cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
MILCANN : A neural network assessed tSZ map for galaxy cluster detection
Creators: name: Hurier, G.
name: Aghanim, N.
name: Douspis, M.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We present the first combination of thermal Sunyaev-Zel'dovich (tSZ) map with a multi-frequency quality assessment of the sky pixels based on Artificial Neural Networks (ANN) aiming at detecting tSZ sources from sub-millimeter observations of the sky by Planck. We construct an adapted full-sky ANN assessment on the fullsky and we present the construction of the resulting filtered and cleaned tSZ map, MILCANN. We show that this combination allows to significantly reduce the noise fluctuations and foreground residuals compared to standard tSZ maps. From the MILCANN map, we constructed the HAD tSZ source catalog that consists of 3969 sources with a purity of 90\%. Finally, We compare this catalog with ancillary catalogs and show that the galaxy-cluster candidates in the HAD catalog are essentially low-mass (down to $M_{500} = 10^{14}$ M$_\odot$) high-redshift (up to $z \leq 1$) galaxy cluster candidates.
description: The HAD catalog can be found in the download section of http://szcluster-db.ias.u-psud.fr
Late-time asymptotics for the wave equation on spherically symmetric, stationary spacetimes
Creators: name: Angelopoulos, Yannis
name: Aretakis, Stefanos
name: Gajic, Dejan
Publisher: name: arXiv
Year: 2016
Subjects: subject: Analysis of PDEs (math.AP)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: We derive precise late-time asymptotics for solutions to the wave equation on spherically symmetric, stationary and asymptotically flat spacetimes including as special cases the Schwarzschild and Reissner-Nordstrom families of black holes. We also obtain late-time asymptotics for the time derivatives of all orders and for the radiation field along null infinity. We show that the leading-order term in the asymptotic expansion is related to the existence of the conserved Newman-Penrose quantities on null infinity. As a corollary we obtain a characterization of all solutions which satisfy Price's polynomial law as a lower bound. Our analysis relies on physical space techniques and uses the vector field approach for almost-sharp decay estimates introduced in our companion paper. In the black hole case, our estimates hold in the domain of outer communications up to and including the event horizon. Our work is motivated by the stability problem for black hole exteriors and strong cosmic censorship for black hole interiors.
description: 3 figures
Fundamental bounds on MIMO antennas
Creators: name: Ehrenborg, Casimir
name: Gustafsson, Mats
Publisher: name: arXiv
Year: 2017
Subjects: subject: Classical Physics (physics.class-ph)
subject: Optimization and Control (math.OC)
subject: Applied Physics (physics.app-ph)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: Antenna current optimization is often used to analyze the optimal performance of antennas. Antenna performance can be quantified in e.g., minimum Q-factor and efficiency. The performance of MIMO antennas is more involved and, in general, a single parameter is not sufficient to quantify it. Here, the capacity of an idealized channel is used as the main performance quantity. An optimization problem in the current distribution for optimal capacity, measured in spectral efficiency, given a fixed Q-factor and efficiency is formulated as a semi-definite optimization problem. A model order reduction based on characteristic and energy modes is employed to improve the computational efficiency. The performance bound is illustrated by solving the optimization problem numerically for rectangular plates and spherical shells.
Homotopy Algebras of Differential (Super)forms in Three and Four Dimensions
Creators: name: Rocek, Martin
name: Zeitlin, Anton M.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Mathematical Physics (math-ph)
subject: High Energy Physics - Theory (hep-th)
subject: Quantum Algebra (math.QA)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: We consider various $A_{\infty}$-algebras of differential (super)forms, which are related to gauge theories and demonstrate explicitly how certain reformulations of gauge theories lead to the transfer of the corresponding $A_{\infty}$-structures. In $N=2$ 3D space we construct the homotopic counterpart of the de Rham complex, which is related to the superfield formulation of the $N=2$ Chern-Simons theory.
description: v2: 22 pages, minor revision
Signatures of hypermassive neutron star lifetimes on r-process nucleosynthesis in the disk ejecta from neutron star mergers
Creators: name: Lippuner, Jonas
name: Fernández, Rodrigo
name: Roberts, Luke F.
name: Foucart, Francois
name: Kasen, Daniel
name: Metzger, Brian D.
name: Ott, Christian D.
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We investigate the nucleosynthesis of heavy elements in the winds ejected by accretion disks formed in neutron star mergers. We compute the element formation in disk outflows from hypermassive neutron star (HMNS) remnants of variable lifetime, including the effect of angular momentum transport in the disk evolution. We employ long-term axisymmetric hydrodynamic disk simulations to model the ejecta, and compute r-process nucleosynthesis with tracer particles using a nuclear reaction network containing $\sim 8000$ species. We find that the previously known strong correlation between HMNS lifetime, ejected mass, and average electron fraction in the outflow is directly related to the amount of neutrino irradiation on the disk, which dominates mass ejection at early times in the form of a neutrino-driven wind. Production of lanthanides and actinides saturates at short HMNS lifetimes ($\lesssim 10$ ms), with additional ejecta contributing to a blue optical kilonova component for longer-lived HMNSs. We find good agreement between the abundances from the disk outflow alone and the solar r-process distribution only for short HMNS lifetimes ($\lesssim 10$ ms). For longer lifetimes, the rare-earth and third r-process peaks are significantly under-produced compared to the solar pattern, requiring additional contributions from the dynamical ejecta. The nucleosynthesis signature from a spinning black hole (BH) can only overlap with that from a HMNS of moderate lifetime ($\lesssim 60$ ms). Finally, we show that angular momentum transport not only contributes with a late-time outflow component, but that it also enhances the neutrino-driven component by moving material to shallower regions of the gravitational potential, in addition to providing additional heating.
description: 18 pages, 11 figures, published version with small changes
Labelled network subgraphs reveal stylistic subtleties in written texts
Creators: name: Marinho, Vanessa Q.
name: Hirst, Graeme
name: Amancio, Diego R.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Computation and Language (cs.CL)
subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: FOS: Computer and information sciences
subject: FOS: Physical sciences

