1,295 research outputs found
Examining the Genomic Influence of Skin Antioxidants In Vitro
A series of well-known, purified antioxidants including: Resveratrol, Epigallocatechin Gallate (EGCG), Genistein, Rosavin, Puerarin, Chlorogenic Acid, Propolis and two newer unexplored isoflavonoids isolated from Maclura pomifera (Osage Orange) including Pomiferin and Osajin, were applied to Normal Human Dermal Fibroblasts (NHDF) and Normal Human Dermal Keratinocytes (NHEK) for 24 hours. The resulting treated cells were then examined using human gene microarrays supplied by Agilent. These chips typically have somewhere on the order of 30,000 individual genes which are expressed in the human genome. For our study, this large list of genes was reduced to 205 principal genes thought to be important for skin and each individual ingredient was examined for its influence on the culled list of genes. Working on a hypothesis that there may be some common genes which are either upregulated or downregulated by all or most of these ingredients, a short list of genes for each cell line was developed. What appears to emerge from these studies is that several genes in the gene pool that was screened are influenced by most or all of the molecules of interest. Genes that appear to be upregulated in both cell lines by all the ingredients include: ACLY, AQP3, COX1, NOS3, and PLOD3. Genes that appear to be downregulated in both cell lines by all ingredients include only PGR
Global Existence and Regularity for the 3D Stochastic Primitive Equations of the Ocean and Atmosphere with Multiplicative White Noise
The Primitive Equations are a basic model in the study of large scale Oceanic
and Atmospheric dynamics. These systems form the analytical core of the most
advanced General Circulation Models. For this reason and due to their
challenging nonlinear and anisotropic structure the Primitive Equations have
recently received considerable attention from the mathematical community.
In view of the complex multi-scale nature of the earth's climate system, many
uncertainties appear that should be accounted for in the basic dynamical models
of atmospheric and oceanic processes. In the climate community stochastic
methods have come into extensive use in this connection. For this reason there
has appeared a need to further develop the foundations of nonlinear stochastic
partial differential equations in connection with the Primitive Equations and
more generally.
In this work we study a stochastic version of the Primitive Equations. We
establish the global existence of strong, pathwise solutions for these
equations in dimension 3 for the case of a nonlinear multiplicative noise. The
proof makes use of anisotropic estimates, estimates on the
pressure and stopping time arguments.Comment: To appear in Nonlinearit
Strong field limit analysis of gravitational retro-lensing
We present a complete treatment in the strong field limit of gravitational
retro-lensing by a static spherically symmetric compact object having a photon
sphere. The results are compared with those corresponding to ordinary lensing
in similar strong field situations. As examples of application of the
formalism, a supermassive black hole at the galactic center and a stellar mass
black hole in the galactic halo are studied as retro-lenses, in both cases
using the Schwarzschild and Reissner-Nordstrom geometries.Comment: 11 pages, 1 figure; v2: minor changes. Accepted for publication in
Physical Review
Viscosity of andesite melts and its implication for magma mixing prior to Unzen 1991-1995 eruption
The viscosity of an iron-bearing melt with composition similar to Unzen andesite was
determined experimentally in the high (109-1010.5 Pa·s) and low (5-1000 Pa·s) viscosity range
using a parallel plate viscometer and the falling sphere method, respectively. Falling sphere
experiments were carried out in an internally heated argon pressure vessel and in a piston
cylinder apparatus at 1323 to 1573 K and 200 to 2000 MPa. Creep experiments were
performed in the temperature range of 747 - 845 K at 300 MPa. The water content of the melt
varies from nominally dry to 6.2 wt% H2O. The Fe2+/Fetot ratio was determined for each
sample in the quenched glass using a colorimetric method. Pressure has minor influence on
the viscosity compared with the effect of temperature, water content (main compositional
parameter controlling the viscosity) or with the Fe2+/Fetot ratio (especially important at low
water content of the melt). Based on our new viscosity data and literature data with measured
Fe2+/Fetot ratio we propose a new empirical equation to estimate the viscosity η (in Pa·s) of
andesitic melts as a function of temperature T (in K), water content w (in wt%) and Fe2+/Fetot
ratio. The derived relationship reproduces the experimental data (87 in total) in the viscosity
range from 100.5 to 1013 Pa·s with a 1σ standard deviation of 0.17 log units. However,
application of this calculation model is limited to Fe2+/Fetot>0.3 and to temperatures above Tg.
