1,180 research outputs found
Accounting estimates as cost inputs to logistics models
Production Function;econometrics
The use of heat and chemical penetration enhancers to increase the follicular delivery of erythromycin to the skin
Copyright © 2019. Published by Elsevier B.V.The effect of heat on the follicular absorption of drugs into the skin has not previously been investigated. In comparison to drug delivery across the continuous stratum corneum (SC), follicular absorption is known to be relatively rapid and therefore the use of short durations of heat may be particularly useful for enhancing drug delivery to the hair follicles, as well as being practical for patients to use. In this study erythromycin has been used as a model drug and the combined use of heat and chemical penetration enhancers was found to be able to synergistically increase the penetration of erythromycin into human skin via the follicular route. Moreover durations of heat application as short as 10 min in combination with particular enhancer systems were found to be sufficient to significantly increase erythromycin delivery to the skin. Overall the data indicate that the use of heat with chemical penetration enhancers offers a potentially valuable strategy for delivering drugs via the follicular route.Peer reviewedFinal Accepted Versio
Moduli-Space Dynamics of Noncommutative Abelian Sigma-Model Solitons
In the noncommutative (Moyal) plane, we relate exact U(1) sigma-model
solitons to generic scalar-field solitons for an infinitely stiff potential.
The static k-lump moduli space C^k/S_k features a natural K"ahler metric
induced from an embedding Grassmannian. The moduli-space dynamics is blind
against adding a WZW-like term to the sigma-model action and thus also applies
to the integrable U(1) Ward model. For the latter's two-soliton motion we
compare the exact field configurations with their supposed moduli-space
approximations. Surprisingly, the two do not match, which questions the
adiabatic method for noncommutative solitons.Comment: 1+15 pages, 2 figures; v2: reference added, to appear in JHE
Cosmological constraints on unparticle dark matter
In unparticle dark matter (unmatter) models the equation of state of the
unmatter is given by , where is the scaling factor.
Unmatter with such equations of state would have a significant impact on the
expansion history of the universe. Using type Ia supernovae (SNIa), the baryon
acoustic oscillation (BAO) measurements and the shift parameter of the cosmic
microwave background (CMB) to place constraints on such unmatter models we find
that if only the SNIa data is used the constraints are weak. However, with the
BAO and CMB shift parameter data added strong constraints can be obtained. For
the UDM model, in which unmatter is the sole dark matter, we find that
at 95% C.L. For comparison, in most unparticle physics models it is
assumed . For the CUDM model, in which unmatter co-exists with
cold dark matter, we found that the unmatter can at most make up a few percent
of the total cosmic density if , thus it can not be the major component
of dark matter.Comment: Replaced with revised version. BAO data is added to make a tighter
constraint. Version accepted for publication on Euro.Phys.J.
Off-Diagonal Hyperfine Interaction and Parity Non-conservation in Cesium
We have performed relativistic many-body calculations of the hyperfine
interaction in the and states of Cs, including the off-diagonal
matrix element. The calculations were used to determine the accuracy of the
semi-empirical formula for the electromagnetic transition amplitude
induced by the hyperfine interaction. We have found that even
though the contribution of the many-body effects into the matrix elements is
very large, the square root formula remains valid to the accuracy of a fraction of .
The result for the M1-amplitude is used in the interpretation of the
parity-violation measurement in the transition in Cs which claims a
possible deviation from the Standard model.Comment: 13 pages, 4 figures, LaTeX, Submitted to Phys. Rev.
Parity nonconservation in heavy atoms: The radiative correction enhanced by the strong electric field of the nucleus
Parity nonconservation due to the nuclear weak charge is considered. We
demonstrate that the radiative corrections to this effect due to the vacuum
fluctuations of the characteristic size larger than the nuclear radius
and smaller than the electron Compton wave-length are enhanced
because of the strong electric field of the nucleus. The parameter that allows
one to classify the corrections is the large logarithm .
The vacuum polarization contribution is enhanced by the second power of the
logarithm. Although the self-energy and the vertex corrections do not vanish,
they contain only the first power of the logarithm. The value of the radiative
correction is 0.4% for Cs and 0.9% for Tl, Pb, and Bi. We discuss also how the
correction affects the interpretation of the experimental data on parity
nonconservation in atoms.Comment: 4 pages, 3 figures, RevTe
Parity Violating Measurements of Neutron Densities
Parity violating electron nucleus scattering is a clean and powerful tool for
measuring the spatial distributions of neutrons in nuclei with unprecedented
accuracy. Parity violation arises from the interference of electromagnetic and
weak neutral amplitudes, and the of the Standard Model couples primarily
to neutrons at low . The data can be interpreted with as much confidence
as electromagnetic scattering. After briefly reviewing the present theoretical
and experimental knowledge of neutron densities, we discuss possible parity
violation measurements, their theoretical interpretation, and applications. The
experiments are feasible at existing facilities. We show that theoretical
corrections are either small or well understood, which makes the interpretation
clean. The quantitative relationship to atomic parity nonconservation
observables is examined, and we show that the electron scattering asymmetries
can be directly applied to atomic PNC because the observables have
approximately the same dependence on nuclear shape.Comment: 38 pages, 7 ps figures, very minor changes, submitted to Phys. Rev.
Precise calculation of parity nonconservation in cesium and test of the standard model
We have calculated the 6s-7s parity nonconserving (PNC) E1 transition
amplitude, E_{PNC}, in cesium. We have used an improved all-order technique in
the calculation of the correlations and have included all significant
contributions to E_{PNC}. Our final value E_{PNC} = 0.904 (1 +/- 0.5 %) \times
10^{-11}iea_{B}(-Q_{W}/N) has half the uncertainty claimed in old calculations
used for the interpretation of Cs PNC experiments. The resulting nuclear weak
charge Q_{W} for Cs deviates by about 2 standard deviations from the value
predicted by the standard model.Comment: 24 pages, 8 figure
The Weak Charge of the Proton and New Physics
We address the physics implications of a precision determination of the weak
charge of the proton, QWP, from a parity violating elastic electron proton
scattering experiment to be performed at the Jefferson Laboratory. We present
the Standard Model (SM) expression for QWP including one-loop radiative
corrections, and discuss in detail the theoretical uncertainties and missing
higher order QCD corrections. Owing to a fortuitous cancellation, the value of
QWP is suppressed in the SM, making it a unique place to look for physics
beyond the SM. Examples include extra neutral gauge bosons, supersymmetry, and
leptoquarks. We argue that a QWP measurement will provide an important
complement to both high energy collider experiments and other low energy
electroweak measurements. The anticipated experimental precision requires the
knowledge of the order alpha_s corrections to the pure electroweak box
contributions. We compute these contributions for QWP, as well as for the weak
charges of heavy elements as determined from atomic parity violation.Comment: 22 pages of LaTeX, 5 figure
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Sporormiella as a tool for detecting the presence of large herbivores in the Neotropics
The reliability of using the abundance of Sporormiella spores as a proxy for the presence and abundance of megaherbivores was tested in southern Brazil. Mud-water interface samples from nine lakes, in which cattle-use was categorized as high, medium, or low, were assayed for Sporormiella representation. The sampling design allowed an analysis of both the influence of the number of animals using the shoreline and the distance of the sampling site from the nearest shoreline. Sporormiella was found to be a reliable proxy for the presence of large livestock. The concentration and abundance of spores declined from the edge of the lake toward the center, with the strongest response being in sites with high livestock use. Consistent with prior studies in temperate regions, we find that Sporormiella spores are a useful proxy to study the extinction of Pleistocene megafauna or the arrival of European livestock in Neotropical landscapes
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