general information; container for milk collection; hand expression; using a pump for expression; storage; thawing / warming; and transport of expressed breast milk. The AGREE II tool was used to assess the guidelines written for hospital staff. Results: There was considerable agreement on most recommendations provided by these sources, but no single source covered all topics in full. Most recommend hand expression as the initial method for expressing of breast milk, followed by breast pump use, except the Sri Lankan recommendations which strongly discourages the use of breast pumps. Durations of storage under various conditions are generally similar in the different recommendations. Most guidelines recommend a 'cool box' or container with ice or freezer packs for transportation of milk. Conclusion: A single document containing recommendations on all aspects of expressing, storing and transporting breast milk should be available for each unit, with the same basic information for mothers and the healthcare staff and further technical details for staff if required. The Sri Lankan recommendations need to be updated based on current worldwide practices and further studies are needed to establish a safe method of transport of expressed breast milk in Sri Lanka.
Laws of the iterated logarithm on covering graphs with groups of polynomial volume growth
Creators: name: Namba, Ryuya
Publisher: name: arXiv
Year: 2019
Subjects: subject: Probability (math.PR)
subject: FOS: Mathematics
subject: 60F10, 60F15, 60J10

description: Moderate deviation principles (MDPs) for random walks on covering graphs with groups of polynomial volume growth are discussed in a geometric point of view. They deal with any intermediate spatial scalings between those of laws of large numbers and those of central limit theorems. The corresponding rate functions are given by quadratic forms determined by the Albanese metric associated with the given random walks. We apply MDPs to establish laws of the iterated logarithm on the covering graphs by characterizing the set of all limit points of the normalized random walks.
description: 21 pages
Surface Crouzeix-Raviart element for the Laplace-Beltrami equation
Creators: name: Guo, Hailong
Publisher: name: arXiv
Year: 2018
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics

description: This paper is concerned with the nonconforming finite element discretization of geometric partial differential equations. In specific, we construct a surface Crouzeix-Raviart element on the linear approximated surface, analogous to a flat surface. The optimal error estimations are established even though the presentation of the geometric error. By taking the intrinsic viewpoint of manifolds, we introduce a new superconvergent gradient recovery method for the surface Crouzeix-Raviart element using only the information of discretization surface. The potential of serving as an asymptotically exact {\it a posteriori} error estimator is also exploited. A series of benchmark numerical examples are presented to validate the theoretical results and numerically demonstrate the superconvergence of the gradient recovery method.
On the topology of moduli spaces of non-negatively curved Riemannian metrics
Creators: name: Tuschmann, Wilderich
name: Wiemeler, Michael
Publisher: name: arXiv
Year: 2017
Subjects: subject: Differential Geometry (math.DG)
subject: Geometric Topology (math.GT)
subject: FOS: Mathematics

description: We study spaces and moduli spaces of Riemannian metrics with non-negative Ricci or non-negative sectional curvature on closed and open manifolds. We construct, in particular, the first classes of manifolds for which these moduli spaces have non-trivial rational homotopy, homology and cohomology groups. We also show that in every dimension at least seven (respectively, at least eight) there exist closed (respectively, open) manifolds for which the space and moduli space of Riemannian metrics with non-negative sectional curvature has infinitely many path components. A completely analogous statement holds for spaces and moduli spaces of non-negative Ricci curvature metrics.
description: 26 pages; minor changes; accepted for publication in Math. Ann
Non-negatively curved GKM orbifolds
Creators: name: Goertsches, Oliver
name: Wiemeler, Michael
Publisher: name: arXiv
Year: 2018
Subjects: subject: Differential Geometry (math.DG)
subject: Geometric Topology (math.GT)
subject: FOS: Mathematics

