cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
On the stretch factor of convex polyhedra whose vertices are (almost) on a sphere
Creators: name: Smid, Michiel
name: Bose, Prosenjit
name: Carmi, Paz
name: Damian, Mirela
name: De Carufel, Jean-Lou
name: Hill, Darryl
name: Maheshwari, Anil
name: Liu, Yuyang
Publisher: name: Journal of Computational Geometry
Year: 2016

description: Let $P$ be a convex polyhedron in $\mathbb{R}^3$. The skeleton of $P$ is the graph whose vertices and edges are the vertices and edges of $P$, respectively. We prove that, if these vertices are on the unit-sphere, the skeleton is a $(0.999 \cdot \pi)$-spanner. If the vertices are very close to this sphere, then the skeleton is not necessarily a spanner. For the case when the boundary of $P$ is between two concentric spheres of radii $1$ and $R>1$, and the angles in all faces are at least $\theta$, we prove that the skeleton is a $t$-spanner, where $t$ depends only on $R$ and $\theta$. One of the ingredients in the proof is a tight upper bound on the geometric dilation of a convex cycle that is contained in an annulus.
description: Journal of Computational Geometry, Vol. 7 No. 1 (2016)
Recognizing shrinkable complexes is NP-complete
Creators: name: Attali, Dominique
name: Devillers, Olivier
name: Glisse, Marc
name: Lazard, Sylvain
Publisher: name: Journal of Computational Geometry
Year: 2016

description: We say that a simplicial complex is "shrinkable" if there exists a sequence of admissible edge contractions that reduces the complex to a single vertex. We prove that it is NP-complete to decide whether a (two-dimensional) simplicial complex is shrinkable. Along the way, we describe examples of contractible complexes that are not shrinkable.
description: Journal of Computational Geometry, Vol. 7 No. 1 (2016)
Near-linear time medial axis approximation of smooth curves in $\mathbb{R}^3$
Creators: name: Scheffer, Christian
Publisher: name: Journal of Computational Geometry
Year: 2016

description: We present the first algorithm to approximate the medial axis $M_{\gamma}$ of a smooth, closed curve $\gamma \subset \mathbb{R}^3$ in near-linear time. Our algorithm works on a sufficiently dense \eps-sample and comes with a convergence guarantee for the non-discrete, but continuous approximation object. As our approach also works correctly for a set of curves, we discuss the following application of the medial axis: The medial axis of two curves $\gamma_1$ and $\gamma_2$ can be applied to compute piecewise-linear simplifications of $\gamma_1$ and $\gamma_2$. In particular, a controllable tradeoff between the degree of simplification and the degree of falsification of the summed Fr\'{e}chet distance between $\gamma_1$ and $\gamma_2$ is obtained. Finally, we show that for simplifying $\gamma_1$ and $\gamma_2$, our approximation, instead of $M_{\gamma}$, can be applied while guaranteeing the same result.
description: Journal of Computational Geometry, Vol. 7 No. 1 (2016)
Viscous decretion discs around rapidly rotating stars
Creators: name: Lee, Umin
Publisher: name: arXiv
Year: 2013
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We discuss steady viscous Keplerian decretion discs around rapidly rotating stars. We assume that low frequency modes, which may be excited by the opacity bump mechanism, convective motion in the core, or tidal force if the star is in a binary system, can transport an enough amount of angular momentum to the region close to the stellar surface. Under this assumption, we construct a star-disc system, in which there forms a viscous decretion disc around a rapidly rotating star because of the angular momentum supply. We find a series of solutions of steady viscous decretion discs around a rapidly rotating star that extend to $R_{\rm disc}\gtsim~10R_*$ with $R_*$ being the equatorial radius of the star, depending on the amount of angular momentum supply.
description: 13 pages, 6 figures, accepted for publication in PASJ
The worst visibility walk in a random Delaunay triangulation is $O(\sqrt{n})$
Creators: name: Devillers, Olivier
name: Hemsley, Ross
Publisher: name: Journal of Computational Geometry
Year: 2016

description: We show that the memoryless routing algorithms Greedy Walk, Compass Walk, and all variants of visibility walk based on orientation predicates are asymptotically optimal in the average case on the Delaunay triangulation. More specifically, we consider the Delaunay triangulation of an unbounded Poisson point process of unit rate and demonstrate that, for any pair of vertices $(s,t)$ inside $[0,n]^2$, the ratio between the longest and shortest visibility walks between $s$ and $t$ is bounded by a constant with probability converging to one (as long as the vertices are sufficiently far apart). As a corollary, it follows that the worst-case path has $O(\sqrt{n}\,)$ steps in the limiting case, under the same conditions. Our results have applications in routing in mobile networks and also settle a long-standing conjecture in point location using walking algorithms. Our proofs use techniques from percolation theory and stochastic geometry.
description: Journal of Computational Geometry, Vol. 7 No. 1 (2016)
Flat norm decomposition of integral currents
Creators: name: Ibrahim, Sharif
name: Krishnamoorthy, Bala
name: Vixie, Kevin
Publisher: name: Journal of Computational Geometry
Year: 2016

