cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Electron orbital valves made of multiply connected armchair carbon nanotubes with mirror-reflection symmetry: tight-binding study
Creators: name: Kim, Gunn
name: Lee, Sang Bong
name: Lee, Hoonkyung
name: Ihm, Jisoon
Publisher: name: arXiv
Year: 2006
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: Using the tight-binding method and the Landauer-Büttiker conductance formalism, we demonstrate that a multiply connected armchair carbon nanotube with a mirror-reflection symmetry can sustain an electron current of the $π$-bonding orbital while suppress that of the $π$-antibonding orbital over a certain energy range. Accordingly, the system behaves like an electron orbital valve and may be used as a scanning tunneling microscope to probe pairing symmetry in d-wave superconductors or even orbital ordering in solids which is believed to occur in some transition-metal oxides.
description: 4 figures, 12 pages
From flesh and bone to bronze and stone : celebrating and commemorating the life of Queen Victoria in the British world 1897-1930
Creators: name: Sheldrick, Philip
Publisher: name: The Australian National University
Year: 2019
Subjects: subject: Victoria, Queen of Great Britain, 1819-1901 Monuments
subject: Queens Great Britain
subject: Monuments
subject: Memory Social aspects
subject: Great Britain History Victoria, 1837-1901.

description: Why is it that if you walk through many of the cities of the United Kingdom, Australia, India, Canada, New Zealand, or any part of what used to be the British world you will usually find at least one and sometimes more statues of Queen Victoria? In the last years of her life Queen Victoria enjoyed a special place in the hearts and minds of people across the world. At the turn of the twentieth century, Victoria was a celebrity above all others, charismatic, immensely popular and an almost untouchable icon. Strangely, Victoria gained this lofty status through her association with two very different, and it would seem conflicting ideas - imperialism and domesticity. This thesis investigates just how Queen Victoria gained that level of celebrity and then how it turned her from flesh and bone to bronze and stone in Britain and across the British world from 1897 to 1930. It argues that two events in particular are the key to this transformation. The first, the Diamond Jubilee celebrations of 1897, transformed her in the eyes of the public into the representative figure of an entire age. The second, her death and funeral in early 1901, had such a public impact that it triggered the numerous commemorative efforts at home and abroad in the many years that followed. No work published to date has looked in detail at the historical significance of the celebration and monumental commemoration of Queen Victoria in the context of British and British imperial identity. This thesis aims to fill this gap in the work done so far on the imagery of Queen Victoria while also breaking new ground in considering just how her iconic status came into existence.
Coverage-Conscious Connectivity Restoration in Mobile Sensor Networks
Creators: name: Tamboli, Neelofer
Publisher: name: Maryland Shared Open Access Repository
Year: 2009
Subjects: Connectivity
Coverage
Energy efficient
Mobile sensor network

description: Mobile sensor networks rely heavily on inter-sensor connectivity for collection of data. Nodes in these networks monitor different regions of an area of interest and collectively present a global overview of monitored activities. Since failure of a sensor leads to loss of connectivity it may cause a partitioning of the network. A number of approaches have been proposed that pursue node relocation to restore connectivity. However, these approaches tend to ignore the possible loss of coverage in some areas, either due to the failure itself or due to their connectivity-limited focus. The thesis opts to address the connectivity and coverage concerns in an integrated manner. A novel Coverage Conscious Connectivity Restoration (C3 orithm is presented. C3 lves neighbors of the failed node to recover from the failure. Each neighbor temporarily relocates to substitute the failed node, one at a time, and then returns back to its original location. This leads to intermittent connectivity and monitoring of all the originally covered spots. This thesis also presents Energy-Centric optimized Recovery algorithm (ECR), an optimized version of C3  is geared for energy efficiency. Both C3 ECR are validated through simulation.
List Homomorphisms by Deleting Edges and Vertices: Tight Complexity Bounds for Bounded-Treewidth Graphs.
Creators: name: Esmer, Baris Can
name: Focke, Jacob
name: Marx, Dániel
name: Rzazewski, Pawel
Publisher: name: CISPA
Year: 2024

