7,320 research outputs found
Imprints of a Primordial Preferred Direction on the Microwave Background
Rotational invariance is a well-established feature of low-energy physics.
Violations of this symmetry must be extremely small today, but could have been
larger in earlier epochs. In this paper we examine the consequences of a small
breaking of rotational invariance during the inflationary era when the
primordial density fluctuations were generated. Assuming that a fixed-norm
vector picked out a preferred direction during the inflationary era, we explore
the imprint it would leave on the cosmic microwave background anisotropy, and
provide explicit formulas for the expected amplitudes of
the spherical-harmonic coefficients. We suggest that it is natural to expect
that the imprint on the primordial power spectrum of a preferred spatial
direction is approximately scale-invariant, and examine a simple model in which
this is true.Comment: 7 pages, no figures; v5: Corrections, as well as use of more standard
convention, in section I
Japanese Whaling in the Pacific Ocean: Defiance of International Whaling Norms in the Name of “Scientific Research,” Culture, and Tradition
Japanese whaling practices have always sparked controversy among the international community. Japan\u27s recent defiance of international environmental norms, however, risks a full-scale trade war led by U.S. demands to reform Japan\u27s whaling practices or suffer trade sanctions. Although the species\u27 endangered status may support sanctioning measures under international law, the United States must exercise caution in imposing restraints on international trade in light of its commitments under international trade agreements. The future of Japanese whaling remains unclear, but the international condemnation and call for restrictions is well-founded on international whaling and environmental norms
Determination and impact of surface radiative processes for TOGA COARE
Experiments using atmospheric general circulation models have shown that the atmospheric circulation is very sensitive to small changes in sea surface temperature in the tropical western Pacific Ocean warm pool region. The mutual sensitivity of the ocean and the atmosphere in the warm pool region places stringent requirements on models of the coupled ocean atmosphere system. At present, the situation is such that diagnostic studies using available data sets have been unable to balance the surface energy budget in the warm pool region to better than 50 to 80 W/sq m. The Tropical Ocean Global Atmosphere (TOGA) Coupled Ocean Atmosphere Response Experiment (COARE) is an observation and modelling program that aims specifically at the elucidation of the physical process which determine the mean and transient state of the warm pool region and the manner in which the warm pool interacts with the global ocean and atmosphere. This project focuses on one very important aspect of the ocean atmosphere interface component of TOGA COARE, namely the temporal and spatial variability of surface radiative fluxes in the warm pool region
Cost analysis of a growth guidance system compared with traditional and magnetically controlled growing rods for early-onset scoliosis: A US-based integrated health care delivery system perspective
Integration and Conventional Systems at STAR
At the beginning of the design and construction of the STAR Detector, the
collaboration assigned a team of physicists and engineers the responsibility of
coordinating the construction of the detector. This group managed the general
space assignments for each sub-system and coordinated the assembly and planning
for the detector. Furthermore, as this group was the only STAR group with the
responsibility of looking at the system as a whole, the collaboration assigned
it several tasks that spanned the different sub-detectors. These items included
grounding, rack layout, cable distribution, electrical, power and water, and
safety systems. This paper describes these systems and their performance.Comment: 17 pages, 6 figures, Contribution to a NIM Volume Dedicated to the
Detectors and the Accelerator at RHI
Dark Matter and Dark Radiation
We explore the feasibility and astrophysical consequences of a new long-range
U(1) gauge field ("dark electromagnetism") that couples only to dark matter,
not to the Standard Model. The dark matter consists of an equal number of
positive and negative charges under the new force, but annihilations are
suppressed if the dark matter mass is sufficiently high and the dark
fine-structure constant is sufficiently small. The correct relic
abundance can be obtained if the dark matter also couples to the conventional
weak interactions, and we verify that this is consistent with particle-physics
constraints. The primary limit on comes from the demand that the
dark matter be effectively collisionless in galactic dynamics, which implies
for TeV-scale dark matter. These values are
easily compatible with constraints from structure formation and primordial
nucleosynthesis. We raise the prospect of interesting new plasma effects in
dark matter dynamics, which remain to be explored.Comment: 14 pages, 6 figures Updated equations and figure
Use of aerial survey and aerophotogrammetry methods in monitoring manatee populations
We evaluated the use of strip-transect survey methods for manatees through a
series of replicate aerial surveys in the Banana River, Brevard County, Florida, during
summer 1993 and summer 1994. Transect methods sample a representative portion of
the total study area, thus allowing for statistical extrapolation to the total area. Other
advantages of transect methods are less flight time and less cost than total coverage, ease
of navigation, and reduced likelihood of double-counting.
Our objectives were: (1) to identify visibility biases associated with the transect
survey method and to adjust the counts accordingly; (2) to derive a population estimate
with known variance for the Banana River during summer; and (3) to evaluate the
potential value of this survey method for monitoring trends in manatee population size
over time. (51 page document
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Personal Care Product Use Predicts Urinary Concentrations of Some Phthalate Monoesters
Phthalates are multifunctional chemicals used in a variety of applications, including personal care products. The present study explored the relationship between patterns of personal care product use and urinary levels of several phthalate metabolites. Subjects include 406 men who participated in an ongoing semen quality study at the Massachusetts General Hospital Andrology Laboratory between January 2000 and February 2003. A nurse-administered questionnaire was used to determine use of personal care products, including cologne, aftershave, lotions, hair products, and deodorants. Phthalate monoester concentrations were measured in a single spot urine sample by isotope dilution–high-performance liquid chromatography coupled to tandem mass spectrometry. Men who used cologne or aftershave within 48 hr before urine collection had higher median levels of monoethyl phthalate (MEP) (265 and 266 ng/mL, respectively) than those who did not use cologne or aftershave (108 and 133 ng/mL, respectively). For each additional type of product used, MEP increased 33% (95% confidence interval, 14–53%). The use of lotion was associated with lower urinary levels of monobutyl phthalate (MBP) (14.9 ng/mL), monobenzyl phthalate (MBzP) (6.1 ng/mL), and mono(2-ethylhexyl) phthalate (MEHP) (4.4 ng/mL) compared with men who did not use lotion (MBP, 16.8 ng/mL; MBzP, 8.6 ng/mL; MEHP, 7.2 ng/mL). The identification of personal care products as contributors to phthalate body burden is an important step in exposure characterization. Further work in this area is needed to identify other predictors of phthalate exposure
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