6,235 research outputs found
Strongly coupled plasma with electric and magnetic charges
A number of theoretical and lattice results lead us to believe that
Quark-Gluon Plasma not too far from contains not only electrically
charged quasiparticles -- quarks and gluons -- but magnetically charged ones --
monopoles and dyons -- as well. Although binary systems like charge-monopole
and charge-dyon were considered in details before in both classical and quantum
settings, it is the first study of coexisting electric and magnetic particles
in many-body context. We perform Molecular Dynamics study of strongly coupled
plasmas with particles and different fraction of magnetic charges.
Correlation functions and Kubo formulae lead to such transport properties as
diffusion constant, shear viscosity and electric conductivity: we compare the
first two with empirical data from RHIC experiments as well as results from
AdS/CFT correspondence. We also study a number of collective excitations in
these systems.Comment: 2nd version, 22 pages, 32 figures: two important new figures have
been included to compare our results with RHIC experiments and AdS/CFT
results; a few new references and comments are added as wel
Long-range sound-mediated dark soliton interactions in trapped atomic condensates
A long-range soliton interaction is discussed whereby two or more dark
solitons interact in an inhomogeneous atomic condensate, modifying their
respective dynamics via the exchange of sound waves without ever coming into
direct contact. An idealized double well geometry is shown to yield perfect
energy transfer and complete periodic identity reversal of the two solitons.
Two experimentally relevant geometries are analyzed which should enable the
observation of this long-range interaction
Mobile phone and tablet apps to support young people’s management of their physical long-term conditions: a systematic review protocol
Background: The prevalence of long-term or chronic conditions that limit activity and reduce quality of life in young people aged 10-24 years is rising. This group has distinct health care needs and requires tailored support strategies to facilitate increasing personal responsibility for the management of their condition wherever possible, as they mature. Mobile phone and tablet mobile technologies featuring software program apps are already well used by young people for social networking or gaming. They have also been utilized in health care to support personal condition management, using condition-specific and patient-tailored software. Such apps have much potential, and there is an emerging body of literature on their use in a health context making this review timely. Objective: The objective of this paper is to develop a systematic review protocol focused on identifying and assessing the effectiveness of mobile phone and tablet apps that support young people’s management of their chronic conditions. Methods: The search strategy will include a combination of standardized indexed search terms and free-text terms related to the key concepts of young people; long-term conditions and mobile technology. Peer-reviewed journal articles published from 2003 that meet the inclusion and exclusion criteria will be identified through searching the generated hits from 5 bibliographical databases. Two independent reviewers will screen the titles and abstracts to determine which articles focus on testing interventions identified as a mobile phone or tablet apps, and that have been designed and delivered to support the management of long-term conditions in young people aged 10-24 years. Data extraction and quality assessment tools will be used to facilitate consistent analysis and synthesis. It is anticipated that several studies will meet the selection criteria but that these are likely to be heterogeneous in terms of study design, reported outcomes, follow-up times, participants’ age, and health condition. Sub-group analyses will be undertaken and where possible meta-analyses will take place.Results: This review will synthesize available knowledge surrounding tablet and mobile phone apps that support management of long term physical health conditions in young people. The findings will be synthesized to determine which elements of the technologies were most effective for this population. Conclusions: This systematic review aims to synthesize existing literature in order to generate findings that will facilitate the development of an app intervention. The review will form the first phase of development and evaluation of a complex intervention as recommended by the United Kingdom Medical Research Council. The knowledge gained from the review will be verified in subsequent phases, which will include primary qualitative work with health professionals and young people with long term conditions as research participants. Young people living with long-term conditions will be involved as co-researchers and consumer advisors in all subsequent phases to develop and evaluate an app to support the management of long-term physical health conditions
Aircraft remote sensing of soil moisture and hydrologic parameters, Taylor Creek, Florida, and Little River, Georgia, 1979 data report
Experiments were conducted to evaluate aircraft remote sensing techniques for hydrology in a wide range of physiographic and climatic regions using several sensor platforms. The data were collected in late 1978 and during 1979 in two humid areas--Taylor Creek, Fla., and Little River, Ga. Soil moisture measurements and climatic observations are presented as well as the remote sensing data collected using thermal infrared, passive microwave, and active microwave systems
Assessing a Hydrodynamic Description for Instabilities in Highly Dissipative, Freely Cooling Granular Gases
An intriguing phenomenon displayed by granular flows and predicted by
kinetic-theory-based models is the instability known as particle "clustering,"
which refers to the tendency of dissipative grains to form transient, loose
regions of relatively high concentration. In this work, we assess a
modified-Sonine approximation recently proposed [Garz\'o et al., Physica A 376,
94 (2007)] for a granular gas via an examination of system stability. In
particular, we determine the critical length scale associated with the onset of
two types of instabilities -vortices and clusters- via stability analyses of
the Navier-Stokes-order hydrodynamic equations by using the expressions of the
transport coefficients obtained from both the standard and the modified-Sonine
approximations. We examine the impact of both Sonine approximations over a
range of solids fraction \phi <0.2 for small restitution coefficients
e=0.25--0.4, where the standard and modified theories exhibit discrepancies.