description: Currents represent generalized surfaces studied in geometric measure theory. They range from relatively tame integral currents representing oriented compact manifolds with boundary and integer multiplicities, to arbitrary elements of the dual space of differential forms. The flat norm provides a natural distance in the space of currents, and works by decomposing a $d$-dimensional current into $d$- and (the boundary of) $(d+1)$-dimensional pieces in an optimal way. Given an integral current, can we expect its at norm decomposition to be integral as well? This is not known in general, except in the case of $d$-currents that are boundaries of $(d+1)$-currents in $\mathbb{R}^{d+1}$ (following results from a corresponding problem on the $L^1$ total variation ($L^1$TV) of functionals). On the other hand, for a discretized at norm on a finite simplicial complex, the analogous statement holds even when the inputs are not boundaries. This simplicial version relies on the total unimodularity of the boundary matrix of the simplicial complex; a result distinct from the $L^1$TV approach. We develop an analysis framework that extends the result in the simplicial setting to one for $d$-currents in $\mathbb{R}^{d+1}$, provided a suitable triangulation result holds. In $\mathbb{R}^2$, we use a triangulation result of Shewchuk (bounding both the size and location of small angles), and apply the framework to show that the discrete result implies the continuous result for $1$-currents in $\mathbb{R}^2$ .
description: Journal of Computational Geometry, Vol. 7 No. 1 (2016)
An algorithm for the Euclidean cell decomposition of a non-compact strictly convex projective surface
Creators: name: Tillmann, Stephan
name: Wong, Sampson
Publisher: name: Journal of Computational Geometry
Year: 2016

description: Cooper and Long generalised Epstein and Penner's Euclidean cell decomposition of cusped hyperbolic $n$–manifolds of finite volume to non-compact strictly convex projective $n$–manifolds of finite volume. We show that Weeks' algorithm to compute this decomposition for a hyperbolic surface generalises to strictly convex projective surfaces.
description: Journal of Computational Geometry, Vol. 7 No. 1 (2016)
title: Метод построения туристического маршрута среди достопримечательностей на основе контекстной информации
Creators: name: ., С.А. Михайлов – аспирант, СПб НИУ информационных технологий, механики и оптики; мл. науч. сотрудник, лаборатория интегрированных систем автоматизации, Санкт-Петербургский институт информатики и автоматизации РАН E-mail: sergei.mikhailov@iias.spb.su А.М. Кашевник – к.т.н., ст. науч. сотрудник, лаборатория интегрированных систем автоматизации, Санкт-Петербургский институт информатики и автоматизации РАН E-mail: alexey@iias.spb.su
Publisher: name: Издательство Радиотехника
Year: 2019

description: Постановка проблемы. Индустрия туризма активно развивается во всем мире в течение последних лет. По прогнозу все-мирной туристической организации при ООН UNWTO к 2030 г. общее число международных поездок будет достигать 1,8 млрд. Туристы в своих путешествиях все чаще используют персональные мобильные устройства и сеть Интернет для получения подходящих для них туристических маршрутов. Проблема построения маршрута с посещением наиболее подходящих туристу достопримечательностей за определенные временные рамки (Orienteering Problem with Time Windows) является актуальной и исследуемой на протяжении последних десятилетий.
Цель. Построить маршрут посещения достопримечательностей методом, учитывающим условия и предпочтения туриста. Для решения представленной проблемы в мире используются муравьиные/пчелиные алгоритмы, методы локального поиска, а также эволюционные алгоритмы. Однако зачастую при составлении маршрутов в качестве критериев полноценно не используется кон-текстная информация – учитывается только местоположение туриста и время работы достопримечательностей.
Результаты. Предложенный метод базируется на технологиях рекомендующих систем при подборе достопримечательностей и ориентирован на использование онтологического подхода совместно с методами управления контекстом при создании маршрута. Контекст в рамках данной работы разделяется на две части: пользовательскую, которая описывает ситуацию о туристе, и региональную, которая касается региона, в котором турист находится. Для решения обозначенной проблемы предложена адаптация метода локального поиска путем добавления мультикритериальности выбора достопримечательностей на основе контекстной информации.
Практическая значимость. Метод позволит строить туристический маршрут, соответствующий желаниям и потребностям туриста, что может привести к общему удовлетворению при использовании системы помощи туристу.
Exploring Storypark's design and use for documenting children's learning: A critical multimodal study of a digital documentation app
Creators: name: Athota, Jane
Publisher: name: Macquarie University
Year: 2023
Subjects: Other education not elsewhere classified