description: The vast amount of data and increase of computational capacity have allowed the analysis of texts from several perspectives, including the representation of texts as complex networks. Nodes of the network represent the words, and edges represent some relationship, usually word co-occurrence. Even though networked representations have been applied to study some tasks, such approaches are not usually combined with traditional models relying upon statistical paradigms. Because networked models are able to grasp textual patterns, we devised a hybrid classifier, called labelled subgraphs, that combines the frequency of common words with small structures found in the topology of the network, known as motifs. Our approach is illustrated in two contexts, authorship attribution and translationese identification. In the former, a set of novels written by different authors is analyzed. To identify translationese, texts from the Canadian Hansard and the European parliament were classified as to original and translated instances. Our results suggest that labelled subgraphs are able to represent texts and it should be further explored in other tasks, such as the analysis of text complexity, language proficiency, and machine translation.
description: To appear in Journal of Complex Networks (JCN cnx047). The paper is available at https://tinyurl.com/y922r6pw
Validity of Clusters Produced By kernel-$k$-means With Kernel-Trick
Creators: name: Kłopotek, Mieczysław A.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Machine Learning (cs.LG)
subject: Machine Learning (stat.ML)
subject: FOS: Computer and information sciences

description: This paper corrects the proof of the Theorem 2 from the Gower's paper \cite[page 5]{Gower:1982} as well as corrects the Theorem 7 from Gower's paper \cite{Gower:1986}. The first correction is needed in order to establish the existence of the kernel function used commonly in the kernel trick e.g. for $k$-means clustering algorithm, on the grounds of distance matrix. The correction encompasses the missing if-part proof and dropping unnecessary conditions. The second correction deals with transformation of the kernel matrix into a one embeddable in Euclidean space.
description: 27 pages
Determination of the density region of the symmetry energy probed by the $π^-/π^+$ ratio
Creators: name: Yong, Gao-Chan
name: Gao, Yuan
name: Wei, Gao-Feng
name: Guo, Ya-Fei
name: Zuo, Wei
Publisher: name: arXiv
Year: 2017
Subjects: subject: Nuclear Theory (nucl-th)
subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: The studies, from several independent methods, consistently show that $π^-/π^+$ ratio in the $^{132}$Sn+$^{124}$Sn reaction at 300 MeV/nucleon, which is being carried out at Radioactive Isotope Beam Facility (RIBF) in Japan, just probes the symmetry energy around saturation density.
description: 6 pages, 6 figures, accepted by Journal of Physics G: Nuclear and Particle Physics
A vector field approach to almost-sharp decay for the wave equation on spherically symmetric, stationary spacetimes
Creators: name: Angelopoulos, Yannis
name: Aretakis, Stefanos
name: Gajic, Dejan
Publisher: name: arXiv
Year: 2016
Subjects: subject: Analysis of PDEs (math.AP)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: We present a new vector field approach to almost-sharp decay for the wave equation on spherically symmetric, stationary and asymptotically flat spacetimes. Specifically, we derive a new hierarchy of higher-order weighted energy estimates by employing appropriate commutator vector fields. In cases where an integrated local energy decay estimate holds, like in the case of sub-extremal Reissner-Nordstrom black holes, this hierarchy leads to almost-sharp global energy and pointwise time-decay estimates with decay rates that go beyond those obtained by the traditional vector field method. Our estimates play a fundamental role in our companion paper where precise late-time asymptotics are obtained for linear scalar fields on such backgrounds.
description: 104 pages, 7 figures
Hermite-Hadamard, Hermite-Hadamard-Fejer, Dragomir-Agarwal and Pachpatte Type Inequalities for Convex Functions via Fractional Integrals
Creators: name: Ahmad, Bashir
name: Alsaedi, Ahmed
name: Kirane, Mokhtar
name: Torebek, Berikbol T.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Functional Analysis (math.FA)
subject: FOS: Mathematics
subject: 26D15, 39B62

