cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Optimization of the anisotropic Cheeger constant with respect to the anisotropy
Creators: name: Parini, Enea
name: Saracco, Giorgio
Publisher: name: arXiv
Year: 2022
Subjects: subject: Optimization and Control (math.OC)
subject: Metric Geometry (math.MG)
subject: FOS: Mathematics

description: Given an open, bounded set $Ω$ in $\mathbb{R}^N$, we consider the minimization of the anisotropic Cheeger constant $h_K(Ω)$ with respect to the anisotropy $K$, under a volume constraint on the associated unit ball. In the planar case, under the assumption that $K$ is a convex, centrally symmetric body, we prove the existence of a minimizer. Moreover, if $Ω$ is a ball, we show that the optimal anisotropy $K$ is not a ball and that, among all regular polygons, the square provides the minimal value.
Human pose estimation via Convolutional Part Heatmap Regression
Creators: name: Bulat, Adrian
name: Tzimiropoulos, Georgios
Publisher: name: arXiv
Year: 2016
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: This paper is on human pose estimation using Convolutional Neural Networks. Our main contribution is a CNN cascaded architecture specifically designed for learning part relationships and spatial context, and robustly inferring pose even for the case of severe part occlusions. To this end, we propose a detection-followed-by-regression CNN cascade. The first part of our cascade outputs part detection heatmaps and the second part performs regression on these heatmaps. The benefits of the proposed architecture are multi-fold: It guides the network where to focus in the image and effectively encodes part constraints and context. More importantly, it can effectively cope with occlusions because part detection heatmaps for occluded parts provide low confidence scores which subsequently guide the regression part of our network to rely on contextual information in order to predict the location of these parts. Additionally, we show that the proposed cascade is flexible enough to readily allow the integration of various CNN architectures for both detection and regression, including recent ones based on residual learning. Finally, we illustrate that our cascade achieves top performance on the MPII and LSP data sets. Code can be downloaded from http://www.cs.nott.ac.uk/~psxab5/
description: accepted to ECCV 2016
Semi-supervised cross-lingual speech emotion recognition
Creators: name: Agarla, Mirko
name: Bianco, Simone
name: Celona, Luigi
name: Napoletano, Paolo
name: Petrovsky, Alexey
name: Piccoli, Flavio
name: Schettini, Raimondo
name: Shanin, Ivan
Publisher: name: arXiv
Year: 2022
Subjects: subject: Sound (cs.SD)
subject: Artificial Intelligence (cs.AI)
subject: Machine Learning (cs.LG)
subject: Audio and Speech Processing (eess.AS)
subject: FOS: Computer and information sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: Performance in Speech Emotion Recognition (SER) on a single language has increased greatly in the last few years thanks to the use of deep learning techniques. However, cross-lingual SER remains a challenge in real-world applications due to two main factors: the first is the big gap among the source and the target domain distributions; the second factor is the major availability of unlabeled utterances in contrast to the labeled ones for the new language. Taking into account previous aspects, we propose a Semi-Supervised Learning (SSL) method for cross-lingual emotion recognition when only few labeled examples in the target domain (i.e. the new language) are available. Our method is based on a Transformer and it adapts to the new domain by exploiting a pseudo-labeling strategy on the unlabeled utterances. In particular, the use of a hard and soft pseudo-labels approach is investigated. We thoroughly evaluate the performance of the proposed method in a speaker-independent setup on both the source and the new language and show its robustness across five languages belonging to different linguistic strains. The experimental findings indicate that the unweighted accuracy is increased by an average of 40% compared to state-of-the-art methods.
rFerns: An Implementation of the Random Ferns Method for General-Purpose Machine Learning
Creators: name: Kursa, Miron B.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Machine Learning (cs.LG)
subject: Machine Learning (stat.ML)
subject: FOS: Computer and information sciences

description: In this paper I present an extended implementation of the Random ferns algorithm contained in the R package rFerns. It differs from the original by the ability of consuming categorical and numerical attributes instead of only binary ones. Also, instead of using simple attribute subspace ensemble it employs bagging and thus produce error approximation and variable importance measure modelled after Random forest algorithm. I also present benchmarks' results which show that although Random ferns' accuracy is mostly smaller than achieved by Random forest, its speed and good quality of importance measure it provides make rFerns a reasonable choice for a specific applications.
One-way quantum deficit for $2\otimes d$ systems
Creators: name: Ye, Biao-Liang
name: Fei, Shao-Ming
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We investigate one-way quantum deficit for $2\otimes d$ systems. Analytical expressions of one-way quantum deficit under both von Neumann measurement and weak measurement are presented. As an illustration, qubit-qutrit systems are studied in detail. It is shown that there exists non-zero one-way quantum deficit even quantum entanglement vanishes. Moreover, one-way quantum deficit via weak measurement turns out to be weaker than that via von Neumann measurement. The dynamics of entanglement and one-way quantum deficit under dephasing channels is also investigated.
description: 9 pages, 2 figures
Nonlinear Oscillations and Bifurcations in Silicon Photonic Microresonators
Creators: name: Abrams, Daniel M.
name: Slawik, Alex
name: Srinivasan, Kartik
Publisher: name: arXiv
Year: 2013
Subjects: subject: Adaptation and Self-Organizing Systems (nlin.AO)
subject: Mathematical Physics (math-ph)
subject: Dynamical Systems (math.DS)
subject: Optics (physics.optics)
subject: FOS: Physical sciences
subject: FOS: Mathematics
subject: 78A60 (Primary), 37Gxx, 34C25, 34C26, 34C15 (Secondary)

