31 research outputs found
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Foraging Responses of Black-Legged Kittiwakes to Prolonged Food-Shortages around Colonies on the Bering Sea Shelf
We hypothesized that changes in southeastern Bering Sea foraging conditions for black-legged kittiwakes (Rissa tridactyla)
have caused shifts in habitat use with direct implications for population trends. To test this, we compared at-sea
distribution, breeding performance, and nutritional stress of kittiwakes in three years (2008â2010) at two sites in the Pribilof
Islands, where the population has either declined (St. Paul) or remained stable (St. George). Foraging conditions were
assessed from changes in (1) bird diets, (2) the biomass and distribution of juvenile pollock (Theragra chalcogramma) in
2008 and 2009, and (3) eddy kinetic energy (EKE; considered to be a proxy for oceanic prey availability). In years when
biomass of juvenile pollock was low and patchily distributed in shelf regions, kittiwake diets included little or no neritic prey
and a much higher occurrence of oceanic prey (e.g. myctophids). Birds from both islands foraged on the nearby shelves, or
made substantially longer-distance trips overnight to the basin. Here, feeding was more nocturnal and crepuscular than on
the shelf, and often occurred near anticyclonic, or inside cyclonic eddies. As expected from colony location, birds from St.
Paul used neritic waters more frequently, whereas birds from St. George typically foraged in oceanic waters. Despite these
distinctive foraging patterns, there were no significant differences between colonies in chick feeding rates or fledging
success. High EKE in 2010 coincided with a 63% increase in use of the basin by birds from St. Paul compared with 2008
when EKE was low. Nonetheless, adult nutritional stress, which was relatively high across years at both colonies, peaked in
birds from St. Paul in 2010. Diminishing food resources in nearby shelf habitats may have contributed to kittiwake
population declines at St Paul, possibly driven by increased adult mortality or breeding desertion due to high foraging effort
and nutritional stress
LSST: from Science Drivers to Reference Design and Anticipated Data Products
(Abridged) We describe here the most ambitious survey currently planned in
the optical, the Large Synoptic Survey Telescope (LSST). A vast array of
science will be enabled by a single wide-deep-fast sky survey, and LSST will
have unique survey capability in the faint time domain. The LSST design is
driven by four main science themes: probing dark energy and dark matter, taking
an inventory of the Solar System, exploring the transient optical sky, and
mapping the Milky Way. LSST will be a wide-field ground-based system sited at
Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m
effective) primary mirror, a 9.6 deg field of view, and a 3.2 Gigapixel
camera. The standard observing sequence will consist of pairs of 15-second
exposures in a given field, with two such visits in each pointing in a given
night. With these repeats, the LSST system is capable of imaging about 10,000
square degrees of sky in a single filter in three nights. The typical 5
point-source depth in a single visit in will be (AB). The
project is in the construction phase and will begin regular survey operations
by 2022. The survey area will be contained within 30,000 deg with
, and will be imaged multiple times in six bands, ,
covering the wavelength range 320--1050 nm. About 90\% of the observing time
will be devoted to a deep-wide-fast survey mode which will uniformly observe a
18,000 deg region about 800 times (summed over all six bands) during the
anticipated 10 years of operations, and yield a coadded map to . The
remaining 10\% of the observing time will be allocated to projects such as a
Very Deep and Fast time domain survey. The goal is to make LSST data products,
including a relational database of about 32 trillion observations of 40 billion
objects, available to the public and scientists around the world.Comment: 57 pages, 32 color figures, version with high-resolution figures
available from https://www.lsst.org/overvie
La perception musicale chez le patient sourd implantĂ© cochlĂ©aire (intĂ©rĂȘts de l'audition rĂ©siduelle)
TOULOUSE3-BU Santé-Centrale (315552105) / SudocSudocFranceF
L'immunité des plantes : pour des cultures résistantes aux maladies
