cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Deep Boltzmann machines: rigorous results at arbitrary depth
Creators: name: Alberici, Diego
name: Contucci, Pierluigi
name: Mingione, Emanuele
Publisher: name: arXiv
Year: 2020
Subjects: subject: Mathematical Physics (math-ph)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: A class of deep Boltzmann machines is considered in the simplified framework of a quenched system with Gaussian noise and independent entries. The quenched pressure of a $K$-layers spin glass model is studied allowing interactions only among consecutive layers. A lower bound for the pressure is found in terms of a convex combination of $K$ Sherrington-Kirkpatrick models and used to study the annealed and replica symmetric regimes of the system. A map with a one dimensional monomer-dimer system is identified and used to rigorously control the annealed region at arbitrary depth $K$ with the methods introduced by Heilmann and Lieb. The compression of this high noise region displays a remarkable phenomenon of localisation of the processing layers. Furthermore a replica symmetric lower bound for the limiting quenched pressure of the model is obtained in a suitable region of the parameters and the replica symmetric pressure is proved to have a unique stationary point.
description: 28 pages
Decoherence assisting a measurement-driven quantum evolution process
Creators: name: Roa, L.
name: Olivares, G.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We study the problem of driving an unknown initial mixed quantum state onto a known pure state without using unitary transformations. This can be achieved, in an efficient manner, with the help of sequential measurements on at least two unbiased bases. However here we found that, when the system is affected by a decoherence mechanism, only one observable is required in order to achieve the same goal. In this way the decoherence can assist the process. We show that, depending on the sort of decoherence, the process can converge faster or slower than the method implemented by means of two complementary observables.
description: Four pages, three figures included (lroa@udec.cl)
Efficient and Secure Flash-based Gaming CAPTCH
Creators: name: Aldwairi, Monther
name: Mohammed, Suaad
name: Padmanabhan, Megana Lakshmi
Publisher: name: arXiv
Year: 2020
Subjects: subject: Cryptography and Security (cs.CR)
subject: FOS: Computer and information sciences

description: With the growth of connectivity to smart grids, new applications, and the changing interaction between customer and energy clouds, clouds are more vulnerable to denial-of-service attacks. Efficient detection methods are required to authenticate, detect and control attackers. Completely Automated Public Turing test to tell Computers and Humans Apart, CAPTCHA, is one efficient tool to thwart denial of service attacks. The server presents the user with a client puzzle to solve in order to gain access to the service or website. The puzzle should be hard enough for computers, but easy for humans to solve. Several methods have been suggested including the popular image-based, as well as video-based, and text-based CAPTCHAs. In this paper, we present a new Flash-based gaming CAPTCHA to differentiate bots from humans. We propose a drag and drop client puzzle where the user will play a simple game to answer a visual question. Our method turns out to be convenient, easy for users and challenging for bots. Additionally, it has gaming aspect, which makes it interesting to users of all age groups.
Interpolation formula for the reflection coefficient distribution of absorbing chaotic cavities in the presence of time reversal symmetry
Creators: name: Martinez-Mares, M.
name: Mendez-Sanchez, R. A.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We propose an interpolation formula for the distribution of the reflection coefficient in the presence of time reversal symmetry for chaotic cavities with absorption. This is done assuming a similar functional form as that when time reversal invariance is absent. The interpolation formula reduces to the analytical expressions for the strong and weak absorption limits. Our proposal is compared to the quite complicated exact result existing in the literature.
description: 7 pages, 3 figures
The role of consumers’ perceptions in the valuation of food safety and convenience attributes of vegetables in Vietnam
Creators: name: Mergenthaler, Marcus
name: Weinberger, Katinka
name: Qaim, Matin
name: Mergenthaler, Marcus
name: Weinberger, Katinka
name: Qaim, Matin
Publisher: name: Unknown
Year: 2009
Subjects: subject: Agricultural and Food Policy
subject: Consumer/Household Economics
subject: Demand and Price Analysis
subject: Food Consumption/Nutrition/Food Safety
subject: International Development
subject: Marketing
subject: FOS: Economics and business
subject: contingent valuation
subject: convenience
subject: food quality
subject: food safety
subject: mediation framework
subject: transformation of food systems
subject: Vietnam

description: Food systems in developing countries are undergoing a profound transformation characterized by the emergence and expansion of modern retailers and integrated supply chains. Appropriate policies are needed to guide this transformation, presupposing a good understanding of consumer preferences. We analyze consumers’ valuation of different vegetable attributes in metropolitan areas of Vietnam, using contingent valuation techniques and a mediation framework for two specific examples. Consumers are willing to pay an average price premium of 60% for Chinese mustard that is free of chemical residues and of 19% for different convenience attributes of potatoes. Income levels and media have positive impacts on the willingness to pay, partly mediated through different consumer perceptions like food safety concerns, openness towards new food products or price consciousness. These results deepen our understanding on how consumers value new food attributes.
Unraveling the Global Teleconnections of Indian Summer Monsoon Clouds: Expedition from CMIP5 to CMIP6
Creators: name: Dutta, Ushnanshu
name: Hazra, Anupam
name: Chaudhari, Hemantkumar S.
name: Saha, Subodh Kumar
name: Pokhrel, Samir
name: Verma, Utkarsh
Publisher: name: arXiv
Year: 2021
Subjects: subject: Atmospheric and Oceanic Physics (physics.ao-ph)
subject: FOS: Physical sciences

