cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Probing the LDA-1/2 method as a starting point for $G_0W_0$ calculations
Creators: name: Pela, Ronaldo Rodrigues
name: Werner, Ute
name: Nabok, Dmitrii
name: Draxl, Claudia
Publisher: name: arXiv
Year: 2016
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Employing the $G_0W_0$ approximation of Hedin's $GW$ approach one can obtain quasi-particle energies of extended systems and molecules with good accuracy. However, for many materials, semi-local exchange-correlation functionals are unsatisfactory starting points for $G_0W_0$ calculations. Hybrid functionals often improve upon them, but at a substantially higher computational cost. As an alternative, we suggest the LDA-1/2 method, which provides reasonable band gaps, without being computationally involved. In this work, we systematically compare 3 starting points for $G_0W_0$: LDA, PBE0, and LDA-1/2. A selection of solids is chosen for this benchmark: C, Si, SiC, AlP, LiF, MgO, Ne, Ar, GaN, GaAs, CdS, ZnS, and ZnO. We demonstrate that LDA-1/2 is a good starting point in most cases, reducing the mean absolute error of band gaps by 50% when compared to the other 2 functionals.
Solubility of FeSe2(cr) at 318 K in the presence of iron
Creators: name: Yoshida, Yasushi
name: Kitamura, Akira
name: Shibutani, Sanae
Publisher: name: Taylor & Francis
Year: 2023
Subjects: subject: Biochemistry
subject: Medicine
subject: Physiology
subject: FOS: Biological sciences
subject: Pharmacology
classificationCode: 59999
subject: Environmental Sciences not elsewhere classified
classificationCode: 39999
subject: Chemical Sciences not elsewhere classified
classificationCode: 69999
subject: Biological Sciences not elsewhere classified

description: The concentration of Se equilibrated with FeSe2(cr) was determined by solubility experiments under reducing conditions and 318 ± 1 K. Agreement between the solubility data obtained from the oversaturation and undersaturation directions suggested the attainment of equilibrium. X-ray diffraction analyses revealed the formation of the FeSe2(cr) phase only. The log10K0 values of −5.0 ± 1.4 and −14.9 ± 1.5 for the FeSe2(cr) solubility reactions of FeSe2(cr) ⇄ Fe2+ +0.5 Se42− + e− and FeSe2(cr) +2 H+ +2 e− ⇄ Fe2+ +2 HSe−, respectively were determined . Moreover, the selenium solubility in the presence of selenide and Fe under anoxic conditions was discussed with the results of our experiments and previous experimental work performed at 348 K. Under the experimental conditions corresponding to the typical pH and Eh of anoxic groundwater and equilibrium with stable FeSe2(cr), the Se solubilities were reduced and remained as constant values from 6.3 × 10−8 to 9.0 × 10−7 mol dm−3 over the pH range from 6.5 to 9.5, even in spite of the linear relationship between iron concentrations with pH. This indicated that Se was consumed before the formation of FeSe2(cr) and implied that consideration of reaction paths to equilibrium with FeSe2(cr) was necessary for an estimation of Se solubility for performance assessment in geological disposal system.
Multi-population minimal-time mean field games
Creators: name: Arjmand, Saeed Sadeghi
name: Mazanti, Guilherme
Publisher: name: arXiv
Year: 2021
Subjects: subject: Optimization and Control (math.OC)
subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics
subject: 49N80, 35Q89, 93C15, 35B40, 35A01

description: In this paper, we consider a mean field game model inspired by crowd motion in which several interacting populations evolving in $\mathbb R^d$ aim at reaching given target sets in minimal time. The movement of each agent is described by a control system depending on their position, the distribution of other agents in the same population, and the distribution of agents on other populations. Thus, interactions between agents occur through their dynamics. We consider in this paper the existence of Lagrangian equilibria to this mean field game, their asymptotic behavior, and their characterization as solutions of a mean field game system, under few regularity assumptions on agents' dynamics. In particular, the mean field game system is established without relying on semiconcavity properties of the value function.
The Kconfig Variability Framework as a Feature Model
Creators: name: Yaman, Kaan Berk
Publisher: name: Karlsruher Institut für Technologie (KIT)
Year: 2023
Subjects: Software variability
Feature-oriented programming (FOP)
Kconfig