description: In this paper we study non-negatively curved and rationally elliptic GKM$_4$ manifolds and orbifolds. We show that their rational cohomology rings are isomorphic to the rational cohomology of certain model orbifolds. These models are quotients of isometric actions of finite groups on non-negatively curved torus orbifolds. Moreover, we give a simplified proof of a characterisation of products of simplices among orbit spaces of locally standard torus manifolds. This characterisation was originally proved in [Wiemeler, Torus manifolds and non-negative curvature, arXiv:1401.0403] and was used there to obtain a classification of non-negatively curved torus manifolds.
description: 35 pages; 7 figures; minor changes in v4; to appear in Math. Z
Fractional charge bound to a vortex in two dimensional topological crystalline insulators
Creators: name: Lee, Eunwoo
name: Furusaki, Akira
name: Yang, Bohm-Jung
Publisher: name: arXiv
Year: 2019
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We establish the correspondence between the fractional charge bound to a vortex in a textured lattice and the relevant bulk band topology in two-dimensional (2D) topological crystalline insulators. As a representative example, we consider the Kekule textured graphene whose bulk band topology is characterized by a 2D $\mathbb{Z}_{2}$ topological invariant $ν_{\rm 2D}$ protected by inversion symmetry. The fractional charge localized at a vortex in the Kekule texture is shown to be related to the change in the bulk topological invariant $ν_{\rm 2D}$ around the vortex, as in the case of the Su-Schriefer-Heeger model in which the fractional charge localized at a domain wall is related to the change in the bulk charge polarization between degenerate ground states. We show that the effective three-dimensional (3D) Hamiltonian, where the angle $θ$ around a vortex in Kekule-textured graphene is a third coordinate, describes a 3D axion insulator with a quantized magnetoelectric polarization. The spectral flow during the adiabatic variation of $θ$ corresponds to the chiral hinge modes of an axion insulator and determines the accumulated charge localized at the vortex, which is half-quantized when chiral symmetry exists. When chiral symmetry is absent, electric charge localized at the vortex is no longer quantized, but the vortex always carries a half-quantized Wannier charge as long as inversion symmetry exists. For the cases when magnetoelectric polarization is quantized due to the presence of symmetry that reverses the space-time orientation, we classify all possible topological crystalline insulators whose vortex defect carries a fractional charge.
description: 5+8 pages, 3+6 figures, 1+1 tables
A Simple proof of Johnson-Lindenstrauss extension theorem
Creators: name: Mendel, Manor
Publisher: name: arXiv
Year: 2018
Subjects: subject: Metric Geometry (math.MG)
subject: Functional Analysis (math.FA)
subject: FOS: Mathematics
subject: 46T20, 51F99, 54C20

description: Johnson and Lindenstrauss proved that any Lipschitz mapping from an $n$-point subset of a metric space into Hilbert space can be extended to the whole space, while increasing the Lipschitz constant by a factor of $O(\sqrt{\log n})$. We present a simplification of their argument that avoids dimension reduction and the Kirszbraun theorem.
description: 3 pages. Incorporation of reviewers' suggestions
Boundary maps and maximal representations on infinite dimensional Hermitian symmetric spaces
Creators: name: Duchesne, Bruno
name: Lécureux, Jean
name: Pozzetti, Maria Beatrice
Publisher: name: arXiv
Year: 2018
Subjects: subject: Group Theory (math.GR)
subject: Differential Geometry (math.DG)
subject: FOS: Mathematics
subject: 20F67, 32M15

