cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Rapid computation of $L$-functions attached to Maass forms
Creators: name: Booker, Andrew R.
name: Then, Holger
Publisher: name: arXiv
Year: 2017
Subjects: subject: Number Theory (math.NT)
subject: FOS: Mathematics

description: Let $L$ be a degree-$2$ $L$-function associated to a Maass cusp form. We explore an algorithm that evaluates $t$ values of $L$ on the critical line in time $O(t^{1+\varepsilon})$. We use this algorithm to rigorously compute an abundance of consecutive zeros and investigate their distribution.
Momentum Analysis for Metasurfaces
Creators: name: Liu, Wenwei
name: Li, Zhancheng
name: Cheng, Hua
name: Chen, Shuqi
name: Tian, Jianguo
Publisher: name: arXiv
Year: 2017
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Utilizing discrete phase distribution to fit continuous phase distribution has been a primary routine for designing metasurfaces. In the existing method, the validation of the discrete designs is guaranteed only by using the sub-wavelength condition of unit cells, which is insufficient, especially for arbitrary phase distribution. Herein, we proposed an analytical method to design metasurfaces via estimating the width of the source in a unit cell. Also, by calculating field patterns in both real- and momentum-space, we provided four guidelines to direct future applications of metasurfaces, such as an arbitrary multi-foci lens with the same strength of each focus, a convex-concave double lens, and a lens with a large numerical aperture that can precisely prevent undesired diffraction orders. Besides metalens, this methodology can provide a wide platform for designing tailored and multifunctional metasurfaces in future, especially large-area ones in practical applications.
description: 10 pages, 9 figures
Model-independent study on the anomalous $ZZγ$ and $Zγγ$ couplings at the future muon collider
Creators: name: Senol, A.
name: Spor, S.
name: Gurkanli, E.
name: Cetinkaya, V.
name: Denizli, H.
name: Köksal, M.
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: In this study, we investigate the potential of $μ^{-} μ^{+}\to Zγ\to ν\barνγ$ process at the future muon collider with a center-of-mass energy of 3 TeV to examine the anomalous $ZZγ$ and $Zγγ$ neutral triple gauge couplings defining $CP$-conserving $C_{\widetilde{B}W}/{Λ^4}$ coupling and three $CP$-violating $C_{BB}/{Λ^4}$, $C_{BW}/{Λ^4}$, $C_{WW}/{Λ^4}$ couplings. All signal and relevant background events are generated in MadGraph and passed through Pythia for parton showering and hadronization. Detector effects are also considered via tuned muon detector cards in Delphes. The effects of systematic uncertainties of $0\%$, $3\%$ and $5\%$ on the sensitivities are studied. The best sensitivities obtained from the process $μ^{-} μ^{+}\to Zγ\to ν\barνγ$ are $[-6.53;6.64]\times10^{-2}$ TeV$^{-4}$ on $CP$-conserving $C_{\widetilde{B}W}/{Λ^4}$ coupling and $[-2.47;2.47]\times10^{-2}$ TeV$^{-4}$, $[-8.46;8.46]\times10^{-2}$ TeV$^{-4}$ and $[-2.20;2.20]\times10^{-1}$ TeV$^{-4}$ on $CP$-conserving $C_{BB}/{Λ^4}$, $C_{BW}/{Λ^4}$, $C_{WW}/{Λ^4}$ couplings , respectively. Our obtained results on the anomalous neutral gauge couplings set more stringent sensitivity, ranging between 5 and 15 times than the current experimental results while slightly better than the phenomenological studies at future pp colliders such as the HL-LHC, the HE-LHC and the FCC-hh, respectively. On the other hand, we can see that the bounds on the anomalous neutral gauge couplings expected to be obtained for the future $e^{-}e^{+}$ colliders such as the CLIC are roughly 2 times better than our results.
description: 21 pages, 9 figures
Improving Thompson Sampling via Information Relaxation for Budgeted Multi-armed Bandits
Creators: name: Jeong, Woojin
name: Min, Seungki
Publisher: name: arXiv
Year: 2024
Subjects: subject: Machine Learning (cs.LG)
subject: Artificial Intelligence (cs.AI)
subject: FOS: Computer and information sciences

description: We consider a Bayesian budgeted multi-armed bandit problem, in which each arm consumes a different amount of resources when selected and there is a budget constraint on the total amount of resources that can be used. Budgeted Thompson Sampling (BTS) offers a very effective heuristic to this problem, but its arm-selection rule does not take into account the remaining budget information. We adopt \textit{Information Relaxation Sampling} framework that generalizes Thompson Sampling for classical $K$-armed bandit problems, and propose a series of algorithms that are randomized like BTS but more carefully optimize their decisions with respect to the budget constraint. In a one-to-one correspondence with these algorithms, a series of performance benchmarks that improve the conventional benchmark are also suggested. Our theoretical analysis and simulation results show that our algorithms (and our benchmarks) make incremental improvements over BTS (respectively, the conventional benchmark) across various settings including a real-world example.
description: accepted
Binary adaptive embeddings from order statistics of random projections
Creators: name: Valsesia, Diego
name: Magli, Enrico
Publisher: name: arXiv
Year: 2017
Subjects: subject: Machine Learning (cs.LG)
subject: Information Retrieval (cs.IR)
subject: FOS: Computer and information sciences

description: We use some of the largest order statistics of the random projections of a reference signal to construct a binary embedding that is adapted to signals correlated with such signal. The embedding is characterized from the analytical standpoint and shown to provide improved performance on tasks such as classification in a reduced-dimensionality space.