description: As the use of commercial digital documentation applications (apps) in early childhood education and care (ECEC) settings expands, there is a pressing need to understand whether and how they influence documentation practices. A small body of research has highlighted the benefits and challenges documentation apps present for ECEC services, which include enhanced communication between families and educators, but also increased educator workload. As previous research has paid minimal attention to the design and use of specific documentation apps, little is known about the affordances these technologies offer for communicating multimodally, through various modes and media such as writing, photos, video, and sound, and their potential to shape educators’ documentation practices. Adopting a critical multimodal approach to semiotic software, or software for making and exchanging meaning (Djonov & van Leeuwen, 2018), this study investigated the design and use of Storypark, a documentation app used in many ECEC services in Australia and internationally. To explore whether and how Storypark shapes educators’ documentation practices, this project incorporated a qualitative analysis of the app’s interface and promotional materials, a content analysis of the modes and media employed in 132 stories of children’s learning created with Storypark in two Australian ECEC centres, and a thematic analysis of individual, semi-structured, visual-elicitation interviews conducted with four educators who had created some of these stories about their use of Storypark. Findings reveal that the app’s design offers resources that could help address key goals and challenges in pedagogic documentation, such as making visible and reflecting on children’s learning and perspectives. The app also exerts considerable influence over educators’ documentation practices, alongside factors such as centre policies and educators’ knowledge and time-constraints. The study contributes to knowledge about digital documentation in ECEC and semiotic software, and has implications for educators, ECE service managers, policy makers and software developers.
The FAST Galactic Plane Pulsar Snapshot survey: VIII. 116 binary pulsars
Creators: name: Wang, P. F.
name: Han, J. L.
name: Yang, Z. L.
name: Wang, T.
name: Wang, C.
name: Su, W. Q.
name: Xu, J.
name: Zhou, D. J.
name: Yan, Yi
name: Jing, W. C.
name: Cai, N. N.
name: Yuan, J. P.
name: Xu, R. X.
name: Wang, H. G.
name: You, X. P.
Publisher: name: arXiv
Year: 2024
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Finding pulsars in binaries are important for measurements of the masses of neutron stars, for tests of gravity theories, and for studies of star evolution. We are carrying out the Galactic Plane Pulsar Snapshot survey (GPPS) by using the the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Here we present the Keplerian parameters for 116 newly discovered pulsars in the FAST GPPS survey, and obtain timing solutions for 29 pulsars. Companions of these pulsars are He white dwarfs, CO/ONe white dwarfs, neutron stars, main sequence stars and ultra light objects or even planets. Our observations uncover eclipses of 8 binary systems. The optical counterpart for the companion of PSR J1908+1036 is identified. The Post-Keplerian parameter $\dotω$ for the double neutron star systems PSR J0528+3529 and J1844-0128 have been measured, with which the total masses of the binary systems are determined.
description: 19+16 pages, 11+3 figures, 7+1 tables, published in RAA
The MEG detector for $μ+\to e+γ$ decay search
Creators: name: Adam, J.
name: Bai, X.
name: Baldini, A. M.
name: Baracchini, E.
name: Bemporad, C.
name: Boca, G.
name: Cattaneo, P. W.
name: Cavoto, G.
name: Cei, F.
name: Cerri, C.
name: Corbo, M.
name: Curalli, N.
name: De Bari, A.
name: De Gerone, M.
name: Del Frate, L.
name: Doke, S.
name: Dussoni, S.
name: Egger, J.
name: Fratini, K.
name: Fujii, Y.
name: Galli, L.
name: Galeotti, S.
name: Gallucci, G.
name: Gatti, F.
name: Golden, B.
name: Grassi, M.
name: Graziosi, A.
name: Grigoriev, D. N.
name: Haruyama, T.
name: Hisamatsu, M. Hildebrandt Y.
name: Ignatov, F.
name: Iwamoto, T.
name: Kaneko, D.
name: Kasami, K.
name: Kettle, P. -R.
name: Khazin, B. I.
name: Korenchenko, O. Kiselev A.
name: Kravchuk, N.
name: Lim, G.
name: Maki, A.
name: Mihara, S.
name: Molzon, W.
name: Mori, T.
name: Morsani, F.
name: Mzavia, D.
name: Nardò, R.
name: Natori, H.
name: Nicolò, D.
name: Nishiguchi, H.
name: Ootani, Y. Nishimura W.
name: Ozone, K.
name: Panareo, M.
name: Papa, A.
name: Pazzi, R.
name: Piredda, G.
name: Popov, A.
name: Raffaelli, F.
name: Renga, F.
name: Ripiccini, E.
name: Ritt, S.
name: Rossella, M.
name: Sawada, R.
name: Schneebeli, M.
name: Sergiampietri, F.
name: Signorelli, G.
name: Suzuki, S.
name: Tenchini, F.
name: Topchyan, C.
name: Uchiyama, Y.
name: Voena, R. Valle C.
name: Xiao, F.
name: Yamada, S.
name: Yamamoto, S.
name: Yamashita, S.
name: Yudin, Yu. V.
name: Zanello, D.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: The MEG (Mu to Electron Gamma) experiment has been running at the Paul Scherrer Institut (PSI), Switzerland since 2008 to search for the decay \meg\ by using one of the most intense continuous $μ^+$ beams in the world. This paper presents the MEG components: the positron spectrometer, including a thin target, a superconducting magnet, a set of drift chambers for measuring the muon decay vertex and the positron momentum, a timing counter for measuring the positron time, and a liquid xenon detector for measuring the photon energy, position and time. The trigger system, the read-out electronics and the data acquisition system are also presented in detail. The paper is completed with a description of the equipment and techniques developed for the calibration in time and energy and the simulation of the whole apparatus.
description: 59 pages, 90 figures
title: Комбинированный SLAM-метод навигации внутри помещений на основе гауссовского процесса скрытой переменной
Creators: name: ., М.С. Щекотов – науч. сотрудник, Санкт-Петербургский институт информатики и автоматизации РАН E-mail: shekotov@iias.spb.su
Publisher: name: Издательство Радиотехника
Year: 2019

