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Poisson stochastic master equation unravellings and the measurement problem: a quantum stochastic calculus perspective

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arXiv 2019年

作者： Keys, Dustin Wehr, Jan Program in Applied Mathematics University of Arizona TucsonAZ85721 United States Department of Mathematics and Program in Applied Mathematics University of Arizona TucsonAZ85721 United States

The paper studies a class of quantum stochastic differential equations, modeling an interaction of a system with its environment in the quantum noise approximation. The space representing quantum noise is the symmetric Fock space over L2 (+). Using the isomorphism of this space with the space of square-integrable functionals of the Poisson process, the equations can be represented as classical stochastic differential equations, driven by Poisson processes. This leads to a discontinuous dynamical state reduction which we compare to the Ghirardi-Rimini-Weber model. A purely quantum object, the norm process, is found which plays the role of an observer (in the sense of Everett [H. Everett III, Reviews of modern physics, 29.3, 454, (1957)]), encoding all events occurring in the system space. An algorithm introduced by Dalibard et al [J. Dalibard, Y. Castin, and K. Mølmer, Physical review letters, 68.5, 580 (1992)] to numerically solve quantum master equations is interpreted in the context of unravellings and the trajectories of expected values of system observables are calculated. © 2019, CC BY.

关键词： Poisson distribution

Mahakala: a Python-based Modular Ray-tracing and Radiative Transfer Algorithm for Curved Space-times

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arXiv 2023年

作者： Sharma, Aniket Medeiros, Lia Chan, Chi-Kwan Halevi, Goni Mullen, Patrick D. Stone, James M. Wong, George N. Indian Institute of Science Education and Research Mohali Sector 81 SAS Nagar PO Manauli Punjab Mohali140306 India School of Natural Sciences Institute for Advanced Study 1 Einstein Drive PrincetonNJ08540 United States Steward Observatory Department of Astronomy University of Arizona 933 N. Cherry Ave. TucsonAZ85721 United States Data Science Institute University of Arizona 1230 N. Cherry Ave. TucsonAZ85721 United States Program in Applied Mathematics University of Arizona 617 N. Santa Rita TucsonAZ85721 United States Department of Astrophysical Sciences Princeton University 4 Ivy Lane PrincetonNJ08544 United States CCS-2 Los Alamos National Laboratory Los AlamosNM United States Center for Theoretical Astrophysics Los Alamos National Laboratory Los AlamosNM United States Princeton Gravity Initiative Princeton University PrincetonNJ08544 United States

We introduce Mahakala, a Python-based, modular, radiative ray-tracing code for curved space-times. We employ Google’s JAX framework for accelerated automatic differentiation, which can efficiently compute Christoffel symbols directly from the metric, allowing the user to easily and quickly simulate photon trajectories through non-Kerr metrics. JAX also enables Mahakala to run in parallel on both CPUs and GPUs and achieve speeds comparable to C-based codes. Mahakala natively uses the Cartesian Kerr-Schild coordinate system, which avoids numerical issues caused by the "pole" of spherical coordinates. We demonstrate Mahakala’s capabilities by simulating the 1.3 mm wavelength images (the wavelength of Event Horizon Telescope observations) of general relativistic magnetohydrodynamic simulations of low-accretion rate supermassive black holes. The modular nature of Mahakala allows us to easily quantify the relative contribution of different regions of the flow to image features. We show that most of the emission seen in 1.3 mm images originates close to the black hole. We also quantify the relative contribution of the disk, forward jet, and counter jet to 1.3 mm images. Copyright © 2023, The Authors. All rights reserved.

关键词： Python

Drive-Based Motivation for Coordination of Limit Cycle Behaviors

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Drive-Based Motivation for Coordination of Limit Cycle Behav...

