cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
DAWN: Domain-Adaptive Weakly Supervised Nuclei Segmentation via Cross-Task Interactions
Creators: name: Zhang, Ye
name: Wang, Yifeng
name: Fang, Zijie
name: Bian, Hao
name: Cai, Linghan
name: Wang, Ziyue
name: Zhang, Yongbing
Publisher: name: arXiv
Year: 2024
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: Weakly supervised segmentation methods have gained significant attention due to their ability to reduce the reliance on costly pixel-level annotations during model training. However, the current weakly supervised nuclei segmentation approaches typically follow a two-stage pseudo-label generation and network training process. The performance of the nuclei segmentation heavily relies on the quality of the generated pseudo-labels, thereby limiting its effectiveness. This paper introduces a novel domain-adaptive weakly supervised nuclei segmentation framework using cross-task interaction strategies to overcome the challenge of pseudo-label generation. Specifically, we utilize weakly annotated data to train an auxiliary detection task, which assists the domain adaptation of the segmentation network. To enhance the efficiency of domain adaptation, we design a consistent feature constraint module integrating prior knowledge from the source domain. Furthermore, we develop pseudo-label optimization and interactive training methods to improve the domain transfer capability. To validate the effectiveness of our proposed method, we conduct extensive comparative and ablation experiments on six datasets. The results demonstrate the superiority of our approach over existing weakly supervised approaches. Remarkably, our method achieves comparable or even better performance than fully supervised methods. Our code will be released in https://github.com/zhangye-zoe/DAWN.
description: 15 pages, 11 figures, 12 tables
title:   Examining the Indirect Effect of Trauma on Obsessive-Compulsive Symptoms through Responsibility/Threat Beliefs
Creators: name: Fenlon, Emily
Publisher: name: University of Kentucky Libraries
Year: 2022
Subjects: subject: FOS: Psychology
valueUri: http://www.oecd.org/science/inno/38235147.pdf

description: Inflated responsibility beliefs and threat estimations have been implicated in the etiology and maintenance of obsessive-compulsive (OC) symptoms. Research suggests that early life experiences that involve actual or perceived serious harm to oneself or others may lead to inflated responsibility/threat beliefs and OC symptoms. Research has yet to explore if traumatic experiences influence responsibility/threat beliefs or if the associations between trauma and OC symptoms are at all dependent on trauma’s influence on responsibility/threat beliefs. The present study aims to examine associations among exposure to potentially traumatic events (PTEs), responsibility/threat beliefs, and OC symptoms. A sample of 886 undergraduate students completed a battery of self-report questionnaires online, including measures of lifetime exposure to PTEs, pathways to responsibility beliefs, obsessive beliefs, including responsibility/threat estimation, and OC symptoms. Multiple regression using the PROCESS macro was used to examine the effects of cumulative exposure to PTEs on responsibility/threat beliefs and OC symptoms, the effects of responsibility/threat beliefs on OC symptoms, and the indirect effect of cumulative exposure to PTEs on OC symptoms through responsibility/threat beliefs. The three primary variables were significantly and positively correlated, and the indirect effect of cumulative exposure to PTEs on OC symptoms was significant, even when controlling for other obsessive belief categories. These findings suggest that trauma exposure may influence responsibility/threat beliefs to increase OC symptomatology, though longitudinal studies are needed to support this interpretation.
description: © 2022 Emily E. Fenlon
Supplementary information to "Raman spectroscopy and thermoelectric characterization of composite thin films of Cu2ZnSnS4 nanocrystals embedded in a conductive polymer PEDOT:PSS"
Creators: name: Havryliuk, Yevhenii
name: Dzhagan, Volodymyr
name: Karnaukhov, Anatolii
name: Selyshchev, Oleksandr
name: Hann, Julia
name: Zahn, Dietrich R.T.
Publisher: name: Zenodo
Year: 2022
Subjects: Cu2ZnSnS4 (CZTS)
nanocrystals
PEDOT:PSS
thermoelectric properties

