cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Occasional coupling enhances amplitude death in delay-coupled oscillators
Creators: name: Ghosh, Anupam
name: Mondal, Sirshendu
name: Sujith, R. I.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Adaptation and Self-Organizing Systems (nlin.AO)
subject: Chaotic Dynamics (nlin.CD)
subject: FOS: Physical sciences

description: This paper aims to study amplitude death in time delay coupled oscillators using the occasional coupling scheme that implies the intermittent interaction among the oscillators. An enhancement of amplitude death regions (i.e., an increment of the width of the amplitude death regions along the control parameter axis) can be possible using the occasional coupling in a pair of delay-coupled oscillators. Our study starts with coupled limit cycle oscillators (Stuart-Landau) and coupled chaotic oscillators (Rössler). We further examine coupled horizontal Rijke tubes, a prototypical model of thermoacoustic systems. Oscillatory states are highly detrimental to thermoacoustic systems such as combustors. Consequently, a state of amplitude death is always preferred. We employ the on-off coupling (i.e., a square wave function), as an occasional coupling scheme, to these coupled oscillators. On monotonically varying the coupling strength (as a control parameter), we observe an enhancement of amplitude death regions using the occasional coupling scheme compared to the continuous coupling scheme. In order to study the contribution of the occasional coupling scheme, we perform a detailed linear stability analysis and analytically explain this enhancement of the amplitude death region for coupled limit cycle oscillators. We also adopt the frequency ratio of the oscillators and the time delay between the oscillators as the control parameters. Intriguingly, we obtain a similar enhancement of the amplitude death regions using frequency ratio and time delay as the control parameters in the presence of the occasional coupling. Finally, we use a half-wave rectified sinusoidal wave function (motivated by practical reality) to introduce the occasional coupling in time-delay coupled oscillators and get similar results.
description: 12 pages and 16 figures
Environmental Justice: Do Poor and Minority Populations Face More Hazards?
Creators: name: Gray, Wayne B.
name: Shabegian, Ronald J.
name: Wolverton, Ann
name: Gray, Wayne B.
name: Shabegian, Ronald J.
name: Wolverton, Ann
Publisher: name: Unknown
Year: 2010
Subjects: subject: Environmental Economics and Policy
subject: Environmental Justice
subject: regulatory activity
subject: enforcement
subject: political
subject: poor
subject: minority

description: In this paper, we examine the large and expanding area of Environmental Justice (EJ). The research in this area has developed from examining relatively simple comparisons of current demographic characteristics near environmental nuisances to performing multiple regression analysis and considering demographics at the time of siting. One area that has received considerably less attention is the identification of potential mechanisms that could be driving observed EJ correlations. We extend the current literature by examining one possible mechanism: the intensity of regulatory enforcement activity. If regulators pay less attention to the environmental performance of plants located near poor and minority areas, those plants might feel less pressure to pursue pollution abatement projects, increasing environmental hazards in those areas. We perform our analysis on a sample of manufacturing plants located near four large U.S. cities: Los Angeles, Boston, Columbus, and Houston. Our analysis of regulatory activity found little evidence that demographic variables have a significant impact on the allocation of regulatory activity. In particular, regulatory activity does not seem to be less intense in plants located near particular demographic groups. It is true that plants located in minority neighborhoods are inspected less often and face fewer enforcement actions, but these effects are nearly always small and insignificant, and plants located in lower-income areas seem to face (surprisingly) more regulatory activity. In a separate analysis, we also find very little evidence that demographic variables significantly influence pollution emissions. . In summary, the results presented here do not show much evidence to support EJ concerns about either regulatory activity or pollution emissions, at least within the set of plants, pollutants, and time periods covered in our analysis.
Using interactive technology to support reading reflections in literature circles for upper intermediate students
Creators: name: Larson, Kristy Michelle
Publisher: name: The University of British Columbia
Year: 2014

description: This study was designed to examine intermediate student responses to literature written online and with pen and paper. In particular, I looked at student engagement through the use of an online discussion forum. This study was completed in a grade six and seven classroom with twelve participants. I found that while there were few differences in the quality of the literary responses given by students online and on paper, student reported engagement in the discussion forum was very high for a number of reasons, including the social aspect of online discussion forums, the perceived notion of fair talk time, and the ability of students to see the thinking of all their peers.
Poverty Status and IQ Gains from Revising the Dust Lead Hazard Standards: A Method for Evaluating Environmental Justice Implications?
Creators: name: LaPenta, Matthew
name: LaPenta, Matthew
Publisher: name: Unknown
Year: 2010
Subjects: Environmental Economics and Policy

