2,272 research outputs found
Explicit solution of the linearized Einstein equations in TT gauge for all multipoles
We write out the explicit form of the metric for a linearized gravitational
wave in the transverse-traceless gauge for any multipole, thus generalizing the
well-known quadrupole solution of Teukolsky. The solution is derived using the
generalized Regge-Wheeler-Zerilli formalism developed by Sarbach and Tiglio.Comment: 9 pages. Minor corrections, updated references. Final version to
appear in Class. Quantum Gra
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Searches for new particles at D0
We report the results of searches at the Tevatron for first and second generation leptoquarks and for new charged gauge bosons. The data were collected with the D0 detector from {ital p{anti p}} collisions at {radical}s=1.8 TeV. No evidence for the existence of these particles is seen and mass limits are set. We report new preliminary results of a search for a heavy neutral gauge boson in the process Z{prime}{r_arrow}{ital ee}, from an integrated luminosity of 105 pb{sup -1}. We exclude the existence of a Z{prime} of mass less than 670 GeV/c{sup 2}, assuming a Z{prime} with the same coupling strengths to quarks and leptons as the standard model Z boson. 13 refs., 5 figs., 1 tab
What Counts as Evidence in Rural Schools.pdf
This policy breif examines the importance of practice-based evidence for rural education
Particulate organic matter in surface waters off Southern California and its relationship to phytoplankton
Particulate carbon, nitrogen, chlorophyll a, adenosine triphosphate, particle count and particle volume were measured in the euphotic zone during six quarterly cruises (between September, 1974, and March, 1976) in the Southern California Bight. The distribution and quantitative relationships among these parameters were examined in an attempt to estimate the relative contributions of plankton to the total particulate matter...
Black hole head-on collisions and gravitational waves with fixed mesh-refinement and dynamic singularity excision
We present long-term-stable and convergent evolutions of head-on black hole
collisions and extraction of gravitational waves generated during the merger
and subsequent ring-down. The new ingredients in this work are the use of fixed
mesh-refinement and dynamical singularity excision techniques. We are able to
carry out head-on collisions with large initial separations and demonstrate
that our excision infrastructure is capable of accommodating the motion of the
individual black holes across the computational domain as well as their their
merger. We extract gravitational waves from these simulations using the
Zerilli-Moncrief formalism and find the ring-down radiation to be, as expected,
dominated by the l=2, m=0 quasi-normal mode. The total radiated energy is about
0.1 % of the total ADM mass of the system.Comment: Revised version, 1 figure added, accepted for publication in
Phys.Rev.D, 15 pages, 10 figures, revtex 4.
Simple Front End Electronics for Multigap Resistive Plate Chambers
A simple circuit for the presentation of the signals from Multi-gap Resistive
Plate Chambers (MRPCs) to standard existing digitization electronics is
described. The circuit is based on "off-the-shelf" discrete components. An
optimization of the values of specific components is required to match the
aspects of the MRPCs for the given application. This simple circuit is an
attractive option for the initial signal processing for MRPC prototyping and
bench- or beam-testing efforts, as well as for final implementations of
small-area Time-of-Flight systems with existing data acquisition systems.Comment: submitted to Nucl. Inst. and Methods, Section
Determinants of terrestrial feeding in an arboreal primate: the case of Hapalemur meridionalis
Objectives
The proximate and ultimate determinants that may have prompted some primates to shift from an arboreal to terrestrial feeding niche, whether due to environmental change, seasonality, and/or predation pressure, are poorly understood. Within a fragmented littoral forest in southeast Madagascar, an arboreal strepsirrhine population spends a large proportion of time on the ground, thus we aimed to identify which factors influence terrestrial feeding.