description: Figure S1. (a) Fresh gel (upper photo) and after drying under the hood for 12 hours (bottom). (b) Raman spectra of fresh mixture, fresh gel, and gel after drying.
 Figure S2. Control experiment with effect of pure TGA solution on the Raman spectrum of PEDOT:PSS.
 Figure S3. Optical image of PEDOT:PSS film (a) before and (b) after 12J/cm2 FLA; and CZTS NCs film (c) before and (d) after 12J/cm2 FLA
Kiloparsec-Scale Simulations of Star Formation in Disk Galaxies. IV. Regulation of Galactic Star Formation Rates by Stellar Feedback
Creators: name: Butler, Michael J.
name: Tan, Jonathan C.
name: Teyssier, Romain
name: Rosdahl, Joakim
name: Van Loo, Sven
name: Nickerson, Sarah
Publisher: name: arXiv
Year: 2017
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Star formation from the interstellar medium of galactic disks is a basic process controlling the evolution of galaxies. Understanding the star formation rate in a local patch of a disk with a given gas mass is thus an important challenge for theoretical models. Here we simulate a kiloparsec region of a disk, following the evolution of self-gravitating molecular clouds down to subparsec scales, as they form stars that then inject feedback energy by dissociating and ionizing UV photons and supernova explosions. We assess the relative importance of each feedback mechanism. We find that $\rm H_2$-dissociating feedback results in the largest absolute reduction in star formation compared to the run with no feedback. Subsequently adding photoionization feedback produces a more modest reduction. Our fiducial models that combine all three feedback mechanisms yield, without fine-tuning, star formation rates that are in excellent agreement with observations, with $\rm H_2$-dissociating photons playing a crucial role. Models that only include supernova feedback---a common method in galaxy evolution simulations---settle to similar star formation rates, but with very different temperature and chemical states of the gas, and with very different spatial distributions of young stars.
description: 27 pages, 18 figures, accepted to ApJ
Supplementary information to "Raman spectroscopy and thermoelectric characterization of composite thin films of Cu2ZnSnS4 nanocrystals embedded in a conductive polymer PEDOT:PSS"
Creators: name: Havryliuk, Yevhenii
name: Dzhagan, Volodymyr
name: Karnauhov, Anatolii
name: Selyshchev, Oleksandr
name: Hann, Julia
name: Zahn, Dietrich R.T.
Publisher: name: Zenodo
Year: 2022
Subjects: Cu2ZnSnS4 (CZTS)
nanocrystals
PEDOT:PSS
thermoelectric properties

description: Figure S1. (a) Fresh gel (upper photo) and after drying under the hood for 12 hours (bottom). (b) Raman spectra of fresh mixture, fresh gel, and gel after drying.
 Figure S2. Control experiment with effect of pure TGA solution on the Raman spectrum of PEDOT:PSS.
 Figure S3. Optical image of PEDOT:PSS film (a) before and (b) after 12J/cm2 FLA; and CZTS NCs film (c) before and (d) after 12J/cm2 FLA
Learning Latent Representations for Speech Generation and Transformation
Creators: name: Hsu, Wei-Ning
name: Zhang, Yu
name: Glass, James
Publisher: name: arXiv
Year: 2017
Subjects: subject: Computation and Language (cs.CL)
subject: Machine Learning (cs.LG)
subject: Machine Learning (stat.ML)
subject: FOS: Computer and information sciences

