cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Critical properties of a dissipative sandpile model on small world networks
Creators: name: Bhaumik, Himangsu
name: Santra, S. B.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: A dissipative sandpile model (DSM) is constructed and studied on small world networks (SWN). SWNs are generated adding extra links between two arbitrary sites of a two dimensional square lattice with different shortcut densities $ϕ$. Three different regimes are identified as regular lattice (RL) for $ϕ\lesssim 2^{-12}$, SWN for $2^{-12}
description: 14 pages, 16 fugures
Goal-Aware Neural SAT Solver
Creators: name: Ozolins, Emils
name: Freivalds, Karlis
name: Draguns, Andis
name: Gaile, Eliza
name: Zakovskis, Ronalds
name: Kozlovics, Sergejs
Publisher: name: arXiv
Year: 2021
Subjects: subject: Machine Learning (cs.LG)
subject: Artificial Intelligence (cs.AI)
subject: FOS: Computer and information sciences

description: Modern neural networks obtain information about the problem and calculate the output solely from the input values. We argue that it is not always optimal, and the network's performance can be significantly improved by augmenting it with a query mechanism that allows the network at run time to make several solution trials and get feedback on the loss value on each trial. To demonstrate the capabilities of the query mechanism, we formulate an unsupervised (not depending on labels) loss function for Boolean Satisfiability Problem (SAT) and theoretically show that it allows the network to extract rich information about the problem. We then propose a neural SAT solver with a query mechanism called QuerySAT and show that it outperforms the neural baseline on a wide range of SAT tasks.
Simulation of viscoelastic Cosserat rods based on the geometrically exact dynamics of special Euclidean strands
Creators: name: Giusteri, G. G.
name: Miglio, E.
name: Parolini, N.
name: Penati, M.
name: Zambetti, R.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Classical Physics (physics.class-ph)
subject: Numerical Analysis (math.NA)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: We propose a method for the description and simulation of the nonlinear dynamics of slender structures modeled as Cosserat rods. It is based on interpreting the strains and the generalized velocities of the cross sections as basic variables and elements of the special Euclidean algebra. This perspective emerges naturally from the evolution equations for strands, that are one-dimensional submanifolds, of the special Euclidean group. The discretization of the corresponding equations for the three-dimensional motion of a Cosserat rod is performed, in space, by using a staggered grid. The time evolution is then approximated with a semi-implicit method. Within this approach we can easily include dissipative effects due to both the action of external forces and the presence of internal mechanical dissipation. The comparison with results obtained with different schemes shows the effectiveness of the proposed method, which is able to provide very good predictions of nonlinear dynamical effects and shows competitive computation times also as an energy-minimizing method to treat static problems.
description: 17 pages, 9 figures
The result for the grundy number on p4 classes
Creators: name: Mansouri, Ali
name: bouhlel, Mohamed Salim
Publisher: name: arXiv
Year: 2014
Subjects: subject: Discrete Mathematics (cs.DM)
subject: Combinatorics (math.CO)
subject: FOS: Computer and information sciences
subject: FOS: Mathematics

description: Our work becomes integrated into the general problem of the stability of the network ad hoc. Some, works attacked (affected) this problem. Among these works, we find the modelling of the network ad hoc in the form of a graph. We can resume the problem of coherence of the network ad hoc of a problem of allocation of frequency We study a new class of graphs, the fat-extended P4 graphs, and we give a polynomial time algorithm to calculate the Grundy number of the graphs in this class. This result implies that the Grundy number can be found in polynomial time for many graphs
description: 5 pages
Resolving mean-field solutions of dissipative phase transitions using permutational symmetry
Creators: name: Jo, Minjae
name: Jhun, Bukyoung
name: Kahng, B.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Phase transitions in dissipative quantum systems have been investigated using various analytical approaches, particularly in the mean-field (MF) limit. However, analytical results often depend on specific methodologies. For instance, Keldysh formalism shows that the dissipative transverse Ising (DTI) model exhibits a discontinuous transition at the upper critical dimension, $d_c= 3$, whereas the fluctuationless MF approach predicts a continuous transition in infinite dimensions ($d_\infty$). These two solutions cannot be reconciled because the MF solutions above $d_c$ should be identical. This necessitates a numerical verification. However, numerical studies on large systems may not be feasible because of the exponential increase in computational complexity as $\mathcal{O}(2^{2N})$ with system size $N$. Here, we note that because spins can be regarded as being fully connected at $d_\infty$, the spin indices can be permutation invariant, and the number of quantum states can be considerably contracted with the computational complexity $\mathcal{O}(N^3)$. The Lindblad equation is transformed into a dynamic equation based on the contracted states. Applying the Runge--Kutta algorithm to the dynamic equation, we obtain all the critical exponents, including the dynamic exponent $z\approx 0.5$. Moreover, since the DTI model has $\mathbb{Z}_2$ symmetry, the hyperscaling relation has the form $2β+γ=ν(d+z)$, we obtain the relation $d_c+z=4$ in the MF limit. Hence, $d_c\approx 3.5$; thus, the discontinuous transition at $d=3$ cannot be treated as an MF solution. We conclude that the permutation invariance at $d_\infty$ can be used effectively to check the validity of an analytic MF solution in quantum phase transitions.
description: 12 pages, 8 figures
STRUCTURE-ACTIVITY RELATIONSHIPS OF A SMALL MOLECULE INHIBITOR OF AMINOGLYCOSIDE 6'-N ACETYLTRANSFERASE TYPE Ib [AAC(6')-Ib]
Creators: name: Rocha, Kenneth
Publisher: name: Zenodo
Year: 2021
Subjects: AAC(6')-IB
compounds
aminoglycoside
SAR
antimicrobial resistance