description: The goal of this paper is to investigate a family of optimization problems arising from list homomorphisms, and to understand what the best possible algorithms are if we restrict the problem to bounded-treewidth graphs. Given graphs G, H, and lists L(v) ⊆ V(H) for every v ∈ V(G), a list homomorphism from (G,L) to H is a function f:V(G) → V(H) that preserves the edges (i.e., uv ∈ E(G) implies f(u)f(v) ∈ E(H)) and respects the lists (i.e., f(v) ∈ L(v)). The graph H may have loops. For a fixed H, the input of the optimization problem LHomVD(H) is a graph G with lists L(v), and the task is to find a set X of vertices having minimum size such that (G-X,L) has a list homomorphism to H. We define analogously the edge-deletion variant LHomED(H), where we have to delete as few edges as possible from G to obtain a graph that has a list homomorphism. This expressive family of problems includes members that are essentially equivalent to fundamental problems such as Vertex Cover, Max Cut, Odd Cycle Transversal, and Edge/Vertex Multiway Cut. For both variants, we first characterize those graphs H that make the problem polynomial-time solvable and show that the problem is NP-hard for every other fixed H. Second, as our main result, we determine for every graph H for which the problem is NP-hard, the smallest possible constant c_H such that the problem can be solved in time c^t_H⋅ n^{𝒪(1)} if a tree decomposition of G having width t is given in the input. Let i(H) be the maximum size of a set of vertices in H that have pairwise incomparable neighborhoods. For the vertex-deletion variant LHomVD(H), we show that the smallest possible constant is i(H)+1 for every H: - Given a tree decomposition of width t of G, LHomVD(H) can be solved in time (i(H)+1)^t⋅ n^{𝒪(1)}. - For any ε > 0 and H, an (i(H)+1-ε)^t⋅ n^{𝒪(1)} algorithm would violate the Strong Exponential-Time Hypothesis (SETH). The situation is more complex for the edge-deletion version. For every H, one can solve LHomED(H) in time i(H)^t⋅ n^{𝒪(1)} if a tree decomposition of width t is given. However, the existence of a specific type of decomposition of H shows that there are graphs H where LHomED(H) can be solved significantly more efficiently and the best possible constant can be arbitrarily smaller than i(H). Nevertheless, we determine this best possible constant and (assuming the SETH) prove tight bounds for every fixed H.
Design and Analysis of Maximum Simplex Volume-based Endmember Extraction Algorithms
Creators: name: Wu, Chao-Cheng
Publisher: name: Maryland Shared Open Access Repository
Year: 2009
Subjects: Causal N-FINDR
Endmember Extraction Algorithms
Initialization Driven N-FINDR
Maximum Simplex Volume
Random N-FINDR
Sequential N-FINDR

description: Endmember extraction is a fundamental task and has been found in many applications  in hyperspectral data exploitation such as anomaly detection, spectral unmixing,  classification, data compression, image analysis etc. Since an endmember is defined as a  pure, idealized signature for a spectral class, it provides first hand information for image  understanding and analysis. Many algorithms have been designed and developed for  endmember extraction in the past. One of major criteria, maximum simplex volume  ( MSV) has been used for this purpose. One best well- known Endmember Extraction  Algorithm ( EEA) in this category is N- finder algorithm ( N- FINDR) developed by Winter.  However there are many issues arising in its practical implementation. The research  proposed in this dissertation is to investigate and resolve these issues. As a result, N-FINDR  has been either re- invented to derive new algorithms such as Simplex Growing  Algorithm ( SGA) and Random N- FINDR ( RN- FINDR) or re- designed to better suit  practical implementation such as SeQuential N- FINDR ( SQ N- FINDR), SuCcessive N-FINDR  ( SC N- FINDR), Initialization- Driven N- FINDR ( ID N- FINDR) and Causal N-FINDR.  In order to substantiate all the algorithms proposed in this dissertation, synthetic  image- based experiments are conducted for validation. To further demonstrate their  utility in real applications two real hyperspectral image data sets are also performed for  experiments. Finally, a comparative analysis between N- FINDR and other popular EEAs  is also studied to explore their relationships.
Derivative sources in lattice spectroscopy of excited light-quark mesons
Creators: name: Gattringer, Christof
name: Glozman, Leonid Ya.
name: Lang, C. B.
name: Mohler, Daniel
name: Prelovsek, Sasa
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Lattice (hep-lat)
subject: FOS: Physical sciences

description: We construct efficient interpolating fields for lattice spectroscopy of mesons by applying covariant derivatives on Jacobi smeared quark sources. These interpolators are tested in a quenched calculation of excited mesons based on the variational method. We present results for pseudoscalar, scalar, vector and pseudovector mesons.
description: 10 pages, tables added, final version
Root organogenesis in Medicago truncatula
Creators: name: Holmes, Peta Dee
Publisher: name: The Australian National University
Year: 2018
Subjects: subject: QK665.H65 2011
subject: Medicago Morphogenesis
subject: Roots (Botany)
subject: Proteomics
subject: Transcription factors
subject: Genetic transcription