description: We have analyzed the teleconnection of total cloud fraction (TCF) with global sea surface temperature (SST) in multi-model ensembles (MME) of the fifth and sixth Coupled Model Intercomparison Projects (CMIP5 and CMIP6). CMIP6-MME has a more robust and realistic teleconnection (TCF and global SST) pattern over the extra-tropics (R ~0.43) and North Atlantic (R ~0.39) region, which in turn resulted in improvement of rainfall bias over the Asian summer monsoon (ASM) region. CMIP6-MME can better reproduce the mean TCF and have reduced dry (wet) rainfall bias on land (ocean) over the ASM region. CMIP6-MME has improved the biases of seasonal mean rainfall, TCF, and outgoing longwave radiation (OLR) over the Indian Summer Monsoon (ISM) region by ~40%, ~45%, and ~31%, respectively, than CMIP5-MME and demonstrates better spatial correlation with observation/reanalysis. Results establish the credibility of the CMIP6 models and provide a scientific basis for improving the seasonal prediction of ISM.
description: 12 pages, 4 main figures, 2 supplementary figures
Biofuels and Land Use Change
Creators: name: Reilly, John M.
name: Gurgel, Angelo Costa
name: Paltsev, Sergey
name: Reilly, John M.
name: Gurgel, Angelo Costa
name: Paltsev, Sergey
Publisher: name: Unknown
Year: 2008
Subjects: Land Economics/Use

description: Biofuels may make a substantial contribution to meeting the world’s energy needs. That contribution may come sooner and be greater if there is a strong climate policy to reduce greenhouse gases and biofuels can be produced in a way that minimizes greenhouse gas emissions. We investigate the land use implications of biofuels under different policy conditions using a computable general equilibrium model of the world economy that has been adapted to explicitly consider land use change. We find that to meet a substantial portion of the worlds liquid fuel needs a global area approximately equal to that of today’s cropland would be needed. As much as two-thirds of the land could come from intensification of existing land, especially pastureland. Conversion of forests and the loss of natural ecosystems and carbon dioxide emissions associated with land use change present a substantial risk. We also find that comparative advantage in biofuels likely rests in the tropics despite belief in the US that biofuels could be a domestic source of energy, freeing us from imports. An attempt to meet US fuel needs through a domestic biofuels program would likely mean the US would become a major food importer and would contribute to higher land and food prices in the US.
Current-induced magnetization switching of exchange-biased NiO heterostructures characterized by spin-orbit torque
Creators: name: Grochot, Krzysztof
name: Karwacki, Łukasz
name: Łazarski, Stanisław
name: Skowroński, Witold
name: Kanak, Jarosław
name: Powroźnik, Wiesław
name: Kuświk, Piotr
name: Kowacz, Mateusz
name: Stobiecki, Feliks
name: Stobiecki, Tomasz
Publisher: name: arXiv
Year: 2020
Subjects: subject: Applied Physics (physics.app-ph)
subject: FOS: Physical sciences

description: In this work, we study magnetization switching induced by spin-orbit torque in W(Pt)/Co/NiO heterostructures with variable thickness of heavy-metal layers W and Pt, perpendicularly magnetized Co layer and an antiferromagnetic NiO layer. Using current-driven switching, magnetoresistance and anomalous Hall effect measurements, perpendicular and in-plane exchange bias field were determined. Several Hall-bar devices possessing in-plane exchange bias from both systems were selected and analyzed in relation to our analytical switching model of critical current density as a function of Pt and W thickness, resulting in estimation of effective spin Hall angle and perpendicular effective magnetic anisotropy. We demonstrate in both the Pt/Co/NiO and the W/Co/NiO systems the deterministic Co magnetization switching without external magnetic field which was replaced by in-plane exchange bias field. Moreover, we show that due to a higher effective spin Hall angle in W than in Pt-systems the relative difference between the resistance states in the magnetization current switching to difference between the resistance states in magnetic field switching determined by anomalous Hall effect ($ΔR/ΔR_{\text{AHE}}$) is about twice higher in W than Pt, while critical switching current density in W is one order lower than in Pt-devices. The current switching stability and training process is discussed in detail.
Meeting Biofuels Targets: Implications for Land Use, Greenhouse Gas Emissions and Nitrogen Use in Illinois
Creators: name: Khanna, Madhu
name: Onal, Hayri
name: Chen, Xiaoguang
name: Huang, Haixiao
name: Khanna, Madhu
name: Onal, Hayri
name: Chen, Xiaoguang
name: Huang, Haixiao
Publisher: name: Unknown
Year: 2008
Subjects: Environmental Economics and Policy
Land Economics/Use

