9,639 research outputs found
System for improving measurement accuracy of transducer by measuring transducer temperature and resistance change using thermoelectric voltages
A constant current loop measuring system measures a property including the temperature of a sensor responsive to an external condition being measured. The measuring system includes thermocouple conductors connected to the sensor, sensing first and second induced voltages responsive to the external condition. In addition, the measuring system includes a current generator and reverser generating a constant current, and supplying the constant current to the thermocouple conductors in forward and reverse directions generating first and second measured voltages, and a determining unit receiving the first and second measured voltages from the current generator and reverser, and determining the temperature of the sensor responsive to the first and second measured voltages
Time-Resolved Ultraviolet Observations of the Globular Cluster X-ray Source in NGC 6624: The Shortest Known Period Binary System
Using the Faint Object Spectrograph (FOS) aboard the Hubble Space Telescope,
we have obtained the first time-resolved spectra of the King et al.
ultraviolet-bright counterpart to the 11-minute binary X-ray source in the core
of the globular cluster NGC 6624. This object cannot be readily observed in the
visible, even from HST, due to a much brighter star superposed <0.1'' distant.
Our FOS data show a highly statistically significant UV flux modulation with a
period of 11.46+-0.04 min, very similar to the 685 sec period of the known
X-ray modulation, definitively confirming the association between the King et
al. UV counterpart and the intense X-ray source. The UV amplitude is very large
compared with the observed X-ray oscillations: X-ray variations are generally
reported as 2-3% peak-to-peak, whereas our data show an amplitude of about 16%
in the 126-251 nm range. A model for the system by Arons & King predicts
periodic UV fluctuations in this shortest-known period binary system, due to
the cyclically changing aspect of the X-ray heated face of the secondary star
(perhaps a very low mass helium degenerate). However, prior to our
observations, this predicted modulation has not been detected. Employing the
Arons & King formalism, which invokes a number of different physical
assumptions, we infer a system orbital inclination 35deg<i<50 deg. Amongst the
three best-studied UV/optical counterparts to the intense globular cluster
X-ray sources, two are now thought to consist of exotic double-degenerate
ultrashort period binary systems.Comment: 10 pages including 2 figures in Latex (AASTeX 4.0). Accepted for
publication in vol. 482 (1997 June 10 issue) of The Astrophysical Journal
(Letters
An Exploratory Survey of Money Boys and HIV Transmission Risk in Jilin Province, PR China
This report represents the first exploratory study of Chinese men who provide commercial sex services to other men ("money boys") in Jilin Province, People's Republic of China, through a convenience sample drawn from Changchun and Jilin City. A total of 86 active money boy participants (Changchun, n = 49; Jilin City, n = 37) were surveyed concerning background and demographics, basic HIV transmission knowledge, and sexual practices. The survey indicated that while Jilin Province money boy behavior matches other studies concerning propensity to high risk behavior and significant bridging potential, the Jilin money boys, unlike previous studies, exhibited a high level of basic HIV/AIDS transmission knowledge. In spite of this level of knowledge, none of the participants reported always using a condom in their sexual activities. They also exhibited a high level of awareness of voluntary counseling and testing available in the province, yet relatively few had availed themselves of these services. These preliminary findings will be used as a baseline and springboard for continuing study in the Jilin Province money boy community. Even now, however, it is becoming clear that the dynamics of male commercial sex work may vary greatly depending upon local influences, and will necessitate that future interventions are highly tailored to area-specific circumstances
UC-268 Buggy - Price Scraper Application
Buggy is a desktop price scraper application that finds the best deals for users across several major retailers. Retailers include Amazon, Costco, Target, Walmart, and eBay. It simplifies bargain hunting by condensing product information from multiple websites into one, convenient place. Users can save products for future access, track search history, and compare search results with tabs for navigation. When they are ready to buy, they can simply click on the buy button and are directed to the vendor\u27s page to check out
Determining Training Needs for Cloud Infrastructure Investigations using I-STRIDE
As more businesses and users adopt cloud computing services, security
vulnerabilities will be increasingly found and exploited. There are many
technological and political challenges where investigation of potentially
criminal incidents in the cloud are concerned. Security experts, however, must
still be able to acquire and analyze data in a methodical, rigorous and
forensically sound manner. This work applies the STRIDE asset-based risk
assessment method to cloud computing infrastructure for the purpose of
identifying and assessing an organization's ability to respond to and
investigate breaches in cloud computing environments. An extension to the
STRIDE risk assessment model is proposed to help organizations quickly respond
to incidents while ensuring acquisition and integrity of the largest amount of
digital evidence possible. Further, the proposed model allows organizations to
assess the needs and capacity of their incident responders before an incident
occurs.Comment: 13 pages, 3 figures, 3 tables, 5th International Conference on
Digital Forensics and Cyber Crime; Digital Forensics and Cyber Crime, pp.
223-236, 201
Looking back at superfluid helium
A few years after the discovery of Bose Einstein condensation in several
gases, it is interesting to look back at some properties of superfluid helium.