description: Silicon microdisks are optical resonators that can exhibit surprising nonlinear behavior. We present a new analysis of the dynamics of these resonators, elucidating the mathematical origin of spontaneous oscillations and deriving predictions for observed phenomena such as a frequency comb spectrum with MHz-scale repetition rate. We test predictions through laboratory experiment and numerical simulation.
description: Main text: 5 pages, 6 figures. Supplemental material: 12 pages, 8 figures
Let's Go Extreme with Roman: Observing z ~ 0. 5 – 2 low and high EW ELGs
Creators: name: Khostovan, Ali Ahmad
Publisher: name: Zenodo
Year: 2023
Subjects: Surveys of the flickering universe and galaxy formation

description: Planned grism surveys with Roman will shed much light on star formation histories of galaxies near cosmic noon. Hα Equivalent Width (EW; observational proxy for specific star formation rate; sSFR) is one tracer of episodic SF activity. In this talk, I will present a new methodology of constraining intrinsic z ~ 0.4. – 2 EW distributions, show how past measurements of EW – stellar mass trends and redshift evolution are selection biased, how our approach resolves the disagreement between observations and simulations of the cosmic sSFR evolution, and highlight our measured intrinsic EW(M,z) correlation. We find high EW (sSFR; bursty SFHs) Hα emitters are numerous and important contributors to cosmic star- formation activity at z > 1.5. Recent JWST studies (e.g., EIGER) find numerous high EW emitters at EoR with extreme ISM conditions and star-formation. Past studies also find EW correlates with ionizing photon production efficiency. Including our results, this suggests high EW emitters play a major role in cosmic SF and may be analogs of high-z ionizing sources at EoR. Finally, I will discuss how we can observe typical and high EW ELGs with Roman grism by using our EW(M,z) to predict number counts and range of EW and stellar mass.
Oscillations in solar Jets Observed with the SOT of Hinode: Viscous Effects during Reconnection
Creators: name: Tavabi, Ehsan
name: Koutchmy, Serge
Publisher: name: arXiv
Year: 2014
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Transverse oscillatory motions and recurrence behavior in the chromospheric jets observed by Hinode/SOT are studied. A comparison is considered with the behavior that was noticed in coronal X-ray jets observed by Hinode/XRT. A jet like bundle observed at the limb in Ca II H line appears to show a magnetic topology that is similar to X-ray jets (i.e., the Eiffel tower shape). The appearance of such magnetic topology is usually assumed to be caused by magnetic reconnection near a null point. Transverse motions of the jet axis are recorded but no clear evidence of twist is appearing from the highly processed movie. The aim is to investigate the dynamical behavior of an incompressible magnetic X-point occurring during the magnetic reconnection in the jet formation region. The viscous effect is specially considered in the closed line-tied magnetic X-shape nulls. We perform the MHD numerical simulation in 2-D by solving the visco-resistive MHD equations with the tracing of velocity and magnetic field. A qualitative agreement with Hinode observations is found for the oscillatory and non-oscillatory behaviors of the observed solar jets in both the chromosphere and the corona. Our results suggest that the viscous effect contributes to the excitation of the magnetic reconnection by generating oscillations that we observed at least inside this Ca II H line cool solar jet bundle.
description: making some corrections according to the proof of Journal
The influence of societal individualism on a century of tobacco use: modelling the prevalence of smoking
Creators: name: Lang, John C.
name: Abrams, Daniel M.
name: De Sterck, Hans
Publisher: name: arXiv
Year: 2014
Subjects: subject: Dynamical Systems (math.DS)
subject: Social and Information Networks (cs.SI)
subject: Physics and Society (physics.soc-ph)
subject: FOS: Mathematics
subject: FOS: Computer and information sciences
subject: FOS: Physical sciences
subject: 91D10 (Primary)