description: An ability to model a generative process and learn a latent representation for speech in an unsupervised fashion will be crucial to process vast quantities of unlabelled speech data. Recently, deep probabilistic generative models such as Variational Autoencoders (VAEs) have achieved tremendous success in modeling natural images. In this paper, we apply a convolutional VAE to model the generative process of natural speech. We derive latent space arithmetic operations to disentangle learned latent representations. We demonstrate the capability of our model to modify the phonetic content or the speaker identity for speech segments using the derived operations, without the need for parallel supervisory data.
description: Accepted to Interspeech 2017
The chemical bond as an emergent phenomenon
Creators: name: Golden, Jon C.
name: Ho, Vinh
name: Lubchenko, Vassiliy
Publisher: name: arXiv
Year: 2017
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We first argue that the covalent bond and the various closed-shell interactions can be thought of as symmetry broken versions of one and the same interaction, viz., the multi-center bond. We use specially chosen molecular units to show that the symmetry breaking is controlled by density and electronegativity variation. We show that the bond order changes with bond deformation but in a step-like fashion, regions of near constancy separated by electronic localization transitions. These will often cause displacive transitions as well so that the bond strength, order, and length are established self-consistently. We further argue on the inherent relation of the covalent, closed-shell, and multi-center interactions with ionic and metallic bonding. All of these interactions can be viewed as distinct sectors on a phase diagram with density and electronegativity variation as control variables; the ionic and covalent/secondary sectors are associated with on-site and bond-order charge density wave respectively, the metallic sectorwith an electronic fluid. While displaying a contiguity at low densities, the metallic and ionic interactions represent distinct phases separated by discontinuous transitions at sufficiently high densities. Multi-center interactions emerge as a hybrid of the metallic and ionic bond that results from spatial coexistence of delocalized and localized electrons. In the present description, the issue of the stability of a compound is that of mutual miscibility of electronic fluids with distinct degrees of electron localization, supra-atomic ordering in complex inorganic compounds comes about naturally. The notions of electronic localization advanced hereby suggest a high throughput, automated procedure for screening candidate compounds and structures with regard to stability, without the need for computationally costly geometric optimization.
description: 21 pages and 25 figures in main text with a 16 page/37 figure supplement containing method details. New revision corrects minor typographical errors in text on pages 3 and 7, and captions for figures 5, 6 and 11
A Bosonization of $U_q(\widehat{sl}(M|N))$
Creators: name: Kojima, Takeo
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Algebra (math.QA)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: Exactly Solvable and Integrable Systems (nlin.SI)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: A bosonization of the quantum affine superalgebra $U_q(\widehat{sl}(M|N))$ is presented for an arbitrary level $k \in {\bf C}$. Screening operators that commute with $U_q(\widehat{sl}(M|N))$ are presented for the level $k \neq -M+N$.
description: LaTEX, 37 pages
SU(N) magnetism with ultracold molecules
Creators: name: Mukherjee, Bijit
name: Hutson, Jeremy M.
name: Hazzard, Kaden R. A.
Publisher: name: arXiv
Year: 2024
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Atomic Physics (physics.atom-ph)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Quantum systems with SU($N$) symmetry are paradigmatic settings for quantum many-body physics. They have been studied for the insights they provide into complex materials and their ability to stabilize exotic ground states. Ultracold alkaline-earth atoms were predicted to exhibit SU($N$) symmetry for $N=2I+1=1,2,\ldots,10$, where $I$ is the nuclear spin. Subsequent experiments have revealed rich many-body physics. However, alkaline-earth atoms realize this symmetry only for fermions with repulsive interactions. In this paper, we predict that ultracold molecules shielded from destructive collisions with static electric fields or microwaves exhibit SU($N$) symmetry, which holds because deviations of the s-wave scattering length from the spin-free values are only about 3\% for CaF with static-field shielding and are estimated to be even smaller for bialkali molecules. They open the door to $N$ as large as $32$ for bosons and $36$ for fermions. They offer important features unachievable with atoms, including bosonic systems and attractive interactions.
description: 11 pages, 8 figures, 2 tables
Analysis of Granular Packing Structure by Scattering of THz Radiation
Creators: name: Born, Philip
name: Holldack, Karsten
Publisher: name: arXiv
Year: 2017
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: Scattering methods are widespread used to characterize the structure and constituents of matter on small length scales. This motivates this introductory text on identifying prospective approaches to scattering-based methods for granular media. A survey to light scattering by particles and particle ensembles is given. It is elaborated why the established scattering methods using X-rays and visible light cannot in general be transferred to granular media. Spectroscopic measurements using Terahertz radiation are highlighted as they to probe the scattering properties of granular media, which are sensitive to the packing structure. Experimental details to optimize spectrometer for measurements on granular media are discussed. We perform transmission measurements on static and agitated granular media using Fourier-transform spectroscopy at the THz beamline of the BessyII storage ring. The measurements demonstrate the potential to evaluate degrees of order in the media and to track transient structural states in agitated bulk granular media.
description: 12 Pages, 9 Figures, 56 References
Be discs in coplanar circular binaries: Phase-locked variations of emission lines
Creators: name: Panoglou, Despina
name: Faes, Daniel M.
name: Carciofi, Alex C.
name: Okazaki, Atsuo T.
name: Baade, Dietrich
name: Rivinius, Thomas
name: Fernandes, Marcelo Borges
Publisher: name: arXiv
Year: 2017
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The first results of radiative transfer calculations on decretion discs of binary Be stars are presented. A smoothed particle hydrodynamics code computes the structure of Be discs in coplanar circular binary systems for a range of orbital and disc parameters. The resulting disc configuration consists of two spiral arms, and can be given as input into a Monte Carlo code, which calculates the radiative transfer along the line of sight for various observational coordinates. Making use of the property of steady disc structure in coplanar circular binaries, observables are computed as functions of the orbital phase. Orbital-phase series of line profiles are given for selected parameter sets under various viewing angles, to allow comparison with observations. Flat-topped profiles with and without superimposed multiple structures are reproduced, showing, for example, that triple-peaked profiles do not have to be necessarily associated with warped discs and misaligned binaries. It is demonstrated that binary tidal effects give rise to phase-locked variability of the violet-to-red (V/R) ratio of hydrogen emission lines. The V/R ratio exhibits two maxima per cycle; in certain cases those maxima are equal, leading to a clear new V/R cycle every half orbital period. This study opens a way in identifying binaries and in constraining the parameters of binary systems that exhibit phase-locked variations induced by tidal interaction with a companion star.
description: 12 pages, 16 figures; accepted for publication by MNRAS
Stable exponential cosmological solutions with zero variation of $G$ and three different Hubble-like parameters in the Einstein-Gauss-Bonnet model with a $Λ$-term
Creators: name: Ernazarov, K. K.
name: Ivashchuk, V. D.
Publisher: name: arXiv
Year: 2017
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We consider a $D$-dimensional gravitational model with a Gauss-Bonnet term and the cosmological term $Λ$. We restrict the metrics to diagonal cosmological ones and find for certain $Λ$ a class of solutions with exponential time dependence of three scale factors, governed by three non-coinciding Hubble-like parameters $H >0$, $h_1$ and $h_2$, corresponding to factor spaces of dimensions $m > 2$, $k_1 > 1$ and $k_2 > 1$, respectively, with $k_1 \neq k_2$ and $D = 1 + m + k_1 + k_2$. Any of these solutions describes an exponential expansion of $3d$ subspace with Hubble parameter $H$ and zero variation of the effective gravitational constant $G$. We prove the stability of these solutions in a class of cosmological solutions with diagonal metrics.
description: 16 pages, Latex, no figures, prepared for a talk at 16th Russian Gravitational Conference - International Conference on General Relativity, Cosmology and Astrophysics (Kaliningrad, 24-30 June); several typos are eliminated
Reducibility of the Quantum Harmonic Oscillator in $d$-dimensions with Polynomial Time Dependent Perturbation
Creators: name: Bambusi, Dario
name: Grebert, Benoit
name: Maspero, Alberto
name: Robert, Didier
Publisher: name: arXiv
Year: 2017
Subjects: subject: Analysis of PDEs (math.AP)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 37K55, 35J10

