4,633 research outputs found
Training School Psychology Graduate Students to Address Regional Shortages: A Distance Learning Model
Addressing the shortages of school psychologists in underserved regions of the country is critical to the profession and the communities served by its members. This article describes a school psychology satellite training program using a hybrid approach combining distance learning technologies and face-to-face classroom meetings. The purpose of this study was to describe the experiences of sixteen graduate students in a rural, Appalachian region of Ohio as members of the first two cohorts enrolled in the school psychology satellite program
Rapid Evolution of BRCA1 and BRCA2 in Humans and Other Primates
The maintenance of chromosomal integrity is an essential task of every living organism and cellular repair mechanisms exist to guard against insults to DNA. Given the importance of this process, it is expected that DNA repair proteins would be evolutionarily conserved, exhibiting very minimal sequence change over time. However, BRCA1, an essential gene involved in DNA repair, has been reported to be evolving rapidly despite the fact that many protein-altering mutations within this gene convey a significantly elevated risk for breast and ovarian cancers. Results: To obtain a deeper understanding of the evolutionary trajectory of BRCA1, we analyzed complete BRCA1 gene sequences from 23 primate species. We show that specific amino acid sites have experienced repeated selection for amino acid replacement over primate evolution. This selection has been focused specifically on humans and our closest living relatives, chimpanzees (Pan troglodytes) and bonobos (Pan paniscus). After examining BRCA1 polymorphisms in 7 bonobo, 44 chimpanzee, and 44 rhesus macaque (Macaca mulatta) individuals, we find considerable variation within each of these species and evidence for recent selection in chimpanzee populations. Finally, we also sequenced and analyzed BRCA2 from 24 primate species and find that this gene has also evolved under positive selection. Conclusions: While mutations leading to truncated forms of BRCA1 are clearly linked to cancer phenotypes in humans, there is also an underlying selective pressure in favor of amino acid-altering substitutions in this gene. A hypothesis where viruses are the drivers of this natural selection is discussed.National Institutes of Health R01-GM-093086, 8U42OD011197-13National Science Foundation BCS-07115972Burroughs Wellcome FundMolecular Bioscience
How to identify a Strange Star
Contrary to young neutron stars, young strange stars are not subject to the
r-mode instability which slows rapidly rotating, hot neutron stars to rotation
periods near 10 ms via gravitational wave emission. Young millisecond pulsars
are therefore likely to be strange stars rather than neutron stars, or at least
to contain significant quantities of quark matter in the interior.Comment: 4 pages, 1 figur
Second Order Thermal Corrections to Electron Wavefunction
Second order perturbative corrections to electron wavefunction are calculated
here at generalized temperature, for the first time. This calculation is
important to prove the renormalizeability of QED through order by order
cancellation of singularities at higher order. This renormalized wavefunction
could be used to calculate the particle processes in the extremely hot systems
such as the very early universe and the stellar cores. We have to re-write the
second order thermal correction to electron mass in a convenient way to be able
to calculate the wavefunction renormalization constant. A procedure for
integrations of hot loop momenta before the cold loop momenta integration is
maintained throughout to be able to remove hot singularities in an appropriate
way. Our results, not only includes the intermediate temperatures T m (where m
is the electron mass), the limits of high temperature T>>m and low temperature
T<<m are also retrievable. A comparison is also done with the existing results.Comment: 12 Pages and 1 figure; Submitted for publicatio
Neutrino Interactions in Hot and Dense Matter
We study the charged and neutral current weak interaction rates relevant for
the determination of neutrino opacities in dense matter found in supernovae and
neutron stars. We establish an efficient formalism for calculating differential
cross sections and mean free paths for interacting, asymmetric nuclear matter
at arbitrary degeneracy. The formalism is valid for both charged and neutral
current reactions. Strong interaction corrections are incorporated through the
in-medium single particle energies at the relevant density and temperature. The
effects of strong interactions on the weak interaction rates are investigated
