1,455 research outputs found
Bjerrum pairing correlations at charged interfaces
Electrostatic correlations play a fundamental role in aqueous solutions. In
this letter, we identify transverse and lateral correlations as two mutually
exclusive regimes. We show that the transverse regime leads to binding by
generalization of Bjerrum pair formation theory, yielding binding constants
from first-principle statistical-mechanical calculations. We compare our
theoretical predictions with experiments on charged membranes and Langmuir
monolayers and find good agreement. We contrast our approach with existing
theories in the strong-coupling limit and on charged modulated interfaces, and
discuss different scenarios that lead to charge reversal and equal-sign
attraction by macro-ions.Comment: 7 pages, 4 figure
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Brief behavioural activation for adolescent depression: working with complexity and risk
Given the long-term negative outcomes associated with depression in adolescence, there is a pressing need to develop brief, evidence based treatments that are accessible to more young people experiencing low mood. Behavioural Activation (BA) is an effective treatment for adult depression, however little research has focused on the use of BA with depressed adolescents, particularly with briefer forms of BA. In this article we outline an adaptation of brief Behavioral Activation Treatment of Depression (BATD) designed for adolescents and delivered in eight sessions (Brief BA). This case example illustrates how a structured, brief intervention was useful for a depressed young person with a number of complicating and risk factors
CN Bimodality at Low Metallicity: The Globular Cluster M53
We present low resolution UV-blue spectroscopic observations of red giant
stars in the globular cluster M53 ([Fe/H]=-1.84), obtained to study primordial
abundance variations and deep mixing via the CN and CH absorption bands. The
metallicity of M53 makes it an attractive target: a bimodal distribution of
3883 angstrom CN bandstrength is common in moderate- and high-metallicity
globular clusters ([Fe/H] > -1.6) but unusual in those of lower metallicity
([Fe/H] < -2.0). We find that M53 is an intermediate case, and has a broad but
not strongly bimodal distribution of CN bandstrength, with CN and CH
bandstrengths anticorrelated in the less-evolved stars. Like many other
globular clusters, M53 also exhibits a general decline in CH bandstrength and
[C/Fe] abundance with rising luminosity on the red giant branch.Comment: 8 pages including 11 figures and 1 table, accepted by PAS
Sleep and fatigue in newly graduated nursesâExperiences and strategies for handling shiftwork
Properties of the Meson at Finite Temperature and Density
The mass shift, width broadening, and spectral density for the meson
in a heat bath of nucleons and pions is calculated using a general formula
which relates the self-energy to the forward scattering amplitude. We use
experimental data to saturate the scattering amplitude at low energies with
resonances and include a background Pomeron term, while at high energies a
Regge parameterization is used. The peak of the spectral density is little
shifted from its vacuum position, but the width is considerably increased due
to collisional broadening. At normal nuclear matter density and a temperature
of 150 MeV the spectral density of the meson has a width of 140 MeV.
Zero temperature nuclear matter is also discussed.Comment: 5 pages revtex4, 3 figur
The Asymptotic Giant Branches of GCs: Selective Entry Only
The handful of available observations of AGB stars in Galactic Globular
Clusters suggest that the GC AGB populations are dominated by cyanogen-weak
stars. This contrasts strongly with the distributions in the RGB (and other)
populations, which generally show a 50:50 bimodality in CN band strength. If it
is true that the AGB populations show very different distributions then it
presents a serious problem for low mass stellar evolution theory, since such a
surface abundance change going from the RGB to AGB is not predicted by stellar
models. However this is only a tentative conclusion, since it is based on very
small AGB sample sizes. To test whether this problem really exists we have
carried out an observational campaign specifically targeting AGB stars in GCs.
We have obtained medium resolution spectra for about 250 AGB stars across 9
Galactic GCs using the multi-object spectrograph on the AAT (2df/AAOmega). We
present some of the preliminary findings of the study for the second parameter
trio of GCs: NGC 288, NGC 362 and NGC 1851. The results indeed show that there
is a deficiency of stars with strong CN bands on the AGB. To confirm that this
phenomenon is robust and not just confined to CN band strengths and their
vagaries, we have made observations using FLAMES/VLT to measure elemental
abundances for NGC 6752.We present some initial results from this study also.
