cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
title: Heritage Conservation and Tourism Development in Vernacular Settlements: The Case of Dana Village in Jordan
Creators: name: Allouzi, Rawan
Publisher: name: University of Kent
Year: 2023

description: The recent development of tourism in Jordan is considered a catalyst for the regeneration of the country’s vernacular settlements. Long abandoned, many of these settlements are in poor condition, and their reinvention as tourist venues has recently been considered a way of saving their architectural heritage (Haddad and Fakhoury, 2016). One of the best examples of this phenomenon is Dana village, undergoing dramatic and rapid changes. The rehabilitation project launched by the Royal Society for the Conservation of Nature (RSCN) provided new tourist accommodations within the settlement. The existing dwellings were repaired and transformed while the demolished buildings were rebuilt. The impact of this transformation on the settlement’s heritage has not yet been assessed. This lack of information is not only typical of Dana. There is a general lack of information about assessing the transformation of vernacular settlements into tourist accommodation. This thesis aims to fill this lacuna. Investigating Dana’s transformation, the thesis aims to develop a methodology for assessing the regeneration of abandoned vernacular settlements. This methodology uses Dana as a case study, and starts from a comparative investigation of the original and rebuilt dwellings to understand the architectural, urban, and thermal impact of the adopted restoration approaches. Currently, the original and rebuilt buildings stand side by side, offering a unique opportunity to compare their physical conditions and thermal performance. Combining architectural and urban assessment with thermal assessment is not common in the bibliography, but it is deemed essential to provide an integrated framework for assessing development projects in vernacular settlements, especially in the era of climate change. Field surveys, thermal monitoring, and post occupancy evaluation (POE) interviews were used to collect data, and this is the first attempt to combine these methods in the field of heritage conservation, offering an interdisciplinary study. The study has demonstrated an integrated assessment framework for assessing the transformation of vernacular settlements into tourist accommodations, including the architectural, urban, and thermal aspects. The framework will help local authorities and stakeholders assess the impacts of different transformations, identify challenges, and establish recommendations for professionals in the field of construction who are considering tourism development as a solution for regenerating abandoned villages.
Reweighting Clicks with Dwell Time in Recommendation
Creators: name: Xie, Ruobing
name: Ma, Lin
name: Zhang, Shaoliang
name: Xia, Feng
name: Lin, Leyu
Publisher: name: arXiv
Year: 2022
Subjects: subject: Information Retrieval (cs.IR)
subject: FOS: Computer and information sciences

description: The click behavior is the most widely-used user positive feedback in recommendation. However, simply considering each click equally in training may suffer from clickbaits and title-content mismatching, and thus fail to precisely capture users' real satisfaction on items. Dwell time could be viewed as a high-quality quantitative indicator of user preferences on each click, while existing recommendation models do not fully explore the modeling of dwell time. In this work, we focus on reweighting clicks with dwell time in recommendation. Precisely, we first define a new behavior named valid read, which helps to select high-quality click instances for different users and items via dwell time. Next, we propose a normalized dwell time function to reweight click signals in training for recommendation. The Click reweighting model achieves significant improvements on both offline and online evaluations in real-world systems.
description: 5 pages, accepted by WWW-2023 Companion
Concepts and Criteria for Blind Quantum Source Separation
Creators: name: Deville, Alain
name: Deville, Yannick
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Blind Source Separation (BSS) is an active domain of Classical Information Processing. The development of Quantum Information Processing has made possible the appearance of Blind Quantum Source Separation (BQSS). This article discusses some consequences of the existence of the entanglement phenomenon, and of the probabilistic aspect of quantum measurements, upon BQSS solutions. It focuses on a pair of spins initially separately prepared in a pure state, and then with an undesired coupling between these spins. An unentanglement criterion is established for the state of an arbitrary qubit pair, expressed first with probability amplitudes and secondly with probabilities. It is stressed that the concept of statistical independence of the sources, widely used in classical BSS, should be used with care in BQSS, and possibly replaced by some disentanglement principle. It is shown that the coefficients of the development of any qubit pair pure state, over the states of the standard basis, can be expressed with the probabilities of results in the measurements of well-chosen spin components.
description: 11 pages
Supplementary Information from Quantifying the ‘end of history’ through a Bayesian Markov-chain approach
Creators: name: Klimm, Florian
Publisher: name: The Royal Society
Year: 2022
Subjects: subject: 10299 Applied Mathematics not elsewhere classified
subject: FOS: Mathematics
subject: 80201 Analysis of Algorithms and Complexity
subject: FOS: Computer and information sciences