description: The aim of this paper is to establish Hermite-Hadamard, Hermite-Hadamard-Fejér, Dragomir-Agarwal and Pachpatte type inequalities for new fractional integral operators with exponential kernel. These results allow us to obtain a new class of functional inequalities which generalizes known inequalities involving convex functions. Furthermore, the obtained results may act as a useful source of inspiration for future research in convex analysis and related optimization fields.
description: 14 pages, to appear in Journal of Computational and Applied Mathematics
A symmetry-adapted numerical scheme for SDEs
Creators: name: De Vecchi, Francesco C.
name: Romano, Andrea
name: Ugolini, Stefania
Publisher: name: arXiv
Year: 2017
Subjects: subject: Probability (math.PR)
subject: Numerical Analysis (math.NA)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 60H35, 58D19

description: We propose a geometric numerical analysis of SDEs admitting Lie symmetries which allows us to individuate a symmetry adapted coordinates system where the given SDE has notable invariant properties. An approximation scheme preserving the symmetry properties of the equation is introduced. Our algorithmic procedure is applied to the family of general linear SDEs for which two theoretical estimates of the numerical forward error are established.
description: A numerical example added
On the theoretical and methodological challenges of the temporal binding effect
Creators: name: Saad, Laura
Publisher: name: No Publisher Supplied
Year: 2023

description: Temporal binding (TB) is assumed to be an implicit measure of the sense of agency. The sense of agency can be defined as the feeling of control over our voluntary actions and their associated consequences. TB is defined as the perceived subjective compression of time between a voluntary action and its associated outcome. Though TB has been replicated numerous times and is widely considered to be an implicit measure of the sense of agency in both the theoretical and applied literature, there is still some debate regarding the underlying mechanism for the effect. In this dissertation, I carefully analyze the temporal binding literature and systematically investigate theoretical and methodological issues which are impeding progress in our understanding of this effect. Chapter 1 contains a critical review of the temporal binding literature, highlighting the theoretical and methodological issues present while laying the groundwork for the empirical and modeling work that follows. Chapter 2 investigates how two seemingly extraneous methodological choices in a typical temporal binding experiment impact the pattern of results in unexpected ways: the presence of practice trials and the range of values on a slider that are presented to a participant during recall. Chapter 3 adds empirical evidence to the growing literature suggesting a dissociation between verbal reports of the sense of agency and the temporal binding effect thereby questioning the theoretical relationship between temporal binding and the sense of agency. Chapter 4 reconceptualizes temporal binding tasks as memory tasks and details the successful implementation of a Bayesian rational memory model to data from two temporal binding data sets. These results provide some evidence to suggest memory is an alternative, or at the very least partial, explanation for the observed pattern of results at the aggregate level in temporal binding tasks. Chapter 5 details the revisualization and reanalysis of 10 temporal binding data sets which reveals a consistent pattern of variability in the empirical signature of the temporal binding effect at the individual level. These results are further bolstered by the successful implementation of a Bayes factor mixed method modeling approach which simulated participant true effects (accounting for sampling noise) from two temporal binding data sets and confirms that some individuals have true effects in the opposite of the theoretically predicted direction. The implications of these results are discussed. The dissertation concludes with recommendations for future research on temporal binding and the sense of agency, more broadly.
Strongly correlated and topological states in [111] grown transition metal oxide thin films and heterostructures
Creators: name: Chakhalian, Jak
name: Liu, Xiaoran
name: Fiete, Gregory A.
Publisher: name: AIP Publishing
Year: 2020
Subjects: [111]

description: We highlight recent advances in the theory, materials fabrication, and experimental characterization of strongly correlated and topologi- cal states in [111] oriented transition metal oxide thin films and heterostructures, which are notoriously difficult to realize compared to their [001] oriented counterparts. We focus on two classes of complex oxides, with the chemical formulas ABO3 and A2B2O7, where the B sites are occupied by an open-shell transition metal ion with a local moment and the A sites are typically a rare earth element. The [111] oriented quasi-two-dimensional lattices derived from these parent compound lattices can exhibit peculiar geometries and symme- tries, namely, a buckled honeycomb lattice, as well as kagome and triangular lattices. These lattice motifs form the basis for emergent strongly correlated and topological states expressed in exotic magnetism, various forms of orbital ordering, topological insulators, topo- logical semimetals, quantum anomalous Hall insulators, and quantum spin liquids. For transition metal ions with high atomic number, spin–orbit coupling plays a significant role and may give rise to additional topological features in the electronic band structure and in the spectrum of magnetic excitations. We conclude this perspective by articulating open challenges and opportunities in this actively developing field.
Experimental Comparison of Probabilistic Shaping Methods for Unrepeated Fiber Transmission
Creators: name: Renner, Julian
name: Fehenberger, Tobias
name: Yankov, Metodi P.
name: Da Ros, Francesco
name: Forchhammer, Søren
name: Böcherer, Georg
name: Hanik, Norbert
Publisher: name: arXiv
Year: 2017
Subjects: subject: Information Theory (cs.IT)
subject: FOS: Computer and information sciences

