373 research outputs found
Model for Kinetic Effects on Calcium Isotope Fractionation (d44Ca) in Inorganic Aragonite and Cultured Planktonic Foraminifera
TRAUMA-RELATED NIGHTMARES AMONG AMERICAN INDIAN VETERANS: VIEWS FROM THE DREAM CATCHER
Abstract: Dreams hold particular relevance in mental health work with American Indians (AI
Benefits of Artificially Generated Gravity Gradients for Interferometric Gravitational-Wave Detectors
We present an approach to experimentally evaluate gravity gradient noise, a
potentially limiting noise source in advanced interferometric gravitational
wave (GW) detectors. In addition, the method can be used to provide sub-percent
calibration in phase and amplitude of modern interferometric GW detectors.
Knowledge of calibration to such certainties shall enhance the scientific
output of the instruments in case of an eventual detection of GWs. The method
relies on a rotating symmetrical two-body mass, a Dynamic gravity Field
Generator (DFG). The placement of the DFG in the proximity of one of the
interferometer's suspended test masses generates a change in the local
gravitational field detectable with current interferometric GW detectors.Comment: 16 pages, 4 figure
Constraints on Light Pseudoscalars Implied by Tests of the Gravitational Inverse-Square Law
The exchange of light pseudoscalars between fermions leads to a
spin-independent potential in order g^4, where g is the Yukawa
pseudoscalar-fermion coupling constant. This potential gives rise to detectable
violations of both the weak equivalence principle (WEP) and the gravitational
inverse-square law (ISL), even if g is quite small. We show that when
previously derived WEP constraints are combined with those arisingfrom ISL
tests, a direct experimental limit on the Yukawa coupling of light
pseudoscalars to neutrons can be inferred for the first time (g_n^2/4pi < 1.6
\times 10^-7), along with a new (and significantly improved) limit on the
coupling of light pseudoscalars to protons.Comment: 12 pages, Revtex, with 1 Postscript figure (submitted to Physical
Review Letters
The potential effects of climate change on air quality across the conterminous US at 2030 under three Representative Concentration Pathways
The potential impacts of climate change on regional ozone (O3) and
fine particulate (PM2.5) air quality in the United States (US) are
investigated by linking global climate simulations with regional-scale
meteorological and chemical transport models. Regional climate at 2000 and
at 2030 under three Representative Concentration Pathways (RCPs) is simulated by
using the Weather Research and Forecasting (WRF) model to downscale 11-year
time slices from the Community Earth System Model (CESM). The downscaled
meteorology is then used with the Community Multiscale Air Quality (CMAQ)
model to simulate air quality during each of these 11-year periods. The
analysis isolates the future air quality differences arising from
climate-driven changes in meteorological parameters and specific natural
emissions sources that are strongly influenced by meteorology. Other factors
that will affect future air quality, such as anthropogenic air pollutant
emissions and chemical boundary conditions, are unchanged across the
simulations. The regional climate fields represent historical daily maximum
and daily minimum temperatures well, with mean biases of less than 2 K for most
regions of the US and most seasons of the year and good representation of
variability. Precipitation in the central and eastern US is well simulated
for the historical period, with seasonal and annual biases generally less
than 25 %, with positive biases exceeding 25 % in the western US throughout
the year and in part of the eastern US during summer. Maximum daily 8 h
ozone (MDA8 O3) is projected to increase during summer and autumn in
the central and eastern US. The increase in summer mean MDA8 O3 is
largest under RCP8.5, exceeding 4 ppb in some locations, with smaller
seasonal mean increases of up to 2 ppb simulated during autumn and changes
during spring generally less than 1 ppb. Increases are magnified at the upper
end of the O3 distribution, particularly where projected increases in
temperature are greater. Annual average PM2.5 concentration changes
range from â1.0 to 1.0 ”g mâ3. Organic PM2.5
concentrations increase during summer and autumn due to increased biogenic
emissions. Aerosol nitrate decreases during winter, accompanied by lesser
decreases in ammonium and sulfate, due to warmer temperatures causing
increased partitioning to the gas phase. Among meteorological factors
examined to account for modeled changes in pollution, temperature and
isoprene emissions are found to have the largest changes and the greatest
impact on O3 concentrations.</p
Sub-millimeter Tests of the Gravitational Inverse-square Law
Motivated by a variety of theories that predict new effects, we tested the
gravitational 1/r^2 law at separations between 10.77 mm and 137 microns using
two different 10-fold azimuthally symmetric torsion pendulums and rotating
10-fold symmetric attractors. Our work improves upon other experiments by up to
a factor of about 100. We found no deviation from Newtonian physics at the 95%
confidence level and interpret these results as constraints on extensions of
the Standard Model that predict Yukawa or power-law forces. We set a constraint
on the largest single extra dimension (assuming toroidal compactification and
that one extra dimension is significantly larger than all the others) of R <=
160 microns, and on two equal-sized large extra dimensions of R <= 130 microns.