description: We define a Toledo number for actions of surface groups and complex hyperbolic lattices on infinite dimensional Hermitian symmetric spaces, which allows us to define maximal representations. When the target is not of tube type we show that there cannot be Zariski-dense maximal representations, and whenever the existence of a boundary map can be guaranteed, the representation preserves a finite dimensional totally geodesic subspace on which the action is maximal. In the opposite direction we construct examples of geometrically dense maximal representation in the infinite dimensional Hermitian symmetric space of tube type and finite rank. Our approach is based on the study of boundary maps, that we are able to construct in low ranks or under some suitable Zariski-density assumption, circumventing the lack of local compactness in the infinite dimensional setting.
description: Final version. To appear in ETDS
Analysing the 21cm signal from the Epoch of Reionization with artificial neural networks
Creators: name: Shimabukuro, Hayato
name: Semelin, Benoit
Publisher: name: arXiv
Year: 2017
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: The 21 cm signal from the Epoch of Reionization should be observed within the next decade. While a simple statistical detection is expected with SKA pathfinders, the SKA will hopefully produce a full 3D mapping of the signal. To extract from the observed data constraints on the parameters describing the underlying astrophysical processes, inversion methods must be developed. For example, the Markov Chain Monte Carlo method has been successfully applied. Here we test another possible inversion method: artificial neural networks (ANN). We produce a training set which consists of 70 individual sample. Each sample is made of the 21 cm power spectrum at different redshifts produced with the 21cmFast code plus the value of three parameters used in the semi-numerical simulations that describe astrophysical processes. Using this set we train the network to minimize the error between the parameter values it produces as an output and the true values. We explore the impact of the architecture of the network on the quality of the training. Then we test the trained network on the new set of 54 test samples with different values of the parameters. We find that the quality of the parameter reconstruction depends on the sensitivity of the power spectrum to the different parameters at a given redshift, that including thermal noise and sample variance decreases the quality of the reconstruction and that using the power spectrum at several redshifts as an input to the ANN improves the quality of the reconstruction. We conclude that ANNs are a viable inversion method whose main strength is that they require a sparse exploration of the parameter space and thus should be usable with full numerical simulations.
description: 8 figures, 2 tables, accepted in MNRAS
Standard Model Effective Field Theory from On-shell Amplitudes
Creators: name: Ma, Teng
name: Shu, Jing
name: Xiao, Ming-Lei
Publisher: name: arXiv
Year: 2019
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We present a general method of constructing unfactorizable on-shell amplitudes (amplitude basis), and build up their one-to-one correspondence to the independent and complete operator basis in effective field theory (EFT). We apply our method to the Standard Model EFT, and identify the amplitude basis in dimension 5 and 6, which correspond to the Weinberg operator and operators in Warsaw basis except for some linear combinations.
description: 9 pages, 1 figure, 3 appendices
Lack of thermal energy in superbubbles: hint of cosmic rays?
Creators: name: Gupta, Siddhartha
name: Nath, Biman B.
name: Sharma, Prateek
name: Eichler, David
Publisher: name: arXiv
Year: 2017
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Using analytic methods and $1$-D two-fluid simulations, we study the effect of cosmic rays (CRs) on the dynamics of interstellar superbubbles (ISBs) driven by multiple supernovae (SNe)/stellar winds in OB associations. In addition to CR advection and diffusion, our models include thermal conduction and radiative cooling. We find that CR injection at the reverse shock or within a central wind-driving region can affect the thermal profiles of ISBs and hence their X-ray properties. Even if a small fraction ($10-20\%$) of the total mechanical power is injected into CRs, a significant fraction of the ram pressure at the reverse shock can be transferred to CRs. The energy transfer becomes efficient if (1) the reverse shock gas Mach number exceeds a critical value ($M_{\rm th}\gtrsim 12$) and (2) the CR acceleration time scale $τ_{\rm acc}\sim κ_{\rm cr}/v^2$ is shorter than the dynamical time, where $κ_{\rm cr}$ is CR diffusion constant and $v$ is the upstream velocity. We show that CR affected bubbles can exhibit a volume averaged hot gas temperature $1-5\times10^{6}$ K, lower by a factor of $2-10$ than without CRs. Thus CRs can potentially solve the long-standing problem of the observed low ISB temperatures.
description: 18 pages, 18 figures, 3 tables; submitted to MNRAS; Comments welcome
Pancreas segmentation with probabilistic map guided bi-directional recurrent UNet
Creators: name: Li, Jun
name: Lin, Xiaozhu
name: Che, Hui
name: Li, Hao
name: Qian, Xiaohua
Publisher: name: arXiv
Year: 2019
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: Pancreas segmentation in medical imaging data is of great significance for clinical pancreas diagnostics and treatment. However, the large population variations in the pancreas shape and volume cause enormous segmentation difficulties, even for state-of-the-art algorithms utilizing fully-convolutional neural networks (FCNs). Specifically, pancreas segmentation suffers from the loss of spatial information in 2D methods, and the high computational cost of 3D methods. To alleviate these problems, we propose a probabilistic-map-guided bi-directional recurrent UNet (PBR-UNet) architecture, which fuses intra-slice information and inter-slice probabilistic maps into a local 3D hybrid regularization scheme, which is followed by bi-directional recurrent network optimization. The PBR-UNet method consists of an initial estimation module for efficiently extracting pixel-level probabilistic maps and a primary segmentation module for propagating hybrid information through a 2.5D U-Net architecture. Specifically, local 3D information is inferred by combining an input image with the probabilistic maps of the adjacent slices into multichannel hybrid data, and then hierarchically aggregating the hybrid information of the entire segmentation network. Besides, a bi-directional recurrent optimization mechanism is developed to update the hybrid information in both the forward and the backward directions. This allows the proposed network to make full and optimal use of the local context information. Quantitative and qualitative evaluation was performed on the NIH Pancreas-CT dataset, and our proposed PBR-UNet method achieved better segmentation results with less computational cost compared to other state-of-the-art methods.
description: accepted by Physics in Medicine & Biology
An instrument for advanced in situ x-ray studies of metal-organic vapor phase epitaxy of III-nitrides
Creators: name: Ju, Guangxu
name: Highland, Matthew J.
name: Yanguas-Gil, Angel
name: Thompson, Carol
name: Eastman, Jeffrey A.
name: Zhou, Hua
name: Brennan, Sean M.
name: Stephenson, G. Brian
name: Fuoss, Paul H.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Instrumentation and Detectors (physics.ins-det)
subject: FOS: Physical sciences

