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arXiv 2022年

作者： Myers, Natalie Donor, John Spoo, Taylor Frinchaboy, Peter M. Cunha, Katia Price-Whelan, Adrian M. Majewski, Steven R. Beaton, Rachael L. Zasowski, Gail O’Connell, Julia Ray, Amy E. Bizyaev, Dmitry Chiappini, Cristina García-Hernández, D.A. Geisler, Doug Jönsson, Henrik Lane, Richard R. Longa-Peña, Penélope Minchev, Ivan Minniti, Dante Nitschelm, Christian Roman-Lopes, A. Department of Physics and Astronomy Texas Christian University TCU Box 298840 Fort WorthTX76129 United States Observatório Nacional Rua General José Cristino 77 RJ Rio de Janeiro20921-400 Brazil Steward Observatory University of Arizona 933 North Cherry Avenue TucsonAZ85721-0065 United States Center for Computational Astrophysics Flatiron Institute 162 Fifth Avenue New YorkNY10010 United States Department of Astronomy University of Virginia CharlottesvilleVA22904-4325 United States Department of Astrophysical Sciences Princeton University 4 Ivy Lane PrincetonNJ08544 United States The Observatories of the Carnegie Institution for Science 813 Santa Barbara St. PasadenaCA91101 United States Department of Physics & Astronomy University of Utah 115 S. 1400 E. Salt Lake CityUT84112 United States Apache Point Observatory New Mexico State University P.O. Box 59 Sunspot NM88349-0059 United States Sternberg Astronomical Institute Moscow State University Moscow Russia An der Sternwarte 16 Potsdam14482 Germany Instituto de Astrofísica de Canarias Vía Láctea S/N Tenerife La Laguna38205 Spain Universidad de La Laguna Departamento de Astrofísica Tenerife La Laguna30206 Spain Departamento de Astronomía Universidad de Concepción Casilla 160-C Concepción Chile Instituto de Investigación Multidisciplinario en Ciencia y Tecnología Universidad de La Serena Avenida Raúl Bitrán S/N La Serena Chile Department of Astronomy Universidad La Serena La Serena Chile Materials Science and Applied Mathematics Malmö University MalmöSE-205 06 Sweden Centro de Investigación en Astronomía Universidad Bernardo O’Higgins Avenida Viel 1497 Santiago Chile Universidad de Antofagasta Avenida Angamos 601 Antofagasta1270300 Chile Departamento de Ciencias Fisicas Facultad de Ciencias Exactas Universidad Andres Bello Av. Fernandez Concha 700 Las Condes Santiago Chile Vatican Observatory Vatican City State V00120 Italy

The goal of the Open Cluster Chemical Abundances and Mapping (OCCAM) survey is to constrain key Galactic dynamic and chemical evolution parameters by the construction and analysis of a large, comprehensive, uniform data set of infrared spectra for stars in hundreds of open clusters. This sixth contribution from the OCCAM survey presents analysis of SDSS/APOGEE Data Release 17 (DR17) results for a sample of stars in 150 open clusters, 94 of which we designate to be "high quality" based on the appearance of their color-magnitude diagram. We find the APOGEE DR17-derived [Fe/H] values to be in good agreement with those from previous high resolution spectroscopic open cluster abundance studies. Using a subset of the high quality sample, the Galactic abundance gradients were measured for 16 chemical elements, including [Fe/H], for both Galactocentric radius (RGC) and guiding center radius (RGuide). We find an overall Galactic [Fe/H] vs RGC gradient of −0.073 ± 0.002 dex/kpc over the range of 6 GC Guide. Significant Galactic abundance gradients are also noted for O, Mg, S, Ca, Mn, Na, Al, K and Ce. Our large sample additionally allows us to explore the evolution of the gradients in four age bins for the remaining 15 elements. © 2022, CC BY.

