10,770 research outputs found
Using Biobrane: Techniques to Make Life Easier
Aims: To facilitate the use of Biobrane for those burn care practitioners not familiar with this material. Methods: Two techniques have been developed through extensive use of Biobrane over many years, in both sheet and glove form. These techniques have been described and illustrated with photographs. Results: The use of these techniques has allowed the corresponding author to markedly reduce operating time and to easily apply the material single-handedly. Conclusion: Biobrane is a biosynthetic skin substitute primarily designed for the definitive treatment of superficial partial-thickness to mid-dermal burn injury. Once experienced with its use, the material is quite ubiquitous. The described techniques will facilitate the use of Biobrane for those not familiar with it
Total scattering descriptions of local and cooperative distortions in the oxide spinel (Mg,Cu)Cr2O4 with dilute Jahn-Teller ions
The normal spinel oxide MgCr2O4 is cubic at room temperature while the normal
spinel CuCr2O4 is tetragonal as a consequence of the Jahn-Teller nature of Cu2+
on the tetrahedral sites. Despite different end-member structures, complete
solid solutions of Mg_{1-x}Cu_xCr2O4 can be prepared that display a first-order
structural transition with composition x = 0.43 at room temperature. Reverse
Monte Carlo analysis of total neutron scattering on data acquired between 300 K
and 15 K on samples with x = 0.10, 0.20, and 0.43 provides unbiased local and
average structure descriptions of the samples, including an understanding of
the transition from local Jahn-Teller distortions in the cubic phase to
cooperative distortions that result in a tetragonal structure. Distributions of
continuous symmetry measures help to understand and distinguish distorted and
undistorted coordination around the tetrahedral site in the solid solutions.
Magnetic exchange bias is observed in field-cooled hysteresis loops of samples
with dilute Cu2+ concentration and in samples with tetragonal--cubic phase
coexistence around 300 K.Comment: 10 pages, 14 figure
Pre-Hawking Radiation from a Collapsing Shell
We investigate the effect of induced massive radiation given off during the
time of collapse of a massive spherically symmetric domain wall in the context
of the functional Schr\"odinger formalism. Here we find that the introduction
of mass suppresses the occupation number in the infrared regime of the induced
radiation during the collapse. The suppression factor is found to be given by
, which is in agreement with the expected Planckian distribution
of induced radiation. Thus a massive collapsing domain wall will radiate mostly
(if not exclusively) massless scalar fields, making it difficult for the domain
wall to shed any global quantum numbers and evaporate before the horizon is
formed.Comment: 10 pages, 3 figures. We updated the acknowledgments as well as added
a statement clarifying that we are following the methods first laid out in
Phys. Rev. D 76, 024005 (2007
Irreversibility in response to forces acting on graphene sheets
The amount of rippling in graphene sheets is related to the interactions with
the substrate or with the suspending structure. Here, we report on an
irreversibility in the response to forces that act on suspended graphene
sheets. This may explain why one always observes a ripple structure on
suspended graphene. We show that a compression-relaxation mechanism produces
static ripples on graphene sheets and determine a peculiar temperature ,
such that for the free-energy of the rippled graphene is smaller than
that of roughened graphene. We also show that depends on the structural
parameters and increases with increasing sample size.Comment: 4 pages, 4 Figure
The measurement of the winds near the ocean surface with a radiometer-scatterometer on Skylab
The author has identified the following significant results. There were a total of twenty-six passes in the ZLV mode that yielded useful data. Six were in the in-track noncontiguous mode; all others were in the cross-track noncontiguous mode. The wind speed and direction, as effectively determined in a neutral atmosphere at 19.5 m above the sea surface, were found for each cell scanned by S193. It is shown how the passive microwave measurements were used both to compute the attenuation of the radar beam and to determine those cells where the backscatter measurement was suspect. Given the direction of the wind from some independent source, with the typical accuracy of measurement by available meteorological methods, a backscatter measurement at a nadir angle of 50, 43, or 32 deg can be used to compute the speed of the wind averaged over the illuminated area
Static Versus Dynamic Friction: The Role of Coherence
A simple model for solid friction is analyzed. It is based on tangential
springs representing interlocked asperities of the surfaces in contact. Each
spring is given a maximal strain according to a probability distribution. At
their maximal strain the springs break irreversibly. Initially all springs are
assumed to have zero strain, because at static contact local elastic stresses
are expected to relax. Relative tangential motion of the two solids leads to a
loss of coherence of the initial state: The springs get out of phase due to
differences in their sizes. This mechanism alone is shown to lead to a
difference between static and dynamic friction forces already. We find that in
this case the ratio of the static and dynamic coefficients decreases with
increasing relative width of the probability distribution, and has a lower
bound of 1 and an upper bound of 2.Comment: 10 pages, 2 figures, revtex
Definitions of community: an illustration of aggregation bias, Station Bulletin, no.516
The Bulletin is a publication of the New Hampshire Agricultural Experiment Station, College of Life Sciences and Agriculture, University of New Hampshire, Durham, New Hampshire
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