description: Political regimes have been changing throughout human history. After the apparent triumph of liberal democracies at the end of the twentieth century, Francis Fukuyama and others have been arguing that humankind is approaching an ‘end of history’ (EoH) in the form of a universality of liberal democracies. This view has been challenged by recent developments that seem to indicate the rise of defective democracies across the globe. There has been no attempt to quantify the expected EoH with a statistical approach. In this study, we model the transition between political regimes as a Markov process and—using a Bayesian inference approach—we estimate the transition probabilities between political regimes from time-series data describing the evolution of political regimes from 1800 to 2018. We then compute the steady state for this Markov process which represents a mathematical abstraction of the EoH and predicts that approximately 46% of countries will be full democracies. Furthermore, we find that, under our model, the fraction of autocracies in the world is expected to increase for the next half-century before it declines. Using random-walk theory, we then estimate survival curves of different types of regimes and estimate characteristic lifetimes of democracies and autocracies of 244 years and 69 years, respectively. Quantifying the expected EoH allows us to challenge common beliefs about the nature of political equilibria. Specifically, we find no statistical evidence that the EoH constitutes a fixed, complete omnipresence of democratic regimes.
Neural networks for cosmic ray simulations
Creators: name: Sampathkumar, Pranav
name: Pierog, Tanguy
name: Alves Jr., Antonio Augusto
Publisher: name: Scuola Internazionale Superiore di Studi Avanzati (SISSA)
Year: 2023

description: A neural network based model in order to learn the solution to the 1D cascade equation governing the evolution of Extensive Air Showers (EAS) is presented. The neural network is then used to generate the spectra of secondary particles at every height slice. The ability of the network to learn the function to generate the next iteration in shower development is showcased. Pitfalls in using the network in generating the entire shower is discussed. A sequential network model, which can iteratively generate the entire shower from an initial table is presented. We show that the network learns to generate a single step with approximately 5% error and how the network is accurate in the later parts of the shower and error prone in the early parts of the shower.
Limit theorems of a two-phase quantum walk with one defect
Creators: name: Endo, Shimpei
name: Endo, Takako
name: Konno, Norio
name: Segawa, Etsuo
name: Takei, Masato
Publisher: name: arXiv
Year: 2014
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: We treat a position dependent quantum walk (QW) on the line which we assign two different time-evolution operators to positive and negative parts respectively. We call the model "the two-phase QW" here, which has been expected to be a mathematical model of the topological insulator. We obtain the stationary and time-averaged limit measures related to localization for the two-phase QW with one defect. This is the first result on localization for the two-phase QW. The analytical methods are mainly based on the splitted generating function of the solution for the eigenvalue problem, and the generating function of the weight of the passages of the model. In this paper, we call the methods "the splitted generating function method" and "the generating function method", respectively. The explicit expression of the stationary measure is asymmetric for the origin, and depends on the initial state and the choice of the parameters of the model. On the other hand, the time-averaged limit measure has a starting point symmetry and localization effect heavily depends on the initial state and the parameters of the model. Regardless of the strong effect of the initial state and the parameters, the time-averaged limit measure also suggests that localization can be always observed for our two-phase QW. Furthermore, our results imply that there is an interesting relation between the stationary and time-averaged limit measures when the parameters of the model have specific periodicities, which suggests that there is a possibility that we can analyze localization of the two-phase QW with one defect from the stationary measure.
description: 24 pages, 4 figures
Virtual knot cobordism and bounding the slice genus
Creators: name: Boden, Hans U.
name: Chrisman, Micah
name: Gaudreau, Robin
Publisher: name: arXiv
Year: 2017
Subjects: subject: Geometric Topology (math.GT)
subject: FOS: Mathematics
subject: 57M25, 57M27

description: In this paper, we compute the slice genus for many low-crossing virtual knots. For instance, we show that 1295 out of 92800 virtual knots with 6 or fewer crossings are slice, and that all but 248 of the rest are not slice. Key to these results are computations of Turaev's graded genus, which we show extends to give an invariant of virtual knot concordance. The graded genus is remarkably effective as a slice obstruction, and we develop an algorithm that applies virtual unknotting operations to determine the slice genus of many virtual knots with 6 or fewer crossings.
description: 26 pages, many figures, supplementary dataset available online at https://micah46.wixsite.com/micahknots/slicegenus
Finite-Sample Optimal Estimation and Inference on Average Treatment Effects Under Unconfoundedness
Creators: name: Armstrong, Timothy B.
name: Kolesár, Michal
Publisher: name: arXiv
Year: 2017
Subjects: subject: Applications (stat.AP)
subject: Econometrics (econ.EM)
subject: Methodology (stat.ME)
subject: FOS: Computer and information sciences
subject: FOS: Economics and business