description: This paper studies the impact of probabilistic shaping on effective signal-to-noise ratios (SNRs) and achievable information rates (AIRs) in a back-to-back configuration and in unrepeated nonlinear fiber transmissions. For back-to-back, various shaped quadrature amplitude modulation (QAM) distributions are found to have the same implementation penalty as uniform input. By demonstrating in transmission experiments that shaped QAM input leads to lower effective SNR than uniform input at a fixed average launch power, we experimentally confirm that shaping enhances the fiber nonlinearities. However, shaping is ultimately found to increase the AIR, which is the most relevant figure of merit as it is directly related to spectral efficiency. In a detailed study of these shaping gains for the nonlinear fiber channel, four strategies for optimizing QAM input distributions are evaluated and experimentally compared in wavelength division multiplexing (WDM) systems. The first shaping scheme generates a Maxwell-Boltzmann (MB) distribution based on a linear additive white Gaussian noise channel. The second strategy uses the Blahut-Arimoto algorithm to optimize an unconstrained QAM distribution for a split-step Fourier method based channel model. In the third and fourth approach, MB-shaped QAM and unconstrained QAM are optimized via the enhanced Gaussian noise (EGN) model. Although the absolute shaping gains are found to be relatively small, the relative improvements by EGN-optimized unconstrained distributions over linear AWGN optimized MB distributions are up to 59%. This general behavior is observed in 9-channel and fully loaded WDM experiments.
description: 9 pages, 7 figures, 7 tables
Impact of Sommerfeld enhancement on helium reionization via WIMP dark matter
Creators: name: Bandyopadhyay, Bidisha
name: Schleicher, Dominik R. G.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: Dark matter annihilation can have a strong impact on many astrophysical processes in the Universe. In the case of Sommerfeld-enhanced annihilation cross sections, the annihilation rates are enhanced at late times, thus enhancing the potential annihilation signatures. We here calculate the Sommerfeld-enhanced annihilation signatures during the epoch of helium reionization, the epoch where helium becomes fully ionized due to energetic photons. When considering the upper limits on the energy injection from the CMB, we find that the resulting abundance of He$^{++}$ becomes independent of the dark matter particle mass. The resulting enhancement compared to a standard scenario is thus 1-2 orders of magnitude higher. For realistic scenarios compatible with CMB constraints, there is no significant shift in the epoch of helium reionization, which is completed between redshifts $3$ and $4$. While it is thus difficult to disentangle dark matter annihilation from astrophysical contributions (active galactic nuclei), a potential detection of dark matter particles and its interactions using the Large Hadron Collider (LHC) would allow one to quantify the dark matter contribution.
description: 9 pages, 5 figures. Accepted fo publication in PRD
Electric field control of emergent electrodynamics in quantum spin ice
Creators: name: Lantagne-Hurtubise, Étienne
name: Bhattacharjee, Subhro
name: Moessner, Roderich
Publisher: name: arXiv
Year: 2017
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We study the coupling between conventional (Maxwell) and emergent electrodynamics in quantum spin ice, a 3+1-dimensional $U(1)$ quantum spin liquid. We find that a uniform electric field can be used to tune the properties of both the ground state and excitations of the spin liquid. In particular, it induces emergent birefringence, rendering the speed of the emergent light anisotropic and polarization-dependent. A sufficiently strong electric field triggers a quantum phase transition into new $U(1)$ quantum spin liquid phases which trap emergent electric $π$-fluxes. The flux patterns of these new phases depend on the direction of the electric field. Strikingly, some of the canonical pinch points in the spin structure factor, characteristic of classical spin ice, emerge near the phase transition, while they are absent in the quantum spin liquid phases. Estimating the electric field strength required, we find that this transition is potentially accessible experimentally. Finally, we propose a minimal mechanism by which an oscillating electric field can generate emergent radiation inside a quantum spin ice material with non-Kramers spin doublets.
description: 22 pages, 10 figures. Revised, published version
Simulations of the WFIRST Supernova Survey and Forecasts of Cosmological Constraints
Creators: name: Hounsell, R.
name: Scolnic, D.
name: Foley, R. J.
name: Kessler, R.
name: Miranda, V.
name: Avelino, A.
name: Bohlin, R. C.
name: Filippenko, A. V.
name: Frieman, J.
name: Jha, S. W.
name: Kelly, P. L.
name: Kirshner, R. P.
name: Mandel, K.
name: Rest, A.
name: Riess, A. G.
name: Rodney, S. A.
name: Strolger, L.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: The Wide Field InfraRed Survey Telescope (WFIRST) was the highest ranked large space-based mission of the 2010 New Worlds, New Horizons decadal survey. It is now a NASA mission in formulation with a planned launch in the mid-2020s. A primary mission objective is to precisely constrain the nature of dark energy through multiple probes, including Type Ia supernovae (SNe Ia). Here, we present the first realistic simulations of the WFIRST SN survey based on current hardware specifications and using open-source tools. We simulate SN light curves and spectra as viewed by the WFIRST wide-field channel (WFC) imager and integral-field channel (IFC) spectrometer, respectively. We examine 11 survey strategies with different time allocations between the WFC and IFC, two of which are based upon the strategy described by the WFIRST Science Definition Team, which measures SN distances exclusively from IFC data. We propagate statistical and, crucially, systematic uncertainties to predict the Dark Energy Task Force figure of merit (FoM) for each strategy. Of the strategies investigated, we find the most successful to be WFC-focused. However, further work in constraining systematics is required to fully optimize the use of the IFC. Even without improvements to other cosmological probes, the WFIRST SN survey has the potential to increase the FoM by more than an order of magnitude from the current values. Although the survey strategies presented here have not been fully optimized, these initial investigations are an important step in the development of the final hardware design and implementation of the WFIRST mission.
description: 50 pages, 18 figures, 14 tables, 3 appendices
Comments on Exchange Graphs in Cluster Algebras
Creators: name: Kim, Hyun Kyu
name: Yamazaki, Masahito
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Algebra (math.QA)
subject: High Energy Physics - Theory (hep-th)
subject: Rings and Algebras (math.RA)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 13F60

