19,447 research outputs found
Pentaquark implications for exotic mesons
If the exotic baryon is a correlated with , then there should exist an exotic meson, GeV with width MeV. The
may be broad members of {\bf 10} \10bar in such a
picture. Vector mesons in the 1.4 - 1.7GeV mass range are also compared with
this picture
Cluster Winds Blow along Supercluster Axes
Within Abell galaxy clusters containing wide-angle tailed radio sources,
there is evidence of a ``prevailing wind'' which directs the WAT jets. We study
the alignment of WAT jets and nearby clusters to test the idea that this wind
may be a fossil of drainage along large-scale supercluster axes. We also test
this idea with a study of the alignment of WAT jets and supercluster axes.
Statistical test neighbours indicate no alignment of WAT jets towards nearest
clusters, but do indicate approximately 98% confidence in alignment with the
long axis of the supercluster in which the cluster lies. We find a preferred
scale for such superclusters of order 25 Mpc .Comment: Latex, 5 pages, with 5 postscript figures. To be published in MNRAS.
Slight revisions to coincide with journal text. Linked to color image at
http://kusmos.phsx.ukans.edu/~melott/images/A2634SUW.jp
Contemporary Seismicity in and Around the Yakima Fold-and-Thrust Belt in Eastern Washington
We examined characteristics of routinely cataloged seismicity from 1970 to the present in and around the Yakima fold-and-thrust belt (YFTB) in eastern Washington to determine if the characteristics of contemporary seismicity provide clues about regional-scale active tectonics or about more localized, near-surface processes. We employed new structural and hydrologic models of the Columbia River basalts (CRB) and found that one-third to one-half of the cataloged earthquakes occur within the CRB and that these CRB earthquakes exhibit significantly more clustered, and swarmlike, behavior than those outside. These results and inferences from published studies led us to hypothesize that clustered seismicity is likely associated with hydrologic changes in the CRB, which hosts the regional aquifer system. While some general features of the regional groundwater system support this hypothesis, seismicity patterns and mapped long-term changes in groundwater levels and present-day irrigation neither support nor refute it. Regional tectonic processes and crustal-scale structures likely influence the distribution of earthquakes both outside and within the CRB as well. We based this inference on qualitatively assessed alignments between the dominant northwest trends in the geologic structure and the seismicity generally and between specific faults and characteristics of the 2009 Wooded Island swarm and aseismic slip, which is the only cluster studied in detail and the most vigorous since regional monitoring began.USGS-NAGTGeological Science
Mixing fuel particles for space combustion research using acoustics
Part of the microgravity science to be conducted aboard the Shuttle (STS) involves combustion using solids, particles, and liquid droplets. The central experimental facts needed for characterization of premixed quiescent particle cloud flames cannot be adequately established by normal gravity studies alone. The experimental results to date of acoustically mixing a prototypical particulate, lycopodium, in a 5 cm diameter by 75 cm long flame tube aboard a Learjet aircraft flying a 20 sec low gravity trajectory are described. Photographic and light detector instrumentation combine to measure and characterize particle cloud uniformity
Psychosocial impact of involvement in the special olympics
Existing evidence suggests that people with intellectual disabilities are vulnerable to low self-esteem leading to additional psychosocial issues such as social exclusion and stress. Previous research into the involvement of Special Olympics (SO) of people with intellectual disabilities has indicted positive psychosocial outcomes. Involvement in sport is known generally to have psychological and social benefits.
This study aimed to compare the psychosocial impact of involvement in sport through the SO to no or limited sports involvement, for a sample of people with intellectual disabilities. A cross sectional design was employed comparing three groups, SO, Mencap Sports, and Mencap No Sports on the variables: Self-esteem, quality of life, stress levels and social networks. One hundred and one participants were recruited either through the SO or Mencap. Data were collected through the completion of validated questionnaires by one to one interviews with the participants. Analysis revealed that self-esteem, quality of life, and stress were all significantly associated with SO involvement. Logistic regression analysis was used to explore whether scores on these variables were able to predict group membership. Self-esteem was found to be a significant predictor of group membership, those in the SO having the highest self-esteem.
