7,432 research outputs found
Commissioning of the ATLAS Level-1 Trigger with Cosmic Rays
The ATLAS detector at CERN's Large Hadron Collider will be exposed to
proton-proton collisions from beams crossing at 40 MHz. A three-level trigger
system was designed to select potentially interesting events and reduce the
incoming rate to 100-200 Hz. The first trigger level (LVL1) is implemented in
custom-built electronics, the second and third trigger levels are realized in
software. Based on calorimeter information and hits in dedicated muon-trigger
detectors, the LVL1 decision is made by the central-trigger processor yielding
an output rate of less than 100 kHz. The allowed latency for the trigger
decision at this stage is less than 2.5 microseconds. Installation of the final
LVL1 trigger system at the ATLAS site is in full swing, to be completed later
this year. We present a status report of the main components of the first-level
trigger and the in-situ commissioning of the full trigger chain with cosmic-ray
muons.Comment: On behalf of the ATLAS TDAQ Level-1 Trigger Group. Proceedings for
2007 Europhysics Conference on High Energy Physics, Manchester, July 200
Seven zero nine zero computer program for determination of precision lattice constants
Computer program for calculation of lattice parameters for cubic, tetragonal, and hexagonal crystals - magnesium oxide and aluminum oxid
Optical Rectification and Field Enhancement in a Plasmonic Nanogap
Metal nanostructures act as powerful optical antennas[1, 2] because
collective modes of the electron fluid in the metal are excited when light
strikes the surface of the nanostructure. These excitations, known as plasmons,
can have evanescent electromagnetic fields that are orders of magnitude larger
than the incident electromagnetic field. The largest field enhancements often
occur in nanogaps between plasmonically active nanostructures[3, 4], but it is
extremely challenging to measure the fields in such gaps directly. These
enhanced fields have applications in surface-enhanced spectroscopies[5-7],
nonlinear optics[1, 8-10], and nanophotonics[11-15]. Here we show that
nonlinear tunnelling conduction between gold electrodes separated by a
subnanometre gap leads to optical rectification, producing a DC photocurrent
when the gap is illuminated. Comparing this photocurrent with low frequency
conduction measurements, we determine the optical frequency voltage across the
tunnelling region of the nanogap, and also the enhancement of the electric
field in the tunnelling region, as a function of gap size. The measured field
enhancements exceed 1000, consistent with estimates from surface-enhanced Raman
measurements[16-18]. Our results highlight the need for more realistic
theoretical approaches that are able to model the electromagnetic response of
metal nanostructures on scales ranging from the free space wavelength,
, down to , and for experiments with new materials,
different wavelengths, and different incident polarizations.Comment: 15 pages, 5 figures + 12 pages, 5 figures of supplemental informatio
Insurance loss coverage under restricted risk classification: The case of iso-elastic demand
This paper investigates equilibrium in an insurance market where risk classification is restricted. Insurance demand is characterised by an iso-elastic function with a single elasticity parameter. We characterise the equilibrium by three quantities: equilibrium premium; level of adverse selection (in the economist’s sense); and “loss coverage”, defined as the expected population losses compensated by insurance. We consider both equal elasticities for high and low risk-groups, and then different elasticities. In the equal elasticities case, adverse selection is always higher under pooling than under risk-differentiated premiums, while loss coverage first increases and then decreases with demand elasticity. We argue that loss coverage represents the efficacy of insurance for the whole population; and therefore that if demand elasticity is sufficiently low, adverse selection is not always a bad thing
Regional variability in the trophic requirements of shelf sea fisheries in the Northeast Atlantic, 1973-2000
Hydrographic, plankton, benthos, fisheries landings, and fish diet data from shelf sea areas in the Northeast Atlantic have been combined into an analysis of the foodweb structure and secondary production requirements of regional fisheries. Fish landings from the Baltic and North Sea are shown to be taken from a lower trophic level and are shown to be overall more planktivorous than those from shelf edge regions. The secondary production required per unit of landed fish from the North Sea was approximately half that for landings from the southwest approaches to the UK, referred to as the Celtic Seas, where zooplankton production accounted for only a small fraction of the secondary production demands of the fisheries. In the North Sea, variability in zooplankton production seems to have exerted a bottom-up effect on fish production, which in turn has exerted a top-down effect on the benthos. Conversely, Celtic Seas benthos production has been a bottom-up driver of fish production, which seems to have been independent of variability in plankton production.Thus, climate and fishing pressures can be expected to influence these regional fisheries in very different ways. Overall, the results indicate very strong spatial patterns in the fish foodweb structure and function, which will be important considerations in the establishment of regional management plans for fisheries
Length-dependent conductance and thermopower in single-molecule junctions of dithiolated oligophenylene derivatives
We study theoretically the length dependence of both conductance and
thermopower in metal-molecule-metal junctions made up of dithiolated
oligophenylenes contacted to gold electrodes. We find that while the
conductance decays exponentially with increasing molecular length, the
thermopower increases linearly as suggested by recent experiments. We also
analyze how these transport properties can be tuned with methyl side groups.
Our results can be explained by considering the level shifts due to their
electron-donating character as well as the tilt-angle dependence of conductance
and thermopower. Qualitative features of the substituent effects in our
density-functional calculations are explained using a tight-binding model. In
addition, we observe symmetry-related even-odd transmission channel
degeneracies as a function of molecular length.Comment: 7 pages, 9 figures; submitted to Phys. Rev.
Computation with Advice
Computation with advice is suggested as generalization of both computation
with discrete advice and Type-2 Nondeterminism. Several embodiments of the
generic concept are discussed, and the close connection to Weihrauch
reducibility is pointed out. As a novel concept, computability with random
advice is studied; which corresponds to correct solutions being guessable with
positive probability. In the framework of computation with advice, it is
possible to define computational complexity for certain concepts of
hypercomputation. Finally, some examples are given which illuminate the
interplay of uniform and non-uniform techniques in order to investigate both
computability with advice and the Weihrauch lattice
Detecting BS in Health Care 2.0
In our initial report “Detecting BS in Health Care,” we identified our top ten BS concepts and trends within the health care industry, and encouraged our readers to hone their “BS detection skills.” Many of you have let us know that we “left some BS on the table.” For example, there are more Old English terms for BS that we missed—such as babble, bafflegab, bilge, blather, blarney, bosh—and these are just from the b’s. This time around we make bolder assertions about other possible forms of BS—including some sacred cows—that might make some readers uncomfortable
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