description: We prove a reducibility result for a quantum harmonic oscillator in arbitrary dimensions with arbitrary frequencies perturbed by a linear operator which is a polynomial of degree two in $x_j$, $-i \partial_j$ with coefficients which depend quasiperiodically on time.
description: fixed some misprints
A Unified tool to estimate Distances, Ages and Masses (UniDAM) from spectrophotometric data
Creators: name: Mints, Alexey
name: Hekker, Saskia
Publisher: name: arXiv
Year: 2017
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Galactic archaeology - the study of the formation and evolution of the Milky Way by reconstructing its past from its current constituents - requires precise and accurate knowledge of stellar parameters for as many stars as possible. To achieve this a number of large spectroscopic surveys have been undertaken and are still ongoing. So far consortia carrying out the different spectroscopic surveys have used different tools to determine stellar parameters of stars from their derived effective temperatures (Teff), surface gravities (log g) and metallicities ([Fe/H]) possibly combined with photometric, astrometric, interferometric or asteroseismic information. Here we aim to homogenise the stellar characterisation by applying a unified tool to a large set of publicly available spectrophotometric data. We use spectroscopic data from a variety of large surveys combined with infra-red photometry from 2MASS and AllWISE and compare these in a Bayesian manner with PARSEC isochrones to derive probability density functions (PDFs) for stellar masses, ages and distances. We treat PDFs of pre-helium-core burning, helium-core burning and post helium-core burning solutions as well as different peaks in multi-modal PDFs (i.e. each unimodal sub-PDF) of the different evolutionary phases separately. For over 2.5 million stars we report mass, age and distance estimate for each evolutionary phase and unimodal sub-PDF. We report Gaussian, skewed Gaussian, truncated Gaussian, modified truncated exponential distribution or truncated Student's t-distribution functions to represent each sub-PDF, allowing to reconstruct detailed PDFs. Comparisons with stellar parameter estimates from the literature show good agreement within uncertainties. We present UniDAM - the unified tool applicable to spectrophotometric data of different surveys to obtain a homogenised set of stellar parameters.
Magnetic Proximity Effects in Transition-Metal Dichalcogenides: Converting Excitons
Creators: name: Scharf, Benedikt
name: Xu, Gaofeng
name: Matos-Abiague, Alex
name: Žutić, Igor
Publisher: name: arXiv
Year: 2017
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: The two-dimensional character and reduced screening in monolayer transition-metal dichalcogenides (TMDs) lead to the ubiquitous formation of robust excitons with binding energies orders of magnitude larger than in bulk semiconductors. Focusing on neutral excitons, bound electron-hole pairs, that dominate the optical response in TMDs, it is shown that they can provide fingerprints for magnetic proximity effects in magnetic heterostructures. These proximity effects cannot be described by the widely used single-particle description, but instead reveal the possibility of a conversion between optically inactive and active excitons by rotating the magnetization of the magnetic substrate. With recent breakthroughs in fabricating Mo- and W-based magnetic TMD-heterostructures, this emergent optical response can be directly tested experimentally.
description: 10 pages, pages 7-10 contain supplemental material
Gustafson-Rakha-Type Elliptic Hypergeometric Series
Creators: name: Rosengren, Hjalmar
Publisher: name: arXiv
Year: 2017
Subjects: subject: Classical Analysis and ODEs (math.CA)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: We prove a multivariable elliptic extension of Jackson's summation formula conjectured by Spiridonov. The trigonometric limit case of this result is due to Gustafson and Rakha. As applications, we obtain two further multivariable elliptic Jackson summations and two multivariable elliptic Bailey transformations. The latter four results are all new even in the trigonometric case.
Variational approximations for stochastic dynamics on graphs
Creators: name: Pelizzola, Alessandro
name: Pretti, Marco
Publisher: name: arXiv
Year: 2017
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We investigate different mean-field-like approximations for stochastic dynamics on graphs, within the framework of a cluster-variational approach. In analogy with its equilibrium counterpart, this approach allows one to give a unified view of various (previously known) approximation schemes, and suggests quite a systematic way to improve the level of accuracy. We compare the different approximations with Monte Carlo simulations on a reversible (susceptible-infected-susceptible) discrete-time epidemic-spreading model on random graphs.
description: 29 pages, 5 figures. Minor revisions. IOP-styled
title: The Effect of pH on Synaptic Transmission at the Neuromuscular Junction in Drosophila melanogaster
Creators: name: Stanley, Catherine
Publisher: name: University of Kentucky Libraries
Year: 2020
Subjects: subject: FOS: Biological sciences
valueUri: http://www.oecd.org/science/inno/38235147.pdf