description: We consider estimation and inference on average treatment effects under unconfoundedness conditional on the realizations of the treatment variable and covariates. Given nonparametric smoothness and/or shape restrictions on the conditional mean of the outcome variable, we derive estimators and confidence intervals (CIs) that are optimal in finite samples when the regression errors are normal with known variance. In contrast to conventional CIs, our CIs use a larger critical value that explicitly takes into account the potential bias of the estimator. When the error distribution is unknown, feasible versions of our CIs are valid asymptotically, even when $\sqrt{n}$-inference is not possible due to lack of overlap, or low smoothness of the conditional mean. We also derive the minimum smoothness conditions on the conditional mean that are necessary for $\sqrt{n}$-inference. When the conditional mean is restricted to be Lipschitz with a large enough bound on the Lipschitz constant, the optimal estimator reduces to a matching estimator with the number of matches set to one. We illustrate our methods in an application to the National Supported Work Demonstration.
description: 45 pages, plus supplemental materials (11 pages)
Logarithmic catastrophes and Stokes's phenomenon in waves at horizons
Creators: name: Farrell, L. M.
name: Howls, C. J.
name: O'Dell, D. H. J.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Mathematical Physics (math-ph)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Waves propagating near an event horizon display interesting features including logarithmic phase singularities and caustics. We consider an acoustic horizon in a flowing Bose-Einstein condensate where the elementary excitations obey the Bogoliubov dispersion relation. In the hamiltonian ray theory the solutions undergo a broken pitchfork bifurcation near the horizon and one might therefore expect the associated wave structure to be given by a Pearcey function, this being the universal wave function that dresses catastrophes with two control parameters. However, the wave function is in fact an Airy-type function supplemented by a logarithmic phase term, a novel type of wave catastrophe. Similar wave functions arise in aeroacoustic flows from jet engines and also gravitational horizons if dispersion which violates Lorentz symmetry in the UV is included. The approach we take differs from previous authors in that we analyze the behaviour of the integral representation of the wave function using exponential coordinates. This allows for a different treatment of the branches that gives rise to an analysis based purely on saddlepoint expansions, which resolve the multiple real and complex waves that interact at the horizon and its companion caustic. We find that the horizon is a physical manifestation of a Stokes surface, marking the place where a wave is born, and that the horizon and the caustic do not in general coincide: the finite spatial region between them delineates a broadened horizon.
description: 34 pages, 12 figures
How does monetary policy affect income inequality in Japan? Evidence from grouped data
Creators: name: Feldkircher, Martin
name: Kakamu, Kazuhiko
Publisher: name: arXiv
Year: 2018
Subjects: subject: Econometrics (econ.EM)
subject: FOS: Economics and business

description: We examine the effects of monetary policy on income inequality in Japan using a novel econometric approach that jointly estimates the Gini coefficient based on micro-level grouped data of households and the dynamics of macroeconomic quantities. Our results indicate different effects on income inequality for different types of households: A monetary tightening increases inequality when income data is based on households whose head is employed (workers' households), while the effect reverses over the medium term when considering a broader definition of households. Differences in the relative strength of the transmission channels can account for this finding. Finally we demonstrate that the proposed joint estimation strategy leads to more informative inference while results based on the frequently used two-step estimation approach yields inconclusive results.
description: 25 pages
Floquet transmission in Weyl/multi-Weyl and nodal-line semimetals through a time-periodic potential well
Creators: name: Bera, Sandip
name: Sekh, Sajid
name: Mandal, Ipsita
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: In mesoscopic physics, the application of a time-periodic drive leads to novel transport behaviour, which is absent in the static regimes. Here we consider a quantum pumping protocol, such that the quasiparticles of Weyl/multi-Weyl and nodal-line semimetals are subjected to a time-periodic rectangular potential well. The presence of an oscillating potential of frequency $ω$ creates equispaced Floquet side-bands with spacing $\hbar ω$. As a result, a Fano resonance is observed when the difference in the Fermi energy (i.e., the energy of the incident quasiparticle), and the energy of one of the (quasi)bound state levels of the well, coincides with the energy of an integer number of photons (each carrying energy quantum $\hbar ω$, equal to the side-band spacing). Using the Floquet theory and the scattering matrix approach, in the zero-temperature non-adiabatic pumping limit, we find characteristic Fano resonance patterns in the transmission coefficients, which depend on the nature of the dispersion. The inflection points in the pumped shot noise spectra also serve as a proxy for the corresponding Fano resonances. Therefore, we also numerically evaluate the pumped shot noise. Finally, we correlate the existence of the Fano resonance points to the (quasi)bound states of the well, by explicitly calculating the bound states of the static well (which are a subset of the bound states of the driven system). Since we consider semimetals with anisotropic dispersions, all the features observed depend on the orientation of the potential well. We believe that our results will serve as a guide for future experiments investigating quantum transmission in nonequilibrium settings.
description: journal version
Modeling and mapping the burden of disease in Kenya
Creators: name: Frings, Michael
name: Lakes, Tobia
name: Müller, Daniel
name: Khan, M. M. H.
name: Epprecht, Michael
name: Kipruto, Samuel
name: Galea-Soler, Sandro
name: Gruebner, Oliver
Publisher: name: Humboldt-Universität zu Berlin
Year: 2018
Subjects: subject: 610 Medizin und Gesundheit

