293 research outputs found
Casimir-Polder interaction of fullerene molecules with surfaces
We calculate the thermal Casimir--Polder potential of C60 and C70 fullerene
molecules near gold and silicon nitride surfaces, motivated by their relevance
for molecular matter wave interference experiments. We obtain the coefficients
governing the asymptotic power laws of the interaction in the thermal, retarded
and nonretarded distance regimes and evaluate the full potential numerically.
The interaction is found to be dominated by electronic transitions, and hence
independent of the internal temperature of the molecules. The contributions
from phonon transitions, which are affected by the molecular temperature, give
rise to only a small correction. Moreover, we find that the sizeable molecular
line widths of thermal fullerenes may modify the nonretarded interaction,
depending on the model used. Detailed measurements of the nonretarded potential
of fullerene thus allow one to distinguish between different theories of
incorporating damping.Comment: 9 pages, 8 figures, 9 table
Interatomic van der Waals potential in the presence of a magneto-electric sphere
On the basis of a general formula obtained earlier via fourth-order
erturbation theory within the framework of macroscopic quantum electrodynamics,
the van der Waals potential between two neutral, unpolarized, ground-state
atoms in the presence of a homogeneous, dispersing and absorbing
magnetoelectric sphere is studied. When the radius of the sphere becomes
sufficiently large, the result asymptotically agrees with that for two atoms
near a planar interface. In the opposite limit of a very small sphere, the
sphere can effectively be regarded as being a third ground-state atom, and the
nonadditive three-atom van der Waals potential is recovered. To illustrate the
effect of a sphere of arbitrary radius, numerical results are presented for the
triangular arrangement where the atoms are at equidistance from the sphere, and
for the linear arrangement where the atoms and the sphere are aligned along a
straight line. As demonstrated, the enhancement or reduction of the interaction
potential in the presence of purely electric or magnetic spheres can be
physically understood in terms of image charges.Comment: 13 pages, 7 figure
Estimated annual economic impacts from harmful algal blooms (HABs) in the United States
Blooms of toxic or harmful microalgae, commonly called "red tides," represent a significant and expanding threat to human
health and fisheries resources throughout the United States and the world. Ecological, aesthetic, and public health impacts
include: mass mortalities of wild and farmed fish and shellfish, human intoxication and death from the consumption of
contaminated shellfish or fish, alterations of marine food webs through adverse effects on larvae and other life history stages of
commercial fish species, the noxious smell and appearance of algae accumulated in nearshore waters or deposited on beaches, and
mass mortalities of marine mammals, seabirds, and other animals.
In this report, we provide an estimate of the economic impacts of HABs in the United States from events where such impacts
were measurable with a fair degree of confidence during the interval 1987-92. The total economic impact averaged $49 million
per year, with public health impacts representing the largest component (45 percent). Commercial fisheries impacts were the next
largest (37 percent of the total), while recreation/tourism accounted for 13 percent, and monitoring/management impacts 4 percent.
These estimates are highly conservative, as many economic costs or impacts from HABs could not be estimated.Funding was provided by the National Oceanic and Atmospheric
Administration under Grants No. NA46RG0470 and NA90AA-D-SG480, the
National Science Foundation under Grant No. OCE-9321244, and the Johnson
Endowment of the Marine Policy Center
Ground-state van der Waals forces in planar multilayer magnetodielectrics
Within the frame of lowest-order perturbation theory, the van der Waals
potential of a ground-state atom placed within an arbitrary dispersing and
absorbing magnetodielectric multilayer system is given. Examples of an atom
situated in front of a magnetodielectric plate or between two such plates are
studied in detail. Special emphasis is placed on the competing attractive and
repulsive force components associated with the electric and magnetic matter
properties, respectively, and conditions for the formation of repulsive
potential walls are given. Both numerical and analytical results are presented.Comment: 16 pages, 8 figures, minor correction
Surface-induced heating of cold polar molecules
We study the rotational and vibrational heating of diatomic molecules placed
near a surface at finite temperature on the basis of macroscopic quantum
electrodynamics. The internal molecular evolution is governed by transition
rates that depend on both temperature and position. Analytical and numerical
methods are used to investigate the heating of several relevant molecules near
various surfaces. We determine the critical distances at which the surface
itself becomes the dominant source of heating and we investigate the transition
between the long-range and short-range behaviour of the heating rates. A simple
formula is presented that can be used to estimate the surface-induced heating
rates of other molecules of interest. We also consider how the heating depends
on the thickness and composition of the surface.Comment: 17 pages, 7 figure
Distinguishing models of surface response through the self-energy of an electron
The self-energy of an electron confined between parallel surfaces with arbitrary dielectric properties is calculated. The mechanism for this effect is the surface-induced modification of the fluctuating quantized vacuum field to which the electron is coupled, thereby endowing it with a surface-dependent self-energy in broad analogy to the Casimir-Polder effect for an atom. We derive a general formula for this self-energy shift and find that its sign is different for two commonly used models of surface response, namely, the plasma model and the Drude model. We propose an experiment which could detect this difference in sign, shedding light on continuing uncertainty about the correct description of the interaction of low-frequency vacuum photons with media
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A combined biomarker and clinical panel for chronic graft versus host disease diagnosis.
Whilst many chronic graft versus host disease (cGVHD) biomarkers have been previously reported, few have been verified in an independent cGVHD cohort. We aimed to verify the diagnostic accuracy of previously reported markers of cGVHD in a multi-centre Chronic GVHD Consortium. A total of 42 RNA and 18 protein candidate biomarkers were assessed amongst 59 cGVHD cases and 33 matched non-GVHD controls. Total RNA was isolated from PBMC, and RNA markers were quantified using PCR. Serum protein markers were quantified using ELISA. A combined 3 RNA biomarker (IRS2, PLEKHF1 and IL1R2) and 2 clinical variables (recipient CMV serostatus and conditioning regimen intensity) panel accurately (AUC 0.81) segregated cGVHD cases from controls. Other studied RNA and protein markers were not confirmed as accurate cGVHD diagnostic biomarkers. The studied markers failed to segregate higher risk cGVHD (per overall NIH 0-3 score, and overlap versus classic cGVHD status). These data support the need for multiple independent verification studies for the ultimate clinical application of cGVHD diagnostic biomarkers
Penyusunan Zona Pemanfaatan Dan Konservasi Airtanah Pada Cekungan Airtanah (CAT) Wonosobo, Provinsi Jawa Tengah_Turnitin
Local-field correction to one- and two-atom van der Waals interactions
Based on macroscopic quantum electrodynamics in linearly and causally
responding media, we study the local-field corrected van der Waals potentials
and forces for unpolarized ground-state atoms placed within a magnetoelectric
medium of arbitrary size and shape. We start from general expressions for the
van der Waals potentials in terms of the (classical) Green tensor of the
electromagnetic field and the atomic polarizability and incorporate the
local-field correction by means of the real-cavity model. In this context,
special emphasis is given to the decomposition of the Green tensor into a
medium part multiplied by a global local-field correction factor and, in the
single-atom case, a part that only depends on the cavity characteristics. The
result is used to derive general formulas for the local-field corrected van der
Waals potentials and forces. As an application, we calculate the van der Waals
potential between two ground-state atoms placed within magnetoelectric bulk
material.Comment: 9 pages, 2 figures, corrections according to erratu
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