description: ThepurposeofthispaperistooutlineamethodforevaluatingtheEnvironmentalJustice(EJ) implicationsofrevisingthedustleadhazardstandardsforfloors.Forsimplicitythispaperonly addressespopulationsasdefinedbypovertystatus,butthemethodsdescribedcanbeappliedto evaluatedistributionalimplicationsby race,ethnicity,andpopulationsdefinedaccordingto alternativeincomecategories. ThemethodforestimatingIQgainsfromchangesindustlead levelsfollowstheapproachdescribedinEPA’s2008report, TheApproachUsedforEstimating ChangesinChildren’sIQfromLeadDustGeneratedduringRenovation,Repair,andPaintingin ResidencesandChild-occupiedFacilities (EPA2008). Theresultspresentedindicatethat childrenlivingbelowthepovertylevelaremorelikelytolivewheredustleadlevelsexceedthe alternativehazardstandardlevelof10μg/ft2 forfloorsandthereforehavethepotentialtobenefit morefromarevisiontothestandardcomparedtochildrenlivingabovethepovertylevel.
On a wave map equation arising in general relativity
Creators: name: Ringstrom, Hans
Publisher: name: arXiv
Year: 2003
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: This paper has been withdrawn by the author. The paper has been accepted for publication in Communications on Pure and Applied Mathematics.
description: This paper has been withdrawn
The $R$-matrix of the quantum toroidal algebra $U_{q,t}(\overset{..}{gl}_1)$ in the Fock module
Creators: name: Garbali, Alexandr
name: de Gier, Jan
Publisher: name: arXiv
Year: 2020
Subjects: subject: Mathematical Physics (math-ph)
subject: Quantum Algebra (math.QA)
subject: Representation Theory (math.RT)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: We propose a method to compute the $R$-matrix $R$ on a tensor product of Fock modules from coproduct relations in a Hopf algebra. We apply this method to the quantum toroidal algebra $U_{q,t}(\overset{..}{gl}_1)$ for which $R$ is currently not explicitly known. We show that the coproduct relations of $U_{q,t}(\overset{..}{gl}_1)$ reduce to a single elegant equation for $R$. Using the theory of symmetric Macdonald polynomials we show that this equation provides a recursive formula for the matrix elements of $R$.
description: Misprints corrected, references added
Random walks of partons in SU(N_c) and classical representations of color charges in QCD at small x
Creators: name: Jeon, Sangyong
name: Venugopalan, Raju
Publisher: name: arXiv
Year: 2004
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: The effective action for wee partons in large nuclei includes a sum over static color sources distributed in a wide range of representations of the SU(N_c) color group. The problem can be formulated as a random walk of partons in the N_c-1 dimensional space spanned by the Casimirs of SU(N_c). For a large number of sources, k >> 1, we show explicitly that the most likely representation is a classical representation of order O(\sqrt{k}). The quantum sum over representations is well approximated by a path integral over classical sources with an exponential weight whose argument is the quadratic Casimir operator of the group. The contributions of the higher N_c-2 Casimir operators are suppressed by powers of k. Other applications of the techniques developed here are discussed briefly.
description: 51 pages, includes 3 eps files
How Many Times Could You Replicate Polyface Farm? A Schematic Model of Ecosystem Services in Agriculture
Creators: name: Simpson, R. David
name: Simpson, R. David
Publisher: name: Unknown
Year: 2010
Subjects: subject: Environmental Economics and Policy
subject: ecosystem services
subject: conventional agriculture
subject: perfect substitutes
subject: purchased inputs
subject: subsidy