Spin interaction and magnetism in cobaltate Kitaev candidate materials: an $ab$ $initio$ and model Hamiltonian approach
Creators: name: Pandey, Shishir Kumar
name: Feng, Ji
Publisher: name: arXiv
Year: 2022
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: In the quest for materials hosting Kitaev spin liquids, much of the efforts have been focused on the fourth- and fifth-row transition metal compounds, which are spin-orbit coupling assisted Mott insulators. Here, we study the structural and magnetic properties of 3$d$ transition metal oxides, Na$_2$Co$_2$TeO$_6$ and Na$_3$Co$_2$SbO$_6$. The partial occupancy of sodium in former compound is addressed using a cluster expansion, and a honeycomb lattice of sodiums is found to be energetically favored. Starting from the \textit{ab initio} band structures, a many-body second order perturbation theory leads to a pseudospin-$\frac{1}{2}$ Hamiltonian with estimated magnetic interactions. We show that the experimentally observed zigzag magnetic state is stabilized only when the first neighbor Kitaev coupling dominates over the Heisenberg term, both of which are highly suppressed due to presence of $e_g$ orbitals. A third neighbor Heisenberg interaction is found dominant in both these compounds. We also present a phase diagram for Na$_2$Co$_2$TeO$_6$ by varying the electron-electron and spin-orbit interactions. The computed spin excitation spectra are found to capture essential features of recent experimental magnon spectrum, lending support to our results.
Supersonic Combustion Diagnostics with Dual Comb Spectroscopy
Creators: name: Yun, David
name: Malarich, Nathan A.
name: Cole, Ryan K.
name: Egbert, Scott C.
name: France, Jacob J.
name: Liu, Jiwen
name: Rice, Kristin M.
name: Hagenmaier, Mark A.
name: Donbar, Jeffrey M.
name: Hoghooghi, Nazanin
name: Coburn, Sean C.
name: Rieker, Gregory B.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Applied Physics (physics.app-ph)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Supersonic engine development requires accurate and detailed measurements of fluidic and thermodynamic parameters to optimize engine designs and benchmark computational fluid dynamic (CFD) simulations. Here, we demonstrate that dual frequency comb spectroscopy (DCS) with mode-locked frequency combs can provide simultaneous absolute measurements of several flow parameters with low uncertainty across a range of conditions owing to the broadband and ultrastable optical frequency output of the lasers. We perform DCS measurements across a 6800-7200 cm-1 bandwidth covering hundreds of H2O absorption features resolved with a spectral point spacing of 0.0067 cm-1 and point spacing precision of 1.68 x 10-10 cm-1. We demonstrate 2D profiles of velocity, temperature, pressure, water mole fraction, and air mass flux in a ground-test dual-mode ramjet at Wright-Patterson Air Force Base. The narrow angles of the measurement beams offer sufficient spatial resolution to resolve properties across an oblique shock train in the isolator and the thermal throat of the combustor. We determine that the total measurement uncertainties for the various parameters range from 1% for temperature to 9% for water vapor mole fraction, with the absorption database/model that is used to interpret the data typically contributing the most uncertainty (leaving the door open for even lower uncertainty in the future). CFD at the various measurement locations show good agreement, largely falling within the DCS measurement uncertainty for most profiles and parameters.
Variations of BPS structure and a large rank limit
Creators: name: Scalise, Jacopo
name: Stoppa, Jacopo
Publisher: name: arXiv
Year: 2017
Subjects: subject: Algebraic Geometry (math.AG)
subject: High Energy Physics - Theory (hep-th)
subject: Differential Geometry (math.DG)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: We study a class of flat bundles, of finite rank $N$, which arise naturally from the Donaldson-Thomas theory of a Calabi-Yau threefold $X$ via the notion of a variation of BPS structure. We prove that in a large $N$ limit their flat sections converge to the solutions to certain infinite dimensional Riemann-Hilbert problems recently found by Bridgeland. In particular this implies an expression for the positive degree, genus $0$ Gopakumar-Vafa contribution to the Gromov-Witten partition function of $X$ in terms of solutions to confluent hypergeometric differential equations.
description: 35 pages
Five-fold Symmetry in Au-Si Metallic Glass
Creators: name: He, Chang-Chun
name: Xu, Shao-Gang
name: Qiu, Shao-Bin
name: He, Chao
name: Zhao, Yu-Jun
name: Yang, Xiao-Bao
name: Xu, Hu
Publisher: name: arXiv
Year: 2022
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: The first metallic glass of Au-Si alloy has been discovered for over half a century, but its atomic structure is still puzzling. Herein, Au 8 Si dodecahedrons with local five-fold symmetry are revealed as building blocks in Au-Si metallic glass, and the interconnection modes of Au 8 Si dodecahedrons determine the medium-range order. With dimensionality reduction, the surface ordering is attributed to the motif transformation of Au 8 Si dodecahedrons into planar Au 5 Si pyramids with five-fold symmetry, and thus the self-assembly of Au 5 Si pyramids leads to the formation of the ordered Au 2 Si monolayer with the lowest energy. Furthermore, the structural similarity analysis is performed to unveil the physical origin of structural characteristics in different dimensions. The amorphism of Au-Si is due to the smooth energy landscape around the global minimum, while the ordered surface structure occurs due to the steep energy landscape.