description: Smoking of tobacco is predicted to cause approximately six million deaths worldwide in 2014. Responding effectively to this epidemic requires a thorough understanding of how smoking behaviour is transmitted and modified. Here, we present a new mathematical model of the social dynamics that cause cigarette smoking to spread in a population. Our model predicts that more individualistic societies will show faster adoption and cessation of smoking. Evidence from a new century-long composite data set on smoking prevalence in 25 countries supports the model, with direct implications for public health interventions around the world. Our results suggest that differences in culture between societies can measurably affect the temporal dynamics of a social spreading process, and that these effects can be understood via a quantitative mathematical model matched to observations.
Modeling the Dispersion and Polarization Content of Gravitational Waves for Tests of General Relativity
Creators: name: Tso, Rhondale
name: Isi, Maximiliano
name: Chen, Yanbei
name: Stein, Leo
Publisher: name: arXiv
Year: 2016
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We propose a generic, phenomenological approach to modifying the dispersion of gravitational waves, independent of corrections to the generation mechanism. This model-independent approach encapsulates all previously proposed parametrizations, including Lorentz violation in the Standard-Model Extension, and provides a roadmap for additional theories. Furthermore, we present a general approach to include modulations to the gravitational-wave polarization content. The framework developed here can be implemented in existing data analysis pipelines for future gravitational-wave observation runs.
description: 4 pages, Presented at the Seventh Meeting on CPT and Lorentz Symmetry, Bloomington, Indiana, June 20-24, 2016
Entanglement and particle fluctuations of one-dimensional chiral topological insulators
Creators: name: Monkman, K.
name: Sirker, J.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: We consider the topological protection of entanglement and particle fluctuations for a general one-dimensional chiral topological insulator with winding number $\mathcal{I}$. We prove, in particular, that when the periodic system is divided spatially into two equal halves, the single-particle entanglement spectrum has $2|\mathcal{I}|$ protected eigenvalues at $1/2$. Therefore the number fluctuations are bounded from below by $ΔN^2\geq |\mathcal{I}|/2$ and the entanglement entropy by $S\geq 2|\mathcal{I}|\ln 2$. We note that our results are obtained by applying directly an index theorem to the microscopic model and do not rely on an equivalence to a continuum model or a bulk-boundary correspondence for a slow varying boundary.
description: 6 pages, published version
Characterization of JWST NIRCam PSFs and Implications for AGN+Host Image Decomposition
Creators: name: Zhuang, Mingyang
Publisher: name: Zenodo
Year: 2023
Subjects: Surveys of the flickering universe and galaxy formation