description: There has been considerable recent interest in the idea that farms can produce both food and a variety of ecosystem services. One particularly intriguing notion is that farmers might find it in their own interest to adopt an “ecosystem services” approach to production in preference to a “conventional” approach. In the conventional approach farmers devote substantially all of their land directly to production and purchase a variety of fertilizers, pesticides, and other inputs. In contrast, if farmers preserve a substantial fraction of their land in a more-or-less “natural” condition, or restore it to such a state, the ecosystem services provided by preserved natural systems may obviate the purchase of many inputs. While private adoption of the ecosystem services approach would not result in the optimal provision of ecosystem services, given that some such services generate positive benefits on a broader scale than an individual farmer can appropriate, it is reasonable to regard the conversion of farms from a conventional to an ecosystem services approach to production as a step in the right direction toward more ecologically benign land use. In this paper I develop a simple and schematic model of land use in agriculture. I motivate the model by reference to Polyface Farm, a farm described in Michael Pollan’s 2006 bestseller The Omnivore’s Dilemma. Polyface Farm has adopted an ecosystem service approach: its owner restored more than fourth-fifths of the land he controls to a natural state. In contrast, his neighbors actively farm the great majority of their holdings. I develop a simple model that duplicates the stylized fact that farmers choose between very different production approaches. The model also predicts, however, that farmers who adopt an ecosystem services approach would reduce their production in the same proportion as they reduce the area of land they employ directly in production. This finding has an important implication for policy. While manipulation of agricultural prices or subsidies might induce some farmers to adopt an ecosystem services approach, such a strategy would be self-limiting. When one farmer adopts an ecosystem services approach in preference to the conventional approach she will reduce her output. Prices would rise in response, and the incentive for others to emulate her choice would be reduced.
Recurrence flow measure of nonlinear dependence
Creators: name: Braun, Tobias
name: Kraemer, K. Hauke
name: Marwan, Norbert
Publisher: name: arXiv
Year: 2022
Subjects: subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: Chaotic Dynamics (nlin.CD)
subject: Methodology (stat.ME)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: Couplings in complex real-world systems are often nonlinear and scale-dependent. In many cases, it is crucial to consider a multitude of interlinked variables and the strengths of their correlations to adequately fathom the dynamics of a high-dimensional nonlinear system. We propose a recurrence based dependence measure that quantifies the relationship between multiple time series based on the predictability of their joint evolution. The statistical analysis of recurrence plots (RPs) is a powerful framework in nonlinear time series analysis that has proven to be effective in addressing many fundamental problems, e.g., regime shift detection and identification of couplings. The recurrence flow through an RP exploits artifacts in the formation of diagonal lines, a structure in RPs that reflects periods of predictable dynamics. By using time-delayed variables of a deterministic uni-/multivariate system, lagged dependencies with potentially many time scales can be captured by the recurrence flow measure. Given an RP, no parameters are required for its computation. We showcase the scope of the method for quantifying lagged nonlinear correlations and put a focus on the delay selection problem in time-delay embedding which is often used for attractor reconstruction. The recurrence flow measure of dependence helps to identify non-uniform delays and appears as a promising foundation for a recurrence based state space reconstruction algorithm.
NFANet: A Novel Method for Weakly Supervised Water Extraction from High-Resolution Remote Sensing Imagery
Creators: name: Lu, Ming
name: Fang, Leyuan
name: Li, Muxing
name: Zhang, Bob
name: Zhang, Yi
name: Ghamisi, Pedram
Publisher: name: arXiv
Year: 2022
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: The use of deep learning for water extraction requires precise pixel-level labels. However, it is very difficult to label high-resolution remote sensing images at the pixel level. Therefore, we study how to utilize point labels to extract water bodies and propose a novel method called the neighbor feature aggregation network (NFANet). Compared with pixellevel labels, point labels are much easier to obtain, but they will lose much information. In this paper, we take advantage of the similarity between the adjacent pixels of a local water-body, and propose a neighbor sampler to resample remote sensing images. Then, the sampled images are sent to the network for feature aggregation. In addition, we use an improved recursive training algorithm to further improve the extraction accuracy, making the water boundary more natural. Furthermore, our method utilizes neighboring features instead of global or local features to learn more representative features. The experimental results show that the proposed NFANet method not only outperforms other studied weakly supervised approaches, but also obtains similar results as the state-of-the-art ones.
Calculated de Haas-van Alphen quantities of Ce(M)In5 (M=Co, Rh, and Ir) compounds
Creators: name: Elgazzar, Saad.
name: Opahle, Ingo
name: Hayn, R.
name: Oppeneer, Peter M.
Publisher: name: arXiv
Year: 2004
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We report a critical analysis of the electronic structures and de Haas-van Alphen (dHvA) quantities of the heavy-fermion superconductors CeCoIn$_5$, CeRhIn$_5$, and CeIrIn$_5$. The electronic structures are investigated {\it ab initio} on the basis of full-potential band-structure calculations, adopting both the scalar- and fully relativistic formulations within the framework of the local spin-density approximation (LSDA). In contrast to another recent study, in which a pronounced change of the Fermi surface due to relativistic effects and therefore the importance of relativistic interactions for the superconductivity was claimed, we find only minor relativistic modifications of the band structure in our calculations. The {\it ab initio} calculated dHvA quantities are in good agreement with experimental data for CeCoIn$_5$ and CeIrIn$_5$, when we adopt the delocalized LSDA description for the Ce $4f$ states. For CeRhIn$_5$, however, a better agreement with experiment is obtained when the Ce $4f$ electron is treated as a localized core electron. The implications for an emerging picture of the localization behavior of the $4f$ electron in these materials are discussed. We furthermore compare our calculated dHvA quantities with other recent relativistic calculations and discuss the differences between them.
description: submitted to PRB
A Theory of Migration as a Response to Relative Deprivation
Creators: name: Stark, Oded
name: Wang, You Qiang
name: Stark, Oded
name: Wang, You Qiang
Publisher: name: Unknown
Year: 2000
Subjects: subject: Institutional and Behavioral Economics
subject: International Relations/Trade
subject: migration
subject: social relative deprivation
subject: social welfare
subject: steady state

description: We model migration as a response to relative deprivation. We present a specific configuration of incomes in which the process of migration in response to relative deprivation reaches a steady state. However, for the general configuration of incomes we show that it is impossible to prove the existence of a steady state. We study the social welfare implications of the two cases and show that if individuals are left to pursue their betterment, the resulting state falls short of the best social outcome. We present several implications of the model including federalism and the demand for secession.
Creating Momentum for Nutrition-Sensitive Agriculture: Experiences and Lessons from the Australian Aid Program
Creators: name: Carter, Lucy
name: Peishi, Zalynn
name: Carter, Lucy
name: Peishi, Zalynn
Publisher: name: Unknown
Year: 2018
Subjects: subject: Agricultural and Food Policy
subject: International Development
subject: Nutrition-sensitive agriculture, enabling environment, agricultural development, aid programming