description: Zur einfachen Handhabung von Softwarevariabilität werden oft externe Werkzeuge eingesetzt. Ein solches Werkzeug ist Kconfig, welches vom Linux-Kernel zur Erstellung von konkreten Softwarekonfigurationen benutzt wird. Kconfig arbeitet mit Textdateien, in denen die Variabilitätsstruktur des zugehörigen Softwareprojekts definiert wird. Diese Dateien werden oft als Kconfig-Dateien bezeichnet. Kconfig-Dateien können analysiert werden, um Probleme in der Variabilitätsstruktur festzustellen. Feature-orientierte Programmierung (FOP) wird auch zur besseren Handhabung von Softwarevariabilität eingesetzt. Die Variabilitätsstruktur eines Softwareprojekts wird im Umfang von FOP in einem sogenannten Feature-Modell dargestellt. Es gibt Werkzeuge, welche zur Analyse von Feature-Modellen verwendet werden können. Diese kann man jedoch nicht zur Analyse von Kconfig-Dateien nutzen, da bisher eine Transformation zwischen Kconfig-Dateien und Feature-Modellen fehlt. In dieser Arbeit stellen wir eine Methodik zur korrekten Transformation von Kconfig-Dateien in Feature-Modelle vor, sodass Werkzeuge zur Feature-Modell-Analyse auch auf Kconfig-Dateien angewandt werden können. Wir evaluieren die Korrektheit unserer Transformation mit automatischen und manuellen Vorgehen. Unsere Methodik kann ausgewählte Kconfig-Dateien mit nichttrivialer Struktur erfolgreich in semantisch äquivalente Feature-Modelle überführen.
Validation of LWR fuel depletion calculation module of reactor physics code system CBZ
Creators: name: Chiba, Go
name: Harada, Hiroki
Publisher: name: Taylor & Francis
Year: 2023
Subjects: subject: Biophysics
subject: Space Science
classificationCode: 29999
subject: Physical Sciences not elsewhere classified
subject: Medicine
subject: Microbiology
subject: FOS: Biological sciences
subject: Cell Biology
subject: Genetics
classificationCode: 39999
subject: Chemical Sciences not elsewhere classified
classificationCode: 69999
subject: Biological Sciences not elsewhere classified
classificationCode: 19999
subject: Mathematical Sciences not elsewhere classified
subject: Inorganic Chemistry
subject: FOS: Chemical sciences
classificationCode: 110309
subject: Infectious Diseases
subject: FOS: Health sciences
subject: Plant Biology
classificationCode: 60506
subject: Virology

description: This paper presents the results of validation calculations of the nuclear fuel depletion calculation module of the CBZ reactor physics code system, CBZ/Burner. Validation calculations were conducted using the post irradiation examination data obtained at Fukushima-Daini Unit 2 and at Takahama Unit 3. The nuclide number densities calculated with CBZ/Burner were compared with the measurement values, and generally good agreement was obtained. The sensitivity coefficients of the nuclide number densities with respect to nuclear data were calculated for all concerned nuclides with the depletion perturbation calculation capability of CBZ/Burner, and the nuclear data-induced uncertainties of the nuclide number densities were quantified. From the numerical results, we can conclude that the nuclear fuel depletion calculation module for LWR in the CBZ code system was successfully validated.
Deep learning-based photoacoustic imaging of vascular network through thick porous media
Creators: name: Gao, Ya
name: Xu, Wenyi
name: Chen, Yiming
name: Xie, Weiya
name: Cheng, Qian
Publisher: name: arXiv
Year: 2021
Subjects: subject: Medical Physics (physics.med-ph)
subject: FOS: Physical sciences

description: Photoacoustic imaging (PAI) is a promising approach to realize in vivo transcranial cerebral vascular imaging. However, the strong attenuation and distortion of the photoacoustic wave caused by the thick porous skull greatly affect the imaging quality. In this study, we designed a convolutional neural network (CNN) with a U-Net architecture to extract the effective photoacoustic information hidden in the speckle patterns; obtained vascular network images datasets under porous media through simulation and experiment, and trained the network weights respectively. The results show that the proposed neural network can learn the mapping relationship between the speckle pattern and the target; extract the photoacoustic signals of some vessels submerged in noise to reconstruct high-quality images with a sharp outline of the vessel and clean background. Compared with the traditional photoacoustic reconstruction method, the deep learning-based reconstruction algorithms can achieve better performance, the mean absolute error (MAE), Structural SIMilarity (SSIM) and peak signal-to-noise ratio (PSNR) of reconstructed images have been greatly improved. In conclusion, the proposed neural network can effectively extract valid information from highly blurred speckle patterns for the rapid reconstruction of target images, which offers promising applications in transcranial photoacoustic imaging.