description: Aminoglycosides are a standard treatment for gram-negative bacterial infections but, their efficacy is declining due to the rise and dissemination of antimicrobial resistance. Resistance to aminoglycosides is caused mainly by aminoglycoside modifying enzymes, with aminoglycoside (6’)-N-acetyltransferase type Ib [AAC(6')-Ib] being the most clinically relevant in Gram-negative pathogens. This enzyme catalyzes the inactivation of aminoglycosides by transferring an acetyl group from acetyl CoA to the 6’ amino group of the antibiotic molecule. A strategy to combat this issue is the development of inhibitors of AAC(6’)-Ib. Using mixture-based combinatorial libraries, the scaffold ranking approach and the positional scanning strategy, inhibitors were searched for and identified. A compound was identified and found to be potent against AAC(6')-Ib, potentiated the activity of amikacin against three resistant bacteria-harboring aac(6')-Ib and improved the survival of Galleria mellonella infected with Klebsiella pneumoniae and Acinetobacter baumannii strains harboring aac(6’)-Ib. To further develop this potential inhibitor, the structure-activity relationship approach was applied to a series of experiments involving analog of this inhibitor at five R diversity positions of the compound and were tested for the ability to inhibit AAC(6’)-Ib in vitro and to potentiate the antimicrobial action of amikacin against an Acinetobacter baumannii strain harboring aac(6’)-Ib. Most changes were found to either diminish or have negligible effects on the performance of the inhibitor, except at R5 diversity position which didn’t result in a significant reduction in performance. In addition, compound 19 exhibited antimicrobial properties that may warrant further investigation. In the end, a better understanding of the inhibitor was achieved; however, more work is needed for the continued development of this compound.
Hierarchical contagions in the interdependent financial network
Creators: name: Barnett, William A.
name: Wang, Xue
name: Xu, Hai-Chuan
name: Zhou, Wei-Xing
Publisher: name: arXiv
Year: 2021
Subjects: subject: Risk Management (q-fin.RM)
subject: FOS: Economics and business

description: We derive the default cascade model and the fire-sale spillover model in a unified interdependent framework. The interactions among banks include not only direct cross-holding, but also indirect dependency by holding mutual assets outside the banking system. Using data extracted from the European Banking Authority, we present the interdependency network composed of 48 banks and 21 asset classes. For the robustness, we employ three methods, called $\textit{Anan}$, $\textit{Hała}$ and $\textit{Maxe}$, to reconstruct the asset/liability cross-holding network. Then we combine the external portfolio holdings of each bank to compute the interdependency matrix. The interdependency network is much denser than the direct cross-holding network, showing the complex latent interaction among banks. Finally, we perform macroprudential stress tests for the European banking system, using the adverse scenario in EBA stress test as the initial shock. For different reconstructed networks, we illustrate the hierarchical cascades and show that the failure hierarchies are roughly the same except for a few banks, reflecting the overlapping portfolio holding accounts for the majority of defaults. We also calculate systemic vulnerability and individual vulnerability, which provide important information for supervision and relevant management actions.
description: 18 pages, 4 figures, and 8 tables
Intent Disentanglement and Feature Self-supervision for Novel Recommendation
Creators: name: Qian, Tieyun
name: Liang, Yile
name: Li, Qing
name: Ma, Xuan
name: Sun, Ke
name: Peng, Zhiyong
Publisher: name: arXiv
Year: 2021
Subjects: subject: Information Retrieval (cs.IR)
subject: FOS: Computer and information sciences

description: One key property in recommender systems is the long-tail distribution in user-item interactions where most items only have few user feedback. Improving the recommendation of tail items can promote novelty and bring positive effects to both users and providers, and thus is a desirable property of recommender systems. Current novel recommendation studies over-emphasize the importance of tail items without differentiating the degree of users' intent on popularity and often incur a sharp decline of accuracy. Moreover, none of existing methods has ever taken the extreme case of tail items, i.e., cold-start items without any interaction, into consideration. In this work, we first disclose the mechanism that drives a user's interaction towards popular or niche items by disentangling her intent into conformity influence (popularity) and personal interests (preference). We then present a unified end-to-end framework to simultaneously optimize accuracy and novelty targets based on the disentangled intent of popularity and that of preference. We further develop a new paradigm for novel recommendation of cold-start items which exploits the self-supervised learning technique to model the correlation between collaborative features and content features. We conduct extensive experimental results on three real-world datasets. The results demonstrate that our proposed model yields significant improvements over the state-of-the-art baselines in terms of accuracy, novelty, coverage, and trade-off.
Recovering energy from waste: an overview of presented business cases and models
Creators: name: Rao, Krishna C.
name: Gebrezgabher, Solomie
name: Rao, Krishna C.
name: Gebrezgabher, Solomie
Publisher: name: Unknown
Year: 2018
Subjects: subject: Agribusiness
subject: Financial Economics
subject: Research and Development/Tech Change/Emerging Technologies
subject: Energy recovery
subject: Energy generation
subject: Resource recovery
subject: Business models
subject: Sustainable development
subject: Case studies