description: Global efforts to improve malnutrition have regained considerable momentum. Enhancing cross-sectoral and multilevel coordination for accelerating progress in reaching global nutrition goals has been a key focus. These efforts have recast how the international development community plans for and implements agriculture policy and programming. While creating and maintaining political momentum for improved nutrition in high-burden countries must be a priority, building the institutional capacity of donor countries to orient investments for enhancing nutrition outcomes is key to this overall vision. From 2013 to 2015, the Australian aid program made significant progress in aligning its agriculture policy and programming to be more nutrition-sensitive. During this period, multiple influences converged to create the conditions for change. This paper takes a retrospective analysis of the shifts that transpired over this period, and the broader policy environment, which made these possible. The important role played by the Food Systems Innovation (FSI) initiative, a partnership between three Australian research and development players in driving this process, is highlighted. The lessons shared here are offered in the spirit of supporting other donors and organizations working in international agriculture development to undertake similar organizational-level action towards greater nutrition-sensitivity. In doing so, agriculture development programs will be better aligned to meet Sustainable Development Goal 2, which seeks to improve nutrition and sustainable agriculture globally. The paper concludes by highlighting the key priorities for sustaining momentum and converting this to results at the ground level.
Discovery of Terahertz Second Harmonic Generation from Lightwave Acceleration of Symmetry--Breaking Nonlinear Supercurrents
Creators: name: Vaswani, C.
name: Sundahl, C.
name: Mootz, M.
name: Mudiyanselage, D. H.
name: Kang, J. H.
name: Yang, X.
name: Cheng, D.
name: Huang, C.
name: Kim, R. H. J.
name: Liu, Z.
name: Luo, L.
name: Perakis, I. E.
name: Eom, C. B.
name: Wang, J.
Publisher: name: arXiv
Year: 2019
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We report terahertz (THz) second harmonic generation (SHG) in superconductors (SC) with inversion symmetric equilibrium states that forbid even-order nonlinearities. Such SHG signal is observed in single-pulse emission by periodic driving with a multi-cycle THz electric field tuned below the SC energy gap and vanishes above the SC critical temperature. We explain the microscopic physics by a dynamical symmetry breaking principle at sub-THz-cycle by using quantum kinetic modeling of the interplay between strong THz-lightwave nonlinearity and pulse propagation. The resulting non-zero integrated pulse area inside the SC drives lightwave nonlinear supercurrents due to sub--cycle Cooper pair acceleration, in contrast to d.c.-biased superconductors, which can be controlled by the bandstructure and the THz pump field.
Lessons from the Past Three Decades
Creators: name: Ponce, Eliseo R.
name: Inocencio, Arlene B.
name: Ponce, Eliseo R.
name: Inocencio, Arlene B.
Publisher: name: Unknown
Year: 2017
Subjects: Research and Development/Tech Change/Emerging Technologies

description: This paper explores the potential for a sustained and mutually beneficial partnership between the Philippine government through the Department of Agriculture (DA) and the International Rice Research Institute (IRRI) in the light of the national and global challenges faced by the Philippine rice sector. In this context, the paper examines the National Rice Program and sector performance over time, and analyzes government spending in connection with the program.
Prevalence of Thyroid Morphology Changes in an Area with Adequate Iodine Intake
Creators: name: Radevska, Tanja
name: Pirnat, Edvard
name: Maša Hribar
name: Urška Blaznik
name: Kušar, Anita
name: Žmitek, Katja
name: Pravst, Igor
name: Gaberšček, Simona
name: Zaletel, Katja
name: Gregorič, Matej
Publisher: name: Zenodo
Year: 2021
Subjects: Prevalence; Thyroid Morphology; Epidemiology; Slovenia

description: Abstract submitted to 34th Annual Congress of the European Association of Nuclear Medicine (October 20-23, 2021)
description: Funding: The Nutrihealth study was part of the research project L3-8213 "Children's and adults' nutrition as a protective or health-risk factor", funded by the Slovenian Research Agency and Ministry of Health of Republic of Slovenia. This work was also supported within the research program P3-0395 (Nutrition and Public health) and project L7-1849 (Challenges in achieving adequate vitamin D status in the adult population). We acknowledge support of Irena Rogelj, head of research project L3-8213.
Embedding an Ethical Mind: Aligning Text-to-Image Synthesis via Lightweight Value Optimization
Creators: name: Wang, Xingqi
name: Yi, Xiaoyuan
name: Xie, Xing
name: Jia, Jia
Publisher: name: arXiv
Year: 2024
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Artificial Intelligence (cs.AI)
subject: Computers and Society (cs.CY)
subject: Machine Learning (cs.LG)
subject: Multimedia (cs.MM)
subject: FOS: Computer and information sciences