description: Precision public health approaches are crucial for targeting health policies to regions most affected by disease. We present the first sub-national and spatially explicit burden of disease study in Africa. We used a cross-sectional study design and assessed data from the Kenya population and housing census of 2009 for calculating YLLs (years of life lost) due to premature mortality at the division level (N = 612). We conducted spatial autocorrelation analysis to identify spatial clusters of YLLs and applied boosted regression trees to find statistical associations between locational risk factors and YLLs. We found statistically significant spatial clusters of high numbers of YLLs at the division level in western, northwestern, and northeastern areas of Kenya. Ethnicity and household crowding were the most important and significant risk factors for YLL. Further positive and significantly associated variables were malaria endemicity, northern geographic location, and higher YLL in neighboring divisions. In contrast, higher rates of married people and more precipitation in a division were significantly associated with less YLL. We provide an evidence base and a transferable approach that can guide health policy and intervention in sub-national regions afflicted by disease burden in Kenya and other areas of comparable settings.
Fires on large recursive trees
Creators: name: Marzouk, Cyril
Publisher: name: arXiv
Year: 2014
Subjects: subject: Probability (math.PR)
subject: FOS: Mathematics

description: We consider random dynamics on a uniform random recursive tree with $n$ vertices. Successively, in a uniform random order, each edge is either set on fire with some probability $p_n$ or fireproof with probability $1-p_n$. Fires propagate in the tree and are only stopped by fireproof edges. We first consider the proportion of burnt and fireproof vertices as $n\to\infty$, and prove a phase transition when $p_n$ is of order $\ln n/n$. We then study the connectivity of the fireproof forest, more precisely the existence of a giant component. We finally investigate the sizes of the burnt subtrees.
description: Accepted for publication in Stochastic Processes and their Applications. 24 pages, 4 figures
Prospects for LISA to detect a gravitational-wave background from first order phase transitions
Creators: name: Boileau, Guillaume
name: Christensen, Nelson
name: Gowling, Chloe
name: Hindmarsh, Mark
name: Meyer, Renate
Publisher: name: arXiv
Year: 2022
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: First order phase transitions in the early universe could produce a gravitational-wave background that might be detectable by the Laser Interferometer Space Antenna (LISA). Such an observation would provide evidence for physics beyond the Standard Model. We study the ability of LISA to observe a gravitational-wave background from phase transitions in the presence of an extragalactic foreground from binary black hole mergers throughout the universe, a galactic foreground from white dwarf binaries, and LISA noise. Modelling the phase transition gravitational wave background as a double broken power law, we use the deviance information criterion as a detection statistic, and Fisher matrix and Markov Chain Monte Carlo methods to assess the measurement accuracy of the parameters of the power spectrum. While estimating all the parameters associated with the gravitational-wave backgrounds, foregrounds, and LISA noise, we find that LISA could detect a gravitational-wave background from phase transitions with a peak frequency of 1 mHz and normalized energy density amplitude of $Ω_{\text p} \simeq 3 \times 10^{-11}$. With $Ω_{\text p} \simeq 10^{-10}$, the signal is detectable if the peak frequency is in the range $4 \times 10^{-4}$ to $9 \times 10^{-3}$ Hz, and the peak amplitude and frequency can be estimated to an accuracy of 10\% to 1\%.
Effects of Hypocaloric Low-Fat, Ketogenic and Ketogenic & Ketone Supplement diets on Aldosterone and Renin
Creators: name: Belany, Paul
name: Kackley, Madison L.
name: Zhao, Songzhu
name: Kluwe, Bjorn
name: Buga, Alex
name: Crabtree, Christopher D.
name: Nedungadi, Divya
name: Kline, David M.
name: N Brock, Guy
name: P. Simonetti, Orlando
name: S. Volek, Jeff
name: Joseph, Joshua
Publisher: name: figshare
Year: 2022
Subjects: Medicine

description: Supplemental Material - Effects of Hypocaloric Low-Fat, Ketogenic and Ketogenic & Ketone Supplement diets on Aldosterone and Renin
Property (T) discrete quantum groups and subfactors with triangle presentations
Creators: name: Vaes, Stefaan
name: Valvekens, Matthias
Publisher: name: arXiv
Year: 2018
Subjects: subject: Operator Algebras (math.OA)
subject: Group Theory (math.GR)
subject: Quantum Algebra (math.QA)
subject: FOS: Mathematics

description: Kazhdan's property (T) has been studied for several discrete group-like structures, including standard invariants of Jones' subfactors and discrete quantum groups. We prove a Zuk-type spectral gap criterion for property (T) in this setting. This allows us to construct a family of property (T) discrete quantum groups, as well as subfactor standard invariants, given by generators and a triangle presentation. These are the first examples of property (T) discrete quantum groups that are not directly related to a discrete group with property (T).
description: v2: Minor changes, final version, to appear in Advances in Mathematics
Context-Aware Resource Allocation in Cellular Networks
Creators: name: Abdelhadi, Ahmed
name: Clancy, Charles
Publisher: name: arXiv
Year: 2014
Subjects: subject: Networking and Internet Architecture (cs.NI)
subject: FOS: Computer and information sciences

