7,498 research outputs found
Welcome back, Polaris the Cepheid
For about 100 years the amplitude of the 4-day pulsation in Polaris has
decreased. We present new results showing a significant increase in the
amplitude based on 4.5 years of continuous monitoring from the ground and with
two satellite missions.Comment: 5 pages; to appear in the proceedings of the "Cool Stars 15" workshop
held at St Andrews, U
Accurate Chart Latticing for Loran-C
Unless the Loran-C lattice has much the same accuracy as any other feature shown, the chart is out of balance. There is not much point in charting hazards with great precision if the mariner must allow a large margin for positioning error in his navaid. The Canadian Hydrographic Service’s calibration program aims eventually to improve our knowledge of radio wave propagation so that we can rely on a calculated lattice with only a very few check points to verify the predictions. While we work towards this, we also map the lattice in the field so that we can put it on the chart accurately now. We calibrated the Canadian West Coast Loran-C chain in the Spring of 1977, using Satnav offshore to give the ± 150 m accuracy needed for latticing small scale charts. We looked for and found the predicted coastal " phase recovery " using Trisponder and sextant fixing. And we made observations on shore by helicopter and calibration van to give propagation data for future predictions
Religiosity and Sexual Risk Behaviors Among Latina Adolescents: Trends from 1995 to 2008
Purpose: The purpose of this study was to determine trends in the influence of religiosity on sexual activity of Latina adolescents in the United States from 1995 to 2008 and to determine if differences existed between the Mexican American and other Latina groups.
Methods: The sample comprised the subset of unmarried, 15–21-year-old (mean 17 years) Latina female respondents in the 1995 (n=267), 2002 (n=306), and 2006–2008 (n=400) National Survey of Family Growth (NSFG) datasets. Associations between religiosity (importance of religion and service attendance) and history of ever having sex, number of sex partners, and age of sexual debut were investigated.
Results: Less than one half of Latinas in 1995 (44%) and in 2006–2008 (44%) reported that religion was very important to them, whereas in 2002, 50% reported it was important. Only in 1995 did Latinas who viewed religion as very important have a significantly lower level of sexual initiation. In 1995 and in 2006–2008, Latinas who held religion as very important had significantly fewer partners. In all three cohorts, the higher religious importance group had higher virgin survival rates. Across cohorts, approximately one third of respondents reported frequent religious attendance. In all cohorts, frequent attenders were less likely to have had sex, had fewer partners, and had older age at sexual debut. The survival rate as virgins for Mexican origin Latinas was higher in 1995 and 2002 compared to non-Mexican Latinas but was almost the same in 2006–2008.
Conclusions: Religiosity had a protective association with sexual activity among Latina adolescents. The association of importance of religion with sexual activity has diminished from 1995 to 2008, however, whereas the importance of service attendance has remained stable. The influence of religion was more apparent among the Latinas of Mexican origin, but this greater influence also diminished by 2006–2008
Molecular analysis of intragenic recombination at the tryptophan synthetase locus in Neurospora crassa
Fifteen different classically generated and mapped mutations at the tryptophan synthetase locus in Neurospora crassa have been characterized to the level of the primary sequence of the gene. This sequence analysis has demonstrated that intragenic recombination is accurate to order mutations within one open reading frame. While classic genetic analysis correctly ordered the mutations, the position of mutations characterized by gene sequence analysis was more accurate. A leaky mutation was found to have a wild-type primary sequence. The presence of unique polymorphisms in the primary sequence of the trp-3 gene from strain 861 confirms that it has a unique history relative to the other strains studied. Most strains that were previously shown to be immunologically nonreactive with antibody preparations raised against tryptophan synthetase protein were shown to have nonsense mutations. This work defines 14 alleles of the N. crassa trp-3 gene.Citation: "Molecular analysis of intragenic recombination at the tryptophan synthetase locus in Neurospora crassa" (December 2013) A. Wiest D. Barchers M. Eaton R. Henderson R. Schnittker K. Mccluskey. Journal of Genetics, Indian Academy of Science. Volume 92 Issue 3. 523-528.Citation: Wiest, A., . . . & McCluskey, K. (2013). Molecular analysis of intragenic recombination at the tryptophan
synthetase locus in Neurospora crassa. Journal of Genetics, 92(1), 523–528.