description: Plant stem cells are contained within niches like the root apical meristem (RAM) which create new cells for organ growth, plant stem cells may also be initiated post-embryogenesis like for the development of lateral roots. Secondary growth from the meristems of the vascular and cork cambia also occurs in roots and in some species specialised roots are formed for storage, in response to environmental cues and symbiotic and pathogenic microorganisms. Thus root organogenesis provides a widely variable model to examine one of biology's great questions, how can stem cells be created and maintained and how is differentiation specified and controlled? This thesis describes original proteomic and transcriptomic approaches to gene discovery in a variety of root organogenesis systems using the model legume Medicago truncatula. I used proteomics to compare the meristem and differentiating zones from primary and lateral roots and present and examination the effect of meristem inhibiting herbicide acetohydroxyacid synthase on the meristem proteome. I used transcriptomics to characterise the Medicago RAM by comparing the root meristem and non-meristem and extended this microarray analysis further to examine the very early steps of root formation in an in vitro root organogenesis system. These experiments have identified a host of transcription factors that are commonly expressed in root meristems, these genes will have an important role in future studies of the genetic networks controlling plant stem cells in root and nodule organogenesis.
Student observations and explanations of a physical phenomenon : the Cartesian Diver
Creators: name: Adler, J. Douglas
Publisher: name: University of British Columbia
Year: 2009

description: This study explored student observations and explanations of the Cartesian Diver. The study was conducted in a Grade 6/7 class in the lower mainland of Vancouver it. chronicled and categorized the developing understanding of three pairs of students. Each dyad participated in four events. Each event presented a unique variation of the Cartesian Diver. The first and third event involved a working Cartesian Diver, while events two and four required the students to construct a Cartesian Diver. Throughout the events, the researcher videotaped each pair's manipulations, observations and explanations. The data was analyzed using two established frameworks (Gunstone, 1998; Frazier, 1995). Students were able to construct a working Cartesian Diver and offer many explanations for its functioning. Student explanations of the Cartesian Diver were constructed from the data. The number of explanations increased as the students became familiar with the equipment and the variables which determine the behaviour of the Cartesian Diver. While many of the explanations were scientific, the students could only explain what they saw; student theories were context driven. None of the students was able to formulate a comprehensive theory to explain the Cartesian Diver.
Toward precise simulations of the coupled ultrafast dynamics of electrons and atomic vibrations in materials
Creators: name: Tong, Xiao
name: Bernardi, Marco
Publisher: name: arXiv
Year: 2020
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Ultrafast spectroscopies can access the dynamics of electrons and nuclei at short timescales, shedding light on nonequilibrium phenomena in materials. However, development of accurate calculations to interpret these experiments has lagged behind as widely adopted simulation schemes are limited to sub-picosecond timescales or employ simplified interactions lacking quantitative accuracy. Here we show a precise approach to obtain the time-dependent populations of nonequilibrium electrons and atomic vibrations (phonons) up to tens of picoseconds, with a femtosecond time resolution. Combining first-principles electron-phonon and phonon-phonon interactions with a parallel numerical scheme to time-step the coupled electron and phonon Boltzmann equations, our method provides unprecedented microscopic insight into scattering mechanisms in excited materials. Focusing on graphene as a case study, we demonstrate calculations of ultrafast electron and phonon dynamics, transient optical absorption, structural snapshots and diffuse X-ray scattering. Our first-principles approach paves the way for quantitative atomistic simulations of ultrafast dynamics in materials.
Baryon Triality and Neutrino Masses from an Anomalous Flavor U(1)
Creators: name: Dreiner, Herbi K.
name: Luhn, Christoph
name: Murayama, Hitoshi
name: Thormeier, Marc
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We construct a concise U(1)_X Froggatt-Nielsen model in which baryon triality, a discrete gauge Z_3 symmetry, arises from U(1)_X breaking. The proton is thus stable, however, R-parity is violated. With the proper choice of U(1)_X charges we can obtain neutrino masses and mixings consistent with an explanation of the atmospheric and solar neutrino anomalies in terms of neutrino oscillations, with no right-handed neutrinos required. The only mass scale apart from M_grav is m_3/2 ~ m_soft.
description: matches published version, typos corrected, references added, 54 pages, 3 figures, 5 tables
title: Conservation across the cultural divide : comparative perspectives on local communities and protected area management in the Asia-Pacific region
title: Tracing the kaleidoscope : comparative perspectives on culture and conservation in the australasian region
titleType: AlternativeTitle
title: To the head of the crocodile
titleType: AlternativeTitle
Creators: name: McClean, Nick
Publisher: name: The Australian National University
Year: 2018