description: 14 pages, 14 figures, 4 tables
The quenching time scale and quenching rate of galaxies
Creators: name: Lian, Jianhui
name: Yan, Renbin
name: Zhang, Kai
name: Kong, Xu
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The average star formation rate (SFR) in galaxies has been declining since redshift of 2. A fraction of galaxies quench and become quiescent. We constrain two key properties of the quenching process: the quenching time scale and the quenching rate among galaxies. We achieve this by analyzing the galaxy number density profile in NUV-u color space and the distribution in NUV-u v.s. u-i color-color diagram with a simple toy-model framework. We focus on galaxies in three mass bins between 10 to 10 and 10 to 10.6 solar mass. In the NUV-u v.s. u-i color-color diagram, the red u-i galaxies exhibit a different slope from the slope traced by the star-forming galaxies. This angled distribution and the number density profile of galaxies in NUV-u space strongly suggest that the decline of the SFR in galaxies has to accelerate before they turn quiescent. We model this color-color distribution with a two-phase exponential decline star formation history. The models with an e-folding time in the second phase (the quenching phase) of 0.5 Gyr best fit the data. We further use the NUV-u number density profile to constrain the quenching rate among star-forming galaxies as a function of mass. Adopting an e-folding time of 0.5 Gyr in the second phase (or the quenching phase), we found the quenching rate to be 19%/Gyr, 25%/Gyr and 33%/Gyr for the three mass bins. These are upper limits of quenching rate as the transition zone could also be populated by rejuvenated red-sequence galaxies.
description: 9 pages, 6 figures, accepted for publication in ApJ
Incompressible Energy Spectrum from Wave Turbulence
Creators: name: Filho, Marcos A. G. dos Santos
name: Santos, Francisco E. A. dos
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: Bose-Einstein condensates with their superfluidity property provide an interesting parallel to classical fluids. Due to the Kolmogorov spectrum of homogeneous turbulence the statistics of the incompressible velocity field is of great interest, but in superfluids obtaining quantities such as the statistics of the velocity field from the macroscopic wavefunction turns out be a complicated task; therefore, most of the work up to now has been numerical in nature. We made use of the Weak Wave Turbulence (WWT) theory, which provides the statistics of the macroscopic wavefunction, to obtain the statistics of the velocity field, which allowed us to produce a semi analytical procedure for extracting the incompressible energy spectrum in the WWT regime. This is done by introducing an auxiliary wavefunction that preserves the relevant statistical and hydrodynamical properties of the condensate but with a homogeneous density thus allowing for a simpler description of the velocity field.
description: 11 pages, 5 figures
Staggered Flux State in Two-Dimensional Hubbard Models
Creators: name: Yokoyama, Hisatoshi
name: Tamura, Shun
name: Ogata, Masao
Publisher: name: arXiv
Year: 2016
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: The stability and other properties of a staggered flux (SF) state or a correlated d-density wave state are studied for the Hubbard (t-t'-U) model on extended square lattices, as a low-lying state that competes with the d(x2-y2)-wave superconductivity (d-SC) and possibly causes the pseudogap phenomena in underdoped high-Tc cuprates and organic kappa-BEDT-TTF salts. In calculations, a variational Monte Carlo method is used. In the trial wave function, a configuration-dependent phase factor, which is vital to treat a current-carrying state for a large U/t, is introduced in addition to ordinary correlation factors. Varying U/t, t'/t, and the doping rate (delta) systematically, we show that the SF state becomes more stable than the normal state (projected Fermi sea) for a strongly correlated (U/t\gtrsim 5) and underdoped (delta\lesssim 0.16) area. The decrease in energy is sizable, particularly in the area where Mott physics prevails and the circular current (order parameter) is strongly suppressed. These features are consistent with those for the t-J model. The effect of the frustration t'/t plays a crucial role in preserving charge homogeneity and appropriately describing the behavior of hole- and electron-doped cuprates and kappa-BEDT-TTF salts. We argue that the SF state does not coexist with d-SC and is not a `normal state' from which d-SC arises. We also show that a spin current (flux or nematic) state is never stabilized in the same regime.
description: 21 pages, 33 figures, to be published in J. Phys. Soc. Jpn
Exploring and demonstrating the potential of Open Science for ocean sustainability (IQuOD online meeting)
Creators: name: Simoncelli, Simona
Publisher: name: Zenodo
Year: 2023