description: In Otoo, Miriam; Drechsel, Pay (Eds.). Resource recovery from waste: business models for energy, nutrient and water reuse in low- and middle-income countries. Oxon, UK: Routledge - Earthscan
ReLAX: Reinforcement Learning Agent eXplainer for Arbitrary Predictive Models
Creators: name: Chen, Ziheng
name: Silvestri, Fabrizio
name: Wang, Jia
name: Zhu, He
name: Ahn, Hongshik
name: Tolomei, Gabriele
Publisher: name: arXiv
Year: 2021
Subjects: subject: Machine Learning (cs.LG)
subject: Artificial Intelligence (cs.AI)
subject: FOS: Computer and information sciences

description: Counterfactual examples (CFs) are one of the most popular methods for attaching post-hoc explanations to machine learning (ML) models. However, existing CF generation methods either exploit the internals of specific models or depend on each sample's neighborhood, thus they are hard to generalize for complex models and inefficient for large datasets. This work aims to overcome these limitations and introduces ReLAX, a model-agnostic algorithm to generate optimal counterfactual explanations. Specifically, we formulate the problem of crafting CFs as a sequential decision-making task and then find the optimal CFs via deep reinforcement learning (DRL) with discrete-continuous hybrid action space. Extensive experiments conducted on several tabular datasets have shown that ReLAX outperforms existing CF generation baselines, as it produces sparser counterfactuals, is more scalable to complex target models to explain, and generalizes to both classification and regression tasks. Finally, to demonstrate the usefulness of our method in a real-world use case, we leverage CFs generated by ReLAX to suggest actions that a country should take to reduce the risk of mortality due to COVID-19. Interestingly enough, the actions recommended by our method correspond to the strategies that many countries have actually implemented to counter the COVID-19 pandemic.
Multitask Learning for Scalable and Dense Multilayer Bayesian Map Inference
Creators: name: Gan, Lu
name: Kim, Youngji
name: Grizzle, Jessy W.
name: Walls, Jeffrey M.
name: Kim, Ayoung
name: Eustice, Ryan M.
name: Ghaffari, Maani
Publisher: name: arXiv
Year: 2021
Subjects: subject: Robotics (cs.RO)
subject: FOS: Computer and information sciences

description: This article presents a novel and flexible multitask multilayer Bayesian mapping framework with readily extendable attribute layers. The proposed framework goes beyond modern metric-semantic maps to provide even richer environmental information for robots in a single mapping formalism while exploiting intralayer and interlayer correlations. It removes the need for a robot to access and process information from many separate maps when performing a complex task, advancing the way robots interact with their environments. To this end, we design a multitask deep neural network with attention mechanisms as our front-end to provide heterogeneous observations for multiple map layers simultaneously. Our back-end runs a scalable closed-form Bayesian inference with only logarithmic time complexity. We apply the framework to build a dense robotic map including metric-semantic occupancy and traversability layers. Traversability ground truth labels are automatically generated from exteroceptive sensory data in a self-supervised manner. We present extensive experimental results on publicly available datasets and data collected by a 3D bipedal robot platform and show reliable mapping performance in different environments. Finally, we also discuss how the current framework can be extended to incorporate more information such as friction, signal strength, temperature, and physical quantity concentration using Gaussian map layers. The software for reproducing the presented results or running on customized data is made publicly available.
COLLABORATIVE TEACHING: CO-TEACHING  ENGLISH LANGUAGE LEARNERS WITHIN ENGLISH-ONLY CLASSROOMS
Creators: name: Debro-Harris, Ruth Carla
Publisher: name: Zenodo
Year: 2021
Subjects: English language learners
co-teaching
growth mindset
fixed mindset
English-only students