description: The widespread rise of a modern conservation ethic has seen national parks, archaeological parks, nature reserves and a host of other forms of protected area (PA) spread to almost every corner of the globe. As a body of thought and practice that was developed initially in western industrialised societies, the spread of modern, state initiated conservation has been a spectacular success as far as increasing the total area of protected land and waters is concerned, but it has not always been a straightforward process as far as the on ground work of managing landscapes for conservation is concerned. In particular, the ideal of state run PAs preserving pristine natural areas has proven difficult to reconcile with on the ground realities in developing countries and on Indigenous lands, where sometimes tens of thousands of people will live in and depend on protected landscapes for economic and cultural reasons. 30 years after participatory planning methods and co-management emerged, where are we up to with cross-cultural collaborations in conservation? An initial point to be made is that interactions between western oriented conservationists and local, culturally distinct communities have been sustained to the extent that at times PAs are not only the subject of intercultural dialogue, but have become the products of intercultural engagement. PAs in some cases have moved beyond a standoff between western and non-western views of nature, culture and conservation, and are now in some important ways bi-cultural entities. What are the implications of this process for on-ground conservation work? Presenting case material from Australia and Timor-Leste, I{u2019}ll focus on how the growth of the conservation estate in Australia has been fuelled in part by the growth in Indigenous owned land, and secondly on how traditional institutions in Timor-Leste have played a key role in facilitating social and political change in the past. Both these cases support the argument that developing {u2018}bi-cultural{u2019} PAs can broker alliances in support of conservation among local communities.
The effect of radiation pressure on virial black hole mass estimates and the case of Narrow Line Seyfert 1 galaxies
Creators: name: Marconi, Alessandro
name: Axon, David
name: Maiolino, Roberto
name: Nagao, Tohru
name: Pastorini, Guia
name: Pietrini, Paola
name: Robinson, Andrew
name: Torricelli, Guidetta
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We consider the effect of radiation pressure from ionizing photons on black hole (BH) mass estimates based on the application of the virial theorem to broad emission lines in AGN spectra. BH masses based only on the virial product V^2R and neglecting the effect of radiation pressure can be severely underestimated especially in objects close to the Eddington limit. We provide an empirical calibration of the correction for radiation pressure and we show that it is consistent with a simple physical model in which BLR clouds are optically thick to ionizing radiation and have average column densities of NH~10^23 cm^-2. This value is remarkably similar to what is required in standard BLR photoionization models to explain observed spectra. With the inclusion of radiation pressure the discrepancy between virial BH masses based on single epoch spectra and on reverberation mapping data drops from 0.4 to 0.2 dex rms. The use of single epoch observations as surrogates of reverberation mapping campaigns can thus provide more accurate BH masses than previously thought. Finally, we show that Narrow Line Seyfert 1 (NLS1) galaxies have apparently low BH masses because they are radiating close to their Eddington limit. After the radiation pressure correction, NLS1 galaxies have BH masses similar to other broad line AGNs and follow the same MBH-sigma/L relations as other active and normal galaxies. Radiation forces arising from ionizing photon momentum deposition constitute an important physical effect which must be taken into account when computing virial BH masses.
description: To appear in the Astrophysical Journal, May 1 issue
Estimation of the electrostatic effects in the LISA-Pathfinder critical test mass dynamics via the method of moments
Creators: name: Zanoni, Carlo
name: Bortoluzzi, Daniele
Publisher: name: arXiv
Year: 2021
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: LISA-Pathfinder is an ESA space mission flown between 2015 and 2017 to demonstrate a technological maturity sufficient for building a gravitational waves telescope in space, such as the Laser Interferometer Space Antenna (LISA). A pair of cubic test masses is hosted inside the LISA-Pathfinder spacecraft and shielded from any force other than the interplanetary gravitational field. The purity of the shielding gives the performance of the mission. There are a number of aspects that had to be confirmed in-flight. One of them is the transition phase from the launch configuration, when the test masses are locked, to the science free-falling configuration. Each test mass is initially released from the mechanical constraints via a dedicated mechanism and then captured by an electrostatic control system. In fact, each test mass is surrounded by a set of electrodes for actuation and sensing purposes. The performance criterion of the release is the final velocity of the test mass relative to the spacecraft, with an upper threshold set to 5 $μm/s$. The LISA-Pathfinder first in-flight release velocities highlighted an unexpected dynamics with large linear and angular velocities. The electrostatic control was successful, but only relying on a manual procedure that cannot be considered as baseline for LISA. This paper helps investigating the in-flight non-compliance by dealing with the modeling of the electrostatic environment around each test mass and its contribution to the release and capture dynamics. The electrostatic model is based on the method of moments, a boundary element numerical technique suitable for estimating forces and capacitances between conductors. We also provide a short overview of the method, which can be used for the analysis of other phenomena within LISA and for the design of future gravitational waves telescopes and space projects.
Line Strengths in Early-Type Cluster Galaxies at z=0.33: Implications for alpha/Fe, Nitrogen and the Histories of E/S0s
Creators: name: Kelson, Daniel D.
name: Illingworth, Garth D.
name: Franx, Marijn
name: van Dokkum, P. G.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: [Heavily Abbreviated] In this paper we analyze previously published spectra with high signal-to-noise ratios of E/S0 galaxies in the rich cluster CL1358+62 at z=0.33, and introduce techniques for fitting stellar population models to the data. Here we focus on the 19 E and S0 galaxies with an homogeneous set of eight blue Lick indices. We explore the galaxy properties using six-parameter stellar population models from the literature, and describe an approach for fitting the models differentially, such that the largest systematic errors are avoided. We find: (1) no differences between the stellar population parameters of Es and S0s, at fixed sigma; (2) the stars in the Es and S0s are uniformly old, consistent with previously published results using M/L ratios; (3) a significant correlation of [Z/H] with sigma, in a manner consistent with the observed B-V colors of the galaxies; (4) no significant correlation of [alpha/Fe] with sigma; and (5) a significant anti-correlation of [alpha/N] with [Z/H], which we interpret as the signature of secondary nitrogen. Neither [alpha/C], nor [alpha/Ca] shows significant variation. While the differences between our conclusions and the current view of stellar populations may point to serious deficiencies, our deduced correlation of mean metallicity with sigma does reproduce the B-V colors of the galaxies, as well as the slope of the local Mg-sigma relation. In matching the inferred population trends with published data on nearby galaxies, the line strength-line width relations match well, save for the narrow iron indices. Taken together, these results reduce early-type galaxies in clusters to a family with one-parameter, velocity dispersion, greatly simplifying scenarios for their formation and evolution.
description: Accepted for publication in ApJ. 15 figures. (the new version has had some very minor changes, and some more typographical errors fixed)
Reconstruct Your Previous Conversations! Comprehensively Investigating Privacy Leakage Risks in Conversations with GPT Models
Creators: name: Chu, Junjie
name: Sha, Zeyang
name: Backes, Michael
name: Zhang, Yang
Publisher: name: CISPA
Year: 2024

