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Your search keyword '"Roberts, C J"' showing total 963 results
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963 results on '"Roberts, C J"'

1. NASA's astrophysics cross-observatory science support (ACROSS) initiative: enabling time-domain and multimessenger astrophysics.

Author

Humensky, T. B., Roberts, C. J., Barclay, T., Caputo, R., Cenko, S. B., Civano, F., Derleth, J., Hedges, C., Hui, M. C., Kennea, J. A., Kocevski, D., Racusin, J., Rani, B., Sambruna, R. M., and Slutsky, J.

Subjects
*WEB portals, *HYPERLINKS, *ASTROPHYSICS, *PILOT projects, *COMPUTER software
Abstract

The Astro2020 Decadal Survey recommended an investment in Time-Domain and Multimessenger Astrophysics (TDAMM) as the top-priority sustaining activity in space for the coming decade. One aspect of NASA's response to this recommendation is a pilot project, the Astrophysics Cross-Observatory Science Support (ACROSS) initiative, designed to provide support to both missions and observers as they pursue TDAMM science. Here, we present our observations of needs in the community and initial plans for ACROSS activities, including services to facilitate and improve cross-mission follow-up planning and execution; a multimessenger web portal with links to existing mission resources, community tools, and information targeted for TDAMM general observers; development of "Smart target-of-opportunity submission page" proof-of-concepts; and ongoing development of a potential TDAMM general observing competitive grant solicitation. As the ACROSS pilot phase begins, we invite discussion of our plans with both missions and observers to better understand their needs and concerns. [ABSTRACT FROM AUTHOR]

Published
2024
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2. The operator product expansion on the lattice

Author

Bietenholz, W., Cundy, N., Göckeler, M., Horsley, R., Perlt, H., Pleiter, D., Rakow, P. E. L., Roberts, C. J., Schierholz, G., Schiller, A., and Zanotti, J. M.

Subjects
High Energy Physics - Lattice
Abstract

We investigate the Operator Product Expansion (OPE) on the lattice by directly measuring the product (where J is the vector current) and comparing it with the expectation values of bilinear operators. This will determine the Wilson coefficients in the OPE from lattice data, and so give an alternative to the conventional methods of renormalising lattice structure function calculations. It could also give us access to higher twist quantities such as the longitudinal structure function F_L = F_2 - 2 x F_1. We use overlap fermions because of their improved chiral properties, which reduces the number of possible operator mixing coefficients., Comment: 7 pages, 4 postscript figures. Contribution to Lattice 2007, Regensburg

Published
2007

3. Nucleon Structure from Quenched Overlap Fermions

Author

Galletly, D., Gürtler, M., Horsley, R., Koller, K., Linke, V., Rakow, P. E. L., Roberts, C. J., Schierholz, G., and Streuer, T.

Subjects
High Energy Physics - Lattice
Abstract

We compute the lowest moments of the nucleon's structure functions using quenched overlap fermions at two different lattice spacings. The renormalisation is done nonperturbatively in the RI'-MOM-scheme., Comment: Talk presented at Lattice2005 (Matrix Elements), Dublin, July 25-30, 2005; 6 pages, 6 figures, uses PoS.cls; to appear in Proceedings of Science

Published
2005

4. Non-perturbative renormalisation for overlap fermions

Author

Gürtler, M., Horsley, R., Rakow, P. E. L., Roberts, C. J., Schierholz, G., and Streuer, T.

Subjects
High Energy Physics - Lattice
Abstract

Using non-perturbative techniques we have found the renormalisation factor, Z, in the RI-MOM scheme for quark bilinear operators in quenched QCD. We worked with overlap fermions using the Luescher-Weisz gauge action. Our calculation was performed at beta=8.45 at a lattice spacing of 1/a=2.1 GeV using a value of rho=1.4. Our results show good agreement between the vector and the axial vector in the zero mass limit. This shows that overlap fermions have good chiral properties. To attempt to improve the discretisation errors in our results we subtracted the O(a^2) terms in one-loop lattice perturbation theory from the Monte Carlo Green functions. In particular we paid attention to the operators for the observable . We found a value for the renormalisation constants Z^msbar_(v_2b) and Z^msbar_(v_2a) just less than 1.9 at mu=1/a=2.1 GeV., Comment: 6 pages, 3 figures, uses PoS style, poster presented at Lattice 2005 (Chiral Fermions), to be published in Proceedings of Science