description: The correlations between masses of supermassive black holes and properties of their host galaxies suggest they may coevolve over cosmic time. The unprecedented resolution, sensitivity, and rest-frame optical coverage of the Near Infrared Camera (NIRCam) onboard JWST make it ideal to study the emission and morphology of host galaxies of high-redshift active galactic nuclei (AGNs). In this work, we perform a detailed characterization of NIRCam imaging PSFs in 8 filters: F070W, F115W, F150W, F200W, F277W, F356W, F444W, and F480M, using publicly available data. We find clear spatial PSF variations across the field-of-view of NIRCam, with maximum variations in PSF FWHM ranging from $\sim20$\% in F070W to $\sim5$\% in the F444W filter. Using mock AGN+host systems spanning a broad range of parameters, we investigate the reliability of host measurements from AGN+host decomposition with NIRCam imaging. We find that PSF mismatch has profound effects on the derived host properties. Our results suggest that there is an artificial offset between the centroids of the AGN and its host galaxy, which is larger in host galaxies with lower surface brightness.
Quantum Limits on the Capacity of Multispan Links with Phase-sensitive Amplification
Creators: name: Łukanowski, Karol
name: Banaszek, Konrad
name: Jarzyna, Marcin
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Long-distance fiber communication stands as a cornerstone of modern technology. One of the underlying principles, preventing signal levels from diminishing below the detectability threshold, is optical amplification. In particular, phase-sensitive amplifiers offer a promising solution as ideally they do not introduce any excess additive noise. Since such devices in principle operate at the quantum noise level, a natural question is whether one can further improve the capacity of amplified links using principles of quantum mechanics as it offers a much broader scope of signal modulations and detection schemes. We derive ultimate limits determined by the laws of quantum mechanics on the capacity of multispan links with phase sensitive amplification. We show that the quantum advantage over the standard approach based on optical quadrature detection is small and vanishes for long links.
description: 8 pages, 3 figures
Relative baryon-dark matter velocities in cosmological zoom simulations
Creators: name: Conaboy, Luke
name: Iliev, Ilian T.
name: Fialkov, Anastasia
name: Dixon, Keri L.
name: Sullivan, David
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: Supersonic relative motion between baryons and dark matter due to the decoupling of baryons from the primordial plasma after recombination affects the growth of the first small-scale structures. Large box sizes (greater than a few hundred Mpc) are required to sample the full range of scales pertinent to the relative velocity, while the effect of the relative velocity is strongest on small scales (less than a few hundred kpc). This separation of scales naturally lends itself to the use of `zoom' simulations, and here we present our methodology to self-consistently incorporate the relative velocity in zoom simulations, including its cumulative effect from recombination through to the start time of the simulation. We apply our methodology to a large-scale cosmological zoom simulation, finding that the inclusion of relative velocities suppresses the halo baryon fraction by $46$--$23$ per cent between $z=13.6$ and $11.2$, in qualitative agreement with previous works. In addition, we find that including the relative velocity delays the formation of star particles by $\sim 20 {~\rm Myr}$ Myr on average (of the order of the lifetime of a $\sim 9~{\rm M}_\odot$ Population III star) and suppresses the final stellar mass by as much as $79$ per cent at $z=11.2$.
description: 14 pages, 12 figures. Accepted for publication in MNRAS
One-step approach to ARPES from strongly correlated solids: a Mott-Hubbard system
Creators: name: Kuzian, R. O.
name: Krasovskii, E. E.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: An expression is derived for angle-resolved photocurrent from a semi-infinite correlated system. Within the sudden approximation, the photocurrent is proportional to the spectral function of a one-particle two-time retarded Green's function $\mathcal{G}$ of an operator that creates an electron in a special quantum state $χ$ localized at the surface. For a system described by a many-body single-band model we present an analytical expression that relates the Green's function $\mathcal{G}$ with the Green's function of an infinite crystal $G_{b,\mathbf{k}}(ω)$ in Wannier representation. The role of final states and of the crystal surface is analysed for a model Green's function of the infinite crystal with a three-peak spectral function typical of a Mott-Hubbard metal. The momentum dependence of both the quasiparticle pole position and the spectral weight of the incoherent band manifest themselves in the shape of the photocurrent energy distribution curve.
description: 18 pages 5 figures
Comment on Adler's "Does the Peres experiment using photons test for hyper-complex (quaternionic) quantum theories?"
Creators: name: Procopio, Lorenzo M.
name: Rozema, Lee A.
name: Dakić, Borivoje
name: Walther, Philip
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: In his recent article [arXiv:1604.04950], Adler questions the usefulness of the bound found in our experimental search for genuine effects of hyper-complex quantum mechanics [arXiv:1602.01624]. Our experiment was performed using a black-box (instrumentalist) approach to generalized probabilistic theories; therefore, it does not assume a priori any particular underlying mechanism. From that point of view our experimental results do indeed place meaningful bounds on possible effects of "post-quantum theories", including quaternionic quantum mechanics. In his article, Adler compares our experiment to non-relativistic and Möller formal scattering theory within quaternionic quantum mechanics. With a particular set of assumptions, he finds that quaternionic effects would likely not manifest themselves in general. Although these assumptions are justified in the non-relativistic case, a proper calculation for relativistic particles is still missing. Here, we provide a concrete relativistic example of Klein-Gordon scattering wherein the quaternionic effects persist. We note that when the Klein-Gordon equation is formulated using a Hamiltonian formalism it displays a so-called "indefinite metric", a characteristic feature of relativistic quantum wave equations. In Adler's example this is directly forbidden by his assumptions, and therefore our present example is not in contradiction to his work. In complex quantum mechanics this problem of an indefinite metric is solved in second quantization. Unfortunately, there is no known algorithm for canonical field quantization in quaternionic quantum mechanics.
description: 5 pages, one figure
Basins of Attraction for Chimera States
Creators: name: Martens, Erik A.
name: Panaggio, Mark J.
name: Abrams, Daniel M.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Pattern Formation and Solitons (nlin.PS)
subject: Dynamical Systems (math.DS)
subject: Adaptation and Self-Organizing Systems (nlin.AO)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: Chimera states---curious symmetry-broken states in systems of identical coupled oscillators---typically occur only for certain initial conditions. Here we analyze their basins of attraction in a simple system comprised of two populations. Using perturbative analysis and numerical simulation we evaluate asymptotic states and associated destination maps, and demonstrate that basins form a complex twisting structure in phase space. Understanding the basins' precise nature may help in the development of control methods to switch between chimera patterns, with possible technological and neural system applications.
description: Please see Ancillary files for the 4 supplementary videos including description (PDF)
The Milnor number of a hypersurface singularity in arbitrary characteristic
Creators: name: Hefez, Abramo
name: Rodrigues, João Helder Olmedo
name: Salomão, Rodrigo
Publisher: name: arXiv
Year: 2015
Subjects: subject: Algebraic Geometry (math.AG)
subject: FOS: Mathematics
subject: 14B05, 14H20, 14D06, 32S05