Our sodium abundance results show conclusively that only a subset of stars in
GCs experience the AGB phase of evolution. This is the first direct, concrete
confirmation of the phenomenon.Comment: 4 pages, to appear in conference proceedings of "Reading the book of
globular clusters with the lens of stellar evolution", Rome, 26-28 November
201
Upgrading short read animal genome assemblies to chromosome level using comparative genomics and a universal probe set
Most recent initiatives to sequence and assemble new speciesâ genomes de-novo fail to achieve the ultimate endpoint to produce a series of contigs, each representing one whole chromosome. Even the best-assembled genomes (using contemporary technologies) consist of sub-chromosomal sized scaffolds. To circumvent this problem, we developed a novel approach that combines computational algorithms to merge scaffolds into chromosomal fragments, scaffold verification by PCR and physical mapping to chromosomes. Multi genome-alignment-guided probe selection led to the development of a set of universal avian BAC clones that permit rapid anchoring of multiple scaffold loci to chromosomes on all avian genomes. As proof of principle we assembled genomes of the pigeon (Columbia livia) and peregrine falcon (Falco peregrinus) to chromosome level comparable, in continuity, to avian reference genomes. Both species are of interest for breeding, cultural, food and/or environmental reasons. Pigeon has a typical avian karyotype (2n=80) while falcon (2n=50) is highly rearranged compared to the avian ancestor. Using chromosome breakpoint data, we established that avian interchromosomal breakpoints appear in the regions of low density of conserved non-coding elements (CNEs) and that the chromosomal fission sites are further limited to long CNE âdesertsâ. This corresponds with fission being the rarest type of rearrangement in avian genome evolution. High-throughput multiple hybridization and rapid capture strategies using the current BAC set provide the basis for assembling numerous avian (and possibly other reptilian) species while the overall strategy for scaffold assembly and mapping provides the basis for an approach that could be applied to any animal genome
Calibrations of Atmospheric Parameters Obtained from the First Year of SDSS-III APOGEE Observations
The SDSS-III Apache Point Observatory Galactic Evolution Experiment (APOGEE)
is a three year survey that is collecting 100,000 high-resolution spectra in
the near-IR across multiple Galactic populations. To derive stellar parameters
and chemical compositions from this massive data set, the APOGEE Stellar
Parameters and Chemical Abundances Pipeline (ASPCAP) has been developed. Here,
we describe empirical calibrations of stellar parameters presented in the first
SDSS-III APOGEE data release (DR10). These calibrations were enabled by
observations of 559 stars in 20 globular and open clusters. The cluster
observations were supplemented by observations of stars in NASA's Kepler field
that have well determined surface gravities from asteroseismic analysis. We
discuss the accuracy and precision of the derived stellar parameters,
considering especially effective temperature, surface gravity, and metallicity;
we also briefly discuss the derived results for the abundances of the
alpha-elements, carbon, and nitrogen. Overall, we find that ASPCAP achieves
reasonably accurate results for temperature and metallicity, but suffers from
systematic errors in surface gravity. We derive calibration relations that
bring the raw ASPCAP results into better agreement with independently
determined stellar parameters. The internal scatter of ASPCAP parameters within
clusters suggests that, metallicities are measured with a precision better than
0.1 dex, effective temperatures better than 150 K, and surface gravities better
than 0.2 dex. The understanding provided by the clusters and Kepler giants on
the current accuracy and precision will be invaluable for future improvements
of the pipeline.Comment: 40 pages, 15 figures, 4 tables, accepted to A
âIt stays with youâ: multiple evocative representations of dance and future possibilities for studies in sport and physical cultures
This article considers the integration of arts-based representations via poetic narratives together with artistic representation on dancing embodiment so as to continue an engagement with debates regarding multiple forms/representations. Like poetry, visual images are unique and can evoke particular kinds of emotional and visceral responses, meaning that alternative representational forms can resonate in different and powerful ways. In the article, we draw on grandparent-grandchild interactions, narrative poetry, and artistic representations of dance in order to illustrate how arts-based methods might synergise to offer new ways of âknowingâ and âseeingâ. The expansion of the visual arts into interdisciplinary methodological innovations is a relatively new, and sometimes contentious approach, in studies of sport and exercise. We raise concerns regarding the future for more arts-based research in the light of an ever-changing landscape of a neoliberal university culture that demands high productivity in reductionist terms of what counts as âoutputâ, often within very restricted time-frames. Heeding feminist calls for âslow academiesâ that attempt to âchangeâ time collectively, and challenge the demands of a fast-paced audit culture, we consider why it is worth enabling creative and arts-based methods to continue to develop and flourish in studies of sport, exercise and health, despite the mounting pressures to âperformâ
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