4,170 research outputs found
Earth resources-regional transfer activity contracts review
A regional transfer activity contracts review held by the Earth Resources Office was summarized. Contracts in the earth resources field primarily directed toward applications of satellite data and technology in solution of state and regional problems were reviewed. A summary of the progress of each contract was given in order to share experiences of researchers across a seven state region. The region included Missouri, Kentucky, Tennessee, Mississippi, Alabama, Georgia, and North Carolina. Research in several earth science disciplines included forestry, limnology, water resources, land use, geology, and mathematical modeling. The use of computers for establishment of information retrieval systems was also emphasized
Preliminary Solar Sail Design and Fabrication Assessment: Spinning Sail Blade, Square Sail Sheet
Blade design aspects most affecting producibility and means of measurement and control of length, scallop, fullness and straightness requirements and tolerances were extensively considered. Alternate designs of the panel seams and edge reinforcing members are believed to offer advantages of seam integrity, producibility, reliability, cost and weight. Approaches to and requirements for highly specialized metalizing methods, processes and equipment were studied and identified. Alternate methods of sail blade fabrication and related special machinery, tooling, fixtures and trade offs were examined. A preferred and recommended approach is also described. Quality control plans, inspection procedures, flow charts and special test equipment associated with the preferred manufacturing method were analyzed and are discussed
Expansion algorithm for the density matrix
A purification algorithm for expanding the single-particle density matrix in
terms of the Hamiltonian operator is proposed. The scheme works with a
predefined occupation and requires less than half the number of matrix-matrix
multiplications compared to existing methods at low (90%)
occupancy. The expansion can be used with a fixed chemical potential in which
case it is an asymmetric generalization of and a substantial improvement over
grand canonical McWeeny purification. It is shown that the computational
complexity, measured as number of matrix multiplications, essentially is
independent of system size even for metallic materials with a vanishing band
gap.Comment: 5 pages, 4 figures, to appear in Phys. Rev.
Cloaked Facebook pages: Exploring fake Islamist propaganda in social media
This research analyses cloaked Facebook pages that are created to spread political propaganda by cloaking a user profile and imitating the identity of a political opponent in order to spark hateful and aggressive reactions. This inquiry is pursued through a multi-sited online ethnographic case study of Danish Facebook pages disguised as radical Islamist pages, which provoked racist and anti-Muslim reactions as well as negative sentiments towards refugees and immigrants in Denmark in general. Drawing on Jessie Daniels’ critical insights into cloaked websites, this research furthermore analyses the epistemological, methodological and conceptual challenges of online propaganda. It enhances our understanding of disinformation and propaganda in an increasingly interactive social media environment and contributes to a critical inquiry into social media and subversive politics
Size of Outbreaks Near the Epidemic Threshold
The spread of infectious diseases near the epidemic threshold is
investigated. Scaling laws for the size and the duration of outbreaks
originating from a single infected individual in a large susceptible population
are obtained. The maximal size of an outbreak n_* scales as N^{2/3} with N the
population size. This scaling law implies that the average outbreak size
scales as N^{1/3}. Moreover, the maximal and the average duration of an
outbreak grow as t_* ~ N^{1/3} and ~ ln N, respectively.Comment: 4 pages, 5 figure
Whirling Hexagons and Defect Chaos in Hexagonal Non-Boussinesq Convection
We study hexagon patterns in non-Boussinesq convection of a thin rotating
layer of water. For realistic parameters and boundary conditions we identify
various linear instabilities of the pattern. We focus on the dynamics arising
from an oscillatory side-band instability that leads to a spatially disordered
chaotic state characterized by oscillating (whirling) hexagons. Using
triangulation we obtain the distribution functions for the number of pentagonal
and heptagonal convection cells. In contrast to the results found for defect
chaos in the complex Ginzburg-Landau equation and in inclined-layer convection,
the distribution functions can show deviations from a squared Poisson
distribution that suggest non-trivial correlations between the defects.Comment: 4 mpg-movies are available at
http://www.esam.northwestern.edu/~riecke/lit/lit.html submitted to New J.