description: Significant advancements have recently been made in large language models, represented by GPT models.
Users frequently have multi-round private conversations with cloud-hosted GPT models for task optimization.
Yet, this operational paradigm introduces additional attack surfaces, particularly in custom GPTs and hijacked chat sessions.
In this paper, we introduce a straightforward yet potent Conversation Reconstruction Attack.
This attack targets the contents of previous conversations between GPT models and benign users, i.e., the benign users' input contents during their interaction with GPT models.
The adversary could induce GPT models to leak such contents by querying them with designed malicious prompts.
Our comprehensive examination of privacy risks during the interactions with GPT models under this attack reveals GPT-4's considerable resilience.
We present two advanced attacks targeting improved reconstruction of past conversations, demonstrating significant privacy leakage across all models under these advanced techniques.
Evaluating various defense mechanisms, we find them ineffective against these attacks.
Our findings highlight the ease with which privacy can be compromised in interactions with GPT models, urging the community to safeguard against potential abuses of these models' capabilities.
Domain wall solution of the Skyrme model
Creators: name: Shi, Chang-Guang
name: Hirayama, Minoru
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: A class of domain-wall-like solutions of the Skyrme model is obtained analytically. They are described by the tangent hyperbolic function, which is a special limit of the Weierstrass $\wp$ function. The behavior of one of the two terms in the static energy density is like that of a domain wall. The other term in the static energy density does not vanish but becomes constant at the points far apart from the wall.
description: 17 pages, 6 eps figures
Hitting Meets Packing: How Hard Can It Be?
Creators: name: Focke, Jacob
name: Frei, Fabian
name: Li, Shaohua
name: Marx, Dániel
name: Schepper, Philipp
name: Sharma, Roohani
name: W\kegrzycki, Karol
Publisher: name: CISPA
Year: 2024