关键词： Surveys

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Joint quantum-state and measurement tomography with incomplete measurements

arXiv

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arXiv 2018年

作者： Keith, Adam C. Baldwin, Charles H. Glancy, Scott Knill, E. Applied and Computational Mathematics Division National Institute of Standards and Technology BoulderCO80305 United States Department of Physics University of Colorado BoulderCO80309 United States Center for Theory of Quantum Matter University of Colorado BoulderCO80309 United States

Estimation of quantum states and measurements is crucial for the implementation of quantum information protocols. The standard method for each is quantum tomography. However, quantum tomography su ers from systematic errors caused by imperfect knowledge of the system. We present a procedure to simultaneously characterize quantum states and measurements that mitigates systematic errors by use of a single high-fidelity state preparation and a limited set of high-fidelity unitary operations. Such states and operations are typical of many state-of-the-art systems. For this situation we design a set of experiments and an optimization algorithm that alternates between maximizing the likelihood with respect to the states and measurements to produce estimates of each. In some cases, the procedure does not enable unique estimation of the states. For these cases, we show how one may identify a set of density matrices compatible with the measurements and use a semi-definite program to place bounds on the state's expectation values. We demonstrate the procedure on data from a simulated experiment with two trapped ions. Copyright © 2018, The Authors. All rights reserved.

关键词： Tomography

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Interpretation of gravity satellite data to delineate structural features connected to geothermal resources at Bur Ni Geureudong geothermal field

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IOP Conference Series: Earth and Environmental Science 2019年第1期364卷

作者： D R Putri M Nanda S Rizal R Idroes N Ismail Doctoral Program of Mathematics and Applied Science Universitas Syiah Kuala Banda Aceh 23111 Indonesia Marine Sciences Department Universitas Syiah Kuala Banda Aceh 23111 Indonesia Department of Chemistry Faculty of Mathematics and Natural Sciences Universitas Syiah Kuala Kopelma Darussalam Banda Aceh 23111 Indonesia Department of Pharmacy Faculty of Mathematics and Natural Sciences Universitas Syiah Kuala Kopelma Darussalam Banda Aceh 23111 Indonesia Department of Physics Faculty of Mathematics and Natural Science Universitas Syiah Kuala Banda Aceh 23111 Indonesia

The gravity method is broadly used in analyzing potential geothermal studies. The method can be used for determining potential areas, reservoir locations, and geological structure investigation. In this paper, satellite gravity data was applied for better understand the geological conditions connected with the geothermal system of Bur Ni Geureudong geothermal field, Bener Meriah District, Aceh, Indonesia. Open access Free Air anomaly data were provided by satellite geodesy information with 1 minute-grid. The data were reduced to obtain Bouguer anomaly distribution in the study area. Tilt derivative (TDR) technique was applied to Bouguer anomaly to enhance linear trends of geological structures. The aim of this analytical technique is able to clearly display faults correlated with geothermal manifestations around the Bur Ni Geureudong geothermal field. The complete Bouguer anomaly range of 20 mGal up to 170 mGal covers Bur Ni Geureudong volcano complex. A low Bouguer anomaly is located in all summits of volcanoes that are included in Bur Ni Geureudong Volcano Complex; those are summits of Bur Geureudong volcano, Bur Ni Telong Volcano, Pepanji Mountain, and Salah Nama Mountain. The low Bouguer anomaly is associated with the andesitic flow and volcanic ashes. The higher Bouguer Anomaly is reflected in high-density basement rock in the west of Geureudong Volcano. Tilt derivative (TDR) shows geological structures more detail, particularly, the tilt derivative (TDR) clearly detects two fault structures over the study area presented by a tilt value of zero. The results will be useful as basic information in exploration study of Bur Ni Geureudong geothermal field.

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Smoothing for signals with discontinuities using higher order Mumford-Shah models

arXiv

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arXiv 2018年

作者： Storath, Martin Kiefer, Lukas Weinmann, Andreas Universität Heidelberg Germany University of Applied Sciences Wörzburg-Schweinfurt Germany Mathematical Imaging Group Universität Heidelberg Germany Department of Mathematics and Natural Sciences Hochschule Darmstadt Germany Institute of Computational Biology Helmholtz Zentrum Mönchen Germany

Minimizing the Mumford-Shah functional is frequently used for smoothing signals or time series with discontinuities. A significant limitation of the standard Mumford-Shah model is that linear trends and in general polynomial trends in the data are not well preserved. This can be improved by building on splines of higher order which leads to higher order Mumford-Shah models. In this work, we study these models in the univariate situation: we discuss important differences to the first order Mumford-Shah model, and we obtain uniqueness results for their solutions. As a main contribution, we derive fast minimization algorithms for Mumford-Shah models of arbitrary orders. We show that the worst case complexity of all proposed schemes is quadratic in the length of the signal. Remarkably, they thus achieve the worst case complexity of the fastest solver for the piecewise constant Mumford-Shah model (which is the simplest model of the class). Further, we obtain stability results for the proposed algorithms. We complement these results with a numerical study. Our reference implementation processes signals with more than 10,000 elements in less than one second. Copyright © 2018, The Authors. All rights reserved.