IEEE Annual Conference on Decision and Control

作者： Craig Thompson Paul Reverdy Graduate Program in Applied Mathematics University of Arizona Tucson AZ USA

ISBN: (数字)9781728113982

ISBN: (纸本)9781728113999

Constructing autonomous systems capable of high-level behaviors often involves reducing these behaviors to a collection of low-level tasks. This requires developing a method for switching among possible tasks, for example using a hybrid automaton. Recent work has developed an alternative approach using continuous dynamical systems that have an internal drive state to select the desired task. In one particular result, authors considered a scenario where individual behaviors were encoded in control vector fields with unique, globally stable equilibria. A further level of complexity arises when one seeks to create a system that switches between tasks encoded as globally attracting sets with recurrent behaviors, rather than as point attractors. This work outlines the problem using the recently-developed drive-based dynamical framework. First we generalize the formulation of tasks as one part attracting set and one part recurrent behavior on said attracting set. Then as a proof-of-concept we demonstrate the existence of an attracting set consisting of orbits that repeatedly flow between two canonical limit cycles (e.g., Hopf oscillators).

关键词： Task analysis Limit-cycles Navigation Switches Automata

An inter-laboratory study of DNA-based identity,parentage and species testing in animal forensic genetics

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Forensic Sciences Research 2022年第4期7卷 708-713页

作者： Sreetharan Kanthaswamy Torsten Brendel Luis Cancela Denise A.Andrade de Oliveira Bertram Brenig Carmen Cons Julian A.Crespi Markéta Dajbychová Andreas Feldl Tomohito Itoh Vincenzo Landi Amparo Martinez Malgorzata Natonek-Wisniewska Robert F.Oldt Anna Radko Oscar Ramírez Clementina Rodellar Manuel Ruiz-Girón David Schikorski María Elena Turba Guillermo Giovambatista School of Mathematics and Natural Sciences Arizona State University(ASU)at the West CampusGlendaleAZUSA California National Primate Research Center University of CaliforniaDavisCAUSA Evolutionary Biology Graduate Program School of Life SciencesArizona State UniversityTempeAZUSA Eurofins Genomics Europe Applied Genomics GmbH EbersbergGermany IDENTITAS MontevideoUruguay Laboratório de Genética Escola de Veterinária da UFMGBelo HorizonteBrazil Institute of Veterinary Medicine University of GoettingenGoettingenGermany Facultad de Veterinaria Laboratorio de Genética Bioquímica(LAGENBIO)Instituto Agroalimentario de Aragón-IA2(Universidad de Zaragoza-CITA)ZaragozaSpain Facultad de Ciencias Veterinarias UNLP IGEVET-Instituto de Genética Veterinaria(UNLP-CONICET LAPLATA)La PlataArgentina Genomia s.r.o. PlzeňCzech Republic Maebashi Institute of Animal Science Livestock Improvement Association of Japan(LIAJ)MaebashiJapan Department of Veterinary Medicine Animal Breeding and GeneticsUniversity of Bari“Aldo Moro”ValenzanoItaly Department of Genetics Faculty of Veterinary SciencesUniversity of CórdobaCórdobaSpain Department of Animal Molecular Biology National Research Institute of Animal ProductionBalicePoland Vetgenomics SL BarcelonaSpain Laboratorio de Biología Molecular y Genómica Hispalis Biolab S.L.U.SevilleSpain Laboratoire LABOFARM-GENINDEXE LOUDEACCedexFrance Genefast SRL ForlìItaly

