20,387 research outputs found
Nuclear Quasi-Elastic Electron Scattering Limits Nucleon Off-Mass Shell Properties
The use of quasi-elastic electron nucleus scattering is shown to provide
significant constraints on models of the proton electromagnetic form factor of
off-shell nucleons. Such models can be constructed to be consistent with
constraints from current conservation and low-energy theorems, while also
providing a contribution to the Lamb shift that might potentially resolve the
proton radius puzzle in muonic hydrogen. However, observations of quasi-elastic
scattering limit the overall strength of the off-shell form factors to values
that correspond to small contributions to the Lamb shift.Comment: 11 pages, 2 figures. Resubmission to improve the clarity, and correct
possible misconception
Ultra high speed image processing techniques
Packaging techniques for ultra high speed image processing were developed. These techniques involve the development of a signal feedthrough technique through LSI/VLSI sapphire substrates. This allows the stacking of LSI/VLSI circuit substrates in a 3 dimensional package with greatly reduced length of interconnecting lines between the LSI/VLSI circuits. The reduced parasitic capacitances results in higher LSI/VLSI computational speeds at significantly reduced power consumption levels
A detailed X-ray investigation of zeta Puppis IV. Further characterization of the variability
Previously, the X-ray emission of zeta Puppis was found to be variable with
light curves harbouring "trends" with a typical timescale longer than the
exposure length. The origin of these changes was proposed to be linked to
large-scale structures in the wind, but further characterization of the
variability at high energies was needed. Since then, a number of new X-ray
observations have become available. Furthermore, a cyclic behaviour with a
1.78d period was identified in long optical photometric runs, which is thought
to be associated with the launching mechanism of large-scale wind structures.
We analysed these new X-ray data, revisited the old data, and compared X-ray
with optical data, including when simultaneous. We found that the behaviour in
X-rays cannot be explained in terms of a perfect clock because the amplitude
and shape of its variations change with time. For example, zeta Puppis was much
more strongly variable between 2007 and 2011 than before and after this
interval. Comparing the X-ray spectra of the star at maximum and minimum
brightness yields no compelling difference beyond the overall flux change: the
temperatures, absorptions, and line shapes seem to remain constant, well within
errors. The only common feature between X-ray datasets is that the variation
amplitudes appear maximum in the medium (0.6-1.2keV) energy band. Finally, no
clear and coherent correlation can be found between simultaneous X-ray and
optical data. Only a subgroup of observations may be combined coherently with
the optical period of 1.78d, although the simultaneous optical behaviour is
unknown. The currently available data do not reveal any obvious, permanent, and
direct correlation between X-ray and optical variations. The origin of the
X-ray variability therefore still needs to be ascertained, highlighting the
need for long-term monitoring in multiwavelengths, i.e. X-ray, UV, and optical.Comment: accepted for publication by A&
SUMOylation determines the voltage required to activate cardiac IKs channels.
IKs channels open in response to depolarization of the membrane voltage during the cardiac action potential, passing potassium ions outward to repolarize ventricular myocytes and end each beat. Here, we show that the voltage required to activate IKs channels depends on their covalent modification by small ubiquitin-like modifier (SUMO) proteins. IKs channels are comprised of four KCNQ1 pore-forming subunits, two KCNE1 accessory subunits, and up to four SUMOs, one on Lys424 of each KCNQ1 subunit. Each SUMO shifts the half-maximal activation voltage (V1/2) of IKs ∼ +8 mV, producing a maximal +34-mV shift in neonatal mouse cardiac myocytes or Chinese hamster ovary (CHO) cells expressing the mouse or human subunits. Unexpectedly, channels formed without KCNE1 carry at most two SUMOs despite having four available KCNQ1-Lys424 sites. SUMOylation of KCNQ1 is KCNE1 dependent and determines the native attributes of cardiac IKs in vivo
Further experimental tests for simple relations between unpolarized and polarized quark parton distributions
Some simple relations between unpolarized and polarized quark parton
distributions have direct experimental consequences which will be presented
here. In particular, we will see that it is possible to relate the deep
inelastic structure functions and , both for proton and deuteron, in
fair agreement with experimental data.Comment: 5 pages, in Latex, 3 figure
Enforcement of Occupational Safety and Health Laws in Virginia: A New Beginning
Preempted in 1972 from enforcing its laws and regulations pertaining to employee safety and health by the Occupational Safety and Health Act of 1970 (OSHA), Virginia resumed enforcement activities on January 1, 1977, implementing, pursuant to the provisions of the Federal Act, a unique developmental State Plan. Virginia\u27s resumption of enforcement activity in the area of job safety and health culminated a difficult four-year effort by the legislative and executive branches of Virginia government to gain recognition from the United States Department of Labor that her regulations and the method for enforcing the regulations were at least as effective as the provisions of the Federal Act
Estimating the Short-term Effects of an Increase in Par on Reel Slot Performance
Data from a US hotel casino are analyzed to examine the validity of a controversial theory holding that reel slot players are unable to perceive substantial increases in par (i.e., a hidden price). The results of a multiple regression analysis support this theory. A 50% increase in the pars of a $5.00 reel sample, failed to significantly affect the performance of these games. The control-group games featured 5.0% pars, while the experiment-group pars were set at 7.5%. Descriptive statistics show that the theoretical win per unit actually increased at the 7.5% par. The strategy behind the theory is to obtain bankrolls before players decide to gamble elsewhere. As player acquisition costs are rapidly growing, casino executives wish to maximize their return on this investment and increase their share of wallet. For those operating casinos in markets with easily accessible competitors, this study is rich with managerial and strategic implications
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