A new model for gravitational potential perturbations in disks of spiral galaxies. An application to our Galaxy

We propose a new, more realistic, description of the perturbed gravitational potential of spiral galaxies, with spiral arms having Gaussian-shaped groove profiles. We investigate the stable stellar orbits in galactic disks, using the new perturbed potential. The influence of the bulge mass on the stellar orbits in the inner regions of a disk is also investigated. The new description offers the advantage of easy control of the parameters of the Gaussian profile of its potential. We find a range of values for the perturbation amplitude from 400 to 800 km^2 s^{-2} kpc^{-1} which implies a maximum ratio of the tangential force to the axisymmetric force between 3% and 6%, approximately. Good self-consistency of arm shapes is obtained between the Inner Lindblad resonance (ILR) and the 4:1 resonance. Near the 4:1 resonance the response density starts to deviate from the imposed logarithmic spiral form. This creates bifurcations that appear as short arms. Therefore the deviation from a perfect logarithmic spiral in galaxies can be understood as a natural effect of the 4:1 resonance. Beyond the 4:1 resonance we find closed orbits which have similarities with the arms observed in our Galaxy. In regions near the center, in the presence of a massive bulge, elongated stellar orbits appear naturally, without imposing any bar-shaped potential, but only extending the spiral perturbation a little inward of the ILR. This suggests that a bar is formed with a half-size around 3 kpc by a mechanism similar to that of the spiral arms. The potential energy perturbation that we adopted represents an important step in the direction of self-consistency, compared to previous sine function descriptions of the potential. Our model produces a realistic description of the spiral structure, able to explain several details that were not yet understood.Comment: 12 pag., 11 fig. Accepted for publication in A&A, 2012 December 1

The Dairy Sector of Brazil: A Country Study

Agribusiness, International Development, International Relations/Trade,

Characterization of the CBC2 readout ASIC for the CMS strip-tracker high-luminosity upgrade

The CMS Binary Chip 2 (CBC2) is a full-scale prototype ASIC developed for the front-end readout of the high-luminosity upgrade of the CMS silicon strip tracker. The 254-channel, 130 nm CMOS ASIC is designed for the binary readout of double-layer modules, and features cluster-width discrimination and coincidence logic for detecting high-PT track candidates. The chip was delivered in January 2013 and has since been bump-bonded to a dual-chip hybrid and extensively tested. The CBC2 is fully functional and working to specification: we present the result of electrical characterization of the chip, including gain, noise, threshold scan and power consumption, together with the performance of the stub finding logic. Finally we will outline the plan for future developments towards the production version

Early Identification of Violent Criminal Gang Members

Gang violence is a major problem in the United States accounting for a large fraction of homicides and other violent crime. In this paper, we study the problem of early identification of violent gang members. Our approach relies on modified centrality measures that take into account additional data of the individuals in the social network of co-arrestees which together with other arrest metadata provide a rich set of features for a classification algorithm. We show our approach obtains high precision and recall (0.89 and 0.78 respectively) in the case where the entire network is known and out-performs current approaches used by law-enforcement to the problem in the case where the network is discovered overtime by virtue of new arrests - mimicking real-world law-enforcement operations. Operational issues are also discussed as we are preparing to leverage this method in an operational environment.Comment: SIGKDD 201

Optimization of multi-domain queries on the Web

Where can I attend an interesting database workshop close to a sunny beach? Who are the strongest experts on service computing based upon their recent publication record and accepted European projects? Can I spend an April week- end in a city served by a low-cost direct flight from Milano offering a Mahler's symphony? We regard the above queries as multi-domain queries, i.e., queries that can be answered by combining knowledge from two or more domains (such as: seaside locations, flights, publications, accepted projects, conference offerings, and so on). This information is avail- able on the Web, but no general-purpose software system can accept the above queries nor compute the answer. At the most, dedicated systems support specific multi-domain compositions (e.g., Google-local locates information such as restaurants and hotels upon geographic maps). This paper presents an overall framework for multi-domain queries on the Web. We address the following problems: (a) expressing multi-domain queries with an abstract formalism, (b) separating the treatment of "search" services within the model, by highlighting their dierences from "exact" Web services, (c) explaining how the same query can be mapped to multiple "query plans", i.e., a well-dened scheduling of service invocations, possibly in parallel, which complies with their access limitations and preserves the ranking order in which search services return results; (d) introducing cross- domain joins as first-class operation within plans; (e) eval- uating the query plans against several cost metrics so as to choose the most promising one for execution. This frame- work adapts to a variety of application contexts, ranging from end-user-oriented mash-up scenarios up to complex ap- plication integration scenarios

