Vertical distribution of fish larvae in the Canaries-African coastal transition zone, in summer

13 pages, 6 figures, 2 tables.-- Printed version published Jul 2006.This study reports the vertical distribution of fish larvae during the 1999 summer upwelling season in the Canaries-African Coastal Transition Zone (the Canaries-ACTZ). The transition between the African coastal upwelling and the typical subtropical offshore conditions is a region of intense mesoscale activity that supports a larval fish population dominated by African neritic species. During the study, the thermal stratification extended almost to the surface everywhere, and the surface mixed layer was typically shallow or non-existent. Upwelling occurred on the African shelf in a limited coastal sub-area of our sampling. The vertical distributions of the entire larval fish population, as well as of individual species, were independent of the seasonal thermocline. Fish larvae and mesozooplankton were concentrated at intermediate depths regardless of the thermocline position, probably because of its weak signature and spatial and temporal variability. Day/night vertical distributions suggest that some species did not perform diel vertical migration (DVM), whereas others showed either type I DVM or type II DVM. The opposing DVM patterns of different species compensate for each other resulting in no net DVM for the larval fish population as a whole.Fieldwork was carried out as part of the CANIGO project, funded by the EU, and of the "Pelagic (EU-CICYT 1FD97-1084)" project from the Spanish Ministry of Education and the European Union

Towards a realistic interpretation of quantum mechanics providing a model of the physical world

It is argued that a realistic interpretation of quantum mechanics is possible and useful. Current interpretations, from Copenhagen to many worlds are critically revisited. The difficulties for intuitive models of quantum physics are pointed out and possible solutions proposed. In particular the existence of discrete states, the quantum jumps, the alleged lack of objective properties, measurement theory, the probabilistic character of quantum physics, the wave-particle du- ality and the Bell inequalities are analyzed. The sketch of a realistic picture of the quantum world is presented. It rests upon the assump- tion that quantum mechanics is a stochastic theory whose randomness derives from the existence of vacuum fields. They correspond to the vacuum fluctuations of quantum field theory, but taken as real rather than virtual.Comment: 43 pages, paper throughout revised and somewhat enlarged, sections on the Bell inequalities and on the sketch of a picture of the quantum world rewritten, new references adde

Adequacy and quality of abdominal echographies requested by primary care professionals

<p>Abstract</p> <p>Background</p> <p>The value of abdominal echography in primary care is great because it is innocuous, inexpensive, easy to perform and provides a great deal of information making this the first examination to be requested in cases of probable abdominal disease. <b>However, too many abdominal echographies are probably requested overcrowding the Departments of Radiodiagnosis with not always justified petitions or with repetition of tests based on little clinical criteria</b>.</p> <p>Methods/Design</p> <p><b>The aim of the study is </b>to evaluate the adequacy and quality of abdominal echographies requested by primary care physicians in the Maresme County (North of Barcelona), develop guidelines for indicating echographies and reevaluate this adequacy after implementing these guidelines.</p> <p>We will perform a two-phase study: the first descriptive, and retrospective evaluating the adequacy and quality of petitions for abdominal echographies, and in the second phase we will evaluate the impact of recommendations for indicating abdominal echographies for PC physicians on the adequacy and quality of echography petitions thereafter.</p> <p><b>This study will be carried out in 10 primary care centres </b>in the Maresme (Barcelona).</p> <p>1067 abdominal echographies requested by primary care physicians from the above mentioned centres from January 2007 to April 2010 and referred to the Department of Radiology and the same number of applications after the intervention.</p> <p>All the petitions for abdominal echographies requested will be analysed and the clinical histories will be obtained to determine demographic variables, the reason for the visit and for the echography petition and diagnostic orientation, clinical and echographic data, evaluation of the echographies according to the quality and variables characterising the professionals requesting the echographies including: age, sex, laboral situation, length of time in work post, formation, etc.</p> <p>To achieve a consensus of the adequacy of abdominal echography, a work group including gastroenterologists, radiologists and general practitioners will be created following the nominal group. This will allow the design of guidelines for the indication of abdominal echography and posterior evaluation of their impact among physicians by diffusion and posterior reevaluation of the adequacy of the petitions.</p

Elevated visual dependency in young adults after chemotherapy in childhood

Chemotherapy in childhood can result in long-term neurophysiological side-effects, which could extend to visual processing, specifically the degree to which a person relies on vision to determine vertical and horizontal (visual dependency). We investigated whether adults treated with chemotherapy in childhood experience elevated visual dependency compared to controls and whether any difference is associated with the age at which subjects were treated. Visual dependency was measured in 23 subjects (mean age 25.3 years) treated in childhood with chemotherapy (CTS) for malignant, solid, non-CNS tumors. We also stratified CTS into two groups: those treated before 12 years of age and those treated from 12 years of age and older. Results were compared to 25 healthy, age-matched controls. The subjective visual horizontal (SVH) and vertical (SVV) orientations was recorded by having subjects position an illuminated rod to their perceived horizontal and vertical with and without a surrounding frame tilted clockwise and counter-clockwise 20° from vertical. There was no significant difference in rod accuracy between any CTS groups and controls without a frame. However, when assessing visual dependency using a frame, CTS in general (p = 0.006) and especially CTS treated before 12 years of age (p = 0.001) tilted the rod significantly further in the direction of the frame compared to controls. Our findings suggest that chemotherapy treatment before 12 years of age is associated with elevated visual dependency compared to controls, implying a visual bias during spatial activities. Clinicians should be aware of symptoms such as visual vertigo in adults treated with chemotherapy in childhood

Atlantic Leatherback Migratory Paths and Temporary Residence Areas

BACKGROUND: Sea turtles are long-distance migrants with considerable behavioural plasticity in terms of migratory patterns, habitat use and foraging sites within and among populations. However, for the most widely migrating turtle, the leatherback turtle Dermochelys coriacea, studies combining data from individuals of different populations are uncommon. Such studies are however critical to better understand intra- and inter-population variability and take it into account in the implementation of conservation strategies of this critically endangered species. Here, we investigated the movements and diving behaviour of 16 Atlantic leatherback turtles from three different nesting sites and one foraging site during their post-breeding migration to assess the potential determinants of intra- and inter-population variability in migratory patterns. METHODOLOGY/PRINCIPAL FINDINGS: Using satellite-derived behavioural and oceanographic data, we show that turtles used Temporary Residence Areas (TRAs) distributed all around the Atlantic Ocean: 9 in the neritic domain and 13 in the oceanic domain. These TRAs did not share a common oceanographic determinant but on the contrary were associated with mesoscale surface oceanographic features of different types (i.e., altimetric features and/or surface chlorophyll a concentration). Conversely, turtles exhibited relatively similar horizontal and vertical behaviours when in TRAs (i.e., slow swimming velocity/sinuous path/shallow dives) suggesting foraging activity in these productive regions. Migratory paths and TRAs distribution showed interesting similarities with the trajectories of passive satellite-tracked drifters, suggesting that the general dispersion pattern of adults from the nesting sites may reflect the extent of passive dispersion initially experienced by hatchlings. CONCLUSIONS/SIGNIFICANCE: Intra- and inter-population behavioural variability may therefore be linked with initial hatchling drift scenarios and be highly influenced by environmental conditions. This high degree of behavioural plasticity in Atlantic leatherback turtles makes species-targeted conservation strategies challenging and stresses the need for a larger dataset (>100 individuals) for providing general recommendations in terms of conservation