Cylinder quantum field theories at small coupling
Creators: name: Dogaru, Andrei Ioan
name: Delgado, Ruben Campos
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We show that any 2D scalar field theory compactified on a cylinder and with a Fourier expandable potential $V$ is equivalent, in the small coupling limit, to a 1D theory involving a massless particle in a potential $V$ and an infinite tower of free massive Kaluza-Klein (KK) modes. Moving slightly away from the deep IR region has the effect of switching on interactions between the zero mode and the KK modes, whose strength is controlled by powers of the coupling, hence making the interactions increasingly suppressed. We take the notable example of Liouville field theory and, starting from its worldline version, we compute the torus (one-loop) partition function perturbatively in the coupling constant. The partition function at leading order is invariant under a T-duality transformation that maps the radius of the cylinder to its inverse and rescales it by the square of the Schwinger parameter of the cylinder. We show that this behavior is a universal feature of cylinder QFTs.
description: 14 pages; v3: added new sections and comments, corrected typos
Astrophotonics -- current capabilities and the road ahead
Creators: name: Norris, Barnaby
name: Gross, Simon
name: Leon-Saval, Sergio G.
name: Betters, Christopher H.
name: Bryant, Julia
name: Yu, Qingshan
name: Wang, Adeline Haobing
name: Douglass, Glen
name: Arcadi, Elizabeth
name: Sanny, Ahmed
name: Withford, Michael
name: Tuthill, Peter
name: Bland-Hawthorn, Joss
Publisher: name: arXiv
Year: 2024
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: Astrophotonics represents a cutting-edge approach in observational astronomy. This paper explores the significant advancements and potential applications of astrophotonics, highlighting how photonic technologies stand to revolutionise astronomical instrumentation. Key areas of focus include photonic wavefront sensing and imaging, photonic interferometry and nulling, advanced chip fabrication methods, and the integration of spectroscopy and sensing onto photonic chips. The role of single-mode fibres in reducing modal noise, and the development of photonic integral field units (IFUs) and arrayed waveguide gratings (AWGs) for high-resolution, spatially resolved spectroscopy will be examined. As part of the Sydney regional-focus issue, this review aims to detail some of the current technological achievements in this field as well as to discuss the future trajectory of astrophotonics, underscoring its potential to unlock important new astronomical discoveries.
description: Published version available at https://opg.optica.org/ao/fulltext.cfm?uri=ao-63-24-6393&id=554618
The Performance of the Robo-AO Laser Guide Star Adaptive Optics System at the Kitt Peak 2.1-m Telescope
Creators: name: Jensen-Clem, Rebecca
name: Duev, Dmitry A.
name: Riddle, Reed
name: Salama, Maïssa
name: Baranec, Christoph
name: Law, Nicholas M.
name: Kulkarni, S. R.
name: Ramprakash, A. N.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: Robo-AO is an autonomous laser guide star adaptive optics system recently commissioned at the Kitt Peak 2.1-m telescope. Now operating every clear night, Robo-AO at the 2.1-m telescope is the first dedicated adaptive optics observatory. This paper presents the imaging performance of the adaptive optics system in its first eighteen months of operations. For a median seeing value of $1.31^{\prime\prime}$, the average Strehl ratio is 4\% in the $i^\prime$ band and 29\% in the J band. After post-processing, the contrast ratio under sub-arcsecond seeing for a $2\leq i^{\prime} \leq 16$ primary star is five and seven magnitudes at radial offsets of $0.5^{\prime\prime}$ and $1.0^{\prime\prime}$, respectively. The data processing and archiving pipelines run automatically at the end of each night. The first stage of the processing pipeline shifts and adds the data using techniques alternately optimized for stars with high and low SNRs. The second "high contrast" stage of the pipeline is eponymously well suited to finding faint stellar companions.
description: 12 pages, 16 figures, to be submitted to PASP
Ab initio structural optimization at finite temperatures based on anharmonic phonon theory: Application to the structural phase transitions of BaTiO$_3$
Creators: name: Masuki, Ryota
name: Nomoto, Takuya
name: Arita, Ryotaro
name: Tadano, Terumasa
Publisher: name: arXiv
Year: 2022
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We formulate a first-principle scheme for structural optimization at finite temperature ($T$) based on the self-consistent phonon (SCP) theory, which accurately takes into account the effect of strong phonon anharmonicity. The $T$-dependence of the shape of the unit cell and internal atomic configuration is determined by minimizing the variational free energy in the SCP theory. At each optimization step, the interatomic force constants in the new structure are calculated without running additional electronic structure calculations, which makes the method dramatically efficient. We demonstrate that the thermal expansion of silicon and the three-step structural phase transitions in BaTiO$_3$ and its pressure-temperature ($p$-$T$) phase diagram are successfully reproduced. The present formalism will open the way to the non-empirical prediction of physical properties at finite $T$ of materials having a complex structural phase diagram.