Acute pyelonephritis during pregnancy complicated by acute respiratory distress syndrome - Two cases report

O síndrome de dificuldade respiratória aguda (SDRA) caracteriza-se por lesão pulmonar aguda e acarreta hipoxemia, infiltrados pulmonares intersticiais difusos e diminuição da compliance pulmonar. É um evento raro e na gravidez estima-se que ocorram 16-17 casos por 100.000 gravidezes. Dentro dos factores etiológicos do SDRA destacam-se: os não relacionados com a gestação (pneumonia bacteriana, pneumonite química, sépsis e choque séptico, trauma, pancreatite aguda, lesão pulmonar aguda relacionada com transfusão...), os exacerbados pela gravidez (pneumonia vírica, listeriose, pielonefrite...) e os relacionados com a gestação (edema pulmonar associado a tocólise, embolia do líquido amniótico, embolia do trofoblasto, pré-eclâmpsia, corioamnionite e endometrite). A pielonefrite aguda é uma das principaisindicações de hospitalização anteparto e acontece em cerca de 1-2% de todas as gravidezes. As alterações fisiológicas e anatómicas que ocorrem durante a gestação originam estase urinária, o que condiciona um aumento da prevalência de infecções do tracto urinário (ITU). A compressão mecânica pelo útero é a principal causa de hidroureter e hidronefrose (mais evidente à direita); o relaxamento do músculo liso induzido pela progesterona tem um papel importante no aumento da capacidade vesical e estase urinária. Por outro lado, as diferenças no pH urinário, a osmolaridade, a glicosúria e a aminoacidúria induzida pela gravidez podem facilitar o crescimento bacteriano. No entanto, há que ter em consideração outros factores de risco não-obstétricos que potenciam este quadro: antecedentes de pielonefrite, anomalias do tracto urinário (incompetência das válvulas vesico-uretrais, cálculos renais), condições médicas (diabetes mellitus, anemia de célulasfalciformes), problemas neurológicos (paralisia por lesão da medula espinhal) e baixo estatuto socioeconómico. Entre as complicações maternas e fetais associados à pielonefrite destacam-se: a anemia, a sépsis e a disfunção renal transitória. Tem sido também reportada como causa de síndrome de dificuldade respiratória aguda (SDRA), e cerca de 7% das grávidas com pielonefrite pode desenvolverinsuficiência respiratória (IR). Esta associação foi descrita pela primeira vez em 1984 por Cunningham, que considerou que as endotoxinas libertadas pela lise da parede bacteriana originaria a lesão alveolar-capilar, provocando falência respiratória. No entanto, o mecanismo exacto desta complicação ainda está por esclarecer. A morbi-mortalidade materna e fetal do SDRA é alta. Desta forma, é crucial a monitorização por equipa multidisciplinar, muitas vezes em regime de internamento na Unidade de CuidadosIntensivos(UCI). Foi realizada uma avaliação retrospectiva dos processos clínicos das duas grávidas com pielonefrite complicada com SDRA, admitidas no Centro Hospitalar do Porto (CHP), entre Janeiro de 2000 e Dezembro de 2012

Configurational temperature control for atomic and molecular systems

A new configurational temperature thermostat suitable for molecules with holonomic constraints is derived. This thermostat has a simple set of motion equations, can generate the canonical ensemble in both position and momentum space, acts homogeneously through the spatial coordinates, and does not intrinsically violate the constraints. Our new configurational thermostat is closely related to the kinetic temperature Nosé-Hoover thermostat with feedback coupled to the position variables via a term proportional to the net molecular force. We validate the thermostat by comparing equilibrium static and dynamic quantities for a fluid of n-decane molecules under configurational and kinetic temperature control. Practical aspects concerning the implementation of the new thermostat in a molecular dynamics code and the potential applications are discussed