2,440 research outputs found

    High angular resolution observation of the Sunyaev-Zel'dovich effect in the massive z=0.83 cluster ClJ0152-1357

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    X-ray observations of galaxy clusters at high redshift (z>0.5) indicate that they are more morphologically complex and less virialized than those at low-redshift. We present the first subarcmin resolution at 18 GHz observations of the Sunyaev-Zel'dovich (SZ) effect for ClJ0152-1357 using the Australia Telescope Compact Array. ClJ0152-1357 is a massive cluster at redshift z=0.83 and has a complex structure including several merging subclumps which have been studied at optical, X-ray, and radio wavelengths. Our high-resolution observations indicate a clear displacement of the maximum SZ effect from the peak of X-ray emission for the most massive sub-clump. This result shows that the cluster gas within the cluster substructures is not virialised in ClJ0152-1357 and we suggest that it is still recovering from a recent merger event. A similar offset of the SZ effect has been recently seen in the `bullet cluster' by Malu et al. This non-equilibrium situation implies that high resolution observations are necessary to investigate galaxy cluster evolution, and to extract cosmological constraints from a comparison of the SZ effect and X-ray signals.Comment: 5 pages, 4 figures, submitted to ApJ

    Application of ERTS-1 imagery to the harvest model of the US Menhaden fishery

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    Preliminary results of an experiment to demonstrate the utility of ERTS-1 imagery for providing significant information to the harvest model of the menhaden industry are reported. Fisheries and related environmental data were obtained discontinuously throughout the 1973 menhaden (a surface schooling, coastal species) fishing season in Mississippi Sound. The unexpected complexity of the physical environment in Mississippi Sound precluded simplistic analysis of fish/environment relationships. Preliminary indications are that an association does exist between fish availability and differences in water transparency (turbidity) within the Sound. A clearer relationship is developing between major turbid features, imaged by ERTS-1 and location of successful fishing attempts. On all occasions where relatively cloudfree ERTS-1 overflight days coincided with fishery activity, overlays of catch location of ERTS-1 images show an association of school position with interfaces between imaged turbid features. Analysis is currently underway to determine persistence of such associations in an attempt to define minimum satellite return time necessary to maintain continuity of associations

    Exploring faculty experiences with e-books: a focus group

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    Abstract: Purpose – The purpose of this paper is to describe how, in the spring of 2007, Arizona State University Libraries held a focus group of selected faculty to discover their perceptions and use of electronic books (e-books) in their research and teaching. Design/methodology/approach – The services of the Institute of Social Sciences Research were employed to recruit and moderate the focus group. Major themes explored were: use of e-books as textbooks; use of e-books for personal research; comparison between e-books and print; disciplinary differences in perceptions of e-books; and motivators for future use. Findings – Overall, the focus group revealed that faculty had generally unsatisfactory experiences in using e-books in their research and teaching owing to the unreliability of access, lack of manipulability, and the steep learning curve of the various interfaces. However, most faculty agreed that e-books would be a very viable and useful alternative if these issues were resolved. Research limitations/implications – The focus group consisted of only six faculty members and hence is not representative of faculty as a whole. A larger survey of a more diverse faculty population would greatly serve to clarify and expand upon the findings. Practical implications – The implications for academic libraries include providing better outreach and training to faculty about the e-book platforms offered, provide better course support, and advocate to e-book vendors to consider faculty's teaching and research needs in their product development. Originality/value – This is believed to be the first published study of faculty opinions and use of e-books utilizing focus group methodology and offers detailed information that would be useful for academic libraries and e-book vendors for evidence-based decisions

    Separating the BL Lac and Cluster X-ray Emissions in Abell 689 with Chandra

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    We present the results of a Chandra observation of the galaxy cluster Abell 689 (z=0.279). Abell 689 is one of the most luminous clusters detected in the ROSAT All Sky Survey (RASS), but was flagged as possibly including significant point source contamination. The small PSF of the Chandra telescope allows us to confirm this and separate the point source from the extended cluster X-ray emission. For the cluster we determine a bolometric luminosity of L_{bol}=(3.3+/-0.3)x10^{44} erg s-1 and a temperature of kT=5.1^{+2.2}_{-1.3} keV when including a physically motivated background model. We compare our measured luminosity for A689 to that quoted in the Rosat All Sky Survey (RASS) and find L_{0.1-2.4,keV}=2.8x10^{44} erg s-1, a value \sim10 times lower than the ROSAT measurement. Our analysis of the point source shows evidence for significant pileup, with a pile-up fraction of ~60%. SDSS spectra and HST images lead us to the conclusion that the point source within Abell 689 is a BL Lac object. Using radio and optical observations from the VLA and HST archives, we determine {\alpha}_{ro}=0.50, {\alpha}_{ox}=0.77 and {\alpha}_{rx}=0.58 for the BL Lac, which would classify it as being of 'High-energy peak BL Lac' (HBL) type. Spectra extracted of A689 show a hard X-ray excess at energies above 6 keV that we interpret as inverse Compton emission from aged electrons that may have been transported into the cluster from the BL Lac.Comment: 11 pages, 15 figures, MNRAS in pres

