A GPU-based hyperbolic SVD algorithm

A one-sided Jacobi hyperbolic singular value decomposition (HSVD) algorithm, using a massively parallel graphics processing unit (GPU), is developed. The algorithm also serves as the final stage of solving a symmetric indefinite eigenvalue problem. Numerical testing demonstrates the gains in speed and accuracy over sequential and MPI-parallelized variants of similar Jacobi-type HSVD algorithms. Finally, possibilities of hybrid CPU--GPU parallelism are discussed.Comment: Accepted for publication in BIT Numerical Mathematic

Creation of collective many-body states and single photons from two-dimensional Rydberg lattice gases

The creation of collective many-body quantum states from a two-dimensional lattice gas of atoms is studied. Our approach relies on the van-der-Waals interaction that is present between alkali metal atoms when laser excited to high-lying Rydberg s-states. We focus on a regime in which the laser driving is strong compared to the interaction between Rydberg atoms. Here energetically low-lying many-particle states can be calculated approximately from a quadratic Hamiltonian. The potential usefulness of these states as a resource for the creation of deterministic single-photon sources is illustrated. The properties of these photon states are determined from the interplay between the particular geometry of the lattice and the interatomic spacing.Comment: 12 pages, 8 figure

On the interactions of lipids and proteins in the red blood cell membrane

The effects of temperature and of the action of a purified phospholipase C enzyme preparation on human red blood cell membranes has been investigated by chemical analyses, circular dichroism, and proton magnetic resonance measurements. The results indicate that a substantial fraction of the phospholipids and the proteins of the membranes can change structure independently of one another, suggesting a mosaic pattern for the organization of the lipids and proteins in membranes

Inverse moment problem for elementary co-adjoint orbits

We give a solution to the inverse moment problem for a certain class of Hessenberg and symmetric matrices related to integrable lattices of Toda type.Comment: 13 page

Trick or treat: the effect of placebo on the power of pharmacogenetic association studies

The genetic mapping of drug-response traits is often characterised by a poor signal-to-noise ratio that is placebo related and which distinguishes pharmacogenetic association studies from classical case-control studies for disease susceptibility. The goal of this study was to evaluate the statistical power of candidate gene association studies under different pharmacogenetic scenarios, with special emphasis on the placebo effect. Genotype/phenotype data were simulated, mimicking samples from clinical trials, and response to the drug was modelled as a binary trait. Association was evaluated by a logistic regression model. Statistical power was estimated as a function of the number of single nucleotide polymorphisms (SNPs) genotyped, the frequency of the placebo 'response', the genotype relative risk (GRR) of the response polymorphism, the strategy for selecting SNPs for genotyping, the number of individuals in the trial and the ratio of placebo-treated to drug-treated patients. We show that: (i) the placebo 'response' strongly affects the statistical power of association studies--even a highly penetrant drug-response allele requires at least a 500-patient trial in order to reach 80 per cent power, several-fold more than the value estimated by standard tools that are not calibrated to pharmacogenetics; (ii) the power of a pharmacogenetic association study depends primarily on the penetrance of the response genotype and, when this penetrance is fixed, power decreases for larger placebo effects; (iii) power is dramatically increased when adding markers; (iv) an optimal study design includes a similar number of placebo- and drug-treated patients; and (v) in this setting, straightforward haplotype analysis does not seem to have an advantage over single marker analysis

L’ADAPTATION POSITIVE DES FAMILLES LATINOS AVEC UN ENFANT AYANT UNE DÉFICIENCE INTELLECTUELLE: UNE PREMIÈRE VUE DE LA THÉORIE DE L’ADAPTATION POSITIVE