description: Synaptic transmission is the main avenue of neuronal communication and can be affected by a multitude of factors, both intracellularly and extracellularly. The effects of pH changes on synaptic transmission have been studied for many years across many different models. Intracellular acidification at the presynaptic terminal is known to occur with increased neuronal activity and can also occur in pathological conditions. The effects of these pH alterations are therefore an important area of study. Here, intracellular acidification using either propionic acid or the ammonium chloride pre-pulse technique was examined for the effects on both spontaneous and evoked synaptic transmission at the neuromuscular junction in larval Drosophila. The fly NMJ is glutamatergic and is used as a model of graded synaptic transmission. Propionic acid is shown to increase spontaneous quantal event frequency while also attenuating evoked transmission and depolarizing the cell. Ammonium chloride withdrawal has more diverse and complex effects that are shown to be dose- and condition-dependent. These studies are significant in further developing a model of the effects of intracellular acidification on evoked and non-evoked synaptic transmission.
description: © 2020 Catherine Stanley
title: Towards a thermally complete study of inflationary predictions
Creators: name: Procacci, Simona
Publisher: name: Universität Bern
Year: 2023
Subjects: subject: 530 Physics

description: This monograph presents theoretical efforts aiming at precision probes for the model of cosmological inflation. The latter is considered for its virtue of explaining the origin of primordial perturbations. However, the description of the transition from a vacuum- to a radiation-dominated universe is not yet robust. Asking for a realistic framework, we study the effects of including interactions among the inflaton field and a thermal plasma.
 The concrete setup is the one of [1], where we investigate the dynamics of inflation in the presence of a heat bath. In [3] real-time lattice simulations are used to improve on the estimation of the thermal friction felt by the inflaton field. We compute the contributions to the gravitational wave signal from the warming-up period after inflation [2], and implement thermal corrections to tensor fluctuations produced during inflation [4]. Depending on the maximal temperature reached after inflation, the high-frequency part of [2] can be constrained with Neff, whereas the low-frequency part of [4] may be probed with LISA or ET. To explore these prospects, in [5] we study the dependence of the temperature evolution on the confinement scale of the gauge plasma.
The text presented here shows partial overlap with the published material. Nonetheless, the exposition commits to be self-contained, including a pedagogical review of cosmological perturbation theory and inflation, and deriving results through detailed calculations.

 // List of publications

[1] M. Laine and S. Procacci, Minimal warm inflation with complete medium response, JCAP 06 (2021), 031 [2102.09913].

[2] P. Klose, M. Laine and S. Procacci, Gravitational wave background from non-Abelian reheating after axion-like inflation, JCAP 05 (2022), 021 [2201.02317].

[3] M. Laine, L. Niemi, S. Procacci and K. Rummukainen, Shape of the hot topological charge density spectral function, JHEP 11 (2022), 126 [2209.13804].

[4] P. Klose, M. Laine and S. Procacci, Gravitational wave background from vacuum and thermal fluctuations during axion-like inflation, JCAP 12 (2022), 020 [2210.11710].

