cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Spectropolarimetry and photometry of the early afterglow of the gamma-ray burst GRB191221B
Creators: name: Buckley, D. A. H.
name: Bagnulo, S.
name: Britto, R. J.
name: Mao, J.
name: Kann, D. A.
name: Cooper, J.
name: Lipunov, V.
name: Hewitt, D. M.
name: Razzaque, S.
name: Kuin, N. P. M.
name: Monageng, I. M.
name: Covino, S.
name: Jakobsson, P.
name: van der Horst, A. J.
name: Wiersema, K.
name: Böttcher, M.
name: Campana, S.
name: D'Elia, V.
name: Gorbovskoy, E. S.
name: Gorbunov, I.
name: Groenewald, D. N.
name: Hartmann, D. H.
name: Kornilov, V. G.
name: Mundell, C. G.
name: Podesta, R.
name: Thomas, J. K.
name: Tyurina, N.
name: Vlasenko, D.
name: van Soelen, B.
name: Xu, D.
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We report on results of spectropolarimetry of the afterglow of the long gamma-ray burst GRB 191221B, obtained with SALT/RSS and VLT/FORS2, as well as photometry from two telescopes in the MASTER Global Robotic Network, at the MASTER-SAAO (South Africa) and MASTER-OAFA (Argentina) stations. Prompt optical emission was detected by MASTER-SAAO 38 s after the alert, which dimmed from a magnitude (white-light) of ~10 to 16.2 mag over a period of ~10 ks, followed by a plateau phase lasting ~10 ks and then a decline to ~18 mag after 80 ks. The light curve shows complex structure, with four or five distinct breaks in the power-law decline rate. SALT/RSS linear spectropolarimetry of the afterglow began ~2.9 h after the burst, during the early part of the plateau phase of the light curve. Absorption lines seen at ~6010 Å and 5490 Å are identified with the Mg II 2799 Å line from the host galaxy at z=1.15 and an intervening system located at z=0.96. The mean linear polarisation measured over 3400-8000 Å was ~1.5% and the mean equatorial position angle theta ~65 degrees. VLT/FORS2 spectropolarimetry was obtained ~10 h post-burst, during a period of slow decline (alpha = -0.44), and the polarisation was measured to be p = 1.2% and theta = 60 degrees. Two observations with the MeerKAT radio telescope, taken 30 and 444 days after the GRB trigger, detected radio emission from the host galaxy only. We interpret the light curve and polarisation of this long GRB in terms of a slow-cooling forward-shock.
description: Accepted for publication in MNRAS on 19 June 2021; 14 pages, 6 figures
VALUING AGRICULTURAL MORTGAGE-BACKED SECURITIES
Creators: name: Stokes, Jeffrey R.
name: Brinch, Brian M.
name: Stokes, Jeffrey R.
name: Brinch, Brian M.
Publisher: name: Unknown
Year: 2001
Subjects: subject: Agricultural Finance
subject: agricultural mortgage-backed securities
subject: default
subject: dynamic programming
subject: simulation
subject: prepayment

description: A model to value Federal Agricultural Mortgage Corporation (Farmer Mac) agricultural mortgage-backed securities (AMBS) is developed and numerically solved. The results suggest prepayment penalties currently being used by Farmer Mac reduce yields on AMBS considerably. Even with prepayment penalties, it can be advantageous for profit maximizing mortgagors to optimally prepay or even default on agricultural mortgages. The model is used to quantify prepayment and default risk by valuing the embedded options in the mortgages. Monte Carlo simulation is also used to determine the probability to optimal prepayment given the term structure assumption used to develop the model.
RISK BALANCING IN AN INTEGRATED FARM RISK MANAGEMENT PLAN
Creators: name: Escalante, Cesar L.
name: Barry, Peter J.
name: Escalante, Cesar L.
name: Barry, Peter J.
Publisher: name: Unknown
Year: 2001
Subjects: subject: Farm Management
subject: business risk
subject: expected utility-mean variance framework
subject: financial risk
subject: multiperiod quadratic programming model
subject: Risk Balancing Hypothesis