description: We study a general family of problems that form a common generalization of classic hitting (also referred to as covering or transversal) and packing problems. An instance of 𝒳-HitPack asks: Can removing k (deletable) vertices of a graph G prevent us from packing 𝓁 vertex-disjoint objects of type 𝒳? This problem captures a spectrum of problems with standard hitting and packing on opposite ends. Our main motivating question is whether the combination 𝒳-HitPack can be significantly harder than these two base problems. Already for one particular choice of 𝒳, this question can be posed for many different complexity notions, leading to a large, so-far unexplored domain at the intersection of the areas of hitting and packing problems. At a high level, we present two case studies: (1) 𝒳 being all cycles, and (2) 𝒳 being all copies of a fixed graph H. In each, we explore the classical complexity as well as the parameterized complexity with the natural parameters k+𝓁 and treewidth. We observe that the combined problem can be drastically harder than the base problems: for cycles or for H being a connected graph on at least 3 vertices, the problem is Σ₂^𝖯-complete and requires double-exponential dependence on the treewidth of the graph (assuming the Exponential-Time Hypothesis). In contrast, the combined problem admits qualitatively similar running times as the base problems in some cases, although significant novel ideas are required. For 𝒳 being all cycles, we establish a 2^{poly(k+𝓁)}⋅ n^{𝒪(1)} algorithm using an involved branching method, for example. Also, for 𝒳 being all edges (i.e., H = K₂; this combines Vertex Cover and Maximum Matching) the problem can be solved in time 2^{poly(tw)}⋅ n^{𝒪(1)} on graphs of treewidth tw. The key step enabling this running time relies on a combinatorial bound obtained from an algebraic (linear delta-matroid) representation of possible matchings.
Atomic ionization by multicharged ions interpreted in terms of poles in the velocity complex space
Creators: name: Miraglia, J. E.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: We study the single ionization of hydrogen and helium by the impact of a highly-charged Coulomb projectile. To interpretate the cross section we introduce a diagonal Padé approximant. We find that the use of Padé% [4,4] describes very well the Continnum Distorted Wave Eikonal Initial State theory within its range of validity. The nodes of the denominator of the Pad% é approximant give rise to four poles in the velocity complex plane: two in the upper plane and their conjugate in the lower plane. The dependence of these poles with the projectile charge can be reasonably fitted to give a closed-form for the ionization cross section, resulting a scaling very near to the one of Janev and Presnyakov. The experiments available were described very well in its entire velocity range with the use of a Padé[8,8], having four poles in the upper plane and their conjugate in the lower plane. We conclude that the poles of the Padé approximant seem to have all the information of the total ionization cross section
description: 18 pages, 4 figures and 3 tables
Schon, Dietmar (Hrsg.): Identität und Authentizität von Kirchen im "globalen Dorf"
Creators: name: Önder, Josef
Publisher: name: Ökumenische Rundschau
Year: 2025

description: Ökumenische Rundschau, Bd. 69 Nr. 4 (2020): Ökumenische Rundschau, Band 69, Heft 4
Distributed Approach for Mitigating Coverage Loss in Heterogeneous Wireless Sensor Networks
Creators: name: Kasinathan, Kavin Rathinam
Publisher: name: Maryland Shared Open Access Repository
Year: 2011
Subjects: Coverage
Fault tolerance
Sensor Networks

description: In a heterogeneous wireless sensor network, nodes with different sensing capabilities are dispersed throughout an area of interest. Nodes with similar capabilities are not necessarily collocated. When a node fails, the area in the vicinity of such a node is left uncovered and the application may be negatively impacted. In this thesis, we present a distributed algorithm for mitigating the coverage loss caused by the failure of a sensor node. The proposed algorithm looks for one or multiple nodes that can be repositioned in order to fill the coverage gap. A search is conducted within the 2-hop neighborhood to identify a node or a combination of more than one node that can collectively possess the capabilities of the failed node. In order to maximize the performance of the network, the replaceable nodes are chosen such that there is a minimum coverage and connectivity impact on the network after replacement. In the addition, the distance a node will travel to replace the failed node is also taken into consideration to limit the recovery overhead.
A Far Ultraviolet Archival Study of Cataclysmic Variables: I. FUSE and HST/STIS Spectra of the Exposed White Dwarf in Dwarf Nova Systems
Creators: name: Godon, P.
name: Sion, E. M.
name: Barrett, P. E.
name: Hubeny, I.
name: Linnell, A. P.
name: Szkody, P.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present a synthetic spectral analysis of Far Ultraviolet Spectroscopic Explorer (FUSE) and Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS) spectra of 5 dwarf novae above and below the period gap during quiescence. We use our synthetic spectral code, including options for the treatment of the hydrogen quasi-molecular satellite lines (for low temperature stellar atmospheres), NLTE approximation (for high temperature stellar atmospheres), and for one system (RU Peg) we model the interstellar medium (ISM) molecular and atomic hydrogen lines. In all the systems presented here the FUV flux continuum is due to the WD. These spectra also exhibit some broad emission lines. In this work we confirm some of the previous FUV analysis results but we also present new results. For 4 systems we combine the FUSE and STIS spectra to cover a larger wavelength range and to improve the spectral fit. This work is part of our broader HST archival research program, in which we aim to provide accurate system parameters for cataclysmic variables above and below the period gap by combining FUSE and HST FUV spectra.
description: 49 pages (preprint format), 11 figures, 6 tables, ApJ in press
Tasting Nuclear Pasta Made with Classical Molecular Dynamics Simulations
Creators: name: Li, Bao-An
Publisher: name: arXiv
Year: 2021
Subjects: subject: Nuclear Theory (nucl-th)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: Nuclear clusters or voids in the inner crust of neutron stars were predicted to have various shapes collectively nicknamed nuclear pasta. The recent review in Ref. \cite{Lopez1} by López, Dorso and Frank summarized their systematic investigations into properties especially the morphological and thermodynamical phase transitions of the nuclear pasta within a Classical Molecular Dynamics model, providing further stimuli to find more observational evidences of the predicted nuclear pasta in neutron stars.
description: Invited View & Perspective
Discovering and Characterizing Hidden Variables in Streaming Multivariate Time Series
Creators: name: Ray, Soumi
Publisher: name: Maryland Shared Open Access Repository
Year: 2010
Subjects: Hidden variables
Linear Dynamical systems
Machine Learning
Neural Networks
Theoretical entities