description: We describe an instrument that exploits the ongoing revolution in synchrotron sources, optics, and detectors to enable in situ studies of metal-organic vapor phase epitaxy (MOVPE) growth of III-nitride materials using coherent x-ray methods. The system includes high-resolution positioning of the sample and detector including full rotations, an x-ray transparent chamber wall for incident and diffracted beam access over a wide angular range, and minimal thermal sample motion, giving the sub-micron positional stability and reproducibility needed for coherent x-ray studies. The instrument enables surface x-ray photon correlation spectroscopy, microbeam diffraction, and coherent diffraction imaging of atomic-scale surface and film structure and dynamics during growth, to provide fundamental understanding of MOVPE processes.
description: 13 pages, 13 figures, published in RSI v2 revision, clarified several points for reader from suggestions of referees, fixed typo Please cite paper as : G. Ju, et al., Review of Scientific Instruments 88, 035113 (2017)
Oscillating Shells and Oscillating Balls in AdS
Creators: name: Banerjee, Avik
name: Kundu, Arnab
name: Roy, Pratik
name: Virmani, Amitabh
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: It has recently been reported that certain thin timelike shells undergo oscillatory motion in AdS. In this paper, we compute two-point function of a probe field in the geodesic approximation in such an oscillating shell background. We confirm that the two-point function exhibits an oscillatory behaviour following the motion of the shell. We show that similar oscillatory dynamics is possible when the perfect fluid on the shell has a polytropic equation of state. Moreover, we show that certain ball like configurations in AdS also exhibit oscillatory motion and comment on how such a solution can be smoothly matched to an appropriate exterior solution. We also demonstrate that the weak energy condition is satisfied for these oscillatory configurations.
description: 23 pages, 5 figures; v2: refs added; v3: JHEP version
AGN-Host Connection at 0.5 < z < 2.5: A rapid evolution of AGN fraction in red galaxies during the last 10 Gyr
Creators: name: Wang, Tao
name: Elbaz, D.
name: Alexander, D. M.
name: Xue, Y. Q.
name: Gabor, J. M.
name: Juneau, S.
name: Schreiber, C.
name: Zheng, X-Z.
name: Wuyts, S.
name: Shi, Y.
name: Daddi, E.
name: Shu, X-W.
name: Fang, G-W.
name: Huang, J-S.
name: Luo, B.
name: Gu, Q-S.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We explore the dependence of the incidence of moderate-luminosity ($L_{X} = 10^{41.9-43.7}$ erg s$^{-1}$) AGNs and the distribution of their accretion rates on host color at 0.5 < z < 2.5, using deep X-ray data in GOODS fields. We use extinction-corrected rest-frame U-V colors to divide both AGN hosts and non-AGN galaxies into red sequence (quiescent), green valley (transition), and blue cloud (star-forming) populations. We find that both the AGN fraction at fixed stellar mass and its evolution with redshift are dependent on host colors. Most notably, red galaxies have the lowest AGN fraction (~5\%) at z~1 yet with most rapid redshift evolution, increasing by a factor of 5 (~24\%) at z~2. Green galaxies exhibit the highest AGN fraction across all redshifts, which is most pronounced at z~2 with more than half of them hosting an AGN at $M_{*} > 10^{10.6} M_{\odot}$. Together with the high AGN fraction in red galaxies at z~2, this indicates that X-ray AGNs could be important in both transforming blue galaxies into red ones and subsequently maintaining their quiescence at high redshift. Furthermore, consistent with low-redshift studies, we find that the probability of hosting an AGN in the total galaxy population can be characterized by a universal Eddington ratio ($p(λ_{Edd}) \sim λ_{Edd}^{-0.4}$) and a moderate redshift evolution. Yet consistent with their different AGN fractions, different populations appear to also have different $p(λ_{Edd})$ with red galaxies exhibiting more rapid redshift evolution than green and blue ones. Evidence for a steeper power law of $p(λ_{Edd})$ in red galaxies is also presented, though larger samples are needed to confirm. These results suggest that the AGN accretion or the growth of supermassive black holes is related to their host properties, and may also influence their hosts in a different mode dependent on the host color.
description: A&A, in press
Unraveling linguistic patterns in dog behaviour
Creators: name: Banerjee, Arunita
name: Das, Nandan
name: Dey, Rajib
name: Majumder, Shouvik
name: Shit, Piuli
name: Banerjee, Ayan
name: Ghosh, Nirmalya
name: Bhadra, Anindita
Publisher: name: arXiv
Year: 2019
Subjects: subject: Physics and Society (physics.soc-ph)
subject: FOS: Physical sciences