The probative value of animal forensic genetic evidence relies on laboratory accuracy and ***-laboratory comparisons allow laboratories to evaluate their performance on specific tests and analyses and to continue to monitor their *** International Society for Animal Genetics(ISAG)administered animal forensic comparison tests(AFCTs)in 2016 and 2018 to assess the limitations and capabilities of laboratories offering forensic identification,parentage and species determination *** AFCTs revealed that analyses of low DNA template concentrations(≤300 pg/μL)constitute a significant challenge that has prevented many laboratories from reporting correct identification and parentage ***,a lack of familiarity with species testing protocols,interpretation guidelines and representative databases prevented over a quarter of the participating laboratories from submitting correct species determination *** laboratories showed improvement in their genotyping accuracy over ***,the use of forensically validated standards,such as a standard forensic short tandem repeat(STR)kit,preferably with an allelic ladder,and stricter guidelines for STR typing,may have prevented some common issues from occurring,such as genotyping inaccuracies,missing data,elevated stutter products and loading *** AFCTs underscore the importance of conducting routine forensic comparison tests to allow laboratories to compare results from each *** should keep improving their scientific and technical capabilities and continuously evaluate their personnel’s proficiency in critical techniques such as low copy number(LCN)analysis and species *** this is the first time that the ISAG has conducted comparison tests for forensic testing,findings from these AFCTs may serve as the foundation for continuous improvements of the overall quality of animal forensic genetic testing.

关键词： Forensic sciences forensic genetics comparison test forensic DNA analysis individual identification parentage test species test

Meta-learning initializations for image segmentation

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arXiv 2019年

作者： Hendryx, Sean M. Leach, Andrew B. Hein, Paul D. Morrison, Clayton T. School of Information University of Arizona United States Program in Applied Mathematics University of Arizona United States

While meta-learning approaches that utilize neural network representations have made progress in few-shot image classification, reinforcement learning, and, more recently, image semantic segmentation, the training algorithms and model architectures have become increasingly specialized to the few-shot domain. A natural question that arises is how to develop learning systems that scale from few-shot to many-shot settings while yielding competitive performance in both. One scalable potential approach that does not require ensembling many models nor the computational costs of relation networks, is to meta-learn an initialization. In this work, we study first-order meta-learning of initializations for deep neural networks that must produce dense, structured predictions given an arbitrary amount of training data for a new task. Our primary contributions include (1), an extension and experimental analysis of first-order model agnostic meta-learning algorithms (including FOMAML and Reptile) to image segmentation, (2) a novel neural network architecture built for parameter efficiency and fast learning which we call EfficientLab, (3) a formalization of the generalization error of meta-learning algorithms, which we leverage to decrease error on unseen tasks, and (4) a small benchmark dataset, FP-k, for the empirical study of how meta-learning systems perform in both few- and many-shot settings. We show that meta-learned initializations for image segmentation provide value for both canonical few-shot learning problems and larger datasets, outperforming ImageNet-trained initializations for up to 400 densely labeled examples. We find that our network, with an empirically estimated optimal update procedure, yields state of the art results on the FSS-1000 dataset while only requiring one forward pass through a single model at evaluation time. Copyright © 2019, The Authors. All rights reserved.

关键词： Semantic Segmentation

Brightness asymmetry of black hole images as a probe of observer inclination

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arXiv 2021年

作者： Medeiros, Lia Chan, Chi-Kwan Narayan, Ramesh Özel, Feryal Psaltis, Dimitrios School of Natural Sciences Institute for Advanced Study 1 Einstein Drive PrincetonNJ08540 United States Steward Observatory and Department of Astronomy University of Arizona 933 N. Cherry Ave. TucsonAZ85721 United States Data Science Institute University of Arizona 1230 N. Cherry Ave. TucsonAZ85721 United States Program in Applied Mathematics University of Arizona 617 N. Santa Rita TucsonAZ85721 United States Center for Astrophysics | Harvard & Smithsonian 60 Garden Street CambridgeMA02138 United States

The Event Horizon Telescope recently captured images of the supermassive black hole in the center of the M87 galaxy, which show a ring-like emission structure with the South side only slightly brighter than the North side. This relatively weak asymmetry in the brightness profile along the ring has been interpreted as a consequence of the low inclination of the observer (around 17◦ for M87), which suppresses the Doppler beaming and boosting effects that might otherwise be expected due to the nearly relativistic velocities of the orbiting plasma. In this work, we use a large suite of general relativistic magnetohydrodynamic simulations to reassess the validity of this argument. By constructing explicit counter examples, we show that low-inclination is a sufficient but not necessary condition for images to have low brightness asymmetry. Accretion flow models with high accumulated magnetic flux close to the black hole horizon (the so-called magnetically arrested disks) and low black-hole spins have angular velocities that are substantially smaller than the orbital velocities of test particles at the same location. As a result, such models can produce images with low brightness asymmetry even when viewed edge on. Copyright © 2021, The Authors. All rights reserved.