description: Blue-Cloud 2026 builds upon the pilot Blue-Cloud project which established a cyber platform, providing researchers: access to multi-disciplinary datasets from observations, analytical services, and computing facilities. Blue-Cloud 2026 aims at a further evolution into a Federated EU Ecosystem to deliver FAIR & Open data, analytical services, instrumental for deepening research of oceans, EU seas, coastal & inland waters. Blue-Cloud 2026 develops a thematic marine extension to EOSC for open web-based science, & serves needs of the EU Blue Economy, Marine Environment and Marine Knowledge agendas. Presented at the IQuOD online meeting on 6 July 2023
Independence equivalence classes of cycles
Creators: name: Ng, Boon Leong
Publisher: name: arXiv
Year: 2021
Subjects: subject: Combinatorics (math.CO)
subject: FOS: Mathematics

description: The independence equivalence class of a graph $G$ is the set of graphs that have the same independence polynomial as $G$. Beaton, Brown and Cameron (arXiv:1810.05317) found the independence equivalence classes of even cycles, and raised the problem of finding the independence equivalence class of odd cycles. The problem is completely solved in this paper.
Theory of sorption and electronic transport in amorphous polymers and single molecules
Creators: name: Jay, Michael
Publisher: name: Lancaster University
Year: 2020

description: This thesis describes a series of studies of the energetics, structure, sorption and electronic transport of polymers and single molecules at the nanoscale. The first of these relates to hypercrosslinked porous polymers, which are of technological and commercial interest for their ability to efficiently absorb molecules in a wide range of contexts from pharmaceuticals to gas storage. I model a family of polymers synthesised by collaborators at the University of Strathclyde, which show very high uptake of polyaromatic hydrocarbon (PAH) molecules from solution and could potentially be used as a filtration material to remove these molecules from vehicle lubrication oils, where they are responsible for the build up of soot and the long term degradation of both oil and engine. Density functional theory calculations identified the structural units of the polymers contributing most to sorption, and the relative binding strengths of several PAHs which correspond to the experimental trends. Molecular dynamics simulations of the polymer pores with PAH molecules in a heptane solution highlighted the significance of polymer flexibility and pore size in the sorption process. In the second I analyse the conductance of the first organically synthesized sp-sp3 hybridized porous carbon, OSPC-1. This new carbon shows electron conductivity, high porosity, the highest uptake of lithium ions of any carbon material to-date, and the ability to inhibit dangerous lithium dendrite formation. It therefore has potential as an anode material for lithium-ion batteries with high capacity, excellent rate capability, long cycle life, and potential for improved safety performance. Detailed simulation of the variation of the conductivity of this amorphous material versus length using a tight binding methodology showed that the measured conductance is consistent with an inelastic scattering length of the size of an OPSC-1 fragment. The third project is in the field of molecular electronics, where a crucial area of research aims to identify molecular anchor groups to bind molecules to electrodes. This study presents a series of oligo(phenylene-ethynylene) wires with one tetrapodal anchor and a phenyl or pyridyl head group. The new anchors are designed to bind strongly to gold surfaces without disrupting the conductance pathway of the wires. Density functional theory was used to simulate the structures of the molecules and the nature of their binding to the Au surface. Quantum transport calculations provided insight into the conductance pathway through the molecules and confirmed the decoupling between surface binding and electronic coupling. This feature may enable the inclusion in junctions of a wider range of functional groups, in particular those with strong electronic coupling, but only weak physical binding.
Comprehensive Multi-Modal Interactions for Referring Image Segmentation
Creators: name: Jain, Kanishk
name: Gandhi, Vineet
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: We investigate Referring Image Segmentation (RIS), which outputs a segmentation map corresponding to the natural language description. Addressing RIS efficiently requires considering the interactions happening across visual and linguistic modalities and the interactions within each modality. Existing methods are limited because they either compute different forms of interactions sequentially (leading to error propagation) or ignore intramodal interactions. We address this limitation by performing all three interactions simultaneously through a Synchronous Multi-Modal Fusion Module (SFM). Moreover, to produce refined segmentation masks, we propose a novel Hierarchical Cross-Modal Aggregation Module (HCAM), where linguistic features facilitate the exchange of contextual information across the visual hierarchy. We present thorough ablation studies and validate our approach's performance on four benchmark datasets, showing considerable performance gains over the existing state-of-the-art (SOTA) methods.
description: Findings of ACL 2022
Landau's Nobel Prize in Physics
Creators: name: Larsson, Mats
name: Balatsky, A. V.
Publisher: name: arXiv
Year: 2016
Subjects: subject: History and Philosophy of Physics (physics.hist-ph)
subject: FOS: Physical sciences

description: Work of Lev Landau had a profound impact on the physics in 20th century. Landau had created the paradigms that had framed the conversations on the outstanding problems in physics for decades. He has laid the foundations for our understanding of quantum matter such as superfluidity, superconductivity and the theory of Fermi Liquid. Here we present sampled Nobel Archive data on the winning nomination that led to the Nobel Prize in Physics in 1962.
description: 10 pages, 3 figures, accepted Pis'ma v ZhETF, JEPT Letters
The Abundancy Index and Feebly Amicable Numbers
Creators: name: Bishop, Jamie
name: Bozarth, Abigail
name: Kuss, Rebekah
name: Peet, Benjamin
Publisher: name: arXiv
Year: 2021
Subjects: subject: Number Theory (math.NT)
subject: FOS: Mathematics
subject: 11A99

description: This research explores the sum of divisors - $σ(n)$ - and the abundancy index given by the function $\frac{σ(n)}{n}$. We give a generalization of amicable pairs - feebly amicable pairs (also known as harmonious pairs), that is $m,n$ such that $\frac{n}{σ(n)}+ \frac{m}{σ(m)}=1$. We first give some groundwork in introductory number theory, then the goal of the paper is to determine if all numbers are feebly amicable with at least one other number by using known results about the abundancy index. We establish that not all numbers are feebly amicable with at least one other number. We generate data using the R programming language and give some questions and conjectures.
description: 9 pages, 2 figures, changes made after referee's comments
The Goldman and Fock-Goncharov coordinates for convex projective structures on surfaces
Creators: name: Bonahon, Francis
name: Kim, Inkang
Publisher: name: arXiv
Year: 2016
Subjects: subject: Geometric Topology (math.GT)
subject: FOS: Mathematics
subject: 51M10, 57S25

description: Let P(S) be the space of convex projective structures on a surface S with negative Euler characteristic. Goldman and Bonahon-Dreyer constructed two different sets of global coordinates for P(S), both associated to a pair of pants decomposition of the surface S. The article explicitly describes the coordinate change between these two parametrizations. Most of the arguments are concentrated in the case where S is a pair of pants, in which case the Bonahon-Dreyer coordinates are actually due to Fock-Goncharov.
description: 12 pages. Version 2: Misprints corrected, and a couple of references added
Determination of the thickness and orientation of few-layer tungsten ditelluride using polarized Raman spectroscopy
Creators: name: Kim, Minjung
name: Han, Songhee
name: Kim, Jung Hwa
name: Lee, Jae-Ung
name: Lee, Zonghoon
name: Cheong, Hyeonsik
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Orthorhombic tungsten ditelluride (WTe2), with a distorted 1T structure, exhibits a large magnetoresistance that depends on the orientation, and its electrical characteristics changes rom semimetallic to insulating as the thickness decreases. Through polarized Raman spectroscopy in combination with transmission electron diffraction, we establish a reliable method to determine the thickness and crystallographic orientation of few-layer WTe2. The Raman spectrum shows a pronounced dependence on the polarization of the excitation laser. We found that the separation between two Raman peaks at ~90 cm-1 and at 80-86 cm-1, depending on thickness, is a reliable fingerprint for determination of the thickness. For determination of the crystallographic orientation, the polarization dependence of the A1 modes, measured with the 632.8-nm excitation, turns out to be the most reliable. We also discovered that the polarization behaviors of some of the Raman peaks depend on the excitation wavelength as well as thickness, indicating a close interplay between the band structure and anisotropic Raman scattering cross section.
description: 16 pages, 4 figures
On two problems of Carlitz and their generalizations
Creators: name: Baoulina, Ioulia N.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Number Theory (math.NT)
subject: FOS: Mathematics
subject: 11D79, 11G25, 11T24