description: The Milnor number of an isolated hypersurface singularity, defined as the codimension $μ(f)$ of the ideal generated by the partial derivatives of a power series $f$ whose zeros represent locally the hypersurface, is an important topological invariant of the singularity over the complex numbers, but its meaning changes dramatically when the base field is arbitrary. It turns out that if the ground field is of positive characteristic, this number is not even invariant under contact equivalence of the local equation $f$. In this paper we study the variation of the Milnor number in the contact class of $f$, giving necessary and sufficient conditions for its invariance. We also relate, for an isolated singularity, the finiteness of $μ(f)$ to the smoothness of the generic fiber $f=s$. Finally, we prove that the Milnor number coincides with the conductor of a plane branch when the characteristic does not divide any of the minimal generators of its semigroup of values, showing in particular that this is a sufficient (but not necessary) condition for the invariance of the Milnor number in the whole equisingularity class of $f$.
description: 20 pages
Event-triggered Consensus Control of Heterogeneous Multi-agent Systems: Model- and Data-based Analysis
Creators: name: Wang, Xin
name: Sun, Jian
name: Wang, Gang
name: Chen, Jie
Publisher: name: arXiv
Year: 2022
Subjects: subject: Systems and Control (eess.SY)
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: This article deals with model- and data-based consensus control of heterogenous leader-following multi-agent systems (MASs) under an event-triggering transmission scheme. A dynamic periodic transmission protocol is developed to significantly alleviate the transmission frequency and computational burden, where the followers can interact locally with each other approaching the dynamics of the leader. Capitalizing on a discrete-time looped-functional, a model-based consensus condition for the closed-loop MASs is derived in form of linear matrix inequalities (LMIs), as well as a design method for obtaining the distributed controllers and event-triggering parameters. Upon collecting noise-corrupted state-input measurements during open-loop operation, a data-driven leader-following MAS representation is presented, and employed to solve the data-driven consensus control problem without requiring any knowledge of the agents' models. This result is then extended to the case of guaranteeing an $\mathcal{H}_{\infty}$ performance. A simulation example is finally given to corroborate the efficacy of the proposed distributed event-triggering scheme in cutting off data transmissions and the data-driven design method.
description: 13 pages, 6 figures. This draft was firstly submitted to IEEE Open Journal of Control Systems on April 30, 2022, but rejected on June 19, 2022. Later, on July 23, 2022, this paper was submitted to the journal SCIENCE CHINA information science
Experimental signature of initial quantum coherence on entropy production
Creators: name: Hernández-Gómez, S.
name: Gherardini, S.
name: Belenchia, A.
name: Trombettoni, A.
name: Paternostro, M.
name: Fabbri, N.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We report the experimental quantification of the contribution to non-equilibrium entropy production that stems from the quantum coherence content in the initial state of a qubit exposed to both coherent driving and dissipation. Our experimental demonstration builds on the exquisite experimental control of the spin state of a nitrogen-vacancy defect in diamond and is underpinned, theoretically, by the formulation of a generalized fluctuation theorem designed to track the effects of quantum coherence. Our results provide significant evidence of the possibility to pinpoint the genuinely quantum mechanical contributions to the thermodynamics of non-equilibrium quantum processes.
description: 5+5 pages, 4+2 figures, RevTeX4-2
On the Generalised Colouring Numbers of Graphs that Exclude a Fixed Minor
Creators: name: Heuvel, Jan van den
name: de Mendez, Patrice Ossona
name: Quiroz, Daniel
name: Rabinovich, Roman
name: Siebertz, Sebastian
Publisher: name: arXiv
Year: 2016
Subjects: subject: Combinatorics (math.CO)
subject: Discrete Mathematics (cs.DM)
subject: FOS: Mathematics
subject: FOS: Computer and information sciences
subject: 05C15 (Primary), 05C83, 05C12 (Secondary)

description: The generalised colouring numbers $\mathrm{col}_r(G)$ and $\mathrm{wcol}_r(G)$ were introduced by Kierstead and Yang as a generalisation of the usual colouring number, and have since then found important theoretical and algorithmic applications. In this paper, we dramatically improve upon the known upper bounds for generalised colouring numbers for graphs excluding a fixed minor, from the exponential bounds of Grohe et al. to a linear bound for the $r$-colouring number $\mathrm{col}_r$ and a polynomial bound for the weak $r$-colouring number $\mathrm{wcol}_r$. In particular, we show that if $G$ excludes $K_t$ as a minor, for some fixed $t\ge4$, then $\mathrm{col}_r(G)\le\binom{t-1}{2}\,(2r+1)$ and $\mathrm{wcol}_r(G)\le\binom{r+t-2}{t-2}\cdot(t-3)(2r+1)\in\mathcal{O}(r^{\,t-1})$. In the case of graphs $G$ of bounded genus $g$, we improve the bounds to $\mathrm{col}_r(G)\le(2g+3)(2r+1)$ (and even $\mathrm{col}_r(G)\le5r+1$ if $g=0$, i.e. if $G$ is planar) and $\mathrm{wcol}_r(G)\le\Bigl(2g+\binom{r+2}{2}\Bigr)\,(2r+1)$.
description: 21 pages, to appear in European Journal of Combinatorics
Anchoring Future Roman Deep Fields with COSMOS-Web: large scale structure to transients
Creators: name: Casey, Caitlin
Publisher: name: Zenodo
Year: 2023
Subjects: Surveys of the flickering universe and galaxy formation

description: I will present the utility of the COSMOS-Web JWST treasury program for future Roman Space Telescope deep field studies. As the largest JWST deep field at 0.54deg^2, 3 times larger than all other JWST deep fields combined, COSMOS-Web will serve as the ultimate calibration field for >degree-scale Roman surveys: for tuning of photometric redshifts for high-z galaxies, for mapping large scale structure, for weak lensing cosmological measurements, and for the detection of rare, high-redshift transients. I will discuss the unique niche of COSMOS-Web in working towards results in all of these areas, from reconstructing the large scale structure galaxy density field at 65. Lessons from COSMOS-Web will be crucial in the design and execution of large Roman surveys with similar scientific goals.
Model-Checking for Successor-Invariant First-Order Formulas on Graph Classes of Bounded Expansion
Creators: name: Heuvel, Jan van den
name: Kreutzer, Stephan
name: Pilipczuk, Michał
name: Quiroz, Daniel A.
name: Rabinovich, Roman
name: Siebertz, Sebastian
Publisher: name: arXiv
Year: 2017
Subjects: subject: Logic in Computer Science (cs.LO)
subject: FOS: Computer and information sciences