关键词： Luminance

Gamma-ray Bursts as Distance Indicators by a Statistical Learning Approach

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arXiv 2024年

作者： Dainotti, Maria Giovanna Narendra, Aditya Pollo, Agnieszka Petrosian, Vahé Bogdan, Malgorzata Iwasaki, Kazunari Prochaska, Jason Xavier Rinaldi, Enrico Zhou, David National Astronomical Observatory of Japan Mitaka Tokyo181-8588 Japan The Graduate University for Advanced Studies SOKENDAI Kanagawa240-0193 Japan Space Science Institute BoulderCO80301 United States Doctoral School of Exact and Natural Sciences Jagiellonian University Krakow Poland Astronomical Observatory of Jagiellonian University Krakow Poland Warsaw Poland Department of Physics Stanford University 382 Via Pueblo Mall StanfordCA94305-4060 United States Kavli Institute for Particle Astrophysics and Cosmology Stanford University United States Department of Applied Physics Stanford University United States Department of Mathematics University of Wroclaw 50-384 Poland Department of Statistics Lund University LundSE-221 00 Sweden Center for Computational Astrophysics National Astronomical Observatory of Japan 2 Chome-21-1 Osawa Mitaka Tokyo181-8588 Japan University of California Santa Cruz 1156 High Street Santa CruzCA95064 United States Program RIKEN Saitama Wakoshi 351-0198 Japan Arizona State University 1151 S Forest Ave TempeAZ85281 United States

Gamma-ray bursts (GRBs) can be probes of the early universe, but currently, only 26% of GRBs observed by the Neil Gehrels Swift Observatory GRBs have known redshifts (z) due to observational limitations. To address this, we estimated the GRB redshift (distance) via a supervised statistical learning model that uses optical afterglow observed by Swift and ground-based telescopes. The inferred redshifts are strongly correlated (a Pearson coefficient of 0.93) with the observed redshifts, thus proving the reliability of this method. The inferred and observed redshifts allow us to estimate the number of GRBs occurring at a given redshift (GRB rate) to be 8.47-9yr−1Gpc−1 for 1.9 © 2024, CC BY.

关键词： Stars

Climate, food and humans predict communities of mammals in the United States

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Diversity and Distributions 2024年第9期30卷 e13900-e13900页

