1,789 research outputs found
Growth of mercuric iodide (HgI2) for nuclear radiation detectors
Mercuric iodide is a material used for the fabrication of the sensing element in solid state X-ray and gamma ray detecting instruments. The operation of the devices is determined to a large degree by the density of structural defects in the single crystalline material used in the sensing element. Since there were strong indications that the quality of the material was degraded by the effects of gravity during the growth process, a research and engineering program was initiated to grow one or more crystals of mercuric iodide in the reduced gravity environment of space. A special furnace assembly was designed which could be accommodated in a Spacelab rack, and at the same time made it possible to use the same growth procedures and controls used when growing a crystal on the ground. The space crystal, after the flight, was subjected to the same evaluation methods used for earth-grown crystals, so that comparisons could be made
The age of 47Tuc from self-consistent isochrone fits to colour-magnitude diagrams and the eclipsing member V69
Our aim is to derive a self-consistent age, distance and composition for the
globular cluster Tucanae (Tuc; NGC104). First, we reevaluate the
reddening towards the cluster resulting in a nominal as
the best estimate. The of the components of the eclipsing binary
member V69 is found to be K from both photometric and spectroscopic
evidence. This yields a true distance modulus (random)(systematic) to Tuc when combined with existing measurements of
V69 radii and luminosity ratio. We then present a new completely
self-consistent isochrone fitting method to ground based and
cluster colour-magnitude diagrams and the eclipsing binary member V69. The
analysis suggests that the composition of V69, and by extension one of the
populations of Tuc, is given by [Fe/H], [O/Fe], and
on the solar abundance scale of Asplund, Grevesse & Sauval.
However, this depends on the accuracy of the model scale which is
50-75 K cooler than our best estimate but within measurement uncertainties. Our
best estimate of the age of Tuc is 11.8 Gyr, with firm () lower
and upper limits of 10.4 and 13.4 Gyr, respectively, in satisfactory agreement
with the age derived from the white dwarf cooling sequence if our determination
of the distance modulus is adopted.Comment: 19 pages, 8 figures, accepted for publication in MNRA
The effects of cultivar on nodulation, seed yield, and dinitrogen fixation of dry bean (Phaseolus vulgaris L.)
Non-Peer Reviewe
Breaking the Law: The Failure to Award Mandatory Criminal Restitution to Victims in Sex Trafficking Cases
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The Science of Spin: Targeted Strategies to Manufacture Doubt With Detrimental Effects on Environmental and Public Health
Background Numerous groups, such as the tobacco industry, have deliberately altered and misrepresented knowable facts and empirical evidence to promote an agenda, often for monetary benefit, with consequences for environmental and public health. Previous research has explored cases individually, but none have conducted an in-depth comparison between cases. The purpose of this study was to compile a comprehensive list of tactics used by disparate groups and provide a framework for identifying further instances of manufactured doubt. Methods We examined scholarly books, peer-reviewed articles, well-researched journalism pieces, and legal evidence related to five disparate industries and organizations selected for their destructive impacts on environmental and public health (tobacco, coal, and sugar industries, manufacturers of the pesticide Atrazine, and the Marshall Institute, an institute focused on climate change research, and other scientists from the era that associated with those in the Institute). These documents provided evidence for a list of tactics used to generate pro-industry spin and manufacture doubt about conferred harm. We then identified trends among sets of strategies that could explain their differential use or efficacy. Results We recognized 28 unique tactics used to manufacture doubt. Five of these tactics were used by all five organizations, suggesting that they are key features of manufactured doubt. The intended audience influences the strategy used to misinform, and logical fallacies contribute to their efficacy. Conclusions This list of tactics can be used by others to build a case that an industry or group is deliberately manipulating information associated with their actions or products. Improved scientific and rhetorical literacy could be used to render them less effective, depending on the audience targeted, and ultimately allow for the protection of both environmental health and public health more generally
Age and helium content of the open cluster NGC 6791 from multiple eclipsing binary members. I. Measurements, methods, and first results
Earlier measurements of the masses and radii of the detached eclipsing binary
V20 in the open cluster NGC 6791 were accurate enough to demonstrate that there
are significant differences between current stellar models. Here we improve on
those results and add measurements of two additional detached eclipsing
binaries, the cluster members V18 and V80. The enlarged sample sets much
tighter constraints on the properties of stellar models than has hitherto been
possible, thereby improving both the accuracy and precision of the cluster age.
We employed (i) high-resolution UVES spectroscopy of V18, V20 and V80 to
determine their spectroscopic effective temperatures, [Fe/H] values, and
spectroscopic orbital elements, and (ii) time-series photometry from the Nordic
Optical Telescope to obtain the photometric elements. The masses and radii of
the V18 and V20 components are found to high accuracy, with errors on the
masses in the range 0.27-0.36% and errors on the radii in the range 0.61-0.92%.
V80 is found to be magnetically active, and more observations are needed to
determine its parameters accurately. The metallicity of NGC 6791 is measured
from disentangled spectra of the binaries and a few single stars to be [Fe/H]=
+0.29 \pm 0.03 (random) \pm 0.07 (systematic). The cluster reddening and
apparent distance modulus are found to be E(B - V) = 0.160 \pm 0.025 and (m -
M)V = 13.51 \pm 0.06 . A first model comparison shows that we can constrain the
helium content of the NGC 6791 stars, and thus reach a more accurate age than
previously possible. It may be possible to constrain additional parameters, in
particular the C, N, and O abundances. This will be investigated in paper II.Comment: Accepted for publication in A&
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A multi-modal data resource for investigating topographic heterogeneity in patient-derived xenograft tumors.
Patient-derived xenografts (PDXs) are an essential pre-clinical resource for investigating tumor biology. However, cellular heterogeneity within and across PDX tumors can strongly impact the interpretation of PDX studies. Here, we generated a multi-modal, large-scale dataset to investigate PDX heterogeneity in metastatic colorectal cancer (CRC) across tumor models, spatial scales and genomic, transcriptomic, proteomic and imaging assay modalities. To showcase this dataset, we present analysis to assess sources of PDX variation, including anatomical orientation within the implanted tumor, mouse contribution, and differences between replicate PDX tumors. A unique aspect of our dataset is deep characterization of intra-tumor heterogeneity via immunofluorescence imaging, which enables investigation of variation across multiple spatial scales, from subcellular to whole tumor levels. Our study provides a benchmark data resource to investigate PDX models of metastatic CRC and serves as a template for future, quantitative investigations of spatial heterogeneity within and across PDX tumor models
The ‘lonely raver’: music livestreams during COVID-19 as a hotline to collective consciousness?
This paper offers an explorative analysis of the online social practices of
livestreamed concerts as one of the most popular cultural outlets during the
COVID-19 imposed ‘lockdown’ in Europe. Ritual theory is used to investigate
the potential of these virtual concerts in generating a collective
consciousness, and the related feelings of social solidarity and resilience,
specifically important in times of physical isolation. Through a thematic
content analysis of the comments (n = 1501) posted during livestreamed
techno concerts in the Netherlands, we find that both old and new ritual
actions are used to form online communities. While these ritual activities mark
participation and remind members of a previous collective feeling, the
omission of visceral elements of a physical audience hampers the
establishment of a renewed sense of social solidarity
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