7,777 research outputs found
Atomic and Molecular Opacities for Brown Dwarf and Giant Planet Atmospheres
We present a comprehensive description of the theory and practice of opacity
calculations from the infrared to the ultraviolet needed to generate models of
the atmospheres of brown dwarfs and extrasolar giant planets. Methods for using
existing line lists and spectroscopic databases in disparate formats are
presented and plots of the resulting absorptive opacities versus wavelength for
the most important molecules and atoms at representative temperature/pressure
points are provided. Electronic, ro-vibrational, bound-free, bound-bound,
free-free, and collision-induced transitions and monochromatic opacities are
derived, discussed, and analyzed. The species addressed include the alkali
metals, iron, heavy metal oxides, metal hydrides, , , , ,
, , , and representative grains. [Abridged]Comment: 28 pages of text, plus 22 figures, accepted to the Astrophysical
Journal Supplement Series, replaced with more compact emulateapj versio
Distinguishing between similar tubular objects using pulse reflectometry:a study of trumpet and cornet leadpipes
This paper considers the measurement of the internal radius of a number of similar, short, tubular leadpipes using pulse reflectometry. Pulse reflectometry is an acoustical technique for measuring the internal bore of a tubular object by analysing the reflections which occur when an acoustical pulse is directed into the object. The leadpipes are designed to form the initial, or lead, part of a trumpet or cornet and their internal radii differ by less than 0.1 mm between similar pipes. The ability of the reflectometer to detect these small differences, which are considered by players to produce a noticeable difference in the sound of an instrument, are investigated. It is seen that the pulse reflectometer is able to distinguish between leadpipes with different nominal radii varying by as little as 0.03 mm, demonstrating its potential in the study of musical instruments and showing that it can be used as a diagnostic tool by the instrument manufacturer to detect defects which are significant enough to acoustically alter performance. The absolute accuracy of the radius measurements is also considered at the end of the leadpipe, where the uncertainty is ±0.05 mm
Behavior and Weight Loss of Feeder Calves in a Railcar Modified for Feeding and Watering in Transit
The behavior of 164kg Angus and Hereford calves was studied in a double deck 26m x 2.6m jumbo railcar equipped with feed and water. A 4,180 liter water tank positioned in the center of each deck divided the car into four compartments. Fifty head were loaded into the lower and upper forward compartment (252kg/m2floor space], each containing 675kg of hay in racks. The two rear compartments served as quarters for equipment and researchers. Two video cameras were mounted in the upper forward compartment containing calves. Behavior of the calves was monitored, with portions video taped during rail transport from Memphis, Tennessee to Amarillo, Texas (57 hr) in June, 1979. The calves commenced eating and drinking immediately after being loaded in the railcar. Up to 75% of the cattle could lie down while the car was not in motion (14.4 hr of trip]. Calves stood at high speeds (80km/h] on unimproved track but continued to eat, drink and move about. Self and mutual grooming commonly occurred while traveling up to 40km/hr. Railcar temperature and relative humidity ranged from 17.8 to 41.1°C and 54 to 99%, respectively, and was identical to outside. Weight loss for 50 similar calves shipped by truck was 10.6% while rail calves lost 4.5% during truck transport to the railcar (11.3 hr) and 2.1% during rail transport for a total of 6.6%. Average daily gain (ADG) from initial weight to 7 days postshipment was .45kg for rail and -.02kg for truck, but ADG became similar at 30 days indicating full recovery. One truck calf was dead on arrival and 8% of the truck and 5% of the rail calves were treated for shipping fever. Excluding feedcosts, rail transport at 252kg/m 2 floor space costs 30% less per calf than transport in fully loaded trucks
Behavior and Weight Loss of Feeder Calves in a Railcar Modified for Feeding and Watering in Transit
The behavior of Angus and Hereford calves was studied in a double deck 26m x 2.6m jumbo railcar equipped with feed and water. A 4,180-liter water tank positioned in the center of each deck divided the car into four compartments. Fifty heads were loaded into the lower and upper forward compartments (252kg/m2 floor space], each containing 675kg of hay in racks. The two rear compartments served as quarters for equipment and researchers. Two video cameras were mounted in the upper forward compartment containing calves. The behavior of the calves was monitored, with portions video-taped during rail transport from Memphis, Tennessee, to Amarillo, Texas (57 hours) in June 1979. The calves commenced eating and drinking immediately after being loaded in the railcar. Up to 75% of the calves could lie down while the car was not in motion (14.4 hours of the trip]. Calves stood at high speeds (80km/h] on an unimproved track but continued to eat, drink and move about. Self and mutual grooming commonly occur while traveling up to 40km/hr. Railcar temperature and relative humidity ranged from 17.8 to 41.1oC and 54 to 99%, respectively, and were identical to the outside. Weight loss for 50 similar calves shipped by truck was 10.6%, while rail calves lost 4.5% during truck transport to the railcar (11.3 hours] and 2.1% during rail transport for a total of 6.6%. Average daily gain (ADG) from initial weight to 7 days post shipment was .45kg for rail and -.02 kilograms for truck, but ADG became similar at 30 days indicating full recovery. One truck calf was dead on arrival, and 8% of the truck and 5% of the rail calves were treated for shipping fever. Excluding feed costs, rail transport at 252kglm 2-floor space costs 30% less per calf than transport in fully loaded trucks
Nonlinear Dynamics of Aeolian Sand Ripples
We study the initial instability of flat sand surface and further nonlinear
dynamics of wind ripples. The proposed continuous model of ripple formation
allowed us to simulate the development of a typical asymmetric ripple shape and
the evolution of sand ripple pattern. We suggest that this evolution occurs via
ripple merger preceded by several soliton-like interaction of ripples.Comment: 6 pages, 3 figures, corrected 2 typo
Polymer Induced Bundling of F-actin and the Depletion Force
The inert polymer polyethylene glycol (PEG) induces a "bundling" phenomenon
in F-actin solutions when its concentration exceeds a critical onset value C_o.
Over a limited range of PEG molecular weight and ionic strength, C_o can be
expressed as a function of these two variables. The process is reversible, but
hysteresis is also observed in the dissolution of the bundles, with ionic
strength having a large influence. Additional actin filaments are able to join
previously formed bundles. Little, if any, polymer is associated with the
bundle structure.
Continuum estimates of the Asakura-Oosawa depletion force, Coulomb repulsion,
and van der Waals potential are combined for a partial explanation of the
bundling effect and hysteresis. Conjectures are presented concerning the
apparent limit in bundle size
On the investigations of galaxy redshift periodicity
In this article we present a historical review of study of the redshift
periodicity of galaxies, starting from the first works performed in the
seventies of the twentieth century until the present day. We discuss the
observational data and methods used, showing in which cases the discretization
of redshifts was observed. We conclude that galaxy redshift periodisation is an
effect which can really exist. We also discussed the redshift discretization in
two different structures: the Local Group of galaxies and the Hercules
Supercluster. Contrary to the previous studies we consider all galaxies which
can be regarded as a structure member disregarding the accuracy of velocity
measurements. We applied the power spectrum analysis using the Hann function
for weighting, together with the jackknife error estimator. In both the
structures we found weak effects of redshift periodisation.Comment: 10 pages, 4 figures, to be published in Part. and Nucl. Lett. 200
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