description: We define and propose a resource allocation architecture for cellular networks. The architecture combines content-aware, time-aware and location-aware resource allocation for next generation broadband wireless systems. The architecture ensures content-aware resource allocation by prioritizing real-time applications users over delay-tolerant applications users when allocating resources. It enables time-aware resource allocation via traffic-dependent pricing that varies during different hours of day (e.g. peak and off-peak traffic hours). Additionally, location-aware resource allocation is integrable in this architecture by including carrier aggregation of various frequency bands. The context-aware resource allocation is an optimal and flexible architecture that can be easily implemented in practical cellular networks. We highlight the advantages of the proposed network architecture with a discussion on the future research directions for context-aware resource allocation architecture. We also provide experimental results to illustrate a general proof of concept for this new architecture.
description: (c) 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works
Correlation Clustering Based Coalition Formation For Multi-Robot Task Allocation
Creators: name: Dutta, Ayan
name: Ufimtsev, Vladimir
name: Asaithambi, Asai
Publisher: name: arXiv
Year: 2018
Subjects: subject: Multiagent Systems (cs.MA)
subject: Robotics (cs.RO)
subject: FOS: Computer and information sciences

description: In this paper, we study the multi-robot task allocation problem where a group of robots needs to be allocated to a set of tasks so that the tasks can be finished optimally. One task may need more than one robot to finish it. Therefore the robots need to form coalitions to complete these tasks. Multi-robot coalition formation for task allocation is a well-known NP-hard problem. To solve this problem, we use a linear-programming based graph partitioning approach along with a region growing strategy which allocates (near) optimal robot coalitions to tasks in a negligible amount of time. Our proposed algorithm is fast (only taking 230 secs. for 100 robots and 10 tasks) and it also finds a near-optimal solution (up to 97.66% of the optimal). We have empirically demonstrated that the proposed approach in this paper always finds a solution which is closer (up to 9.1 times) to the optimal solution than a theoretical worst-case bound proved in an earlier work.
Deep learning for gradient flows using the Brezis-Ekeland principle
Creators: name: Carini, Laura
name: Jensen, Max
name: Nürnberg, Robert
Publisher: name: arXiv
Year: 2022
Subjects: subject: Numerical Analysis (math.NA)
subject: Machine Learning (cs.LG)
subject: FOS: Mathematics
subject: FOS: Computer and information sciences
subject: 35K15, 35A15, 68T07

description: We propose a deep learning method for the numerical solution of partial differential equations that arise as gradient flows. The method relies on the Brezis--Ekeland principle, which naturally defines an objective function to be minimized, and so is ideally suited for a machine learning approach using deep neural networks. We describe our approach in a general framework and illustrate the method with the help of an example implementation for the heat equation in space dimensions two to seven.
description: Proceeding of the Equadiff 15 conference (https://conference.math.muni.cz/equadiff15)
Classification of regular subalgebras of the hyperfinite II_1 factor
Creators: name: Popa, Sorin
name: Shlyakhtenko, Dimitri
name: Vaes, Stefaan
Publisher: name: arXiv
Year: 2018
Subjects: subject: Operator Algebras (math.OA)
subject: Dynamical Systems (math.DS)
subject: FOS: Mathematics