description: Using optimization techniques in a simulation framework, this study demonstrates the synergy between risk balancing and alternative strategies in effectively reducing risk under changing farm conditions. Highly risk-averse farmers tend to prefer integrated risk-management plans, based on the diversification principle, that yield offsetting combinations of the risk-reducing benefits of most strategies and the profit-generating capacities of the others. The greater appeal of a more diversified plan usually downplays the risk balancing strategy as the farm utilizes credit reserves to implement other production and marketing plans considered essential to overall risk reduction. The farm, however, still realizes overall, although more regulated, reduction in its financial risk position.
Critical dielectric susceptibility at a magnetic BEC quantum critical point
Creators: name: Hayashida, S.
name: Huberich, L.
name: Flavián, D.
name: Yan, Z.
name: Povarov, K. Yu.
name: Gvasaliya, S.
name: Zheludev, A.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Magnetic-field-induced phase transitions are investigated in the frustrated gapped quantum paramagnet Rb$_{2}$Cu$_{2}$Mo$_3$O$_{12}$ through dielectric and calorimetric measurements on single-crystal samples. It is clarified that the previously reported dielectric anomaly at 8~K in powder samples is not due to a chiral spin liquid state as has been suggested, but rather to a tiny amount of a ferroelectric impurity phase. Two field-induced quantum phase transitions between paraelectric and paramagnetic and ferroelectric and magnetically ordered states are clearly observed. It is shown that the electric polarization is a secondary order parameter at the lower-field (gap closure) quantum critical point but a primary one at the saturation transition. Having clearly identified the magnetic Bose-Einstein condensation (BEC) nature of the latter, we use the dielectric channel to directly measure the critical divergence of BEC susceptibility. The observed power-law behavior is in very good agreement with theoretical expectations for three-dimensional BEC. Finally, dielectric data reveal magnetic presaturation phases in this compound that may feature exotic order with unconventional broken symmetries.
TAX INCENTIVES: AN EFFECTIVE DEVELOPMENT STRATEGY FOR RURAL COMMUNITIES?
Creators: name: Rainey, Daniel V.
name: McNamara, Kevin T.
name: Rainey, Daniel V.
name: McNamara, Kevin T.
Publisher: name: Unknown
Year: 2002
Subjects: subject: Community/Rural/Urban Development
subject: agglomeration
subject: rural development
subject: tax policy

description: As national and local economies become more globalized, many rural areas are going to find it more difficult to compete for private capital investments. A traditional tool, modifications to tax policy, of state and local governments will not be as effective (for many communities it has never been effective) in the future. These communities will need to seek other avenues of growth. However, for many rural communities even alternative avenues will not lead to enhanced economic opportunity.
Do observations prove that cosmological neutrinos are thermally distributed?
Creators: name: Cuoco, A.
name: Lesgourgues, J.
name: Mangano, G.
name: Pastor, S.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: It is usually assumed that relic neutrinos possess a Fermi-Dirac distribution, acquired during thermal equilibrium in the Early Universe. However, various mechanisms could introduce strong distortions in this distribution. We perform a Bayesian likelihood analysis including the first moments of the three active neutrino distributions as free parameters, and show that current cosmological observations of light element abundances, Cosmic Microwave Background (CMB) anisotropies and Large Scale Structures (LSS) are compatible with very large deviations from the standard picture. We also calculate the bounds on non-thermal distortions which can be expected from future observations, and stress that CMB and LSS data alone will not be sensitive enough in order to distinguish between non-thermal distortions in the neutrino sector and extra relativistic degrees of freedom. This degeneracy could be removed by additional constraints from primordial nucleosynthesis or independent neutrino mass scale measurements.
description: 12 pages, 4 figures
EXCHANGE RATE EFFECTS ON AGRICULTURAL TRADE
Creators: name: Orden, David
name: Orden, David
Publisher: name: Unknown
Year: 2002
Subjects: subject: International Relations/Trade
subject: agricultural policy
subject: agricultural trade
subject: exchange rate

description: With sustained appreciation of the U.S. dollar over the past 4 years, the exchange rate has again taken on importance for agriculture. This overview paper revisits the analysis of exchange rate impacts, reviewing the relevant conceptual arguments, summarizing the evidence economists and agricultural economists have marshaled from the 1970s and the 1980s and from several more recent papers, presenting some illustrative recent empirical analysis of exchange rate effects, and briefly examining the detrimental consequences that sustained appreciation of the dollar is having on U.S. farm policy.
WOMEN'S ASSETS AND INTRAHOUSEHOLD ALLOCATION IN RURAL BANGLADESH: TESTING MEASURES OF BARGAINING POWER
Creators: name: Quisumbing, Agnes R.
name: De La Briere, Benedicte
name: Quisumbing, Agnes R.
name: De La Briere, Benedicte
Publisher: name: Unknown
Year: 2000
Subjects: Consumer/Household Economics

description: This paper examines how differences in the bargaining power of husband and wife affect the distribution of consumption expenditures in rural Bangladeshi households. Two alternative measures of assets are used: current assets and the value of assets brought to marriage. Results show that both assets at marriage and current assets are strongly determined by the human capital of husband and wife and the characteristics of their origin families. For both husband and wife, parents’ landholdings are a consistent determinant of both assets at marriage and current assets. Contrary to the unitary model, husband’s and wife’s assets have different effects on the allocation of expenditures within the household. Wife’s assets have a positive and significant effect on the share of expenditures on children’s clothing and education. This result is robust to the choice of asset measure and estimation procedure. After endogeneity of assets is accounted for, husband’s current assets have a positive and significant effect on the food expenditure share. Neglecting the endogeneity of asset measures to individual and parental characteristics may lead to biased estimates of the impact of men’s and women’s assets on expenditure shares.
ARE NEIGHBORS EQUAL? ESTIMATING LOCAL INEQUALITY IN THREE DEVELOPING COUNTRIES
Creators: name: Elbers, Chris
name: Lanjouw, Peter
name: Mistiaen, Johan A.
name: Ozler, Berk
name: Simler, Kenneth R.
name: Elbers, Chris
name: Lanjouw, Peter
name: Mistiaen, Johan A.
name: Ozler, Berk
name: Simler, Kenneth R.
Publisher: name: Unknown
Year: 2003
Subjects: Labor and Human Capital