[5] H. Kolesova, M. Laine and S. Procacci, Maximal temperature of strongly-coupled dark sectors, JHEP 05 (2023), 239 [2303.17973].
DC Conductivities with Momentum Dissipation in Horndeski Theories
Creators: name: Jiang, Wei-Jian
name: Liu, Hai-Shan
name: Lu, H.
name: Pope, C. N.
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: In this paper, we consider two four-dimensional Horndeski-type gravity theories with scalar fields that give rise to solutions with momentum dissipation in the dual boundary theories. Firstly, we study Einstein-Maxwell theory with a Horndeski axion term and two additional free axions which are responsible for momentum dissipation. We construct static electrically charged AdS planar black hole solutions in this theory and calculate analytically the holographic DC conductivity of the dual field theory. We then generalize the results to include magnetic charge in the black hole solution. Secondly, we analyze Einstein-Maxwell theory with two Horndeski axions which are used for momentum dissipation. We obtain AdS planar black hole solutions in the theory and we calculate the holographic DC conductivity of the dual field theory. The theory has a critical point $α+ γΛ= 0$, beyond which the kinetic terms of the Horndeski axions become ghost-like. The conductivity as a function of temperature behaves qualitatively like that of a conductor below the critical point, becoming semiconductor-like at the critical point. Beyond the critical point, the ghost-like nature of the Horndeski fields is associated with the onset of unphysical singular or negative conductivities. Some further generalisations of the above theories are considered also.
description: 23 pages, 1 figure. Typos corrected and reference added
Quantum friction between graphene sheets
Creators: name: Farias, M. Belén
name: Fosco, César D.
name: Lombardo, Fernando C.
name: Mazzitelli, Francisco D.
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We study the Casimir friction phenomenon in a system consisting of two flat, infinite, and parallel graphene sheets, which are coupled to the vacuum electromagnetic (EM) field. Those couplings are implemented, in the description we use, by means of specific terms in the effective action for the EM field. They incorporate the distinctive properties of graphene, as well as the relative sliding motion of the sheets. Based on this description, we evaluate two observables due to the same physical effect: the probability of vacuum decay and the frictional force. The system exhibits a threshold for frictional effects, namely, they only exist if the speed of the sliding motion is larger than the Fermi velocity of the charge carriers in graphene.
description: 16 pages, 3 figures. Minor corrections
Continuum balances from extended Hamiltonian dynamics
Creators: name: Giusteri, Giulio G.
name: Podio-Guidugli, Paolo
name: Fried, Eliot
Publisher: name: arXiv
Year: 2017
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: The classical procedure devised by Irving and Kirkwood in 1950 and completed slightly later by Noll produces counterparts of the basic balance laws of standard continuum mechanics starting from an ordinary Hamiltonian description of the dynamics of a system of material points. Post-1980 molecular dynamics simulations of the time evolution of such systems use extended Hamiltonians such as those introduced by Andersen, Nosé, and Parrinello and Rahman. The additional terms present in these extensions affect the statistical properties of the system so as to capture certain target phenomenologies that would otherwise be beyond reach. We here propose a physically consistent application of the Irving-Kirkwood-Noll procedure to extended Hamiltonian systems of material points. Our procedure produces balance equations at the continuum level featuring non-standard terms, because the presence of auxiliary degrees of freedom gives rise to additional fluxes and sources that influence the thermodynamic and transport properties of the continuum model. Being aware of the additional contributions may prove crucial when designing multiscale computational schemes in which information is exchanged between the atomistic and continuum levels.
Leading twist generalized parton distributions and spin densities in a proton
Creators: name: Maji, Tanmay
name: Mondal, Chandan
name: Chakrabarti, Dipankar
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We evaluate both chirally even and odd generalized parton distributions(GPDs) in the leading twist in a recently proposed quark-diquark model for the proton where the light front wavefunctions are constructed from the soft-wall AdS/QCD prediction. The GPDs in transverse impact parameter space give the spin densities for different quark and proton polarizations. For longitudinally polarized proton only chiral even GPDs contribute but for transversely polarized proton both chiral even and chiral odd GPDs contribute to the spin densities. We present a detail study of the spin densities in this model.
description: 27 pages, 12 figures; version published in PRD
Temperature independent band structure of WTe2 as observed from ARPES
Creators: name: Thirupathaiah, S.
name: Jha, Rajveer
name: Pal, Banabir
name: Matias, J. S.
name: Das, P. Kumar
name: Vobornik, I.
name: Ribeiro, R. A.
name: Sarma, D. D.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Extremely large magnetoresistance (XMR), observed in transition metal dichalcogendies, WTe$_2$, has attracted recently a great deal of research interests as it shows no sign of saturation up to the magnetic field as high as 60 T, in addition to the presence of type-II Weyl fermions. Currently, there has been a lot of discussion on the role of band structure changes on the temperature dependent XMR in this compound. In this contribution, we study the band structure of WTe$_2$ using angle-resolved photoemission spectroscopy (ARPES) and first-principle calculations to demonstrate that the temperature dependent band structure has no substantial effect on the temperature dependent XMR as our measurements do not show band structure changes on increasing the sample temperature between 20 and 130 K. We further observe an electronlike surface state, dispersing in such a way that it connects the top of bulk holelike band to the bottom of bulk electronlike band. Interestingly, similar to bulk states, the surface state is also mostly intact with the sample temperature. Our results provide invaluable information in shaping the mechanism of temperature dependent XMR in WTe$_2$.
description: 7 pages, 3 figures. arXiv admin note: text overlap with arXiv:1705.07217
Constraining the scalar septet model through vector boson scattering
Creators: name: Harris, Mary-Jean
name: Logan, Heather E.
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: The scalar septet model extends the Standard Model Higgs sector by an isospin septet with hypercharge chosen to preserve $ρ\equiv M_W^2/M_Z^2 \cos^2θ_W = 1$. In this paper we constrain the model at high septet masses using perturbative unitarity of longitudinal vector boson scattering amplitudes. We also apply the constraints from LHC searches for doubly-charged Higgs bosons produced in vector boson fusion, which constrain the model at lower septet masses. We point out some important differences between the septet model and extended Higgs models that preserve custodial symmetry in the scalar spectrum.
description: 9 pages, 1 figure. v2: reference added, minor improvements to text, version accepted by PRD
Exploring Remote Research Supervision: Challenges and Opportunities
Creators: name: Davis, Brian
Publisher: name: Zenodo
Year: 2021
Subjects: Remote Supervision
Remote Research Supervision
Academic Practice
Research Supervision
Online Supervision
Doctoral Supervision
Covid

