178 research outputs found
UV excess galaxies: Wolf-Rayet galaxies
We discuss V and R band photometry for 67% of the Sullivan et al. 2000 SA57
ultraviolet-selected galaxy sample. In a sample of 176 UV-selected galaxies,
Sullivan et al. 2000 find that 24% have (UV-B) colors too blue for consistency
with starburst spectral synthesis models. We propose that these extreme blue,
UV excess galaxies are Wolf-Rayet (WR) galaxies, starburst galaxies with strong
UV emission from WR stars. We measure a median (V-R)=0.38+-0.06 for the
UV-selected sample, bluer than a sample optically selected at R but consistent
with starburst and WR galaxy colors. We demonstrate that redshifted WR emission
lines can double or triple the flux through the UV bandpass at high redshifts.
Thus the (UV-B) color of a WR galaxy can be up to 1.3 mag bluer at high
redshift, and the expected selection function is skewed to larger redshifts.
The redshift distribution of the extreme blue, UV excess galaxies matches the
selection function we predict from the properties of WR galaxies.Comment: 4 pages, including 4 figures. Uses AASTeX and emulateapj5.sty.
Includes referee change
Virtual target screening to rapidly identify potential protein targets of natural products in drug discovery
Inherent biological viability and diversity of natural products make them a potentially rich source for new therapeutics. However, identification of bioactive compounds with desired therapeutic effects and identification of their protein targets is a laborious, expensive process. Extracts from organism samples may show desired activity in phenotypic assays but specific bioactive compounds must be isolated through further separation methods and protein targets must be identified by more specific phenotypic and in vitro experimental assays. Still, questions remain as to whether all relevant protein targets for a compound have been identified. The desire is to understand breadth of purposing for the compound to maximize its use and intellectual property, and to avoid further development of compounds with insurmountable adverse effects. Previously we developed a Virtual Target Screening system that computationally screens one or more compounds against a collection of virtual protein structures. By scoring each compound-protein interaction, we can compare against averaged scores of synthetic drug-like compounds to determine if a particular protein would be a potential target of a compound of interest. Here we provide examples of natural products screened through our system as we assess advantages and shortcomings of our current system in regards to natural product drug discovery
Transiting Disintegrating Planetary Debris around WD 1145+017
More than a decade after astronomers realized that disrupted planetary
material likely pollutes the surfaces of many white dwarf stars, the discovery
of transiting debris orbiting the white dwarf WD 1145+017 has opened the door
to new explorations of this process. We describe the observational evidence for
transiting planetary material and the current theoretical understanding (and in
some cases lack thereof) of the phenomenon.Comment: Invited review chapter. Accepted March 23, 2017 and published October
7, 2017 in the Handbook of Exoplanets. 15 pages, 10 figure
Functionally distinct T-helper cell phenotypes predict resistance to different types of parasites in a wild mammal
The adaptive immune system is critical to an effective response to infection in vertebrates, with T-helper (Th) cells pivotal in orchestrating these responses. In natural populations where co-infections are the norm, different Th responses are likely to play an important role in maintaining host health and fitness, a relationship which remains poorly understood in wild animals. In this study, we characterised variation in functionally distinct Th responses in a wild population of Soay sheep by enumerating cells expressing Th-subset specific transcription factors and quantifying Th-associated cytokines. We tested the prediction that raised Th1 and Th2 responses should predict reduced apicomplexan and helminth parasite burdens, respectively. All measures of Th-associated cytokine production increased with age, while Th17- and regulatory Th-associated cytokine production increased more rapidly with age in males than females. Independent of age, sex, and each other, IL-4 and Gata3 negatively predicted gastro-intestinal nematode faecal egg count, while IFN-Îł negatively predicted coccidian faecal oocyst count. Our results provide important support from outside the laboratory that Th1 and Th2 responses predict resistance to different kinds of parasites, and illustrate how harnessing specific reagents and tools from laboratory immunology will illuminate our understanding of host-parasite interactions in the wild
Testing the companion hypothesis for the origin of the X-ray emission from intermediate-mass main-sequence stars
There is no straightforward explanation for intrinsic X-ray emission from
intermediate-mass main-sequence stars. Therefore the observed emission is often
interpreted in terms of (hypothesized) late-type magnetically active companion
stars. We use Chandra imaging observations to spatially resolve in X-rays a
sample of main-sequence B-type stars with recently discovered companions at
arcsecond separation. We find that all spatially resolved companions are X-ray
emitters, but seven out of eleven intermediate-mass stars are also X-ray
sources. If this emission is interpreted in terms of additional sub-arcsecond
or spectroscopic companions, this implies a high multiplicity of B-type stars.
Firm results on B star multiplicity pending, the alternative, that B stars
produce intrinsic X-rays, can not be discarded. The appropriate scenario in
this vein is might be a magnetically confined wind, as suggested for the X-ray
emission of the magnetic Ap star IQ Aur. However, the only Ap star in the
Chandra sample is not detected in X-rays, and therefore does not support this
picture.Comment: 12 pages; accepted for publication in Astronomy & Astrophysic
Illumination in symbiotic binary stars: Non-LTE photoionization models. II. Wind case
We describe a non-LTE photoionization code to calculate the wind structure
and emergent spectrum of a red giant wind illuminated by the hot component of a
symbiotic binary system. We consider spherically symmetric winds with several
different velocity and temperature laws and derive predicted line fluxes as a
function of the red giant mass loss rate, \mdot. Our models generally match
observations of the symbiotic stars EG And and AG Peg for \mdot about 10^{-8}
\msunyr to 10^{-7} \msunyr. The optically thick cross- section of the red giant
wind as viewed from the hot component is a crucial parameter in these models.