description: We prove that the regular von Neumann subalgebras $B$ of the hyperfinite II_1 factor $R$ satisfying the condition $B'\cap R=Z(B)$ are completely classified (up to conjugacy by an automorphism of $R$) by the associated discrete measured groupoid $G$. We obtain a similar classification result for triple inclusions $A\subset B \subset R$, where $A$ is a Cartan subalgebra in $R$ and the intermediate von Neumann algebra $B$ is regular in $R$. A key step in proving these results is to show the vanishing cohomology for the associated cocycle actions of $G$ on $B$. We in fact prove two very general vanishing cohomology results for free cocycle actions of amenable discrete measured groupoids on arbitrary tracial von Neumann algebras $B$, resp. Cartan inclusions $A\subset B$. Our work provides a unified approach and generalizations to many known vanishing cohomology and classification results [CFW81], [O85], [ST84], [BG84], [FSZ88], [P18], etc.
description: v2: final version, minor changes, to appear in Journal de Math\'ematiques Pures et Appliqu\'ees
Phase diagram of twisted bilayer graphene at filling factor $ν=\pm3$
Creators: name: Xie, Fang
name: Kang, Jian
name: Bernevig, B. Andrei
name: Vafek, Oskar
name: Regnault, Nicolas
Publisher: name: arXiv
Year: 2022
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We study the correlated insulating phases of twisted bilayer graphene (TBG) in the absence of lattice strain at integer filling $ν=\pm3$. Using the self-consistent Hartree-Fock method on a particle-hole symmetric model and allowing translation symmetry breaking terms, we obtain the phase diagram with respect to the ratio of $AA$ interlayer hopping $(w_0)$ and $AB$ interlayer hopping $(w_1)$. When the interlayer hopping ratio is close to the chiral limit ($w_0/w_1 \lesssim 0.5$), a quantum anomalous Hall state with Chern number $ν_c = \pm 1$ can be observed consistent with previous studies. Around the realistic value $w_0/w_1 \approx 0.8$, we find a spin and valley polarized, translation symmetry breaking, state with $C_{2z}T$ symmetry, a charge gap and a doubling of the moiré unit cell, dubbed the $C_{2z}T$ stripe phase. The real space total charge distribution of this $C_{2z}T$ stripe phase in the flat band limit does not have modulation between different moiré unit cells, although the charge density in each layer is modulated, and the translation symmetry is strongly broken. Other symmetries, including $C_{2z}$, $C_{2x}$ and particle-hole symmetry $P$, and the topology of the $C_{2z}T$ stripe phase are also discussed in detail. We observed braiding and annihilation of the Dirac nodes by continuously turning on the order parameter to its fully self-consistent value, and provide a detailed explanation of the mechanism for the charge gap opening despite preserving $C_{2z}T$ and valley $U(1)$ symmetries. In the transition region between the quantum anomalous Hall phase and the $C_{2z}T$ stripe phase, we find an additional competing state with comparable energy corresponding to a phase with a tripling of the moiré unit cell.
description: 39 pages, 33 figures
Multiple choices of time in quantum cosmology
Creators: name: Malkiewicz, Przemyslaw
Publisher: name: arXiv
Year: 2014
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: It is often conjectured that a choice of time function merely sets up a frame for the quantum evolution of gravitational field, meaning that all choices should be in some sense compatible. In order to explore this conjecture (and the meaning of compatibility), we develop suitable tools for determining the relation between quantum theories based on different time functions. First, we discuss how a time function fixes a canonical structure on the constraint surface. The presentation includes both the kinematical and the reduced perspective, and the relation between them. Second, we formulate twin theorems about the existence of two inequivalent maps between any two deparameterizations, a {\it formal canonical} and a {\it coordinate} one. They are used to separate the effect of choice of clock from other effects. We show, in an example, how the spectra of quantum observables are transformed under the change of clock and prove, via a general argument, the existence of choice-of-time-induced semiclassical effects. Finally, we study an example, in which we find that the semiclassical discrepancies can in fact be arbitrarily large for dynamical observables. We conclude that the values of critical energy density or critical volume in the bouncing scenarios of quantum cosmology cannot in general be at the Planck scale and always need to be given with reference to a specific time function.
description: 22 pages, 7 figures
Prime Structures in a Morita Context
Creators: name: Calci, Mete Burak
name: Halicioglu, Sait
name: Harmanci, Abdullah
name: Ungor, Burcu
Publisher: name: arXiv
Year: 2018
Subjects: subject: Rings and Algebras (math.RA)
subject: FOS: Mathematics
subject: 16D80, 16S50, 16S99