description: A successor-invariant first-order formula is a formula that has access to an auxiliary successor relation on a structure's universe, but the model relation is independent of the particular interpretation of this relation. It is well known that successor-invariant formulas are more expressive on finite structures than plain first-order formulas without a successor relation. This naturally raises the question whether this increase in expressive power comes at an extra cost to solve the model-checking problem, that is, the problem to decide whether a given structure together with some (and hence every) successor relation is a model of a given formula. It was shown earlier that adding successor-invariance to first-order logic essentially comes at no extra cost for the model-checking problem on classes of finite structures whose underlying Gaifman graph is planar [Engelmann et al., 2012], excludes a fixed minor [Eickmeyer et al., 2013] or a fixed topological minor [Eickmeyer and Kawarabayashi, 2016; Kreutzer et al., 2016]. In this work we show that the model-checking problem for successor-invariant formulas is fixed-parameter tractable on any class of finite structures whose underlying Gaifman graphs form a class of bounded expansion. Our result generalises all earlier results and comes close to the best tractability results on nowhere dense classes of graphs currently known for plain first-order logic.
description: 20 pages, submitted to LICS 2017
SUBARU prime focus spectrograph: integration, testing and performance for the first spectrograph
Creators: name: Madec, F.
name: Fur, A. Le
name: Mignant, D. Le
name: Dohlen, K.
name: Barrette, R.
name: Belhadi, M.
name: Pascal, S.
name: Smee, S.
name: Gunn, J.
name: Merrer, J. Le
name: Lorred, M.
name: Jaquet, M.
name: Balard, P.
name: Blanchard, P.
name: Thao, W.
name: Roman, F.
name: Lapere, V.
name: Gabriel, JF
name: Loomis, C.
name: Golebiowski, M.
name: Hart, M.
name: Oliveira, L.
name: Oliveira, A.
name: Tamura, N.
name: Shimono, A.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: The Prime Focus Spectrograph (PFS) of the Subaru Measurement of Images and Redshifts (SuMIRe) project for Subaru telescope consists in four identical spectrographs fed by 600 fibers each. Each spectrograph is composed by an optical entrance unit that creates a collimated beam and distributes the light to three channels, two visibles and one near infrared. This paper presents the on-going effort for the tests & integration process for the first spectrograph channel: we have developed a detailed Assembly Integration and Test (AIT) plan, as well as the methods, detailed processes and I&T tools. We describe the tools we designed to assemble the parts and to test the performance of the spectrograph. We also report on the thermal acceptance tests we performed on the first visible camera unit. We also report on and discuss the technical difficulties that did appear during this integration phase. Finally, we detail the important logistic process that is require to transport the components from other country to Marseille.
Complete bounded $λ$-hypersurfaces in the weighted volume-preserving mean curvature flow
Creators: name: Zhu, Yecheng
name: Fang, Yi
name: Chen, Qing
Publisher: name: arXiv
Year: 2017
Subjects: subject: Differential Geometry (math.DG)
subject: FOS: Mathematics

description: In this paper, we study the complete bounded $λ$-hypersurfaces in weighted volume-preserving mean curvature flow. Firstly, we investigate the volume comparison theorem of complete bounded $λ$-hypersurfaces with $|A|\leqα$ and get some applications of the volume comparison theorem. Secondly, we consider the relation among $λ$, extrinsic radius $k$, intrinsic diameter $d$, and dimension $n$ of the complete $λ$-hypersurface, and we obtain some estimates for the intrinsic diameter and the extrinsic radius. At last, we get some topological properties of the bounded $λ$-hypersurface with some natural and general restrictions.
Flat bands and Dirac cones in breathing lattices
Creators: name: Essafi, Karim
name: Jaubert, L. D. C.
name: Udagawa, M.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: In breathing pyrochlores and kagomes, couplings between neighbouring tetrahedra and triangles are free to differ. Breathing lattices thus offer the possibility to explore a different facet of the rich physics of these systems. Here we consider nearest-neighbour classical Heisenberg interactions, both ferromagnetic and antiferromagnetic, and study how the anisotropy of breathing lattices modifies the mode spectrum of pyrochlore and kagome systems. The nature and degeneracy of the flat bands are shown to be preserved for any value of the anisotropy. These flat bands can coexist with Dirac nodes at the $Γ$ point when the model becomes particle-hole symmetric. We also derive the nature of the ground state for the breathing kagome lattice, which bears a spontaneous chirality when neighbouring triangles are alternatively ferromagnetic and antiferromagnetic.
description: submitted as a proceeding for HFM 2016
Pitfalls of exergy analysis
Creators: name: Vágner, Petr
name: Pavelka, Michal
name: Maršík, František
Publisher: name: arXiv
Year: 2016
Subjects: subject: Chemical Physics (physics.chem-ph)
subject: FOS: Physical sciences