Yukawa interactions with |alpha| >= 1 are ruled out at 95% confidence for
lambda >= 197 microns. Extra-dimensions scenarios stabilized by radions are
restricted to unification masses M >= 3.0 TeV/c^2, regardless of the number of
large extra dimensions. We also provide new constraints on power-law potentials
V(r)\propto r^{-k} with k between 2 and 5 and on the gamma_5 couplings of
pseudoscalars with m <= 10 meV/c^2.Comment: 34 pages, 38 figure
The Physics of LIGO
In the spring term of 1994, I organized a course at Caltech on the The Physics of LIGO (i.e., the physics of the Laser Interferometer Gravitational Wave Observatory). The course consisted of eighteen 1.5-hour-long tutorial lectures, delivered by members of the LIGO team and others, and it was aimed at advanced undergraduates and graduate students in physics, applied physics and in engineering and applied sciences and also at interested postdoctoral fellows, research staff, and faculty
Limits on Gravitational-Wave Emission from Selected Pulsars Using LIGO Data
We place direct upper limits on the amplitude of gravitational waves from 28 isolated radio pulsars by a coherent multidetector analysis of the data collected during the second science run of the LIGO interferometric detectors. These are the first direct upper limits for 26 of the 28 pulsars. We use coordinated radio observations for the first time to build radio-guided phase templates for the expected gravitational-wave signals. The unprecedented sensitivity of the detectors allows us to set strain upper limits as low as a few times 10^(-24). These strain limits translate into limits on the equatorial ellipticities of the pulsars, which are smaller than 10^(-5) for the four closest pulsars
Death and the âlife reviewâ in Halakhah
Coping with old age involves resolving the task of âintegrity versus despair,â which demands a nondefensive confrontation with the inevitability of death. Halakhah (Jewish ethics) also considered this task critical in later years of life, spoke of death's inevitability, and attempted to discourage denial of death. The Jewish approach seems compatible with Butler's concept of âlife reviewâ as a reconciliation with death and a reintegration of one's identity that occurs throughout later years. While the Eriksonian goal is confronting old age with a certain capacity for âwisdom,â the rabbis maintained that such wisdom must culminate in the creative act of repentance.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45115/1/10943_2004_Article_BF00996254.pd
First upper limits from LIGO on gravitational wave bursts
We report on a search for gravitational wave bursts using data from the first
science run of the LIGO detectors. Our search focuses on bursts with durations
ranging from 4 ms to 100 ms, and with significant power in the LIGO sensitivity
band of 150 to 3000 Hz. We bound the rate for such detected bursts at less than
1.6 events per day at 90% confidence level. This result is interpreted in terms
of the detection efficiency for ad hoc waveforms (Gaussians and sine-Gaussians)
as a function of their root-sum-square strain h_{rss}; typical sensitivities
lie in the range h_{rss} ~ 10^{-19} - 10^{-17} strain/rtHz, depending on
waveform. We discuss improvements in the search method that will be applied to
future science data from LIGO and other gravitational wave detectors.Comment: 21 pages, 15 figures, accepted by Phys Rev D. Fixed a few small typos
and updated a few reference
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