description: This article develops a dynamic micro-economic land use model to identify the cost-effective allocation of cropland for traditional row crops and perennial grasses and the mix of cellulosic feedstocks needed to meet pre-determined biofuel targets over the 2007-2022 period. Yields of perennial grasses are obtained from a biophysical model and together with county level data on costs of production for Illinois are used to examine the implications of these targets for crop and biofuel costs, greenhouse gas emissions, and nitrogen use. The economic viability of cellulosic feedstocks is found to depend on their yields per acre and the opportunity cost of land. The mix of viable cellulosic feedstocks varies spatially and temporally with corn stover and miscanthus co-existing in the state; corn stover is viable mainly in central and northern Illinois while miscanthus acres are primarily located in southern Illinois. Biofuel targets lead to a significant shift in acreage from soybeans and pasture to corn and a change in crop rotation and tillage practices. The biofuel targets assumed here lead to a reduction in greenhouse gas emissions but an increase in nitrogen use.
Additional file 1 of Design of experiments for fine-mapping quantitative trait loci in livestock populations
Creators: name: Wittenburg, Dörte
name: Bonk, Sarah
name: Doschoris, Michael
name: Reyer, Henry
Publisher: name: figshare
Year: 2020
Subjects: subject: Medicine
subject: Genetics
subject: FOS: Biological sciences
subject: Biotechnology
subject: 69999 Biological Sciences not elsewhere classified
subject: 19999 Mathematical Sciences not elsewhere classified
subject: FOS: Mathematics

description: Additional file 1 PDF file containing additional figures.
Einstein Lie groups, geodesic orbit manifolds and regular Lie subgroups
Creators: name: Souris, Nikolaos Panagiotis
Publisher: name: arXiv
Year: 2021
Subjects: subject: Differential Geometry (math.DG)
subject: FOS: Mathematics
subject: 53C25, 53C30

description: We study the relation between two special classes of Riemannian Lie groups $G$ with a left-invariant metric $g$: The Einstein Lie groups, defined by the condition $\operatorname{Ric}_g=cg$, and the geodesic orbit Lie groups, defined by the property that any geodesic is the integral curve of a Killing vector field. The main results imply that extensive classes of compact simple Einstein Lie groups $(G,g)$ are not geodesic orbit manifolds, thus providing large-scale answers to a relevant question of Y. Nikonorov. Our approach involves studying and characterizing the $G\times K$-invariant geodesic orbit metrics on Lie groups $G$ for a wide class of subgroups $K$ that we call (weakly) regular. By-products of our work are structural and characterization results that are of independent interest for the classification problem of geodesic orbit manifolds.
description: Revised version, to appear in the journal Communications in Contemporary Mathematics
The Impact of Ethanol Policy on Social Welfare and GHG Emissions
Creators: name: Lasco, Christine
name: Khanna, Madhu
name: Lasco, Christine
name: Khanna, Madhu
Publisher: name: Unknown
Year: 2008
Subjects: Environmental Economics and Policy

description: We develop a stylized model of fuel markets in an open economy to analyze the impact of ethanol policy on social welfare and greenhouse gas (GHG) emissions. The policies considered here include the $0.51 per gallon blender’s subsidy for ethanol and the import tariff of $0.54 per gallon on sugarcane ethanol. Our analysis shows that the combined subsidy and tariff policy decreases welfare by about $3.6 billion relative to a non intervention policy. Furthermore, there are no GHG mitigation benefits since GHG emissions show a slight increase (0.08%) when both policies are in place.
Semileptonic B Decays with Nf=2+1 Dynamical Quarks
Creators: name: Shigemitsu, J.
name: Davies, C. T. H.
name: Dougall, A.
name: Foley, K.
name: Gamiz, E.
name: Gray, A.
name: Gulez, E.
name: Lepage, G. P.
name: Wingate, M.
Publisher: name: arXiv
Year: 2004
Subjects: subject: High Energy Physics - Lattice (hep-lat)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Semileptonic, B --> pi l,nu, decays are studied on the MILC dynamical configurations using NRQCD heavy and Asqtad light quarks. We work with light valence quark masses ranging between m_s and m_s/8. Preliminary simple linear chiral extrapolations have been carried out for form factors f_para and f_perp at fixed E_pi. The chirally extrapolated results for the form factors f_+(q^2) and f_0(q^2) are then fit to the Becirevic-Kaidalov (BK) ansatz. Preliminary estimates of the CKM matrix element |V_{ub}| are presented based on the recently published branching fractions for B exclusive semileptonic decays by the CLEO collaboration.
description: 3 pages, 1 figure. Contribution to Lattice'04 (heavy quarks)
A Quantum Router Architecture for High-Fidelity Entanglement Flows in Quantum Networks
Creators: name: Lee, Yuan
name: Bersin, Eric
name: Dahlberg, Axel
name: Wehner, Stephanie
name: Englund, Dirk
Publisher: name: arXiv
Year: 2020
Subjects: subject: Quantum Physics (quant-ph)
subject: Applied Physics (physics.app-ph)
subject: FOS: Physical sciences

