2,028 research outputs found
A Note on Frame Dragging
The measurement of spin effects in general relativity has recently taken
centre stage with the successfully launched Gravity Probe B experiment coming
toward an end, coupled with recently reported measurements using laser ranging.
Many accounts of these experiments have been in terms of frame-dragging. We
point out that this terminology has given rise to much confusion and that a
better description is in terms of spin-orbit and spin-spin effects. In
particular, we point out that the de Sitter precession (which has been mesured
to a high accuracy) is also a frame-dragging effect and provides an accurate
benchmark measurement of spin-orbit effects which GPB needs to emulate
Lunar Fluid Core and Solid-Body Tides
Variations in rotation and orientation of the Moon are sensitive to solid-body tidal dissipation, dissipation due to relative motion at the fluid-core/solid-mantle boundary, and tidal Love number k2 [1,2]. There is weaker sensitivity to flattening of the core-mantle boundary (CMB) [2-5] and fluid core moment of inertia [1]. Accurate Lunar Laser Ranging (LLR) measurements of the distance from observatories on the Earth to four retroreflector arrays on the Moon are sensitive to lunar rotation and orientation variations and tidal displacements. Past solutions using the LLR data have given results for dissipation due to solid-body tides and fluid core [1] plus Love number [1-5]. Detection of CMB flattening has been improving [3,5] and now seems significant. This strengthens the case for a fluid lunar core
Impact of Technology on Meat Safety
Innovations and new technologies tend to create apprehension among consumers who are not familiar with the technologies and their mode of action. This case currently exists regarding the use of hormones, antibiotics and other feed additives in livestock production. The purpose of this fact sheet is to familiarize consumers with some of the products of technology that are currently utilized in the production of meat animals and to provide an evaluation of how these products impact the safety of meat and meat products
Wind-tunnel study of Four Allen Center, Houston
May 1982.For Century Development Corporation.CER81-82JAP-JEC-BB-DWB66.Includes bibliographical references (pages 36-37).CSU Projects 2-27840 and 2-27940
Anatomy of the binary black hole recoil: A multipolar analysis
We present a multipolar analysis of the gravitational recoil computed in
recent numerical simulations of binary black hole (BH) coalescence, for both
unequal masses and non-zero, non-precessing spins. We show that multipole
moments up to and including l=4 are sufficient to accurately reproduce the
final recoil velocity (within ~2%) and that only a few dominant modes
contribute significantly to it (within ~5%). We describe how the relative
amplitudes, and more importantly, the relative phases, of these few modes
control the way in which the recoil builds up throughout the inspiral, merger,
and ringdown phases. We also find that the numerical results can be reproduced
by an ``effective Newtonian'' formula for the multipole moments obtained by
replacing the radial separation in the Newtonian formulae with an effective
radius computed from the numerical data. Beyond the merger, the numerical
results are reproduced by a superposition of three Kerr quasi-normal modes
(QNMs). Analytic formulae, obtained by expressing the multipole moments in
terms of the fundamental QNMs of a Kerr BH, are able to explain the onset and
amount of ``anti-kick'' for each of the simulations. Lastly, we apply this
multipolar analysis to help explain the remarkable difference between the
amplitudes of planar and non-planar kicks for equal-mass spinning black holes.Comment: 28 pages, 20 figures, submitted to PRD; v2: minor revisions from
referee repor
Modeling kicks from the merger of generic black-hole binaries
Recent numerical relativistic results demonstrate that the merger of
comparable-mass spinning black holes has a maximum ``recoil kick'' of up to
\sim 4000 \kms. However the scaling of these recoil velocities with mass
ratio is poorly understood. We present new runs showing that the maximum
possible kick perpendicular to the orbital plane does not scale as
(where is the symmetric mass ratio), as previously proposed, but is more
consistent with , at least for systems with low orbital precession.