The theoretical predictions for the critical length scales are compared to
molecular dynamics (MD) simulations, of which a small percentage were not
considered due to inelastic collapse. Results show excellent quantitative
agreement between MD and the modified-Sonine theory, while the standard theory
loses accuracy for this highly dissipative parameter space. The modified theory
also remedies a (highdissipation) qualitative mismatch between the standard
theory and MD for the instability that forms more readily. Furthermore, the
evolution of cluster size is briefly examined via MD, indicating that
domain-size clusters may remain stable or halve in size, depending on system
parameters.Comment: 4 figures; to be published in Phys. Rev.
Polyelectrolyte stars in planar confinement
We employ monomer-resolved Molecular Dynamics simulations and theoretical
considerations to analyze the conformations of multiarm polyelectrolyte stars
close to planar, uncharged walls. We identify three mechanisms that contribute
to the emergence of a repulsive star-wall force, namely: the confinement of the
counterions that are trapped in the star interior, the increase in
electrostatic energy due to confinement as well as a novel mechanism arising
from the compression of the stiff polyelectrolyte rods approaching the wall.
The latter is not present in the case of interaction between two
polyelectrolyte stars and is a direct consequence of the impenetrable character
of the planar wall.Comment: 34 pages, 8 figures. Revised version of the manuscript. To appear in
J. Chem. Phys. May, 200
Matter-wave bistability in coupled atom-molecule quantum gases
We study the matter-wave bistability in coupled atom-molecule quantum gases,
in which heteronuclear molecules are created via an interspecies Feshbach
resonance involving either two-species Bose or two-species Fermi atoms at zero
temperature. We show that the resonant two-channel Bose model is equivalent to
the nondegenerate parametric down-conversion in quantum optics, while the
corresponding Fermi model can be mapped to a quantum optics model that
describes a single-mode laser field interacting with an ensemble of
inhomogeneously broadened two-level atoms. Using these analogy and the fact
that both models are subject to the Kerr nonlinearity due to the two-body
s-wave collisions, we show that under proper conditions, the population in the
molecular state in both models can be made to change with the Feshbach detuning
in a bistable fashion.Comment: 6 pages, 5 figure
Octahedral Tilt Instability of ReO_3-type Crystals
The octahedron tilt transitions of ABX_3 perovskite-structure materials lead
to an anti-polar (or antiferroelectric) arrangement of dipoles, with the low
temperature structure having six sublattices polarized along various
crystallographic directions. It is shown that an important mechanism driving
the transition is long range dipole-dipole forces acting on both displacive and
induced parts of the anion dipole. This acts in concert with short range
repulsion, allowing a gain of electrostatic (Madelung) energy, both
dipole-dipole and charge-charge, because the unit cell shrinks when the hard
ionic spheres of the rigid octahedron tilt out of linear alignment.Comment: 4 page with 3 figures included; new version updates references and
clarifies the argument
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Mined Lands Inventory, Industrial Minerals, East Texas
The Bureau of Economic Geology, under an interagency cooperative contract with the Railroad Commission of Texas, conducted a comprehensive inventory of abandoned and active mining operations across 84 counties in East Texas. This report represents the second phase of the inventory, begun in 1988 in South Texas (Jackson and others, 1989). Project objectives were to characterize potential reclamation, or priority, sites, to create a surface-mining database of industrial minerals, and to provide data to meet future legislative and regulatory needs.
Comprehensive procedures were established for identification and evaluation of mined lands using U.S. Geological Survey topographic maps, black-and-white and color-infrared aerial photographs, on-site surveys, and low-altitude flyovers. The site location, mineral commodity, and relative size were recorded on a Mined Lands Inventory Form (MLIF) for each site greater than 2 acres. Data on health, safety, and environmental aspects were recorded for all priority sites. All data were entered into the Texas Mined Lands Database (TMLDB), a computer database that follows the format of the MLIF. Locations of all inventoried sites are shown on over 600 topographic maps.
In East Texas, 6,492 mined sites were identified, 3,341 greater than 2 acres, 3,112 less than 2 acres, and 39 of undetermined size. Among sites larger than 2 acres, approximately 1,637 are abandoned, 1,166 are active, and 573 are reclaimed. An estimated 140,000 acres have been disturbed by surface mining, predominantly by sand and gravel mining. Other commodities mined in the East Texas area include limestone, clay, and iron ore.Bureau of Economic Geolog
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