Prioritized Metric Structures and Embedding

Metric data structures (distance oracles, distance labeling schemes, routing schemes) and low-distortion embeddings provide a powerful algorithmic methodology, which has been successfully applied for approximation algorithms \cite{llr}, online algorithms \cite{BBMN11}, distributed algorithms \cite{KKMPT12} and for computing sparsifiers \cite{ST04}. However, this methodology appears to have a limitation: the worst-case performance inherently depends on the cardinality of the metric, and one could not specify in advance which vertices/points should enjoy a better service (i.e., stretch/distortion, label size/dimension) than that given by the worst-case guarantee. In this paper we alleviate this limitation by devising a suit of {\em prioritized} metric data structures and embeddings. We show that given a priority ranking $(x_1,x_2,\ldots,x_n)$ of the graph vertices (respectively, metric points) one can devise a metric data structure (respectively, embedding) in which the stretch (resp., distortion) incurred by any pair containing a vertex $x_j$ will depend on the rank $j$ of the vertex. We also show that other important parameters, such as the label size and (in some sense) the dimension, may depend only on $j$. In some of our metric data structures (resp., embeddings) we achieve both prioritized stretch (resp., distortion) and label size (resp., dimension) {\em simultaneously}. The worst-case performance of our metric data structures and embeddings is typically asymptotically no worse than of their non-prioritized counterparts.Comment: To appear at STOC 201

The Visibility of Galactic Bars and Spiral Structure At High Redshifts

We investigate the visibility of galactic bars and spiral structure in the distant Universe by artificially redshifting 101 B-band CCD images of local spiral galaxies from the Ohio State University Bright Spiral Galaxy Survey. Our artificially redshifted images correspond to Hubble Space Telescope I-band observations of the local galaxy sample seen at z=0.7, with integration times matching those of both the very deep Northern Hubble Deep Field data, and the much shallower Flanking Field observations. The expected visibility of galactic bars is probed in two ways: (1) using traditional visual classification, and (2) by charting the changing shape of the galaxy distribution in "Hubble space", a quantitative two-parameter description of galactic structure that maps closely on to Hubble's original tuning fork. Both analyses suggest that over 2/3 of strongly barred luminous local spirals i.e. objects classified as SB in the Third Reference Catalog) would still be classified as strongly barred at z=0.7 in the Hubble Deep Field data. Under the same conditions, most weakly barred spirals (classified SAB in the Third Reference Catalog) would be classified as regular spirals. The corresponding visibility of spiral structure is assessed visually, by comparing luminosity classifications for the artificially redshifted sample with the corresponding luminosity classifications from the Revised Shapley Ames Catalog. We find that for exposures times similar to that of the Hubble Deep Field spiral structure should be detectable in most luminous low-inclination spiral galaxies at z=0.7 in which it is present. [ABRIDGED]Comment: Accepted for publication in The Astronomical Journa

On the analysis of tuberculosis studies with intermittent missing sputum data

In randomized studies evaluating treatments for tuberculosis (TB), individuals are scheduled to be routinely evaluated for the presence of TB using sputum cultures. One important endpoint in such studies is the time of culture conversion, the first visit at which a patient’s sputum culture is negative and remains negative. This article addresses how to draw inference about treatment effects when sputum cultures are intermittently missing on some patients. We discuss inference under a novel benchmark assumption and under a class of assumptions indexed by a treatment-specific sensitivity parameter that quantify departures from the benchmark assumption. We motivate and illustrate our approach using data from a randomized trial comparing the effectiveness of two treatments for adult TB patients in Brazil.Fil: Scharfstein, Daniel. University Johns Hopkins; Estados UnidosFil: Rotnitzky, Andrea Gloria. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Torcuato Di Tella. Departamento de Economía; ArgentinaFil: Abraham, Maria. Statistics Collaborative; Estados UnidosFil: McDermott, Aidan. University Johns Hopkins; Estados UnidosFil: Chaisson, Richard. University Johns Hopkins; Estados UnidosFil: Geiter, Lawrence. Otsuka Novel Products; Estados Unido