description: In this paper, we study on the primeness and semiprimeness of a Morita context related to the rings and modules. Necessary and sufficient conditions are investigated for an ideal of a Morita context to be a prime ideal and a semiprime ideal. In particular, we determine the conditions under which a Morita context is prime and semiprime.
Group Field Theory and Holographic Tensor Networks: Dynamical Corrections to the Ryu-Takayanagi formula
Creators: name: Chirco, Goffredo
name: Goeßmann, Alex
name: Oriti, Daniele
name: Zhang, Mingyi
Publisher: name: arXiv
Year: 2019
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: We introduce group field theory networks as a generalization of spin networks and of (symmetric) random tensor networks and provide a statistical computation of the Rényi entropy for a bipartite network state using the partition function of a simple interacting group field theory. The expectation value of the entanglement entropy is calculated by an expansion into stranded Feynman graphs and is shown to be captured by a Ryu- Takayanagi formula. For a simple interacting group field theory, we can prove the linear corrections, given by a polynomial perturbation of the Gaussian measure, to be negligible for a broad class of networks.
description: 40 pages, 13 figures
Cosmic ray propagation and dark matter in light of the latest AMS-02 data
Creators: name: Jin, Hong-Bo
name: Wu, Yue-Liang
name: Zhou, Yu-Feng
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: The AMS-02 experiment is measuring the high energy charged cosmic rays with unprecedented accuracy. We explore the possibility of determining the cosmic-ray propagation models using the AMS-02 data $alone$. A global Bayesian analysis of the constraints on the cosmic-ray propagation models from the latest AMS-02 data on the Boron to Carbon nuclei flux ratio and proton flux is performed, with the assumption that the primary nucleon source is a broken power law in rigidity. The ratio of the diffusion coefficient $D_{0}$ to the diffusive halo height $Z_{h}$ is found to be determined with high accuracy $D_{0}/Z_{h}\simeq 2.00\pm0.07\text{cm}^{2}\text{s}^{-1}\text{kpc}^{-1}$. The best-fit value of the halo width is $Z_{h}\simeq 3.3$ kpc with uncertainty less than $50\$. As a consequence, the typical uncertainties in the positron fraction is within a factor of two, and that in the antiproton flux is within an order of magnitude. Both of them are significantly smaller than that from the analyses prior to AMS-02. Taking into account all the uncertainties and correlations in the propagation parameters we derive conservative upper limits on the cross sections for DM annihilating into various standard model final states from the current PAMELA antiproton data. We also investigate the reconstruction capability of the future AMS-02 antiproton data on the DM properties. The result shows that for DM particles lighter than 100 GeV and with typical thermal annihilation cross section, the cross section can be well reconstructed with uncertainties about a factor of two for the AMS-02 three-year data taking.
description: 39 pages, 9 figures. Detailed discussions on the validity of using proton flux and B/C ratio to determine all the propagation parameters added. Version to appear in JCAP
A novel approach to robust radar detection of range-spread targets
Creators: name: Coluccia, Angelo
name: Fascista, Alessio
name: Ricci, Giuseppe
Publisher: name: arXiv
Year: 2019
Subjects: subject: Signal Processing (eess.SP)
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: This paper proposes a novel approach to robust radar detection of range-spread targets embedded in Gaussian noise with unknown covariance matrix. The idea is to model the useful target echo in each range cell as the sum of a coherent signal plus a random component that makes the signal-plus-noise hypothesis more plausible in presence of mismatches. Moreover, an unknown power of the random components, to be estimated from the observables, is inserted to optimize the performance when the mismatch is absent. The generalized likelihood ratio test (GLRT) for the problem at hand is considered. In addition, a new parametric detector that encompasses the GLRT as a special case is also introduced and assessed. The performance assessment shows the effectiveness of the idea also in comparison to natural competitors.
description: 28 pages, 8 figures
Specification for expressing resource capabilities (AARC-G027)
Creators: name: AARC Consortium Partners
name: AppInt Members
Publisher: name: Zenodo
Year: 2018
Subjects: capability-based access control
authorisation
identity
infrastructures
AARC

description: This document provides a specification for expressing resource-specific capabilities using entitlements. A capability defines the resource or child-resource a user is allowed to access, optionally specifying certain actions the user is entitled to perform. Capabilities can be used to convey - in a compact form - authorisation information.
On the square-free representation function of a norm form and nilsequences
Creators: name: Matthiesen, Lilian
Publisher: name: arXiv
Year: 2014
Subjects: subject: Number Theory (math.NT)
subject: FOS: Mathematics

description: We show that the restriction to square-free numbers of the representation function attached to a norm form does not correlate with nilsequences. By combining this result with previous work of Browning and the author, we obtain an application that is used in recent work of Harpaz and Wittenberg on the fibration method for rational points.
description: 26 pages; revision taking into account referee's comments
A Review on Deep Learning in Medical Image Reconstruction
Creators: name: Zhang, Haimiao
name: Dong, Bin
Publisher: name: arXiv
Year: 2019
Subjects: subject: Image and Video Processing (eess.IV)
subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Machine Learning (cs.LG)
subject: Medical Physics (physics.med-ph)
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Computer and information sciences
subject: FOS: Physical sciences
subject: 60H10, 92C55, 93C15, 94A08