description: A methodology to produce disaggregated estimates of inequality is implemented in three developing countries: Ecuador, Madagascar, and Mozambique. These inequality estimates are decomposed into progressively more disaggregated spatial units and the results in all three countries are suggestive that even at a very high level of spatial disaggregation, the contribution of within-community inequality to overall inequality remains very high. The results also indicate there is a considerable amount of variation across communities in all three countries. The basic correlates of local-level inequality are explored, and it is consistently found that geographic characteristics are strongly correlated with inequality, even after controlling for demographic and economic conditions.
Controlling Nonlinear Stochastic Resonance by Harmonic Mixing
Creators: name: Schmid, Gerhard
name: Hanggi, Peter
Publisher: name: arXiv
Year: 2006
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We investigate the potential for controlling the effect of nonlinear Stochastic Resonance (SR) by use of harmonic mixing signals for an overdamped Brownian dynamics in a symmetric double well potential. The periodic forcing for harmonic mixing consists of a first signal with a basic frequency $Ω$ and a second, superimposed signal oscillating at twice the basic frequency $2Ω$. By variation of the phase difference between these two components and the amplitude ratios of the driving the phenomenon of SR becomes a priori controllable. The harmonic mixing dynamically breaks the symmetry so that the time- and ensemble-average assumes a non-vanishing value. Independently of the noise level, the response can be suppressed by adjusting the phase difference. Nonlinear SR then exhibits resonances at higher harmonics with respect to the applied noise strength and relative phase. The scheme of nonlinear SR via harmonic mixing can be used to steer the nonlinear response and to sensitively measure the internal noise strength. We further demonstrate that the full Fokker-Planck dynamics can be well approximated by a two-state model.
description: 13 pages, 4 figures
EVALUATING TRANSFER PROGRAMS WITHIN A GENERAL EQUILIBRIUM FRAMEWORK
Creators: name: Coady, David P.
name: Harris, Rebecca Lee
name: Coady, David P.
name: Harris, Rebecca Lee
Publisher: name: Unknown
Year: 2001
Subjects: Institutional and Behavioral Economics

description: We set out a general equilibrium model for the evaluation of a domestically financed transfer program, which helps to combine the results from a computable general equilibrium model with disaggregated household data. We separate the indirect welfare impact into three components: (1) the redistribution effect arising from the need to finance programs, (2) the reallocative effect arising from the transfer of resources between households with different “tax propensities,” and (3) the distortionary effect arising from the need to use distortionary finance instruments. We show how all these effects can be usefully subsumed within one parameter, namely, the cost of public funds. Using a Mexican cash transfer program as an illustration, we use the approach to show that the substantial welfare gains that result from the switch from universal food subsidies to targeted cash transfers reflect both the improved targeting efficiency of the latter as well as a relaxation of the trade-off between equity and efficiency objectives when designing tax systems. More generally, the indirect costs of finance can be substantially lowered when such programs are combined with appropriate tax reforms.
IN-KIND TRANSFERS AND HOUSEHOLD FOOD CONSUMPTION: IMPLICATIONS FOR TARGETED FOOD PROGRAMS IN BANGLADESH
Creators: name: Del Ninno, Carlo
name: Dorosh, Paul A.
name: Del Ninno, Carlo
name: Dorosh, Paul A.
Publisher: name: Unknown
Year: 2002
Subjects: Food Consumption/Nutrition/Food Safety