Methods
From January to December 2013, we conducted 103 full-day focal follows on three social groups of southern bamboo lemurs H. meridionalis. We continuously recorded feeding time on all arboreal and terrestrial items, as well as whether the focal individual was under the canopy or exposed, and the distance to their nearest conspecific neighbor. All observed food items were collected and analyzed for macronutrient content. Daily climatic variables (temperature, precipitation), resource seasonality, daily path length (DPL), along with dietary and predation risk proxies, were used as fixed effects in a linear mixed model, with the daily proportion of terrestrial feeding as the dependent variable.
Results
Our model indicated that daily terrestrial feeding increased at cooler temperature, was associated with reduced DPL, and the intake of dietary metabolizable energy increased as terrestrial feeding increased. All other fixed effects were not significant predictors.
Discussion
Our study provides a window into the ultimate determinants of niche expansion: ancestral primates, in absence of their primary resources, may have initially descended to the ground in peripheral population range areas where the benefits (e g., nutritional pay-off) out-weighed the costs
Beam energy dependence of moments of the net-charge multiplicity distributions in Au+Au collisions at RHIC
We report the first measurements of the moments -- mean (), variance
(), skewness () and kurtosis () -- of the net-charge
multiplicity distributions at mid-rapidity in Au+Au collisions at seven
energies, ranging from = 7.7 to 200 GeV, as a part of the
Beam Energy Scan program at RHIC. The moments are related to the thermodynamic
susceptibilities of net-charge, and are sensitive to the proximity of the QCD
critical point. We compare the products of the moments, ,
and with the expectations from Poisson and
negative binomial distributions (NBD). The values deviate from
Poisson and are close to NBD baseline, while the values tend
to lie between the two. Within the present uncertainties, our data do not show
non-monotonic behavior as a function of collision energy. These measurements
provide a distinct way of determining the freeze-out parameters in heavy-ion
collisions by comparing with theoretical models.Comment: 7 pages, 4 figures, Accepted by PR
Deep subcutaneous application of poly-L-lactic acid as a filler for facial lipoatrophy in HIV-infected patients
Introduction: Facial lipoatrophy is a crucial problem of HIV-infected patients undergoing highly active antiretroviral therapy (HAART). Poly-L-lactic acid (PLA), provided as New-Fill(R)/Sculptra(TM), is known as one possible treatment option. In 2004 PLA was approved by the FDA as Sculptra(TM) for the treatment of lipoatrophy of the face in HIV-infected patients. While the first trials demonstrated relevant efficacy, this was to some extent linked to unwanted effects. As the depth of injection was considered relevant in this context, the application modalities of the preparation were changed. The preparation was to be injected more deeply into subcutaneous tissue, after increased dilution. Material and Methods: To test this approach we performed a pilot study following the new recommendations in 14 patients. Results: While the efficacy turned out to be about the same, tolerability was markedly improved. The increase in facial dermal thickness was particularly obvious in those patients who had suffered from lipoatrophy for a comparatively small period of time. Conclusion: With the new recommendations to dilute PLA powder and to inject it into the deeper subcutaneous tissue nodule formation is a minor problem. However, good treatment results can only be achieved if lipoatrophy is not too intense; treatment intervals should be about 2 - 3 weeks. Copyright (C) 2005 S. Karger AG, Basel
Implementing an apparent-horizon finder in three dimensions
Locating apparent horizons is not only important for a complete understanding
of numerically generated spacetimes, but it may also be a crucial component of
the technique for evolving black-hole spacetimes accurately. A scheme proposed
by Libson et al., based on expanding the location of the apparent horizon in
terms of symmetric trace-free tensors, seems very promising for use with
three-dimensional numerical data sets. In this paper, we generalize this scheme
and perform a number of code tests to fully calibrate its behavior in
black-hole spacetimes similar to those we expect to encounter in solving the
binary black-hole coalescence problem. An important aspect of the
generalization is that we can compute the symmetric trace-free tensor expansion
to any order. This enables us to determine how far we must carry the expansion
to achieve results of a desired accuracy. To accomplish this generalization, we
describe a new and very convenient set of recurrence relations which apply to
symmetric trace-free tensors.Comment: 14 pages (RevTeX 3.0 with 3 figures
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