2,344 research outputs found
FPTAS for Hardcore and Ising Models on Hypergraphs
Hardcore and Ising models are two most important families of two state spin
systems in statistic physics. Partition function of spin systems is the center
concept in statistic physics which connects microscopic particles and their
interactions with their macroscopic and statistical properties of materials
such as energy, entropy, ferromagnetism, etc. If each local interaction of the
system involves only two particles, the system can be described by a graph. In
this case, fully polynomial-time approximation scheme (FPTAS) for computing the
partition function of both hardcore and anti-ferromagnetic Ising model was
designed up to the uniqueness condition of the system. These result are the
best possible since approximately computing the partition function beyond this
threshold is NP-hard. In this paper, we generalize these results to general
physics systems, where each local interaction may involves multiple particles.
Such systems are described by hypergraphs. For hardcore model, we also provide
FPTAS up to the uniqueness condition, and for anti-ferromagnetic Ising model,
we obtain FPTAS where a slightly stronger condition holds
Planning and Optimization During the Life-Cycle of Service Level Agreements for Cloud Computing
Ein Service Level Agreement (SLA) ist ein elektronischer Vertrag zwischen dem Kunden
und dem Anbieter eines Services. Die beteiligten Partner kl aren ihre Erwartungen
und Verp
ichtungen in Bezug auf den Dienst und dessen Qualit at. SLAs werden
bereits f ur die Beschreibung von Cloud-Computing-Diensten eingesetzt. Der
Diensteanbieter stellt sicher, dass die Dienstqualit at erf ullt wird und mit den Anforderungen
des Kunden bis zum Ende der vereinbarten Laufzeit ubereinstimmt.
Die Durchf uhrung der SLAs erfordert einen erheblichen Aufwand, um Autonomie,
Wirtschaftlichkeit und E zienz zu erreichen. Der gegenw artige Stand der Technik
im SLA-Management begegnet Herausforderungen wie SLA-Darstellung f ur Cloud-
Dienste, gesch aftsbezogene SLA-Optimierungen, Dienste-Outsourcing und Ressourcenmanagement.
Diese Gebiete scha en zentrale und aktuelle Forschungsthemen. Das
Management von SLAs in unterschiedlichen Phasen w ahrend ihrer Laufzeit erfordert
eine daf ur entwickelte Methodik. Dadurch wird die Realisierung von Cloud SLAManagement
vereinfacht.
Ich pr asentiere ein breit gef achertes Modell im SLA-Laufzeitmanagement, das die
genannten Herausforderungen adressiert. Diese Herangehensweise erm oglicht eine automatische
Dienstemodellierung, sowie Aushandlung, Bereitstellung und Monitoring
von SLAs. W ahrend der Erstellungsphase skizziere ich, wie die Modellierungsstrukturen
verbessert und vereinfacht werden k onnen. Ein weiteres Ziel von meinem Ansatz
ist die Minimierung von Implementierungs- und Outsourcingkosten zugunsten von
Wettbewerbsf ahigkeit. In der SLA-Monitoringphase entwickle ich Strategien f ur die
Auswahl und Zuweisung von virtuellen Cloud Ressourcen in Migrationsphasen. Anschlie
end pr ufe ich mittels Monitoring eine gr o ere Zusammenstellung von SLAs, ob
die vereinbarten Fehlertoleranzen eingehalten werden.
Die vorliegende Arbeit leistet einen Beitrag zu einem Entwurf der GWDG und
deren wissenschaftlichen Communities. Die Forschung, die zu dieser Doktorarbeit
gef uhrt hat, wurde als Teil von dem SLA@SOI EU/FP7 integriertem Projekt durchgef
uhrt (contract No. 216556)
The New York Philharmonic Strike of 1973
The New York Philharmonic Strike of 1973 is a story waiting to be told. The sole volume to mention it, John Canarina\u27s The New York Philharmonic, devotes less than two pages to it. Until now, the full story has lain buried in archival documents, newspaper articles, and the memories of those who experienced it firsthand. This document represents the first comprehensive examination of this event. The research upon which it is based consists of: interviews with the New York Philharmonic members; research in the New York Philharmonic Archives; newspaper articles and reviews. The results are presented here in three interrelated narratives: a) the historical background to the tenor of labor relations between orchestral musicians and their respective managements in the United States going back more than a century, with a detailed focus upon past labor relations of the New York Philharmonic; b) a comprehensive narrative of the 1973 strike; and c) a study of the consequences of the strike for the Philharmonic with an overview of current and potentially future problems in labor relations for both the Philharmonic and rest of American symphony orchestras
Solving time-dependent PDEs with the ultraspherical spectral method
We apply the ultraspherical spectral method to solving time-dependent PDEs by
proposing two approaches to discretization based on the method of lines and
show that these approaches produce approximately same results. We analyze the
stability, the error, and the computational cost of the proposed method. In
addition, we show how adaptivity can be incorporated to offer adequate spatial
resolution efficiently. Both linear and nonlinear problems are considered. We
also explore time integration using exponential integrators with the
ultraspherical spatial discretization. Comparisons with the Chebyshev
pseudospectral method are given along the discussion and they show that the
ultraspherical spectral method is a competitive candidate for the spatial
discretization of time-dependent PDEs
FFTPL: An Analytic Placement Algorithm Using Fast Fourier Transform for Density Equalization
We propose a flat nonlinear placement algorithm FFTPL using fast Fourier
transform for density equalization. The placement instance is modeled as an
electrostatic system with the analogy of density cost to the potential energy.
