284 research outputs found
The on-top pair-correlation density in the homogeneous electron liquid
The ladder theory, in which the Bethe-Goldstone equation for the effective
potential between two scattering particles plays a central role, is well known
for its satisfactory description of the short-range correlations in the
homogeneous electron liquid. By solving exactly the Bethe-Goldstone equation in
the limit of large transfer momentum between two scattering particles, we
obtain accurate results for the on-top pair-correlation density , in both
three dimensions and two dimensions. Furthermore, we prove, in general, the
ladder theory satisfies the cusp condition for the pair-correlation density
at zero distance .Comment: 8 pages, 4 figure
Transport on Directed Percolation Clusters
We study random lattice networks consisting of resistor like and diode like
bonds. For investigating the transport properties of these random resistor
diode networks we introduce a field theoretic Hamiltonian amenable to
renormalization group analysis. We focus on the average two-port resistance at
the transition from the nonpercolating to the directed percolating phase and
calculate the corresponding resistance exponent to two-loop order.
Moreover, we determine the backbone dimension of directed percolation
clusters to two-loop order. We obtain a scaling relation for that is in
agreement with well known scaling arguments.Comment: 4 page
Directed Surfaces in Disordered Media
The critical exponents for a class of one-dimensional models of interface
depinning in disordered media can be calculated through a mapping onto directed
percolation (DP). In higher dimensions these models give rise to directed
surfaces, which do not belong to the directed percolation universality class.
We formulate a scaling theory of directed surfaces, and calculate critical
exponents numerically, using a cellular automaton that locates the directed
surfaces without making reference to the dynamics of the underlying interface
growth models.Comment: 4 pages, REVTEX, 2 Postscript figures avaliable from [email protected]
Coating quality as affected by core particle segregation in fluidized bed processing
[EN] Fluidized bed coating is an important technique in the food powder industry, where often particles of a wide size distribution are dealt with. In this paper, glass beads of different particle size distribution were coated with sodium caseinate in a top-spray fluid bed unit. Positron Emission Particle Tracking (PEPT) was used to visualize and quantify the particle motion in the fluidized bed. Confocal Laser Scanning Microscopy combined with image analysis were used to investigate the effect of core particle size and its distribution on the thickness and quality of the coating. Particle size significantly affected the thickness and quality of the coating, due to differences in the corresponding fluidization patterns, as corroborated by PEPT observations. As the particle size distribution becomes narrower, segregation is less likely to occur. This results in a thicker coating which is, however, less uniform compared to when cores of a wider particle size distribution are spray coated. (C) 2012 Elsevier Ltd. All rights reserved.The authors wish to thank the financial support received from the Fund for Scientific Research-Flanders (Belgium) (F.W.O.-Vlaanderen), as well as from the Programa de Apoyo a la Investigacion y Desarrollo from the Universitat Politecnica de Valencia.Atarés Huerta, LM.; Depypere, F.; Pieters, J.; Dewettinck, K. (2012). Coating quality as affected by core particle segregation in fluidized bed processing. Journal of Food Engineering. 113(3):415-421. doi:10.1016/j.jfoodeng.2012.06.012S415421113
Analysis of fibrinogen A alpha-fusion proteins. Mutants which inhibit thrombin equivalently are not equally good substrates.
We have examined the interaction of thrombin with fibrinogen A alpha chain residues 7-16. Using genetically engineered constructions, we have synthesized in Escherichia coli a fibrinogen A alpha 1-50 fusion protein and seven mutant proteins with single amino acid substitutions. These are: Asp7----Ala, Phe8----Tyr, Glu11----Ala, Gly12----Val, Gly13----Val, Gly14----Val, and Arg16----Leu. Competitive immunoassay of cell lysates showed that all the mutations but one, Arg16----Leu, altered the structure of the protein such that cross-reactivity with the A alpha-specific monoclonal antibody, Y18, was significantly reduced. The fusion proteins were purified and analyzed as thrombin inhibitors and substrates. All the fusion proteins are competitive inhibitors of the amidolytic hydrolysis of Spectrozyme TH, a thrombin-specific chromogenic substrate, with inhibition constants corresponding to that for fibrinogen. We conclude that these 7 amino acid substitutions do not alter thrombin binding to the fusion proteins. The fusion proteins were tested as substrates by monitoring thrombin-dependent peptide release. The natural sequence and three mutants, Asp7----Ala, Glu11----Ala, and Gly14----Val, are good substrates. The other mutants are either poor substrates or are not cleaved by thrombin within A alpha 1-50. These results indicate that residues between Asp7 and Arg16 are critical to efficient peptide hydrolysis, whereas residues outside this region are critical to thrombin binding
The script concordance test in radiation oncology: validation study of a new tool to assess clinical reasoning
<p>Abstract</p> <p>Background</p> <p>The Script Concordance test (SCT) is a reliable and valid tool to evaluate clinical reasoning in complex situations where experts' opinions may be divided. Scores reflect the degree of concordance between the performance of examinees and that of a reference panel of experienced physicians. The purpose of this study is to demonstrate SCT's usefulness in radiation oncology.</p> <p>Methods</p> <p>A 90 items radiation oncology SCT was administered to 155 participants. Three levels of experience were tested: medical students (n = 70), radiation oncology residents (n = 38) and radiation oncologists (n = 47). Statistical tests were performed to assess reliability and to document validity.</p> <p>Results</p> <p>After item optimization, the test comprised 30 cases and 70 questions. Cronbach alpha was 0.90. Mean scores were 51.62 (± 8.19) for students, 71.20 (± 9.45) for residents and 76.67 (± 6.14) for radiation oncologists. The difference between the three groups was statistically significant when compared by the Kruskall-Wallis test (p < 0.001).</p> <p>Conclusion</p> <p>The SCT is reliable and useful to discriminate among participants according to their level of experience in radiation oncology. It appears as a useful tool to document the progression of reasoning during residency training.</p
Investigation of ligand interactions with human RXRα by hydrogen/deuterium exchange and mass spectrometry
Stakeholders, collaboration, food, and wine: The case of Jumillaâs Gastronomic Days
An emerging literature on gastronomic events highlights the growing interest among academics, event organisers and development agencies in identifying potential or actual outcomes from gastronomic events. Partly in response to such interest, this study seeks to contribute to the literature on events management, studying the contribution of various stakeholders involved in the âGastronomic Daysâ of Jumilla, Spain. Semi-structured, face-to-face, in-depth interviews were conducted with the managers and owners of four participating businesses to the event. The data collection was complemented through on-site visits, observations, and interviews with eight other local businesses. The findings underline the significance of collaboration among these participants to grow and sustain the event, as well as voluntary efforts by event âstakeholders.â Importantly, a common objective was identified in the form of enhancing the image of the local products, and overall that of the region, to âconvertâ residents, and also outside consumers and tourists to Jumillaâs products. These findings have significant implications for Jumillaâs community. In particular, the importance and efforts of a regionâs food stakeholders in contributing to adding value and improving the local food culture emerge as useful aspects, with potential benefits for local food growers, hospitality and tourism sectors, and residents
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