    Training and Pruning Tart Cherries

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    Training and pruning tart cherry trees is critical to the production of quality fruit. The benefits of proper pruning and training are abundant yields of high-quality fruit. Pruning and training early in the life of the tree is critical to establish the desired tree form, and to make future pruning and maintenance less complicated. It is important to note that not every tree will be picture-perfect, as trees are unique in their shape and form, however, following proper pruning principles will give imperfect trees the best opportunity to produce fruit. The main objectives of pruning are to 1) develop good structure and strong limbs, 2) control the height of the tree, allowing for easier harvest, 3) maintain a new supply of limbs that are of optimal fruit-bearing age and placement, and 4) remove any damaged, diseased, or non-productive growth

    Chandra Measurements of a Complete Sample of X-ray Luminous Galaxy Clusters: The Luminosity-Mass Relation

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    We present the results of work involving a statistically complete sample of 34 galaxy clusters, in the redshift range 0.15≤\lez≤\le0.3 observed with ChandraChandra. We investigate the luminosity-mass (LMLM) relation for the cluster sample, with the masses obtained via a full hydrostatic mass analysis. We utilise a method to fully account for selection biases when modeling the LMLM relation, and find that the LMLM relation is significantly different than the relation modelled when not account for selection effects. We find that the luminosity of our clusters is 2.2±\pm0.4 times higher (when accounting for selection effects) than the average for a given mass, its mass is 30% lower than the population average for a given luminosity. Equivalently, using the LMLM relation measured from this sample without correcting for selection biases would lead to the underestimation by 40% of the average mass of a cluster with a given luminosity. Comparing the hydrostatic masses to mass estimates determined from the YXY_{X} parameter, we find that they are entirely consistent, irrespective of the dynamical state of the cluster.Comment: 31 pages, 43 figures, accepted for publication in MNRA

    PET/MRI of Hepatic 90Y Microsphere Deposition Determines Individual Tumor Response.

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    PurposeThe purpose of our study is to determine if there is a relationship between dose deposition measured by PET/MRI and individual lesion response to yttrium-90 ((90)Y) microsphere radioembolization.Materials and methods26 patients undergoing lobar treatment with (90)Y microspheres underwent PET/MRI within 66 h of treatment and had follow-up imaging available. Adequate visualization of tumor was available in 24 patients, and contours were drawn on simultaneously acquired PET/MRI data. Dose volume histograms (DVHs) were extracted from dose maps, which were generated using a voxelized dose kernel. Similar contours to capture dimensional and volumetric change of tumors were drawn on follow-up imaging. Response was analyzed using both RECIST and volumetric RECIST (vRECIST) criteria.ResultsA total of 8 hepatocellular carcinoma (HCC), 4 neuroendocrine tumor (NET), 9 colorectal metastases (CRC) patients, and 3 patients with other metastatic disease met inclusion criteria. Average dose was useful in predicting response between responders and non-responders for all lesion types and for CRC lesions alone using both response criteria (p < 0.05). D70 (minimum dose to 70 % of volume) was also useful in predicting response when using vRECIST. No significant trend was seen in the other tumor types. For CRC lesions, an average dose of 29.8 Gy offered 76.9 % sensitivity and 75.9 % specificity for response.ConclusionsPET/MRI of (90)Y microsphere distribution showed significantly higher DVH values for responders than non-responders in patients with CRC. DVH analysis of (90)Y microsphere distribution following treatment may be an important predictor of response and could be used to guide future adaptive therapy trials

    Tart Cherries in the Garden

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    Tart cherry (Prunus cerasus), also known as sour cherry or pie cherry, is an excellent addition to home orchards that is often overlooked. Trees can easily be tucked into landscapes and can provide an abundant supply of cherries for freezing, drying, canning, juicing, and preserves. Several cultivars are available for selection and may be purchased on semi-dwarfing rootstocks to help trees maintain a manageable size. Trees generally grow well in Utah climates and conditions and are relatively easy to maintain and prune. Potential insect and disease problems are minimal and include Powdery Mildew and Western Cherry Fruit Fly. These potential problems can be well managed using integrated pest management techniques
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