using both potential and effective field-theoretical models of matter. We
investigate the relative importance of charged and neutral currents for
different astrophysical situations, and also examine the influence of
strangeness-bearing hyperons. Our findings show that the mean free paths are
significantly altered by the effects of strong interactions and the
multi-component nature of dense matter. The opacities are then discussed in the
context of the evolution of the core of a protoneutron star.Comment: 41 pages, 25 figure
Massive migration from the steppe is a source for Indo-European languages in Europe
We generated genome-wide data from 69 Europeans who lived between 8,000-3,000
years ago by enriching ancient DNA libraries for a target set of almost four
hundred thousand polymorphisms. Enrichment of these positions decreases the
sequencing required for genome-wide ancient DNA analysis by a median of around
250-fold, allowing us to study an order of magnitude more individuals than
previous studies and to obtain new insights about the past. We show that the
populations of western and far eastern Europe followed opposite trajectories
between 8,000-5,000 years ago. At the beginning of the Neolithic period in
Europe, ~8,000-7,000 years ago, closely related groups of early farmers
appeared in Germany, Hungary, and Spain, different from indigenous
hunter-gatherers, whereas Russia was inhabited by a distinctive population of
hunter-gatherers with high affinity to a ~24,000 year old Siberian6 . By
~6,000-5,000 years ago, a resurgence of hunter-gatherer ancestry had occurred
throughout much of Europe, but in Russia, the Yamnaya steppe herders of this
time were descended not only from the preceding eastern European
hunter-gatherers, but from a population of Near Eastern ancestry. Western and
Eastern Europe came into contact ~4,500 years ago, as the Late Neolithic Corded
Ware people from Germany traced ~3/4 of their ancestry to the Yamnaya,
documenting a massive migration into the heartland of Europe from its eastern
periphery. This steppe ancestry persisted in all sampled central Europeans
until at least ~3,000 years ago, and is ubiquitous in present-day Europeans.
These results provide support for the theory of a steppe origin of at least
some of the Indo-European languages of Europe
Canoe binds RanGTP to promote PinsTPR/Mud-mediated spindle orientation
The scaffolding protein Canoe regulates spindle orientation by binding to RanGTP and recruiting RanGTP and Mud to the cell cortex
Spin-Isospin Structure and Pion Condensation in Nucleon Matter
We report variational calculations of symmetric nuclear matter and pure
neutron matter, using the new Argonne v18 two-nucleon and Urbana IX
three-nucleon interactions. At the equilibrium density of 0.16 fm^-3 the
two-nucleon densities in symmetric nuclear matter are found to exhibit a
short-range spin-isospin structure similar to that found in light nuclei. We
also find that both symmetric nuclear matter and pure neutron matter undergo
transitions to phases with pion condensation at densities of 0.32 fm^-3 and 0.2
fm^-3, respectively. Neither transtion occurs with the Urbana v14 two-nucleon
interaction, while only the transition in neutron matter occurs with the
Argonne v14 two-nucleon interaction. The three-nucleon interaction is required
for the transition to occur in symmetric nuclear matter, whereas the the
transition in pure neutron matter occurs even in its absence. The behavior of
the isovector spin-longitudinal response and the pion excess in the vicinity of
the transition, and the model dependence of the transition are discussed.Comment: 44 pages RevTeX, 15 postscript figures. Minor modifications to
original postin
Pliocene-Quaternary crustal melting in central and northern Tibet and insights into crustal flow
There is considerable controversy over the nature of geophysically recognized low-velocity-high-conductivity zones (LV-HCZs) within the Tibetan crust, and their role in models for the development of the Tibetan Plateau. Here we report petrological and geochemical data on magmas erupted 4.7-0.3 Myr ago in central and northern Tibet, demonstrating that they were generated by partial melting of crustal rocks at temperatures of 700-1,050°C and pressures of 0.5-1.5 GPa. Thus Pliocene-Quaternary melting of crustal rocks occurred at depths of 15-50 km in areas where the LV-HCZs have been recognized. This provides new petrological evidence that the LV-HCZs are sources of partial melt. It is inferred that crustal melting played a key role in triggering crustal weakening and outward crustal flow in the expansion of the Tibetan Plateau
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