Fast and Lightweight Rate Control for Onboard Predictive Coding of Hyperspectral Images
Creators: name: Valsesia, Diego
name: Magli, Enrico
Publisher: name: arXiv
Year: 2017
Subjects: subject: Information Theory (cs.IT)
subject: FOS: Computer and information sciences

description: Predictive coding is attractive for compression of hyperspecral images onboard of spacecrafts in light of the excellent rate-distortion performance and low complexity of recent schemes. In this letter we propose a rate control algorithm and integrate it in a lossy extension to the CCSDS-123 lossless compression recommendation. The proposed rate algorithm overhauls our previous scheme by being orders of magnitude faster and simpler to implement, while still providing the same accuracy in terms of output rate and comparable or better image quality.
Weak value controversy
Creators: name: Vaidman, Lev
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Recent controversy regarding the meaning and usefulness of weak values is reviewed. It is argued that in spite of recent statistical arguments by Ferrie and Combes, experiments with anomalous weak values provide a useful amplification techniques for precision measurements of small effects in many realistic situations. The statistical nature of weak vales was questioned. Although measuring weak value requires an ensemble, it is argued that the weak value, similarly to an eigenvalue, is a property of a single pre- and post-selected quantum system.
Scalable quantum control and non-abelian anyon creation in the Kitaev honeycomb model
Creators: name: Raii, Omar
name: Mintert, Florian
name: Burgarth, Daniel
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The Kitaev honeycomb model is a system allowing for experimentally realisable quantum computation with topological protection of quantum information. Practical implementation of quantum information processing typically relies on adiabatic, i.e. slow dynamics. Here we show that the restriction to adiabatic dynamics can be overcome with optimal control theory, enabled by an extension of the fermionization of the Kitaev honeycomb model to the time-dependent case. Moreover we present a quantum control method that is applicable to large lattice models due to sub-exponential scaling.
description: 12 pages, 10 figures
Facts on Growing and Use of Eucalyptus in Kenya
Creators: name: Oballa, P.O.
name: Konuche, P.K.
name: Muchiri, M.N.
name: Kigomo, B.N.
Publisher: name: Kenya Forestry Research Institute
Year: 2010
Subjects: Forestry
Kenya

description: Eucalypts are the most widely cultivated forest trees in the world. The genus Eucalyptus comprises more than 900 species and various hybrids and varieties. Most eucalypts occur naturally in Australia. In Kenya, eucalypts were introduced in 1902 to provide fuelwood for the Kenya-Uganda railway. Currently, eucalypts are used for fuelwood, timber, plywood, transmission poles, pulp, building materials, fencing posts, windbreaks and ornamentals. Eucalypts are grown in most ecological zones in Kenya and on a variety of soils, including infertile sands and heavy clays. The total area under eucalypts in Kenya is about 100,000 ha distributed in gazetted forests and land owned by large private companies, small-scale farmers and local authorities. The area under Eucalyptus is likely to increase as a result of the high demand for transmission poles to cater for the ongoing expansion in rural electrification and for construction, fuelwood, carbon sequestration and mitigation of the effects of climate change. A ready market for Eucalyptus products has motivated farmers to grow the species to improve their livelihoods through increased income. However, the extensive growth of eucalypts has generated controversy on high water use by the species and negative effects on soil fertility and biodiversity. Concerns have also been expressed about the adverse effects of growing eucalypts near water sources because of the observed drying of streams, rivers and springs. Nevertheless, farmers continue to grow Eucalyptus because of its fast growth and good economic returns. To address these concerns, the government has recently provided guidelines on growing Eucalyptus trees and is presently working on a policy to guide the growth of the species in Kenya. As a third government effort, this booklet presents important facts on the growing and use of Eucalyptus in Kenya. The booklet will contribute to the effective growth of Eucalyptus with minimum adverse effects on the environment, leading to increased forest cover, carbon storage and renewable energy, improved livelihood and creating wealth for the citizens.
Disorder effects on triple-point fermions
Creators: name: Hsu, Hsiu-Chuan
name: Fulga, Ion Cosma
name: You, Jhih-Shih
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: The stability of three-dimensional relativistic semimetals to disorder has recently attracted great attention, but the effect of disorder remains elusive for multifold fermions, that are not present in the framework of quantum field theory. In this paper, we investigate one type of multifold fermions, so-called triple-point fermions (TPFs), which have pseudospin-1 degrees of freedom and topological charges $\pm2$. Specifically, we consider the effect of disorder on a minimal, three-band tight-binding model, which realizes the minimal number of two TPFs. The numerically-obtained, disorder-averaged density of states suggests that, within a finite energy window, the TPFs are robust up to a critical strength of disorder. In the strong disorder regime, the inter-TPF scattering is the main mechanism for destroying a single TPF. Moreover, we study the effects of disorder on the distribution of Fermi arcs and surface Berry curvature. We demonstrate that the Fermi arc retains its sharpness at weak disorder, but gradually dissolves into the metallic bulk for stronger disorder. In clean limit, the surface Berry curvature exhibits a bipolar configuration in the surface Brillouin zone. With increasing disorder, the positive and negative surface Berry curvature start to merge at the nearby momenta where the Fermi arcs penetrate into bulk.