description: This paper examines the impact of wheat transfers and cash incomes on wheat consumption and wheat markets. Using propensity score- matching techniques, the total marginal propensity to consume (MPC) for wheat is, on average, 0.33, ranging from essentially zero for Food For Work (a program with large transfers) to 0.51 for Food For Education. Econometric estimates indicate that the MPC for small wheat transfers to poor households is approximately 0.25, while the MPC for wheat out of cash income is near zero. This increase in demand for wheat reduces the potential price effect of three major targeted programs involving small rations (Food For Education, Vulnerable Group Development, and Vulnerable Group Feeding) by about one-third.
Search for neutral MSSM Higgs bosons decaying to tau pairs in p-pbar collisions at sqrt(s)=1.96 TeV
Creators: name: CDF Collaboration
Publisher: name: arXiv
Year: 2005
Subjects: subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: We present a search for neutral supersymmetric Higgs bosons decaying to tau pairs produced in p-pbar collisions at sqrt(s) = 1.96 TeV. The data, corresponding to 310 pb^(-1) integrated luminosity, were collected with the CDF II detector at the Tevatron collider at Fermilab. No significant excess above the standard model backgrounds is observed. We set exclusion limits on the production cross section times branching fraction to tau pairs for Higgs masses in the range from 90 to 250 GeV/c^2.
description: 7 pages, 4 figures. Submitted to PRL
Electroweak Phase Transition with an SU(2) Dark Sector
Creators: name: Ghosh, Tathagata
name: Guo, Huai-Ke
name: Han, Tao
name: Liu, Hongkai
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We consider a non-Abelian dark SU(2)$_{\rm D}$ model where the dark sector couples to the Standard Model (SM) through a Higgs portal. We investigate two different scenarios of the dark sector scalars with $Z_2$ symmetry, with Higgs portal interactions that can introduce mixing between the SM Higgs boson and the SM singlet scalars in the dark sector. We utilize the existing collider results of the Higgs signal rate, direct heavy Higgs searches, and electroweak precision observables to constrain the model parameters. The $\text{SU(2)}_{\text{D}}$ partially breaks into $\text{U(1)}_{\text{D}}$ gauge group by the scalar sector. The resulting two stable massive dark gauge bosons and pseudo-Goldstone bosons can be viable cold dark matter candidates, while the massless gauge boson from the unbroken $\text{U(1)}_{\text{D}}$ subgroup is a dark radiation and can introduce long-range attractive dark matter (DM) self-interaction, which can alleviate the small-scale structure issues. We study in detail the pattern of strong first-order phase transition and gravitational wave (GW) production triggered by the dark sector symmetry breaking, and further evaluate the signal-to-noise ratio for several proposed space interferometer missions. We conclude that the rich physics in the dark sector may be observable with the current and future measurements at colliders, DM experiments, and GW interferometers.
description: 40 pages, 10 figures, 3 tables
Analysing Twitter Semantic Networks: the case of 2018 Italian Elections
Creators: name: Radicioni, Tommaso
name: Saracco, Fabio
name: Pavan, Elena
name: Squartini, Tiziano
Publisher: name: arXiv
Year: 2020
Subjects: subject: Social and Information Networks (cs.SI)
subject: Applied Physics (physics.app-ph)
subject: FOS: Computer and information sciences
subject: FOS: Physical sciences

description: Social media play a key role in shaping citizens' political opinion. According to the Eurobarometer, the percentage of EU citizens employing online social networks on a daily basis has increased from 18% in 2010 to 48% in 2019. The entwinement between social media and the unfolding of political dynamics has motivated the interest of researchers for the analysis of users online behavior - with particular emphasis on group polarization during debates and echo-chambers formation. In this context, attention has been predominantly directed towards the study of online relations between users while semantic aspects have remained under-explored. In the present paper, we aim at filling this gap by adopting a two-steps approach. First, we identify the discursive communities animating the political debate in the run up of the 2018 Italian Elections as groups of users with a significantly-similar retweeting behavior. Second, we study the semantic mechanisms that shape their internal discussions by monitoring, on a daily basis, the structural evolution of the semantic networks they induce. Above and beyond specifying the semantic peculiarities of the Italian electoral competition, our approach innovates studies of online political discussions in two main ways. On the one hand, it grounds semantic analysis within users' behaviors by implementing a method, rooted in statistical theory, that guarantees that our inference of socio-semantic structures is not biased by any unsupported assumption about missing information; on the other, it is completely automated as it does not rest upon any manual labelling (either based on the users' features or on their sharing patterns). These elements make our method applicable to any Twitter discussion regardless of the language or the topic addressed.
What is novel in quantum transport for mesoscopics?
Creators: name: Das, Mukunda P
name: Green, Frederick
Publisher: name: arXiv
Year: 2005
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: The understanding of mesoscopic transport has now attained an ultimate simplicity. Indeed, orthodox quantum kinetics would seem to say little about mesoscopics that has not been revealed - nearly effortlessly - by more popular means. Such is far from the case, however. The fact that kinetic theory remains very much in charge is best appreciated through the physics of a quantum point contact. While discretization of its conductance is viewed as the exclusive result of coherent, single-electron-wave transmission, this does not begin to address the paramount feature of all metallic conduction: dissipation. A perfect quantum point contact still has finite resistance, so its ballistic carriers must dissipate the energy gained from the applied field. How do they manage that? The key is in standard many-body quantum theory, and its conservation principles.
description: 10 pp, 3 figs. Invited talk at 50th Golden Jubilee DAE Symposium, BARC, Mumbai, 2005
Mohave I
Creators: name: Crawford, Judith G.
name: Martin, Robert
name: Sinyella, Lorenzo
Publisher: name: California Language Archive, University of California, Berkeley
Year: 2015
Subjects: subject: mov
subject: Mojave language
subject: yuf
subject: Havasupai language

description: Second of 14 Yuman field notebooks. Labeled "Book #2". Mainly elicited vocabulary.
Olympus: a benchmarking framework for noisy optimization and experiment planning
Creators: name: Häse, Florian
name: Aldeghi, Matteo
name: Hickman, Riley J.
name: Roch, Loïc M.
name: Christensen, Melodie
name: Liles, Elena
name: Hein, Jason E.
name: Aspuru-Guzik, Alán
Publisher: name: arXiv
Year: 2020
Subjects: subject: Machine Learning (stat.ML)
subject: Machine Learning (cs.LG)
subject: Chemical Physics (physics.chem-ph)
subject: FOS: Computer and information sciences
subject: FOS: Physical sciences