description: Let $N_q$ be the number of solutions to the equation $$ (a_1^{}x_1^{m_1}+\dots+a_n^{}x_n^{m_n})^k=bx_1^{k_1}\cdots x_n^{k_n} $$ over the finite field $\mathbb F_q=\mathbb F_{p^s}$. Carlitz found formulas for~$N_q$ when $k_1=\dots=k_n=m_1=\dots=m_n=1$, $k=2$, $n=3$ or $4$, $p>2$; and when ${m_1=\dots=m_n=2}$, $k=k_1=\dots=k_n=1$, $n=3$ or $4$, $p>2$. In earlier papers, we studied the above equation with $k_1=\dots=k_n=1$ and obtained some generalizations of Carlitz's results. Recently, Pan, Zhao and Cao considered the case of arbitrary positive integers $k_1,\dots,k_n$ and proved the formula $N_q=q^{n-1}+(-1)^{n-1}$, provided that $\gcd(\sum_{j=1}^n (k_jm_1\cdots m_n/m_j)-km_1\cdots m_n,q-1)=1$. In this chapter, we determine $N_q$ explicitly in some other cases.
description: 8 pages, 2 tables
GTnum PERSEUS #InteractionHybridation - Interactions et hybridation
Creators: name: Fleck, Stéphanie
name: Massou, Luc
name: Serna, Audrey
Publisher: name: Zenodo
Year: 2023
Subjects: #GTnum
Hybridation
Interaction
Contexte scolaire
Hybridation présentiel/distanciel
Hybridation physique/numérique
Influences transformatives
DNE
Direction du numérique pour l'éducation

description: Le GTnum #InteractionHybridation: “Enseignement et apprentissage en situation(s) hybride(s): vers une réinvention de la forme scolaire?” cherche à cerner les différentes formes et interactions que sous-tend le terme “hybride” au sein de travaux issus de la recherche en interaction Humain-Machine, des terrains professionnels d’enseignement et de formation. Ce bulletin de veille introductif du GTnum #InteractionHybridation résume ses objectifs en lien avec les questions d'hybridation des interactions dans le contexte scolaire.
description: Les groupes thématiques numériques (GTnum) sont coordonnés par la Direction du numérique pour l'éducation du Ministère de l'Education nationale et de la Jeunesse. Les GTnum ont pour objectif de mettre à disposition des équipes éducatives, de façon accessible et ouverte, un état de la recherche sur quelques grandes thématiques relatives au numérique dans l'éducation. Financeur du projet:« Ministère de l'Éducation nationale et de la Jeunesse»
Improved sensing with a single qubit
Creators: name: Sekatski, P.
name: Skotiniotis, M.
name: Dür, W.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We consider quantum metrology with arbitrary prior knowledge of the parameter. We demonstrate that a single sensing two-level system can act as a virtual multi-level system that offers increased sensitivity in a Bayesian, single-shot, metrology scenario and that allows one to estimate (arbitrary) large parameter values by avoiding phase wraps. This is achieved by making use of additional degrees of freedom or auxiliary systems not participating in the sensing process. The joint system is manipulated by intermediate control operations in such a way that an effective Hamiltonian, with an arbitrary spectrum, is generated that mimics the spectrum of a multi-level system interacting with the field. We show how to use additional internal degrees of freedom of a single trapped ion to achieve a high-sensitivity magnetic field sensor for fields with arbitrary prior.
description: 8 pages (including appendix) plus 5 figures
Nitrogenous compounds in the Nueces River and Bay and the impact of a sewage treatment plant : the development of field instrumentation using ion selective electrodes
Creators: name: Seguin, Russell Joseph, 1957-
Publisher: name: The University of Texas at Austin
Year: 1996
Subjects: subject: Water quality
subject: Texas
subject: Nueces River
subject: Nueces Bay
subject: Sewage purification
subject: Nitrogen removal
subject: Nitrogen compounds
subject: Ion selective electrodes
subject: Water quality--Texas--Nueces River
subject: Water quality--Texas--Nueces Bay
subject: Sewage--Purification--Nitrogen removal
subject: Nitrogen compounds
subject: Electrodes, Ion selective
subject: Nueces River (Tex.)
subject: Nueces Bay (Tex.)