description: 5+3 pages, 8 figures
Strong anisotropy effect in iron-based superconductor CaFe$_{0.882}$Co$_{0.118}$AsF
Creators: name: Ma, Yonghui
name: Ji, Qiucheng
name: Hu, Kangkang
name: Gao, Bo
name: Li, Wei
name: Mu, Gang
name: Xie, Xiaoming
Publisher: name: arXiv
Year: 2017
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: The anisotropy of the Fe-based superconductors is much smaller than that of the cuprates and the theoretical calculations. A credible understanding for this experimental fact is still lacking up to now. Here we experimentally study the magnetic-field-angle dependence of electronic resistivity in the superconducting phase of iron-based superconductor CaFe$_{0.882}$Co$_{0.118}$AsF, and find the strongest anisotropy effect of the upper critical field among the iron-based superconductors based on the framework of Ginzburg-Landau theory. The evidences of energy band structure and charge density distribution from electronic structure calculations demonstrate that the observed strong anisotropic effect mainly comes from the strong ionic bonding in between the ions of Ca$^{2+}$ and F$^-$, which weakens the interlayer coupling between the layers of FeAs and CaF. This finding provides a significant insight into the nature of experimentally observed strong anisotropic effect of electronic resistivity, and also paves an avenue to design exotic two dimensional artificial unconventional superconductors in future.
description: 5 pages, 3 figures, accepted to Supercond. Sci. Technol
Landscape Restoration in Kenya Addressing Gender Equality
Creators: name: (:Unkn) Unknown
Publisher: name: Kenya Forestry Research Institue
Year: 2020
Subjects: Gender
Kenya

description: Unlocking the potential of forest landscape restoration (FLR) to achieve both social and environmental outcomes rests critically on the support, contributions and cooperation of a wide range of stakeholders at all levels, including women and men. In Kenya, the government has committed to restoring 5.1 million hectares of land by 2030. At the same time, Kenya’s commitment to promoting gender equality and women’s empowerment is enshrined in its Constitution, various national laws and policies as well as international conventions, including the Sustainable Development Goal framework. The purpose of this study was to provide empirically grounded lessons on opportunities and challenges for addressing gender in landscape restoration in Kenya, as well as to share recommendations for making sure Kenya’s ambitious restoration efforts do not repeat the mistakes of past gender-blind restoration initiatives, but make sure both women and men are able to enjoy the opportunities and benefits generated through landscape restoration.
Large deviations theory for noisy non-linear electronics: CMOS inverter as a case study
Creators: name: Gopal, Ashwin
name: Esposito, Massimiliano
name: Freitas, Nahuel
Publisher: name: arXiv
Year: 2022
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: The latest generation of transistors are nanoscale devices whose performance and reliability are limited by thermal noise in low-power applications. Therefore developing efficient methods to compute the voltage and current fluctuations in such non-linear electronic circuits is essential. Traditional approaches commonly rely on adding Gaussian white noise to the macroscopic dynamical circuit laws, but do not capture rare fluctuations and lead to thermodynamic inconsistencies. A correct and thermodynamically consistent approach can be achieved by describing single-electron transfers as Poisson jump processes accounting for charging effects. But such descriptions can be computationally demanding. To address this issue, we consider the macroscopic limit which corresponds to scaling up the physical dimensions of the transistor and resulting in an increase of the number of electrons on the conductors. In this limit, the thermal fluctuations satisfy a Large Deviations Principle which we show is also remarkably precise in settings involving only a few tens of electrons, by comparing our results with Gillespie simulations and spectral methods. Traditional approaches are recovered by resorting to an ad hoc diffusive approximation introducing inconsistencies. To illustrate these findings, we consider a low-power CMOS inverter, or NOT gate, which is a basic primitive in electronic design. Voltage (resp. current) fluctuations are obtained analytically (semi-analytically) and reveal interesting features.
Working with Flow: Workflows for Accessing 4CH Services
Creators: name: Dritsou, Vicky
name: Felicetti, Achille
name: Constantopoulos, Panos
Publisher: name: Zenodo
Year: 2023
Subjects: Workflows
Access to services
Process modelling

description: An abstract model that represents the general workflow for accessing CC services. A sequence of actions required to beperformed by users to fulfill access requests. Adaptable through specializations, capable to express the established parameters.