Factors affecting the sensitivity to insulin of diaphragm and adipose tissue in obese mice and their lean littermates

Imperial Users onl

Robobo: la siguiente generación de robot educativo

[Resumen] Las carreras universitarias de informática e ingeniería han estado utilizando robots móviles en diferentes asignaturas desde hace mucho tiempo. Hasta el momento, debido principalmente a limitaciones económicas, estos robots educativos han sido bastante simples en términos tecnológicos. Esto no era un gran problema porque la robótica no se consideraba un mercado real en la industria, por lo que los robots se usaban en las clases como prototipos, sin una expectativa de aplicación a la realidad. Pero como todos sabemos, la situación actual, y el futuro cercano, hacen que la robótica sea un mercado clave para los ingenieros y los informáticos que se forman en las universidades. Como consecuencia, los robots utilizados en las aulas universitarias deben ser actualizados para adecuarlos a la realidad tecnológica que se maneja en el mundo industrial. Este artículo presenta Robobo, un robot móvil educativo de bajo costo desarrollado en la Universidade da Coruña. Robobo combina una base con ruedas simple con un teléfono inteligente, que proporciona la última tecnología al robot. Con Robobo, los estudiantes pueden desarrollar sus propios proyectos usando cámaras, micrófonos o pantallas de alta resolución, acercando la enseñanza universitaria al mercado real que encontrarán cuando finalicen sus estudios.[Abstract] Computer science and engineering majors have been using mobile robots in different subjects for a long time. So far, due primarily to economic constraints, these educational robots have been quite simple in technological terms. This was not a big problem because robotics was not considered a real market in the industry, so robots were used in classes as prototypes, without an expectation of application to reality. But as we all know, the current situation, and the near future, make robotics a key market for engineers and IT graduates in universities. As a consequence, the robots used in the university classrooms must be updated to adapt them to the technological reality that is handled in the industrial world. This article presents Robobo, a low cost educational mobile robot developed at the University of Coruña. Robobo combines a simple wheeled base with a smartphone, which provides the latest technology to the robot. With Robobo, students can develop their own projects using cameras, microphones or highresolution displays, bringing university education closer to the real market they will find when they finish their studies

Clustering of Very Red Galaxies in the Las Campanas IR Survey

We report results from the first 1000 square arc-minutes of the Las Campanas IR survey. We have imaged 1 square degree of high latitude sky in six distinct fields to a 5-sigma H-band depth of 20.5 (Vega). Optical imaging in the V,R,I,and z' bands allow us to select color subsets and photometric-redshift-defined shells. We show that the angular clustering of faint red galaxies (18 3) is an order of magnitude stronger than that of the complete H-selected field sample. We employ three approaches to estimate $n(z)$ in order to invert w(theta) to derive r_0. We find that our n(z) is well described by a Gaussian with = 1.2, sigma(z) = 0.15. From this we derive a value for r_0 of 7 (+2,-1) co-moving H^{-1} Mpc at = 1.2. This is a factor of ~ 2 larger than the clustering length for Lyman break galaxies and is similar to the expectation for early type galaxies at this epoch.Comment: 5 pages, 2 figures, 1 table. To appear in proceedings of the ESO/ECF/STScI workshop "Deep Fields" held in Garching, Germany, 9-12 October 200

Evidence for Evolving Spheroidals in the Hubble Deep Fields North and South

We investigate the dispersion in the internal colours of faint spheroidals in the HDFs North and South. We find that a remarkably large fraction ~30% of the morphologically classified spheroidals with I<24 mag show strong variations in internal colour, which we take as evidence for recent episodes of star-formation. In most cases these colour variations manifest themselves via the presence of blue cores, an effect of opposite sign to that expected from metallicity gradients. Examining similarly-selected ellipticals in five rich clusters with 0.37<z<0.83 we find a significant lower dispersion in their internal colours. This suggests that the colour inhomogeneities have a strong environmental dependence being weakest in dense environments where spheroidal formation was presumably accelerated at early times. We use the trends defined by the cluster sample to define an empirical model based on a high-redshift of formation and estimate that at z~1 about half the field spheroidals must be undergoing recent episodes of star-formation. Using spectral synthesis models, we construct the time dependence of the density of star-formation. Although the samples are currently small, we find evidence for an increase in $\rho_{SFR}$ between z=0 to z=1. We discuss the implications of this rise in the context of that observed in the similar rise in the abundance of galaxies with irregular morphology. Regardless of whether there is a connection our results provide strong evidence for the continued formation of field spheroidals over 0<z<1