description: The well-known Gouy-Stodola theorem states that a device produces maximum useful power when working reversibly, that is with no entropy production inside the device. This statement then leads to a method of thermodynamic optimization based on entropy production minimization. Exergy destruction (difference between exergy of fuel and exhausts) is also given by entropy production inside the device. Therefore, assessing efficiency of a device by exergy analysis is also based on the Gouy-Stodola theorem. However, assumptions that had led to the Gouy-Stodola theorem are not satisfied in several optimization scenarios, e.g. non-isothermal steady-state fuel cells, where both entropy production minimization and exergy analysis should be used with caution. We demonstrate, using non-equilibrium thermodynamics, a few cases where entropy production minimization and exergy analysis should not be applied.
description: Accepted to Journal of Non-equilibrium thermodynamics
Colouring exact distance graphs of chordal graphs
Creators: name: Quiroz, Daniel A.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Combinatorics (math.CO)
subject: FOS: Mathematics

description: For a graph $G=(V,E)$ and positive integer $p$, the exact distance-$p$ graph $G^{[\natural p]}$ is the graph with vertex set $V$ and with an edge between vertices $x$ and $y$ if and only if $x$ and $y$ have distance $p$. Recently, there has been an effort to obtain bounds on the chromatic number $χ(G^{[\natural p]})$ of exact distance-$p$ graphs for $G$ from certain classes of graphs. In particular, if a graph $G$ has tree-width $t$, it has been shown that $χ(G^{[\natural p]}) \in \mathcal{O}(p^{t-1})$ for odd $p$, and $χ(G^{[\natural p]}) \in \mathcal{O}(p^{t}Δ(G))$ for even $p$. We show that if $G$ is chordal and has tree-width $t$, then $χ(G^{[\natural p]}) \in \mathcal{O}(p\, t^2)$ for odd $p$, and $χ(G^{[\natural p]}) \in \mathcal{O}(p\, t^2 Δ(G))$ for even $p$. If we could show that for every graph $H$ of tree-width $t$ there is a chordal graph $G$ of tree-width $t$ which contains $H$ as an isometric subgraph (i.e., a distance preserving subgraph), then our results would extend to all graphs of tree-width $t$. While we cannot do this, we show that for every graph $H$ of genus $g$ there is a graph $G$ which is a triangulation of genus $g$ and contains $H$ as an isometric subgraph.
description: 11 pages, 2 figures. Versions 2 and 3 include minor changes, which arise from reviewers' comments
Another piece of the puzzle: the fast HI outflow in Mrk231
Creators: name: Morganti, Raffaella
name: Veilleux, Sylvain
name: Oosterloo, Tom
name: Teng, Stacy H.
name: Rupke, David
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present the detection, performed with the Westerbork Synthesis Radio Telescope (WSRT) and the Karl Jansky Very Large Array (VLA), of a fast HI 21-cm outflow in the ultra-luminous infrared galaxy Mrk 231. The outflow is observed as shallow HI absorption blueshifted ~1300 km/s with respect to the systemic velocity and located against the inner kpc of the radio source. The outflowing gas has an estimated column density between 5 and 15x10^18 Tspin cm^-2. We derive the Tspin to lie in the range 400-2000 K and the densities are n_HI~10-100 cm^-3. Our results confirm the multiphase nature of the outflow in Mrk231. Although effects of the interaction between the radio plasma and the surrounding medium cannot be ruled out, the energetics and the lack of a clear kpc-scale jet suggest that the most likely origin of the HI outflow is a wide-angle nuclear wind, as earlier proposed to explain the neutral outflow traced by NaI and molecular gas. Our results suggest that an HI component is present in fast outflows regardless of the acceleration mechanism (wind vs jet driven) and that it must be connected with common properties of the pre-interaction gas. Considering the observed similarity of their column densities, the HI outflow likely represents the inner part of the broad wind identified on larger scales in NaI. The mass outflow rate of the HI outflow does not appear to be as large as the one observed in molecular gas. These characteristics suggest that the HI may represent a short intermediate phase in the rapid cooling of the gas. We also obtained deeper continuum images than previously available. At the resolution of ~1arcsec we do not see a kpc-scale jet. Instead, we detect a plateau of emission, likely due to star formation, surrounding the bright nuclear region. We also detect a poorly collimated bridge which may represent the channel feeding the southern lobe.
description: Accepted for publication in Astronomy & Astrophysics, 11 pages, 9 figures
Parametric amplification of light in a cavity with a moving dielectric membrane: Landau-Zener problem for the Maxwell field
Creators: name: Hasan, F.
name: O'Dell, D. H. J.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We perform a theoretical investigation into the classical and quantum dynamics of an optical field in a cavity containing a moving membrane ("membrane-in-the-middle" set-up). Our approach is based on the Maxwell wave equation, and complements previous studies based on an effective Hamiltonian. The analysis shows that for slowly moving and weakly reflective membranes the dynamics can be approximated by unitary, first-order-in-time evolution given by an effective Schrödinger-like equation with a Hamiltonian that does not depend on the membrane speed. This approximate theory is the one typically adopted in cavity optomechanics and we develop a criterion for its validity. However, in more general situations the full second-order wave equation predicts light dynamics which do not conserve energy, giving rise to parametric amplification (or reduction) that is forbidden under first order dynamics and can be considered to be the classical counterpart of the dynamical Casimir effect. The case of a membrane moving at constant velocity can be mapped onto the Landau-Zener problem but with additional terms responsible for field amplification. Furthermore, the nature of the adiabatic regime is rather different from the ordinary Schrödinger case, since mode amplitudes need not be constant even when there are no transitions between them. The Landau-Zener problem for a field is therefore richer than in the standard single-particle case. We use the work-energy theorem applied to the radiation pressure on the membrane as a self-consistency check for our solutions of the wave equation and as a tool to gain an intuitive understanding of energy pumped into/out of the light field by the motion of the membrane.
description: 27 pages, 15 figures
Temperature effects in the band structure of topological insulators
Creators: name: Monserrat, Bartomeu
name: Vanderbilt, David
Publisher: name: arXiv
Year: 2016
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We study the effects of temperature on the band structure of the Bi$_2$Se$_3$ family of topological insulators using first-principles methods. Increasing temperature drives these materials towards the normal state, with similar contributions from thermal expansion and from electron-phonon coupling. The band gap changes with temperature reach $0.3$ eV at $600$ K, of similar size to the changes caused by electron correlation. Our results suggest that temperature-induced topological phase transitions should be observable near critical points of other external parameters.
description: 5 pages, 3 figures
Temporal View Synthesis of Dynamic Scenes through 3D Object Motion Estimation with Multi-Plane Images
Creators: name: Somraj, Nagabhushan
name: Sancheti, Pranali
name: Soundararajan, Rajiv
Publisher: name: arXiv
Year: 2022
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: The challenge of graphically rendering high frame-rate videos on low compute devices can be addressed through periodic prediction of future frames to enhance the user experience in virtual reality applications. This is studied through the problem of temporal view synthesis (TVS), where the goal is to predict the next frames of a video given the previous frames and the head poses of the previous and the next frames. In this work, we consider the TVS of dynamic scenes in which both the user and objects are moving. We design a framework that decouples the motion into user and object motion to effectively use the available user motion while predicting the next frames. We predict the motion of objects by isolating and estimating the 3D object motion in the past frames and then extrapolating it. We employ multi-plane images (MPI) as a 3D representation of the scenes and model the object motion as the 3D displacement between the corresponding points in the MPI representation. In order to handle the sparsity in MPIs while estimating the motion, we incorporate partial convolutions and masked correlation layers to estimate corresponding points. The predicted object motion is then integrated with the given user or camera motion to generate the next frame. Using a disocclusion infilling module, we synthesize the regions uncovered due to the camera and object motion. We develop a new synthetic dataset for TVS of dynamic scenes consisting of 800 videos at full HD resolution. We show through experiments on our dataset and the MPI Sintel dataset that our model outperforms all the competing methods in the literature.
description: To appear in ISMAR 2022; Project website: https://nagabhushansn95.github.io/publications/2022/DeCOMPnet.html
title:   Effects of Forest Reclamation and Landscape Features on Avian Occupancy, Species Richness, and Abundance in Appalachia
Creators: name: Davenport, Rebecca
Publisher: name: University of Kentucky Libraries
Year: 2023
Subjects: classificationCode: 4.1
subject: FOS: Agriculture, forestry and fisheries