Quantum transport of a spin-1 chiral fermion
Creators: name: Kikuchi, Risako
name: Funato, Takumi
name: Yamakage, Ai
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We theoretically study the quantum transport in a three-dimensional spin-1 chiral fermion system in the presence of impurity scattering. Within the self-consistent Born approximation, we find peak structure of the density of states and significant suppression of electrical conductivity around the zero energy. The zero-energy conductivity depends less on impurity concentration, unlike a Weyl fermion. These properties originate from the flat band structure of spin-1 chiral fermion.
description: 10pages, 5figures
Landscape Restoration in Kenya Stocktaking of Key Innovations and Strategies
Creators: name: Service, Kenya Forest
Publisher: name: Kenya Forest Service
Year: 2020
Subjects: FORESTRY, AGRICULTURAL SCIENCES and LANDSCAPE PLANNING::Plant production::Forestry
Kenya

description: In Kenya, forest and landscape restoration (FLR) is a high priority on the government’s agenda, reflected by the large number of initiatives, legislations and policies associated with addressing degradation. These government policies, when implemented with strong communities’ participation, can also be part of a national strategy to implement the Sustainable Development Goals (SDGs). While these initiatives demonstrate a strong commitment to FLR and associated ecosystem services, implementing them at scale requires proper planning and assessment of the existing opportunities and resources. Towards this end, the Government established a multi-stakeholder Landscape Restoration Technical Working Group (LRTWG) in 2014 led by the Kenya Forest Service (KFS) to spearhead this planning and assessment processes. The LRTWG carried out an assessment of potential restoration opportunities and identified the most pressing land use challenges, restoration options and opportunities. This study is part of this process and sought to undertake a survey of a selection of successful FLR projects in Kenya, from which lessons can be drawn and scaled up to the national level. With a focus on key innovations, this work aims at providing a key building block towards a National Restoration Strategy, which will drive Kenya’s stated ambitious goal of restoring 5.1 million hectares of land – including forests, rangelands and croplands – by 2030.
Multi-epoch, high spatial resolution observations of multiple T Tauri systems
Creators: name: Csépány, Gergely
name: Ancker, Mario van den
name: Ábrahám, Péter
name: Köhler, Rainer
name: Brandner, Wolfgang
name: Hormuth, Felix
name: Hiss, Hector
Publisher: name: arXiv
Year: 2017
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Context. In multiple pre-main-sequence systems the lifetime of circumstellar disks appears to be shorter than around single stars, and the actual dissipation process may depend on the binary parameters of the systems. Aims. We report high spatial resolution observations of multiple T Tauri systems at optical and infrared wavelengths. We determine if the components are gravitationally bound and orbital motion is visible, derive orbital parameters and investigate possible correlations between the binary parameters and disk states. Methods. We selected 18 T Tau multiple systems (16 binary and two triple systems, yielding $16 + 2\times2=20$ binary pairs) in the Taurus-Auriga star forming region from the survey by Leinert et al. (1993), with spectral types from K1 to M5 and separations from 0.22" (31 AU) to 5.8" (814 AU). We analysed data acquired in 2006-07 at Calar Alto using the AstraLux lucky imaging system, along with data from SPHERE and NACO at the VLT, and from the literature. Results. We found ten pairs to orbit each other, five pairs that may show orbital motion and five likely common proper motion pairs. We found no obvious correlation between the stellar parameters and binary configuration. The 10 $μ$m infra-red excess varies between 0.1 and 7.2 magnitudes (similar to the distribution in single stars, where it is between 1.7 and 9.1), implying that the presence of the binary star does not greatly influence the emission from the inner disk. Conclusions. We have detected orbital motion in young T Tauri systems over a timescale of $\approx20$ years. Further observations with even longer temporal baseline will provide crucial information on the dynamics of these young stellar systems.
description: Accepted by A&A
A reduced model for salt-finger convection in the small diffusivity ratio limit
Creators: name: Xie, Jin-Han
name: Miquel, Benjamin
name: Julien, Keith
name: Knobloch, Edgar
Publisher: name: arXiv
Year: 2016
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences
subject: 76Fxx, 76Rxx

description: A simple model of nonlinear salt-finger convection in two dimensions is derived and studied. The model is valid in the limit of small solute to heat diffusivity ratio and large density ratio, which is relevant to both oceanographic and astrophysical applications. Two limits distinguished by the magnitude of the Schmidt number are found. For order one Schmidt numbers, appropriate for astrophysical applications, a modified Rayleigh-Bénard system with large-scale damping due to a stabilizing temperature is obtained. For large Schmidt numbers, appropriate for the oceanic setting, the model combines a prognostic equation for the solute field and a diagnostic equation for inertia-free momentum dynamics. Two distinct saturation regimes are identified for the second model: The weakly driven regime is characterized by a large-scale flow associated with a balance between advection and linear instability, while the strongly driven regime produces multiscale structures, resulting in a balance between the energy input through linear instability and the energy transfer between scales. For both regimes, we analytically predict and numerically confirm the dependence of the kinetic energy and salinity fluxes on the ratio between solute and heat Rayleigh numbers. The spectra and probability density functions are also computed.