Genetic and antigenic characterisation of serotype A FMD viruses from East Africa to select new vaccine strains

Vaccine strain selection for emerging foot-and-mouth disease virus (FMDV) outbreaks in enzootic countries can be addressed through antigenic and genetic characterisation of recently circulating viruses. A total of 56 serotype A FMDVs isolated between 1998 and 2012, from Central, East and North African countries were characterised antigenically by virus neutralisation test using antisera to three existing and four candidate vaccine strains and, genetically by characterising the full capsid sequence data. A Bayesian analysis of the capsid sequence data revealed the viruses to be of either African or Asian topotypes with subdivision of the African topotype viruses into four genotypes (Genotypes I, II, IV and VII). The existing vaccine strains were found to be least cross-reactive (good matches observed for only 5.4–46.4% of the sampled viruses). Three bovine antisera, raised against A-EA-2007, A-EA-1981 and A-EA-1984 viruses, exhibited broad cross-neutralisation, towards more than 85% of the circulating viruses. Of the three vaccines, A-EA-2007 was the best showing more than 90% in-vitro cross-protection, as well as being the most recent amongst the vaccine strains used in this study. It therefore appears antigenically suitable as a vaccine strain to be used in the region in FMD control programmes

Increased risk of depression in non-depressed HIV infected men with sleep disturbance: Prospective findings from the Multicenter AIDS Cohort Study.

ObjectiveSleep disturbance is a known risk factor for depression, but it is not known whether sleep disturbance contributes to greater risk of depression in those infected with human immunodeficiency virus (HIV+) as compared to those uninfected with HIV (HIV-).MethodsUsing data from the Multicenter AIDS Cohort Study, a population-based prospective study of men who have sex with men (MSM), self-reported sleep disturbance (&gt;2 weeks) and depressive symptoms (Clinical Epidemiologic Scale for Depression, CES-D) were assessed every 6 months over 12 years of follow-up. Adjusted mixed effects logistic regression analyses tested whether sleep disturbance predicted depression (CES-D ≥ 16) at the immediate subsequent visit, and so on over 12 years, in non-depressed HIV+(N = 1054; 9556 person-visits) and non-depressed HIV- (N = 1217; 12,680 person-visits). In HIV+ vs. HIV- MSM, linearly estimated average incidence of depression and normalized cumulative rate of depression over 12 years were compared.ResultsIn the HIV+ MSM, sleep disturbance was associated with a significant increase in depression 6 months later (OR = 1.6; 95% CI, 1.30, 1.96), which was significantly greater (P &lt; .05) than in HIV- MSM (OR = 1.16; 95% CI, 0.94, 1.44). HIV status and sleep disturbance interacted (P &lt; .001), such that incidence of depression and normalized cumulative rate of depression were greater in HIV+ with sleep disturbance than in HIV+ without sleep disturbance and HIV- groups (all P's &lt; 0.001).ConclusionsHIV+ persons who report sleep disturbance represent a high risk group to be monitored for depression, and possibly targeted for insomnia treatment to prevent depression. FUND: National Institute of Allergy and Infectious Diseases

Determination of two-body potentials from n-body spectra

We show how the two-body potential may be uniquely determined from n-body spectra where the hypercentral approximation is valid. We illustrate this by considering an harmonic oscillator potential which has been altered by changing the energy or normalisation constant of the ground state of the n-body system and finding how this modifies the two-body potential. It is shown that with increasing number of particles the spectrum must be known more precisely to obtain the two-body potential to the same degree of accuracy.Comment: 13 pages of text (LATEX), 3 figures (not included, available from authors), NIKHEF-93-P