description: Постановка проблемы. Одной из проблем, связанных с применением методов определения местоположения пользователей мобильных устройств внутри помещений на основе радиосигналов Wi-Fi, является трудоемкая процедура настройки и размещения оборудования, которая включает в себя построение карты помещения, создание карты радиосигналов или калибровку модели распространения радиосигнала. В решении данной проблемы планируется использовать SLAM-метод на основе гауссовского процесса скрытой переменной, включающего в себя фазу формирования обучающей выборки, а также фазу одновременной навигации и составления карты.
Цель. Разработать комбинированный SLAM-метод навигации на основе гауссовского процесса скрытой переменной, который обеспечивает навигацию пользователя внутри помещения и одновременно с этим позволяет строить карты радиосигналов Wi-Fi. Метод включает в себя требования по корреляции значений уровня сигнала ближайших точек локализации пользователя, для выполнения которых настраиваются параметры корреляционной функции на основе обучающей выборки, которая формируется с помощью крауд-вычислений.
Результаты. Предложен комбинированный SLAM-метод навигации на основе гауссовского процесса скрытой величины для коллаборативного построения карт радиосигналов Wi-Fi. Предложенный метод основывается на решении задачи регрессии методами машинного обучения для формирования обучающей выборки, а также на решении задачи уменьшения размерности для одновременной навигации и построения карты. В качестве обучающей выборки используются показания внутренних сенсоров смартфона (шаги и углы поворота) и уровни радиосигналов Wi-Fi, полученные с помощью крауд-вычислений. Полученная обучающая выборка служит для определения параметров корреляционной функции, задающей корреляцию между точками локализации пользователя. Также предложена процедура геймификация процесса определения входа пользователя в помещение и поиска им точек доступа Wi-Fi.
Практическая значимость. Предложенный метод позволяет не осуществлять предварительные трудоемкие процедуры построения карт помещений и радиосигналов.
title: Модели динамического конфигурирования смарт-контрактов пакетов услуг
Creators: name: ., Т.В. Левашова – к.т.н., ст. науч. сотрудник, лаборатория интегрированных систем автоматизации, Санкт-Петербургский институт информатики и автоматизации РАН E-mail: tatiana.levashova@iias.spb.su М.П. Пашкин – к.т.н., ст. науч. сотрудник, лаборатория интегрированных систем автоматизации, Санкт-Петербургский институт информатики и автоматизации РАН E-mail: michaelpashkin@mail.ru
Publisher: name: Издательство Радиотехника
Year: 2019

description: Постановка проблемы. Представленные в работе исследования направлены на решение проблемы разработки основ построения рекомендующих систем для динамического конфигурирования продуктов на основе моделей их онтолого-ориентированного представления и контекстно-ориентированного динамического конфигурирования, а также результатов профилирования потребителей (пользователей).
Цель. Разработать модели динамического конфигурирования смарт-контрактов пакетов услуг.
Результаты. Построены концептуальная и сценарная модели динамического конфигурирования смарт-контрактов пакетов услуг. Модели реализуют идею формирования пакета услуг из разрозненных услуг таким образом, чтобы в различных ситуациях пользователю предоставлялись услуги, соответствующие его потребностям именно в этих ситуациях. Для регулирования условий предоставления услуг используются смарт-контракты. Конфигурация смарт-контракта определяется предоставляемыми в конкретной ситуации услугами. За формирование пакета услуг и конфигурирование смарт-контрактов отвечает рекомендующая система. Пакет услуг формируется при приобретении пользователем продукта на основании онтологии продукта и профиля пользователя. В пакет услуг включаются только те услуги, которые в соответствии с профилем пользователя попадают в область его интересов. Для пакета услуг создается абстрактная конфигурация смарт-контракта. При нахождении пользователя в ситуации, предполагающей использование услуг из пакета, определяются его текущие потребности, осуществляется переконфигурирование смарт-контракта и контракт запускается на исполнение. В результате пользователю автоматически предоставляются только те услуги, которые соответствуют его потребностям в текущей ситуации, а также автоматически проверяются условия предоставления этих услуг. Разработанные модели предполагают применение методов онтологического моделирования продукта и пользователя, объединения онтологических моделей, динамического конфигурирования, а также концепций рекомендующих систем и смарт-контрактов.
Практическая значимость. Разработанные модели возможно использовать при персонализированном конфигурировании продуктов в различных сферах бизнеса для повышения качества обслуживания потребителя и его заинтересованности в приобретении продуктов.
Scattering amplitude and pomeron loops in perturbative QCD at large $N_c$
Creators: name: Braun, M. A.
name: Tarasov, A. N.
Publisher: name: arXiv
Year: 2013
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: The amplitude for the collision of two hadrons with the lowest order pomeron loop is calculated. Numerical calculations show that the loop contribution to the amplitude begins to dominate the single pomeron exchange at rapidities 8-10. Full dependence of the triple-pomeron vertex on intermediate conformal weights is taken into account.
description: 10 pages, 2 figures
Weighted geometric set multi-cover via quasi-uniform sampling
Creators: name: Bansal, Nikhil
name: Pruhs, Kirk
Publisher: name: Journal of Computational Geometry
Year: 2016

description: We give a randomized polynomial time algorithm with approximation ratio $O(\log \phi(n))$ for weighted set multi-cover instances with a shallow cell complexity of at most $f(z,k) =z\phi(z) k^{O(1)}$. Up to constant factors, this matches a recent result of Chan, Grant, Konemann and Sharpe for the set cover case, i.e. when all the covering requirements are 1. One consequence of this is an $O(1)$-approximation for geometric weighted set multi-cover problems when the geometric objects have linear union complexity; for example when the objects are disks, unit cubes or halfspaces in $\mathbb{R}^3$. Another consequence is to show that the real diculty of many natural capacitated set covering problems lies with solving the associated priority cover problem only, and not with the associated multi-cover problem.
description: Journal of Computational Geometry, Vol. 7 No. 1 (2016)
Recursively-regular subdivisions and applications
Creators: name: Jaume, Rafel
name: Rote, Günter
Publisher: name: Journal of Computational Geometry
Year: 2016

