Seasonal variation of the three-dimensional mean circulation over the Scotian Shelf

The seasonal-mean circulation over the Scotian Shelf is studied numerically by computing mean and tidal current fields for winter, spring, and summer using a three-dimensional nonlinear diagnostic model. The mean current fields are forced by seasonal-mean baroclinic pressure gradients, tidal rectification, uniform wind stresses, and associated barotropic pressure gradients. A historical hydrographic database is used to determine the climatological mean baroclinic forcing. Upstream open boundary conditions are estimated from the density fields to give no normal geostrophic bottom flow and are specified as either along-boundary elevation gradients or depth-integrated normal velocities. The numerical solutions for nominal bimonthly periods (January–February, April–May, and July–August) reveal the dominant southwestward nearshore and shelf-break flows of relatively cool and fresh shelf water from the Gulf of St. Lawrence and Newfoundland Shelf, with speeds up to about 20 cm/s. The seasonal intensification of the southwestward flows is reproduced by the model, with the transport increasing from 0.3 Sv in summer to 0.9 Sv in winter on the inner Halifax section. There are also pronounced topographic-scale influences of submarine banks, basins, and cross-shelf channels on the circulation, such as anticyclonic gyres over banks and cyclonic gyres over basins. Baroclinicity is the dominant forcing throughout the domain, but tidal rectification is comparable on the southwestern Scotian Shelf (e.g., about 0.2 Sv recirculating transport around Browns Bank for all the periods). The mean wind stress generates offshore surface drift in winter. The solutions are in approximate agreement with observed currents and transports over the Scotian Shelf, although there are local discrepancies

Resonance Production in STAR

The recent results from resonance production in central Au+Au and p+p collisions at $\sqrt{s_{\rm NN}} =$ 200 GeV from the STAR experiment at RHIC are presented and discussed.Comment: 7 pages, proceedings 19th Winter Workshop on Nuclear Dynamics, Breckenridge, Colorado, USA, February 8-15, 200

System size dependence of strangeness production at 158 AGeV

Strange particle production in A+A interactions at 158 AGeV is studied by the CERN experiment NA49 as a function of system size and collision geometry. Yields of charged kaons, phi and Lambda are measured and compared to those of pions in central C+C, Si+Si and centrality-selected Pb+Pb reactions. An overall increase of relative strangeness production with the size of the system is observed which does not scale with the number of participants. Arguing that rescattering of secondaries plays a minor role in small systems the observed strangeness enhancement can be related to the space-time density of the primary nucleon-nucleon collisions.Comment: 5 pages, 3 figures, Presented at Quark Matter 2002, Nantes, Franc

The multisensory attentional consequences of tool use : a functional magnetic resonance imaging study

Background: Tool use in humans requires that multisensory information is integrated across different locations, from objects seen to be distant from the hand, but felt indirectly at the hand via the tool. We tested the hypothesis that using a simple tool to perceive vibrotactile stimuli results in the enhanced processing of visual stimuli presented at the distal, functional part of the tool. Such a finding would be consistent with a shift of spatial attention to the location where the tool is used. Methodology/Principal Findings: We tested this hypothesis by scanning healthy human participants’ brains using functional magnetic resonance imaging, while they used a simple tool to discriminate between target vibrations, accompanied by congruent or incongruent visual distractors, on the same or opposite side to the tool. The attentional hypothesis was supported: BOLD response in occipital cortex, particularly in the right hemisphere lingual gyrus, varied significantly as a function of tool position, increasing contralaterally, and decreasing ipsilaterally to the tool. Furthermore, these modulations occurred despite the fact that participants were repeatedly instructed to ignore the visual stimuli, to respond only to the vibrotactile stimuli, and to maintain visual fixation centrally. In addition, the magnitude of multisensory (visual-vibrotactile) interactions in participants’ behavioural responses significantly predicted the BOLD response in occipital cortical areas that were also modulated as a function of both visual stimulus position and tool position. Conclusions/Significance: These results show that using a simple tool to locate and to perceive vibrotactile stimuli is accompanied by a shift of spatial attention to the location where the functional part of the tool is used, resulting in enhanced processing of visual stimuli at that location, and decreased processing at other locations. This was most clearly observed in the right hemisphere lingual gyrus. Such modulations of visual processing may reflect the functional importance of visuospatial information during human tool use

How the Cervical Microbiota Contributes to Cervical Cancer Risk in Sub-Saharan Africa

Despite ongoing efforts, sub-Saharan Africa faces a higher cervical cancer burden than anywhere else in the world. Besides HPV infection, definitive factors of cervical cancer are still unclear. Particular states of the cervicovaginal microbiota and viral infections are associated with increased cervical cancer risk. Notably, HIV infection, which is prevalent in sub-Saharan Africa, greatly increases risk of cervicovaginal dysbiosis and cervical cancer. To better understand and address cervical cancer in sub-Saharan Africa, a better knowledge of the regional cervicovaginal microbiome is required This review establishes current knowledge of HPV, HIV, cervicovaginal infections, and the cervicovaginal microbiota in sub-Saharan Africa. Because population statistics are not available for the region, estimates are derived from smaller cohort studies. Microbiota associated with cervical inflammation have been found to be especially prevalent in sub-Saharan Africa, and to associate with increased cervical cancer risk. In addition to high prevalence and diversity of HIV and HPV, intracellular bacterial infections such as Chlamydia, Gonorrhea, and Mycoplasma hominis are much more common than in regions with a low burden of cervical cancer. This suggests the prevalence of cervical cancer in sub-Saharan Africa may be partially attributed to increased cervical inflammation resulting from higher likelihood of cervical infection and/or microbial dysbiosis

Report of the panel on volcanology, section 4

Two primary goals are identified as focal to NASA's research efforts in volcanology during the 1990s: to understand the eruption of lavas, gases, and aerosols from volcanoes, the dispersal of these materials on the Earth's surface and through the atmosphere, and the effects of these eruptions on the climate and environment; and to understand the physical processes that lead to the initiation of volcanic activity, that influence the styles of volcanic eruptions, and that dictate the morphology and evolution of volcanic landforms. Strategy and data requirements as well as research efforts are discussed

Exploring Photometric Redshifts as an Optimization Problem: An Ensemble MCMC and Simulated Annealing-Driven Template-Fitting Approach

Using a grid of $\sim 2$ million elements ($\Delta z = 0.005$) adapted from COSMOS photometric redshift (photo-z) searches, we investigate the general properties of template-based photo-z likelihood surfaces. We find these surfaces are filled with numerous local minima and large degeneracies that generally confound rapid but "greedy" optimization schemes, even with additional stochastic sampling methods. In order to robustly and efficiently explore these surfaces, we develop BAD-Z [Brisk Annealing-Driven Redshifts (Z)], which combines ensemble Markov Chain Monte Carlo (MCMC) sampling with simulated annealing to sample arbitrarily large, pre-generated grids in approximately constant time. Using a mock catalog of 384,662 objects, we show BAD-Z samples $\sim 40$ times more efficiently compared to a brute-force counterpart while maintaining similar levels of accuracy. Our results represent first steps toward designing template-fitting photo-z approaches limited mainly by memory constraints rather than computation time.Comment: 14 pages, 8 figures; submitted to MNRAS; comments welcom