Les plantes disposent d'une immunitĂ© naturelle qui leur permet de rĂ©sister aux maladies et aux agressions parasitaires dans leur environnement. L'invention puis le dĂ©veloppement de l'agriculture ont cependant crĂ©Ă© des milieux trĂšs favorables Ă l'Ă©mergence de nouvelles maladies et au dĂ©veloppement des Ă©pidĂ©mies. Cette vulnĂ©rabilitĂ© sanitaire s'est ensuite accentuĂ©e avec l'intensification agricole, Ă partir des annĂ©es 1950, de sorte que le recours gĂ©nĂ©ralisĂ© aux pesticides de synthĂšse est devenu un pilier essentiel de la production. Ce modĂšle est dĂ©sormais remis en cause et le dĂ©veloppement d'une protection agroĂ©cologique des cultures devient une nĂ©cessitĂ©. Comprendre comment fonctionne l'immunitĂ© des plantes et dĂ©chiffrer leur arsenal de dĂ©fense face aux agressions parasitaires est essentiel pour produire des variĂ©tĂ©s rĂ©sistantes et rĂ©duire la dĂ©pendance de l'agriculture Ă la protection chimique. Mais il faut compter avec la formidable capacitĂ© d'adaptation des populations pathogĂšnes, qui conduit les chercheurs Ă imaginer des stratĂ©gies complexes pour maintenir efficace la rĂ©sistance des variĂ©tĂ©s cultivĂ©es. Les gĂšnes qui confĂšrent la rĂ©sistance aux plantes commencent Ă ĂȘtre perçus comme un bien commun Ă prĂ©server absolument. Cet ouvrage explicite les concepts fondamentaux et s'appuie sur des Ă©tudes de cas pour rĂ©aliser une synthĂšse trĂšs complĂšte des travaux en biologie, en modĂ©lisation et en sciences sociales sur ce qu'est l'immunitĂ© vĂ©gĂ©tale et sur la maniĂšre dont elle pourrait concourir Ă une agriculture respectueuse de l'environnement
Categorization of common sounds by cochlear implanted and normal hearing adults
International audienceAuditory categorization involves grouping of acoustic events along one or more shared perceptual di- mensions which can relate to both semantic and physical attributes. This process involves both high level cognitive processes (categorization) and low-level perceptual encoding of the acoustic signal, both of which are affected by the use of a cochlear implant (CI) device. The goal of this study was twofold: I) compare the categorization strategies of CI users and normal hearing listeners (NHL) II) investigate if any characteristics of the raw acoustic signal could explain the results. 16 experienced CI users and 20 NHL were tested using a Free-Sorting Task of 16 common sounds divided into 3 predefined categories of environmental, musical and vocal sounds. Multiple Correspondence Analysis (MCA) and Hierarchical Clustering based on Principal Components (HCPC) show that CI users followed a similar categorization strategy to that of NHL and were able to discriminate between the three different types of sounds. However results for CI users were more varied and showed less inter-participant agreement. Acoustic analysis also highlighted the average pitch salience and average autocorrelation peak as being important for the perception and categorization of the sounds. The results therefore show that on a broad level of categorization CI users may not have as many difficulties as previously thought in discriminating certain kinds of sound; however the perception of individual sounds remains challenging
Ratescale values of sounds as a function of time for the four groups of stimuli.
<p>Group 1: positive gain and violation of race model, group 2: positive gain and race model satisfied, group 3: positive gain and inverse violation of race model and group 4: negative gain and inverse violation of race model. Groups are described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0172480#pone.0172480.g003" target="_blank">Fig 3</a>. Note that there are differences between group 4 versus all other groups of stimuli for humans, which is not found for monkeys.</p
Multisensory gain for each stimulus, ranked by gain, for the 3 subject species.
<p>Group 1 (orange) corresponds to stimuli which induce positive gain and race model violation, group 2 (yellow) to stimuli which induce positive gain and satisfy race model, group 3 (light grey) to stimuli which induce positive gain and violate the race model inversely and group 4 (dark grey) to stimuli with negative gain and violate the race model inversely.</p
Reaction time data for monkey 1 (A), for monkey 2 (B) and for humans (C).
<p>Blue box plots correspond to auditory (A), green to visual (V) and red to auditoryâvisual (AV) stimuli. The box and horizontal bar within represent the interquartile range and the median of RT, respectively. The whiskers extend to the most extreme data point, which is no more than 1.5 times the interquartile range from the box. The notch approximates a 95% confidence interval for the median. Significance is reported using asterisks depending on the P value: * for p<0.05, ** for p<0.01 and *** for p<0.001.</p
Formula of physical parameters of sounds and images.
<p>Formula of physical parameters of sounds and images.</p
Percentage of normalized reaction time for different combinations of successive modalities.
<p>Auditory (A) N trials are plotted in the left part of the figures, visual (V) in the center and auditory-visual (AV) in the right part. N trials are sorted by N-1 trialsâ modality, with auditory on the left in blue, visual in the center in green and auditory-visual on the right in red. Once sorted, N-1 reaction times are divided by the median reaction time of all N trials for the corresponding modality. For example, for the three leftmost bars, the data was normalized by dividing by the median reaction time of all auditory trials. Bars and error bars represent respectively median and 95% confidence interval of the median. Significance is reported using asterisks depending on the P value: * for p<0.05, ** for p<0.01 and *** for p<0.001.</p