A well-defined Poisson's equation is proposed for gradient and cost
computation. Our placer outperforms state-of-the-art placers with better
solution quality and efficiency
The polynomial dimensional decomposition method in a class of dynamical system with uncertainty
In this paper, polynomial dimensional decomposition (PDD) method is applied to study the dynamical model for the first time. PDD method can reserve the amplitude-frequency characteristics of the exact solution which is obtained by the Monte Carlo simulation (MCS) method except the frequency close to the resonance, the perturbations appear around the resonance frequency. All these results are shown on the two degrees of freedom (DOF) spring system with uncertainties; the dynamical characteristics of stiffness and hybrid uncertainty uncertainty are studied in seven cases respectively. The higher PDD order approximates better to the MCS results
Revealing nonclassicality beyond Gaussian states via a single marginal distribution
A standard method to obtain information on a quantum state is to measure
marginal distributions along many different axes in phase space, which forms a
basis of quantum state tomography. We theoretically propose and experimentally
demonstrate a general framework to manifest nonclassicality by observing a
single marginal distribution only, which provides a novel insight into
nonclassicality and a practical applicability to various quantum systems. Our
approach maps the 1-dim marginal distribution into a factorized 2-dim
distribution by multiplying the measured distribution or the vacuum-state
distribution along an orthogonal axis. The resulting fictitious Wigner function
becomes unphysical only for a nonclassical state, thus the negativity of the
corresponding density operator provides an evidence of nonclassicality.
Furthermore, the negativity measured this way yields a lower bound for
entanglement potential---a measure of entanglement generated using a
nonclassical state with a beam splitter setting that is a prototypical model to
produce continuous-variable (CV) entangled states. Our approach detects both
Gaussian and non-Gaussian nonclassical states in a reliable and efficient
manner. Remarkably, it works regardless of measurement axis for all
non-Gaussian states in finite-dimensional Fock space of any size, also
extending to infinite-dimensional states of experimental relevance for CV
quantum informatics. We experimentally illustrate the power of our criterion
for motional states of a trapped ion confirming their nonclassicality in a
measurement-axis independent manner. We also address an extension of our
approach combined with phase-shift operations, which leads to a stronger test
of nonclassicality, i.e. detection of genuine non-Gaussianity under a CV
measurement.Comment: 6 pages, 4 figures with Supplemental Informatio
A Novel Two-Component Response Regulator Links rpfwith Biofilm Formation and Virulence of Xanthomonasaxonopodis pv. Citri
Citrus bacterial canker caused by Xanthomonas axonopodis pv. citri is a serious disease that impacts citrus productionworldwide, and X. axonopodis pv. citri is listed as a quarantine pest in certain countries. Biofilm formation is important forthe successful development of a pathogenic relationship between various bacteria and their host(s). To understand themechanisms of biofilm formation by X. axonopodis pv. citri strain XW19, the strain was subjected to transposonmutagenesis. One mutant with a mutation in a two-component response regulator gene that was deficient in biofilmformation on a polystyrene microplate was selected for further study. The protein was designated as BfdR for biofilmformation defective regulator. BfdR from strain XW19 shares 100% amino acid sequence identity with XAC1284 of X.axonopodis pv. citri strain 306 and 30–100% identity with two-component response regulators in various pathogens andenvironmental microorganisms. The bfdR mutant strain exhibited significantly decreased biofilm formation on the leafsurfaces of Mexican lime compared with the wild type strain. The bfdR mutant was also compromised in its ability to causecanker lesions. The wild-type phenotype was restored by providing pbfdR in trans in the bfdR mutant. Our data indicatedthat BfdR did not regulate the production of virulence-related extracellular enzymes including amylase, lipase, protease, andlecithinase or the expression of hrpG, rfbC, and katE; however, BfdR controlled the expression of rpfF in XVM2 medium,which mimics cytoplasmic fluids in planta. In conclusion, biofilm formation on leaf surfaces of citrus is important for cankerdevelopment in X. axonopodis pv. citri XW19. The process is controlled by the two-component response regulator BfdR viaregulation of rpfF, which is required for the biosynthesis of a diffusible signal factor
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