Search results for "Gamma"
showing 10 items of 3093 documents
"Table 5" of "Measurement of differential Z / gamma* + jet + X cross sections in p anti-p collisions at s**(1/2) = 1.96-TeV"
2008
Integrated cross section.. The second DSYS error is from the muon identification and the third from the luminosity measurement.
"Table 18" of "Measurement of the production cross section for Z/gamma* in association with jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS d…
2014
Measured normalized inclusive jet differential cross section 1/sigma_DY dsigma/dy for the electron channel and the muon channel in the individual lepton fiducial regions and uncorrected for QED effects.
"Table 19" of "Measurement of the production cross section for Z/gamma* in association with jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS d…
2014
Measured normalized leading jet differential cross section 1/sigma_DY dsigma/dy for the electron channel and the muon channel in the individual lepton fiducial regions and uncorrected for QED effects.
Zvaigžņotā Debess: 2009, Vasara (204)
2009
Contents: E.Conners. The Trojan Asteroids ; V.Šmēlings. Men on the Moon! ; E.Bervalds. Astronomical Domes and “Sauna” ; Z.Alksne, A.Alksnis. Sakurai’s Object Fails to Escape Own Dust ; Z.Alksne, A.Alksnis. R CrB Stars Surrounded by Dust Clouds ; M.Gills. April Started with Astronomy ; A.Alksnis. First Stamps Dedicated to Astronomy by Latvia’s Post-Office ; I.Pundure. Arturs Balklavs and Astronomy of Latvia (till 1969) ; M.Sudārs. Satellite Collisions – What Threat Do They Pose? ; I.Vilks. Dwarf Planets Names in Latvian ; Announcement on the 2nd International Symposium on Dark-sky Parks: 14-19 September 2009, Slovenia ; A.Andžāns. The Best Way to Fight Darkness Is to Switch on Light (Intervi…
Confrontation of cryptic diversity and mate discrimination within Gammarus pulex and Gammarus fossarum species complexes.
2014
16 pages; International audience; Freshwater amphipods Gammarus fossarum and Gammarus pulex are widespread in Europe, with some evidence of cryptic diversity in the former. We used DNA barcoding to assess genetic diversity within and among amphipod populations and examined mate discrimination and pre-copulatory pair formation between genetically divergent individuals. Eight distinct G. fossarum and four distinct G. pulex molecular operational taxonomic units (MOTUs) were detected. Among the 33 amphipod populations sampled, 11 contained a single MOTU, 11 had two and 11 were composed of three sympatric MOTUs. Genetic divergences between sympatric MOTUs (G. fossarum and G. pulex MOTUs combined…
Increased susceptibility to predation and altered anti-predator behaviour in an acanthocephalan-infected amphipod.
2007
7 pages; International audience; According to the 'parasitic manipulation hypothesis', phenotypic changes induced by parasites in their intermediate hosts are effective means of increasing trophic transmission to final hosts. One obvious prediction, although seldom tested, is that increased vulnerability of infected prey to an appropriate predator should be achieved by the parasite altering the anti-predator behaviour of its intermediate host. In this study, we tested this prediction using the fish acanthocephalan Pomphorhynchus tereticollis and the freshwater amphipod Gammarus pulex. Firstly, we estimated the relative vulnerability of infected and uninfected gammarids to predation by the b…
Infection with acanthocephalans increases the vulnerability of Gammarus pulex (Crustacea, Amphipoda) to non-host invertebrate predators.
2008
SUMMARYPhenotypic alterations induced by parasites in their intermediate hosts often result in enhanced trophic transmission to appropriate final hosts. However, such alterations may also increase the vulnerability of intermediate hosts to predation by non-host species. We studied the influence of both infection with 3 different acanthocephalan parasites (Pomphorhynchus laevis, P. tereticollis, and Polymorphus minutus) and the availability of refuges on the susceptibility of the amphipod Gammarus pulex to predation by 2 non-host predators in microcosms. Only infection with P. laevis increased the vulnerability of amphipods to predation by crayfish, Orconectes limosus. In contrast, in the ab…
Host manipulation of a freshwater crustacean (Gammarus roeseli) by an acanthocephalan parasite (Polymorphus minutus) in a biological invasion context.
2006
8 pages; International audience; Several gammarid species serve as intermediate hosts for the acanthocephalan parasite Polymorphus minutus. This parasite influences gammarid behaviour in order to favour transmission to its ultimate host, generally a bird. We investigated this host manipulation in Gammarus roeseli, a gammarid species introduced in France 150 years ago which now coexists with several exotic species from different origins. In the field, vertical distribution of G. roeseli revealed a higher proportion of infected individuals close to the water's surface and the size distribution of infected gammarids revealed predation pressure on infected individuals. However, under laboratory…
Modification of hosts' behavior by a parasite: field evidence for adaptive manipulation.
2007
9 pages; International audience; Parasites relying on trophic transmission to complete their life cycles often induce modifications of their host's behavior in ways that may increase their susceptibility to predation by final hosts. These modifications have often been interpreted as parasite adaptations, but very few studies have demonstrated that host manipulation has fitness benefits for the parasite. The aim of the present study was to address the adaptive significance of parasite manipulation by coupling observations of behavioral manipulation to estimates of trophic transmission to the definitive host in the natural environment. We show that the acanthocephalan parasite Pomphorhynchus …
Manipulative parasites may not alter intermediate host distribution but still enhance their transmission: field evidence for increased vulnerability …
2013
SUMMARYBehavioural alterations induced by parasites in their intermediate hosts can spatially structure host populations, possibly resulting in enhanced trophic transmission to definitive hosts. However, such alterations may also increase intermediate host vulnerability to non-host predators. Parasite-induced behavioural alterations may thus vary between parasite species and depend on each parasite definitive host species. We studied the influence of infection with 2 acanthocephalan parasites (Echinorhynchus truttae and Polymorphus minutus) on the distribution of the amphipod Gammarus pulex in the field. Predator presence or absence and predator species, whether suitable definitive host or …