9,703 research outputs found
Microgravity: A Teacher's Guide With Activities in Science, Mathematics, and Technology
The purpose of this curriculum supplement guide is to define and explain microgravity and show how microgravity can help us learn about the phenomena of our world. The front section of the guide is designed to provide teachers of science, mathematics, and technology at many levels with a foundation in microgravity science and applications. It begins with background information for the teacher on what microgravity is and how it is created. This is followed with information on the domains of microgravity science research; biotechnology, combustion science, fluid physics, fundamental physics, materials science, and microgravity research geared toward exploration. The background section concludes with a history of microgravity research and the expectations microgravity scientists have for research on the International Space Station. Finally, the guide concludes with a suggested reading list, NASA educational resources including electronic resources, and an evaluation questionnaire
First Forcer results on deep-inelastic scattering and related quantities
We present results on the fourth-order splitting functions and coefficient
functions obtained using Forcer, a four-loop generalization of the Mincer
program for the parametric reduction of self-energy integrals. We have computed
the respective lowest three even-N and odd-N moments for the non-singlet
splitting functions and the non-singlet coefficient functions in
electromagnetic and nu+nu(bar) charged-current deep-inelastic scattering, and
the N=2 and N=4 results for the corresponding flavour-singlet quantities.
Enough moments have been obtained for an LLL-based determination of the
analytic N-dependence of the nf^3 and nf^2 parts, respectively, of the singlet
and non-singlet splitting functions. The large-N limit of the latter provides
the complete nf^2 contributions to the four-loop cusp anomalous dimension. Our
results also provide additional evidence of a non-vanishing contribution of
quartic group invariants to the cusp anomalous dimension.Comment: 11 pages, LaTeX (PoS style), 4 eps-figures. To appear in the
proceedings of `Loops & Legs 2016', Leipzig (Germany), April 201
Four-loop results on anomalous dimensions and splitting functions in QCD
We report on recent progress on the flavour non-singlet splitting functions
in perturbative QCD. The~exact four-loop (N^3LO) contribution to these
functions has been obtained in the planar limit of a large number of colours.
Phenomenologically sufficient approximate expressions have been obtained for
the parts not exactly known so far. Both cases include results for the
four-loop cusp and virtual anomalous dimensions which are relevant well beyond
the evolution of non-singlet quark distributions, for which an accuracy of
(well) below 1% has now been been reached.Comment: 11 pages, LaTeX (PoS style), 4 eps-figures. Contribution to the
proceedings of `RADCOR 2017', St. Gilgen (Austria), September 201
Sea flavor content of octet baryons and intrinsic five-quark Fock states
Sea quark contents of the octet baryons are investigated by employing an
extended chiral constituent quark approach, which embodies higher Fock
five-quark components in the baryons wave-functions. The well-known flavor
asymmetry of the nucleon sea , is used as input to predict the
probabilities of , and in the nucleon, ,
and baryons, due to the intrinsic five-quark components in the
baryons wave functions.Comment: 22 page
Anomalous dimensions and splitting functions beyond the next-to-next-to-leading order
We report on recent progress on the splitting functions for the evolution of
parton distributions and related quantities, the (lightlike) cusp anomalous
dimensions, in perturbative QCD. New results are presented for the four-loop
(next-to-next-to-next-to-leading order, N^3LO) contributions to the
flavour-singlet splitting functions and the gluon cusp anomalous dimension. We
present first results, the moments N=2 and N=3, for the five-loop (N^4LO)
non-singlet splitting functions.Comment: 10 pages, LaTeX (PoS style), 3 eps-figures. Contribution to the
proceedings of `Loops & Legs 2018', St. Goar (Germany), April/May 201
Multi-k magnetic structures in USb_{0.9}Te_{0.1} and UAs_{0.8}Se_{0.2} observed via resonant x-ray scattering at the U M4 edge
Experiments with resonant photons at the U M4 edge have been performed on a
sample of USb_{0.9}Te_{0.1}, which has an incommensurate magnetic structure
with k = 0.596(2) reciprocal lattice units. The reflections of the form ,
as observed previously in a commensurate k = 1/2 system [N. Bernhoeft et al.,
Phys. Rev. B 69 174415 (2004)] are observed, removing any doubt that these
occur because of multiple scattering or high-order contamination of the
incident photon beam. They are clearly connected with the presence of a 3k
configuration. Measurements of the reflections from the sample
UAs_{0.8}Se_{0.2} in a magnetic field show that the transition at T* ~ 50 K is
between a low-temperature 2k and high-temperature 3k state and that this
transition is sensitive to an applied magnetic field. These experiments stress
the need for quantitative theory to explain the intensities of these
reflections.Comment: submitted to Phys. Rev.
Black hole puncture initial data with realistic gravitational wave content
We present improved post-Newtonian-inspired initial data for non-spinning
black-hole binaries, suitable for numerical evolution with punctures. We
revisit the work of Tichy et al. [W. Tichy, B. Bruegmann, M. Campanelli, and P.
Diener, Phys. Rev. D 67, 064008 (2003)], explicitly calculating the remaining
integral terms. These terms improve accuracy in the far zone and, for the first
time, include realistic gravitational waves in the initial data. We investigate
the behavior of these data both at the center of mass and in the far zone,
demonstrating agreement of the transverse-traceless parts of the new metric
with quadrupole-approximation waveforms. These data can be used for numerical
evolutions, enabling a direct connection between the merger waveforms and the
post-Newtonian inspiral waveforms.Comment: 13 pages, 7 figures; replaced with published versio
Direct carrier detection by in situ suppression hybridization with cosmid clones of the Duchenne/Becker muscular dystrophy locus
A basic problem in genetic counseling of families with Duchenne/Becker muscular dystrophy (DMD/BMD) concerns the carrier status of female relatives of an affected male. In about 60% of these patients, deletions of one or more exons of the dystrophin gene can be identified. These deletions preferentially include exon 45, which can be detected by multiplex polymerase chain reaction (PCR) and Southern blot analysis of genomic cosmid clones that map to this critical region. As a new approach for definitive carrier detection, we have performed chromosomal in situ suppression (CISS) hybridization with these cosmid clones in female relatives of four unrelated patients. In normal females, most metaphases showed signals on both×chromosomes, whereas only one×chromosome was labeled in carriers. Our results demonstrate that CISS hybridization can define the carrier status in female relatives of DMD patients exhibiting a deletion in the dystrophin gene
Screening and Anti-Screening Effects in J/psi Production on Nuclei
The nuclear effects in J/psi hadro- and electroproduction on nuclei are
considered in framework of reggeon approach. It is shown that screening regime
which holds for electroproduction at x_F > 0.7 and for hadroproduction at x_F >
-(0.3-0.4) is changed with anti-screening regime for smaller x_F values.Comment: 6 pages, 6 figures. Small changes in wordin
Fidelity for displaced squeezed states and the oscillator semigroup
The fidelity for two displaced squeezed thermal states is computed using the
fact that the corresponding density operators belong to the oscillator
semigroup.Comment: 3 pages, REVTEX, no figures, submitted to Journal of Physics A, May
5, 199
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