5,666 research outputs found
The mass of the black hole in LMC X-3
New high resolution, optical spectroscopy of the high mass X-ray binary LMC X-3, shows the spectral type of the donor star changes with phase due to irradition by the X-ray source. We find the spectral type is likely to be B5V, and only appears as B3V when viewing the heated side of the donor. Combining our measurements with those previously published, and taking into account the effects of X-ray irradiation, results in a value for the donor star radial velocity semi-amplitude of ~km~s. We find the mass of the black hole lies in the range
Quantum effects on Higgs-strahlung events at Linear Colliders within the general 2HDM
The associated production of neutral Higgs bosons with the Z gauge boson is
investigated in the context of the future linear colliders, such as the ILC and
CLIC, within the general two-Higgs-doublet model (2HDM). We compute the
corresponding production cross-sections at one-loop, in full consistency with
the available theoretical and phenomenological constraints. We find that the
wave-function renormalization corrections to the external Higgs fields are the
dominant source of the quantum effects, which turn out to be large and
negative, and located predominantly in the region around \tan\beta=1 and
moderate values of the parameter \lambda_5 (being \lambda_5 < 0). This behavior
can be ultimately traced back to the enhancement potential of the triple Higgs
boson self-couplings, a trademark feature of the 2HDM with no counterpart in
the Higgs sector of the Minimal Supersymmetric Standard Model. The predicted
Higgs-strahlung rates comfortably reach a few tens of femtobarn, which means
barely 10^3 - 10^4 events per 500 inverse femtobarn of integrated luminosity.
Due to their great complementarity, we argue that the combined analysis of the
Higgs-strahlung events and the previously computed one-loop Higgs-pair
production processes could be instrumental to probe the structure of the Higgs
sector at future linac facilities.Comment: LaTeX, 16 pages, 9 Figures, 2 Tables. Extended discussion, references
added, matches published version in Phys. Rev.
Correction of Bathymetric Survey Artifacts Resulting from Apparent Wave-Induced Vertical Position of an AUV
Recent increases in the capability and reliability of autonomous underwater vehicles (AUVs) have provided the opportunity to conduct bathymetric seafloor surveys in shallow water (\u3c 50 m). Unfortunately, surveys of this water depth may contain artifacts induced by large amplitude wave motion at the surface. The artifacts occur when an onboard pressure sensor determines the depth of the AUV. Waves overhead induce small pressure fluctuations at depth, which modulate the AUV’s pressure sensor output without causing actual vertical movement of the AUV. Since bathymetric measurements are made with respect to the AUV’s depth, these pressure fluctuations, in turn, modulate the measurement of the seafloor. The result is a periodic across-track, vertical offset of the seafloor profile (similar to a heave artifact sometimes common in surface vessel surveys). In this paper we describe our experience with the “Gavia” model AUV (Hafmynd EHF, Iceland) in a recent bathymetric survey during which wave action overhead induced such an artifact with a peak-to-peak amplitude as large as 1 meter. A method for removing the artifact as well as recommendations for modifications to the sonar, INS and AUV to mitigate the effect in the future are provided
Structural Geology of Eastern Part of Dairy Ridge Quadrangle and Western Part of Meachum Ridge Quadrangle, Utah
A detailed geologic investigation was made of the eastern part of the Dairy Ridge Quadrangle and the western part of the Meachum Ridge Quadrangle, Utah. The area is located in north-central Utah in Rich County. It lies between lat. 41°22\u2730 N. and lat. 41° 28\u2750 N. and between long. 111° 21\u2740 W. and long. 111°25\u2715 W. The area measures 13.8 km in the north-south direction and 5.5 km in the east-west direction. It is on the eastern side of the Wasatch Range about 20 km west-southwest of Randolph, Utah.
Stratigraphic units of Precambrian to Cambrian age crop out in the western part of the area, above the Woodruff thrust fault, and dip west. These include the Precambrian Mutual Formation and the Cambrian Geertsen Canyon Quartzite. Units of Pennsylvanian to Jurassic age crop out in the eastern part of the area below the Woodruff thrust fault. They dip west and are overturned to the east. These units include the following: Pennsylvanian Weber Formation, Permian Grandeur Member of the Park City Formation, Permian Phosphoria Formation, Triassic Thaynes Limestone, Triassic Ankareh Formation, Jurassic Nugget Sandstone, and Jurassic Twin Creek Limestone. The Tertiary Wasatch Formation unconformably overlies all older units in places.