description: 25 pages, 16 figures
High-efficiency, 80-mm aperture metalens telescope
Creators: name: Zhang, Lidan
name: Chang, Shengyuan
name: Chen, Xi
name: Ding, Yimin
name: Rahman, Md Tarek
name: Duan, Yao
name: Stephen, Mark
name: Ni, Xingjie
Publisher: name: arXiv
Year: 2022
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Metalenses, artificially engineered subwavelength nanostructures to focus light within ultrathin thickness, promise potential for a paradigm shift of conventional optical devices. However, the aperture sizes of metalenses are usually bound within hundreds of micrometers by the commonly-used scanning-based fabrication methods, limiting their usage on practical optical devices like telescopes. Here, for the first time, we demonstrate a high-efficiency, single-lens, refractive metalens telescope. We developed a mass production-friendly workflow for fabricating wafer-scale (80-mm aperture) metalenses using deep-ultraviolet (DUV) photolithography and a multi-exposure process involving reticle rotation and pattern stitching to leverage the radial symmetry of metalenses. Our metalens works in the near-infrared region (1200 - 1600 nm) with diffraction-limited performance and a high peak focusing efficiency of 80.84% at 1450 nm experimentally. Based on the metalens, we built a single-lens telescope and acquired images of the lunar surface, revealing its geographical structures. We believe our demonstration of the metalens telescope proves the exciting potential lying in the metasurfaces and could bring new possibilities for areas involving large optical systems, including geosciences, planetary observation, and astrophysical science.
Cosmological constraints on decaying axion-like particles: a global analysis
Creators: name: Balázs, Csaba
name: Bloor, Sanjay
name: Gonzalo, Tomás E.
name: Handley, Will
name: Hoof, Sebastian
name: Kahlhoefer, Felix
name: Lecroq, Marie
name: Marsh, David J. E.
name: Renk, Janina J.
name: Scott, Pat
name: Stöcker, Patrick
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Axion-like particles (ALPs) decaying into photons are known to affect a wide range of astrophysical and cosmological observables. In this study we focus on ALPs with masses in the keV-MeV range and lifetimes between $10^4$ and $10^{13}$ seconds, corresponding to decays between the end of Big Bang Nucleosynthesis and the formation of the Cosmic Microwave Background (CMB). Using the CosmoBit module of the global fitting framework GAMBIT, we combine state-of-the-art calculations of the irreducible ALP freeze-in abundance, primordial element abundances (including photodisintegration through ALP decays), CMB spectral distortions and anisotropies, and constraints from supernovae and stellar cooling. This approach makes it possible for the first time to perform a global analysis of the ALP parameter space while varying the parameters of $Λ$CDM as well as several nuisance parameters. We find a lower bound on the ALP mass of around $m_a > 300\,\text{keV}$, which can only be evaded if ALPs are stable on cosmological timescales. Future observations of CMB spectral distortions with a PIXIE-like mission are expected to improve this bound by two orders of magnitude.
description: 29+16 pages, 9 figures. V2 corresponds to the published version. Auxiliary material available on Zenodo at https://zenodo.org/record/6573347
Towards Faithful and Consistent Explanations for Graph Neural Networks
Creators: name: Zhao, Tianxiang
name: Luo, Dongsheng
name: Zhang, Xiang
name: Wang, Suhang
Publisher: name: arXiv
Year: 2022
Subjects: subject: Machine Learning (cs.LG)
subject: Social and Information Networks (cs.SI)
subject: FOS: Computer and information sciences

description: Uncovering rationales behind predictions of graph neural networks (GNNs) has received increasing attention over recent years. Instance-level GNN explanation aims to discover critical input elements, like nodes or edges, that the target GNN relies upon for making predictions. Though various algorithms are proposed, most of them formalize this task by searching the minimal subgraph which can preserve original predictions. However, an inductive bias is deep-rooted in this framework: several subgraphs can result in the same or similar outputs as the original graphs. Consequently, they have the danger of providing spurious explanations and fail to provide consistent explanations. Applying them to explain weakly-performed GNNs would further amplify these issues. To address this problem, we theoretically examine the predictions of GNNs from the causality perspective. Two typical reasons of spurious explanations are identified: confounding effect of latent variables like distribution shift, and causal factors distinct from the original input. Observing that both confounding effects and diverse causal rationales are encoded in internal representations, we propose a simple yet effective countermeasure by aligning embeddings. Concretely, concerning potential shifts in the high-dimensional space, we design a distribution-aware alignment algorithm based on anchors. This new objective is easy to compute and can be incorporated into existing techniques with no or little effort. Theoretical analysis shows that it is in effect optimizing a more faithful explanation objective in design, which further justifies the proposed approach.
description: Accepted by WSDM2023
Assessments and interventions for individuals accessing physiotherapy care via synchronous telehealth. A scoping review.
Creators: name: Davies, Luke
Publisher: name: OSF Registries
Year: 2024
Subjects: subject: Other Medicine and Health Sciences
subject: Medicine and Health Sciences
subject: physical therapy
subject: physiotherapy
subject: telehealth

description: The aim of this scoping review is to assess the current literature to i) determine what types of assessments and interventions have been delivered via synchronous forms of telehealth (videoconferencing and telephone) by physiotherapists ii) determine which populations have received synchronous telehealth delivered physiotherapy assessments and interventions.
