The use of gliders for oceanographic science: the data processing gap

Autonomous gliders represent a step change in the way oceanographic data can be collected and as such they are increasingly seen as valuable tools in the oceanographer’s arsenal. However, their increase in use has left a gap regarding the conversion of the signals that their sensors collect into scientifically useable data.At present the novelty of gliders means that only a few research groups within the UK are capable of processing glider data whilst the wider oceanographic community is often unaware that requesting deployment of a glider by MARS does not mean that they will be provided with fully processed and calibrated data following the deployment. This is not a failing of MARS – it is not in their remit – but it does mean that a solution is needed at the UK community level. The solution is also needed quickly given the rapidly growing glider fleet and requests to use it.To illustrate the far from trivial resources and issues needed to solve this problem at a community level, this document briefly summarises the resources and steps involved in carrying glider data through from collection to final product, for the glider owning research groups within the UK which have the capability.This report does not provide a recommendation on whether such a community facility should be the responsibility of NOC, BODC or MARS but does provide information on possible protocols and available software that could be part of a solution.This report does, however, recommend that, to support the growing use of the MARS gliders, a permanently staffed group is needed as a priority, to provide data processing and calibration necessary to allow the translation of glider missions into high impact scientific publications

Designing a Belief Function-Based Accessibility Indicator to Improve Web Browsing for Disabled People

The purpose of this study is to provide an accessibility measure of web-pages, in order to draw disabled users to the pages that have been designed to be ac-cessible to them. Our approach is based on the theory of belief functions, using data which are supplied by reports produced by automatic web content assessors that test the validity of criteria defined by the WCAG 2.0 guidelines proposed by the World Wide Web Consortium (W3C) organization. These tools detect errors with gradual degrees of certainty and their results do not always converge. For these reasons, to fuse information coming from the reports, we choose to use an information fusion framework which can take into account the uncertainty and imprecision of infor-mation as well as divergences between sources. Our accessibility indicator covers four categories of deficiencies. To validate the theoretical approach in this context, we propose an evaluation completed on a corpus of 100 most visited French news websites, and 2 evaluation tools. The results obtained illustrate the interest of our accessibility indicator

Collective nostalgia: a group-level emotion that confers unique benefits on the group

This research established collective nostalgia as a group-level emotion and ascertained the benefits it confers on the group. In Study 1, participants who reflected on a nostalgic event they had experienced together with ingroup members (collective nostalgia) evaluated the ingroup more positively and reported stronger intentions to approach (and not avoid) ingroup members than those who recalled a nostalgic event they had experienced individually (personal nostalgia), those who reflected on a lucky event they had experienced together with ingroup members (collective positive), and those who did not recall an event (no recall). In Study 2, collective (vs. personal) nostalgia strengthened behavioral intentions to support the ingroup more so than did recalling an ordinary collective (vs. personal) event. Increased collective self-esteem mediated this effect. In Study 3, collective nostalgia (compared with recall of an ordinary collective event) led participants to sacrifice money in order to punish a transgression perpetrated against an ingroup member. This effect of collective nostalgia was more pronounced when social identification was high (compared with low). Finally, in Study 4, collective nostalgia converged toward the group average (i.e., was socially shared) when participants thought of themselves in terms of their group membership. The findings underscore the viability of studying nostalgia at multiple levels of analysis and highlight the significance of collective nostalgia for understanding group-level attitudes, global action tendencies, specific behavioral intentions, and behavior

Benthic biomass size spectra in shelf and deep-sea sediments

The biomass distributions of marine benthic metazoans (meio- to macro-fauna, 1 ?g–32 mg wet weight) across three contrasting sites were investigated to test the hypothesis that allometry can consistently explain observed trends in biomass spectra. Biomass (and abundance) size spectra were determined from observations made at the Faroe–Shetland Channel (FSC) in the Northeast Atlantic (water depth 1600 m), the Fladen Ground (FG) in the North Sea (150 m), and the hypoxic Oman Margin (OM) in the Arabian Sea (500 m). Observed biomass increased with body size as a power law at FG (scaling exponent, b = 0.16) and FSC (b = 0.32), but less convincingly at OM (b = 0.12 but not significantly different from 0). A simple model was constructed to represent the same 16 metazoan size classes used for the observed spectra, all reliant on a common detrital food pool, and allowing the three key processes of ingestion, respiration and mortality to scale with body size. A micro-genetic algorithm was used to fit the model to observations at the sites. The model accurately reproduces the observed scaling without needing to include the effects of local influences such as hypoxia. Our results suggest that the size-scaling of mortality and ingestion are dominant factors determining the distribution of biomass across the meio- to macrofaunal size range in contrasting marine sediment communities. Both the observations and the model results are broadly in agreement with the "metabolic theory of ecology" in predicting a quarter power scaling of biomass across geometric body size classes