关键词： Potts model

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GLOBAL-IN-TIME STRICHARTZ ESTIMATES AND CUBIC SCHRÖDINGER EQUATION IN A CONICAL SINGULAR SPACE

arXiv

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arXiv 2017年

作者： Zhang, Junyong Zheng, Jiqiang Department of Mathematics Beijing Institute of Technology Beijing100081 China Institute of Applied Physics and Computational Mathematics Beijing100088 China

In this paper, we study Strichartz estimates for the Schrödinger equation on a metric cone X, where X = C(Y) = (0, ∞)r × Y and the cross section Y is a (n − 1)-dimensional closed Riemannian manifold (Y, h). For the metric g on X given by g = dr2 + r2h, let ∆g be the positive Friedrichs extension Laplacian on X and V = V0r−2 where V0 ∈ C∞(Y) is a real function such that the operator P:= ∆h + V0 + (n − 2)2/4 is a strictly positive operator on L2(Y). We establish the full range of global-in-time Strichartz estimates without loss for the Schrödinger equation associated with the operator LV = ∆g + V0r−2 including the endpoint estimate both in homogeneous and inhomogeneous cases. A new finding reveals that the range of admissible pairs at Ĥ s-level is influenced by the smallest eigenvalue of the operator P . This additionally proves the conjecture in Wang [Ann. Inst. Fourier 2006] and generalizes the results of Ford [Comm. Math. Phys. 2010] and Baskin-Marzuola-Wunsch [Contemp. Math. 2014]. As an application, we show the well-posedness theory and scattering theory for the Schrödinger equation with a cubic nonlinearity on this setting which verifies a conjecture in Baskin-Marzuola-Wunsch [Contemp. Math. 2014].MSC Codes 58J47, 42B37, 35Q40, 47J35 Copyright © 2017, The Authors. All rights reserved.

关键词： Schrodinger equation

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Low-rank solution methods for stochastic eigenvalue problems

arXiv

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arXiv 2018年

作者： Elman, Howard C. Su, Tengfei Department of Computer Science Institute for Advanced Computer Studies University of Maryland College ParkMD20742 United States Applied Mathematics & Statistics Scientific Computation Program University of Maryland College ParkMD20742 United States

We study efficient solution methods for stochastic eigenvalue problems arising from discretization of self-adjoint partial differential equations with random data. With the stochastic Galerkin approach, the solutions are represented as generalized polynomial chaos expansions. A low-rank variant of the inverse subspace iteration algorithm is presented for computing one or several minimal eigenvalues and corresponding eigenvectors of parameter-dependent matrices. In the algorithm, the iterates are approximated by low-rank matrices, which leads to significant cost savings. The algorithm is tested on two benchmark problems, a stochastic diffusion problem with some poorly separated eigenvalues, and an operator derived from a discrete stochastic Stokes problem whose minimal eigenvalue is related to the inf-sup stability constant. Numerical experiments show that the low-rank algorithm produces accurate solutions compared to the Monte Carlo method, and it uses much less computational time than the original algorithm without low-rank approximation. Copyright © 2018, The Authors. All rights reserved.

