4,388 research outputs found
Identifying Blue Horizontal Branch Stars Using the z Filter
In this paper we present a new method for selecting blue horizontal branch
(BHB) candidates based on color-color photometry. We make use of the Sloan
Digital Sky Survey z band as a surface gravity indicator and show its value for
selecting BHB stars from quasars, white dwarfs and main sequence A type stars.
Using the g, r, i, and z bands, we demonstrate that extraction accuracies on
par with more traditional u, g, and r photometric selection methods may be
achieved. We also show that the completeness necessary to probe major Galactic
structure may be maintained. Our new method allows us to efficiently select BHB
stars from photometric sky surveys that do not include a u band filter such as
the Panoramic Survey Telescope and Rapid Response System.Comment: Accepted for publication in The Astronomical Journa
Red Runaways: Hypervelocity Stars, Hills Ejecta and Other Outliers in the F-M Star Regime
In this paper we analyze a sample of metal-rich (>-0.8 dex) main sequence
stars in the extended solar neighborhood, investigating kinematic outliers from
the background population. The data, which are taken from the Sloan Digital Sky
Survey, are kinematically profiled as a function of distance from the Galactic
plane using full six dimensional phase space information. Each star is examined
in the context of these kinematic profiles and likelihoods are assigned to
quantify whether a star matches the underlying profile. Since some of these
stars are likely to have been ejected from the disc, we trace back their orbits
in order to determine potential ejection radii. We find that objects with low
probability (i.e. `outliers') are typically more metal poor, faster and, most
importantly, have a tendency to originate from the inner Galaxy compared to the
underlying population.
We also compose a sample of stars with velocities exceeding the local escape
velocity. Although we do not discount that our sample could be contaminated by
objects with spurious proper motions, a number of stars appear to have been
ejected from the disc with exceptionally high velocities. Some of these are
consistent with being ejected from the spiral arms and hence are a rich
resource for further study. Finally we look at objects whose orbits are
consistent with them being ejected at high speeds from the Galactic center. Of
these objects we find that one, J135855.65+552538.19, is inconsistent with
halo, bulge and disk kinematics and could plausibly have been ejected from the
Galactic nucleus via a Hills mechanism.Comment: 17 Pages, 12 Figures, Accepted to A
Non-local dispersal
We consider a model of spatial spread that has applications in both material science and biology. The classical models are based upon partial differential equations, in particular reaction-diffusion equations. Here the dispersal term is given in terms of an integral operator and we restrict ourselves to the scalar case
Systematic reviews of complementary therapies – an annotated bibliography. Part 2: Herbal medicine
Background Complementary therapies are widespread but controversial. We aim to provide a comprehensive collection and a summary of systematic reviews of clinical trials in three major complementary therapies (acupuncture, herbal medicine, homeopathy). This article is dealing with herbal medicine. Potentially relevant reviews were searched through the register of the Cochrane Complementary Medicine Field, the Cochrane Library, Medline, and bibliographies of articles and books. To be included articles had to review prospective clinical trials of herbal medicines; had to describe review methods explicitly; had to be published; and had to focus on treatment effects. Information on conditions, interventions, methods, results and conclusions was extracted using a pre-tested form and summarized descriptively. Results From a total of 79 potentially relevant reviews pre-selected in the screening process 58 met the inclusion criteria. Thirty of the reports reviewed ginkgo (for dementia, intermittent claudication, tinnitus, and macular degeneration), hypericum (for depression) or garlic preparations (for cardiovascular risk factors and lower limb atherosclerosis). The quality of primary studies was criticized in the majority of the reviews. Most reviews judged the available evidence as promising but definitive conclusions were rarely possible. Conclusions Systematic reviews are available on a broad range of herbal preparations prescribed for defined conditions. There is very little evidence on the effectiveness of herbalism as practised by specialist herbalists who combine herbs and use unconventional diagnosis
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Tom Vickers, Gary Craig and Karl Atkin (2013), ‘Addressing Ethnicity in Social Care Research’, Social Policy and Administration, 47 (3), June, 310–26
This article surveys recent developments in relation to the dimensions of ethnicity and ethnic disadvantage in social policy research and practice, with a focus on social care. While there has been limited increase in attention to ethnicity within general policy discussion and increasing sophistication within specialist debates, advances in theory and methodology have largely failed to penetrate the mainstream of research, let alone policy or practice. We argue for a more focussed consideration of ethnicity and ethnic disadvantage at all levels. Failure to do so creates the risk of social policy research being left behind in understanding rapid changes in ethnic minority demographics and patterns of migration, and increasing disadvantage to minorities
An automated GC/MS system for the analysis of volatile and semi-volatile organic compounds in water
This paper describes a GC/MS system capable of performing Volatile Organic Analysis on liquids, solids, and air. When combined with a syringe auto-injector, the system is completely automated for both volatile and semi-volatile analyses. An OI Analytical Model 4551 Vial Multisampler and an OI Analytical DPM-16 Multisampler are interfaced and then connected to an OI Analytical Model 4560 Sample Concentrator, an HP Model 5971 MSD, an HP Model 7673 Auto-Injector, and an HP Model 5890 Series II GC to form a multi-tasking GC/MS system. This system is shown to allow greater versatility in the laboratory
Terpenoid metabolic engineering in photosynthetic microorganisms
© 2018 by the authors. Licensee MDPI, Basel, Switzerland. Terpenoids are a group of natural products that have a variety of roles, both essential and non-essential, in metabolism and in biotic and abiotic interactions, as well as commercial applications such as pharmaceuticals, food additives, and chemical feedstocks. Economic viability for commercial applications is commonly not achievable by using natural source organisms or chemical synthesis. Engineered bio-production in suitable heterologous hosts is often required to achieve commercial viability. However, our poor understanding of regulatory mechanisms and other biochemical processes makes obtaining efficient conversion yields from feedstocks challenging. Moreover, production from carbon dioxide via photosynthesis would significantly increase the environmental and potentially the economic credentials of these processes by disintermediating biomass feedstocks. In this paper, we briefly review terpenoid metabolism, outline some recent advances in terpenoid metabolic engineering, and discuss why photosynthetic unicellular organisms—such as algae and cyanobacteria—might be preferred production platforms for the expression of some of the more challenging terpenoid pathways
Interactive Sonification for Structural Biology and Structure-based Drug Design
The visualisation of structural biology data can be quite challenging as the datasets are complex, in particular the intrinsic dynamics/flexibility. Therefore some researchers have looked into the use of sonification for the display of proteins. Combining sonification and visualisation appears to be well fitted to this problem, but at the time of writing there are no plugins available for any of the major molecular visualisation applications.
Therefore we set out to develop a sonification plugin for one of those applications, released as open-source software, in order to facilitate scrutiny and evaluation from as many parties as possible. This paper presents our open source sonification plugin for UCSF Chimera, which we have developed in collaboration with medicinal chemists and structural biologists. We determined two tasks that we deemed were not well represented visually and developed sonifications for them. Furthermore, we extended a general-purpose Chimera tool to map attributes of protein residues to pitch.
We evaluated one of the tasks with eight participants and present the results of this evaluation
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