description: The past decade has seen tremendous progress in experimentally realizing the building blocks of quantum repeaters. Repeater architectures with multiplexed quantum memories have been proposed to increase entanglement distribution rates, but an open challenge is to maintain entanglement fidelity over long-distance links. Here, we address this with a quantum router architecture comprising many quantum memories connected in a photonic switchboard to broker entanglement flows across quantum networks. We compute the rate and fidelity of entanglement distribution under this architecture using an event-based simulator, finding that the router improves the entanglement fidelity as multiplexing depth increases without a significant drop in the entanglement distribution rate. Specifically, the router permits channel-loss-invariant fidelity, i.e. the same fidelity achievable with lossless links. Furthermore, this scheme automatically prioritizes entanglement flows across the full network without requiring global network information. The proposed architecture uses present-day photonic technology, opening a path to near-term deployable multi-node quantum networks.
description: 10 pages, 6 figures + 6 pages appendix
Virial-potential energy correlation and its relation to the density scaling for quasi-real model systems
Creators: name: Koperwas, K.
name: Grzybowski, A.
name: Paluch, M.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: In this letter, we examine the virial and the potential energy correlation for the quasi-real model system. This correlation constitutes the framework of the theory of the isomorph in the liquid phase diagram commonly examined using simple-liquids. Interestingly, our results show that for the systems characterized by structural anisotropy and flexible bonds, the instantaneous values of total viral and total potential energy are entirely uncorrelated. It is due to the presence of the intramolecular interactions because the contributions to the virial and potential energy resulting from the intermolecular interactions still exhibit strong linear dependence. Interestingly, in contrast to the results reported for simple-liquids, the slope of the mentioned linear dependence is different than the values of the density scaling exponent. However, our findings show that for the quasi-real materials, the slope of dependence between the virial and potential energy (resulting from the intermolecular interactions) strongly depends on the range of intermolecular distances that are taken into account. Consequently, the value of the slope of the discussed relationship, which enables satisfactory density scaling, can be obtained. Furthermore, we show that the above crucial range of intermolecular distances does not depend on the structure of the system as well as on the thermodynamic conditions.
The Ups and Downs of the Hubble Constant
Creators: name: Tammann, G. A.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: A brief history of the determination of the Hubble constant H_0 is given. Early attempts following Lemaitre (1927) gave much too high values due to errors of the magnitude scale, Malmquist bias and calibration problems. By 1962 most authors agreed that 75< H_0 <130. After 1975 a dichotomy arose with values near 100 and others around 55. The former came from apparent-magnitude-limited samples and were affected by Malmquist bias. New distance indicators were introduced; they were sometimes claimed to yield high values of H_0, but the most recent data lead to H_0 in the 60's, yet with remaining difficulties as to the zero-point of the respective distance indicators. SNe Ia with their large range and very small luminosity dispersion (avoiding Malmquist bias) offer a unique opportunity to determine the large-scale value of H_0. Their maximum luminosity can be well calibrated from 10 SNe Ia in local parent galaxies whose Cepheids have been observed with HST. An unforeseen difficulty - affecting all Cepheid distances - is that their P-L relation varies from galaxy to galaxy, presumably in function of metallicity. A proposed solution is summarized here. The conclusion is that H_0 = 63.2 +/- 1.3 (random) +/- 5.3 (systematic) on all scales. The expansion age becomes then (with Omega_m=0.3, Omega_Lambda=0.7) 15.1 Gyr.
description: 30 pages, 12 figures, 2 tables. 79th Annual Scientific Meeting of the Astronomische Gesellschaft 2005, Karl-Schwarzschild-Lecture, to appear in Reviews in Modern Astronomy, 19, 1
Scheme for sub-shot-noise transmission measurement using a time multiplexed single-photon source
Creators: name: Magnoni, Agustina G.
name: Knoll, Laura T.
name: Larotonda, Miguel A.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Quantum Physics (quant-ph)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: A promising result from optical quantum metrology is the ability to achieve sub-shot-noise performance in transmission or absorption measurements. This is due to the significantly lower uncertainty in light intensity of quantum beams with respect to their classical counterparts. In this work, we simulate the outcome of an experiment that uses a multiplexed single-photon source based on pair generation by continuous spontaneous parametric down conversion (SPDC) followed by a time multiplexing set-up with a binary temporal division strategy, considering several types of experimental losses. With such source, the sub-Poissonian statistics of the output signal is the key for achieving sub-shot-noise performance. We compare the numerical results with two paradigmatic limits: the shot-noise limit (achieved using coherent sources) and the quantum limit (obtained with an ideal photon-number Fock state as the input source). We also investigate conditions in which threshold detectors can be used, and the effect of input light fluctuations on the measurement error. Results show that sub-shot-noise performance can be achieved, even without using number-resolving detectors, with improvement factors that range from 1.5 to 2. This technique would allow measurements of optical absorption of a sample with reasonable uncertainty using ultra-low light intensity and minimum disruption of biological or other fragile specimens.
description: 10 pages, 8 figures
Robust Peak Detection for Holter ECGs by Self-Organized Operational Neural Networks
Creators: name: Gabbouj, Moncef
name: Kiranyaz, Serkan
name: Malik, Junaid
name: Zahid, Muhammad Uzair
name: Ince, Turker
name: Chowdhury, Muhammad
name: Khandakar, Amith
name: Tahir, Anas
Publisher: name: arXiv
Year: 2021
Subjects: subject: Signal Processing (eess.SP)
subject: Machine Learning (cs.LG)
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Computer and information sciences