We discuss the effect of this dependence on galactic ejection scenarios and
retention of intermediate-mass black holes in globular clusters.Comment: 5 pages, 1 figure, 3 tables. Version published in Astrophys. J. Let
South Dakota Retained Ownership Demonstration
Three hundred forty-five steer calves representing 53 cow-calf producers were consigned to a custom feedlot in late October. Cattle were fed in one of two pens. One pen of calves received a moderate roughage growing diet for 39 days and then were switched to a high energy finishing diet (ACC). The other pen of calves received a moderate roughage growing diet for 109 days and then were switched to a high energy finishing diet (TWO). The ACC calves weighed 574 lb initially, gained 2.94 Ib per head daily and were slaughtered at 1147 Ib after an average of 196 days on feed. Average cost of gain and profitability were 38.75 per head, respectively. The TWO calves weighed 504 Ib initially, gained 2.77 Ib per head daily and were slaughtered at 1096 Ib after an average of 214 days on feed. Average cost of gain and profitability were 16.69 per head, respectively. Cattle slaughtered later in the spring were less profitable than cattle slaughtered earlier in the spring due to a weaker cattle market and wider choice-select price spread. Across either feeding program, average profits for cattle slaughtered after 170, 192, 199, 200 and 242 days on feed were 64.42, 27.39 and -$16.78 per head, respectively
A Soft X-Ray Spectral Episode for the Clocked Burster, GS 1826-24 as Measured by Swift and NuSTAR
We report on NuSTAR and Swift observations of a soft state of the neutron
star low-mass X-ray binary GS 1826-24, commonly known as the "clocked" burster.
The transition to the soft state was recorded in 2014 June through an increase
of the 2-20 keV source intensity measured by MAXI, simultaneous with a decrease
of the 15-50 keV intensity measured by Swift/BAT. The episode lasted
approximately two months, after which the source returned to its usual hard
state. We analyze the broad-band spectrum measured by Swift/XRT and NuSTAR, and
estimate the accretion rate during the soft episode to be about 13% of
Eddington, within the range of previous observations. However, the best fit
spectral model, adopting the double Comptonization used previously, exhibits
significantly softer components. We detect seven type-I X-ray bursts, all
significantly weaker (and with shorter rise and decay times) than observed
previously. The burst profiles and recurrence times vary significantly, ruling
out the regular bursts that are typical for this source. One burst exhibited
photospheric radius expansion, and we estimate the source distance at about
(5.7 / xi_b^1/2) kpc, where xi_b parameterizes the possible anisotropy of the
burst emission. Interpreting the soft state as a transition from an optically
thin inner flow to an optically thick flow passing through a boundary layer, as
is commonly observed in similar systems, is contradicted by the lower optical
depth measured for the double Comptonization model we find for this soft state.
The effect of a change in disk geometry on the burst behavior remains unclear.Comment: 40 pages (single-column, doubled spaced format), 9 figures, 3 tables;
submitted to Ap
The influence of locomotion on air-sac pressures in little penguins
© The Company of BiologistsAir-sac pressures have been reported to oscillate with wing beat in flying magpies and with foot paddling in diving ducks. We sought to determine the impact on air-sac pressure of wing beats during swimming and of the step cycle during walking in little penguins (Eudyptula minor). Fluctuations averaged 0.16±0.06 kPa in the interclavicular air sacs, but only 0.06±0.04 kPa in the posterior thoracic sac, generating a small differential pressure between sacs of 0.06±0.02 kPa (means ± S.E.M., N=4). These fluctuations occurred at approximately 3 Hz and corresponded to wing beats during swimming, indicated by electromyograms from the pectoralis and supracoracoideus muscles. There was no abdominal muscle activity associated with swimming or exhalation, but the abdominal muscles were active with the step cycle in walking penguins, and oscillations in posterior air-sac pressure (0.08±0.038 kPa) occurred with steps. We conclude that high-frequency oscillations in differential air-sac pressure enhance access to and utilization of the O2 stores in the air sacs during a dive.D.F. Boggs, R.V. Baudinette, P.B. Frappell and P.J. Butle
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