description: Apparently random events in nature often reveal hidden patterns when analysed using diverse and robust statistical tools. Power-law distributions, for example, project diverse natural phenomenon, ranging from earthquakes1 to heartbeat dynamics2 onto a common platform of statistical self-similarity. A large range of human languages are known to follow a specific regime of power-law distributions, the Zipf-Mandelbrot law, in addition to showing properties like the Pareto principle and Shannon entropy3,4. Animal behaviour in specific contexts have been shown to follow power-law distributions5,6. However, the entire behavioural repertoire of a species has never been analysed for the existence of underlying patterns. Here we show that the frequency-rank data of randomly sighted behaviours at the population level of free-ranging dogs follow a scale-invariant power-law behaviour. While the data does not display Zipfian trends, it obeys the Pareto principle and Shannon entropy rules akin to languages. Interestingly, the data also exhibits robust self-similarity patterns at different scales which we extract using multifractal detrended fluctuation analysis7. The observed multifractal trends suggest that the probability of consecutive occurrence of behaviours of adjacent ranks is much higher than behaviours widely separated in rank. Since we observe such robust trends in random data sets, we hypothesize that the general behavioural repertoire of a species is shaped by a syntax similar to languages. This opens up the prospect of future multifractal and other statistical investigations on true time series of behavioural data to probe the existence of possible long and short-range correlations, and thereby develop predictive models of behaviour.
description: 2 figures, 4 pages supplementary information
The finiteness conjecture for skein modules
Creators: name: Gunningham, Sam
name: Jordan, David
name: Safronov, Pavel
Publisher: name: arXiv
Year: 2019
Subjects: subject: Quantum Algebra (math.QA)
subject: Geometric Topology (math.GT)
subject: Representation Theory (math.RT)
subject: FOS: Mathematics

description: We give a new, algebraically computable formula for skein modules of closed 3-manifolds via Heegaard splittings. As an application, we prove that skein modules of closed 3-manifolds are finite-dimensional, resolving in the affirmative a conjecture of Witten.
description: 39 pages; final published version
BCS-like critical fluctuations with limited overlap of Cooper pairs in FeSe
Creators: name: Yang, Huan
name: Chen, Guanyu
name: Zhu, Xiyu
name: Xing, Jie
name: Wen, Hai-Hu
Publisher: name: arXiv
Year: 2017
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: In conventional superconductors, very narrow superconducting fluctuation regions are observed above $T_c$ because of the strong overlapping of Cooper pairs in a coherence volume. In the bulk form of iron chalcogenide superconductor FeSe, it is argued that the system may locate in the crossover region of BCS to BEC, indicating a strong superconducting fluctuation. In this respect, we have carried out measurements of magnetization, specific heat and Nernst effect on FeSe single crystals in order to investigate the superconducting fluctuation effect near $T_c$. The region of diamagnetization induced by superconducting fluctuation seems very narrow above $T_c$. The crossing point of temperature dependent magnetization curves measured at different magnetic fields, which appears in many systems of cuprate superconductors and is regarded as indication of strong critical fluctuation, is however absent. The magnetization data can be scaled based on the Ginzburg-Landau fluctuation theory for a quasi-two-dimensional system, but the scaling result cannot be described by the theoretical function of the fluctuation theory because of the limited fluctuation regions. The specific heat jump near $T_c$ is rather sharp without the trace of strong superconducting fluctuation. This is also supported by the Nernst effect measurements which indicate a very limited region for vortex motion above $T_c$. Associated with very small value of Ginzburg number and further analyses, we conclude that the superconducting fluctuation is very weak above $T_c$ in this material. Our results are strongly against the picture of significant phase fluctuation in FeSe single crystals, although the system has a very limited overlapping of Cooper pairs in the coherence volume. This dichotomy provides new insights into the superconducting mechanism when the system is with a dilute superfluid density.
description: 11 pages, 6 figures
Improved WKB approximation for quantum tunneling: Application to heavy ion fusion
Creators: name: Toubiana, A. J.
name: Canto, L. F.
name: Hussein, M. S.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Nuclear Theory (nucl-th)
subject: Nuclear Experiment (nucl-ex)
subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: In this paper we revisit the one-dimensional tunneling problem. We consider Kemble's approximation for the transmission coefficient. We show how this approximation can be extended to above-barrier energies by performing the analytical continuation of the radial coordinate to the complex plane. We investigate the validity of this approximation by comparing their predictions for the cross section and for the barrier distribution with the corresponding quantum mechanical results. We find that the extended Kemble's approximation reproduces the results of quantum mechanics with great accuracy.
description: 8 pages, 6 figures, in press, in European. Phys. Journal A (2017)
Image Recognition using Region Creep
Creators: name: Greer, Kieran
Publisher: name: arXiv
Year: 2019
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Image and Video Processing (eess.IV)
subject: FOS: Computer and information sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: This paper describes a new type of auto-associative image classifier that uses a shallow architecture with a very quick learning phase. The image is parsed into smaller areas and each area is saved directly for a region, along with the related output category. When a new image is presented, a direct match with each region is made and the best matching areas returned. Each area stores a list of the categories it belongs to, where there is a one-to-many relation between the input region and the output categories. The image classification process sums the category lists to return a preferred category for the whole image. These areas can overlap with each other and when moving from a region to its neighbours, there is likely to be only small changes in the area image part. It would therefore be possible to guess what the best image area is for one region by cumulating the results of its neighbours. This associative feature is being called 'Region Creep' and the cumulated region can be compared with train cases instead, when a suitable match is not found. Rules can be included and state that: if one set of pixels are present, another set should either be removed or should also be present, where this is across the whole image. The memory problems with a traditional auto-associative network may be less with this version and tests on a set of hand-written numbers have produced state-of-the-art results.
A Constructive Proof of Masser's Theorem
Creators: name: Barrios, Alexander J.
Publisher: name: arXiv
Year: 2019
Subjects: subject: Number Theory (math.NT)
subject: FOS: Mathematics
subject: 11G05