description: Although numerous R-peak detectors have been proposed in the literature, their robustness and performance levels may significantly deteriorate in low-quality and noisy signals acquired from mobile electrocardiogram (ECG) sensors, such as Holter monitors. Recently, this issue has been addressed by deep 1-D convolutional neural networks (CNNs) that have achieved state-of-the-art performance levels in Holter monitors; however, they pose a high complexity level that requires special parallelized hardware setup for real-time processing. On the other hand, their performance deteriorates when a compact network configuration is used instead. This is an expected outcome as recent studies have demonstrated that the learning performance of CNNs is limited due to their strictly homogenous configuration with the sole linear neuron model. In this study, to further boost the peak detection performance along with an elegant computational efficiency, we propose 1-D Self-Organized ONNs (Self-ONNs) with generative neurons. The most crucial advantage of 1-D Self-ONNs over the ONNs is their self-organization capability that voids the need to search for the best operator set per neuron since each generative neuron has the ability to create the optimal operator during training. The experimental results over the China Physiological Signal Challenge-2020 (CPSC) dataset with more than one million ECG beats show that the proposed 1-D Self-ONNs can significantly surpass the state-of-the-art deep CNN with less computational complexity. Results demonstrate that the proposed solution achieves a 99.10% F1-score, 99.79% sensitivity, and 98.42% positive predictivity in the CPSC dataset, which is the best R-peak detection performance ever achieved.
description: arXiv admin note: substantial text overlap with arXiv:2110.02215
Impacts of Land Conversion for Biofuel Cropping on Soil Organic Matter and Greenhouse Gas Emissions
Creators: name: Del Grosso, Stephen J.
name: Ogle, Stephen M.
name: Parton, William J.
name: Adler, Paul R.
name: Del Grosso, Stephen J.
name: Ogle, Stephen M.
name: Parton, William J.
name: Adler, Paul R.
Publisher: name: Unknown
Year: 2008
Subjects: Environmental Economics and Policy
Land Economics/Use

description: To assess the value of biofuels, the environmental costs of their production must be compared with the benefits of displacing fossil fuel. This article focuses on the environmental impacts of biofuel cropping systems and calculates net greenhouse gas (GHG) emissions using life cycle analysis. The impacts of corn and switchgrass cropping for ethanol production were calculated for three states in the US (Iowa, Illinois, and Indiana) assuming three previous land use scenarios: Conservation Reserve Program (CRP) land, pasture land, and land already used for cropping. Although the results were different for the 3 states considered, the impacts of previous land use and cropping system were more important than location. Conversion of CRP lands to corn ethanol production would result in little net GHG savings compared to burning fossil fuel, greatly increase NO3 leaching, and constrain other benefits of CRP land such as wildlife habitat. Conversion of pasture and crop land to corn ethanol cropping show GHG benefits, reductions in leaching for previously cropped systems, and increases in leaching for lands previously in pasture. Converting CRP land to switchgrass cropping would lessen the rate at which these soils store SOC, increase N2O emissions, and have little impact on NO3 leaching. Converting pasture and crop land to switchgrass cropping would increase SOC storage, decrease N2O emissions, and decrease NO3 leaching. We conclude that current land management (cropping system, tillage intensity, and fertilizer application), as well as previous land use, must both be considered to quantify the environmental impacts of biofuel cropping systems.
People's Mood and SARS-Cov-2 Mortality
Creators: name: Besharati, Mohammad Reza
name: Izadi, Mohammad
name: Alireza Talebpour
Publisher: name: Zenodo
Year: 2021
Subjects: Sars-Cov-2, Mood, People, COVID-19, Mortality, Mortality Rate, Mortality Percent

description: Calm People Sample Size (with apparent COVID-19 Infection): 266 COVID-19 Mortality Percent: 6.8 Restless, active, energetic People Sample Size (with apparent COVID-19 Infection): 241 COVID-19 Mortality Percent: 2.9
Sampling diverse near-optimal solutions via algorithmic quantum annealing
Creators: name: Mohseni, Masoud
name: Rams, Marek M.
name: Isakov, Sergei V.
name: Eppens, Daniel
name: Pielawa, Susanne
name: Strumpfer, Johan
name: Boixo, Sergio
name: Neven, Hartmut
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: Sampling a diverse set of high-quality solutions for hard optimization problems is of great practical relevance in many scientific disciplines and applications, such as artificial intelligence and operations research. One of the main open problems is the lack of ergodicity, or mode collapse, for typical stochastic solvers based on Monte Carlo techniques leading to poor generalization or lack of robustness to uncertainties. Currently, there is no universal metric to quantify such performance deficiencies across various solvers. Here, we introduce a new diversity measure for quantifying the number of independent approximate solutions for NP-hard optimization problems. Among others, it allows benchmarking solver performance by a required time-to-diversity (TTD), a generalization of often used time-to-solution (TTS). We illustrate this metric by comparing the sampling power of various quantum annealing strategies. In particular, we show that the inhomogeneous quantum annealing schedules can redistribute and suppress the emergence of topological defects by controlling space-time separated critical fronts, leading to an advantage over standard quantum annealing schedules with respect to both TTS and TTD for finding rare solutions. Using path-integral Monte Carlo simulations for up to 1600 qubits, we demonstrate that nonequilibrium driving of quantum fluctuations, guided by efficient approximate tensor network contractions, can significantly reduce the fraction of hard instances for random frustrated 2D spin-glasses with local fields. Specifically, we observe that by creating a class of algorithmic quantum phase transitions, the diversity of solutions can be enhanced by up to 40% with the fraction of hard-to-sample instances reducing by more than 25%.
description: 13 pages, 6 figures, close to published version
Regulation of GHG emissions from biofuel blended energy
Creators: name: Hochman, Gal
name: Rajagopal, Deepak
name: Zilberman, David
name: Hochman, Gal
name: Rajagopal, Deepak
name: Zilberman, David
Publisher: name: Unknown
Year: 2008
Subjects: Environmental Economics and Policy

