3,802 research outputs found

    The Molecular Gas Environment around Two Herbig Ae/Be Stars: Resolving the Outflows of LkHa 198 and LkHa 225S

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    Observations of outflows associated with pre-main-sequence stars reveal details about morphology, binarity and evolutionary states of young stellar objects. We present molecular line data from the Berkeley-Illinois-Maryland Association array and Five Colleges Radio Astronomical Observatory toward the regions containing the Herbig Ae/Be stars LkHa 198 and LkHa 225S. Single dish observations of 12CO 1-0, 13CO 1-0, N2H+ 1-0 and CS 2-1 were made over a field of 4.3' x 4.3' for each species. 12CO data from FCRAO were combined with high resolution BIMA array data to achieve a naturally-weighted synthesized beam of 6.75'' x 5.5'' toward LkHa 198 and 5.7'' x 3.95'' toward LkHa 225S, representing resolution improvements of factors of approximately 10 and 5 over existing data. By using uniform weighting, we achieved another factor of two improvement. The outflow around LkHa 198 resolves into at least four outflows, none of which are centered on LkHa 198-IR, but even at our resolution, we cannot exclude the possibility of an outflow associated with this source. In the LkHa 225S region, we find evidence for two outflows associated with LkHa 225S itself and a third outflow is likely driven by this source. Identification of the driving sources is still resolution-limited and is also complicated by the presence of three clouds along the line of sight toward the Cygnus molecular cloud. 13CO is present in the environments of both stars along with cold, dense gas as traced by CS and (in LkHa 225S) N2H+. No 2.6 mm continuum is detected in either region in relatively shallow maps compared to existing continuum observations.Comment: 14 pages, 10 figures (5 color), accepted for publication in Ap

    Marine leptopel, its recovery, measurement and distribution

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    Leptopel, the colloidally or otherwise finely particulate organic and inorganic detritus suspended in natural bodies of water, varies in chemical composition and in relative quantities with reference to depth, latitude and proximity to land. The leptopelic material may be quantitatively recovered by passing the water through an ultrafilter of inert, insoluble adsorptiv.e powder. Apparatus has been designed to so recover such samples in situ at various depths

    Bowel cancer screening and people with intellectual disabilities: working in co-production and establishing principles for good practice initiatives

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    Bowel cancer is the fourth most common cancer in England, and with one in 20 people developing the condition, it is the second highest cause of cancer deaths. If diagnosed early, treatment can be more effective and bowel cancer screening programmes can reduce these mortality figures, yet for people with learning disabilities, the uptake of screening is significantly lower than the rest of the population. Aims To describe the process of co-production when working with a group of people with learning disabilities to explore why they may be reluctant to access bowel cancer screening. Methods A consultation meeting was held with one of the authors, six people with learning disabilities, an advocate and two specialist nurses. A feedback session was organised and a report using clear information was written in conjunction with the participants. Findings Participants discussed what gets in the way of attending for bowel screening and what might help to increase uptake, including awareness, support and clear information. Conclusion Working in co-production proved mutually beneficial as local clinicians also learned how to communicate more effectively with people who have learning disabilities

    Examining the context of instruction to facilitate student success

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    © 2015, © The Author(s) 2015. Identifying effective instructional practices and effective teachers is an important issue in educational research, policy, and practice. However, many schools have resorted to measuring these constructs with student test scores, ignoring the instructional context. In this introductory article to the special issue, we highlight the importance of the instructional context as facilitating of teacher-student relationships, effective instructional practices, and supporting of student success

    PARalyzer: definition of RNA binding sites from PAR-CLIP short-read sequence data

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    Crosslinking and immunoprecipitation (CLIP) protocols have made it possible to identify transcriptome-wide RNA-protein interaction sites. In particular, PAR-CLIP utilizes a photoactivatable nucleoside for more efficient crosslinking. We present an approach, centered on the novel PARalyzer tool, for mapping high-confidence sites from PAR-CLIP deep-sequencing data. We show that PARalyzer delineates sites with a high signal-to-noise ratio. Motif finding identifies the sequence preferences of RNA-binding proteins, as well as seed-matches for highly expressed microRNAs when profiling Argonaute proteins. Our study describes tailored analytical methods and provides guidelines for future efforts to utilize high-throughput sequencing in RNA biology. PARalyzer is available at http://www.genome.duke.edu/labs/ohler/research/PARalyzer/