description: Recent advancements in diffusion models trained on large-scale data have enabled the generation of indistinguishable human-level images, yet they often produce harmful content misaligned with human values, e.g., social bias, and offensive content. Despite extensive research on Large Language Models (LLMs), the challenge of Text-to-Image (T2I) model alignment remains largely unexplored. Addressing this problem, we propose LiVO (Lightweight Value Optimization), a novel lightweight method for aligning T2I models with human values. LiVO only optimizes a plug-and-play value encoder to integrate a specified value principle with the input prompt, allowing the control of generated images over both semantics and values. Specifically, we design a diffusion model-tailored preference optimization loss, which theoretically approximates the Bradley-Terry model used in LLM alignment but provides a more flexible trade-off between image quality and value conformity. To optimize the value encoder, we also develop a framework to automatically construct a text-image preference dataset of 86k (prompt, aligned image, violating image, value principle) samples. Without updating most model parameters and through adaptive value selection from the input prompt, LiVO significantly reduces harmful outputs and achieves faster convergence, surpassing several strong baselines and taking an initial step towards ethically aligned T2I models.
description: Accepted by ACM Multimedia 2024. The dataset and code can be found at https://github.com/achernarwang/LiVO
Identifiable Acetylene Features Predicted for Young Earth-like Exoplanets with Reducing Atmospheres undergoing Heavy Bombardment
Creators: name: Rimmer, P. B.
name: Ferus, M.
name: Waldmann, I. P.
name: Knížek, A
name: Kalvaitis, D.
name: Ivanek, O.
name: Kubelík, P.
name: Yurchenko, S. N.
name: Burian, T.
name: Dostál, J.
name: Juha, L.
name: Dudžàk, R.
name: Krůs, M.
name: Tennyson, J.
name: Civiš, S.
name: Archibald, A. T.
name: Granville-Willett, A.
Publisher: name: arXiv
Year: 2019
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: The chemical environments of young planets are assumed to be largely influenced by impacts of bodies lingering on unstable trajectories after the dissolution of the protoplanetary disk. We explore the chemical consequences of impacts within the context of reducing planetary atmospheres dominated by carbon monoxide, methane and molecular nitrogen. A terawatt high-power laser was selected in order to simulate the airglow plasma and blast wave surrounding the impactor. The chemical results of these experiments are then applied to a theoretical atmospheric model. The impact simulation results in substantial volume mixing ratios within the reactor of 5% hydrogen cyanide (HCN), 8% acetylene (C$_2$H$_2$), 5% cyanoacetylene (HC$_3$N) and 1% ammonia (NH$_3$). These yields are combined with estimated impact rates for the Early Earth to predict surface boundary conditions for an atmospheric model. We show that impacts might have served as sources of energy that would have led to steady-state surface quantities of 0.4% C$_2$H$_2$, 400 ppm HCN and 40 ppm NH$_3$. We provide simulated transit spectra for an Earth-like exoplanet with this reducing atmosphere during and shortly after eras of intense impacts. We predict that acetylene is as observable as other molecular features on exoplanets with reducing atmospheres that have recently gone through their own `Heavy Bombardments', with prominent features at 3.05 $μ$m and 10.5 $μ$m.
description: 26 pages, 12 figures, 2 tables, accepted for publication by The Astrophysical Journal
Single atom movement with dynamic holographic optical tweezers
Creators: name: Samoylenko, Sergey
name: Lisitsin, Alexey
name: Schepanovich, Danilo
name: Bobrov, Ivan
name: Straupe, Stanislav
name: Kulik, Sergei
Publisher: name: arXiv
Year: 2020
Subjects: subject: Quantum Physics (quant-ph)
subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: We report an experimental implementation of dynamical holographic tweezers for single trapped atoms. The tweezers are realized with dynamical phase holograms displayed on the liquid crystal spatial light modulator. We experimentally demonstrate the possibility to trap and move single rubidium atoms with such dynamic potentials, and study its limitations. Our results suggest that high probability transfer of single atoms in the tweezers may be performed in large steps, much larger then the trap waist. We discuss intensity-flicker in holographic traps and techniques for its suppression. Loss and heating rates in dynamic tweezers are measured and no excess loss or heating is observed in comparison with static traps.
description: 9 pages, 9 figures
Fully kinetic shearing-box simulations of magnetorotational turbulence in 2D and 3D. I. Pair plasmas
Creators: name: Bacchini, Fabio
name: Arzamasskiy, Lev
name: Zhdankin, Vladimir
name: Werner, Gregory R.
name: Begelman, Mitchell C.
name: Uzdensky, Dmitri A.
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Physical sciences

description: The magnetorotational instability (MRI) is a fundamental mechanism determining the macroscopic dynamics of astrophysical accretion disks. In collisionless accretion flows around supermassive black holes, MRI-driven plasma turbulence cascading to microscopic (i.e. kinetic) scales can result in enhanced angular-momentum transport and redistribution, nonthermal particle acceleration, and a two-temperature state where electrons and ions are heated unequally. However, this microscopic physics cannot be captured with standard magnetohydrodynamic (MHD) approaches typically employed to study the MRI. In this work, we explore the nonlinear development of MRI turbulence in a pair plasma, employing fully kinetic Particle-in-Cell (PIC) simulations in two and three dimensions. First, we thoroughly study the axisymmetric MRI with 2D simulations, explaining how and why the 2D geometry produces results that differ substantially from MHD expectations. We then perform the largest (to date) 3D simulations, for which we employ a novel shearing-box approach, demonstrating that 3D PIC models can reproduce the mesoscale (i.e. MHD) MRI dynamics in sufficiently large runs. With our fully kinetic simulations, we are able to describe the nonthermal particle acceleration and angular-momentum transport driven by the collisionless MRI. Since these microscopic processes ultimately lead to the emission of potentially measurable radiation in accreting plasmas, our work is of prime importance to understand current and future observations from first principles, beyond the limitations imposed by fluid (MHD) models. While in this first study we focus on pair plasmas for simplicity, our results represent an essential step toward designing more realistic electron-ion simulations, on which we will focus in future work.
description: Submitted to ApJ
Electrical Contact between an Ultrathin Topological Dirac Semimetal and a Two-Dimensional Material
Creators: name: Cao, Liemao
name: Zhou, Guanghui
name: Wu, Qingyun
name: Yang, Shengyuan A.
name: Yang, Hui Ying
name: Ang, Yee Sin
name: Ang, L. K.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Applied Physics (physics.app-ph)
subject: FOS: Physical sciences