description: Regulatory agencies are planning to implement policies targeted at mitigating greenhouse gas emissions (GHG)—e.g., low carbon fuel standards and carbon trading. Biofuels are viewed as a path to achieve these goals. Biofuels, however, pose challenges to regulators because their GHG emissions are site-specific (there are regional differences, as well as technical differences) and uncertain. In this article, we propose methodological improvements to existing methods that yield better estimates for biofuel GHG emissions, and reduce uncertainty. We propose to break the net emissions caused by a regulated site, such as an oil refinery, into two parts: direct and indirect emissions. Direct emissions arise both at and away from the final regulated site, but are directly attributable to the final output. Indirect emissions, on the other hand, are comprised of emissions not traceable to a single entity, but which can be computed from aggregate supply and demand, e.g., indirect land use change (ILUC) emissions due to agricultural expansion. The sum of the site-specific direct emissions and the average indirect emissions is, then, compared to the standard, which is constructed given uncertainty. Such a framework can be implemented in practice given existing data and yet allows flexibility given heterogeneity and uncertainty.
Quantum oscillations in mesoscopic rings and anomalous diffusion
Creators: name: Texier, Christophe
name: Montambaux, Gilles
Publisher: name: arXiv
Year: 2004
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: We consider the weak localization correction to the conductance of a ring connected to a network. We analyze the harmonics content of the Al'tshuler-Aronov-Spivak (AAS) oscillations and we show that the presence of wires connected to the ring is responsible for a behaviour different from the one predicted by AAS. The physical origin of this behaviour is the anomalous diffusion of Brownian trajectories around the ring, due to the diffusion in the wires. We show that this problem is related to the anomalous diffusion along the skeleton of a comb. We study in detail the winding properties of Brownian curves around a ring connected to an arbitrary network. Our analysis is based on the spectral determinant and on the introduction of an effective perimeter probing the different time scales. A general expression of this length is derived for arbitrary networks. More specifically we consider the case of a ring connected to wires, to a square network, and to a Bethe lattice.
description: 17 pages, 7 eps figures
An Assessment of Solvers for Algebraically Stabilized Discretizations of Convection-Diffusion-Reaction Equations
Creators: name: Jha, Abhinav
name: Pártl, Ondřej
name: Ahmed, Naveed
name: Kuzmin, Dmitri
Publisher: name: arXiv
Year: 2021
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics
subject: 65M12, 65M15, 65M60

description: We consider flux-corrected finite element discretizations of 3D convection-dominated transport problems and assess the computational efficiency of algorithms based on such approximations. The methods under investigation include flux-corrected transport schemes and monolithic limiters. We discretize in space using a continuous Galerkin method and $\mathbb{P}_1$ or $\mathbb{Q}_1$ finite elements. Time integration is performed using the Crank-Nicolson method or an explicit strong stability preserving Runge-Kutta method. Nonlinear systems are solved using a fixed-point iteration method, which requires solution of large linear systems at each iteration or time step. The great variety of options in the choice of discretization methods and solver components calls for a dedicated comparative study of existing approaches. To perform such a study, we define new 3D test problems for time-dependent and stationary convection-diffusion-reaction equations. The results of our numerical experiments illustrate how the limiting technique, time discretization and solver impact on the overall performance.
Additional file 1 of Implementation considerations for offering personal genomic risk information to the public: a qualitative study
Creators: name: Smit, Amelia K.
name: Reyes-Marcelino, Gillian
name: Keogh, Louise
name: Dunlop, Kate
name: Newson, Ainsley J.
name: Cust, Anne E.
Publisher: name: figshare
Year: 2020
Subjects: subject: Medicine
subject: Biotechnology
subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: Sociology
subject: FOS: Sociology
subject: 69999 Biological Sciences not elsewhere classified
subject: FOS: Biological sciences
subject: Cancer
subject: Science Policy
subject: 110309 Infectious Diseases
subject: FOS: Health sciences