description: The Forestry Reclamation Approach (FRA) is a recently developed coal mining reclamation method that emphasizes best management practices in forestry, such as the planting of native trees and shrubs. Although the FRA is expected to benefit wildlife, no studies have empirically examined the effects of the FRA on avian species. My study aimed to identify which reclamation approaches and/or landscape features promote breeding songbirds, particularly mature forest avian guilds and species of conservation need. I conducted point count surveys in the Appalachian Mountains of eastern West Virginia and assessed differences in avian occupancy, species richness, and species abundance between four treatment types: 1) younger (< 9 years) FRA sites (YFRA), 2) older (9-20 years) FRA sites (OFRA), 3) non-FRA regenerated minelands (REGEN), and 4) unmined, mature forests (MAT). Younger FRA sites were positively associated with the disturbed (shrubland/forest edge) and generalist breeding habitat avian guilds, but negatively associated with the mature forest avian guild. Furthermore, I found that both FRA treatments supported numerous priority landbirds and species of greatest conservation need in the region. As the FRA becomes a more widespread and popular reclamation approach in Appalachia, this study will inform future management and reclamation efforts based on considerations for native birds.
description: © 2023 Rebecca N. Davenport
Variable-Length Coding with Cost Allowing Non-Vanishing Error Probability
Creators: name: Yagi, Hideki
name: Nomura, Ryo
Publisher: name: arXiv
Year: 2016
Subjects: subject: Information Theory (cs.IT)
subject: FOS: Computer and information sciences

description: We derive a general formula of the minimum achievable rate for fixed-to-variable length coding with a regular cost function by allowing the error probability up to a constant $\varepsilon$. For a fixed-to-variable length code, we call the set of source sequences that can be decoded without error the dominant set of source sequences. For any two regular cost functions, it is revealed that the dominant set of source sequences for a code attaining the minimum achievable rate with a cost function is also the dominant set for a code attaining the minimum achievable rate with the other cost function. We also give a general formula of the second-order minimum achievable rate.
description: 7 pages; extended version of a paper accepted by ISITA2016