40,433 research outputs found
Powerful jets from accreting black holes: evidence from the optical and infrared
A common consequence of accretion onto black holes is the formation of
powerful, relativistic jets that escape the system. In the case of supermassive
black holes at the centres of galaxies this has been known for decades, but for
stellar-mass black holes residing within galaxies like our own, it has taken
recent advances to arrive at this conclusion. Here, a review is given of the
evidence that supports the existence of jets from accreting stellar-mass black
holes, from observations made at optical and infrared wavelengths. In
particular it is found that on occasion, jets can dominate the emission of
these systems at these wavelengths. In addition, the interactions between the
jets and the surrounding matter produce optical and infrared emission on large
scales via thermal and non-thermal processes. The evidence, implications and
applications in the context of jet physics are discussed. It is shown that many
properties of the jets can be constrained from these studies, including the
total kinetic power they contain. The main conclusion is that like the
supermassive black holes, the jet kinetic power of accreting stellar-mass black
holes is sometimes comparable to their bolometric radiative luminosity. Future
studies can test ubiquities in jet properties between objects, and attempt to
unify the properties of jets from all observable accreting black holes, i.e. of
all masses.Comment: 26 pages, 4 figures, 1 table. Invited chapter for the edited book
"Black Holes and Galaxy Formation", Nova Science Publishers, Inc., at pres
IMPLEMENTATION OF ELECTRONIC MARKETING OF SLAUGHTER CATTLE IN VIRGINIA: REQUIREMENTS AND PROCEDURES
Research and Development/Tech Change/Emerging Technologies,
Application of LANDSAT-2 data to the implementation and enforcement of the Pennsylvania Surface Mining Conservation and Reclamation Act
The author has identified the following significant results. Evaluation of LANDSAT imagery indicates severe limitations in its utility for surface mine land studies. Image stripping resulting from unequal detector response on satellite degrades the image quality to the extent that images of scales larger than 1:125,000 are of limited value for manual interpretation. Computer processing of LANDSAT data to improve image quality is essential; the removal of scanline stripping and enhancement of mine land reflectance data combined with color composite printing permits useful photographic enlargements to approximately 1:60,000
COSTS OF OPERATING A COMPUTERIZED TRADING SYSTEM FOR SLAUGHTER LAMBS
Research and Development/Tech Change/Emerging Technologies,
Lidar measurements of stratospheric aerosols over Menlo Park, California, October 1972 - March 1974
During an 18-month period, 30 nighttime observations of stratospheric aerosols were made using a ground based ruby lidar located near the Pacific coast of central California (37.5 deg. N, 122.2 deg. W). Vertical profiles of the lidar scattering ratio and the particulate backscattering coefficient were obtained by reference to a layer of assumed negligible particulate content. An aerosol layer centered near 21 km was clearly evident in all observations, but its magnitude and vertical distribution varied considerably throughout the observation period. A reduction of particulate backscattering in the 23- to 30-km layer during late January 1973 appears to have been associated with the sudden stratospheric warming which occurred at that time
An excess of damped Lyman alpha galaxies near QSOs
We present a sample of 33 damped Lyman alpha systems (DLAs) discovered in the
Sloan Digital Sky Survey (SDSS) whose absorption redshifts (z_abs) are within
6000 km/s of the QSO's systemic redshift (z_sys). Our sample is based on 731
2.5 < z_sys < 4.5 non-broad-absorption-line (non-BAL) QSOs from Data Release 3
(DR3) of the SDSS. We estimate that our search is ~100 % complete for absorbers
with N(HI) >= 2e20 cm^-2. The derived number density of DLAs per unit redshift,
n(z), within v < 6000 km/s is higher (3.5 sigma significance) by almost a
factor of 2 than that of intervening absorbers observed in the SDSS DR3, i.e.
there is evidence for an overdensity of galaxies near the QSOs. This provides a
physical motivation for excluding DLAs at small velocity separations in surveys
of intervening 'field' DLAs. In addition, we find that the overdensity of
proximate DLAs is independent of the radio-loudness of the QSO, consistent with
the environments of radio-loud and radio-quiet QSOs being similar.Comment: Accepted for publication in MNRAS (13 pages, 6 figures
Sinuosity and the affect grid: A method for adjusting repeated mood scores
Copyright @ 2012 Ammons Scientific. The article can be accessed from the links below.This article has been made available through the Brunel Open Access Publishing Fund.Sinuosity is a measure of how much a travelled pathway deviates from a straight line. In this paper, sinuosity is applied to the measurement of mood. The Affect Grid is a mood scale that requires participants to place a mark on a 9 x 9 grid to indicate their current mood. The grid has two dimensions: pleasure-displeasure (horizontal) and arousal-sleepiness (vertical). In studies where repeated measurements are required, some participants may exaggerate their mood shifts due to faulty interpretation of the scale or a feeling of social obligation to the experimenter. A new equation is proposed, based on the sinuosity measure in hydrology, a measure of the meandering of rivers. The equation takes into account an individual's presumed tendency to exaggerate and meander to correct the score and reduce outliers. The usefulness of the equation is demonstrated by applying it to Affect Grid data from another study.This article is made available through the Brunel Open Access Publishing Fund
Crew appliance concepts. Volume 2, appendix B: Shuttle orbiter appliances supporting engineering data
Technical data collected for the food management and personal hygiene appliances considered for the shuttle orbiter are presented as well as plotted and tabulated trade study results for each appliance. Food storage, food operation, galley cleanup, waste collection/transfer, body cleansing, and personal grooming were analyzed
Lidar measurements of the post-fuego stratospheric aerosol
Fifteen lidar observations of the stratospheric aerosol were made between February and November 1975. All observations revealed the greatly increased particulate backscattering that followed the eruption of the volcano Fuego in October 1974. Vertical structure consisted initially of multiple layers, which later merged to form a single, broader peak. Essentially all of the increased scattering was confined to altitudes below 20 km. Hence, aerosol layer centroids in 1975 were typically several km below their altitude prior to the eruption. Radiative and thermal consequences of the measured post-Fuego layer were computed using several recently published models. The models predict a temperature increase of several K at the altitude of the layer, caused by the infrared absorption bands of the sulfuric acid particles. The surface temperature decrease predicted by the models is considerably smaller than 1 K, partly because of the small optical thickness of the volcanic layer, and partly because of its short residence time relative to the earth-ocean thermal response time
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