description: An important problem in the theory of cluster algebras is to compute the fundamental group of the exchange graph. A non-trivial closed loop in the exchange graph, for example, generates a non-trivial identity for the classical and quantum dilogarithm functions. An interesting conjecture, partly motivated by dilogarithm functions, is that this fundamental group is generated by closed loops of mutations involving only two of the cluster variables. We present examples and counterexamples for this naive conjecture, and then formulate a better version of the conjecture for acyclic seeds.
description: 18 pages, 4 figures; v2: journal version, an appendix added
First-principles insights into ultrashort laser spectroscopy of molecular nitrogen
Creators: name: Jangrouei, Mohammad Reza
name: Hashemifar, S. Javad
Publisher: name: arXiv
Year: 2017
Subjects: subject: Atomic and Molecular Clusters (physics.atm-clus)
subject: Chemical Physics (physics.chem-ph)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: In this research, we employ accurate time-dependent density functional calculations for ultrashort laser spectroscopy of nitrogen molecule. Laser pulses with different frequencies, intensities, and durations are applied to the molecule and the resulting photoelectron spectra are analyzed. It is argued that relative orientation of the molecule in the laser pulse significantly influence the orbital character of the emitted photoelectrons. Moreover, the duration of the laser pulse is also found to be very effective in controlling the orbital resolution and intensity of photoelectrons. Angular resolved distribution of photoelectrons are computed at different pulse frequencies and recording times. By exponential growth of the laser pulse intensity, the theoretical threshold of two photons absorption in nitrogen molecule is determined.
description: 7 pages, 6 figures, 2 tables
Context-Sensitive Super-Resolution for Fast Fetal Magnetic Resonance Imaging
Creators: name: McDonagh, Steven
name: Hou, Benjamin
name: Kamnitsas, Konstantinos
name: Oktay, Ozan
name: Alansary, Amir
name: Rutherford, Mary
name: Hajnal, Jo V.
name: Kainz, Bernhard
Publisher: name: arXiv
Year: 2017
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: 3D Magnetic Resonance Imaging (MRI) is often a trade-off between fast but low-resolution image acquisition and highly detailed but slow image acquisition. Fast imaging is required for targets that move to avoid motion artefacts. This is in particular difficult for fetal MRI. Spatially independent upsampling techniques, which are the state-of-the-art to address this problem, are error prone and disregard contextual information. In this paper we propose a context-sensitive upsampling method based on a residual convolutional neural network model that learns organ specific appearance and adopts semantically to input data allowing for the generation of high resolution images with sharp edges and fine scale detail. By making contextual decisions about appearance and shape, present in different parts of an image, we gain a maximum of structural detail at a similar contrast as provided by high-resolution data. We experiment on $145$ fetal scans and show that our approach yields an increased PSNR of $1.25$ $dB$ when applied to under-sampled fetal data \emph{cf.} baseline upsampling. Furthermore, our method yields an increased PSNR of $1.73$ $dB$ when utilizing under-sampled fetal data to perform brain volume reconstruction on motion corrupted captured data.
description: 11 pages, 6 figures, published in Proc MICCAI RAMBO'17 https://link.springer.com/chapter/10.1007/978-3-319-67564-0_12
Commensurating actions of birational groups and groups of pseudo-automorphisms
Creators: name: Cantat, Serge
name: de Cornulier, Yves
Publisher: name: arXiv
Year: 2017
Subjects: subject: Algebraic Geometry (math.AG)
subject: Group Theory (math.GR)
subject: Geometric Topology (math.GT)
subject: FOS: Mathematics
subject: 14E07 (Primary), 14J50, 20F65 (Secondary)