description: Hidden variables in time series data arise naturally in many domains, such as robotics, industrial process control, finance, medicine, and climatology. In many cases, however, variables that are known to be causally relevant to the observed behavior of the true model cannot be measured directly, or the existence of such variables is unknown.  This thesis first presents a neural network architecture, called the LO-net, for inferring both the existence and the values of hidden variables in streaming multivariate time series, leading to a deeper understanding of the domain and to more accurate predictions. The core idea is to first make predictions with one network (the observable or O-net) based on a time delay embedding, following this with a gradual reduction in the temporal scope of the embedding, thus forcing a second network (the latent or L-net) to learn to approximate the value of a single hidden variable. This estimate is then input to the O-net using the original time delay embedding. Experiments show the utility of this proposed approach using discrete time dynamical systems in which some of the state variables are hidden, and sensor data obtained from the camera of a mobile robot in which the sizes and locations of objects in the visual field are observed but their sizes and locations (distances) in the three-dimensional world are not. In  some situations, the L-net is seen to approximate the output from the O-net instead of learning the hidden variable. To avoid this undesirable behavior, the LO-net is regularized. Experimental results of this approach have been shown using different regularization terms. A second method for discovering hidden variables in multivariate dynamical systems starts with a Linear Dynamical System (LDS) where a variable is hidden. A new LDS is formed with random values for the initial value and weights on the the hidden variable. These parameters are found by gradient descent on the prediction errors with respect to the observable variables. Closed-form iterative solutions for the gradients with respect to the initial values and weights of the hidden variable in the LDS framework are presented. This method is then extended to non-linear dynamical systems such as the robot data. Experimental results show that this method provides good predictions. The contributions of this thesis are two novel methods for discovering and characterizing hidden variables in multivariate time series data and an evaluation of these methods on various dynamical systems and real-world data. In most of the previous work the aim is to design better models that work with hidden variables. Our aim is to actually discover and quantify the hidden variables in order to improve the understanding of the over all model.
Radiative Properties of the Stueckelberg Mechanism
Creators: name: Marshall, T. J.
name: McKeon, D. G. C.
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We examine the mechanism for generating a mass for a U(1) vector field introduced by Stueckelberg. First, it is shown that renormalization of the vector mass is identical to the renormalization of the vector field on account of gauge invariance. We then consider how the vector mass affects the effective potential in scalar quantum electrodynamics at one-loop order. The possibility of extending this mechanism to couple, in a gauge invariant way, a charged vector field to the photon is discussed.
description: 8 pages, new Introduction, added References
Detection of unsafe actions in laparoscopic cholecystectomy videos
Creators: name: Lahane, Ashwini Chandrakant
Publisher: name: Maryland Shared Open Access Repository
Year: 2011
Subjects: healthcare
laparoscopic cholecystectomy
machine learning
Situation awareness
video analysis

description: Laparoscopic cholecystectomy has replaced open cholecystectomy as the first-choice of treatment for gallstones and inflammation of the gallbladder. The operation is minimally invasive and requires a camera to be inserted into patient's abdominal cavity. This limits the surgeon's view of the surgical site to the camera's projection. Due to the lack of tactile sensation and three dimensional visual feedback, there are possibilities of certain surgical injuries to the adjacent anatomical structures such as the cystic artery, common bile duct, duodenum or the small intestine. To address this challenge we have developed a system that analyzes images from the laparoscopic videos. It indicates the possibility of an injury to the cystic artery by automatically detecting the proximity of the surgical instruments with respect to the cystic artery. The system uses machine learning algorithm to classify images and warn surgeons against probable unsafe actions. The approach has been successful in classifying images with an accuracy of 90.14%.
Detecting Spam Blogs: An Adaptive Online Approach
Creators: name: Kolari, Pranam
Publisher: name: Maryland Shared Open Access Repository
Year: 2008
Subjects: spam
weblogs
spam blogs
machine learning
social media
Computer Science (0984)

