8,595 research outputs found
493— The Effects of 5-Azacytidine on HLA-ABC, HLA-E, HLA-G and HLA-A Expression
Epigenetic modifiers, like the DNA methylation inhibitor 5-Azacytidine (5-AzaC), have been shown to increase human leukocyte antigen (HLA) expression. The expression of HLA is required for a T-cell response to detect tumor cells. A lack of HLA expression allows tumor cells to escape immune detection. It has been previously shown that 5-AzaC is able to upregulate HLA-ABC expression in the cell line MDA-MB-435. However, other HLA proteins like HLA-E and HLA-G may be concurrently upregulated, which would have negative implications on tumor immunity. One flask of MDA-MB-435 cells was treated for 48 hours with 5-AzaC at 0.0025 mg/mL and another was left untreated. The cells were harvested and incubated with control antibodies or the experimental antibodies, Anti-HLA-ABC, Anti-HLA-G, and Anti-HLA-E and analyzed via flow cytometry. Preliminary experiments testing for the expression of HLA-E and HLA-G have both demonstrated a slight increase in their expression compared to the untreated cells. Although minor, the increase in HLA-E and HLA-G expression may have negative implications on tumor survival and pathogenesis. Understanding individual HLA upregulation may prove to be beneficial and applicable to cancer immunotherapy, an expanding field of improved cancer treatments
Pulsational Analysis of the Cores of Massive Stars and its Relevance to Pulsar Kicks
The mechanism responsible for the natal kicks of neutron stars continues to
be a challenging problem. Indeed, many mechanisms have been suggested, and one
hydrodynamic mechanism may require large initial asymmetries in the cores of
supernova progenitor stars. Goldreich, Lai, & Sahrling (1997) suggested that
unstable g-modes trapped in the iron (Fe) core by the convective burning layers
and excited by the -mechanism may provide the requisite asymmetries.
We perform a modal analysis of the last minutes before collapse of published
core structures and derive eigenfrequencies and eigenfunctions, including the
nonadiabatic effects of growth by nuclear burning and decay by both neutrino
and acoustic losses. In general, we find two types of g-modes: inner-core
g-modes, which are stabilized by neutrino losses and outer-core g-modes which
are trapped near the burning shells and can be unstable. Without exception, we
find at least one unstable g-mode for each progenitor in the entire mass range
we consider, 11 M_{\sun} to 40 M_{\sun}. More importantly, we find that the
timescales for growth and decay are an order of magnitude or more longer than
the time until the commencement of core collapse. We conclude that the
-mechanism may not have enough time to significantly amplify core
g-modes prior to collapse.Comment: 32 pages including 12 color figures and 2 tables, submitted to Ap
pvlib iotools—Open-source Python functions for seamless access to solar irradiance data
Access to accurate solar resource data is critical for numerous applications, including estimating the yield of solar energy systems, developing radiation models, and validating irradiance datasets. However, lack of standardization in data formats and access interfaces across providers constitutes a major barrier to entry for new users. pvlib python's iotools subpackage aims to solve this issue by providing standardized Python functions for reading local files and retrieving data from external providers. All functions follow a uniform pattern and return convenient data outputs, allowing users to seamlessly switch between data providers and explore alternative datasets. The pvlib package is community-developed on GitHub: https://github.com/pvlib/pvlib-python. As of pvlib python version 0.9.5, the iotools subpackage supports 12 different datasets, including ground measurement, reanalysis, and satellite-derived irradiance data. The supported ground measurement networks include the Baseline Surface Radiation Network (BSRN), NREL MIDC, SRML, SOLRAD, SURFRAD, and the US Climate Reference Network (CRN). Additionally, satellite-derived and reanalysis irradiance data from the following sources are supported: PVGIS (SARAH & ERA5), NSRDB PSM3, and CAMS Radiation Service (including McClear clear-sky irradiance).</p
pvlib iotools—Open-source Python functions for seamless access to solar irradiance data
