3,063 research outputs found
Nimbus Telemetry
Nimbus satellite - pulse-code-modulated telemetry subsyte
Deep Space Network utilization for flight projects, calendar year 1981
A report on the utilization of the Deep Space Network during calendar year 1981 in support of all flight projects is presented. The network expended 63% of its total capability in support of Space Flight projects
Thermodynamic constraints on fluctuation phenomena
The relationships between reversible Carnot cycles, the absence of perpetual
motion machines and the existence of a non-decreasing, globally unique entropy
function forms the starting point of many textbook presentations of the
foundations of thermodynamics. However, the thermal fluctuation phenomena
associated with statistical mechanics has been argued to restrict the domain of
validity of this basis of the second law of thermodynamics. Here we demonstrate
that fluctuation phenomena can be incorporated into the traditional
presentation, extending, rather than restricting, the domain of validity of the
phenomenologically motivated second law. Consistency conditions lead to
constraints upon the possible spectrum of thermal fluctuations. In a special
case this uniquely selects the Gibbs canonical distribution and more generally
incorporates the Tsallis distributions. No particular model of microscopic
dynamics need be assumed.Comment: 12 pages, 24 figure
Heat transfer between nanoparticles: Thermal conductance for near-field interactions
We analyze the heat transfer between two nanoparticles separated by a
distance lying in the near-field domain in which energy interchange is due to
Coulomb interactions. The thermal conductance is computed by assuming that the
particles have charge distributions characterized by fluctuating multipole
moments in equilibrium with heat baths at two different temperatures. This
quantity follows from the fluctuation-dissipation theorem (FDT) for the
fluctuations of the multipolar moments. We compare the behavior of the
conductance as a function of the distance between the particles with the result
obtained by means of molecular dynamics simulations. The formalism proposed
enables us to provide a comprehensive explanation of the marked growth of the
conductance when decreasing the distance between the nanoparticles
Slow relaxation of conductance of amorphous hopping insulators
We discuss memory effects in the conductance of hopping insulators due to
slow rearrangements of structural defects leading to formation of polarons
close to the electron hopping states. An abrupt change in the gate voltage and
corresponding shift of the chemical potential change populations of the hopping
sites, which then slowly relax due to rearrangements of structural defects. As
a result, the density of hopping states becomes time dependent on a scale
relevant to rearrangement of the structural defects leading to the excess time
dependent conductivity.Comment: 6 pages, 1 figur
Dynamical description of vesicle growth and shape change
We systematize and extend the description of vesicle growth and shape change
using linear nonequilibrium thermodynamics. By restricting the study to shape
changes from spheres to axisymmetric ellipsoids, we are able to give a
consistent formulation which includes the lateral tension of the vesicle
membrane. This allows us to generalize and correct a previous calculation. Our
present calculations suggest that, for small growing vesicles, a prolate
ellipsoidal shape should be favored over oblate ellipsoids, whereas for large
growing vesicles oblates should be favored over prolates. The validity of this
prediction is examined in the light of the various assumptions made in its
derivation.Comment: 6 page
Hard exclusive electroproduction of decuplet baryons in the large N_c limit
The cross sections and transverse spin asymmetries in the hard exclusive
electroproduction of decuplet baryons are calculated in the large N_c limit and
found to be comparable to that of octet baryons. Large N_c selection rules for
the production amplitudes are derived, leading to new sensitive tests of the
spin aspects of the QCD chiral dynamics both in the nonstrange and strange
sectors. Importance of such studies for the reliable extraction of the pion
form factor from pion electroproduction is explained.Comment: 4 pages, 3 figure
Decreased ovarian reserve, dysregulation of mitochondrial biogenesis, and increased lipid peroxidation in female mouse offspring exposed to an obesogenic maternal diet.
Maternal diet during pregnancy influences the later life reproductive potential of female offspring. We investigate the molecular mechanisms underlying the depletion of ovarian follicular reserve in young adult females following exposure to obesogenic diet in early life. Furthermore, we explore the interaction between adverse maternal diet and postweaning diet in generating reduced ovarian reserve. Female mice were exposed to either maternal obesogenic (high fat/high sugar) or maternal control dietin uteroand during lactation, then weaned onto either obesogenic or control diet. At 12 wk of age, the offspring ovarian reserve was depleted following exposure to maternal obesogenic diet (P< 0.05), but not postweaning obesogenic diet. Maternal obesogenic diet was associated with increased mitochondrial DNA biogenesis (copy numberP< 0.05; transcription factor A, mitochondrial expressionP< 0.05), increased mitochondrial antioxidant defenses [manganese superoxide dismutase (MnSOD)P< 0.05; copper/zinc superoxide dismutaseP< 0.05; glutathione peroxidase 4P< 0.01] and increased lipoxygenase expression (arachidonate 12-lipoxygenaseP< 0.05; arachidonate 15-lipoxygenaseP< 0.05) in the ovary. There was also significantly increased expression of the transcriptional regulator NF-κB (P< 0.05). There was no effect of postweaning diet on any measured ovarian parameters. Maternal diet thus plays a central role in determining follicular reserve in adult female offspring. Our observations suggest that lipid peroxidation and mitochondrial biogenesis are the key intracellular pathways involved in programming of ovarian reserve.-Aiken, C. E., Tarry-Adkins, J. L., Penfold, N. C., Dearden, L., Ozanne, S. E. Decreased ovarian reserve, dysregulation of mitochondrial biogenesis, and increased lipid peroxidation in female mouse offspring exposed to an obesogenic maternal diet.This study was funded jointly by grants from the Academy of Medical Sciences, the Addenbrooke’s Charitable Trust, an Isaac Newton Trust/Wellcome Trust ISSF/University of Cambridge Joint Research Grant and the MRC (MRC_MC_UU_12012/4).This is the final version of the article. It first appeared from the Federation of American Societies for Experimental Biology via http://dx.doi.org/10.1096/fj.15-28080
Ulta-slow relaxation in discontinuous-film based electron glasses
We present field effect measurements on discontinuous 2D thin films which are
composed of a sub monolayer of nano-grains of Au, Ni, Ag or Al. Like other
electron glasses these systems exhibit slow conductance relaxation and memory
effects. However, unlike other systems, the discontinuous films exhibit a
dramatic slowing down of the dynamics below a characteristic temperature .
is typically between 10-50K and is sample dependent. For the
sample exhibits a few other peculiar features such as repeatable conductance
fluctuations in millimeter size samples. We suggest that the enhanced system
sluggishness is related to the current carrying network becoming very dilute in
discontinuous films so that the system contains many parts which are
electrically very weakly connected and the transport is dominated by very few
weak links. This enables studying the glassy properties of the sample as it
transitions from a macroscopic sample to a mesocopic sample, hence, the results
provide new insight on the underlying physics of electron glasses.Comment: 4 pages, 4 figure
Nucleon-nucleon interaction in the Skyrme model
We consider the interaction of two skyrmions in the framework of the sudden
approximation. The widely used product ansatz is investigated. Its failure in
reproducing an attractive central potential is associated with terms that
violate G-parity. We discuss the construction of alternative ans\"atze and
identify a plausible solution to the problem.Comment: 18 pages, 9 figure
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