A model for pion-pion scattering in large-N QCD
Creators: name: Veneziano, Gabriele
name: Yankielowicz, Shimon
name: Onofri, Enrico
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Following up on recent work by Caron-Huot et al. we consider a generalization of the old Lovelace-Shapiro model as a toy model for Pi-Pi scattering satisfying (most of) the properties expected to hold in ('t Hooft's) large-N limit of massless QCD. In particular, the model has asymptotically linear and parallel Regge trajectories at positive t, a positive leading Regge intercept $α_0 < 1$, and an effective bending of the trajectories in the negative-t region producing a fixed branch point at J=0 for $t < t_0 < 0$. Fixed (physical) angle scattering can be tuned to match the power-like (including logarithmic corrections) behavior predicted by perturbative QCD: $A(s,t) ~ s^{-β} \log(s)^{-γ} F(θ)$. Tree-level unitarity (i.e. positivity of residues for all values of s and J) imposes strong constraints on the allowed region in the alpha_0-beta-gamma parameter space, which nicely includes a physically interesting region around $α_0 = 0.5$, $β= 2$ and $γ= 3$. The full consistency of the model would require an extension to multi-pion processes, a program we do not undertake in this paper.
description: 17 pages, 6 figures
Model-based reinforcement learning in differential graphical games
Creators: name: Kamalapurkar, Rushikesh
name: Klotz, Justin R.
name: Walters, Patrick
name: Dixon, Warren E.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Systems and Control (eess.SY)
subject: Optimization and Control (math.OC)
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Mathematics

description: This paper seeks to combine differential game theory with the actor-critic-identifier architecture to determine forward-in-time, approximate optimal controllers for formation tracking in multi-agent systems, where the agents have uncertain heterogeneous nonlinear dynamics. A continuous control strategy is proposed, using communication feedback from extended neighbors on a communication topology that has a spanning tree. A model-based reinforcement learning technique is developed to cooperatively control a group of agents to track a trajectory in a desired formation. Simulation results are presented to demonstrate the performance of the developed technique.
Fast Magnetic Reconnection: "Ideal" Tearing and the Hall Effect
Creators: name: Pucci, Fulvia
name: Velli, Marco
name: Tenerani, Anna
Publisher: name: arXiv
Year: 2017
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Physical sciences

description: One of the main questions in magnetic reconnection is the origin of triggering behavior with on/off properties that accounts, once it is activated, for the fast magnetic energy conversion to kinetic and thermal energies at the heart of explosive events in astrophysical and laboratory plasmas. Over the past decade progress has been made on the initiation of fast reconnection via the plasmoid instability and what has been called "ideal" tearing, which sets in once current sheets thin to a critical inverse aspect ratio $(a/L)_c$: as shown by Pucci and Velli (2014), at $(a/L)_c \sim S^{-1/3}$ the time scale for the instability to develop becomes of the order of the Alfvén time and independent of the Lundquist number (here defined in terms of current sheet length $L$). However, given the large values of $S$ in natural plasmas, this transition might occur for thicknesses of the inner resistive singular layer which are comparable to the ion inertial length $d_i$. When this occurs, Hall currents produce a three-dimensional quadrupole structure of magnetic field, and the dispersive waves introduced by the Hall effect accelerate the instability. Here we present a linear study showing how the "ideal" tearing mode critical aspect ratio is modified when Hall effects are taken into account, including more general scaling laws of the growth rates in terms of sheet inverse aspect ratio: the critical inverse aspect ratio is amended to $a/L \simeq (di/L)^ {0.29} (1/S)^{0.19}$, at which point the instability growth rate becomes Alfvénic and does not depend on either of the (small) parameters $d_i/L, 1/S$. We discuss the implications of this generalized triggering aspect ratio for recently developed phase diagrams of magnetic reconnection.
First steps towards a workflow for 3D-models based on IIIF
Creators: name: Gautschy, Rita
Publisher: name: Zenodo
Year: 2023
Subjects: 3D-models
annotation
workflow
open source tools

description: Images play an important role in archaeological research and the 3D medium is becoming increasingly popular: 3D scans of archaeological objects, geo-referenced 3D scans of structures, e.g. tombs, or reflectance transformation imaging (RTI) are increasingly likely to form one part of the digital data created in research projects or by cultural heritage institutions. 3D offers many application possibilities that can contribute significantly to knowledge acquisition. Very often, however, the resulting files are extremely large and not really suited for smooth display. The situation is further complicated by the fact that there is still no real standard for both long-term storage and dissemination of 3D images. For a data repository such as the Swiss National Data and Service Center for the Humanities (DaSCH) which provides a “living archive” where data can be accessed and searched directly by humans as well as by machines, 3D images pose a series of questions and challenges. The original 3D-models are often several gigabytes large and their key features, the geometry, texture and possibly also animation, may come in separate files. How can such data be archived properly? Which non-proprietary formats can or should be accepted? To achieve interoperability and enable annotation, the goal is to have a type of IIIF dissemination. How can this be achieved from the original 3D-models? What open source 3D-viewer should be implemented in web applications? In order to achieve the long-term goal of proper archiving of the original file(s) on the one hand, and the provision of a lightweight, interoperable, viewable and annotatable version of the 3D-model in the web application on the other hand, a process needs to be established that can be automated. I will present our first attempts of establishing such a workflow. References DaSCH Service Platform (DSP): https://www.dasch.swiss/platformcharacteristics IIIF: https://iiif.io/ IIIF 3D Technical Specification Group : https://iiif.io/community/groups/3d/tsg/ IIIF-Prezi3: https://github.com/iiif-prezi/iiif-prezi3