description: The Nueces River and Bay were monitored every 2-4 weeks for 19 months for ammonia, nitrite, nitrate, phosphate, silicate, salinity, water level, river current and volume of water discharged from a sewage treatment plant located 10 km from the mouth of the river. A second sewage treatment plant discharging directly into the bay was also studied. Seasonal variations were explored, as well as geographic distribution of the nutrients. Measurements of dissolved organic nitrogen, particulate nitrogen, and estimates of nitrogen fixation, denitrification, sedimentation, other anthropogenic inputs, rain fall, and water exchange allowed calculation of the entire nitrogen budget for the river and bay. A variety of ion selective electrodes were evaluated for use as monitors of dissolved nitrogenous species in natural waters. A field ammonium monitor (FAM) was developed using a flow-through ammonia gas electrode, and deployed for up to 10 consecutive days in the outfall of the two sewage treatment plants. The instrument performed automatic calibrations and sample analysis every hour via on-board mixing of the sample with a basic solution prior to measuring the partial pressure of ammonia. For water samples containing 10-500 micromolar ammonia, the instrument analyses compared favorably with a Technicon AutoAnalyzer II employing the Berthelot reaction and measuring the adsorption of indophenol blue at 637 nm. The ammonium output of the plants were found to be highly variable on a daily basis, indicating the need for more frequent monitoring than the typical weekly or monthly sampling. An ammonium ion selective electrode was also used to monitor the Nueces River, using an additional temperature, pH and conductivity probe to calculate the sample water's ammonium ion activity. These waters contained a significant amount of seawater; the relatively high levels of sodium and potassium interfered with the ion selective membrane of the probe. An attempt to compensate for these interferences was only partially successful, confirming that the field use of ammonium ion electrodes are only possible in low conductivity fresh waters. The FAM, however, exhibited little salinity interference
The structure and function of G protein-coupled receptors
Creators: name: SEXTON, PATRICK
Publisher: name: Monash University
Year: 2021
Subjects: Pharmacology and pharmaceutical sciences not elsewhere classified

description: Membrane proteins are gatekeepers of cellular function with G protein-coupled receptors (GPCRs) that largest membrane protein family. This thesis describes the integrated application of study of GPCR structure with detailed molecular pharmacology and analytical pharmacological analysis of GPCRs and ligands to evolve our understanding of how activators differentially modulate GPCR function. This work is important for current and future drug discovery that targets this family of receptor proteins.
On first integrals of geodesic flows on a two-torus
Creators: name: Taimanov, I. A.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Dynamical Systems (math.DS)
subject: Differential Geometry (math.DG)
subject: FOS: Mathematics

description: The problem of the existence of an additional (independent on the energy) first integral, of a geodesic (or magnetic geodesic) flow, which is polynomial in momenta is studied. The relation of this problem to the existence of nontrivial solutions of stationary dispersionless limits of two-dimensional soliton equations is demonstrated. The nonexistence of an additional quadratic first integral is established for certain classes of magnetic geodesic flows.
description: 28 pages
Mining the forests: do protected areas hinder mining-driven forest loss in Sub-Saharan Africa?
Creators: name: Jean-Louis Combes
name: Motel, Pascale Combes
name: Manegdo Ulrich Doamba
name: Youba Ndiaye
Publisher: name: Zenodo
Year: 2023

description: DR LEO 2023-09
description: DR LEO - Working paper LEO - 2023-09
Suzaku Observations of Moderately Obscured (Compton-thin) Active Galactic Nuclei Selected by Swift/BAT Hard X-ray Survey
Creators: name: Kawamuro, Taiki
name: Ueda, Yoshihiro
name: Tazaki, Fumie
name: Ricci, Claudio
name: Terashima, Yuichi
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We report the results obtained by a systematic, broadband (0.5--150 keV) X-ray spectral analysis of moderately obscured (Compton-thin; $22 \leq \log N_{\rm H} < 24$) active galactic nuclei (AGNs) observed with Suzaku and Swift/Burst Alert Telescope (BAT). Our sample consists of 45 local AGNs at $z<0.1$ with $\log L_{\rm 14-195\1mmkeV} > 42$ detected in the Swift/BAT 70-month survey, whose Suzaku archival data are available as of 2015 December. All spectra are uniformly fit with a baseline model composed of an absorbed cutoff power-law component, reflected emission accompanied by a narrow fluorescent iron-K$α$ line from cold matter (torus), and scattered emission. Main results based on the above analysis are as follows. (1) The photon index is correlated with Eddington ratio, but not with luminosity or black hole mass. (2) The ratio of the iron-K$α$ line to X-ray luminosity, a torus covering fraction indicator, shows significant anti-correlation with luminosity. (3) The averaged reflection strength derived from stacked spectra above 14 keV is larger in less luminous ($\log L_{\rm 10-50\1mmkeV} \leq 43.3$; $R= 1.04^{+0.17}_{-0.19}$) or highly obscured AGNs ($\log N_{\rm H} > 23$; $R = 1.03^{+0.15}_{-0.17}$) than in more luminous ($\log L_{\rm 10-50\1mmkeV} > 43.3$; $R= 0.46^{+0.08}_{-0.09}$) or lightly obscured objects ($\log N_{\rm H} \leq 23$; $R = 0.59^{+0.09}_{-0.10}$), respectively. (4) The [O IV] 25.89 $μ$m line to X-ray luminosity ratio is significantly smaller in AGNs with lower soft X-ray scattering fractions, suggesting that the [O IV] 25.89 $μ$m luminosity underestimates the intrinsic power of an AGN buried in a small opening-angle torus.
description: Accepted for publication in ApJS, 38 pages
A Bregman Learning Framework for Sparse Neural Networks
Creators: name: Bungert, Leon
name: Roith, Tim
name: Tenbrinck, Daniel
name: Burger, Martin
Publisher: name: arXiv
Year: 2021
Subjects: subject: Machine Learning (cs.LG)
subject: Numerical Analysis (math.NA)
subject: Optimization and Control (math.OC)
subject: FOS: Computer and information sciences
subject: FOS: Mathematics
subject: I.2.6; F.2.1; G.1.6
subject: 65K10, 68T05, 90C26