作者： Kays, Roland Snider, Matthew H. Hess, George Cove, Michael V. Jensen, Alex Shamon, Hila McShea, William J. Rooney, Brigit Allen, Maximilian L. Pekins, Charles E. Wilmers, Christopher C. Pendergast, Mary E. Green, Austin M. Suraci, Justin Leslie, Matthew S. Nasrallah, Sophie Farkas, Dan Jordan, Mark Grigione, Melissa LaScaleia, Michael C. Davis, Miranda L. Hansen, Chris Millspaugh, Josh Lewis, Jesse S. Havrda, Michael Long, Robert Remine, Kathryn R. Jaspers, Kodi J. Lafferty, Diana J. R. Hubbard, Tru Studds, Colin E. Barthelmess, Erika L. Andy, Katherine Romero, Andrea Hawkins, Melissa T. R. Lombardi, Jason V. Sergeyev, Maksim Fisher-Reid, M. Caitlin Rentz, Michael S. Nagy, Christopher Davenport, Jon M. Rega-Brodsky, Christine C. Appel, Cara L. Lesmeister, Damon B. Giery, Sean T. Whittier, Christopher A. Alston, Jesse M. Sutherland, Chris Rota, Christopher Murphy, Thomas Lee, Thomas E. Mortelliti, Alessio Bergman, Dylan L. Compton, Justin A. Gerber, Brian D. Burr, Jess Rezendes, Kylie DeGregorio, Brett A. Wehr, Nathaniel H. Benson, John F. Jachowski, David S. Gray, Morgan Beyer, Dean E. Belant, Jerrold L. Horan, Robert V. Lonsinger, Robert C. Kuhn, Kellie M. Hasstedt, Steven C. M. Zimova, Marketa Moore, Sophie M. Herrera, Daniel J. Fritts, Sarah Edelman, Andrew J. Flaherty, Elizabeth A. Petroelje, Tyler R. Neiswenter, Sean A. Risch, Derek R. Iannarilli, Fabiola van der Merwe, Marius Maher, Sean P. Farris, Zach J. Webb, Stephen L. Mason, David S. Lashley, Marcus A. Wilson, Andrew M. Vanek, John P. Wehr, Samuel R. Conner, L. Mike Beasley, James C. Bontrager, Helen L. Baruzzi, Carolina Ellis-Felege, Susan N. Proctor, Mike D. Schipper, Jan Weiss, Katherine C. B. Darracq, Andrea K. Barr, Evan G. Alexander, Peter D. Şekercioğlu, Çağan H. Bogan, Daniel A. Schalk, Christopher M. Fantle-Lepczyk, Jean E. Lepczyk, Christopher A. LaPoint, Scott Whipple, Laura S. Rowe, Helen Ivy Mullen, Kayleigh Bird, Tori Zorn, Adam Brandt, LaRoy Lathrop, Richard G. McCain, Craig Crupi, Anthony P. Clark, James Parsons, Arielle Department of Forestry and Environmental Resources North Carolina State University Raleigh NC United States North Carolina Museum of Natural Sciences Raleigh NC United States Department of Forestry and Environmental Conservation Clemson University Clemson SC United States Smithsonian's National Zoo and Conservation Biology Institute Front Royal VA United States Illinois Natural History Survey Prairie Research Institute University of Illinois Champaign IL United States Fort Hood Natural Resources Management Branch United States Army Garrison Fort Hood TX United States Environmental Studies Department Center for Integrated Spatial Research University of California Santa Cruz Santa Cruz CA United States Science Research Initiative University of Utah Salt Lake City UT United States Sageland Collaborative Salt Lake City UT United States Conservation Science Partners Inc. Truckee CA United States National Climate Adaptation Science Center United States Geological Survey Reston VA United States Biology Department Swarthmore College Swarthmore PA United States Entomology Department Cornell University Ithaca NY United States Information Technology Department Pace University Pleasantville NY United States Seattle University Department of Biology Seattle WA United States Department of Biology Pace University Pleasantville NY United States Department of Ecology and Evolutionary Biology Storrs CT United States Wildlife Biology Program Department of Ecosystem and Conservation Sciences University of Montana Missoula MT United States Department of Forest and Environmental Biology SUNY-ESF Syracuse NY United States Arizona State University College of Integrative Sciences and Arts Mesa AZ United States University of Washington School of Environmental and Forest Sciences Seattle WA United States Woodland Park Zoo Seattle WA United States Department of Biology Wildlife Ecology and Conservation Science Lab Northern Michigan University Marquette M