description: The instructional method of collaborative teaching has recently been proposed to meet the challenging needs of English language learners. However, research on the academic effectiveness of co-teaching is sparse. This study sought to address this research gap through an experimental design to evaluate the impact of collaborative instruction in a co-taught environment with English language learners and English-only students. In addition, a semistructured interview was conducted with a teacher engaged in co-teaching to assess their perception of collaborative instruction, and a questionnaire was administered to explore the experiences of students exposed to a co-taught environment. Differences in the co-teaching mindset of students who received collaborative instruction and those who did not were also compared. Results suggested that co-teaching has a positive influence on the reading performance of learners, with students introduced to a co-taught environment reporting higher Dynamic Indicators of Basic Early Literacy Skills scores than students exposed to solo instruction. Similarly, the teacher and students who were engaged in co-teaching held particularly positive attitudes toward this teaching method. Finally, both students who received collaborative instruction and those who did not display a growth mindset toward co-teaching. Consequently, collaborative instruction is considered a promising intervention, and implications along with recommendations are discussed.
The CHSH-type inequalities for infinite-dimensional quantum systems
Creators: name: Guo, Yu
Publisher: name: arXiv
Year: 2013
Subjects: subject: Quantum Physics (quant-ph)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: By establishing CHSH operators and CHSH-type inequalities, we show that any entangled pure state in infinite-dimensional systems is entangled in a $2\otimes2$ subspace. We find that, for infinite-dimensional systems, the corresponding properties are similar to that of the two-qubit case: (i) The CHSH-type inequalities provide a sufficient and necessary condition for separability of pure states; (ii) The CHSH operators satisfy the Cirel'son inequalities; (iii) Any state which violates one of these Bell inequalities is distillable.
description: 9 pages. arXiv admin note: text overlap with arXiv:1006.3557 by other authors
Study of a bi-axial (KTP) crystal using Double Stokes Mueller Polarimetry
Creators: name: Shaji, Chitra
name: B, Sruthil Lal S
name: Sharan, Alok
Publisher: name: arXiv
Year: 2021
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: We report the significance of the double Stokes Mueller polarimetry (DSMP) technique, to characterize a large size (3 X 3 X 5mm) KTP (Potassium titanyl phosphate) crystal. The crystal undergoes second harmonic generation with type II phase matching. The study of standard KTP crystal using the DSMP technique helps to validate the efficiency of this technique. We were able to extract the crystal's double Mueller matrix, the relative contribution of the susceptibility tensor components, the phase difference between the susceptibility tensor components, etc. We could determine the crystal axes orientation using this optical technique, which was not possible through a single crystal X-Ray diffraction technique for such a large size crystal for which both optic axes and crystallographic axes are the same. Axes direction determined from polarization microscope measurements and Laue diffraction measurements on KTP crystal is compared with those obtained from DSMP measurements.
description: 22 pages,11 figures
Superposition in Measuring Apparatus: A Thought Experiment
Creators: name: KS, Vishwas
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The measurement problem in quantum mechanics arises from the apparent collapse of a superposition state to a definite outcome when a measurement is made. Although treating the measuring apparatus as a classical system has been a successful approach in explaining quantum phenomena, it raises fundamental questions about the nature of measurement and the validity of wave function collapse. In this paper, we discuss a thought experiment that explores superposition in the measuring apparatus when it is treated as a quantum system. The experiment uses the Hong-Ou-Mandel effect in a two-photon interference setup, and its outcome is indicated by the coincidence count. Specifically, a zero count implies the existence of superposition, while a non-zero count indicates a wave function collapse. The discussions provide insight into the measurement problem, particularly regarding wave function collapse and nested measurement, and highlight the importance of indistinguishability to it. It provides a framework that probes the exact conditions necessary for a wave function collapse to happen.
description: 9 pages, 4 figures
Deliverable 5.6 Final Training Materials
Creators: name: Madden, Frances
name: Dohna, Tina
name: van Horik, René
name: Lavasa, Artemis
name: Dasler, Robin
Publisher: name: Zenodo
Year: 2020
Subjects: Persistent Identifiers
Training

description: This report provides an overview of the training materials created within FREYA from the beginning of the project to Month 33 (August 2020).
Convergence analysis for forward and inverse problems in singularly perturbed time-dependent reaction-advection-diffusion equations
Creators: name: Chaikovskii, Dmitrii
name: Zhang, Ye
Publisher: name: arXiv
Year: 2021
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics

description: In this paper, by employing the asymptotic expansion method, we prove the existence and uniqueness of a smoothing solution for a time-dependent nonlinear singularly perturbed partial differential equation (PDE) with a small-scale parameter. As a by-product, we obtain an approximate smooth solution, constructed from a sequence of reduced stationary PDEs with vanished high-order derivative terms. We prove that the accuracy of the constructed approximate solution can be in any order of this small-scale parameter in the whole domain, except a negligible transition layer. Furthermore, based on a simpler link equation between this approximate solution and the source function, we propose an efficient algorithm, called the asymptotic expansion regularization (AER), for solving nonlinear inverse source problems governed by the original PDE. The convergence-rate results of AER are proven, and the a posteriori error estimation of AER is also studied under some a priori assumptions of source functions. Various numerical examples are provided to demonstrate the efficiency of our new approach.
Stability and plasticity of silicon nanowires: the role of wire perimeter
Creators: name: Justo, J. . F.
name: Menezes, R. D.
name: Assali, L. V. C.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We investigated the properties of stability and plasticity of silicon nanowires using molecular dynamics simulations. We considered nanowires with <100>, <110> and <112> growth directions with several diameters and surface facet configurations. We found that the wire perimeter, and not the wire diameter, is the meaningful dimensional parameter. As a result, the surface facets play a central role on the nanowire energy, that follows a universal scaling law. Additionally, we have computed the response of a silicon nanowire to external load. The results were compared to available experimental and ab initio data.
description: 13 pages, 4 figures
Tunable power law in the desynchronization events of coupled chaotic electronic circuits
Creators: name: Oliveira, Gilson F. de
name: Cavalcante, Hugo L. D. de Souza
name: di Lorenzo, Orlando
name: Chevrollier, Martine
name: de Silans, Thierry Passerat
name: Oriá, Marcos
Publisher: name: arXiv
Year: 2013
Subjects: subject: Chaotic Dynamics (nlin.CD)
subject: FOS: Physical sciences

