25,926 research outputs found
An optical method for determining level in two-phase cryogenic fluids
A method was evaluated to measure the liquid-gas and the liquid-slush interfaces in two-phase cryogen systems using optical means. This method makes use of the attenuation of a directed light beam caused by the difference in the index of refraction between the solid particles and the surrounding liquid. Preliminary experimental results obtained in slush nitrogen are shown. The possibility of extending this technique to include a measure of solid fraction is also discussed
TiCl4 as a source of TiO2 particles for laser anemometry measurements in hot gas
A method of reacting TiCl4 with water saturated gaseous nitrogen (GN2) at the entrance into a high temperature gas flow is described. The TiO2 particles formed are then entrained in the gas flow and used as seed particles for making laser anemometry (LA) measurements of the flow velocity distribution in the hot gas. Scanning electron microscope photographs of the TiO2 particles are shown. Data rate of the LA processor was measured to determine the amount of TiO2 formed. The TiCl4 and mixing gas flow diagram is shown. This work was performed in an open jet burner
High Field Studies of Superconducting Fluctuations in High-T_c Cuprates: Evidence for a Small Gap distinct from the Large Pseudogap
We have used pulsed magnetic fields up to 60Tesla to suppress the
contribution of superconducting fluctuations(SCF)to the conductivity above Tc
in a series of YBa2Cu3O6+x from the deep pseudogapped state to slight
overdoping. Accurate determinations of the SCF conductivity versus temperature
and magnetic field have been achieved. Their joint quantitative analyses with
respect to Nernst data allow us to establish that thermal fluctuations
following the Ginzburg-Landau(GL) scheme are dominant for nearly optimally
doped samples. The deduced coherence length xi(T) is in perfect agreement with
a gaussian (Aslamazov-Larkin) contribution for 1.01Tc<T<1.2Tc. A phase
fluctuation contribution might be invoked for the most underdoped samples in a
T range which increases when controlled disorder is introduced by electron
irradiation. For all dopings we evidence that the fluctuations are highly
damped when increasing T or H. The data permits us to define a field Hc^prime
and a temperature Tc^prime above which the SCF are fully suppressed. The
analysis of the fluctuation magnetoconductance in the GL approach allows us to
determine the critical field Hc2(0). The actual values of Hc^prime(0) and
Hc2(0) are found quite similar and both increase with hole doping. These
depairing fields, which are directly connected to the magnitude of the SC gap,
do therefore follow the Tc variation which is at odds with the sharp decrease
of the pseudogap T* with increasing hole doping. This is on line with our
previous evidence that T* is not the onset of pairing. We finally propose a
three dimensional phase diagram including a disorder axis, which allows to
explain most peculiar observations done so far on the diverse cuprate families.Comment: revised version, to be published in Physical Review B. Small
modifications have been done in paragraphs VI.A and VI
Laser anemometry: A status report
A laser anemometer system is being developed for the warm turbine facility as part of the HOST program. The system will be built using results obtained from the analytical and experimental research program. The status report of the laser anemometry applications research effort is presented. The designs for the turbine casing, the windows, and the positioning system were completed. A block diagram of the laser anemometer system, signal processing scheme, and computer system is given
The Role of Relapse Prevention and Goal Setting in Training Transfer Enhancement
This article reviews the effect of two post-training transfer interventions (relapse prevention [RP] and goal setting [GS]) on trainees’ ability to apply skills gained in a training context to the workplace. Through a review of post-training transfer interventions literature, the article identifies a number of key issues that remain unresolved or underexplored, for example, the inconsistent results on the impact of RP on transfer of training, the lack of agreement on which GS types are more efficient to improve transfer performance, the lack of clarity about the distinction between RP and GS, and the underlying process through which these two post-training transfer interventions influence transfer of training. We offer some recommendations to overcome these problems and also provide guidance for future research on transfer of training
Growth modulation by means of anterior tethering resulting in progressive correction of juvenile idiopathic scoliosis: A case report
Electroweak Supersymmetry with an Approximate U(1)_PQ
A predictive framework for supersymmetry at the TeV scale is presented, which
incorporates the Ciafaloni-Pomarol mechanism for the dynamical determination of
the \mu parameter of the MSSM. It is replaced by (\lambda S), where S is a
singlet field, and the axion becomes a heavy pseudoscalar, G, by adding a mass,
m_G, by hand. The explicit breaking of Peccei-Quinn (PQ) symmetry is assumed to
be sufficiently weak at the TeV scale that the only observable consequence is
the mass m_G. Three models for the explicit PQ breaking are given; but the
utility of this framework is that the predictions for all physics at the
electroweak scale are independent of the particular model for PQ breaking. Our
framework leads to a theory similar to the MSSM, except that \mu is predicted
by the Ciafaloni-Pomarol relation, and there are light, weakly-coupled states
in the spectrum. The production and cascade decay of superpartners at colliders
occurs as in the MSSM, except that there is one extra stage of the cascade
chain, with the next-to-LSP decaying to its "superpartner" and \tilde{s},
dramatically altering the collider signatures for supersymmetry. The framework
is compatible with terrestrial experiments and astrophysical observations for a
wide range of m_G and . If G is as light as possible, 300 keV < m_G < 3 MeV,
it can have interesting effects on the radiation energy density during the
cosmological eras of nucleosynthesis and acoustic oscillation, leading to
predictions for N_{\nu BBN} and N_{\nu CMB} different from 3.Comment: 45 pages, 2 colour figures, a reference added, minor correction
Negligence—Proximate Cause; Statutes—Amendments—Constitutional Requirement; Workmen\u27s Compensation—Employees Within Act
Short summaries of recent cases
Measuring the Fraction of Obscured Quasars by the Infrared Luminosity of Unobscured Quasars
Recent work has suggested that the fraction of obscured AGN declines with
increasing luminosity, but it has been difficult to quantify this trend. Here,
we attempt to measure this fraction as a function of luminosity by studying the
ratio of mid-infrared to intrinsic nuclear bolometric luminosity in unobscured
AGN. Because the mid-infrared is created by dust reprocessing of shorter
wavelength nuclear light, this ratio is a diagnostic of f_obsc, the fraction of
solid angle around the nucleus covered by obscuring matter. In order to
eliminate possible redshift-dependences while also achieving a large dynamic
range in luminosity, we have collected archival 24 micron MIPS photometry from
objects with z~1 in the Sloan Digital Sky Survey (SDSS), the Great
Observatories Origins Deep Survey (GOODS) and the Cosmic Evolution Survey
(COSMOS). To measure the bolometric luminosity for each object, we used
archival optical data supplemented by GALEX data. We find that the mean ratio
of 24 microns to bolometric luminosity decreases by a factor of ~3 in the
L_bol=10^44-3x10^47 ergs s^-1 range, but there is also a large scatter at
constant L_bol. Using radiation transfer solutions for model geometries, we
show how the IR/bolometric ratio relates to f_obsc and compare these values
with those obtained obtained from samples of X-ray selected AGN. Although we
find approximate agreement, our method indicates somewhat higher values of
f_obsc, particularly in the middle range of luminosities, suggesting that there
may be a significant number of heavily obscured AGN missed by X-ray surveys.Comment: ApJ, in press. 10 pages in emulateapj style, 4 figures, 3 table
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