5,716 research outputs found
System for testing bearings
Disclosed here is a system for testing bearings wherein a pair of spaced bearings provides support for a shaft on which is mounted a bearing to be tested, this bearing being mounted in a bearing holder spaced from and in alignment with the pair of bearings. The bearing holder is provided with an annular collar positioned in an opening in the bearing holder for holding the bearing to be tested. A screw threaded through the bearing holder into engagement with the annular collar can be turned to force the collar radially out of alignment with the pair of bearings to apply a radial load to the bearing
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CO2 conversion to phenyl isocyanates by uranium(vi) bis(imido) complexes.
Uranium(vi) trans-bis(imido) complexes [U(κ4-{(tBu2ArO)2Me2-cyclam})(NPh)(NPhR)] react with CO2 to eliminate phenyl isocyanates and afford uranium(vi) trans-[O[double bond, length as m-dash]U[double bond, length as m-dash]NR]2+ complexes, including [U(κ4-{(tBu2ArO)2Me2-cyclam})(NPh)(O)] that was crystallographically characterized. DFT studies indicate that the reaction proceeds by endergonic formation of a cycloaddition intermediate; the secondary reaction to form a dioxo uranyl complex is both thermodynamically and kinetically hindered
Porous silica spheres as indoor air pollutant scavengers
Porous silica spheres were investigated for their effectiveness in removing typical indoor air pollutants, such as aromatic and carbonyl-containing volatile organic compounds (VOCs), and compared to the commercially available polymer styrene-divinylbenzene (XAD-4). The silica spheres and the XAD-4 resin were coated on denuder sampling devices and their adsorption efficiencies for volatile organic compounds evaluated using an indoor air simulation chamber. Real indoor sampling was also undertaken to evaluate the affinity of the silica adsorbents for a variety of indoor VOCs. The silica sphere adsorbents were found to have a high affinity for polar carbonyls and found to be more efficient than the XAD-4 resin at adsorbing carbonyls in an indoor environment
How benign is sickle cell trait?
This is the final version of the article. It first appeared from Elsevier at http://dx.doi.org/10.1016/j.ebiom.2016.08.023
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Lipid metabolism in terminal erythropoiesis.
In this issue of Blood, Huang et al have provided evidence that altered lipid metabolism is critical for terminal erythropoiesis. A key role is proposed for the PHOSPHO1 gene product, a phosphocholine phosphatase. PHOSPHO1 knockouts (KOs) showed reduced erythroblast proliferation and enucleation in both mice and human erythroid tissues, apparently through energy depletion mediated via inhibition of oxidative phosphorylation of fatty acids and reduced adenosine triphosphate (ATP) production in late glycolysis. This work emphasizes that altered expression of genes involving lipid metabolism are important during late red cell maturation
The evolution of the natural killer complex; a comparison between mammals using new high-quality genome assemblies and targeted annotation.
Natural killer (NK) cells are a diverse population of lymphocytes with a range of biological roles including essential immune functions. NK cell diversity is in part created by the differential expression of cell surface receptors which modulate activation and function, including multiple subfamilies of C-type lectin receptors encoded within the NK complex (NKC). Little is known about the gene content of the NKC beyond rodent and primate lineages, other than it appears to be extremely variable between mammalian groups. We compared the NKC structure between mammalian species using new high-quality draft genome assemblies for cattle and goat; re-annotated sheep, pig, and horse genome assemblies; and the published human, rat, and mouse lemur NKC. The major NKC genes are largely in the equivalent positions in all eight species, with significant independent expansions and deletions between species, allowing us to propose a model for NKC evolution during mammalian radiation. The ruminant species, cattle and goats, have independently evolved a second KLRC locus flanked by KLRA and KLRJ, and a novel KLRH-like gene has acquired an activating tail. This novel gene has duplicated several times within cattle, while other activating receptor genes have been selectively disrupted. Targeted genome enrichment in cattle identified varying levels of allelic polymorphism between the NKC genes concentrated in the predicted extracellular ligand-binding domains. This novel recombination and allelic polymorphism is consistent with NKC evolution under balancing selection, suggesting that this diversity influences individual immune responses and may impact on differential outcomes of pathogen infection and vaccination
Are Red Tidal Features Unequivocal Signatures of Major Dry Mergers?
We use a cosmological numerical simulation to study the tidal features
produced by a minor merger with an elliptical galaxy. We find that the
simulated tidal features are quantitatively similar to the red tidal features,
i.e., dry tidal features, recently found in deep images of elliptical galaxies
at intermediate redshifts. The minor merger in our simulation does not trigger
star formation due to active galactic nuclei heating. Therefore, both the tidal
features and the host galaxy are red, i.e. a dry minor merger. The stellar mass
of the infalling satellite galaxy is about 10^10 Msun, and the tidal debris
reach the surface brightness of mu_R~27 mag arcsec^-2. Thus, we conclude that
tidal debris from minor mergers can explain the observed dry tidal features in
ellipticals at intermediate redshifts, although other mechanisms (such as major
dry mergers) may also be important.Comment: 7 pages, 7 figures, accepted for publication in Ap
New forms of mobilization, new people mobilized? Evidence from the Comparative Study of Electoral Systems
Mobilization efforts by parties and candidates during election campaigns tend to reach
those who are more likely to vote in the first place. This is thought to be particularly
consequential for turnout among the young. Harder and less cost-effective to reach, young
adults are less mobilized and vote less often, creating a vicious circle of demobilization.
However, new forms of political communication — including online and text messaging —
have created expectations this circle might be broken. Is this happening? We examine data
from Module 4 of the CSES surveys, looking at the prevalence of different types of party
contacts in 38 countries, the profile of voters who are reached, and the effects of these
efforts on turnout. New forms of party contacting do matter for turnout and partially reduce
the age gap in contacting, but still fail to compensate for the much larger differentials that
persist in traditional forms of contacting.info:eu-repo/semantics/publishedVersio
Inter-transcriber reliability for two systems of prosodic annotation: ToBI (Tones and Break Indices) and RaP (Rhythm and Pitch)
Speech researchers often rely on human annotation of prosody to generate data to test hypotheses and generate models. We present an overview of two prosodic annotation systems: ToBI (Tones and Break Indices) (Silverman et al., 1992), and RaP (Rhythm and Pitch) (Dilley & Brown, 2005), which was designed to address several limitations of ToBI. The paper reports two large-scale studies of inter-transcriber reliability for ToBI and RaP. Comparable reliability for both systems was obtained for a variety of prominence- and boundary-related agreement categories. These results help to establish RaP as an alternative to ToBI for research and technology applicationsNational Science Foundation (U.S.) (NSF grant BCS 0847653
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