The Woodruff thrust fault is the major structural feature of the area. Quartzite of the Precambrian Mutual Formation is thrust eastward over the Pennsylvanian Weber Formation as well as over formations of Permian and Triassic ages. The Woodruff thrust fault strikes about N. 20° E. and dips 18° W. to 33° W. Stratigraphic throw is at least 5,800 m. Probable horizontal displacement is tens of kilometers. The stratigraphic units, under the thrust fault, dip west and are overturned to the east. They form the western limb of a large asymmetrical syncline. The overturned units are cut by a west-dipping high-angle thrust fault. The syncline and the thrust faults were produced by the Sevier orogeny which began in latest Jurassic or earliest Cretaceous time. Deformation may have continued into Paleocene time
Changing Banking Habits in Low-income Communities
This paper examines how the current practices within the banking industry have helped influence banking habits within low-income communities. Using existing research data that studied low-income communities’ current banking habits, the growth in check-cashing businesses, and current banking industry practices, this article suggests that changes in the banking industry practices are vital to help promote better banking habits within low-income communities. The impact of such changes will reduce unnecessary financial costs while generating savings that can help these communities build additional cash reserves. The findings show that with the support of banking industry leaders, government regulations, and philanthropic community revitalization efforts, these changes will create more inclusive products and services
Underwater radiated noise levels of a research icebreaker in the central Arctic Ocean
U.S. Coast Guard Cutter Healy\u27s underwater radiated noise signature was characterized in the central Arctic Ocean during different types of ice-breaking operations. Propulsion modes included transit in variable ice cover, breaking heavy ice with backing-and-ramming maneuvers, and dynamic positioning with the bow thruster in operation. Compared to open-water transit, Healy\u27s noise signature increased approximately 10 dB between 20 Hz and 2 kHz when breaking ice. The highest noise levels resulted while the ship was engaged in backing-and-ramming maneuvers, owing to cavitation when operating the propellers astern or in opposing directions. In frequency bands centered near 10, 50, and 100 Hz, source levels reached 190–200 dB re: 1 μPa at 1 m (full octave band) during ice-breaking operations
Water production in comet 81P/Wild 2 as determined by Herschel/HIFI
The high spectral resolution and sensitivity of Herschel/HIFI allows for the detection of multiple rotational water lines and accurate determinations
of water production rates in comets. In this Letter we present HIFI observations of the fundamental 1_(10)–1_(01) (557 GHz) ortho and 1_(11)–0_(00)
(1113 GHz) para rotational transitions of water in comet 81P/Wild 2 acquired in February 2010. We mapped the extent of the water line emission
with five point scans. Line profiles are computed using excitation models which include excitation by collisions with electrons and neutrals and
solar infrared radiation. We derive a mean water production rate of 1.0 × 10^(28) molecules s^(−1) at a heliocentric distance of 1.61 AU about 20 days
before perihelion, in agreement with production rates measured from the ground using observations of the 18-cm OH lines. Furthermore, we
constrain the electron density profile and gas kinetic temperature, and estimate the coma expansion velocity by fitting the water line shapes
Comment on "Deuterium--tritium fusion reactors without external fusion breeding" by Eliezer et al
Inclusion of inverse Compton effects in the calculation of
deuterium-deuterium burn under the extreme conditions considered by Eliezer et
al. [Phys. Lett. A 243 (1998) 298] are shown to decrease the maximum burn
temperature from about 300 keV to only 100--150 keV. This decrease is such that
tritium breeding by the DD --> T + p reaction is not sufficient to replace the
small amount of tritium that is initially added to the deuterium plasma in
order to trigger ignition at less than 10 keV.Comment: 6 pages, 1 tabl
Compilability of Abduction
Abduction is one of the most important forms of reasoning; it has been
successfully applied to several practical problems such as diagnosis. In this
paper we investigate whether the computational complexity of abduction can be
reduced by an appropriate use of preprocessing. This is motivated by the fact
that part of the data of the problem (namely, the set of all possible
assumptions and the theory relating assumptions and manifestations) are often
known before the rest of the problem. In this paper, we show some complexity
results about abduction when compilation is allowed
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