description: Weblogs, or blogs are an important new way to publish information, engage in discussions, and form communities on the Internet. Blogs are a global phenomenon, and with numbers well over 100 million they form the core of the emerging paradigm of Social Media. While the utility of blogs is unquestionable, a serious problem now afflicts them, that of spam. Spam blogs, or splogs are blogs with auto-generated or plagiarized content with the sole purpose of hosting profitable contextual ads and/or inflating importance of linked-to sites. Though estimates vary, splogs account for more than 50% of blog content, and present a serious threat to their continued utility. Splogs impact search engines that index the entire Web or just the blogosphere by increasing computational overhead and reducing user satisfaction. Hence, search engines try to minimize the influence of spam, both prior to indexing and after indexing, by eliminating splogs, comment spam, social media spam, or generic web spam. In this work we further the state of the art of splog detection prior to indexing. First, we have identified and developed techniques that are effective for splog detection in a supervised machine learning setting. While some of these are novel, a few others confirm the utility of techniques that have worked well for e-mail and Web spam detection in a new domain i.e. the blogosphere. Specifically, our techniques identify spam blogs using URL, home-page, and syndication feeds. To enable the utility of our techniques prior to indexing, the emphasis of our effort is fast online detection. Second, to effectively utilize identified techniques in a real-world context, we have developed a novel system that filters out spam in a stream of update pings from blogs. Our approach is based on using filters serially in increasing cost of detection that better supports balancing cost and effectiveness. We have used such a system to support multiple blog related projects, both internally and externally. Next, motivated by these experiences, and input room real-world deployments of our techniques for over ayear, we have developed an approach for updating classifiers in an adversarial setting. We show how an ensemble of classifiers can co-evolve and adapt when used on a stream of unlabeled instances susceptible to concept drift. We discuss how our system is amenable to such evolution by discussing approaches that can feed into it. Finally, over the course of this work we have characterized the specific nature of spam blogs along various dimensions, formalized the problem and created general awareness of the issue. We are the first to formalize and address the problem of spam in blogs and identify the general problem of spam in Social Media. We discuss how lessons learned can guide follow-up work on spam in social media, an important new problem on the Web.
Vortices in U(1) Noncommutative Gauge Fields
Creators: name: Falomir, H.
name: Gamboa, J.
name: Lopez-Sarrion, J.
name: Mendez, F.
name: da Silva, A. J.
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Charged vortex solutions for noncommutative Maxwell-Higgs model in 3+1 dimensions are found. We show that the stability of these vortex solutions is spoiled out for some, large enough, noncommutativity parameter. A non topological charge, however, is induced by noncommutative effects.
description: references added, slight modifications in the introduction and conclusions. To be published in PRD
LISACode : A scientific simulator of LISA
Creators: name: Petiteau, Antoine
name: Auger, G.
name: Halloin, H.
name: Jeannin, O.
name: Plagnol, E.
name: Pireaux, Sophie
name: Regimbau, Tania
name: Vinet, J. -Y.
Publisher: name: arXiv
Year: 2008
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: A new LISA simulator (LISACode) is presented. Its ambition is to achieve a new degree of sophistication allowing to map, as closely as possible, the impact of the different sub-systems on the measurements. LISACode is not a detailed simulator at the engineering level but rather a tool whose purpose is to bridge the gap between the basic principles of LISA and a future, sophisticated end-to-end simulator. This is achieved by introducing, in a realistic manner, most of the ingredients that will influence LISA's sensitivity as well as the application of TDI combinations. Many user-defined parameters allow the code to study different configurations of LISA thus helping to finalize the definition of the detector. Another important use of LISACode is in generating time series for data analysis developments.
Physics-Aware Gaussian Processes in Remote Sensing
Creators: name: Camps-Valls, Gustau
name: Martino, Luca
name: Svendsen, Daniel H.
name: Campos-Taberner, Manuel
name: Muñoz-Marí, Jordi
name: Laparra, Valero
name: Luengo, David
name: García-Haro, Francisco Javier
Publisher: name: arXiv
Year: 2020
Subjects: subject: Signal Processing (eess.SP)
subject: Applications (stat.AP)
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Computer and information sciences

description: Earth observation from satellite sensory data poses challenging problems, where machine learning is currently a key player. In recent years, Gaussian Process (GP) regression has excelled in biophysical parameter estimation tasks from airborne and satellite observations. GP regression is based on solid Bayesian statistics and generally yields efficient and accurate parameter estimates. However, GPs are typically used for inverse modeling based on concurrent observations and in situ measurements only. Very often a forward model encoding the well-understood physical relations between the state vector and the radiance observations is available though and could be useful to improve predictions and understanding. In this work, we review three GP models that respect and learn the physics of the underlying processes in the context of both forward and inverse modeling. After reviewing the traditional application of GPs for parameter retrieval, we introduce a Joint GP (JGP) model that combines in situ measurements and simulated data in a single GP model. Then, we present a latent force model (LFM) for GP modeling that encodes ordinary differential equations to blend data-driven modeling and physical constraints of the system governing equations. The LFM performs multi-output regression, adapts to the signal characteristics, is able to cope with missing data in the time series, and provides explicit latent functions that allow system analysis and evaluation. Finally, we present an Automatic Gaussian Process Emulator (AGAPE) that approximates the forward physical model using concepts from Bayesian optimization and at the same time builds an optimally compact look-up-table for inversion. We give empirical evidence of the performance of these models through illustrative examples of vegetation monitoring and atmospheric modeling.