description: Additional file 1. Interview guide questions specific to implementation considerations. This table contains the subset of questions from the interview guide specific to implementation considerations.
Perturbative corrections to semileptonic b decay distributions
Creators: name: Aquila, V.
name: Gambino, P.
name: Ridolfi, G.
name: Uraltsev, N.
Publisher: name: arXiv
Year: 2005
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We compute O(alpha_s) and O(alpha_s^n beta_0^{n-1}) (BLM) corrections to the five structure functions relevant for b->q l nu decays and apply the results to the moments of a few distributions of phenomenological importance. We present compact analytic one-loop formulae for the structure functions, with proper subtraction of the soft divergence.
description: 23 pages, LaTex. A number of textual changes are added for clarity, a missing definition is provided
The Water Quality Effects of Corn Ethanol vs Switchgrass Based Biofuels in the Midwest
Creators: name: Secchi, Silvia
name: Gassman, Philip W.
name: Jha, Manoj K.
name: Kurkalova, Lyubov A.
name: Kling, Catherine L.
name: Secchi, Silvia
name: Gassman, Philip W.
name: Jha, Manoj K.
name: Kurkalova, Lyubov A.
name: Kling, Catherine L.
Publisher: name: Unknown
Year: 2008
Subjects: Crop Production/Industries
Environmental Economics and Policy
Resource /Energy Economics and Policy

description: While biofuels may yield renewable fuel benefits, there could be downsides in terms of water quality and other environmental stressors, particularly if corn is relied upon exclusively as the feedstock. In this article, we describe a modeling system that links agricultural land use decisions in the Upper Mississippi River Basin (UMRB) to economic drivers. This modeling system is then used to assess several scenarios to identify the water quality effects of alternative land uses and the impacts of introducing on the landscape alternative feedstocks, such as switchgrass, to support renewable energy goals. Specifically, a scenario that assesses the water quality effects associated with an increase in corn acreage due to higher relative corn prices provides an estimate of the water quality effects that current biofuel policies may have in the UMRB. Since cellulosic alternatives such as switchgrass are not currently technologically feasible, we undertake two additional scenarios to assess the prices needed to induce switchgrass production in the watershed and the associated water quality changes. Switchgrass production has sizable benefits in terms of sediment and phosphorus losses, though targeting does little to improve sediment over the unrestricted location of switchgrass. Nitrate losses are still high, likely because of the high fertilization levels assumed. Our analysis can help evaluate the costs and environmental impacts associated with implementation strategies for the biofuel mandates of the new energy bill.
Generalized entropy arising from a distribution of q-indices
Creators: name: Tsekouras, Giorgos-Artemios
name: Tsallis, Constantino
Publisher: name: arXiv
Year: 2004
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: It is by now well known that the Boltzmann-Gibbs (BG) entropy $S_{BG}=-k\sum_{i=1}^W p_i \ln p_i$ can be usefully generalized into the entropy $S_q=k (1-\sum_{i=1}^Wp_i^{q}) / (q-1)$ ($q\in \mathcal{R}; S_1=S_{BG}$). Microscopic dynamics determines, given classes of initial conditions, the occupation of the accessible phase space (or of a symmetry-determined nonzero-measure part of it), which in turn appears to determine the entropic form to be used. This occupation might be a uniform one (the usual {\it equal probability hypothesis} of BG statistical mechanics), which corresponds to $q=1$; it might be a free-scale occupancy, which appears to correspond to $q \ne 1$. Since occupancies of phase space more complex than these are surely possible in both natural and artificial systems, the task of further generalizing the entropy appears as a desirable one, and has in fact been already undertaken in the literature. To illustrate the approach, we introduce here a quite general entropy based on a distribution of $q$-indices thus generalizing $S_q$. We establish some general mathematical properties for the new entropic functional and explore some examples. We also exhibit a procedure for finding, given any entropic functional, the $q$-indices distribution that produces it. Finally, on the road to establishing a quite general statistical mechanics, we briefly address possible generalized constraints under which the present entropy could be extremized, in order to produce canonical-ensemble-like stationary-state distributions for Hamiltonian systems.
description: 14 pages including 3 figures
Inverse problem for the Rayleigh system with spectral data
Creators: name: de Hoop, Maarten V.
name: Iantchenko, Alexei
Publisher: name: arXiv
Year: 2021
Subjects: subject: Analysis of PDEs (math.AP)
subject: Mathematical Physics (math-ph)
subject: Spectral Theory (math.SP)
subject: Geophysics (physics.geo-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 35P99, 35Q86, 35J10, 34L05, 34L40, 34L25