Published
2005

9. Rationing Health Care

Author

Roe, Marion, MacKay, Kate, Roberts, C. J., Crosby, D. L., Field, Stephen, Giles, Adrian, Wilkins, L. T., Wilkins, A. J., Burdon, Justin, Packham, C. J., Edwards, Rhiannon Tudor, Burns-Cox, C. J., Smith, Iain, Plomer, Aurora, and Robinson, Ray

Published
1996

22. The impact of an emotionally expressive writing intervention on eating pathology in female students

Author

Kupeli, N., Schmidt, U. H., Campbell, I. C., Chilcot, J., Roberts, C. J., and Troop, N. A.

Subjects
stress, BMI, lcsh:Psychology, lcsh:R, lcsh:BF1-990, Expressive writing, lcsh:Medicine, disordered eating
Abstract

ntroduction: Previous research demonstrating emotional influences on eating and weight suggest that emotionally expressive writing may have a significant impact on reducing risk of eating pathology. This study examined the effects of writing about Intensely Positive Experiences on weight and disordered eating during a naturalistic stressor.Method: Seventy-one female students completed an expressive or a control writing task before a period of exams. Both groups were compared on BMI (kg/m2) and the Eating Disorder Examination – Questionnaire (EDE-Q) before the writing task and at 8-week follow-up. A number of secondary analyses were also examined (to identify potential mediators) including measures of attachment, social rank, self-criticism and self-reassurance, stress and mood.Results: There was a significant effect of intervention on changes in the subscales of the EDE-Q (p = .03). Specifically, expressive writers significantly reduced their dietary restraint while those in the control group did not. There was no significant effect of the intervention on changes in BMI or the other subscales of the EDE-Q (Eating, Weight and Shape Concern). There was also no effect of writing on any of the potential mediators in the secondary analyses.Discussion: Emotionally expressive writing may reduce the risk of dietary restraint in women but these findings should be accepted with caution. It is a simple and light touch intervention that has the potential to be widely applied. However, it remains for future research to replicate these results and to identify the mechanisms of action.

Published
2018
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48. Chemical vapor deposition growth of carbon nanotubes on Si substrates using Fe catalyst: What happens at the nanotube/Fe/Si interface.

Author

Chakraborty, Amit K., Jacobs, J., Anderson, C., Roberts, C. J., and Hunt, Michael R. C.

Subjects
NANOTUBES, CHEMICAL vapor deposition, IRON catalysts, ATOMIC force microscopy, X-ray photoelectron spectroscopy, ETHYLENE, ACETYLENE, METHANE, EVAPORATION (Chemistry)
Abstract

Direct growth of carbon nanotubes (CNTs) on silicon is of great importance for their potential exploitation in the semiconductor industry. In this article we investigate the chemical vapor deposition growth of CNTs on Si substrates from ethylene precursor using an iron catalyst. We observe that CNTs are produced only at temperatures between 830 and 980 °C, and within this narrow temperature window CNT yield initially increases with temperature to reach a maximum around 900 °C and then declines. While the requirement of a minimum temperature to initiate CNT growth can be understood by considering the minimum energy necessary to activate the catalyst particles, characterization of the as-grown CNTs by atomic force microscopy and x-ray photoelectron spectroscopy reveals that a loss of catalyst is responsible for the observed decline in CNT yield above 900 °C. However, unlike some previous reports suggesting surface silicide formation as the mechanism for catalyst loss, we find that either subsurface diffusion or evaporation is the mechanism for the loss of catalyst material in the current study. [ABSTRACT FROM AUTHOR]

Published
2006
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50. Antenatal Diagnosis Of Spina Bifida

Author

Harris, R., Jennison, R. F., Barson, A. J., Addison, G. M., Evans, K. T., Hibbard, Bryan, Laurence, K. M., Lowe, C. R., and Roberts, C. J.

Published
1975

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