    Dimensional crossover of a boson gas in multilayers

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    We obtain the thermodynamic properties for a non-interacting Bose gas constrained on multilayers modeled by a periodic Kronig-Penney delta potential in one direction and allowed to be free in the other two directions. We report Bose-Einstein condensation (BEC) critical temperatures, chemical potential, internal energy, specific heat, and entropy for different values of a dimensionless impenetrability P0P\geqslant 0 between layers. The BEC critical temperature TcT_{c} coincides with the ideal gas BEC critical temperature T0T_{0} when P=0P=0 and rapidly goes to zero as PP increases to infinity for any finite interlayer separation. The specific heat CVC_{V} \textit{vs} TT for finite PP and plane separation aa exhibits one minimum and one or two maxima in addition to the BEC, for temperatures larger than TcT_{c} which highlights the effects due to particle confinement. Then we discuss a distinctive dimensional crossover of the system through the specific heat behavior driven by the magnitude of PP. For T<TcT<T_{c} the crossover is revealed by the change in the slope of logCV(T)\log C_{V}(T) and when T>TcT>T_{c}, it is evidenced by a broad minimum in CV(T)C_{V}(T).Comment: Ten pages, nine figure

    enoLOGOS: a versatile web tool for energy normalized sequence logos

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    enoLOGOS is a web-based tool that generates sequence logos from various input sources. Sequence logos have become a popular way to graphically represent DNA and amino acid sequence patterns from a set of aligned sequences. Each position of the alignment is represented by a column of stacked symbols with its total height reflecting the information content in this position. Currently, the available web servers are able to create logo images from a set of aligned sequences, but none of them generates weighted sequence logos directly from energy measurements or other sources. With the advent of high-throughput technologies for estimating the contact energy of different DNA sequences, tools that can create logos directly from binding affinity data are useful to researchers. enoLOGOS generates sequence logos from a variety of input data, including energy measurements, probability matrices, alignment matrices, count matrices and aligned sequences. Furthermore, enoLOGOS can represent the mutual information of different positions of the consensus sequence, a unique feature of this tool. Another web interface for our software, C2H2-enoLOGOS, generates logos for the DNA-binding preferences of the C2H2 zinc-finger transcription factor family members. enoLOGOS and C2H2-enoLOGOS are accessible over the web at

    X-Atlas: An Online Archive of Chandra's Stellar High Energy Transmission Gratings Observations

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    The high-resolution X-ray spectroscopy made possible by the 1999 deployment of the Chandra X-ray Observatory has revolutionized our understanding of stellar X-ray emission. Many puzzles remain, though, particularly regarding the mechanisms of X-ray emission from OB stars. Although numerous individual stars have been observed in high-resolution, realizing the full scientific potential of these observations will necessitate studying the high-resolution Chandra dataset as a whole. To facilitate the rapid comparison and characterization of stellar spectra, we have compiled a uniformly processed database of all stars observed with the Chandra High Energy Transmission Grating (HETG). This database, known as X-Atlas, is accessible through a web interface with searching, data retrieval, and interactive plotting capabilities. For each target, X-Atlas also features predictions of the low-resolution ACIS spectra convolved from the HETG data for comparison with stellar sources in archival ACIS images. Preliminary analyses of the hardness ratios, quantiles, and spectral fits derived from the predicted ACIS spectra reveal systematic differences between the high-mass and low-mass stars in the atlas and offer evidence for at least two distinct classes of high-mass stars. A high degree of X-ray variability is also seen in both high and low-mass stars, including Capella, long thought to exhibit minimal variability. X-Atlas contains over 130 observations of approximately 25 high-mass stars and 40 low-mass stars and will be updated as additional stellar HETG observations become public. The atlas has recently expanded to non-stellar point sources, and Low Energy Transmission Grating (LETG) observations are currently being added as well

    Plasma Cell Ontogeny Defined by Quantitative Changes in Blimp-1 Expression

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    Plasma cells comprise a population of terminally differentiated B cells that are dependent on the transcriptional regulator B lymphocyte–induced maturation protein 1 (Blimp-1) for their development. We have introduced a gfp reporter into the Blimp-1 locus and shown that heterozygous mice express the green fluorescent protein in all antibody-secreting cells (ASCs) in vivo and in vitro. In vitro, these cells display considerable heterogeneity in surface phenotype, immunoglobulin secretion rate, and Blimp-1 expression levels. Importantly, analysis of in vivo ASCs induced by immunization reveals a developmental pathway in which increasing levels of Blimp-1 expression define developmental stages of plasma cell differentiation that have many phenotypic and molecular correlates. Thus, maturation from transient plasmablast to long-lived ASCs in bone marrow is predicated on quantitative increases in Blimp-1 expression
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