description: We propose a learning framework based on stochastic Bregman iterations, also known as mirror descent, to train sparse neural networks with an inverse scale space approach. We derive a baseline algorithm called LinBreg, an accelerated version using momentum, and AdaBreg, which is a Bregmanized generalization of the Adam algorithm. In contrast to established methods for sparse training the proposed family of algorithms constitutes a regrowth strategy for neural networks that is solely optimization-based without additional heuristics. Our Bregman learning framework starts the training with very few initial parameters, successively adding only significant ones to obtain a sparse and expressive network. The proposed approach is extremely easy and efficient, yet supported by the rich mathematical theory of inverse scale space methods. We derive a statistically profound sparse parameter initialization strategy and provide a rigorous stochastic convergence analysis of the loss decay and additional convergence proofs in the convex regime. Using only 3.4% of the parameters of ResNet-18 we achieve 90.2% test accuracy on CIFAR-10, compared to 93.6% using the dense network. Our algorithm also unveils an autoencoder architecture for a denoising task. The proposed framework also has a huge potential for integrating sparse backpropagation and resource-friendly training.
description: 43 pages, 5 figures, some minor modifications, weakened assumptions
Odd thermodynamic limit for the Loschmidt echo
Creators: name: Torre, Gianpaolo
name: Marić, Vanja
name: Kuić, Domagoj
name: Franchini, Fabio
name: Giampaolo, Salvatore Marco
Publisher: name: arXiv
Year: 2021
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: High Energy Physics - Theory (hep-th)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Is it possible to readily distinguish a system made by an Avogadro's number of identical elements and one with a single additional one? Usually, the answer to this question is negative but, in this work, we show that in antiferromagnetic quantum spin rings a simple out-of-equilibrium experiment can do so, yielding two qualitatively and quantitatively different outcomes depending on whether the system includes an even or an odd number of elements. We consider a local quantum-quench setup and calculate a generating function of the work done, namely, the Loschmidt echo, showing that it displays different features depending on the presence or absence of topological frustration, which is triggered by the even/oddness in the number of the chain sites. We employ the prototypical quantum Ising chain to illustrate this phenomenology, which we argue being generic for antiferromagnetic spin chains, as it stems primarily from the different low energy spectra of frustrated and non frustrated chains. Our results thus prove that these well-known spectral differences lead indeed to distinct observable characteristics and open the way to harvest them in quantum thermodynamics protocols.
description: 10 pages, 3 figures. Updated to published version
The Exceptional Flare of Mrk 501 in 2014: Combined Observations with H.E.S.S. and FACT
Creators: name: Cologna, Gabriele
name: Chakraborty, Nachiketa
name: Jacholkowska, Agnieszka
name: Lorentz, Matthias
name: Mohamed, Mahmoud
name: Perennes, Cedric
name: Romoli, Carlo
name: Wagner, Stefan J.
name: Wierzcholska, Alicja
name: Dorner, Daniela
name: Kurtanidze, Omar
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: The BL Lac type object Mrk 501 was observed at very high energies (E > 100 GeV) in 2014 with the upgraded H.E.S.S. (High Energy Stereoscopic System) phase 2 array. The data collected with the central 28m telescope allow for a broader energy range extending to lower energies when compared to the one obtained with the four small telescopes alone. A strong flaring event with a flux level comparable to the 1997 historical maximum has been detected as a consequence of target of opportunity observations triggered by alerts from the FACT collaboration. The First G-APD Cherenkov Telescope (FACT) is continuously monitoring bright blazars at TeV energies providing important pre- and post-flare information. For the first time, the data and lightcurves from H.E.S.S. and FACT are compared. These contemporaneous observations allow for a better characterization of the source emission. In a multiwavelength context, more precise correlation studies between VHE and lower energies are possible thanks to the dense sampling of the FACT observations. The hard intrinsic spectrum detected by H.E.S.S. during the flare allows the derivation of strong constraints on the scale of Lorentz invariance violation via the non-detection of EBL opacity modifications and from time-of-flight studies.
description: 6 pages, 5 figures, proceeding Gamma 2016
The Leptonic Higgs Portal
Creators: name: Batell, Brian
name: Lange, Nicholas
name: McKeen, David
name: Pospelov, Maxim
name: Ritz, Adam
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: An extended Higgs sector may allow for new scalar particles well below the weak scale. In this work, we present a detailed study of a light scalar $S$ with enhanced coupling to leptons, which could be responsible for the existing discrepancy between experimental and theoretical determinations of the muon anomalous magnetic moment. We present an ultraviolet completion of this model in terms of the lepton-specific two-Higgs doublet model and an additional scalar singlet. We then analyze a plethora of experimental constraints on the universal low energy model, and this UV completion, along with the sensitivity reach at future experiments. The most relevant constraints originate from muon and kaon decays, electron beam dump experiments, electroweak precision observables, rare $B_d$ and $B_s$ decays and Higgs branching fractions. The properties of the leptonic Higgs portal imply an enhanced couplings to heavy leptons, and we identify the most promising search mode for the high-luminosity electron-positron colliders as $e^+{+}e^-\toτ^+{+}τ^-{+}S \to τ^+{+}τ^-{+}\ell{+}\bar \ell$, where $\ell =e,μ$. Future analyses of existing data from BaBar and Belle, and from the upcoming Belle II experiment, will enable tests of this model as a putative solution to the muon $g-2$ problem for $m_S < 3.5$ GeV.