description: The Modified Szpiro Conjecture, equivalent to the $abc$ Conjecture, states that for each $ε>0$, there are finitely many rational elliptic curves satisfying $N_{E}^{6+ε}<\max\!\left\{ \left\vert c_{4}^{3}\right\vert,c_{6}^{2}\right\} $ where $c_{4}$ and $c_{6}$ are the invariants associated to a minimal model of $E$ and $N_{E}$ is the conductor of $E$. We say $E$ is a good elliptic curve if $N_{E}^{6}<\max\!\left\{ \left\vert c_{4}^{3}\right\vert,c_{6}^{2}\right\} $. Masser showed that there are infinitely many good Frey curves. Here we give a constructive proof of this assertion.
description: 9 pages
Comment on "Single-inclusive jet production in electron-nucleon collisions through next-to-next-to-leading order in perturbative QCD" [Phys. Lett. B 763, 52--59 (2016)]
Creators: name: Bodwin, Geoffrey T.
name: Braaten, Eric
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: In the cross section for single-inclusive jet production in electron-nucleon collisions, the distribution of a quark in an electron appears at next-to-next-to-leading order. The numerical calculations in Ref. [1] were carried out using a perturbative approximation for the distribution of a quark in an electron. We point out that that distribution receives nonperturbative QCD contributions that invalidate the perturbative approximation. Those nonperturbative effects enter into cross sections for hard-scattering processes through resolved-electron contributions and can be taken into account by determining the distribution of a quark in an electron phenomenologically.
description: 5 pages, minor corrections, version published in Physics Letters B
On Bowen's entropy inequality and almost specification for flows
Creators: name: Pacifico, Maria Jose
name: Sanhueza, Diego
Publisher: name: arXiv
Year: 2019
Subjects: subject: Dynamical Systems (math.DS)
subject: FOS: Mathematics
subject: 37AXX, 28D20

description: We study the Bowen topological entropy of generic and irregular points for certain dynamical systems. We define the topological entropy of noncompact sets for flows, analogous to Bowen's definition. We show that this entropy coincides with the Bowen topological entropy of the time-1 map on any set. We also show a Bowen's inequality for flows; namely, that the metric entropy with respect to every invariant measure for a continuous flow is an upper bound for the topological entropy of the set of generic points with respect to the same measure, and the equality is always true if the measure is ergodic. We propose a definition of almost specification property for flows and prove that a continuous flow has the almost specification property if the time-1 map satisfies this property. Using Bowen's inequality for flows, we show that every continuous flow with the almost specification property is saturated, extending a result of Meson and Vericat in [22]. Under the same hypotheses, we extend a result of Thompson on the entropy of irregular points in [30].
Physical meaning of the conserved quantities on anti-de Sitter geodesics
Creators: name: Cotaescu, Ion I.
Publisher: name: arXiv
Year: 2017
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: The geodesic motion on anti-de Sitter spacetimes is studied pointing out how the trajectories are determined by the ten independent conserved quantities associated to the specific SO(2,3) isometries of these manifolds. The new result is that there are two conserved SO(3) vectors which play the same role as the Runge-Lenz vector of the Kepler problem, determining the major and minor semiaxes of the ellipsoidal anti-de Sitter geodesics.
description: 4 pages (revtex4-1) no figures, to be published in PRD
A nonnegativity preserving scheme for the relaxed Cahn-Hilliard equation with single-well potential and degenerate mobility
Creators: name: Poulain, Alexandre
name: Bubba, Federica
Publisher: name: arXiv
Year: 2019
Subjects: subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics
subject: 35Q92, 65M60, 35K55, 35K65, 35K35, 35K67