description: We generalize regular subdivisions (polyhedral complexes resulting from the projection of the lower faces of a polyhedron) introducing the class of recursively-regular subdivisions. Informally speaking, a recursively-regular subdivision is a subdivision that can be obtained by splitting some faces of a regular subdivision by other regular subdivisions (and continue recursively). We also define the finest regular coarsening and the regularity tree of a polyhedral complex. We prove that recursively-regular subdivisions are not necessarily connected by flips and that they are acyclic with respect to the in-front relation. We show that the finest regular coarsening of a subdivision can be efficiently computed, and that whether a subdivision is recursively regular can be efficiently decided. As an application, we also extend a theorem known since 1981 on illuminating space by cones and present connections of recursive regularity to tensegrity theory and graph-embedding problems.
description: Journal of Computational Geometry, Vol. 7 No. 1 (2016)
Democratizing global governance through the use of a joint legal/market accountability system: the bet of the World Bank and corporate social responsibility
Creators: name: Gellert, Raphael
Publisher: name: My University
Year: 2009
Subjects: accountability
corporate responsibility
global responsibility
World Bank
global governance

description: Second semester: University of Helsinki.
description: The idea of this Master's thesis was born from the observation that what is referred to as globalisation is deeply affecting the world we live in. Indeed, more and more transnational institutions are entrusted with (regulatory) powers that had always been thought of as solely belonging to States. However, they are far from being democratic. This thesis will focus on one of those institutions: the World Bank; with the aim of making it more accountable. Indeed, in accordance with the Global Administrative Law project, I argue that, as far as today, accountability is the form of democratic responsibility which is best adapted to the global paradigm. After having described how the World Bank interprets its mission of poverty alleviation, I shall proceed to an in-depth analysis of the concept of accountability. On that basis I will analyse the accountability mechanisms existing at the Bank, and conclude that they do not conform to the concept. Therefore, I will argue for a new accountability mechanism: a joint legal/market accountability system, through the use of Corporate Social Responsibility instruments, which will build upon the World Bank's mission. To that end, I will demonstrate that the field of development can be framed as a market, and that the World Bank has a dual nature (Corporation and Public Institution). Finally, I will outline in what ways the proposed solution can work.
Rigid origami vertices: conditions and forcing sets
Creators: name: Abel, Zachary
name: Cantarella, Jason
name: Demaine, Erik D.
name: Eppstein, David
name: Hull, Thomas C.
name: Ku, Jason S.
name: Lang, Robert J.
name: Tachi, Tomohiro
Publisher: name: Journal of Computational Geometry
Year: 2016

description: We develop an intrinsic necessary and sufficient condition for single-vertex origami crease patterns to be able to fold rigidly. We classify such patterns in the case where the creases are pre-assigned to be mountains and valleys as well as in the unassigned case. We also illustrate the utility of this result by applying it to the new concept of minimal forcing sets for rigid origami models, which are the smallest collection of creases that, when folded, will force all the other creases to fold in a prescribed way.
description: Journal of Computational Geometry, Vol. 7 No. 1 (2016)
Emergence of time in power-counting renormalizable Riemannian theory of gravity
Creators: name: Mukohyama, Shinji
Publisher: name: arXiv
Year: 2013
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We suggest a new scenario of gravitation in which gravity at the fundamental level is described by a Riemannian (i.e. locally Euclidean) theory without the notion of time. The Lorentzian metric structure and the notion of time emerge as effective properties at long distances. On the other hand, at short distances, higher derivative terms compatible with the Riemannian diffeomorphism become important and the system is described by a power-counting renormalizable Riemannian theory.
description: 16 pages, no figure; version accepted for publication in PRD
A type A structure in Khovanov Homology
Creators: name: Roberts, Lawrence P.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Geometric Topology (math.GT)
subject: FOS: Mathematics

description: Inspired by bordered Floer homology, we describe a type A structure on a Khovanov homology for a tangle, which complements the type D structure in a previous paper. The type A structure is a differential module over a certain algebra. This can be paired with the type D structure to recover the Khovanov chain complex. The homotopy type of the type A structure is a tangle invariant, and homotopy equivalences of the type A structure result in chain homotopy equivalences on the Khovanov chain complex. We can use this to simplify computations and introduce a modular approach to the computation of Khovanov homologies. This approach adds to the literature even in the case of a connect sum, where the techniques here will allow an exact computation of Khovanov homology from the structures for two tangles coming from the summands. Several examples are included, showing in particular how we can compute the correct torsion summands for the Khovanov homology of the connect sum. A lengthy appendix is devoted to establishing the theory of these structures over a characterstic zero ring.
description: The main text is 38 pgs. There is a roughly 20 pg appendix verifying the sign conventions. The second version added a note recognizing the independent discovery of similar constructions by Cotton Seed. The third version includes another type of relation, required in the construction, and other modifications due to this relation. Minor improvements in exposition, and references
Cognitive Outcomes in Adolescents Treated with Electroconvulsive Therapy
Creators: name: Ghaziuddin, Neera
name: Dolan, Michael
name: Heinrich, Kimberley
name: Hodges, Elise
name: Almy, Brandon
name: Ghaziuddin, Mohammad
Publisher: name: My University
Year: 2023
Subjects: Neuromodulation
Depression/depressive disorder