description: The rapid advancement of information technologies combined with economic challenges in recent years has generated a need for universities to compete effectively for new sources of funding while also maintaining cost-effective and competitive operations. This has resulted in a significant rise in distance education programmes. The current COVID global pandemic has made the task of remote teaching and in particular remote postgraduate supervision more demanding. Remote supervision is in general under-researched field requiring empirical validation. Furthermore, although there are a number of supervision models, none have not been applied to remote supervision, so there are open questions concerning if and how they reflect the supervisor’s experience of supervising research students remotely. This study involved conducting a focus group with academics at the Department of Computing, Dublin City University(DCU) engaged in remote (online) research supervision. The Focus group explored whether/how supervisory practices changed as campuses were closed during the Covid-19 pandemic. The purpose of the focus group is to generate data for reflexive thematic analysis, the aim being to capture knowledge for understanding and hypothesis generation for future research. The results of reflexive thematic analysis indicate that supervisors engaged in remote supervision report negative experiences in the context of i) providing students access to adequate research infrastructure ii) enabling student research enculturation iii) ensuring the development of students’ critical thinking skills and vi) building a strong student supervisor relationship. The study makes a novel research contribution in that it validates and elaborates on the challenges of remote supervision as identified. Furthermore, the analysis underscores also how existing models of research supervision are impacted negatively by distance learning and will require adaptation to a remote context. Finally, the study provides a series of recommendations with respect to research gaps (challenges and opportunities) in remote supervision that require further exploration and validation.
description: This is pre-examination copy. The MA was awarded in April 2022.
Measurement of the linear thermo-optical coefficient of Ga$_{0.51}$In$_{0.49}$P using photonic crystal nanocavities
Creators: name: Sokolov, Sergei
name: Lian, Jin
name: Combrié, Sylvain
name: De Rossi, Alfredo
name: Mosk, Allard P.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Optics (physics.optics)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Ga$_{0.51}$In$_{0.49}$P is a promising candidate for thermally tunable nanophotonic devices due to its low thermal conductivity. In this work we study its thermo-optical response. We obtain the linear thermo-optical coefficient $dn/dT=2.0\pm0.3\cdot 10^{-4}\,\rm{K}^{-1}$ by investigating the transmission properties of a single mode-gap photonic crystal nanocavity.
description: 7 pages, 4 figures
Reformulation of the symmetries of first-order general relativity
Creators: name: Montesinos, Merced
name: Gonzalez, Diego
name: Celada, Mariano
name: Diaz, Bogar
Publisher: name: arXiv
Year: 2017
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: We report a new internal gauge symmetry of the n-dimensional Palatini action with cosmological term (n>3) that is the generalization of three-dimensional local translations. This symmetry is obtained through the direct application of the converse of Noether's second theorem on the theory under consideration. We show that diffeomorphisms can be expressed as linear combinations of it and local Lorentz transformations with field-dependent parameters up to terms involving the variational derivatives of the action. As a result, the new internal symmetry together with local Lorentz transformations can be adopted as the fundamental gauge symmetries of general relativity. Although their gauge algebra is open in general, it allows us to recover, without resorting to the equations of motion, the very well-known Lie algebra satisfied by translations and Lorentz transformations in three dimensions. We also report the analog of the new gauge symmetry for the Holst action with cosmological term, finding that it explicitly depends on the Immirzi parameter. The same result concerning its relation to diffeomorphisms and the open character of the gauge algebra also hold in this case. Finally, we consider the non-minimal coupling of a scalar field to gravity in n dimensions and establish that the new gauge symmetry is affected by this matter field. Our results indicate that general relativity in dimension greater than three can be thought of as a gauge theory.
description: It matches published version in CQG
Two-photon interference from two blinking quantum emitters
Creators: name: Jöns, Klaus D.
name: Stensson, Katarina
name: Reindl, Marcus
name: Swillo, Marcin
name: Huo, Yongheng
name: Zwiller, Val
name: Rastelli, Armando
name: Trotta, Rinaldo
name: Björk, Gunnar
Publisher: name: arXiv
Year: 2017
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We investigate the effect of blinking on the two-photon interference measurement from two independent quantum emitters. We find that blinking significantly alters the statistics in the second-order intensity correlation function g$^{(2)}(τ)$ and the outcome of two-photon interference measurements performed with independent quantum emitters. We theoretically demonstrate that the presence of blinking can be experimentally recognized by a deviation from the g$^{(2)}_{D}(0)=0.5$ value when distinguishable photons impinge on a beam splitter. Our results show that blinking imposes a mandatory cross-check measurement to correctly estimate the degree of indistinguishablility of photons emitted by independent quantum emitters.
