3,641 research outputs found
Analysis of proposed air drying process
An air drying process has been analyzed which is intended to reduce the water vapor content of a stratospheric sample to below one part per million by weight, based upon the removal of the water as it passes through a phosphorous pentoxide absorber. The analysis indicates that the method is feasible. Dependence on ram pressure to maintain flow through the absorber appears questionable and consideration should be given to other means
Backpack VLBI terminal with subscentimeter capability
Backpack portable equipment was developed to measure vector baseline from approximately 1 km to 100 km in length with subcentimeter to few centimeter accuracy. The equipment design features as well as the instrumentation specifications are discussed. It is shown that the unit has the following advantages: it is simple in concept; it is reliable in unattended operation; and it is inexpensive (less than $15,000 per unit)
Generic morphologies of viscoelastic dewetting fronts
A simple model is put forward which accounts for the occurrence of certain
generic dewetting morphologies in thin liquid coatings. It demonstrates that by
taking into account the elastic properties of the coating, a morphological
phase diagram may be derived which describes the observed structures of
dewetting fronts. It is demonstrated that dewetting morphologies may also serve
to determine nanoscale rheological properties of liquids.Comment: 4 pages, 2 figure
Coriolis force in Geophysics: an elementary introduction and examples
We show how Geophysics may illustrate and thus improve classical Mechanics
lectures concerning the study of Coriolis force effects. We are then interested
in atmospheric as well as oceanic phenomena we are familiar with, and are for
that reason of pedagogical and practical interest. Our aim is to model them in
a very simple way to bring out the physical phenomena that are involved.Comment: Accepted for publication in European Journal of Physic
Polarised black holes in ABJM
We numerically construct asymptotically solutions to
Einstein-Maxwell-dilaton theory. These have a dipolar electrostatic potential
turned on at the conformal boundary . We find two
classes of geometries: soliton solutions that encode the full
backreaction of the electric field on the geometry without a horizon, and
neutral black holes that are "polarised" by the dipolar potential. For a
certain range of the electric field , we find two distinct
branches of the soliton that exist for the same value of .
For the black hole, we find either two or four branches depending on the value
of the electric field and horizon temperature. These branches meet at critical
values of the electric field and impose a maximum value of that
should be reflected in the dual field theory. For both the soliton and black
hole geometries, we study boundary data such as the stress tensor. For the
black hole, we also consider horizon observables such as the entropy. At finite
temperature, we consider the Gibbs free energy for both phases and determine
the phase transition between them. We find that the soliton dominates at
low temperature for an electric field up to the maximum value. Using the
gauge/gravity duality, we propose that these solutions are dual to deformed
ABJM theory and compute the corresponding weak coupling phase diagram
Bioglass and bioactive glasses and their impact on healthcare
Glass caused a revolution in healthcare when Bioglass was discovered by Larry Hench. It was the first material to bond with bone, rather than be encapsulated by fibrous tissue, launching the field of bioactive ceramics . Bioglass is also biodegradable. Almost 50 years on from its discovery that revolution continues. Bioactive glasses stimulate more bone regeneration than other bioactive ceramics , which is attributed to their dissolution products stimulating cells at the genetic level. This second discovery has changed the way clinicians, scientists and regulatory bodies think about medical devices and the concept of bioactivity. The original 45S5 Bioglass has only re cently found really widespread use in orthop a edics, having regenerated the bones of more than 1.5 million patients. Its full potential is still yet to be fulfilled. Th is article takes the reader from Hench’s Bioglass 45S5 to its clinical uses and products, before giving examples of non - surgical products that now use Bioglass, from consumer products , such as toothpaste, to cosmetics . Other glasses have also found important healthcare applications, such as borate based glasses that heal chronic wounds. The re volution looks set to continue as new healthcare applications are being found for bioactive glasses, contributing to extending the glass age
An evaluation of the Goddard Space Flight Center Library
The character and degree of coincidence between the current and future missions, programs, and projects of the Goddard Space Flight Center and the current and future collection, services, and facilities of its library were determined from structured interviews and discussions with various classes of facility personnel. In addition to the tabulation and interpretation of the data from the structured interview survey, five types of statistical analyses were performed to corroborate (or contradict) the survey results and to produce useful information not readily attainable through survey material. Conclusions reached regarding compatability between needs and holdings, services and buildings, library hours of operation, methods of early detection and anticipation of changing holdings requirements, and the impact of near future programs are presented along with a list of statistics needing collection, organization, and interpretation on a continuing or longitudinal basis
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Polarised black holes in AdS
© 2016 IOP Publishing Ltd. We consider solutions in Einstein-Maxwell theory with a negative cosmological constant that asymptote to global AdS 4 with conformal boundary . At the sphere at infinity we turn on a space-dependent electrostatic potential, which does not destroy the asymptotic AdS behaviour. For simplicity we focus on the case of a dipolar electrostatic potential. We find two new geometries: (i) an AdS soliton that includes the full backreaction of the electric field on the AdS geometry; (ii) a polarised neutral black hole that is deformed by the electric field, accumulating opposite charges in each hemisphere. For both geometries we study boundary data such as the charge density and the stress tensor. For the black hole we also study the horizon charge density and area, and further verify a Smarr formula. Then we consider this system at finite temperature and compute the Gibbs free energy for both AdS soliton and black hole phases. The corresponding phase diagram generalizes the Hawking-Page phase transition. The AdS soliton dominates the low temperature phase and the black hole the high temperature phase, with a critical temperature that decreases as the external electric field increases. Finally, we consider the simple case of a free charged scalar field on with conformal coupling. For a field in the SU(N ) adjoint representation we compare the phase diagram with the above gravitational system
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