34,480 research outputs found
Next to leading order non Fermi liquid corrections to the neutrino emissivity and cooling of the neutron star
In this work we derive the expressions of the neutrino mean free path(MFP)
and emissivity with non Fermi liquid corrections up to next to leading
order(NLO) in degenerate quark matter. The calculation has been performed both
for the absorption and scattering processes. Subsequently the role of these NLO
corrections on the cooling of the neutron star has been demonstrated. The
cooling curve shows moderate enhancement compared to the leading order(LO)
non-Fermi liquid result. Although the overall correction to the MFP and
emissivity are larger compared to the free Fermi gas, the cooling behavior does
not alter significantly.Comment: 8 pages, 8 figures, references added, matches published versio
The pale evidence for treatment of iron-deficiency anaemia in older people
Funding The authors have received funding to carry out a pilot RCT on management of IDA in older people from the Chief Scientist Office, Scotland.Peer reviewedPostprin
Reionization constraints on primordial magnetic fields
We study the impact of the extra density fluctuations induced by primordial
magnetic fields on the reionization history in the redshift range: . We perform a comprehensive MCMC physical analysis allowing the variation
of parameters related to primordial magnetic fields (strength, , and
power-spectrum index ), reionization, and
CDM cosmological model. We find that magnetic field strengths in the
range: nG (for nearly scale-free power spectra) can
significantly alter the reionization history in the above redshift range and
can relieve the tension between the WMAP and quasar absorption spectra data.
Our analysis puts upper-limits on the magnetic field strength nG (95 % c.l.) for , respectively. These represent the strongest magnetic field constraints
among those available from other cosmological observables.Comment: Accepted for publication in MNRAS; 9 pages, 6 figure
Two photon annihilation operators and squeezed vacuum
Inverses of the harmonic oscillator creation and annihilation operators by their actions on the number states are introduced. Three of the two photon annihilation operators, viz., a(sup +/-1)a, aa(sup +/-1), and a(sup 2), have normalizable right eigenstates with nonvanishing eigenvalues. The eigenvalue equation of these operators are discussed and their normalized eigenstates are obtained. The Fock state representation in each case separates into two sets of states, one involving only the even number states while the other involving only the odd number states. It is shown that the even set of eigenstates of the operator a(sup +/-1)a is the customary squeezed vacuum S(sigma) O greater than
Demonstration of automated proximity and docking technologies
An autodock was demonstrated using straightforward techniques and real sensor hardware. A simulation testbed was established and validated. The sensor design was refined with improved optical performance and image processing noise mitigation techniques, and the sensor is ready for production from off-the-shelf components. The autonomous spacecraft architecture is defined. The areas of sensors, docking hardware, propulsion, and avionics are included in the design. The Guidance Navigation and Control architecture and requirements are developed. Modular structures suitable for automated control are used. The spacecraft system manager functions including configuration, resource, and redundancy management are defined. The requirements for autonomous spacecraft executive are defined. High level decisionmaking, mission planning, and mission contingency recovery are a part of this. The next step is to do flight demonstrations. After the presentation the following question was asked. How do you define validation? There are two components to validation definition: software simulation with formal and vigorous validation, and hardware and facility performance validated with respect to software already validated against analytical profile
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The influence of physical and chemical linkage on the properties of nanocomposites
It has been shown by several groups that the mechanical and electrical behavior of composites changes quite substantially, and often beneficially, when the filler particle size is less than 100 nm in diameter. There is also good reason to believe that the interface between the embedded particulates and the polymer matrix holds the key to understanding the bulk phenomena observed. Materials based on an SiO2-polyolefin system have been formulated with functionalized particulates so as to affect the physical and chemical linkages. The agents used to achieve this include amino-silane, hexamethyl-disilazane and triethoxyvinylsilane. The emerging picture of the interface is supported by detailed dielectric spectroscopy and internal space charge assessment. The nature of the internal structure has been related to the bulk properties observed such as the breakdown strength, voltage endurance, and the measurement of internal charges resulting from interfacial polarization
Potential algebra approach to position dependent mass Schroedinger equation
It is shown that for a class of position dependent mass Schroedinger equation
the shape invariance condition is equivalent to a potential symmetry algebra.
Explicit realization of such algebras have been obtained for some shape
invariant potentials
Higher dimensional models of light Majorana neutrinos confronted by data
We discuss experimental and observational constraints on certain models of
higher dimensional light Majorana neutrinos. Models with flavor blind
brane-bulk couplings plus three or four flavor diagonal light Majorana
neutrinos on the brane, with subsequent mixing induced solely by the
Kaluza-Klein tower of states, are found to be excluded by data on the
oscillations of solar, atmospheric and reactor neutrinos, taken together with
the WMAP upper bound on the sum of neutrino masses. Extra dimensions, if
relevant to neutrino mixing, need to discriminate between neutrino flavors.Comment: 5 pages, Revtex4, 2 PS figures. Fig. 2a and 2b from earlier version
are now combined into one figure. Minor modifications in the text. References
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