Access to accurate solar resource data is critical for numerous applications, including estimating the yield of solar energy systems, developing radiation models, and validating irradiance datasets. However, lack of standardization in data formats and access interfaces across providers constitutes a major barrier to entry for new users. pvlib python's iotools subpackage aims to solve this issue by providing standardized Python functions for reading local files and retrieving data from external providers. All functions follow a uniform pattern and return convenient data outputs, allowing users to seamlessly switch between data providers and explore alternative datasets. The pvlib package is community-developed on GitHub: https://github.com/pvlib/pvlib-python. As of pvlib python version 0.9.5, the iotools subpackage supports 12 different datasets, including ground measurement, reanalysis, and satellite-derived irradiance data. The supported ground measurement networks include the Baseline Surface Radiation Network (BSRN), NREL MIDC, SRML, SOLRAD, SURFRAD, and the US Climate Reference Network (CRN). Additionally, satellite-derived and reanalysis irradiance data from the following sources are supported: PVGIS (SARAH & ERA5), NSRDB PSM3, and CAMS Radiation Service (including McClear clear-sky irradiance).</p
18F-fluorothymidine (FLT)-PET and diffusion-weighted MRI for early response evaluation in patients with small cell lung cancer:a pilot study
ArborZ: Photometric Redshifts Using Boosted Decision Trees
Precision photometric redshifts will be essential for extracting cosmological
parameters from the next generation of wide-area imaging surveys. In this paper
we introduce a photometric redshift algorithm, ArborZ, based on the
machine-learning technique of Boosted Decision Trees. We study the algorithm
using galaxies from the Sloan Digital Sky Survey and from mock catalogs
intended to simulate both the SDSS and the upcoming Dark Energy Survey. We show
that it improves upon the performance of existing algorithms. Moreover, the
method naturally leads to the reconstruction of a full probability density
function (PDF) for the photometric redshift of each galaxy, not merely a single
"best estimate" and error, and also provides a photo-z quality figure-of-merit
for each galaxy that can be used to reject outliers. We show that the stacked
PDFs yield a more accurate reconstruction of the redshift distribution N(z). We
discuss limitations of the current algorithm and ideas for future work.Comment: 10 pages, 13 figures, submitted to Ap
Energy landscape - a key concept for the dynamics of glasses and liquids
There is a growing belief that the mode coupling theory is the proper
microscopic theory for the dynamics of the undercooled liquid above a critical
temperature T_c. In addition, there is some evidence that the system leaves the
saddlepoints of the energy landscape to settle in the valleys at this critical
temperature. Finally, there is a microscopic theory for the entropy at the
calorimetric glass transition T_g by Mezard and Parisi, which allows to
calculate the Kauzmann temperature from the atomic pair potentials.
The dynamics of the frozen glass phase is at present limited to
phenomenological models. In the spirit of the energy landscape concept, one
considers an ensemble of independent asymmetric double-well potentials with a
wide distribution of barrier heights and asymmetries (ADWP or Gilroy-Phillips
model). The model gives an excellent description of the relaxation of glasses
up to about T_g/4. Above this temperature, the interaction between different
relaxation centers begins to play a role. One can show that the interaction
reduces the number of relaxation centers needed to bring the shear modulus down
to zero by a factor of three.Comment: Contribution to the III Workshop on Nonequilibrium Phenomena in
Supercooled Fluids, Glasses and Amorphous Materials, 22-27 September 2002,
Pisa; 14 pages, 3 figures; Version 3 takes criticque at Pisa into account;
final version 4 will be published in J.Phys.: Condens.Matte
Mechanical Relaxation in Glasses and at the Glass Transition
The Gilroy-Phillips model of relaxational jumps in asymmetric double-well
potentials, developed for the Arrhenius-type secondary relaxations of the glass
phase, is extended to a formal description of the breakdown of the shear
modulus at the glass transition, the flow process.Comment: 13 pages, 11 figures, 49 ref
String-like Clusters and Cooperative Motion in a Model Glass-Forming Liquid
A large-scale molecular dynamics simulation is performed on a glass-forming
Lennard-Jones mixture to determine the nature of dynamical heterogeneities
which arise in this model fragile liquid. We observe that the most mobile
particles exhibit a cooperative motion in the form of string-like paths
(``strings'') whose mean length and radius of gyration increase as the liquid
is cooled. The length distribution of the strings is found to be similar to
that expected for the equilibrium polymerization of linear polymer chains.Comment: 6 pages of RevTex, 6 postscript figures, uses epsf.st
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