description: We analyze an inverse problem associated with the time-harmonic Rayleigh system on a flat elastic half-space concerning the recovery of Lamé parameters in a slab beneath a traction-free surface. We employ the Markushevich substitution, while the data are captured in a Jost function, and point out parallels with a corresponding problem for the Schrödinger equation. The Jost function can be identified with spectral data. We derive a Gel'fand-Levitan type equation and obtain uniqueness with two distinct frequencies.
description: 51 pages
Valley and spin polarized broken symmetry states of interacting electrons in gated MoS$_2$ quantum dots
Creators: name: Szulakowska, Ludmila
name: Cygorek, Moritz
name: Bieniek, Maciej
name: Hawrylak, Pawel
Publisher: name: arXiv
Year: 2020
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Understanding strongly interacting electrons enables the design of materials, nanostructures and devices. Developing this understanding relies on the ability to tune and control electron-electron interactions by, e.g., confining electrons to atomically thin layers of 2D crystals with reduced screening. The interplay of strong interactions on a hexagonal lattice with two nonequivalent valleys, topological moments, and the Ising-like spin-orbit interaction gives rise to a variety of phases of matter corresponding to valley and spin polarized broken symmetry states. In this work we describe a highly tunable strongly interacting system of electrons laterally confined to monolayer transition metal dichalcogenide MoS$_2$ by metalic gates. We predict the existence of valley and spin polarized broken symmetry states tunable by the parabolic confining potential using exact diagonalization techniques for up to $N=6$ electrons. We find that the ground state is formed by one of two phases, either both spin and valley polarized or valley unpolarised but spin intervalley antiferromagnetic, which compete as a function of electronic shell spacing. This finding can be traced back to the combined effect of Ising-like spin-orbit coupling and weak intervalley exchange interaction. These results provide an explanation for interaction-driven symmetry-breaking effects in valley systems and highlight the important role of electron-electron interactions for designing valleytronic devices.
Finite-key analysis for memory-assisted decoy-state quantum key distribution
Creators: name: Currás-Lorenzo, Guillermo
name: Razavi, Mohsen
Publisher: name: arXiv
Year: 2020
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Memory-assisted quantum key distribution (MA-QKD) systems are among novel promising solutions that can improve the key-rate scaling with channel loss. By using a middle node with quantum storage and measurement functionalities, they offer the same key-rate scaling with distance as a single-node quantum repeater. However, the distance at which they can surpass the nominal key rate of repeaterless systems, in terms of bits per second, is typically long, owing to the efficiency and/or interaction time issues when one deals with quantum memories. This crossover distance can be a few hundred kilometres, for instance, when one relies on the exchange of infinitely many key bits for the key-rate analysis. In a realistic setup, however, we should account for the finite-key effects in our analysis. Here, we show that accounting for such effects would actually favour MA-QKD setups, by reducing the crossover distance to the regime where realistic implementations can take place. We demonstrate this by rigorously analysing a decoy-state version of MA-QKD, in the finite-key regime, using memory parameters already achievable experimentally. This provides us with a better understanding of the advantages and challenges of working with memory-based systems.
description: 23 pages, 4 figures. v2: Updated to accepted version
The Impact of Biotech Corn Traits on Ethanol Production
Creators: name: Kalaitzandonakes, Nicholas G.
name: Kaufman, James
name: Meyer, Seth D.
name: Thompson, Wyatt
name: Kalaitzandonakes, Nicholas G.
name: Kaufman, James
name: Meyer, Seth D.
name: Thompson, Wyatt
Publisher: name: Unknown
Year: 2008
Subjects: Crop Production/Industries

description: The U.S. appears committed to the ongoing use of ethanol biofuels. In order to realize the desired benefits, ethanol production must continue to become more efficient. Although many technologies have emerged to improve efficiency this article focuses on the role that corn biotechnology might play. Biotechnology offers the potential to increase yields and lower input use as well as aid the conversion of corn to ethanol. This could have a meaningful impact on the energy balance and greenhouse gas emissions of ethanol production. This article finds those impacts to be significant, although likely to be eclipsed by cellulosic biofuels. However, the realization of any such benefits is conditioned by prevailing market and policy conditions. In a world where the market is less constrained by policy, increased yields afforded through biotechnology would increase corn production, which leads to lower corn price and larger ethanol production volume. When expected policies, most notably the Renewable Fuel Standard, are considered the impacts of biotechnology change. The Renewable Fuel Standard effectively limits the amount of corn based ethanol that is consumed as it shifts production towards cellulosic feedstocks. Despite the increase in corn production and reduced corn price there are only marginal increases in ethanol production volume. Accordingly, the RFSs support of competing biofuels might limit some dimensions of the ethanol industry including its ability to fully benefit from corn biotechnologies.
Towards a Microscopic Model of Magnetoelectric Interactions in Ni3V2O8
Creators: name: Harris, A. B.
name: Yildirim, T.
name: Aharony, A.
name: Entin-Wohlman, O.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We develop a microscopic magnetoelectric coupling in Ni$_3$V$_2$O$_8$ (NVO) which gives rise to the trilinear phenomenological coupling used previously to explain the phase transition in which magnetic and ferroelectric order parameters appear simultaneously. Using combined neutron scattering measurements and first-principles calculations of the phonons in NVO, we determine eleven phonons which can induce the observed spontaneous polarization. Among these eleven phonons, we find that a few of them can actually induce a significant dipole moment. Using the calculated atomic charges, we find that the required distortion to induce the observed dipole moment is very small (~0.001 Å) and therefore it would be very difficult to observe the distortion by neutron-powder diffraction. Finally, we identify the derivatives of the exchange tensor with respect to atomic displacements which are needed for a microscopic model of a spin-phonon coupling in NVO and which we hope will be obtained from a fundamental quantum calculation such as LDA+U. We also analyze two toy models to illustrate that the Dzyaloskinskii-Moriya interaction is very important for coexisting of magnetic and ferroelectric order but it is not the only mechanism when the local site symmetry of the system is low enough.
description: 20 pages, 10 figures