description: This study identified that the cognitive function of adolescents treated with electroconvulsive therapy (ECT) did not signficantly differ from their pre-ECT cognive performance when baseline and function at approximately 2 months post-ECT was compared.
Polyhedral Gauss sums, and polytopes with symmetry
Creators: name: Malikiosis, Romanos Diogenes
name: Robins, Sinai
name: Zhang, Yichi
Publisher: name: Journal of Computational Geometry
Year: 2016

description: We define certain natural finite sums of $n$'th roots of unity, called $G_P(n)$, that are associated to each convex integer polytope $P$, and which generalize the classical $1$-dimensional Gauss sum $G(n)$ defined over $\mathbb Z/ {n \mathbb Z}$, to higher dimensional abelian groups and integer polytopes. We consider the finite Weyl group $\mathcal{W}$, generated by the reflections with respect to the coordinate hyperplanes, as well as all permutations of the coordinates; further, we let $\mathcal G$ be the group generated by $\mathcal{W}$ as well as all integer translations in $\mathbb Z^d$. We prove that if $P$ multi-tiles $\mathbb R^d$ under the action of $\mathcal G$, then we have the closed form $G_P(n) = \text{vol}(P) G(n)^d$. Conversely, we also prove that if $P$ is a lattice tetrahedron in $\mathbb R^3$, of volume $1/6$, such that $G_P(n) = \text{vol}(P) G(n)^d$, for $n \in \{ 1,2,3,4 \}$, then there is an element $g$ in $\mathcal G$ such that $g(P)$ is the fundamental tetrahedron with vertices $(0,0,0)$, $(1, 0, 0)$, $(1,1,0)$, $(1,1,1)$.
description: Journal of Computational Geometry, Vol. 7 No. 1 (2016)
Molecular Line Emission from Multifluid Shock Waves. I. Numerical Methods and Benchmark Tests
Creators: name: Ciolek, Glenn E.
name: Roberge, Wayne G.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We describe a numerical scheme for studying time-dependent, multifluid, magnetohydrodynamic shock waves in weakly ionized interstellar clouds and cores. Shocks are modeled as propagating perpendicular to the magnetic field and consist of a neutral molecular fluid plus a fluid of ions and electrons. The scheme is based on operator splitting, wherein time integration of the governing equations is split into separate parts. In one part independent homogeneous Riemann problems for the two fluids are solved using Godunov's method. In the other equations containing the source terms for transfer of mass, momentum, and energy between the fluids are integrated using standard numerical techniques. We show that, for the frequent case where the thermal pressures of the ions and electrons are << magnetic pressure, the Riemann problems for the neutral and ion-electron fluids have a similar mathematical structure which facilitates numerical coding. Implementation of the scheme is discussed and several benchmark tests confirming its accuracy are presented, including (i) MHD wave packets ranging over orders of magnitude in length and time scales; (ii) early evolution of mulitfluid shocks caused by two colliding clouds; and (iii) a multifluid shock with mass transfer between the fluids by cosmic-ray ionization and ion-electron recombination, demonstrating the effect of ion mass loading on magnetic precursors of MHD shocks. An exact solution to a MHD Riemann problem forming the basis for an approximate numerical solver used in the homogeneous part of our scheme is presented, along with derivations of the analytic benchmark solutions and tests showing the convergence of the numerical algorithm.
description: To appear in The Astrophysical Journal. 70 pages including 14 figures. New update corrects some typos found when going over galley proofs
Hyperorthogonal well-folded Hilbert curves
Creators: name: Bos, Arie
name: Haverkort, Herman
Publisher: name: Journal of Computational Geometry
Year: 2016

description: R-trees can be used to store and query sets of point data in two or more dimensions. An easy way to construct and maintain R-trees for two-dimensional points, due to Kamel and Faloutsos, is to keep the points in the order in which they appear along the Hilbert curve. The R-tree will then store bounding boxes of points along contiguous sections of the curve, and the efficiency of the R-tree depends on the size of the bounding boxes---smaller is better. Since there are many different ways to generalize the Hilbert curve to higher dimensions, this raises the question which generalization results in the smallest bounding boxes. Familiar methods, such as the one by Butz, can result in curve sections whose bounding boxes are a factor $\Omega(2^{d/2})$ larger than the volume traversed by that section of the curve. Most of the volume bounded by such bounding boxes would not contain any data points. In this paper we present a new way of generalizing Hilbert's curve to higher dimensions, which results in much tighter bounding boxes: they have at most 4 times the volume of the part of the curve covered, independent of the number of dimensions. Moreover, we prove that a factor 4 is asymptotically optimal.
description: Journal of Computational Geometry, Vol. 7 No. 2 (2016): Special Issue of Selected Papers from SoCG 2015
Quantum motion and level quantization of a skyrmion in a pinning potential in chiral magnets
Creators: name: Lin, Shi-Zeng
name: Bulaevskii, Lev N.
Publisher: name: arXiv
Year: 2013
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Pattern Formation and Solitons (nlin.PS)
subject: FOS: Physical sciences