Historically, research on disability and family dynamics drew from Psychology and Medicine. Consequently, eugenics models, grief theory, and other largely decontextualized frameworks of stress and coping were used to explain families of children with disabilities. This is a report of an initial test of a set of ideas the Singer research team has combined in order to explore the cognitive and problem-solving approaches of families of children with disabilities. Our purpose is to propose a contextualized theory for explaining how cultural diversity has an impact on positive adaptation to a child’s disability. This theory addresses the following: 1) attachment; 2) internal and external cultural resistance to stigmas about disability; and 3) perceived informal (family/friends) and formal (professionals) sources of support for positive views about disability and parenting. Sampling Latino families demonstrated how cultural contexts demonstrate a different flavour from majority culture interpretations of these cognitive terms of our proposed theory. Transcripts of the interviews were coded using grounded theory analysis, specifically, the constant comparative method. We discuss the goodness of fit for themes emerging from the coding process with the proposed theory terms. Results confirm attachment, social supports, and cultural resistance as terms for future development of this proposed theory. Keywords: Disability and parenting, positive adaptation, Latinos and disability, culture and disabilityÀ travers l’histoire, la recherche sur les handicapés et les relations intrafamiliales utilisait comme sources la psychologie et la médicine. Par conséquent, les modèles de l’eugénisme, les théories sur le deuil, et d’autres cadres analytiques sur le stress et les stratégies d’adaptation, plutôt décontextualisés, étaient utilisés afin d’expliquer aux autres comment fonctionnaient les familles avec un enfant handicapé. Ceci est un reportage sur un test initial d’un ensemble d’idées qu’a combiné l’équipe de recherche Singer afin d’aborder les approches cognitives et méthodes actives des familles des enfants handicapés. Nous proposons une théorie contextualisée afin d’expliquer comment la diversité culturelle aurait un effet sur l’adaptation positive de la famille face à l’handicap de leur enfant. Cette théorie aborde les idées suivantes : 1) l’attachement; 2) les résistances culturelles internes et externes aux stigmates sur l’handicap; et 3) les sources d’information sur l’handicap et le parentage liées à l’adaptation positive perçues comme informelles (famille/amis) et formelles (les professionnels). En utilisant un échantillon de familles Latinos, nous démontrons comment les contextes culturels démontrent des interprétations différentes des termes cognitifs de notre théorie, et non l’interprétation de la culture majoritaire. Les transcriptions des interviews étaient codées selon la théorie ancrée, plus spécifiquement la méthode de la comparaison constante. Nous discutons la concordance des thèmes venus via le processus d’encodage avec les termes clés de la nouvelle théorie proposée. Les résultats de cette recherche confirment que l’attachement, le soutien social, et la résistance culturelle seront des termes clés dans le développement de cette théorie proposée. Mots clés : Handicap et parentage, Adaptation positive, Latinos et handicap, culture et handica

Rare charm meson decays D->Pl^+l^- and c->ul^+l^- in SM and MSSM

We study the nine possible rare charm meson decays D->Pl^+l^- (P=pi,K,eta,eta') using the Heavy Meson Chiral Lagrangians and find them to be dominated by the long distance contributions. The decay D^+ -> pi^+l^+l^- with the branching ratio 1*10^(-6) is expected to have the best chances for an early experimental discovery. The short distance contribution in the five Cabibbo suppressed channels arises via the c->ul^+l^- transition; we find that this contribution is detectable only in the D->pi l^+l^- decay, where it dominates the differential spectrum at high-q^2. The general Minimal Supersymmetric Standard Model can enhance the c->ul^+l^- rate by up to an order of magnitude; its effect on the D->Pl^+l^- rates is small since the c->ul^+l^- enhancement is sizable in low-q^2 region, which is inhibited in the hadronic decay.Comment: 17 page

Novel Modifications of Parallel Jacobi Algorithms

We describe two main classes of one-sided trigonometric and hyperbolic Jacobi-type algorithms for computing eigenvalues and eigenvectors of Hermitian matrices. These types of algorithms exhibit significant advantages over many other eigenvalue algorithms. If the matrices permit, both types of algorithms compute the eigenvalues and eigenvectors with high relative accuracy. We present novel parallelization techniques for both trigonometric and hyperbolic classes of algorithms, as well as some new ideas on how pivoting in each cycle of the algorithm can improve the speed of the parallel one-sided algorithms. These parallelization approaches are applicable to both distributed-memory and shared-memory machines. The numerical testing performed indicates that the hyperbolic algorithms may be superior to the trigonometric ones, although, in theory, the latter seem more natural.Comment: Accepted for publication in Numerical Algorithm

Storm time duskside equatorial current and its closure path

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/101862/1/jgra50512.pd