description: We propose and analyze a finite element approximation of the relaxed Cahn-Hilliard equation with singular single-well potential of Lennard-Jones type and degenerate mobility that is energy stable and nonnegativity preserving. The Cahn-Hilliard model has recently been applied to model evolution and growth for living tissues: although the choices of degenerate mobility and singular potential are biologically relevant, they induce difficulties regarding the design of a numerical scheme. We propose a finite element scheme and we show that it preserves the physical bounds of the solutions thanks to an upwind approach adapted to the finite element method. Moreover, we show well-posedness, energy stability properties, and convergence of solutions of the numerical scheme. Finally, we validate our scheme by presenting numerical simulations in one and two dimensions.
A computational study of preconditioning techniques for the stochastic diffusion equation with lognormal coefficient
Creators: name: Aulisa, Eugenio
name: Capodaglio, Giacomo
name: Ke, Guoyi
Publisher: name: arXiv
Year: 2019
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics

description: We present a computational study of several preconditioning techniques for the GMRES algorithm applied to the stochastic diffusion equation with a lognormal coefficient discretized with the stochastic Galerkin method. The clear block structure of the system matrix arising from this type of discretization motivates the analysis of preconditioners designed according to a field-splitting strategy of the stochastic variables. This approach is inspired by a similar procedure used within the framework of physics based preconditioners for deterministic problems, and its application to stochastic PDEs represents the main novelty of this work. Our numerical investigation highlights the superior properties of the field-split type preconditioners over other existing strategies in terms of computational time and stochastic parameter dependence.
Ising model on random triangulations of the disk: phase transition
Creators: name: Chen, Linxiao
name: Turunen, Joonas
Publisher: name: arXiv
Year: 2020
Subjects: subject: Mathematical Physics (math-ph)
subject: Combinatorics (math.CO)
subject: Probability (math.PR)
subject: FOS: Physical sciences
subject: FOS: Mathematics
subject: 82B26, 05A16, 60K35

description: In [arXiv:1806.06668], we have studied the Boltzmann random triangulation of the disk coupled to an Ising model on its faces with Dobrushin boundary condition at its critical temperature. In this paper, we investigate the phase transition of this model by extending our previous results to arbitrary temperature: We compute the partition function of the model at all temperatures, and derive several critical exponents associated with the infinite perimeter limit. We show that the model has a local limit at any temperature, whose properties depend drastically on the temperature. At high temperatures, the local limit is reminiscent of the uniform infinite half-planar triangulation (UIHPT) decorated with a subcritical percolation. At low temperatures, the local limit develops a bottleneck of finite width due to the energy cost of the main Ising interface between the two spin clusters imposed by the Dobrushin boundary condition. This change can be summarized by a novel order parameter with a nice geometric meaning. In addition to the phase transition, we also generalize our construction of the local limit from the two-step asymptotic regime used in [arXiv:1806.06668] to a more natural diagonal asymptotic regime. We obtain in this regime a scaling limit related to the length of the main Ising interface, which coincides with predictions from the continuum theory of quantum surfaces (a.k.a.\ Liouville quantum gravity).
description: 66 pages, 9 figures, 7 tables. Version 6: Final proofread version. Accepted for publication in CIMP
A graph-based formulation for modeling macro-energy systems
Creators: name: Göke, Leonard
Publisher: name: arXiv
Year: 2020
Subjects: subject: Physics and Society (physics.soc-ph)
subject: FOS: Physical sciences

description: Averting the impending harms of climate change requires to replace fossil fuels with renewables as a primary source of energy. Non-electric renewable potential being limited, this implies extending the use of electricity generated from wind and solar beyond the power sector, either by direct electrification or synthetic fuels. Modeling the transformation towards such an energy system is challenging, because it imposes to consider fluctuations of wind and solar and the manifold ways the demand side could adjust to these fluctuations. This paper introduces a graph-based method to formulate energy system models to address these challenges. By organizing sets in rooted trees, two features to facilitate modeling high shares of renewables and sector integration are enabled. First, the method allows the level of temporal and spatial detail to be varied by energy carrier. This enables modeling with a high level of detail and a large scope, while keeping models computationally tractable. Second, the degree to which energy carriers are substitutable when converted, stored, transported, or consumed can be modeled to achieve a detailed but flexible representation of sector integration. An application of the formulation demonstrates that the variation of temporal detail achieves an average reduction in computation time of 70\%.
Deep Learning for Deepfakes Creation and Detection: A Survey
Creators: name: Nguyen, Thanh Thi
name: Nguyen, Quoc Viet Hung
name: Nguyen, Dung Tien
name: Nguyen, Duc Thanh
name: Huynh-The, Thien
name: Nahavandi, Saeid
name: Nguyen, Thanh Tam
name: Pham, Quoc-Viet
name: Nguyen, Cuong M.
Publisher: name: arXiv
Year: 2019
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Machine Learning (cs.LG)
subject: Image and Video Processing (eess.IV)
subject: FOS: Computer and information sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: Deep learning has been successfully applied to solve various complex problems ranging from big data analytics to computer vision and human-level control. Deep learning advances however have also been employed to create software that can cause threats to privacy, democracy and national security. One of those deep learning-powered applications recently emerged is deepfake. Deepfake algorithms can create fake images and videos that humans cannot distinguish them from authentic ones. The proposal of technologies that can automatically detect and assess the integrity of digital visual media is therefore indispensable. This paper presents a survey of algorithms used to create deepfakes and, more importantly, methods proposed to detect deepfakes in the literature to date. We present extensive discussions on challenges, research trends and directions related to deepfake technologies. By reviewing the background of deepfakes and state-of-the-art deepfake detection methods, this study provides a comprehensive overview of deepfake techniques and facilitates the development of new and more robust methods to deal with the increasingly challenging deepfakes.
Geometric orbital integrals and the center of the enveloping algebra
Creators: name: Bismut, Jean-Michel
name: Shen, Shu
Publisher: name: arXiv
Year: 2019
Subjects: subject: Differential Geometry (math.DG)
subject: Group Theory (math.GR)
subject: Representation Theory (math.RT)
subject: FOS: Mathematics