Moreover, in the high viscosity range the variation of viscosity with water content is
constrained only by few experimental data and needs verification by additional
measurements.
The viscosity data are used to interpret mixing processes in the Unzen magma chamber prior
to 1991-1995 eruption. We demonstrate that the viscosities of the rhyolite and andesite melts
from the two end-member magmas are nearly identical prior and during mixing, enabling
efficient magma mixing
The viscosity of shoshonitic melts (Vulcanello Peninsula, Aeolian Islands, Italy): insight on the magma ascent in dikes
The viscosity of shoshonitic melts from Vulcanello Peninsula (Vulcano Island, Italy) is
experimentally determined at temperatures between 733 K and 1673 K. The water content of the
melts varies from 0.03 to 4.75 wt% H2O. The micropenetration technique is employed at ambient
pressure in the high viscosity range (109-1012 Pa·s). Falling sphere(s) experiments are performed
at 500 and 2000 MPa in the low viscosity range (100.5-103 Pa·s). Results show a decrease of about
2 orders of magnitude in viscosity if ~ 3 wt% of water is added to the dry melt at 1300 K. At high
temperature the viscosity of Vulcanello melts is intermediate between that of andesitic and
basaltic melts. In contrast, at low temperatures (≤1050 K), the shoshonitic melt is characterized
by a lower viscosity with respect to the two previous melts. Based on our new data set, a
calculation model is proposed to predict the viscosity of the shoshonitic melts as a function of
temperature and water content. The viscosity data are used to constrain the ascent velocity of
shoshonitic magmas from Vulcanello within dikes. Using petrological data (temperature and
crystal content of the magma) and volcanological information (geometrical parameters of the
eruptive fissure and depth of magma storage), we estimate the time scale for the ascent of magma
from the main reservoir to the surface. Results show time scales in the order of hours to few days.
We conclude that the rapid ascent of poorly evolved melts from Moho depths should be taken
into account for the hazard assessment of Vulcano Island
Structured matrices, continued fractions, and root localization of polynomials
We give a detailed account of various connections between several classes of
objects: Hankel, Hurwitz, Toeplitz, Vandermonde and other structured matrices,
Stietjes and Jacobi-type continued fractions, Cauchy indices, moment problems,
total positivity, and root localization of univariate polynomials. Along with a
survey of many classical facts, we provide a number of new results.Comment: 79 pages; new material added to the Introductio
Disparities in Vulnerability to Severe Complications from COVID-19 in the United States
Preexisting health conditions increase vulnerability to severe complications from COVID-19. Among middle-aged and older Americans, vulnerability to severe COVID-19 complications based on preexisting conditions is 2-3 times greater for those with low versus high income. Vulnerability is about 40% higher for middle-aged and older adults with a high school degree or less than adults with a four-year college degree. In every age group, Blacks are more vulnerable than Whites, but Hispanics are at lower risk based on fewer preexisting health conditions
Why Did Belgium Pay Leopold’s Bonds?
The longitudinal-optical (LO)-phonon coupling is experimentally examined by the optical decay of various charged and neutral exciton species in single quantum dots, and the related Huang-Rhys parameters are extracted. A positive trion exhibits significantly weaker LO-phonon replicas in the photoluminescence spectrum than the neutral and negatively charged species. Model computations show that the strength of the replicas is determined by the Coulomb interactions between electrons and holes, which modify the localization of the envelope wave functions and the net charge distribution.Original Publication: Daniel Dufåker, Fredrik Karlsson, V Dimastrodonato, L O Mereni, Bo Sernelius, Per-Olof Holtz and E Pelucchi, Phonon replicas of charged and neutral exciton complexes in single quantum dots, 2010, PHYSICAL REVIEW B, (82), 20, 205421. http://dx.doi.org/10.1103/PhysRevB.82.205421 Copyright: American Physical Society http://www.aps.org/</p
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