Aim: The assembly of species into communities and ecoregions is the result of interacting factors that affect plant and animal distribution and abundance at biogeographic scales. Here, we empirically derive ecoregions for mammals to test whether human disturbance has become more important than climate and habitat resources in structuring communities. Location: Conterminous United States. Time Period: 2010–2021. Major Taxa Studied: Twenty-five species of mammals. Methods: We analysed data from 25 mammal species recorded by camera traps at 6645 locations across the conterminous United States in a joint modelling framework to estimate relative abundance of each species. We then used a clustering analysis to describe 8 broad and 16 narrow mammal communities. Results: Climate was the most important predictor of mammal abundance overall, while human population density and agriculture were less important, with mixed effects across species. Seed production by forests also predicted mammal abundance, especially hard-mast tree species. The mammal community maps are similar to those of plants, with an east–west split driven by different dominant species of deer and squirrels. Communities vary along gradients of temperature in the east and precipitation in the west. Most fine-scale mammal community boundaries aligned with established plant ecoregions and were distinguished by the presence of regional specialists or shifts in relative abundance of widespread species. Maps of potential ecosystem services provided by these communities suggest high herbivory in the Rocky Mountains and eastern forests, high invertebrate predation in the subtropical south and greater predation pressure on large vertebrates in the west. Main Conclusions: Our results highlight the importance of climate to modern mammals and suggest that climate change will have strong impacts on these communities. Our new empirical approach to recognizing ecoregions has potential to be applied to expanded communities o

关键词： climate macroecology mammal communities masting species distribution models

The EB-correlation in Resolved Polarized Images: Connections to Astrophysics of Black Holes

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arXiv 2023年

作者： Emami, Razieh Doeleman, Sheperd S. Wielgus, MacIek Chang, Dominic Chatterjee, Koushik Smith, Randall Liska, Matthew Steiner, James F. Ricarte, Angelo Narayan, Ramesh Tremblay, Grant Finkbeiner, Douglas Hernquist, Lars Chan, Chi-Kwan Blackburn, Lindy Prather, Ben S. Tiede, Paul Broderick, Avery E. Vogelsberger, Mark Alcock, Charles Roelofs, Freek Center for Astrophysics Harvard & Smithsonian 60 Garden Street CambridgeMA02138 United States Black Hole Initiative Harvard University 20 Garden Street CambridgeMA02138 United States Max-Planck-Institut für Radioastronomie Auf dem Hügel 69 BonnD-53121 Germany Steward Observatory Department of Astronomy University of Arizona 933 N. Cherry Ave. TucsonAZ85721 United States Data Science Institute University of Arizona 1230 N. Cherry Ave. TucsonAZ85721 United States Program in Applied Mathematics University of Arizona 617 N. Santa Rita TucsonAZ85721 United States CCS-2 Los Alamos National Laboratory P.O. Box 1663 Los AlamosNM87545 United States Perimeter Institute for Theoretical Physics 31 Caroline Street North WaterlooONN2L 2Y5 Canada Department of Physics and Astronomy University of Waterloo 200 University Avenue West WaterlooONN2L 3G1 Canada Department of Physics Kavli Institute for Astrophysics and Space Research Massachusetts Institute of Technology CambridgeMA02139 United States

We present an in-depth analysis of a newly proposed correlation function in visibility space, between the E and B modes of the linear polarization, hereafter the EB-correlation, for a set of time-averaged GRMHD simulations compared with the phase map from different semi-analytic models as well as the Event Horizon Telescope (EHT) 2017 data for M87∗source. We demonstrate that the phase map of the time-averaged EB-correlation contains novel information that might be linked to the BH spin, accretion state and the electron temperature. A detailed comparison with a semi-analytic approach with different azimuthal expansion modes shows that to recover the morphology of the real/imaginary part of the correlation function and its phase, we require higher orders of these azimuthal modes. To extract the phase features, we propose to use the Zernike polynomial reconstruction developing an empirical metric to break degeneracies between models with different BH spins that are qualitatively similar. We use a set of different geometrical ring models with various magnetic and velocity field morphologies and show that both the image space and visibility based EB-correlation morphologies in MAD simulations can be explained with simple fluid and magnetic field geometries as used in ring models. SANEs by contrast are harder to model, demonstrating that the simple fluid and magnetic field geometries of ring models are not sufficient to describe them owing to higher Faraday Rotation depths. A qualitative comparison with the EHT data demonstrates that some of the features in the phase of EB-correlation might be well explained by the current models for BH spins as well as electron temperatures, while others may require a larger theoretical surveys. © 2023, CC BY.

关键词： Polarization