https://doi.org/https://doi.org/10.1007/s12041-013-0305-
The risk of extinction for birds in Great Britain
t Over the last 20 years,species priorities for bird conservation in the UK
have been guided by ‘Birds of Conservation Concern’ – an in-depth assessment
made possible by the top-class data available on the status of the UK’s birds. For
other wildlife, priorities tend to be informed by measures of extinction risk,
generated by the IUCN Regional Red List process.We carried out the first formal
IUCN assessment for birds in Great Britain. Of the 241 species assessed, 100 (43%)
had at least one population (breeding and/or non-breeding) that qualified as
Threatened using the standard IUCN Red List criteria and categories. Of 289
separate assessments of breeding or non-breeding populations, 39% qualified as
Threatened (8% Critically Endangered, 14% Endangered, 17% Vulnerable) with a
further 10% classified as Near Threatened. Both Golden Oriole Oriolus oriolus and
Fieldfare Turdus pilaris were assessed as being Critically Endangered (Possibly
Extinct) as breeding species, in addition to seven species that are already extinct
(either Extinct or Regionally Extinct). The proportion of GB birds qualifying as
Threatened was high compared with birds elsewhere in Europe and other
taxonomic groups in GB. We believe that, if similar data were available, levels of
extinction risk would be higher for other areas/taxa than is currently estimated
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Radseq dataset with 90% missing data fully resolves recent radiation of Petalidium (Acanthaceae) in the ultra-arid deserts of Namibia
Deserts, even those at tropical latitudes, often have strikingly low levels of plant diversity, particularly within genera. One remarkable exception to this pattern is the genus Petalidium (Acanthaceae), in which 37 of 40 named species occupy one of the driest environments on Earth, the Namib Desert of Namibia and neighboring Angola. To contribute to understanding this enigmatic diversity, we generated RADseq data for 47 accessions of Petalidium representing 22 species. We explored the impacts of 18 different combinations of assembly parameters in de novo assembly of the data across nine levels of missing data plus a best practice assembly using a reference Acanthaceae genome for a total of 171 sequence datasets assembled. RADseq data assembled at several thresholds of missing data, including 90% missing data, yielded phylogenetic hypotheses of Petalidium that were confidently and nearly fully resolved, which is notable given that divergence time analyses suggest a crown age for African species of 3.6–1.4 Ma. De novo assembly of our data yielded the most strongly supported and well-resolved topologies; in contrast, reference-based assembly performed poorly, perhaps due in part to moderate phylogenetic divergence between the reference genome, Ruellia speciosa, and the ingroup. Overall, we found that Petalidium, despite the harshness of the environment in which species occur, shows a net diversification rate (0.8–2.1 species per my) on par with those of diverse genera in tropical, Mediterranean, and alpine environments
The Financialization of US Higher Education
Research on financialization has been constrained by limited suitable measures for cases outside of the for-profit sector. Using the case of US higher education, we consider financialization as both increasing reliance on financial investment returns and increasing costs from transactions to acquire capital. We document returns and costs across four types of transactions: (i) revenues from endowment investments, (ii) interest payments on institutional borrowing by colleges, (iii) profits extracted by investors in for-profit colleges and (iv) interest payments on student loan borrowing by households. Estimated annual funding from endowment investments grew from 20 billion in 2012. Meanwhile financing costs grew from 48 billion in 2012, or from 5 to 9% of the total higher education spending, even as interest rates declined. Increases in financial returns, however, were concentrated at wealthy colleges whereas increases in financing costs tended to outpace returns at poorer institutions. We discuss the implications of the findings for resource allocation, organizational governance and stratification among colleges and households.1. Introduction 2. Financialization and higher education 3. Data and measures 4. College endowments and financial revenues 5. College institutional debt and interest costs 6. Proprietary colleges and profits as the costs of equity investment 7. Student loan debt and interest payments 8. Quantifying the costs of higher education financialization 9. Conclusions Supplementary material Funding Acknowledgements References Supplementary dat
The European Large Area ISO Survey II: mid-infrared extragalactic source counts
We present preliminary source counts at 6.7um and 15um from the Preliminary
Analysis of the European Large Area ISO survey, with limiting flux densities of
\~2mJy at 15um & ~1mJy at 6.7um. We separate the stellar contribution from the
extragalactic using identifications with APM sources made with the likelihood
ratio technique. We quantify the completeness & reliability of our source
extraction using (a) repeated observations over small areas, (b) cross-IDs with
stars of known spectral type, (c) detections of the PSF wings around bright
sources, (d) comparison with independent algorithms. Flux calibration at 15um
was performed using stellar IDs; the calibration does not agree with the
pre-flight estimates, probably due to effects of detector hysteresis and
photometric aperture correction. The 6.7um extragalactic counts are broadly
reproduced in the Pearson & Rowan-Robinson model, but the Franceschini et al.
(1997) model underpredicts the observed source density by ~0.5-1 dex, though
the photometry at 6.7um is still preliminary. At 15um the extragalactic counts
are in excellent agreement with the predictions of the Pearson & Rowan-Robinson
(1996), Franceschini et al. (1994), Guiderdoni et al. (1997) and the evolving
models of Xu et al. (1998), over 7 orders of magnitude in 15um flux density.
The counts agree with other estimates from the ISOCAM instrument at overlapping
flux densities (Elbaz et al. 1999), provided a consistent flux calibration is
used. Luminosity evolution at a rate of (1+z)^3, incorporating mid-IR spectral
features, provides a better fit to the 15um differential counts than (1+z)^4
density evolution. No-evolution models are excluded, and implying that below
around 10mJy at 15um the source counts become dominated by an evolving
cosmological population of dust-shrouded starbursts and/or active galaxies.Comment: MNRAS in press. 14 pages, uses BoxedEPS (included). For more
information on the ELAIS project see http://athena.ph.ic.ac.uk
Electrical properties of a-antimony selenide
This paper reports conduction mechanism in a-\sbse over a wide range of
temperature (238K to 338K) and frequency (5Hz to 100kHz). The d.c. conductivity
measured as a function of temperature shows semiconducting behaviour with
activation energy E= 0.42 eV. Thermally induced changes in the
electrical and dielectric properties of a-\sbse have been examined. The a.c.
conductivity in the material has been explained using modified CBH model. The
band conduction and single polaron hopping is dominant above room temperature.
However, in the lower temperature range the bipolaron hopping dominates.Comment: 9 pages (RevTeX, LaTeX2e), 9 psfigures, also at
http://pu.chd.nic.in/ftp/pub/san16 e-mail: gautam%[email protected]
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