description: 10 pages, 5 figures
Observation of the photon-blockade breakdown phase transition
Creators: name: Fink, J. M.
name: Dombi, A.
name: Vukics, A.
name: Wallraff, A.
name: Domokos, P.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Non-equilibrium phase transitions exist in damped-driven open quantum systems, when the continuous tuning of an external parameter leads to a transition between two robust steady states. In second-order transitions this change is abrupt at a critical point, whereas in first-order transitions the two phases can co-exist in a critical hysteresis domain. Here we report the observation of a first-order dissipative quantum phase transition in a driven circuit quantum electrodynamics (QED) system. It takes place when the photon blockade of the driven cavity-atom system is broken by increasing the drive power. The observed experimental signature is a bimodal phase space distribution with varying weights controlled by the drive strength. Our measurements show an improved stabilization of the classical attractors up to the milli-second range when the size of the quantum system is increased from one to three artificial atoms. The formation of such robust pointer states could be used for new quantum measurement schemes or to investigate multi-photon quantum many-body phases.
description: 7 pages, 4 figures
The entropy emission properties of near-extremal Reissner-Nordström black holes
Creators: name: Hod, Shahar
Publisher: name: arXiv
Year: 2016
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Bekenstein and Mayo have revealed an interesting property of evaporating $(3+1)$-dimensional Schwarzschild black holes: their entropy emission rates $\dot S_{\text{Sch}}$ are related to their energy emission rates $P$ by the simple relation $\dot S_{\text{Sch}}=C_{\text{Sch}}\times (P/\hbar)^{1/2}$. Remembering that $(1+1)$-dimensional perfect black-body emitters are characterized by the same functional relation, $\dot S^{1+1}=C^{1+1}\times(P/\hbar)^{1/2}$, Bekenstein and Mayo have concluded that, in their entropy emission properties, $(3+1)$-dimensional Schwarzschild black holes behave effectively as $(1+1)$-dimensional entropy emitters. One naturally wonders whether all black holes behave as simple $(1+1)$-dimensional entropy emitters? In order to address this interesting question, we shall study in this paper the entropy emission properties of Reissner-Nordström black holes. We shall show, in particular, that the physical properties which characterize the neutral sector of the Hawking emission spectra of these black holes can be studied {\it analytically} in the near-extremal $T_{\text{BH}}\to0$ regime. We find that the Hawking radiation spectra of massless neutral scalar fields and coupled electromagnetic-gravitational fields are characterized by the non-trivial entropy-energy relations $\dot S^{\text{Scalar}}_{\text{RN}} = -C^{\text{Scalar}}_{\text{RN}} \times (AP^3/\hbar^3)^{1/4} \ln(AP/\hbar)$ and $\dot S^{\text{Elec-Grav}}_{\text{RN}} = -C^{\text{Elec-Grav}}_{\text{RN}} \times (A^4P^9/\hbar^9)^{1/10} \ln(AP/\hbar)$ in the near-extremal $T_{\text{BH}}\to0$ limit (here $A$ is the surface area of the Reissner-Nordström black hole). Our analytical results therefore indicate that {\it not} all black holes behave as simple $(1+1)$-dimensional entropy emitters.
description: 5 pages
Synchrotron masers and fast radio bursts
Creators: name: Ghisellini, Gabriele
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Fast Radio Bursts (FRBs), with a typical duration of 1 ms and 1 Jy flux density at GHz frequencies, have brightness temperatures exceeding 1e33 K, requiring a coherent emission process. This can be achieved by bunching particles in volumes smaller than the typical wavelength, but this may be challenging. Alternatively, we can have maser emission. Under certain conditions, the synchrotron stimulated emission process can be more important than true absorption, and a synchrotron maser can be created. This occurs when the emitting electrons have a very narrow distribution of pitch angles and energies. This process overcomes the difficulties of having extremely dense bunches of particles and relaxes the light crossing time limits, since there is no simple relation between the actual size of the source and the observed variability timescale.
description: 4 pages 2 figures. Submitted to MNRAS Letters. Kind comments welcome
Simultaneous longitudinal and transverse oscillation in an active filament
Creators: name: Pant, V.
name: Mazumder, R.
name: Yuan, D.
name: Banerjee, D.
name: Srivastava, A. K.
name: Shen, Y.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We report on the co-existence of longitudinal and transverse oscillations in an active filament. On March 15$^{th}$ 2013, a M1.1 class flare was observed in the active region AR 11692. A CME was found to be associated with the flare. {The CME generated a shock wave that triggered the oscillations in a nearby filament}, situated at the south-west of the active region as observed from National Solar Observatory (NSO)\textit{Global Oscillation Network Group}(GONG) H$α$ images. In this work we report the longitudinal oscillations in the two ends of the filament, co-existing with the transverse oscillations. We propose a scenario in which {an} incoming shock wave hits the filament obliquely and triggers both longitudinal and transverse oscillations. Using the observed parameters, we estimate the lower limit of the magnetic field strength. We use simple pendulum model with gravity as the restoring force to estimate the radius of curvature. We also calculate the mass accretion rate which causes the filament motions to damp quite fast.
description: Accepted for publication in Solar Physics