description: The purpose of this paper is to extend the explicit geometric evaluation of semisimple orbital integrals for smooth kernels for the Casimir operator obtained by the first author to the case of kernels for arbitrary elements in the center of the enveloping algebra.
Witten Anomaly in 4d Heterotic Compactificaitons with N = 2 Supersymmetry
Creators: name: Enoki, Yuichi
name: Sato, Yotaro
name: Watari, Taizan
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We showed that there is no SU(2) Witten anomaly in a large class of 4d N = 2 supersymmetric Heterotic string compactifications. The consistency conditions we consider are the modularity of the new supersymmetric index, the integrality of BPS indices, and the discrete Peccei-Quinn shift symmetries. We also found an example where these conditions are not sufficient to show that the theory is anomaly free. This suggests that there are more conditions in the worldsheet SCFT essential for consistent string compactifications.
description: v2: an error in (29) is corrected; conclusions remain unchanged
Interactive Walkable Floor maps - Guideline for teachers
Creators: name: Læssøe, Jeppe
Publisher: name: Zenodo
Year: 2024

description: Interactive Walkable Floor maps is platform aiming at scaffolding governance and educational processes. It was developed by an interdisciplinary group of researchers in collaboration with urban planners, schools and teachers as part of the EU H2020 funded project REGREEN, which aimed at fostering Nature-Based Solutions in cities. This guideline is targeted schools and teachers. Another guideline focusing on the process of designing Interactive Walkable Floor maps has been published by collagues from REGREEN, Sebastian Elze and Ellen Banzhaf, UFZ. It is available here on Zenodo as well.
Magnetic Field Effect on Dynamics of Entanglement for Time-dependent Harmonic Oscillator
Creators: name: Hab-arrih, Radouan
name: Jellal, Ahmed
name: Merdaci, Abdeldjalil
Publisher: name: arXiv
Year: 2019
Subjects: subject: Quantum Physics (quant-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We investigate the dynamics of entanglement, uncertainty and mixedness by solving time dependent Schrödinger equation for two-dimensional harmonic oscillator with time dependent frequency and coupling parameter subject to a static magnetic field. We compute the purities (global/marginal) and then calculate explicitly the linear entropy $S_{L}$ as well as logarithmic negativity $\mathcal{N}$ using the symplectic parametrization of vacuum state. We introduce the spectral decomposition to diagonalize the marginal state and get the expression of von Neumann entropy $S_{von}$ and establish its link with $S_{L}$. We use the Wigner formalism to derive the Heisenberg uncertainties and {show their dependencies on both $S_{L}$ and the coupling parameters $γ_{i}$ $ (i=1,2)$ of the quadrature term $x_{i}p_{i}$.} We graphically study the dynamics of the three features (entanglement, uncertainty, mixedness) and present the similar topology with respect to time. We show the effects of the magnetic field and quenched values of $J(t)$ and $ω_{2}(t)$ on these three dynamics, which lead eventually to control and handle them.
description: 20 pages, 9 figures. Clarifications and references added
Gram filtering and sinogram interpolation for pixel-basis in parallel-beam X-ray CT reconstruction
Creators: name: Shu, Ziyu
name: Entezari, Alireza
Publisher: name: arXiv
Year: 2020
Subjects: subject: Image and Video Processing (eess.IV)
subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Computer and information sciences

description: The key aspect of parallel-beam X-ray CT is forward and back projection, but its computational burden continues to be an obstacle for applications. We propose a method to improve the performance of related algorithms by calculating the Gram filter exactly and interpolating the sinogram signal optimally. In addition, the detector blur effect can be included in our model efficiently. The improvements in speed and quality for back projection and iterative reconstruction are shown in our experiments on both analytical phantoms and real CT images.