description: Pseudo-automorphisms are birational transformations acting as regular automorphisms in codimension 1. We import ideas from geometric group theory to prove that a group of birational transformations that satisfies a fixed point property on CAT(0) cubical complexes, for example a discrete countable group with Kazhdan Property (T), is birationally conjugate to a group acting by pseudo-automorphisms on some non-empty Zariski-open subset. We apply this argument to classify groups of birational transformations of surfaces with this fixed point property up to birational conjugacy.
description: V1 was a preliminary version. V1->V2: significantly expanded version with new sections. V2->V3: various corrections, and removal of the whole "categorical limit construction" section, now bypassed using divisorial valuations. 49 pages, 3 figures
Moderately Complex Paxos Made Simple: High-Level Executable Specification of Distributed Algorithms
Creators: name: Liu, Yanhong A.
name: Chand, Saksham
name: Stoller, Scott D.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Distributed, Parallel, and Cluster Computing (cs.DC)
subject: Programming Languages (cs.PL)
subject: FOS: Computer and information sciences

description: This paper describes the application of a high-level language and method in developing simpler specifications of more complex variants of the Paxos algorithm for distributed consensus. The specifications are for Multi-Paxos with preemption, replicated state machine, and reconfiguration and optimized with state reduction and failure detection. The language is DistAlgo. The key is to express complex control flows and synchronization conditions precisely at a high level, using nondeterministic waits and message-history queries. We obtain complete executable specifications that are almost completely declarative---updating only a number for the protocol round besides the sets of messages sent and received. We show the following results: 1.English and pseudocode descriptions of distributed algorithms can be captured completely and precisely at a high level, without adding, removing, or reformulating algorithm details to fit lower-level, more abstract, or less direct languages. 2.We created higher-level control flows and synchronization conditions than all previous specifications, and obtained specifications that are much simpler and smaller, even matching or smaller than abstract specifications that omit many algorithm details. 3.The simpler specifications led us to easily discover useless replies, unnecessary delays, and liveness violations (if messages can be lost) in previous published specifications, by just following the simplified algorithm flows. 4.The resulting specifications can be executed directly, and we can express optimizations cleanly, yielding drastic performance improvement over naive execution and facilitating a general method for merging processes. 5.We systematically translated the resulting specifications into TLA+ and developed machine-checked safety proofs, which also allowed us to detect and fix a subtle safety violation in an earlier unpublished specification.
Simple atomic quantum memory suitable for semiconductor quantum dot single photons
Creators: name: Wolters, Janik
name: Buser, Gianni
name: Horsley, Andrew
name: Beguin, Lucas
name: Jöckel, Andreas
name: Jahn, Jan-Philipp
name: Warburton, Richard J.
name: Treutlein, Philipp
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Quantum memories matched to single photon sources will form an important cornerstone of future quantum network technology. We demonstrate such a memory in warm Rb vapor with on-demand storage and retrieval, based on electromagnetically induced transparency. With an acceptance bandwidth of $δf$ = 0.66~GHz the memory is suitable for single photons emitted by semiconductor quantum dots. In this regime, vapor cell memories offer an excellent compromise between storage efficiency, storage time, noise level, and experimental complexity, and atomic collisions have negligible influence on the optical coherences. Operation of the memory is demonstrated using attenuated laser pulses on the single photon level. For 50 ns storage time we measure $η_{\textrm{e2e}}^{\textrm{50ns}} = 3.4(3)\%$ \emph{end-to-end efficiency} of the fiber-coupled memory, with an \emph{total intrinsic efficiency} $η_{\textrm{int}} = 17(3)\%$. Straightforward technological improvements can boost the end-to-end-efficiency to $η_{\textrm{e2e}} \approx 35\%$; beyond that increasing the optical depth and exploiting the Zeeman substructure of the atoms will allow such a memory to approach near unity efficiency. In the present memory, the unconditional readout noise level of $9\cdot 10^{-3}$ photons is dominated by atomic fluorescence, and for input pulses containing on average $μ_{1}=0.27(4)$ photons the signal to noise level would be unity.
Crisis? What Crisis? Cap. 3. Intimidades, subjetividades y otras afinidades electivas (libro de sala)
Creators: name: Salas Lamamié de Clairac, Ramón
name: Lemes Lemes, Moneiba
Publisher: name: TEA Tenerife Espacio de las Artes
Year: 2019
Subjects: Contemporary Art
Aesthetics
Theory of Art
Fine Arts
Art of the Canary Islands
subjectivity
representation
identity
painting
arte contemporaneo
estética
teoría del arte
bellas artes
arte canario
subjetividad
representación
identidad
pintura