description: Medical imaging is crucial in modern clinics to guide the diagnosis and treatment of diseases. Medical image reconstruction is one of the most fundamental and important components of medical imaging, whose major objective is to acquire high-quality medical images for clinical usage at minimal cost and risk to the patients. Mathematical models in medical image reconstruction or, more generally, image restoration in computer vision, have been playing a prominent role. Earlier mathematical models are mostly designed by human knowledge or hypothesis on the image to be reconstructed, and we shall call these models handcrafted models. Later, handcrafted plus data-driven modeling started to emerge which still mostly relies on human designs, while part of the model is learned from the observed data. More recently, as more data and computation resources are made available, deep learning based models (or deep models) pushed data-driven modeling to the extreme where the models are mostly based on learning with minimal human designs. Both handcrafted and data-driven modeling have their own advantages and disadvantages. One of the major research trends in medical imaging is to combine handcrafted modeling with deep modeling so that we can enjoy benefits from both approaches. The major part of this article is to provide a conceptual review of some recent works on deep modeling from the unrolling dynamics viewpoint. This viewpoint stimulates new designs of neural network architectures with inspiration from optimization algorithms and numerical differential equations. Given the popularity of deep modeling, there are still vast remaining challenges in the field, as well as opportunities which we shall discuss at the end of this article.
description: 31 pages, 6 figures. Survey paper. Revise the typos
Boosting thermodynamic performance by bending space-time
Creators: name: Ferketic, Emily E.
name: Deffner, Sebastian
Publisher: name: arXiv
Year: 2022
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Black holes are arguably the most extreme regions of the universe. Yet, they are also utterly inaccessible to experimentation, and even just indirect observation poses significant technical challenges. The phenomenological approach of thermodynamics is uniquely suited to explore at least some of the physical properties of such scenarios, and this has motivated the study of so-called holographic engines. We show that the efficiency of an endoreversible Brayton cycle is given by the Curzon-Ahlborn efficiency if the engine is fueled by a 2-dimensional ideal gas; and that the efficiency is higher, if the working medium is a (2+1)-dimensional BTZ black hole. These findings may be relevant not only in the quest to unlock the mysteries of black holes, but also for potential technological applications of graphene.
description: 6 pages, 5 figures
A Constant-Factor Approximation Algorithm for Online Coverage Path Planning with Energy Constraint
Creators: name: Dutta, Ayan
name: Sharma, Gokarna
Publisher: name: arXiv
Year: 2019
Subjects: subject: Robotics (cs.RO)
subject: Data Structures and Algorithms (cs.DS)
subject: FOS: Computer and information sciences

description: In this paper, we study the problem of coverage planning by a mobile robot with a limited energy budget. The objective of the robot is to cover every point in the environment while minimizing the traveled path length. The environment is initially unknown to the robot. Therefore, it needs to avoid the obstacles in the environment on-the-fly during the exploration. As the robot has a specific energy budget, it might not be able to cover the complete environment in one traversal. Instead, it will need to visit a static charging station periodically in order to recharge its energy. To solve the stated problem, we propose a budgeted depth-first search (DFS)-based exploration strategy that helps the robot to cover any unknown planar environment while bounding the maximum path length to a constant-factor of the shortest-possible path length. Our $O(1)$-approximation guarantee advances the state-of-the-art of log-approximation for this problem. Simulation results show that our proposed algorithm outperforms the current state-of-the-art algorithm both in terms of the traveled path length and run time in all the tested environments with concave and convex obstacles.
Knight shift and nuclear spin relaxation in Fe/n-GaAs heterostructures
Creators: name: Christie, Kevin D.
name: Geppert, Chad C.
name: Patel, Sahil J.
name: Hu, Q. O.
name: Palmstrøm, Chris J.
name: Crowell, Paul A.
Publisher: name: arXiv
Year: 2014
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We investigate the dynamically polarized nuclear-spin system in Fe/\emph{n}-GaAs heterostructures using the response of the electron-spin system to nuclear magnetic resonance (NMR) in lateral spin-valve devices. The hyperfine interaction is known to act more strongly on donor-bound electron states than on those in the conduction band. We provide a quantitative model of the temperature dependence of the occupation of donor sites. With this model we calculate the ratios of the hyperfine and quadrupolar nuclear relaxation rates of each isotope. For all temperatures measured, quadrupolar relaxation limits the spatial extent of nuclear spin-polarization to within a Bohr radius of the donor sites and is directly responsible for the isotope dependence of the measured NMR signal amplitude. The hyperfine interaction is also responsible for the $2\text{ kHz}$ Knight shift of the nuclear resonance frequency that is measured as a function of the electron spin accumulation. The Knight shift is shown to provide a measurement of the electron spin-polarization that agrees qualitatively with standard spin transport measurements.
description: 7 figures - accepted for publication in Phys. Rev. B
Topological invariants based on generalized position operators and application to the interacting Rice-Mele model
Creators: name: Aligia, Armando A.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We discuss different properties and the ability of several topological invariants based on position operators to identify phase transitions, and compare with more accurate methods, like crossing of excited energy levels and jumps in Berry phases. The invariants have the form $\text{Im} \text{ln} \left\langle \exp \left[ i(2π/L)Σ_{j}x_{j} \left( m_{_{\uparrow }}\hat{n}_{j\uparrow } +m_{\downarrow }\hat{n}_{j\downarrow }\right) \right] \right\rangle $, where $L$ is the length of the system, $x_{j}$ the position of the site $j$, $\hat{n}_{jσ}$ the operator of the number of particles at site $j$ with spin $σ$. We show that $m_{σ}$ should be integers, and in some cases of magnitude larger than 1 to lead to well defined expectation values. For the interacting Rice-Mele model (which contains the interacting Su-Schrieffer-Heeger and the Ionic Hubbard model as specific cases), we show that three different invariants give complementary information and are necessary and sufficient to construct the phase diagrams in the regions where the invariants are protected by inversion symmetry. We also discuss the consequences for pumping of charge and spin, and the effect of an Ising spin-spin interaction or a staggered magnetic field.
description: 12 pages, 7 figures, some references added, printing errors corrected