description: Research challenges encountered across science, engineering, and economics can frequently be formulated as optimization tasks. In chemistry and materials science, recent growth in laboratory digitization and automation has sparked interest in optimization-guided autonomous discovery and closed-loop experimentation. Experiment planning strategies based on off-the-shelf optimization algorithms can be employed in fully autonomous research platforms to achieve desired experimentation goals with the minimum number of trials. However, the experiment planning strategy that is most suitable to a scientific discovery task is a priori unknown while rigorous comparisons of different strategies are highly time and resource demanding. As optimization algorithms are typically benchmarked on low-dimensional synthetic functions, it is unclear how their performance would translate to noisy, higher-dimensional experimental tasks encountered in chemistry and materials science. We introduce Olympus, a software package that provides a consistent and easy-to-use framework for benchmarking optimization algorithms against realistic experiments emulated via probabilistic deep-learning models. Olympus includes a collection of experimentally derived benchmark sets from chemistry and materials science and a suite of experiment planning strategies that can be easily accessed via a user-friendly python interface. Furthermore, Olympus facilitates the integration, testing, and sharing of custom algorithms and user-defined datasets. In brief, Olympus mitigates the barriers associated with benchmarking optimization algorithms on realistic experimental scenarios, promoting data sharing and the creation of a standard framework for evaluating the performance of experiment planning strategies
description: 15 pages, 4 figures, 4 tables (with SI: 22 pages, 11 figures, 15 tables). Changes: minor fixes to text and references. Two paragraphs added in Sec. III
STRENGTHENING PUBLIC SAFETY NETS: CAN THE INFORMAL SECTOR SHOW THE WAY?
Creators: name: Morduch, Jonathan
name: Sharma, Manohar P.
name: Morduch, Jonathan
name: Sharma, Manohar P.
Publisher: name: Unknown
Year: 2001
Subjects: Public Economics

description: The worsening degradation of natural resources urgently requires the adoption of more sustainable management practices. This need has led to growing interest and investment in monitoring systems for tracking the condition of natural resources. Although grounded in concepts of sustainability, the application of monitoring systems has progressed little beyond the identification and measurement of large numbers of potentially interesting indicators. Most monitoring activities are also passive and do not lead to the changes needed to rectify the problems they identify. Too often monitoring becomes an end in itself and an expensive claim on public funds. This study is concerned with the design of monitoring systems that have direct relevance for the management of natural resources. We call these Policy Relevant Monitoring Systems (PRMS). Such systems have several key characteristics. They provide: a) a decision framework for selecting resource problems to monitor that offer potentially large social payoffs relative to the costs of monitoring, b) timely, including early warning information on emerging problems, c) a means of identifying the causes of an emerging problem, d) an analytical framework for identifying options for corrective action, e) an institutional framework for achieving ownership among key stakeholders (the resource users and those affected by the resource use) and agreement about emerging problems, the corrective actions to take, and effective implementation, and f) a built-in mechanism for learning from past experience to improve the performance of the monitoring system over time. The design and implementation of a PRMS is complicated in reality by the presence of multiple resource users with often conflicting interests, and by the presence of environmental externalities. The approach is developed and illustrated through detailed examination of the Arenal-Tempisque watershed in Costa Rica. This watershed exhibits classic multiple user and externality problems: deforestation by dairy and cattle farmers in the upper watershed leads to soil erosion and siltation of the various reservoirs that feed an important hydro-electric power generation system, and agro-chemical use by irrigated farmers has adverse impacts on a highly valued wetlands park and on wildlife and fishing in the lower reaches of the watershed.
Emergence of oscillons in kink-impurity interactions
Creators: name: Lizunova, Mariya
name: Kager, Jasper
name: de Lange, Stan
name: van Wezel, Jasper
Publisher: name: arXiv
Year: 2020
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: Pattern Formation and Solitons (nlin.PS)
subject: FOS: Physical sciences

