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 $\epsilon$-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 $\epsilon$-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 &amp; 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 &amp; ERA5), NSRDB PSM3, and CAMS Radiation Service (including McClear clear-sky irradiance).</p

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