Global Strings and the Aharonov-Bohm Effect

When a fermion interacts with a global vortex or cosmic string a solenoidal "gauge" field is induced. This results in a non-trivial scattering cross-section. For scalars and non-relativistic fermions the cross-section is similar to that of Aharonov and Bohm, but with corrections. A cosmological example is compared to one in liquid He$^{3}$-A and important differences are discovered.Comment: 11 pages, DAMTP 93-5

Picture Gorge Basalt: Internal stratigraphy, eruptive patterns, and its importance for understanding Columbia River Basalt Group magmatism

The Picture Gorge Basalt (PGB) of the Columbia River Basalt Group (CRBG) has been previously thought to be limited in its eruptive volume (\u3c3000 \u3ekm3) and thought to not extend far from its type locality. At present, PGB represents only 1.1 vol% of the CRBG with a relatively limited spatial distribution of ~10,000 km2. New age data illustrate that the PGB is the earliest and longest eruptive unit compared to other main-phase CRBG formations and that some dated basaltic flows reach far (~100 km) beyond the previously mapped extent. This study focuses on extensive outcrops of basaltic lavas and dikes south of the type locality at Picture Gorge, in order to reassess the spatial distribution and eruptive volume of the PGB. Field observations coupled with geochemical data indicate that PGB lava flows and mafic dikes covered a significantly greater area than shown on the published geologic maps. We find that additional mafic dikes located farther south of the original mapped distribution have geochemical compositions and northwest-trending orientations comparable to the dikes of the Monument dike swarm. We also identify new lava flows that can be correlated where stratigraphic control is well defined toward the original mapped PGB distribution. Our analyses and correlations are facilitated by comparison of 20 major- and trace-element abundances via a principal component analysis. This statistical comparison provides a new detailed distribution of PGB with stratigraphic significance that more than doubles the total distribution of PGB lavas and dikes and brings the eruptive volume to a new minimum of at least ~4200 km3. Geochemically correlated basaltic lavas and dikes in the extended distribution of PGB represent the earlier and later sections of the internal PGB stratigraphy. This is an intriguing observation as new geochronological data suggest an eruptive hiatus of ~400 k.y. during PGB volcanic activity, which occurred from 17.23 Ma to 15.76 Ma. The geochemical identifiers used to differentiate PGB from other main-phase CRBG formations include lower TiO2 (\u3c2 \u3ewt%) concentrations, lower incompatible trace-element (i.e., La, Th, and Y) abundances, and a more pronounced enrichment in large- ion- lithophile elements (LILEs) on a primitive mantle–normalized trace-element diagram (Sun and McDonough, 1989). Geochemical characteristics of PGB are interpreted to represent a magmatic source component distinct from the other main-phase CRBG units, possibly a localized backarc-sourced mantle melt. However, this source cannot be spatially restricted as there are observed PGB lava flows and dikes extending as far east as Lake Owyhee and as far south as Hart Mountain, covering at least 15,000 km2. In context with the existing stratigraphy and the new extent of PGB lavas and dikes, these ages and coupled geochemical signatures demonstrate this mantle component was not spatially localized but rather tapped across a wide region

Dominant oceanic bacteria secure phosphate using a large extracellular buffer

The ubiquitous SAR11 and Prochlorococcus bacteria manage to maintain a sufficient supply of phosphate in phosphate-poor surface waters of the North Atlantic subtropical gyre. Furthermore, it seems that their phosphate uptake may counter-intuitively be lower in more productive tropical waters, as if their cellular demand for phosphate decreases there. By flow sorting 33P-phosphate-pulsed 32P-phosphate-chased cells, we demonstrate that both Prochlorococcus and SAR11 cells exploit an extracellular buffer of labile phosphate up to 5–40 times larger than the amount of phosphate required to replicate their chromosomes. Mathematical modelling is shown to support this conclusion. The fuller the buffer the slower the cellular uptake of phosphate, to the point that in phosphate-replete tropical waters, cells can saturate their buffer and their phosphate uptake becomes marginal. Hence, buffer stocking is a generic, growth-securing adaptation for SAR11 and Prochlorococcus bacteria, which lack internal reserves to reduce their dependency on bioavailable ambient phosphate

Leading strategies in competitive on-line prediction

We start from a simple asymptotic result for the problem of on-line regression with the quadratic loss function: the class of continuous limited-memory prediction strategies admits a "leading prediction strategy", which not only asymptotically performs at least as well as any continuous limited-memory strategy but also satisfies the property that the excess loss of any continuous limited-memory strategy is determined by how closely it imitates the leading strategy. More specifically, for any class of prediction strategies constituting a reproducing kernel Hilbert space we construct a leading strategy, in the sense that the loss of any prediction strategy whose norm is not too large is determined by how closely it imitates the leading strategy. This result is extended to the loss functions given by Bregman divergences and by strictly proper scoring rules.Comment: 20 pages; a conference version is to appear in the ALT'2006 proceeding

Heavy Flavor Enhancement as a Signal of Color Deconfinement

We argue that the color deconfinement in heavy ion collisions may lead to enhanced production of hadrons with open heavy flavor (charm or bottom). We estimate the upper bound of this enhancement.Comment: 7 pages, LaTeX, 3 PS-figure