description: Ultrathin films of topological Dirac semimetal, Na$_3$Bi, has recently been revealed as an unusual electronic materials with field-tunable topological phases. Here we investigate the electronic and transport properties of ultrathin Na$_3$Bi as an electrical contact to two-dimensional (2D) metal, i.e. graphene, and 2D semiconductor, i.e. MoS$_2$ and WS$_2$ monolayers. Using combined first-principle density functional theory and nonequilibrium Green's function simulation, we show that the electrical coupling between Na$_3$Bi bilayer thin film and graphene results in a notable interlayer charge transfer, thus inducing sizable $n$-type doping in the Na$_3$Bi/graphene heterostructures. In the case of MoS$_2$ and WS$_2$ monolayers, the lateral Schottky transport barrier is significantly lower than many commonly studied bulk metals, thus unraveling Na$_3$Bi bilayer as a high-efficiency electrical contact material for 2D semiconductors. These findings opens up an avenue of utilizing topological semimetal thin film as electrical contact to 2D materials, and further expands the family of 2D heterostructure devices into the realm of topological materials.
description: 8 pages, 6 figures. Authors' accepted version
Climate Ready- Technologies: Combating Poverty by Raising Productivity in Rainfed Rice Environments in Asia
Creators: name: Manzanilla, Digna O.
name: Singh, Rakesh Kumar
name: Kato, Yoichiro
name: Johnson, David E.
name: Manzanilla, Digna O.
name: Singh, Rakesh Kumar
name: Kato, Yoichiro
name: Johnson, David E.
Publisher: name: Unknown
Year: 2017
Subjects: Research and Development/Tech Change/Emerging Technologies

description: The Consortium for Unfavorable Rice Environments (CURE) has been supporting innovation and technological advances over the past fifteen years to reduce risks, raise productivity, and contribute to poverty reduction in rainfed rice ecosystems in Asia. The Consortium has worked to improve lives in resource-poor rice communities through building a network of networks and linking groups and individuals facing similar constraints. This enables the sharing of information on opportunities for progress. Advances in recent years have enabled the development of stress-tolerant varieties and management options that help farmers reduce risks and raise productivity in areas affected by drought, flooding, or salinity. These have helped improve harvests for smallholder farmers in many parts of Asia.
Collective excitability in highly diluted networks of rotators
Creators: name: Paolini, Gabriele
name: Ciszak, Marzena
name: Marino, Francesco
name: Olmi, Simona
name: Torcini, Alessandro
Publisher: name: arXiv
Year: 2022
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Adaptation and Self-Organizing Systems (nlin.AO)
subject: FOS: Physical sciences

description: We report on collective excitable events in a highly-diluted random network of non-excitable nodes. Excitability arises thanks to a self-sustained local adaptation mechanism that drives the system on a slow time-scale across a hysteretic phase transition involving states with different degrees of synchronization. These phenomena have been investigated for the Kuramoto model with bimodal distribution of the natural frequencies and for the Kuramoto model with inertia and an unimodal frequency distribution. We consider global and local stimulation protocols and characterize the system response for different level of dilution. We compare the results with those obtained in the fully-coupled case showing that such collective phenomena are remarkably robust against network diluteness.
description: 11 pages, 8 Figures
A theorem on the photographic process in Special Relativity. The train paradox revisited
Creators: name: Azreg-Ainou, M.
Publisher: name: arXiv
Year: 2003
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: The purpose of this letter is to show, on the one hand, how the so-called train paradox could be resolved directly without appealing to non-linear Lorentz transformations. The resolution is established in the most general case of curvilinear motion with a variable speed train. On the other hand, we formulate a theorem on the photographic process of two moving objects with relativistic effects.
description: 7 pages, 1 figure
Recently observed $P_c$ as molecular states and possible mixture of $P_c(4457)$
Creators: name: Xu, Hao
name: Li, Qiang
name: Chang, Chao-Hsi
name: Wang, Guo-Li
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Recently observed spectrum of $P_c$ states exhibits a strong link to $Σ_c \bar{D}^{(*)}$ thresholds. In spite of successful molecular interpretations, we still push forward to wonder whether there exist finer structures. Utilizing the effecitve lagrangians respecting heavy quark symmetry and chiral symmetry, as well as instantaneous Bethe-Salpeter equations, we investigate the $Σ_c \bar{D}^{(*)}$ interactions and three $P_c$ states. We confirm that $P_c(4312)$ and $P_c(4440)$ are good candidates of $Σ_c \bar{D}$ and $Σ_c \bar{D}^{*}$ molecules with spin-$\frac12$, respectively. Unlike other molecular calculations, our results indicate $P_c(4457)$ signal might be a mixture of spin-$\frac32$ and spin-$\frac12$ $Σ_c \bar{D}^{*}$ molecules, where the latter one appears to be an excitation of $P_c(4440)$. Therefore we conclude that, confronting three LHCb $P_c$ signals, there may exist not three, but four molecular states.
description: 9 pages, 7 figures
A Low-Cost, Highly Customizable Solution for Position Estimation in Modular Robots
Creators: name: Liu, Chao
name: Tosun, Tarik
name: Yim, Mark
Publisher: name: arXiv
Year: 2022
Subjects: subject: Robotics (cs.RO)
subject: FOS: Computer and information sciences