After a short historical review, I comment shortly on boiling and evaporation,
then on the role of rotons and vortices in the existence of a critical velocity
in superfluid helium. I finally discuss the existence of a condensate in a
liquid with strong interactions, and the pressure variation of its superfluid
transition temperature.Comment: Conference "Bose Einstein Condensation", Institut henri Poincare,
Paris, 29 march 200
Attractor states and infrared scaling in de Sitter space
The renormalized expectation value of the energy-momentum tensor for a scalar
field with any mass m and curvature coupling xi is studied for an arbitrary
homogeneous and isotropic physical initial state in de Sitter spacetime. We
prove quite generally that has a fixed point attractor behavior at
late times, which depends only on m and xi, for any fourth order adiabatic
state that is infrared finite. Specifically, when m^2 + xi R > 0,
approaches the Bunch-Davies de Sitter invariant value at late times,
independently of the initial state. When m = xi = 0, it approaches instead the
de Sitter invariant Allen-Folacci value. When m = 0 and xi \ge 0 we show that
this state independent asymptotic value of the energy-momentum tensor is
proportional to the conserved geometrical tensor (3)H_{ab}, which is related to
the behavior of the quantum effective action of the scalar field under global
Weyl rescaling. This relationship serves to generalize the definition of the
trace anomaly in the infrared for massless, non-conformal fields. In the case
m^2 + xi R = 0, but m and xi separately different from zero, grows
linearly with cosmic time at late times. For most values of m and xi in the
tachyonic cases, m^2 + xi R grows exponentially at late cosmic
times for all physically admissable initial states.Comment: 30 pages, 6 figures, 46 kB tar.gz fil
Creation of vortices in a Bose-Einstein condensate by a Raman technique
We propose a method for taking a Bose-Einstein condensate in the ground trap
state simultaneously to a different atomic hyperfine state and to a vortex trap
state. This can be accomplished through a Raman scheme in which one of the two
copropagating laser beams has a higher-order Laguerre-Gaussian mode profile.
Coefficients relating the beam waist, pulse area, and trap potentials for a
complete transfer to the m = 1 vortex are calculated for a condensate in the
non-interacting and strongly interacting regimes.Comment: RevTex, 4 pages, 2 PostScript figure
Laboratory Evaluations of Stabilized Flue Gas Desulfurization Sludge (Scrubber Sludge) and Aggregate Mixtures
The Kentucky Transportation Research Program has completed a laboratory study involving the use of flue gas desulfurization sludge (scrubber sludge) for potential application as a highway subbase and/or embankment material. Scrubber sludge is a waste produet formed when fly ash (and other residue) is combined with a lime dust slurry filter cake and stabilized with quicklime (calcium oxide). Samples of stockpiled (field) sludge and dry sludge components were obtained from the Robert Reid Station (Big Rivers Electric Corporation) in Sebree, Kentuclty. Dry sludge components (fly ash, filter cake, and quicklime) were uaed to prepare sludge samples in the laboratory, allowing a higher degree of quality control for compariaon purposes. Mixtures for testing included scrubber sludge, scrubber sludge with pond ash (bottom ash), and scrubber sludge with dense graded limestone aggregate (DGA). One objective of laboratory analyses was the determination of optimum mixture proportions. A mixture of 20-percent scrubber sludge and 80-percent pond ash was determined to be the optimum design mix. That mixture showed significant strength gain with curing and had a static-chord modulus of elasticity approximately 118 times the compressive strength. Strength and modulus tests indicated that mixtures of scrubber sludge and pond ash were superior to mixtures of scrubber sludge and DGA. The scope of the study, however, did not permit complete explanation of these observations. An economic study showed that scrubber sludge with pond ash can be used economically as a highway subbase material, especially on low-fatigue roads, by partially replacing more expensive pavement layers. Triaxial tests and computer simulations indicated that scrubber sludge could be used as an embankment material in some applications. However, this would be economical only if suitable fill material was not available at or near the fill site
Comparative study of complex N- and O-bearing molecules in hot molecular cores
We have observed several emission lines of two Nitrogen-bearing (C2H5CN and
C2H3CN) and two Oxygen-bearing (CH3OCH3 and HCOOCH3) molecules towards a sample
of well-known hot molecular cores (HMCs) in order to check whether the chemical
differentiation seen in the Orion-HMC and W3(H_2O) between O- and N-bearing
molecules is a general property of HMCs. With the IRAM-30m telescope we have
observed 12 HMCs in 21 bands, centered at frequencies from 86250 to 258280 MHz.
The rotational temperatures obtained range from ~100 to ~150 K in these HMCs.
Single Gaussian fits performed to unblended lines show a marginal difference in
the line peak velocities of the C2H5CN and CH3OCH3 lines, indicating a possible
spatial separation between the region traced by the two molecules. On the other
hand, neither the linewidths nor the rotational temperatures and column
densities confirm such a result. By comparing the abundance ratio of the pair
C2H5CN/C2H3CN with the predictions of theoretical models, we derive that the
age of our cores ranges between 3.7 and 5.9x10^{4} yrs. The abundances of
C2H5CN and C2H3CN are strongly correlated, as expected from theory which
predicts that C2H3CN is formed through gas phase reactions involving C2H5CN. A
correlation is also found between the abundances of C2H3CN and CH3OCH3, and
C2H5CN and CH3OCH3. In all tracers the fractional abundances increase with the
H_2 column density while they are not correlated with the gas temperature.Comment: Accepted for publication in A&A, 56 page
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