description: The (1+1)-dimensional classical $φ^4$ theory contains stable, topological excitations in the form of solitary waves or kinks, as well as stable but non-topological solutions, such as the oscillon. Both are used in effective descriptions of excitations throughout myriad fields of physics. The oscillon is well-known to be a coherent, particle-like solution when introduced as an Ansatz in the $φ^4$ theory. Here, we show that oscillons also arise naturally in the dynamics of the theory, in particular as the result of kink-antikink collisions in the presence of an impurity. We show that in addition to the scattering of kinks and the formation of a breather, both bound oscillon pairs and propagating oscillons may emerge from the collision. We discuss their resonances and critical velocity as a function of impurity strength and highlight the role played by the impurity in the scattering process.
description: 5 pages, 5 figures; final version
Flow Equations for Disordered Floquet Systems
Creators: name: Thomson, S. J.
name: Magano, D.
name: Schiró, M.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: In this work, we present a new approach to disordered, periodically driven (Floquet) quantum many-body systems based on flow equations. Specifically, we introduce a continuous unitary flow of Floquet operators in an extended Hilbert space, whose fixed point is both diagonal and time-independent, allowing us to directly obtain the Floquet modes. We first apply this method to a periodically driven Anderson insulator, for which it is exact, and then extend it to driven many-body localized systems within a truncated flow equation ansatz. In particular we compute the emergent Floquet local integrals of motion that characterise a periodically driven many-body localized phase. We demonstrate that the method remains well-controlled in the weakly-interacting regime, and allows us to access larger system sizes than accessible by numerically exact methods, paving the way for studies of two-dimensional driven many-body systems.
description: 40 pages, 10 figures
Real-time gravitational replicas: Formalism and a variational principle
Creators: name: Colin-Ellerin, Sean
name: Dong, Xi
name: Marolf, Donald
name: Rangamani, Mukund
name: Wang, Zhencheng
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: This work is the first step in a two-part investigation of real-time replica wormholes. Here we study the associated real-time gravitational path integral and construct the variational principle that will define its saddle-points. We also describe the general structure of the resulting real-time replica wormhole saddles, setting the stage for construction of explicit examples. These saddles necessarily involve complex metrics, and thus are accessed by deforming the original real contour of integration. However, the construction of these saddles need not rely on analytic continuation, and our formulation can be used even in the presence of non-analytic boundary-sources. Furthermore, at least for replica- and CPT-symmetric saddles we show that the metrics may be taken to be real in regions spacelike separated from a so-called `splitting surface'. This feature is an important hallmark of unitarity in a field theory dual.
description: 41 pages, 10 tikz and pdf figures. v2: added references. v3: typos fixed, published version. v4: minor clarifications
Chandra and XMM-Newton observations of the exceptional pulsar PSR B0628-28
Creators: name: Tepedelenlioglu, E.
name: Ogelman, H.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: PSR B0628-28 is a radio pulsar which was first detected in the X-ray band by ROSAT and then later observed with Chandra and XMM-Newton. The Chandra observation yielded an X-ray luminosity two orders of magnitude higher than what is expected for spin-powered pulsars, also there were no pulsations detected. The XMM-Newton observation, however, reveals pulsations at the expected radio period, P=1.244 s. The simultaneously analyzed spectra also gives a luminosity (in cgs) Log Lx=30.34, which is ~350 times greater than what would be expected from the correlation between Lx-Edot.
description: 13 pages, 4 figures, to be published in ApJL
Frequency-Dependent Squeeze Amplitude Attenuation and Squeeze Angle Rotation by Electromagnetically Induced Transparency for Gravitational Wave Interferometers
Creators: name: Mikhailov, Eugeniy E.
name: Goda, Keisuke
name: Corbitt, Thomas
name: Mavalvala, Nergis
Publisher: name: arXiv
Year: 2005
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We study the effects of frequency-dependent squeeze amplitude attenuation and squeeze angle rotation by electromagnetically induced transparency (EIT) on gravitational wave (GW) interferometers. We propose the use of low-pass, band-pass, and high-pass EIT filters, an S-shaped EIT filter, and an intra-cavity EIT filter to generate frequency-dependent squeezing for injection into the antisymmetric port of GW interferometers. We find that the EIT filters have several advantages over the previous filter designs with regard to optical losses, compactness, and the tunability of the filter linewidth.
description: 4 pages
Additive-multiplicative stochastic models of financial mean-reverting processes
Creators: name: Anteneodo, C.
name: Riera, R.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Physics and Society (physics.soc-ph)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Statistical Finance (q-fin.ST)
subject: FOS: Physical sciences
subject: FOS: Economics and business

description: We investigate a generalized stochastic model with the property known as mean reversion, that is, the tendency to relax towards a historical reference level. Besides this property, the dynamics is driven by multiplicative and additive Wiener processes. While the former is modulated by the internal behavior of the system, the latter is purely exogenous. We focus on the stochastic dynamics of volatilities, but our model may also be suitable for other financial random variables exhibiting the mean reversion property. The generalized model contains, as particular cases, many early approaches in the literature of volatilities or, more generally, of mean-reverting financial processes. We analyze the long-time probability density function associated to the model defined through a Itô-Langevin equation. We obtain a rich spectrum of shapes for the probability function according to the model parameters. We show that additive-multiplicative processes provide realistic models to describe empirical distributions, for the whole range of data.
description: 8 pages, 3 figures
Generalized master equation for first-passage problems in partitioned spaces
Creators: name: Frömberg, Daniela
name: Höfling, Felix
Publisher: name: arXiv
Year: 2020
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Biological Physics (physics.bio-ph)
subject: Chemical Physics (physics.chem-ph)
subject: FOS: Physical sciences