description: We study the statistics of the amplitude of the synchronization error in chaotic electronic circuits coupled through linear feedback. Depending on the coupling strength, our system exhibits three qualitatively different regimes of synchronization: weak coupling yields independent oscillations; moderate to strong coupling produces a regime of intermittent synchronization known as attractor bubbling; and stronger coupling produces complete synchronization. In the regime of moderate coupling, the probability distribution for the sizes of desynchronization events follows a power law, with an exponent that can be adjusted by changing the coupling strength. Such power-law distributions are interesting, as they appear in many complex systems. However, most of the systems with such a behavior have a fixed value for the exponent of the power law, while here we present an example of a system where the exponent of the power law is easily tuned in real time.
description: 15 pages, 6 figures
IN THE DIRECTION OF TRUE EQUITY AND INCLUSION: SERVING STUDENTS WITH DISABILITIES UNDER NEW COMMUNITY COLLEGE FRAMEWORKS
Creators: name: Morales Gutierrez, Connie
Publisher: name: Zenodo
Year: 2022
Subjects: disabled students
guided pathways
A. B. 705
campus culture
inclusion

description: The purpose of this qualitative study was to demonstrate how community college disability services program administrators were involved in implementation of guided pathways and A.B. 705. In addition, the study addresses the level of involvement that disability services staff had been able to achieve, and methods staff used to insert themselves in their college’s implementation of the new frameworks. The level to which students living with a disability and attending a California Community College were considered in these designs and implementation both at a systems level by the California Community College Chancellors Office, and at local community colleges is explored.

Participants shared that the campus culture on their campus impacted the degree of their invitation to participate in planning and design, and the consideration of students with a disability. Their personal experiences varied, with some participating in the work, and others advocating, and showing up to participate despite not being invited. All participants shared the same commitment to ensuring accessibility and support for students they serve. 

