2,594 research outputs found
Plant Driven Movement: Does Plant Quality Affect the Foraging Patterns of Successful Male Sage-Grouse (Centrocercus Urophasianus)?
The structural and dietary quality of plants is highly variable across the landscape and may influence energy acquisition by herbivores needed for energy dependent activities. For sage-grouse, male display efforts are energetically expensive, with successful males expending up to four times their basal metabolic rate to display. Previous work found that males who had the greatest energy expenditure during the lekking season also lost the least weight and foraged farthest from the lek. We hypothesized that the energetic benefit of foraging farther from the lek is due to higher quality food or cover compared to near lek vegetation. To initially test this hypothesis, we quantified the structural and nutritional quality of sagebrush at different distances away from the lek as well as at patches used by sage-grouse for foraging and roosting. We found no difference in density, percent cover, or height of live or dead sagebrush among different distances (edge, 100, 200, 400 or 800 m) away from leks, but there was a trend for plants near the lek edge to have higher crude protein than those farther away from leks. We found no difference in percent grass, percent forbs, volume of sagebrush, or crude protein of sagebrush among forage, roost, or near lek (100 m from edge) patches, but forage patches tended to have taller sagebrush than roost or near lek patches. The preliminary results suggest that selection for off-lek patches by male sage-grouse may not be driven by the structural or nutritional quality of plants. We propose that plant chemical components may be more indicative of off-lek habitat use by male sage-grouse during the lekking period
Ageing test of the ATLAS RPCs at X5-GIF
An ageing test of three ATLAS production RPC stations is in course at X5-GIF,
the CERN irradiation facility. The chamber efficiencies are monitored using
cosmic rays triggered by a scintillator hodoscope. Higher statistics
measurements are made when the X5 muon beam is available. We report here the
measurements of the efficiency versus operating voltage at different source
intensities, up to a maximum counting rate of about 700Hz/cm^2. We describe the
performance of the chambers during the test up to an overall ageing of 4 ATLAS
equivalent years corresponding to an integrated charge of 0.12C/cm^2, including
a safety factor of 5.Comment: 4 pages. Presented at the VII Workshop on Resistive Plate Chambers
and Related Detectors; Clermont-Ferrand October 20th-22nd, 200
The Study of TeV Variability and Duty Cycle of Mrk 421 from 3 Years of Observations with the Milagro Observatory
TeV flaring activity with time scales as short as tens of minutes and an
orphan TeV flare have been observed from the blazar Markarian 421 (Mrk 421).
The TeV emission from Mrk 421 is believed to be produced by leptonic
synchrotron self-Compton (SSC) emission. In this scenario, correlations between
the X-ray and the TeV fluxes are expected, TeV orphan flares are hardly
explained and the activity (measured as duty cycle) of the source at TeV
energies is expected to be equal or less than that observed in X-rays if only
SSC is considered. To estimate the TeV duty cycle of Mrk 421 and to establish
limits on its variability at different time scales, we continuously observed
Mrk 421 with the Milagro observatory. Mrk 421 was detected by Milagro with a
statistical significance of 7.1 standard deviations between 2005 September 21
and 2008 March 15. The observed spectrum is consistent with previous
observations by VERITAS. We estimate the duty cycle of Mrk 421 for energies
above 1 TeV for different hypothesis of the baseline flux and for different
flare selections and we compare our results with the X-ray duty cycle estimated
by Resconi et al. 2009. The robustness of the results is discussed.Comment: 27 pages, 6 figures, ApJ accepte
In Situ Kinase Profiling Reveals Functionally Relevant Properties of Native Kinases
SummaryProtein kinases are intensely studied mediators of cellular signaling, yet important questions remain regarding their regulation and in vivo properties. Here, we use a probe-based chemoprotemics platform to profile several well studied kinase inhibitors against >200 kinases in native cell proteomes and reveal biological targets for some of these inhibitors. Several striking differences were identified between native and recombinant kinase inhibitory profiles, in particular, for the Raf kinases. The native kinase binding profiles presented here closely mirror the cellular activity of these inhibitors, even when the inhibition profiles differ dramatically from recombinant assay results. Additionally, Raf activation events could be detected on live cell treatment with inhibitors. These studies highlight the complexities of protein kinase behavior in the cellular context and demonstrate that profiling with only recombinant/purified enzymes can be misleading
Search for Branons at LEP
We search, in the context of extra-dimension scenarios, for the possible
existence of brane fluctuations, called branons. Events with a single photon or
a single Z-boson and missing energy and momentum collected with the L3 detector
in e^+ e^- collisions at centre-of-mass energies sqrt{s}=189-209$ GeV are
analysed. No excess over the Standard Model expectations is found and a lower
limit at 95% confidence level of 103 GeV is derived for the mass of branons,
for a scenario with small brane tensions. Alternatively, under the assumption
of a light branon, brane tensions below 180 GeV are excluded
Study of Spin and Decay-Plane Correlations of W Bosons in the e+e- -> W+W- Process at LEP
Data collected at LEP at centre-of-mass energies \sqrt(s) = 189 - 209 GeV are
used to study correlations of the spin of W bosons using e+e- -> W+W- -> lnqq~
events. Spin correlations are favoured by data, and found to agree with the
Standard Model predictions. In addition, correlations between the W-boson decay
planes are studied in e+e- -> W+W- -> lnqq~ and e+e- -> W+W- -> qq~qq~ events.
Decay-plane correlations, consistent with zero and with the Standard Model
predictions, are measured
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