A Macdonald refined topological vertex
Creators: name: Foda, Omar
name: Wu, Jian-Feng
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: We consider the refined topological vertex of Iqbal et al, as a function of two parameters (x, y), and deform it by introducing Macdonald parameters (q, t), as in the work of Vuletic on plane partitions, to obtain 'a Macdonald refined topological vertex'. In the limit q -> t, we recover the refined topological vertex of Iqbal et al. In the limit x -> y, we obtain a qt-deformation of the topological vertex of Aganagic et al. Copies of the vertex can be glued to obtain qt-deformed 5D instanton partition functions that have well-defined 4D limits and, for generic values of (q, t), contain infinite-towers of poles for every pole in the limit q -> t.
description: 48 pages, added introductory material and references, corrected typos, version to appear in Journal of Physics A Special Issue dedicated to Professor Petr Kulish
MoTe2 : An uncompensated semimetal with extremely large magnetoresistance
Creators: name: Thirupathaiah, S.
name: Jha, Rajveer
name: Pal, Banabir
name: Matias, J. S.
name: Das, P. Kumar
name: Sivakumar, P. K.
name: Vobornik, I.
name: Plumb, N. C.
name: Shi, M.
name: Ribeiro, R. A.
name: Sarma, D. D.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Transition-metal dichalcogenides (WTe$_2$ and MoTe$_2$) have drawn much attention, recently, because of the nonsaturating extremely large magnetoresistance (XMR) observed in these compounds in addition to the predictions of likely type-II Weyl semimetals. Contrary to the topological insulators or Dirac semimetals where XMR is linearly dependent on the field, in WTe$_2$ and MoTe$_2$ the XMR is nonlinearly dependent on the field, suggesting an entirely different mechanism. Electron-hole compensation has been proposed as a mechanism of this nonsaturating XMR in WTe$_2$, while it is yet to be clear in the case of MoTe$_2$ which has an identical crystal structure of WTe$_2$ at low temperatures. In this paper, we report low-energy electronic structure and Fermi surface topology of MoTe$_2$ using angle-resolved photoemission spectrometry (ARPES) technique and first-principle calculations, and compare them with that of WTe$_2$ to understand the mechanism of XMR. Our measurements demonstrate that MoTe$_2$ is an uncompensated semimetal, contrary to WTe$_2$ in which compensated electron-hole pockets have been identified, ruling out the applicability of charge compensation theory for the nonsaturating XMR in MoTe$_2$. In this context, we also discuss the applicability of the existing other conjectures on the XMR of these compounds.
description: 9 pages, 6 figs
Approximate Nearest Neighbour Search on Dynamic Datasets: An Investigation
Creators: name: Harwood, Ben
name: Dezfouli, Amir
name: Chades, Iadine
name: Sanderson, Conrad
Publisher: name: arXiv
Year: 2024
Subjects: subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Approximate k-Nearest Neighbour (ANN) methods are often used for mining information and aiding machine learning on large scale high-dimensional datasets. ANN methods typically differ in the index structure used for accelerating searches, resulting in various recall/runtime trade-off points. For applications with static datasets, runtime constraints and dataset properties can be used to empirically select an ANN method with suitable operating characteristics. However, for applications with dynamic datasets, which are subject to frequent online changes (like addition of new samples), there is currently no consensus as to which ANN methods are most suitable. Traditional evaluation approaches do not consider the computational costs of updating the index structure, as well as the rate and size of index updates. To address this, we empirically evaluate 5 popular ANN methods on two main applications (online data collection and online feature learning) while taking into account these considerations. Two dynamic datasets are used, derived from the SIFT1M dataset with 1 million samples and the DEEP1B dataset with 1 billion samples. The results indicate that the often used k-d trees method is not suitable on dynamic datasets as it is slower than a straightforward baseline exhaustive search method. For online data collection, the Hierarchical Navigable Small World Graphs method achieves a consistent speedup over baseline across a wide range of recall rates. For online feature learning, the Scalable Nearest Neighbours method is faster than baseline for recall rates below 75%.
Lifting of curves with automorphisms
Creators: name: Obus, Andrew
Publisher: name: arXiv
Year: 2017
Subjects: subject: Algebraic Geometry (math.AG)
subject: Number Theory (math.NT)
subject: FOS: Mathematics
subject: Primary: 14H37, 12F10, Secondary: 11G20, 12G15, 13B05, 13K05, 14G22, 14H30

description: The lifting problem for curves with automorphisms asks whether we can lift a smooth projective characteristic p curve with a group G of automorphisms to characteristic zero. This was solved by Grothendieck when G acts with prime-to-p stabilizers, and there has been much progress over the last few decades in the wild case. We survey the techniques and obstructions for this lifting problem, aiming at a reader whose background is limited to scheme theory at the level of Hartshorne's book. Throughout, we include numerous examples and clarifying remarks. We also provide a list of open questions.
description: Updates to Theorem 6.20 and Proposition 6.23. Now 44 pages