The findings provide further evidence of a positive association between sport involvement and increased psychological wellbeing, especially for those involved in the SO. The implications of these findings for practice and future research into the relationship between sport and psychological wellbeing within the learning disabled population are considered
Molecular profiling of resident and infiltrating mononuclear phagocytes during rapid adult retinal degeneration using single-cell RNA sequencing.
Neuroinflammation commonly accompanies neurodegeneration, but the specific roles of resident and infiltrating immune cells during degeneration remains controversial. Much of the difficulty in assessing myeloid cell-specific functions during disease progression arises from the inability to clearly distinguish between activated microglia and bone marrow-derived monocytes and macrophages in various stages of differentiation and activation within the central nervous system. Using an inducible model of photoreceptor cell death, we investigated the prevalence of infiltrating monocytes and macrophage subpopulations after the initiation of degeneration in the mouse retina. In vivo retinal imaging revealed infiltration of CCR2+ leukocytes across retinal vessels and into the parenchyma within 48 hours of photoreceptor degeneration. Immunohistochemistry and flow cytometry confirmed and characterized these leukocytes as CD11b+CD45+ cells. Single-cell mRNA sequencing of the entire CD11b+CD45+ population revealed the presence of resting microglia, activated microglia, monocytes, and macrophages as well as 12 distinct subpopulations within these four major cell classes. Our results demonstrate a previously immeasurable degree of molecular heterogeneity in the innate immune response to cell-autonomous degeneration within the central nervous system and highlight the necessity of unbiased high-throughput and high-dimensional molecular techniques like scRNAseq to understand the complex and changing landscape of immune responders during disease progression
Pencil-Beam Surveys for Faint Trans-Neptunian Objects
We have conducted pencil-beam searches for outer solar system objects to a
limiting magnitude of R ~ 26. Five new trans-neptunian objects were detected in
these searches. Our combined data set provides an estimate of ~90
trans-neptunian objects per square degree brighter than ~ 25.9. This estimate
is a factor of 3 above the expected number of objects based on an extrapolation
of previous surveys with brighter limits, and appears consistent with the
hypothesis of a single power-law luminosity function for the entire
trans-neptunian region. Maximum likelihood fits to all self-consistent
published surveys with published efficiency functions predicts a cumulative sky
density Sigma(<R) obeying log10(Sigma) = 0.76(R-23.4) objects per square degree
brighter than a given magnitude R.Comment: Accepted by AJ, 18 pages, including 6 figure
Substructure in clusters containing wide-angle tailed radio galaxies. I. New redshifts
We present new redshifts and positions for 635 galaxies in nine rich clusters
containing Wide-Angle Tailed (WAT) radio galaxies. Combined with existing data,
we now have a sample of 18 WAT-containing clusters with more than 10 redshifts.
This sample contains a substantial portion of the WAT clusters in the VLA 20 cm
survey of Abell clusters, including 75% of WAT clusters in the complete survey
(z0.09. It is a representative sample
which should not contain biases other than selection by radio morphology. We
graphically present the new data using histograms and sky maps. A
semi-automated procedure is used to search for emission lines in the spectra in
order to add and verify galaxy redshifts. We find that the average apparent
fraction of emission line galaxies is about 9% in both the clusters and the
field. We investigate the magnitude completeness of our redshift surveys with
CCD data for a test case, Abell 690. This case indicates that our galaxy target
lists are deeper than the detection limit of a typical MX exposure, and they
are 82% complete down to R=19.0. The importance of the uniformity of the
placement of fibers on targets is posited, and we evaluate this in our
datasets. We find some cases of non-uniformities which may influence dynamical
analyses. A second paper will use this database to look for correlations
between the WAT radio morphology and the cluster's dynamical state.Comment: 15 pages, 5 figures, 7 tables. To appear in the Astronomical Journa
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