Findings will inform policy, advocacy at local and state levels, and inclusion for students living with a disability to be considered in the design and implementation of new community college frameworks moving forward. Enhanced advocacy, training, and data collection will also support these efforts to ensure a move towards true, equity, and inclusion for our most vulnerable and disproportionality impacted students.
Morawetz estimates without relative degeneration and exponential decay on Schwarzschild-de Sitter spacetimes
Creators: name: Mavrogiannis, Georgios
Publisher: name: arXiv
Year: 2021
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Mathematical Physics (math-ph)
subject: Analysis of PDEs (math.AP)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: We use a novel physical space method to prove relatively non-degenerate integrated energy estimates for the wave equation on subextremal Schwarzschild-de Sitter spacetimes with parameters $(M,Λ)$. These are integrated decay statements whose bulk energy density, though degenerate at highest order, is everywhere comparable to the energy density of the boundary fluxes. As a corollary, we prove that solutions of the wave equation decay exponentially on the exterior region. The main ingredients are a previous Morawetz estimate of Dafermos-Rodnianski and an additional argument based on commutation with a vector field which can be expressed in the form $r\sqrt{1-\frac{2M}{r}-\fracΛ{3}r^2}\frac{\partial}{\partial r}$, where $\partial_r$ here denotes the coordinate vector field corresponding to a well chosen system of hyperboloidal coordinates. Our argument gives exponential decay also for small first order perturbations of the wave operator. In the limit $Λ=0$, our commutation corresponds to the one introduced by Holzegel-Kauffman.
description: 29 pages, 4 figures
Time- and Space-Varying Neutrino Mass Matrix from Soft Topological Defects
Creators: name: Dvali, Gia
name: Funcke, Lena
name: Vachaspati, Tanmay
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We study the formation and evolution of topological defects that arise in the post-recombination phase transition predicted by the gravitational neutrino mass model in [Dvali, Funcke, Phys. Rev. D 93, 113002 (2016)]. In the transition, global skyrmions, monopoles, strings, and domain walls form due to the spontaneous breaking of the neutrino flavor symmetry. These defects are unique in their softness and origin; as they appear at a very low energy scale, they only require Standard Model particle content, and they differ fundamentally depending on the Majorana or Dirac nature of the neutrinos. One of the observational signatures is the time dependence and space dependence of the neutrino mass matrix, which could be observable in future neutrino experiments. Already existing data rule out parts of the parameter space in the Majorana case. The detection of this effect could shed light onto the open question of the Dirac versus Majorana neutrino nature.
description: 10 pages, v2: updated to match journal version
3d transition metal impurities in diamond: electronic properties and chemical trends
Creators: name: Assali, L. V. C.
name: Machado, W. V. M.
name: Justo, J. F.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: First principles calculations have been used to investigate the trends on the properties of isolated 3d transition metal impurities (from Sc to Cu) in diamond. Those impurities have small formation energies in the substitutional or double semi-vacancy sites, and large energies in the interstitial one. Going from Sc to Cu, the 3d-related energy levels in the bandgap move from the top of the bandgap toward the valence band in all three sites. Trends in electronic properties and transition energies of the impurities, in the substitutional or interstitial sites, are well described by a simple microscopic model considering the electronic occupation of the 3d-related levels. On the other hand, for the impurities in the double semi-vacancy site, there is a weak interaction between the divacancy- and the 3d-related orbitals, resulting in in vacancy- and 3d-related levels in the materials bandgap.
description: 19 pages, 6 figures
On superstatistics and black hole quasinormal modes
Creators: name: Martínez-Merino, Aldo
name: Sabido, M.
Publisher: name: arXiv
Year: 2021
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: It is known that using Boltzmann-Gibbs statistics, Bekenstein-Hawking entropy $S_{HB}$, and the quasinormal modes of black holes, one finds that the lowest value of spin is $j_{min}=1$. In this paper, we determine $j_{min}$, using non-extensive entropies that depend only on the probability (known as Obregon's entropies and have been derived from superstatistics). We also calculate $j_{min}$ for a set of non-extensive entropies that have free parameters and are written in terms of $S_{BH}$. We find that $j_{min}$ depends on the area and the non-extensive parameter. For the non-extensive entropies that only depend on the probability, we find that the modification is only present for micro black holes. For classical black holes the results are the same as for the Boltzmann-Gibbs statistics.
description: 9 pages, 5 figures. Matches published version
An Efficient Coarse Grid Projection Method for Quasigeostrophic Models of Large-Scale Ocean Circulation
Creators: name: San, Omer
name: Staples, Anne E.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: This paper puts forth a coarse grid projection (CGP) multiscale method to accelerate computations of quasigeostrophic (QG) models for large scale ocean circulation. These models require solving an elliptic sub-problem at each time step, which takes the bulk of the computational time. The method we propose here is a modular approach that facilitates data transfer with simple interpolations and uses black-box solvers for solving the elliptic sub-problem and potential vorticity equations in the QG flow solvers. After solving the elliptic sub-problem on a coarsened grid, an interpolation scheme is used to obtain the fine data for subsequent time stepping on the full grid. The potential vorticity field is then updated on the fine grid with savings in computational time due to the reduced number of grid points for the elliptic solver. The method is applied to both single layer barotropic and two-layer stratified QG ocean models for mid-latitude oceanic basins in the beta plane, which are standard prototypes of more realistic ocean dynamics. The method is found to accelerate these computations while retaining the same level of accuracy in the fine-resolution field. A linear acceleration rate is obtained for all the cases we consider due to the efficient linear-cost fast Fourier transform based elliptic solver used. We expect the speed-up of the CGP method to increase dramatically for versions of the method that use other, suboptimal, elliptic solvers, which are generally quadratic cost. It is also demonstrated that numerical oscillations due to lower grid resolutions, in which the Munk scales are not resolved adequately, are effectively eliminated with CGP method.
description: International Journal for Multiscale Computational Engineering, 2013. arXiv admin note: substantial text overlap with arXiv:1212.0140, arXiv:1212.0922, arXiv:1104.2730
TRACKING MAGMA MIXING AND FRACTIONATION IN THE TUOLUMNE INTRUSIVE COMPLEX WITH K-FELDSPAR MEGACRYSTS
Creators: name: Chen (Ye), Julia
Publisher: name: Zenodo
Year: 2023
Subjects: geochemistry
geochronology
magma
megacrysts
mixing
Tuolumne

description: A pluton grows by the incremental accumulation of magmas but the extent of magma mixing, and the size of the magma bodies are not well understood, as in the case of the Tuolumne Intrusive Complex (TIC), a Cretaceous nested pluton that comprises the Kuna Crest Granodiorite, the equigranular Half Dome Granodiorite (eHD), porphyritic Half Dome Granodiorite (pHD) and the Cathedral Peak Granodiorite (CP). Hypotheses tested in this study are the size of K-feldspar megacrysts is proportional to crystallization time and depends on magma mixing, and the extent of mixing in TIC ranged from eHD to CP. To test these hypotheses, this project conducted fieldwork, petrography, K-feldspar trace element geochemistry, and CA-ID-TIMS-TEA U-Pb geochronology and trace element geochemistry of zircons included in growth zones of K-feldspar megacrysts. Minor changes in Ba, Ca, Sr, Rb, and Pb concentrations from core to rim of the outer pHD, outer pHD/CP, and CP megacrysts revealed magma mixing, whereas the decreasing Ba, Ca, and Sr concentrations and the increasing Rb and Pb concentrations from core to rim and the sequential trend between core, mantle, and rim in the inner pHD and inner pHD/CP megacrysts revealed fractionation and magma mixing. U-Pb zircon ages of cores and rims of pHD and CP megacrysts and groundmass revealed minimum ages to be of pHD and CP ages, respectively. However, in pHD/CP megacrysts, the cores have pHD and CP ages while the rims and groundmass have CP ages, indicating magma mixing. These results show that at the height of magmatism, TIC was an interconnected magma plumbing system with fresh magma intruded and mixed heterogeneously with pre-existing magmas, producing mixing- and fractionation-dominated zones. This study concludes that although the large sizes of K-feldspar megacrysts likely depended on magmatism, which occurred from eHD to CP, the size of the megacrysts is not proportional with time.
Bibliographie Walter Künneth zum 65. Geburtstag am 1. Januar 1966
Creators: name: Kopfermann, Wolfram
Publisher: name: Lutherische Kirche in der Welt
Year: 1970