description: A new topological excitation called skyrmion has been observed experimentally in chiral magnets without spatial inversion symmetry. The dynamics of a skyrmion is equivalent to an electron moving in a strong magnetic field. As a skyrmion involves large number of spins, it is not clear whether there exist observable quantum effects. In this work, we study the quantum dynamics of a skyrmion in a pinning potential. Without a pinning potential, the skyrmion performs cyclotron motion due to the strong emergent magnetic field originating from the Berry phase of spins, and all skyrmions occupy the lowest Landau level. Their wave functions are strongly localized in a region with radius less than $1\ Å$ when no driving force is applied. Thus in most circumstances, the quantum effects of a skyrmion are weak. In the presence of a pinning potential, the lowest Landau level for skyrmions is split into quantized levels, characterized by the orbital moments. The transition between quantized levels can be observed experimentally by microwave absorption measurements in low temperature region. The quantum effects are more prominent for a skyrmion with a small size, which can be realized in magnets with a large Dzyaloshinskii-Moriya interaction.
description: 4.2 pages, 2 figures
Adjacency-preserving spatial treemaps
Creators: name: Buchin, Kevin
name: Eppstein, David
name: Löffler, Maarten
name: Nöllenburg, Martin
name: Silveira, Rodrigo
Publisher: name: Journal of Computational Geometry
Year: 2016

description: Rectangular layouts, subdivisions of an outer rectangle into smaller rectangles, have many applications in visualizing spatial information, for instance in rectangular cartograms in which the rectangles represent geographic or political regions. A spatial treemap is a rectangular layout with a hierarchical structure: the outer rectangle is subdivided into rectangles that are in turn subdivided into smaller rectangles. We describe algorithms for transforming a rectangular layout that does not have this hierarchical structure, together with a clustering of the rectangles of the layout, into a spatial treemap that respects the clustering and also respects to the extent possible the adjacencies of the input layout.
description: Journal of Computational Geometry, Vol. 7 No. 1 (2016)
title: Endangered Species Act (ESA) Section 7(a)(2) Biological Opinion Sitka Dock North Dolphins Expansion Project AKR0-2019-02310
titleType: Other
Creators: name: United States. National Marine Fisheries Service
Publisher: name: United States. National Marine Fisheries Service
Year: 2020

description: ESA Section 7 Consultation ; AKRO-2019-02310
Silhouette of a random polytope
Creators: name: Glisse, Marc
name: Lazard, Sylvain
name: Michel, Julien
name: Pouget, Marc
Publisher: name: Journal of Computational Geometry
Year: 2016

description: We consider random polytopes defined as the convex hull of a Poisson point process on a sphere in $\mathbb{R}^3$ such that its average number of points is $n$. We show that the expectation over all such random polytopes of the maximum size of their silhouettes viewed from infinity is $\Theta(\sqrt{n})$.
description: Journal of Computational Geometry, Vol. 7 No. 1 (2016)
Smoothed complexity of convex hulls by witnesses and collectors
Creators: name: Devillers, Olivier
name: Glisse, Marc
name: Goaoc, Xavier
name: Thomasse, Rémy
Publisher: name: Journal of Computational Geometry
Year: 2016

description: We present a simple technique for analyzing the size of geometric hypergraphs defined by random point sets. As an application we obtain upper and lower bounds on the smoothed number of faces of the convex hull under Euclidean and Gaussian noise and related results.
description: Journal of Computational Geometry, Vol. 7 No. 2 (2016): Special Issue of Selected Papers from SoCG 2015
2-manifold recognition is in logspace
Creators: name: Burton, Benjamin A
name: Elder, Murray
name: Kalka, Arkadius
name: Tillmann, Stephan
Publisher: name: Journal of Computational Geometry
Year: 2016

description: We prove that the homeomorphism problem for 2--manifolds can be decided in logspace. The proof relies on Reingold's logspace solution to the undirected $s,t$-connectivity problem in graphs.
description: Journal of Computational Geometry, Vol. 7 No. 1 (2016)
Strict confluent drawing
Creators: name: Eppstein, David
name: Holten, Danny
name: Löffler, Maarten
name: Nöllenburg, Martin
name: Speckmann, Bettina
name: Verbeek, Kevin
Publisher: name: Journal of Computational Geometry
Year: 2016

description: We define strict confluent drawing, a form of confluent drawing in which the existence of an edge is indicated by the presence of a smooth path through a system of arcs and junctions (without crossings), and in which such a path, if it exists, must be unique. We prove that it is NP-complete to determine whether a given graph has a strict confluent drawing but polynomial to determine whether it has an outerplanar strict confluent drawing with a fixed vertex ordering (a drawing within a disk, with the vertices placed in a given order on the boundary).
description: Journal of Computational Geometry, Vol. 7 No. 1 (2016)
A new algorithm for computing visibility graphs of polygonal obstacles in the plane
Creators: name: Chen, Danny Z.
name: Wang, Haitao
Publisher: name: Journal of Computational Geometry
Year: 2015

description: Given a set of $h$ pairwise disjoint polygonal obstacles with a total of $n$ vertices in the plane, the vertex-vertex visibility graph is an undirected graph whose nodes are vertices of the obstacles and whose edges are pairs of visible vertices. The vertex-edge and edge-edge visibility graphs are defined similarly. Ghosh and Mount gave a well-known output-sensitive $O(n\log n+k)$ time algorithm for computing these visibility graphs, where $k$ is the size of the corresponding graph. By developing new techniques based on an extended corridor structure, we augment Ghosh and Mount’s algorithm to build these visibility graphs in $O(n+h\log h+k)$ time, after the free space is triangulated. The new algorithm improves Ghosh and Mount’s algorithm by reducing its additive $O(n\log n)$ time factor to $O(n + h\log h)$. Like Ghosh and Mount’s algorithm, our algorithm can also compute several important structures such as the funnel structure and the enhanced visibility graph, which may have other applications.
description: Journal of Computational Geometry, Vol. 6 No. 1 (2015)
title: Reducing aluminium intake can minimise potential health risks: BfR Opinion No 045/2019 of 18 November 2019
Creators: name: Bundesinstitut Für Risikobewertung
Publisher: name: Bundesbehörden und Einrichtungen im Geschäftsbereich des Bundesministeriums für Ernährung und Landwirtschaft (BMEL)
Year: 2019
Subjects: subject: 000