description: Accurate position sensing is important for state estimation and control in robotics. Reliable and accurate position sensors are usually expensive and difficult to customize. Incorporating them into systems that have very tight volume constraints such as modular robots are particularly difficult. PaintPots are low-cost, reliable, and highly customizable position sensors, but their performance is highly dependent on the manufacturing and calibration process. This paper presents a Kalman filter with a simplified observation model developed to deal with the non-linearity issues that result in the use of low-cost microcontrollers. In addition, a complete solution for the use of PaintPots in a variety of sensing modalities including manufacturing, characterization, and estimation is presented for an example modular robot, SMORES-EP. This solution can be easily adapted to a wide range of applications.
description: 10 pages, 28 figures
Generating series of all modular graph forms from iterated Eisenstein integrals
Creators: name: Gerken, Jan E.
name: Kleinschmidt, Axel
name: Schlotterer, Oliver
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Number Theory (math.NT)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: We study generating series of torus integrals that contain all so-called modular graph forms relevant for massless one-loop closed-string amplitudes. By analysing the differential equation of the generating series we construct a solution for its low-energy expansion to all orders in the inverse string tension $α'$. Our solution is expressed through initial data involving multiple zeta values and certain real-analytic functions of the modular parameter of the torus. These functions are built from real and imaginary parts of holomorphic iterated Eisenstein integrals and should be closely related to Brown's recent construction of real-analytic modular forms. We study the properties of our real-analytic objects in detail and give explicit examples to a fixed order in the $α'$-expansion. In particular, our solution allows for a counting of linearly independent modular graph forms at a given weight, confirming previous partial results and giving predictions for higher, hitherto unexplored weights. It also sheds new light on the topic of uniform transcendentality of the $α'$-expansion.
description: 70+26 pages. Submission includes an ancillary data file. v2: clarified subtlety on modular transformations in section 6.1 and added some four-point data
Detection of magnetohydrodynamic waves by using machine learning
Creators: name: Chen, Fang
name: Samtaney, Ravi
Publisher: name: arXiv
Year: 2022
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: Machine Learning (cs.LG)
subject: Applied Physics (physics.app-ph)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: Nonlinear wave interactions, such as shock refraction at an inclined density interface, in magnetohydrodynamic (MHD) lead to a plethora of wave patterns with myriad wave types. Identification of different types of MHD waves is an important and challenging task in such complex wave patterns. Moreover, owing to the multiplicity of solutions and their admissibility for different systems, especially for intermediate-type MHD shock waves, the identification of MHD wave types is complicated if one solely relies on the Rankine-Hugoniot jump conditions. MHD wave detection is further exacerbated by the unphysical smearing of discontinuous shock waves in numerical simulations. We present two MHD wave detection methods based on a convolutional neural network (CNN) which enables the classification of waves and identification of their locations. The first method separates the output into a regression (location prediction) and a classification problem assuming the number of waves for each training data is fixed. In the second method, the number of waves is not specified a priori and the algorithm, using only regression, predicts the waves' locations and classifies their types. The first fixed output model efficiently provides high precision and recall, the accuracy of the entire neural network achieved is up to 0.99, and the classification accuracy of some waves approaches unity. The second detection model has relatively lower performance, with more sensitivity to the setting of parameters, such as the number of grid cells N_{grid} and the thresholds of confidence score and class probability, etc. The proposed two methods demonstrate very strong potential to be applied for MHD wave detection in some complex wave structures and interactions.
A scalar hyperbolic equation with GR-type non-linearity
Creators: name: Khokhlov, A. M.
name: Novikov, I. D.
Publisher: name: arXiv
Year: 2003
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We study a scalar hyperbolic partial differential equation with non-linear terms similar to those of the equations of general relativity. The equation has a number of non-trivial analytical solutions whose existence rely on a delicate balance between linear and non-linear terms. We formulate two classes of second-order accurate central-difference schemes, CFLN and MOL, for numerical integration of this equation. Solutions produced by the schemes converge to exact solutions at any fixed time $t$ when numerical resolution is increased. However, in certain cases integration becomes asymptotically unstable when $t$ is increased and resolution is kept fixed. This behavior is caused by subtle changes in the balance between linear and non-linear terms when the equation is discretized. Changes in the balance occur without violating second-order accuracy of discretization. We thus demonstrate that a second-order accuracy and convergence at finite $t$ do not guarantee a correct asymptotic behavior and long-term numerical stability. Accuracy and stability of integration are greatly improved by an exponential transformation of the unknown variable.
description: submitted to Class. Quantum Grav
Sarcasm Detection in a Less-Resourced Language
Creators: name: Đoković, Lazar
name: Robnik-Šikonja, Marko
Publisher: name: arXiv
Year: 2024
Subjects: subject: Machine Learning (cs.LG)
subject: Computation and Language (cs.CL)
subject: FOS: Computer and information sciences
subject: I.2.6; I.2.7