Winds with cross-sections of 2--3 red giant radii reproduce the observed
fluxes, because the wind density is then high, about 10^9 cm^{-3}. Our models
favor winds with acceleration regions that either lie far from the red giant
photosphere or extend for 2--3 red giant radii.Comment: 51 pages, LaTeX including three tables, requires 15 Encapsulated
Postscript figures, to appear in Ap
Proceedings of the I ndoâ U.S. bilateral workshop on accelerating botanicals/biologics agent development research for cancer chemoprevention, treatment, and survival
With the evolving evidence of the promise of botanicals/biologics for cancer chemoprevention and treatment, an IndoâU.S. collaborative Workshop focusing on âAccelerating Botanicals Agent Development Research for Cancer Chemoprevention and Treatmentâ was conducted at the Moffitt Cancer Center, 29â31 May 2012. Funded by the IndoâU.S. Science and Technology Forum, a joint initiative of Governments of India and the United States of America and the Moffitt Cancer Center, the overall goals of this workshop were to enhance the knowledge (agents, molecular targets, biomarkers, approaches, target populations, regulatory standards, priorities, resources) of a multinational, multidisciplinary team of researcher's to systematically accelerate the design, to conduct a successful clinical trials to evaluate botanicals/biologics for cancer chemoprevention and treatment, and to achieve efficient translation of these discoveries into the standards for clinical practice that will ultimately impact cancer morbidity and mortality. Expert panelists were drawn from a diverse group of stakeholders, representing the leadership from the National Cancer Institute's Office of Cancer Complementary and Alternative Medicine (OCCAM), NCI Experimental Therapeutics (NExT), Food and Drug Administration, national scientific leadership from India, and a distinguished group of population, basic and clinical scientists from the two countries, including leaders in bioinformatics, social sciences, and biostatisticians. At the end of the workshop, we established four IndoâU.S. working research collaborative teams focused on identifying and prioritizing agents targeting four cancers that are of priority to both countries. Presented are some of the key proceedings and future goals discussed in the proceedings of this workshop. With the evolving evidence of the promise of botanicals/biologics for cancer chemoprevention and treatment, the proceedings of the IndoâU.S. collaborative Workshop represent one of the most contemporary issues in Cancer Medicine .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/96353/1/cam442.pd
Proceedings of the I ndoâ U.S. bilateral workshop on accelerating botanicals/biologics agent development research for cancer chemoprevention, treatment, and survival
With the evolving evidence of the promise of botanicals/biologics for cancer chemoprevention and treatment, an IndoâU.S. collaborative Workshop focusing on âAccelerating Botanicals Agent Development Research for Cancer Chemoprevention and Treatmentâ was conducted at the Moffitt Cancer Center, 29â31 May 2012. Funded by the IndoâU.S. Science and Technology Forum, a joint initiative of Governments of India and the United States of America and the Moffitt Cancer Center, the overall goals of this workshop were to enhance the knowledge (agents, molecular targets, biomarkers, approaches, target populations, regulatory standards, priorities, resources) of a multinational, multidisciplinary team of researcher's to systematically accelerate the design, to conduct a successful clinical trials to evaluate botanicals/biologics for cancer chemoprevention and treatment, and to achieve efficient translation of these discoveries into the standards for clinical practice that will ultimately impact cancer morbidity and mortality. Expert panelists were drawn from a diverse group of stakeholders, representing the leadership from the National Cancer Institute's Office of Cancer Complementary and Alternative Medicine (OCCAM), NCI Experimental Therapeutics (NExT), Food and Drug Administration, national scientific leadership from India, and a distinguished group of population, basic and clinical scientists from the two countries, including leaders in bioinformatics, social sciences, and biostatisticians. At the end of the workshop, we established four IndoâU.S. working research collaborative teams focused on identifying and prioritizing agents targeting four cancers that are of priority to both countries. Presented are some of the key proceedings and future goals discussed in the proceedings of this workshop. With the evolving evidence of the promise of botanicals/biologics for cancer chemoprevention and treatment, the proceedings of the IndoâU.S. collaborative Workshop represent one of the most contemporary issues in Cancer Medicine .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/96353/1/cam442.pd
SKYSURF-4: Panchromatic HST All-Sky Surface-Brightness Measurement Methods and Results
The diffuse, unresolved sky provides most of the photons that the Hubble
Space Telescope (HST) receives, yet remains poorly understood. HST Archival
Legacy program SKYSURF aims to measure the 0.2-1.6 m sky surface
brightness (sky-SB) from over 140,000 HST images. We describe a sky-SB
measurement algorithm designed for SKYSURF that is able to recover the input
sky-SB from simulated images to within 1% uncertainty. We present our sky-SB
measurements estimated using this algorithm on the entire SKYSURF database.
Comparing our sky-SB spectral energy distribution (SED) to measurements from
the literature shows general agreements. Our SKYSURF SED also reveals a
possible dependence on Sun angle, indicating either non-isotropic scattering of
solar photons off interplanetary dust or an additional component to Zodiacal
Light. Finally, we update Diffuse Light limits in the near-IR based on the
methods from Carleton et al. (2022), with values of 0.009 MJy sr (22 nW
m sr) at 1.25 m, 0.015 MJy sr (32 nW m
sr) at 1.4 m, and 0.013 MJy sr (25 nW m sr) at
1.6 m. These estimates provide the most stringent all-sky constraints to
date in this wavelength range. SKYSURF sky-SB measurements are made public on
the official SKYSURF website and will be used to constrain Diffuse Light in
future papers.Comment: Revised based on helpful comments from the reviewer, and accepted to
AJ on April 12th, 2023. Main paper: 18 pages, 9 figures, 4 tables.
Appendices: 16 pages, 10 figures, 1 table. Main results shown in Figure 7 and
Table
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