34,045 research outputs found
Development and evaluation of the elastic recovery concept for expandable space structures
Elastic recovery of expandable space structure
Neutrino emission rates in highly magnetized neutron stars revisited
Magnetars are a subclass of neutron stars whose intense soft-gamma-ray bursts
and quiescent X-ray emission are believed to be powered by the decay of a
strong internal magnetic field. We reanalyze neutrino emission in such stars in
the plausibly relevant regime in which the Landau band spacing of both protons
and electrons is much larger than kT (where k is the Boltzmann constant and T
is the temperature), but still much smaller than the Fermi energies. Focusing
on the direct Urca process, we find that the emissivity oscillates as a
function of density or magnetic field, peaking when the Fermi level of the
protons or electrons lies about 3kT above the bottom of any of their Landau
bands. The oscillation amplitude is comparable to the average emissivity when
the Landau band spacing mentioned above is roughly the geometric mean of kT and
the Fermi energy (excluding mass), i. e., at fields much weaker than required
to confine all particles to the lowest Landau band. Since the density and
magnetic field strength vary continuously inside the neutron star, there will
be alternating surfaces of high and low emissivity. Globally, these
oscillations tend to average out, making it unclear whether there will be any
observable effects.Comment: 7 pages, 2 figures; accepted for publication in Astronomy &
Astrophysic
INVESTIGATING THE APPLICATION OF SERVICE MODULARISATION IN AN INDUSTRY: - “A CASE STUDY OF A MOBILE OPERATOR IN SIERRA LEONE (AIRTEL) AND A MONEY TRANSFER SERVICE IN THE UNITED KINGDOM (WESTERN UNION)”
Abstract
There is an increasing trend in the need for services, and organisations are now moving towards modularisation of their services for efficiency, competitive advantage and to satisfy their customers. Modularisation activities focuses on standardisation, customisation and the reduction of complexity in its system to achieve efficiency, cost minimisation and better service for business growth.
The main objective of this study is to examine how theory and practice relates; which involves bringing out concepts of modularity from literatures and examine practical cases in the service industry.
Interest in the field of modularity is emerging, in order to discover how the implementation of modularity can add value to research and practical application. Therefore, this dissertation seeks to arrive at strategic decisions that should be considered in the implementation of modularisation and identifying the factors that influences the implementation of modularisation in a money transfer service. To achieve this, two case studies were selected, a Mobile Money Transfer Service System in Sierra Leone and the Western Union Money Transfer Service in the United Kingdom.
According to the results the application of modularisation in a service organisation can enhance service efficiency, customers’ satisfaction and contributes greatly in business development by gaining competitive advantage and increase in profit
Spectra of Unsteady Wind Models of Gamma-Ray Bursts
We calculate the spectra expected from unsteady relativistic wind models of
gamma-ray bursts, suitable for events of arbitrary duration. The spectral
energy distribution of the burst is calculated over photon energies spanning
from eV to TeV, for a range of event durations and variability timescales. The
relative strength of the emission at different wavelengths can provide valuable
information on the particle acceleration, radiation mechanisms and the possible
types of models.Comment: 10 pages, 2 postscript figures included, uses aaspp4.sty. Accepted
for publication in the Astrophysical Journal Letters. Also available at
http://www.astro.psu.edu/users/hara/Preprints/xxx_sub.p
Characterisation of Float Rocks at Ireson Hill, Gale Crater
Float rocks discovered by surface missions on Mars have given unique insights into the sedimentary, diagenetic and igneous processes that have operated throughout the planets history. In addition, Gale sedimentary rocks, both float and in situ, record a combination of source compositions and diagenetic overprints. We examine a group of float rocks that were identified by the Mars Science Laboratory missions Curiosity rover at the Ireson Hill site, circa. sol 1600 using ChemCam LIBS, APXS and images from the MastCam, Mars Hand Lens Imager (MAHLI) and ChemCam Remote Micro-Imager (RMI) cameras. Geochemical data provided by the APXS and ChemCam instruments allow us to compare the compositions of these rocks to known rock types from Gale crater, as well as elsewhere on Mars. Ireson Hill is a 15 m long butte in the Murray formation with a dark cap-ping unit with chemical and stratigraphic consistency with the Stimson formation. A total of 6 float rocks have been studied on the butte
Field dependent anisotropy change in a supramolecular Mn(II)-[3x3] grid
The magnetic anisotropy of a novel Mn(II)-[3x3] grid complex was investigated
by means of high-field torque magnetometry. Torque vs. field curves at low
temperatures demonstrate a ground state with S > 0 and exhibit a torque step
due to a field induced level-crossing at B* \approx 7.5 T, accompanied by an
abrupt change of magnetic anisotropy from easy-axis to hard-axis type. These
observations are discussed in terms of a spin Hamiltonian formalism.Comment: 4 pages, 4 figures, to be published in Phys. Rev. Let
Magnetic Excitations of the 2-D Sm Spin Layers in Sm(La,Sr)CuO4
We present specific heat and susceptibility data on Sm(La,Sr)CuO4 in magnetic
fields up to 9 T and temperatures down to 100 mK. We find a broad peak in
specific heat which is insensitive to magnetic field at a temperature of 1.5 K
with a value of 2.65 J/mol K. The magnetic susceptibility at 5 T continues to
increase down to 2 K, the lowest temperature measured. The data suggest that
the Sm spin system may be an ideal realization of the frustrated Heisenberg
antiferromagnet on the square lattice.Comment: 2 pages, 2 figures, submitted to IC
Duality Invariant M-theory: Gauged supergravities and Scherk-Schwarz reductions
We consider the reduction of the duality invariant approach to M-theory by a
U-duality group valued Scherk-Schwarz twist. The result is to produce
potentials for gauged supergravities that are normally associated with
non-geometric compactifications. The local symmetry reduces to gauge
transformations with the gaugings exactly matching those of the embedding
tensor approach to gauged supergravity. Importantly, this approach now includes
a nontrivial dependence of the fields on the extra coordinates of the extended
space.Comment: 22 pages Latex; v2: typos corrected and references adde
Improvement in accuracy of multiple sequence alignment using novel group-to-group sequence alignment algorithm with piecewise linear gap cost
BACKGROUND: Multiple sequence alignment (MSA) is a useful tool in bioinformatics. Although many MSA algorithms have been developed, there is still room for improvement in accuracy and speed. In the alignment of a family of protein sequences, global MSA algorithms perform better than local ones in many cases, while local ones perform better than global ones when some sequences have long insertions or deletions (indels) relative to others. Many recent leading MSA algorithms have incorporated pairwise alignment information obtained from a mixture of sources into their scoring system to improve accuracy of alignment containing long indels. RESULTS: We propose a novel group-to-group sequence alignment algorithm that uses a piecewise linear gap cost. We developed a program called PRIME, which employs our proposed algorithm to optimize the well-defined sum-of-pairs score. PRIME stands for Profile-based Randomized Iteration MEthod. We evaluated PRIME and some recent MSA programs using BAliBASE version 3.0 and PREFAB version 4.0 benchmarks. The results of benchmark tests showed that PRIME can construct accurate alignments comparable to the most accurate programs currently available, including L-INS-i of MAFFT, ProbCons, and T-Coffee. CONCLUSION: PRIME enables users to construct accurate alignments without having to employ pairwise alignment information. PRIME is available at
- …