description: BfR-Stellungnahmen, vol. 2019, no. 045
Identifying boosted hadronically decaying top quark using jet substructure in its center-of-mass frame
Creators: name: Chen, Chunhui
Publisher: name: arXiv
Year: 2013
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: In this paper we study the identification of boosted hadronically decaying top quarks using jet substructure in the center-of-mass frame of the jet. We demonstrate that the method can greatly reduce the QCD jet background while maintaining high identification efficiency of the boosted top quark even in a very high pileup condition. Applications to searches for heavy resonances that decay to a $t\bar{t}$ final state are also discussed.
description: 6 pages, 6 figures. Published in Phys. Rev. D 87, 074007 (2013). arXiv admin note: text overlap with arXiv:1112.2567
Shortest path in a polygon using sublinear space
Creators: name: Har-Peled, Sariel
Publisher: name: Journal of Computational Geometry
Year: 2015

description: We resolve an open problem due to Tetsuo Asano, showing how to compute the shortest path in a polygon, given in a read only memory, using sublinear space and subquadratic time. Specifically, given a simple polygon $P$ with $n$ vertices in a read only memory, and additional working memory of size $m$, the new algorithm computes the shortest path (in $P$) in $O( n^2 / m )$ expected time, assuming $m = O(n/\log^2 n)$. This requires several new tools, which we believe to be of independent interest. Specifically, we show that violator space problems, an abstraction of low dimensional linear-programming (and LP-type problems), can be solved using constant space and expected linear time, by modifying Seidel's linear programming algorithm and using pseudo-random sequences.
description: Journal of Computational Geometry, Vol. 7 No. 2 (2016): Special Issue of Selected Papers from SoCG 2015
Second order viscous corrections to the harmonic spectrum in heavy ion collisions
Creators: name: Teaney, Derek
name: Yan, Li
Publisher: name: arXiv
Year: 2013
Subjects: subject: Nuclear Theory (nucl-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We calculate the second order viscous correction to the kinetic distribution, $δf_{(2)}$, and use this result in a hydrodynamic simulation of heavy ion collisions to determine the complete second order correction to the harmonic spectrum, $v_n$. At leading order in a conformal fluid, the first viscous correction is determined by one scalar function, $χ_{0p}$. One moment of this scalar function is constrained by the shear viscosity. At second order in a conformal fluid, we find that $δf(\p)$ can be characterized by two scalar functions of momentum, $χ_{1p}$ and $χ_{2p}$. The momentum dependence of these functions is largely determined by the kinematics of the streaming operator. Again, one moment of these functions is constrained by the parameters of second order hydrodynamics, $τ_π$ and $λ_1$. The effect of $δf_{(2)}$ on the integrated flow is small (up to $v_4$), but is quite important for the higher harmonics at modestly-large $p_T$. Generally, $δf_{(2)}$ increases the value of $v_n$ at a given $p_T$, and is most important in small systems.
description: 20 pages and 3 figures. version has a slightly improved numerics for v5
Pattern overlap implies runaway growth in hierarchical tile systems
Creators: name: Doty, David
name: Chen, Ho-Lin
name: Manuch, Jan
name: Rafiey, Arash
name: Stacho, Ladislav
Publisher: name: Journal of Computational Geometry
Year: 2015

description: We show that in the hierarchical tile assembly model, if there is a producible assembly that overlaps a nontrivial translation of itself consistently (i.e., the pattern of tile types in the overlap region is identical in both translations), then arbitrarily large assemblies are producible. The significance of this result is that tile systems intended to controllably produce finite structures must avoid pattern repetition in their producible assemblies that would lead to such overlap. This answers an open question of Chen and Doty (SODA 2012), who showed that so-called "partial-order" systems producing a unique finite assembly and avoiding such overlaps must require time linear in the assembly diameter. An application of our main result is that any system producing a unique finite assembly is automatically guaranteed to avoid such overlaps, simplifying the hypothesis of Chen and Doty's main theorem.
description: Journal of Computational Geometry, Vol. 7 No. 2 (2016): Special Issue of Selected Papers from SoCG 2015
Studying the elastic properties of nanocrystalline copper using a model of randomly packed uniform grains
Creators: name: Gao, Guo-Jie J.
name: Wang, Yun-Jiang
name: Ogata, Shigenobu
Publisher: name: arXiv
Year: 2013
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We develop a new Voronoi protocol, which is a space tessellation method, to generate fully dense (containing no voids) nanocrystalline models of copper (Cu) with precise grain size control; we also perform uniaxial tensile tests using molecular dynamical (MD) simulations to measure the elastic moduli of the grain boundary and the grain interior components at 300 K. We find that the grain boundary deforms more locally compared with the grain core region under thermal vibrations and is elastically less stiff than the core component at finite temperature. The elastic modulus of the grain boundary is lower than 30% of that of the grain interior. Our results will aid in the development of more accurate continuum models of nanocrystalline metals.
description: 7 pages, 10 figures, 1 table