关键词： Eigenvalues and eigenfunctions

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Monitoring of Uterus Electrical Activities using Electromyography in Stage I Induction Labor

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Journal of Physics: Conference Series 2019年第1期1179卷 012133-012133页

作者： Rhomadona, Shinta Wurdiana Melyana Nurul Widyawati Suryono, S Postgraduate Applied Science Midwifery program Poltekkes Kemenkes Semarang Indonesia Diploma III of Midwifery Stikes William Booth Surabaya Indonesia Lecturer Postgraduate Applied Science Midwifery program Poltekkes Kemenkes Semarang Indonesia Department of Physics Faculty of Science and Mathematics Diponegoro University Semarang Indonesia

Labor induction is one of the main contributors of serious complication among mothers and babies. Prolonged artificial uterus muscle contraction may result in uterus hyper stimulation. One method of prevention is using the abdomen palpation technique. However, its practice has so far been less effective, less accurate, time consuming, and somehow subjective, as it requires meticulousness of the examiner. The WHO recommends that laboring mothers using induction technique should continuously be monitored. Therefore, there is a need for a much more accurate measure using a monitoring instrument that is capable of recording contraction. The instrument is electromyography. This research analyzed uterus electrical activities in stage I labor induction. The method used was observing 10 respondents undergoing labor induction for their contraction, every 15 minutes for 10 minutes each using electromyography. Monitoring results were then analyzed for frequency, duration, interval, and action potential, and these were presented as a trend. Results show a trend of frequency, duration, interval, and action potential of uterus contraction in stage I labor, with successful induction showing increasing rhythm, while failed induction indicating constant rhythm. Mean frequency, duration, interval, and action potential is 5.30 time/10 minutes, 55.89 seconds, 4.12 minutes, and 1.64 V respectively. Meanwhile, the 3 mothers with failed induction have mean frequency of 1.64x/10 minute, mean contraction duration of 21.74 seconds, and mean interval of 7.40 minutes, and mean action potential of 1.18 V.

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An approximate series solution of the semiclassical Wigner equation

arXiv

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arXiv 2017年

作者： Giannopoulou, K.S. Makrakis, G.N. Department of Mathematical Sciences Norwegian University of Science and Technology Trondheim Norway Department of Mathematics & Applied Mathematics University of Crete Heraklion Crete Greece Institute of Applied and Computational Mathematics FORTH Heraklion Crete Greece

We propose a new approximate series solution of the semiclassical Wigner equation by uniformization of WKB approximations of the Schrödinger eigenfunctions. Copyright © 2017, The Authors. All rights reserved.

关键词： Eigenvalues and eigenfunctions

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Graphs with extremal connected forcing numbers

arXiv

引用

arXiv 2017年

作者： Brimkov, Boris Fast, Caleb C. Hicks, Illya V. Department of Computational & Applied Mathematics Rice University HoustonTX77005 United States

Zero forcing is an iterative graph coloring process where at each discrete time step, a colored vertex with a single uncolored neighbor forces that neighbor to become colored. The zero forcing number of a graph is the cardinality of the smallest set of initially colored vertices which forces the entire graph to eventually become colored. Connected forcing is a variant of zero forcing in which the initially colored set of vertices induces a connected subgraph;the analogous parameter of interest is the connected forcing number. In this paper, we characterize the graphs with connected forcing numbers 2 and n − 2. Our results extend existing characterizations of graphs with zero forcing numbers 2 and n − 2;we use combinatorial and graph theoretic techniques, in contrast to the linear algebraic approach used to obtain the latter. We also present several other structural results about the connected forcing sets of a *** Codes 05C15 Copyright © 2017, The Authors. All rights reserved.

关键词： Iterative methods

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Topological schemas of memory spaces

arXiv

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arXiv 2017年

作者： Babichev, Andrey Dabaghian, Yuri Department of Computational and Applied Mathematics Rice University HoustonTX77005 United States

Hippocampal cognitive map-a neuronal representation of the spatial environment-is broadly discussed in the computational neuroscience literature for decades. More recent studies point out that hippocampus plays a major role in producing yet another cognitive framework that incorporates not only spatial, but also nonspatial memories-the memory space. However, unlike cognitive maps, memory spaces have been barely studied from a theoretical perspective. Here we propose an approach for modeling hippocampal memory spaces as an epiphenomenon of neuronal spiking activity. First, we suggest that the memory space may be viewed as a finite topological space-a hypothesis that allows treating both spatial and nonspatial aspects of hippocampal function on equal footing. We then model the topological properties of the memory space to demonstrate that this concept naturally incorporates the notion of a cognitive map. Lastly, we suggest a formal description of the memory consolidation process and point out a connection between the proposed model of the memory spaces to the so-called Morris' schemas, which emerge as the most compact representation of the memory structure. Copyright © 2017, The Authors. All rights reserved.

关键词： Topology

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