description: Libro de Sala de la exposición Crisis? What Crisis? Cap. 3. Intimidades, subjetividades y otras afinidades electivas, que tuvo lugar en TEA Tenerife Espacio de las Artes entre el 24 de mayo y el 13 de octubre de 2019.
Bayesian GAN
Creators: name: Saatchi, Yunus
name: Wilson, Andrew Gordon
Publisher: name: arXiv
Year: 2017
Subjects: subject: Machine Learning (stat.ML)
subject: Artificial Intelligence (cs.AI)
subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Generative adversarial networks (GANs) can implicitly learn rich distributions over images, audio, and data which are hard to model with an explicit likelihood. We present a practical Bayesian formulation for unsupervised and semi-supervised learning with GANs. Within this framework, we use stochastic gradient Hamiltonian Monte Carlo to marginalize the weights of the generator and discriminator networks. The resulting approach is straightforward and obtains good performance without any standard interventions such as feature matching, or mini-batch discrimination. By exploring an expressive posterior over the parameters of the generator, the Bayesian GAN avoids mode-collapse, produces interpretable and diverse candidate samples, and provides state-of-the-art quantitative results for semi-supervised learning on benchmarks including SVHN, CelebA, and CIFAR-10, outperforming DCGAN, Wasserstein GANs, and DCGAN ensembles.
description: Updated to the version that appears at Advances in Neural Information Processing Systems 30 (NIPS), 2017
Heavy quarks within the electroweak multiplet
Creators: name: Besprosvany, J.
name: Romero, R.
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Standard-model fields and their associated electroweak Lagrangian are equivalently expressed in a shared spin basis. The scalar-vector terms are written with scalar-operator components acting on quark-doublet elements, and shown to be parametrization-invariant. Such terms, and the t- and b-quark Yukawa terms are linked by the identification of the common mass-generating Higgs operating upon the other fields, after acquiring a vacuum expectation value $v$. Thus, the customary vector masses are related to the fermions', fixing the t-quark mass $m_t$ with the relation $m^2_t+m^2_b=v^2/2$ either for maximal hierarchy, or given the b-quark mass $m_b$, implying $m_t \simeq 173.9$ GeV, for $v=246$ GeV. A sum rule is derived for all quark masses that generalizes this restriction. An interpretation follows that electroweak bosons and heavy quarks belong in a multiplet.
description: Extended Article. 54 pages, 2 Figures, 5 Tables, 27 References, 2 Appendices
How to categorify the ring of integers localized at two
Creators: name: Khovanov, Mikhail
name: Tian, Yin
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Algebra (math.QA)
subject: K-Theory and Homology (math.KT)
subject: Representation Theory (math.RT)
subject: FOS: Mathematics
subject: 16E20, 18D10, 16E35

description: We construct a triangulated monoidal Karoubi closed category with the Grothendieck ring, naturally isomorphic to the ring of integers localized at two.
description: 49 pages, 21 figures, final version
Near-horizon BMS symmetries as fluid symmetries
Creators: name: Penna, Robert F.
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: The Bondi-van der Burg-Metzner-Sachs (BMS) group is the asymptotic symmetry group of asymptotically flat gravity. Recently, Donnay et al. have derived an analogous symmetry group acting on black hole event horizons. For a certain choice of boundary conditions, it is a semidirect product of ${\rm Diff}(S^2)$, the smooth diffeomorphisms of the two-sphere, acting on $C^\infty(S^2)$, the smooth functions on the two-sphere. We observe that the same group appears in fluid dynamics as symmetries of the compressible Euler equations. We relate these two realizations of ${\rm Diff}(S^2)\ltimes C^\infty(S^2)$ using the black hole membrane paradigm. We show that the Lie-Poisson brackets of membrane paradigm fluid charges reproduce the near-horizon BMS algebra. The perspective presented here may be useful for understanding the BMS algebra at null infinity.
description: 18 pages, 3 figures
A comparison of Hake's g and Cohen's d for analyzing gains on concept inventories
Creators: name: Nissen, Jayson M.
name: Talbot, Robert M.
name: Thompson, Amreen Nasim
name: Van Dusen, Ben
Publisher: name: arXiv
Year: 2016
Subjects: subject: Physics Education (physics.ed-ph)
subject: FOS: Physical sciences

description: Measuring student learning is a complicated but necessary task for understanding the effectiveness of instruction and issues of equity in college STEM courses. Our investigation focused on the implications on claims about student learning that result from choosing between one of two commonly used methods for analyzing shifts in concept inventories. The methods are: Hake's gain (g), which is the most common method used in physics education research and other discipline based education research fields, and Cohen's d, which is broadly used in education research and many other fields. Data for the analyses came from the Learning Assistant Supported Student Outcomes (LASSO) database and included test scores from 4,551 students on physics, chemistry, biology, and math concept inventories from 89 courses at 17 institutions from across the United States. We compared the two methods across all of the concept inventories. The results showed that the two methods led to different inferences about student learning and equity due to g being biased in favor of high pretest populations. Recommendations for the analysis and reporting of findings on student learning data are included.
Combinatorial n-fold Integer Programming and Applications
Creators: name: Knop, Dušan
name: Koutecký, Martin
name: Mnich, Matthias
Publisher: name: arXiv
Year: 2017
Subjects: subject: Data Structures and Algorithms (cs.DS)
subject: FOS: Computer and information sciences
subject: F.2.2