Physic
Scharnhorst effect at oblique incidence
We consider the Scharnhorst effect (anomalous photon propagation in the
Casimir vacuum) at oblique incidence, calculating both photon speed and
polarization states as functions of angle. The analysis is performed in the
framework of nonlinear electrodynamics and we show that many features of the
situation can be extracted solely on the basis of symmetry considerations.
Although birefringence is common in nonlinear electrodynamics it is not
universal; in particular we verify that the Casimir vacuum is not birefringent
at any incidence angle. On the other hand, group velocity is typically not
equal to phase velocity, though the distinction vanishes for special directions
or if one is only working to second order in the fine structure constant. We
obtain an ``effective metric'' that is subtly different from previous results.
The disagreement is due to the way that ``polarization sums'' are implemented
in the extant literature, and we demonstrate that a fully consistent
polarization sum must be implemented via a bootstrap procedure using the
effective metric one is attempting to define. Furthermore, in the case of
birefringence, we show that the polarization sum technique is intrinsically an
approximation.Comment: 11 pages double-column format, 2 figures, RevTeX 4.0 (beta 2). Final
versio
Requirement of a Membrane Potential for the Posttranslational Transfer of Proteins into Mitochondsria
Posttranslational transfer of most precursor proteins into mitochondria is dependent on energization of the mitochondria. Experiments were carried out to determine whether the membrane potential or the intramitochondrial ATP is the immediate energy source. Transfer in vitro of precursors to the ADP/ATP carrier and to ATPase subunit 9 into isolated Neurospora mitochondria was investigated. Under conditions where the level of intramitochondrial ATP was high and the membrane potential was dissipated, import and processing of these precursor proteins did not take place. On the other hand, precursors were taken up and processed when the intramitochondrial ATP level was low, but the membrane potential was not dissipated. We conclude that a membrane potential is involved in the import of those mitochondrial precursor proteins which require energy for intracellular translocatio
Stochastic pump effect and geometric phases in dissipative and stochastic systems
The success of Berry phases in quantum mechanics stimulated the study of
similar phenomena in other areas of physics, including the theory of living
cell locomotion and motion of patterns in nonlinear media. More recently,
geometric phases have been applied to systems operating in a strongly
stochastic environment, such as molecular motors. We discuss such geometric
effects in purely classical dissipative stochastic systems and their role in
the theory of the stochastic pump effect (SPE).Comment: Review. 35 pages. J. Phys. A: Math, Theor. (in press
Addressing Inequity to Achieve the Maternal and Child Health Millennium Development Goals: Looking Beyond Averages.
Inequity in access to and use of child and maternal health interventions is impeding progress towards the maternal and child health Millennium Development Goals. This study explores the potential health gains and equity impact if a set of priority interventions for mothers and under fives were scaled up to reach national universal coverage targets for MDGs in Tanzania. We used the Lives Saved Tool (LiST) to estimate potential reductions in maternal and child mortality and the number of lives saved across wealth quintiles and between rural and urban settings. High impact maternal and child health interventions were modelled for a five-year scale up, by linking intervention coverage, effectiveness and cause of mortality using data from Tanzania. Concentration curves were drawn and the concentration index estimated to measure the equity impact of the scale up. In the poorest population quintiles in Tanzania, the lives of more than twice as many mothers and under-fives were likely to be saved, compared to the richest quintile. Scaling up coverage to equal levels across quintiles would reduce inequality in maternal and child mortality from a pro rich concentration index of -0.11 (maternal) and -0.12 (children) to a more equitable concentration index of -0,03 and -0.03 respectively. In rural areas, there would likely be an eight times greater reduction in maternal deaths than in urban areas and a five times greater reduction in child deaths than in urban areas. Scaling up priority maternal and child health interventions to equal levels would potentially save far more lives in the poorest populations, and would accelerate equitable progress towards maternal and child health MDGs
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