description: Motivated by a range of biological applications related to the transport of molecules in cells, we present a modular framework to treat first-passage problems for diffusion in partitioned spaces. The spatial domains can differ with respect to their diffusivity, geometry, and dimensionality, but can also refer to transport modes alternating between diffusive, driven, or anomalous motion. The approach relies on a coarse-graining of the motion by dissecting the trajectories on domain boundaries or when the mode of transport changes, yielding a small set of states. The time evolution of the reduced model follows a generalized master equation (GME) for non-Markovian jump processes; the GME takes the form of a set of linear integro-differential equations in the occupation probabilities of the states and the corresponding probability fluxes. Further building blocks of the model are partial first-passage time (FPT) densities, which encode the transport behavior in each domain or state. After an outline of the general framework for multiple domains, the approach is exemplified and validated for a target search problem with two domains in one- and three-dimensional space, first by exactly reproducing known results for an artificially divided, homogeneous space, and second by considering the situation of domains with distinct diffusivities. Analytical solutions for the FPT densities are given in Laplace domain and are complemented by numerical backtransforms yielding FPT densities over many decades in time, confirming that the geometry and heterogeneity of the space can introduce additional characteristic time scales.
description: accepted manuscript
Using noise to probe recurrent neural network structure and prune synapses
Creators: name: Moore, Eli
name: Chaudhuri, Rishidev
Publisher: name: arXiv
Year: 2020
Subjects: subject: Neurons and Cognition (q-bio.NC)
subject: Neural and Evolutionary Computing (cs.NE)
subject: FOS: Biological sciences
subject: FOS: Computer and information sciences

description: Many networks in the brain are sparsely connected, and the brain eliminates synapses during development and learning. How could the brain decide which synapses to prune? In a recurrent network, determining the importance of a synapse between two neurons is a difficult computational problem, depending on the role that both neurons play and on all possible pathways of information flow between them. Noise is ubiquitous in neural systems, and often considered an irritant to be overcome. Here we suggest that noise could play a functional role in synaptic pruning, allowing the brain to probe network structure and determine which synapses are redundant. We construct a simple, local, unsupervised plasticity rule that either strengthens or prunes synapses using only synaptic weight and the noise-driven covariance of the neighboring neurons. For a subset of linear and rectified-linear networks, we prove that this rule preserves the spectrum of the original matrix and hence preserves network dynamics even when the fraction of pruned synapses asymptotically approaches 1. The plasticity rule is biologically-plausible and may suggest a new role for noise in neural computation.
The Physics of Core-Collapse Supernovae
Creators: name: Woosley, S.
name: Janka, H. -T.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Supernovae are nature's grandest explosions and an astrophysical laboratory in which unique conditions exist that are not achievable on Earth. They are also the furnaces in which most of the elements heavier than carbon have been forged. Scientists have argued for decades about the physical mechanism responsible for these explosions. It is clear that the ultimate energy source is gravity, but the relative roles of neutrinos, fluid instabilities, rotation and magnetic fields continue to be debated.
description: Review article; 17 pages, 5 figures
Stochastic sampling effects favor manual over digital contact tracing
Creators: name: Mancastroppa, Marco
name: Castellano, Claudio
name: Vezzani, Alessandro
name: Burioni, Raffaella
Publisher: name: arXiv
Year: 2020
Subjects: subject: Physics and Society (physics.soc-ph)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Populations and Evolution (q-bio.PE)
subject: FOS: Physical sciences
subject: FOS: Biological sciences

description: Isolation of symptomatic individuals, tracing and testing of their nonsymptomatic contacts are fundamental strategies for mitigating the current COVID-19 pandemic. The breaking of contagion chains relies on two complementary strategies: manual reconstruction of contacts based on interviews and a digital (app-based) privacy-preserving contact tracing. We compare their effectiveness using model parameters tailored to describe SARS-CoV-2 diffusion within the activity-driven model, a general empirically validated framework for network dynamics. We show that, even for equal probability of tracing a contact, manual tracing robustly performs better than the digital protocol, also taking into account the intrinsic delay and limited scalability of the manual procedure. This result is explained in terms of the stochastic sampling occurring during the case-by-case manual reconstruction of contacts, contrasted with the intrinsically prearranged nature of digital tracing, determined by the decision to adopt the app or not by each individual. The better performance of manual tracing is enhanced by heterogeneity in agent behavior: superspreaders not adopting the app are completely invisible to digital contact tracing, while they can be easily traced manually, due to their multiple contacts. We show that this intrinsic difference makes the manual procedure dominant in realistic hybrid protocols.
description: Main document: 11 pages, 6 figures; Supplementary Information: 18 pages, 5 figures
A new approach to hyperbolic inverse problems
Creators: name: Eskin, Gregory
Publisher: name: arXiv
Year: 2005
Subjects: subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics

description: We present a modification of the BC-method in the inverse hyperbolic problems. The main novelty is the study of the restrictions of the solutions to the characteristic surfaces instead of the fixed time hyperplanes. The main result is that the time-dependent Dirichlet-to-Neumann operator prescribed on a part of the boundary uniquely determines the coefficients of the self-adjoint hyperbolic operator up to a diffeomorphism and a gauge transformation. In this paper we prove the crucial local step. The global step of the proof will be presented in the forthcoming paper.
description: We corrected the proof of the main Lemma 2.1 by assuming that potentials A(x),V(x) are real valued
Electron vortex beams in non-uniform magnetic fields
Creators: name: Melkani, Abhijeet
name: van Enk, S. J.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Quantum Physics (quant-ph)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We consider the quantum theory of paraxial non-relativistic electron beams in non-uniform magnetic fields, such as the Glaser field. We find the wave function of an electron from such a beam and show that it is a joint eigenstate of two ($z$-dependent) commuting gauge-independent operators. This generalized Laguerre-Gaussian vortex beam has a phase that is shown to consist of two parts, each being proportional to the eigenvalue of one of the two conserved operators and each having different symmetries. We also describe the dynamics of the angular momentum and cross-sectional area of any mode and how a varying magnetic field can split a mode into a superposition of modes. By a suitable change in frame of reference all of our analysis also applies to an electron in a quantum Hall system with a time-dependent magnetic field.
description: 8 pages, 1 figure. Comments welcome
A decision support system for real-time hydropower scheduling in a competitive power market environment
Creators: name: Shawwash, Ziad K. Elias
Publisher: name: University of British Columbia
Year: 2009

description: The electricity supply market is rapidly changing from a monopolistic to a competitive environment. Being able to operate their system of reservoirs and generating facilities to get maximum benefits out of existing assets and resources is important to the British Columbia Hydro Authority (B.C. Hydro). A decision support system has been developed to help B.C. Hydro operate their system in an optimal way. The system is operational and is one of the tools that are currently used by the B.C. Hydro system operations engineers to determine optimal schedules that meet the hourly domestic load and also maximize the value B.C. Hydro obtains from spot transactions in the Western U.S. and Alberta electricity markets. This dissertation describes the development and implementation of the decision support system in production mode. The decision support system consists of six components: the input data preparation routines, the graphical user interface (GUI), the communication protocols, the hydraulic simulation model, the optimization model, and the results display software. A major part of this work involved the development and implementation of a practical and detailed large-scale optimization model that determines the optimal tradeoff between the long-term value of water and the returns from spot trading transactions in real-time operations. The postmortem-testing phase showed that the gains in value from using the model accounted for 0.25% to 1.0% o f the revenues obtained. The financial returns from using the decision support system greatly outweigh the costs of building it. Other benefits are the savings in the time needed to prepare the generation and trading schedules. The system operations engineers now can use the time saved to focus on other important aspects of their job. The operators are currently experimenting with the system in production mode, and are gradually gaining confidence that the advice it provides is accurate, reliable and sensible. The main lesson learned from developing and implementing the system was that there is no alternative to working very closely with the intended end-users of the system, and with the people who have deep knowledge, experience and understanding of how the system is and should be operated.
REDUCING CHILD UNDERNUTRITION: HOW FAR DOES INCOME GROWTH TAKE US?
Creators: name: Haddad, Lawrence James
name: Alderman, Harold
name: Appleton, Simon
name: Song, Lina
name: Yohannes, Yisehac
name: Haddad, Lawrence James
name: Alderman, Harold
name: Appleton, Simon
name: Song, Lina
name: Yohannes, Yisehac
Publisher: name: Unknown
Year: 2002
Subjects: Food Consumption/Nutrition/Food Safety

description: How rapidly will child undernutrition respond to income growth? This study explores that question using household survey data from 12 countries. In addition, data on the undernutrition rates since the 1970s available from a cross-section of countries are employed in this investigation. Both forms of analysis yield similar results. Income increases at household and national levels imply similar rates of reduction in undernutrition. Using these estimates and better-than-historical income growth rates, we find that the Millennium Development Goal (MDG) of halving the levels of child underweight by 2015 is unlikely to be met through income growth alone. What is needed is a balanced strategy of income growth and investment in more direct interventions to accelerate reductions in undernutrition.
MOVING FORWARD WUTH COMPLEMENTARY FEEDING: INDICATORS AND RESEARCH PRIORITIES
Creators: name: Ruel, Marie T.
name: Brown, Kenneth H.
name: Caulfield, Laura E.
name: Ruel, Marie T.
name: Brown, Kenneth H.
name: Caulfield, Laura E.
Publisher: name: Unknown
Year: 2003
Subjects: Food Security and Poverty

description: For a number of reasons, progress in improving child feeding practices in the developing world has been remarkably slow. First, complementary feeding practices encompass a number of interrelated behaviors that need to be addressed simultaneously. Child feeding practices are also age-specific within narrow age ranges, which add to the complexity of developing recommendations and measuring responses. Finally, the lack of clear international recommendations for some aspects of complementary feeding has prevented the development of universal indicators to define optimal feeding. Without appropriate measurement tools, the design and evaluation of programs to improve complementary feeding practices cannot move forward. The present paper is the first systematic attempt at filling this gap. It puts forth a framework for the development of indicators of complementary feeding practices and proposes a series of possible indicators to measure some of the most critical aspects of infant and young child feeding. The emphasis is on simple indicators for use in large surveys or in program contexts. Indicators for the following aspects of complementary feeding of 6-23-month-old children are discussed: (1) breastfeeding; (2) energy from complementary foods; (3) nutrient density of complementary foods; and (4) safe preparation and storage of complementary foods. Finally, possible approaches to validate the proposed indicators are discussed and research priorities are highlighted.