description: The sarcasm detection task in natural language processing tries to classify whether an utterance is sarcastic or not. It is related to sentiment analysis since it often inverts surface sentiment. Because sarcastic sentences are highly dependent on context, and they are often accompanied by various non-verbal cues, the task is challenging. Most of related work focuses on high-resourced languages like English. To build a sarcasm detection dataset for a less-resourced language, such as Slovenian, we leverage two modern techniques: a machine translation specific medium-size transformer model, and a very large generative language model. We explore the viability of translated datasets and how the size of a pretrained transformer affects its ability to detect sarcasm. We train ensembles of detection models and evaluate models' performance. The results show that larger models generally outperform smaller ones and that ensembling can slightly improve sarcasm detection performance. Our best ensemble approach achieves an $\text{F}_1$-score of 0.765 which is close to annotators' agreement in the source language.
description: 4 pages, published in the Slovenian Conference on Artificial Intelligence
wiki2rdf: Automatische Extraktion von RDF-Tripeln aus Artikelvolltexten der Wikipedia / wiki2rdf: Automatic extraction of RDF triples from Wikipedia full texts / wiki2rdf: Extraction automatique de triplets RDF à partir de textes intégraux de Wikipédia
Creators: name: Meyer, Alexander
Publisher: name: Humboldt-Universität zu Berlin
Year: 2013
Subjects: subject: Syntaktisches Indexieren
subject: Maschinelles Indexierungsverfahren
subject: Software
subject: Personendokumentation
subject: Nachschlagewerk
subject: syntactical parsing
subject: software
subject: biographic information
subject: wikipedia
subject: 020 Bibliotheks- und Informationswissenschaften
subject: 004 Datenverarbeitung; Informatik
subject: indexation automatique
subject: logiciel
subject: information biographique
subject: wikipédia

description: Im Projekt DBpedia werden unter anderem Informationen aus Wikipedia-Artikeln in RDF-Tripel umgewandelt. Dabei werden jedoch nicht die Artikeltexte berücksichtigt, sondern vorrangig die sogenannten Infoboxen, die Informationen enthalten, die bereits strukturiert sind. Im Rahmen einer Masterarbeit am Institut für Bibliotheks- und Informationswissenschaft der Humboldt-Universität zu Berlin wurde wiki2rdf entwickelt, eine Software zur regelbasierten Extraktion von RDF-Tripeln aus den unstrukturierten Volltexten der Wikipedia. Die Extraktion erfolgt nach Syntax-Parsing mithilfe eines Dependency-Parsers. Exemplarisch wurde wiki2rdf auf 68820 Artikel aus der Kategorie „Wissenschaftler“ der deutschsprachigen Wikipedia angewandt. Es wurden 244563 Tripel extrahiert.
description: DBpedia is a project that among other things extracts RDF statements from articles of Wikipedia. However, it does not exploit full article texts but mainly the so-called infoboxes that contain information that is already structured. As a master thesis at Berlin School of Library and Information Science, wiki2rdf was developed, a tool for rule-based extraction of RDF triples from full unstructured Wikipedia article texts. Extraction is carried out after syntactical parsing using a dependency parser. wiki2rdf has been used for triple extraction from 68820 articles about scientists and humanists (category “Wissenschaftler”) in GermanWikipedia. 244563 triples werde extracted.
description: Le projet DBpedia consiste, parmi d’autres, en la conversion d’articles de Wikipédia en triplets RDF. Toutefois, ne sont pas pris en compte les textes des articles, mais plutôt les encadrés d’information qui contiennent des informations déjà structurées. Wiki2rdf a été développé dans le cadre d’un mémoire de maîtrise à l’Institut de bibliothéconomie et sciences de l’information de l’Université Humboldt de Berlin. Il s’agit d’un logiciel pour l’extraction de triplets RDF de textes intégraux de Wikipédia non structurés. L’extraction se fait grâce à un analyseur de syntaxe et à l’aide d’un analyseur de dépendance. À titre d’exemple, wiki2rdf a été utilisé sur 68.820 articles provenant de la catégorie des « scientifiques » de la Wikipédia germanophone. 244 563 triplets ont ainsi été extraits.