description: Many fundamental NP-hard problems can be formulated as integer linear programs (ILPs). A famous algorithm by Lenstra solves ILPs in time that is exponential only in the dimension of the program, and polynomial in the size of the ILP. That algorithm became a ubiquitous tool in the design of fixed-parameter algorithms for NP-hard problems, where one wishes to isolate the hardness of a problemby some parameter. However, in many cases using Lenstra's algorithm has two drawbacks: First, the run time of the resulting algorithms is often doubly-exponential in the parameter, and second, an ILP formulation in small dimension cannot easily express problems involving many different costs. Inspired by the work of Hemmecke, Onn and Romanchuk [Math. Prog. 2013], we develop a single-exponential algorithm for so-called combinatorial n-fold integer programs, which are remarkably similar to prior ILP formulations for various problems, but unlike them, also allow variable dimension. We then apply our algorithm to a few representative problems like Closest String, Swap Bribery, Weighted Set Multicover, and obtain exponential speedups in the dependence on the respective parameters, the input size, or both. Unlike Lenstra's algorithm, which is essentially a bounded search tree algorithm, our result uses the technique of augmenting steps. At its heart is a deep result stating that in combinatorial n-fold IPs, existence of an augmenting step implies existence of a \local" augmenting step, which can be found using dynamic programming. Our results provide an important insight into many problems by showing that they exhibit this phenomenon, and highlights the importance of augmentation techniques.
description: 245 pages, preliminary results were presented during ESA 2017
Shadowing, asymptotic shadowing and s-limit shadowing
Creators: name: Good, Chris
name: Oprocha, Piotr
name: Puljiz, Mate
Publisher: name: arXiv
Year: 2017
Subjects: subject: Dynamical Systems (math.DS)
subject: FOS: Mathematics
subject: 37E05 (Primary), 37C50, 37B10, 54H20, 26A18 (Secondary)

description: We study three notions of shadowing: classical shadowing, limit (or asymptotic) shadowing, and s-limit shadowing. We show that classical and s-limit shadowing coincide for tent maps and, more generally, for piecewise linear interval maps with constant slopes, and are further equivalent to the linking property introduced by Chen in 1991. We also construct a system which exhibits shadowing but not limit shadowing, and we study how shadowing properties transfer to maximal transitive subsystems and inverse limits (sometimes called natural extensions). Where practicable, we show that our results are best possible by means of examples.
description: 28 pages, 4 figures
Orthogonal polynomials derived from the tridiagonal representation approach
Creators: name: Alhaidari, A. D.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Mathematical Physics (math-ph)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The tridiagonal representation approach is an algebraic method for solving second order differential wave equations. Using this approach in the solution of quantum mechanical problems, we encounter two new classes of orthogonal polynomials whose properties give the structure and dynamics of the corresponding physical system. For a certain range of parameters, one of these polynomials has a mix of continuous and discrete spectra making it suitable for describing physical systems with both scattering and bound states. In this work, we define these polynomials by their recursion relations and highlight some of their properties using numerical means. Due to the prime significance of these polynomials in physics, we hope that our short expose will encourage experts in the field of orthogonal polynomials to study them and derive their properties (weight functions, generating functions, asymptotics, orthogonality relations, zeros, etc.) analytically.
description: 11 pages, 3 tables, 4 figures
Random Lie-point symmetries of stochastic differential equations
Creators: name: Gaeta, Giuseppe
name: Spadaro, Francesco
Publisher: name: arXiv
Year: 2017
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: We study the invariance of stochastic differential equations under random diffeomorphisms, and establish the determining equations for random Lie-point symmetries of stochastic differential equations, both in Ito and in Stratonovich form. We also discuss relations with previous results in the literature.
description: In new version (November 2017) we have added an important ERRATUM. Due to a trivial mistake in a formula, several examples should be revised; more relevant, the qualitatove results of Section VIII turn out to be wrong, as discussed in the erratum. See also arXiv:1711.01999
The Dynamics of Wave-Particle Duality
Creators: name: Orefice, Adriano
name: Giovanelli, Raffaele
name: Ditto, Domenico
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Both classical and wave-mechanical monochromatic waves may be treated in terms of exact ray-trajectories (encoded in the structure itself of Helmholtz-like equations) whose mutual coupling is the one and only cause of any diffraction and interference process. In the case of Wave Mechanics, de Broglie's merging of Maupertuis's and Fermat's principles (see Section 3) provides, without resorting to the probability-based guidance-laws and flow-lines of the Bohmian theory, the simple law addressing particles along the Helmholtz rays of the relevant matter waves. The purpose of the present research was to derive the exact Hamiltonian ray-trajectory systems concerning, respectively, classical electromagnetic waves, non-relativistic matter waves and relativistic matter waves. We faced then, as a typical example, the numerical solution of non-relativistic wave-mechanical equation systems in a number of numerical applications, showing that each particle turns out to "dances a wave-mechanical dance" around its classical trajectory, to which it reduces when the ray-coupling is neglected. Our approach reaches the double goal of a clear insight into the mechanism of wave-particle duality and of a reasonably simple computability. We finally compared our exact dynamical approach, running as close as possible to Classical Mechanics, with the hydrodynamic Bohmian theory, based on fluid-like "guidance laws".
description: 20 pages, 11 figures. Improved text and abstract