description: Lutherische Kirche in der Welt, Bd. 14 (1967): Jahrbuch des Martin-Luther-Bundes, Band 14
title: Herbicide efficacy for common ragweed control after defoliation (Slovenia)
Creators: name: Leskovšek, Robert
name: Simončič, Andrej
name: Lešnik, Mario
Publisher: name: Julius Kühn-Institut
Year: 2016

description: Julius-Kühn-Archiv, Nr. 455 (2016): HALT Ambrosia - final project report and general publication of project findings
CT4Rec: Simple yet Effective Consistency Training for Sequential Recommendation
Creators: name: Liu, Chong
name: Liu, Xiaoyang
name: Zheng, Rongqin
name: Zhang, Lixin
name: Liang, Xiaobo
name: Li, Juntao
name: Wu, Lijun
name: Zhang, Min
name: Lin, Leyu
Publisher: name: arXiv
Year: 2021
Subjects: subject: Information Retrieval (cs.IR)
subject: FOS: Computer and information sciences

description: Sequential recommendation methods are increasingly important in cutting-edge recommender systems. Through leveraging historical records, the systems can capture user interests and perform recommendations accordingly. State-of-the-art sequential recommendation models proposed very recently combine contrastive learning techniques for obtaining high-quality user representations. Though effective and performing well, the models based on contrastive learning require careful selection of data augmentation methods and pretext tasks, efficient negative sampling strategies, and massive hyper-parameters validation. In this paper, we propose an ultra-simple alternative for obtaining better user representations and improving sequential recommendation performance. Specifically, we present a simple yet effective \textbf{C}onsistency \textbf{T}raining method for sequential \textbf{Rec}ommendation (CT4Rec) in which only two extra training objectives are utilized without any structural modifications and data augmentation. Experiments on three benchmark datasets and one large newly crawled industrial corpus demonstrate that our proposed method outperforms SOTA models by a large margin and with much less training time than these based on contrastive learning. Online evaluation on real-world content recommendation system also achieves 2.717\% improvement on the click-through rate and 3.679\% increase on the average click number per capita. Further exploration reveals that such a simple method has great potential for CTR prediction. Our code is available at \url{https://github.com/ct4rec/CT4Rec.git}.
Colossal Thermoelectric Power Factor in K$_{7/8}$RhO$_2$
Creators: name: Saeed, Y.
name: Singh, N.
name: Schwingenschlögl, U.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We discuss the thermoelectric and optical properties of layered K$_{x}$RhO$_{2}$ (\emph{x} = 1/2 and 7/8) in terms of the electronic structure determined by first principles calculations as well as Boltzmann transport theory. Our optimized lattice constants differ significantly from the experiment, but result in optical and transport properties close to the experiment. The main contribution to the optical spectra are due to intra and inter-band transitions between the Rh 4\emph{d} and O 2\emph{p} states. We find a similar power factor for pristine K$_{x}$RhO$_{2}$ at low and high cation concentartions. Our transport results of hydrated K$_{x}$RhO$_{2}$ at room temperature show highest value of the power factor among the hole-type materials. Specially at 100 K, we obtain a value of 3$\times$10$^{-3}$ K$^{-1}$ for K$_{7/8}$RhO$_{2}$, which is larger than that of Na$_{0.88}$CoO$_{2}$ {[}M. Lee \emph{et al}., Nat. Mater. 5, 537 (2006){]}. In general, the electronic and optical properties of K$_{x}$RhO$_{2}$ are similar to Na$_{x}$CoO$_{2}$ with enhanced transport properties in the hydrated phase.
Generation and entanglement study of generalized N-mode single photon perfect W-states
Creators: name: Swain, Manoranjan
name: Selvan, M. Karthick
name: Rai, Amit
name: Panigrahi, Prasanta K.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We consider single photon realization of generalized N-qubit perfect W-states which are suitable for perfect teleportation and superdense coding. We propose schemes to generate generalized N-mode single photon perfect W-states and derive entanglement conditions which for single photon states require finding fidelity with generalized N-mode single photon perfect W-states and hence more suitable to detect the genuine entanglement of generalized perfect W-states. Based on the evolution of single photon wavefunction in scalable integrated photonic lattices, we present schemes for the preparation of generalized N-mode single photon perfect W-states at desired propagation distance. The integrated waveguide structures can precisely be fabricated, offer low photon propagation losses and can be integrated on a chip. We consider both planar and ring type waveguide structures for state generation. We derive set of generalized entanglement conditions using the sum uncertainty relations of generalized su(2) algebra operators. We show that any given genuinely entangled N-mode single photon state is a squeezed state of a specific su(2) algebra operator and can be expressed as superposition of a pair of orthonormal generalized N-mode single photon perfect W-states which are eigenstates of that specific su(2) algebra operator. Within the single photon subspace, the eigendecomposition of su(2) algebra operators reduces the generalized entanglement condition to a simplified single photon separability condition. In order to verify the entanglement of given genuinely entangled N-mode single photon state using this condition one has to find the difference between the state fidelities with suitably chosen pair of orthonormal generalized N-mode single photon perfect W-states. Finally, we propose an experimental scheme to verify the entanglement using the proposed conditions...
description: 12 pages, 4 figures
Differential Rotation in a 3D Simulation of Oxygen Shell Burning
Creators: name: McNeill, Lucy O.
name: Müller, Bernhard
Publisher: name: arXiv
Year: 2021
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We study differential rotation in late-stage shell convection in a 3D hydrodynamic simulation of a rapidly rotating $16M_\odot$ helium star with a particular focus on the convective oxygen shell. We find that the oxygen shell develops a quasi-stationary pattern of differential rotation that is neither described by uniform angular velocity as assumed in current stellar evolution models of supernova progenitors, nor by uniform specific angular momentum. Instead, the oxygen shell develops a positive angular velocity gradient with faster rotation at the equator than at the pole by tens of percent. We show that the angular momentum transport inside the convection zone is not adequately captured by a diffusive mixing-length flux proportional to the angular velocity or angular momentum gradient. Zonal flow averages reveal stable large-scale meridional flow and an entropy deficit near the equator that mirrors the patterns in the angular velocity. The structure of the flow is reminiscent of simulations of stellar surface convection zones and the differential rotation of the Sun, suggesting that similar effects are involved; future simulations will need to address in more detail how the interplay of buoyancy, inertial forces, and turbulent stresses shapes differential rotation during late-stage convection in massive stars. If convective regions develop positive angular velocity gradients, angular momentum could be shuffled out of the core region more efficiently, potentially making the formation of millisecond magnetars more difficult. Our findings have implications for neutron star birth spin periods and supernova explosion scenarios that involve rapid core rotation.
description: 13 pages, 6 figures. Published in MNRAS
Parareal for diffusion problems with space- and time-dependent coefficients
Creators: name: Ruprecht, Daniel
name: Speck, Robert
name: Krause, Rolf
Publisher: name: arXiv
Year: 2014
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics

description: For the time-parallel Parareal method, there exists both numerical and analytical proof that it converges very well for diffusive problems like the heat equation. Many applications, however, do not lead to simple homogeneous diffusive scenarios but feature strongly inhomogeneous and possibly anisotropic coefficients. The paper presents results from a numerical study of how space- and time-dependent coefficients in a diffusion setup affect Parareal's convergence behaviour. It is shown that, for the presented examples, non-constant diffusion coefficients have only marginal influence on how fast Parareal converges. Furthermore, an example is shown that illustrates how for linear problems the maximum singular value of the Parareal iteration matrix can be used to estimate convergence rates.
An efficient jump-diffusion approximation of the Boltzmann equation
Creators: name: Mies, Fabian
name: Sadr, Mohsen
name: Torrilhon, Manuel
Publisher: name: arXiv
Year: 2021
Subjects: subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: A jump-diffusion process along with a particle scheme is devised as an accurate and efficient particle solution to the Boltzmann equation. The proposed process (hereafter Gamma-Boltzmann model) is devised to match the evolution of all moments up to the heat fluxes while attaining the correct Prandtl number of 2/3 for monatomic gas with Maxwellian molecular potential. This approximation model is not subject to issues associated with the previously developed Fokker-Planck (FP) based models; such as having wrong Prandtl number, limited applicability, or requiring estimation of higher-order moments. An efficient particle solution to the proposed Gamma-Boltzmann model is devised and compared computationally to the direct simulation Monte Carlo and the cubic FP model [M. H. Gorji, M. Torrilhon, and P. Jenny, J. Fluid Mech. 680 (2011): 574-601] in several test cases including Couette flow and lid-driven cavity. The simulation results indicate that the Gamma-Boltzmann model yields a good approximation of the Boltzmann equation, provides a more accurate solution compared to the cubic FP in the limit of a low number of particles, and remains computationally feasible even in dense regimes.
Die entscheidenden Aussagen der lutherischen Bekenntnisschriften in ihrer Bedeutung für das 16. und 20. Jahrhundert
Creators: name: Lohse, Bernhard
Publisher: name: Lutherische Kirche in der Welt
Year: 1970

description: Lutherische Kirche in der Welt, Bd. 14 (1967): Jahrbuch des Martin-Luther-Bundes, Band 14