117,292 research outputs found
Computing the effective action with the functional renormalization group
No full textThe “exact” or “functional” renormalization group equation describes the renormalization group flow of the effective average action Γ k. The ordinary effective action Γ 0 can be obtained by integrating the flow equation from an ultraviolet scale k= Λ down to k= 0. We give several examples of such calculations at one-loop, both in renormalizable and in effective field theories. We reproduce the four-point scattering amplitude in the case of a real scalar field theory with quartic potential and in the case of the pion chiral Lagrangian. In the case of gauge theories, we reproduce the vacuum polarization of QED and of Yang–Mills theory. We also compute the two-point functions for scalars and gravitons in the effective field theory of scalar fields minimally coupled to gravity. © 2016, The Author(s)
Computing the effective action with the functional renormalization group
No full textThe "exact" or "functional" renormalization group equation describes the renormalization group flow of the effective average action Gamma(k). The ordinary effective action Gamma(0) can be obtained by integrating the flow equation from an ultraviolet scale k = Lambda downto k = 0. We give several examples of such calculations at one-loop, both in renormalizable and in effective field theories. We reproduce the four-point scattering amplitude in the case of a real scalar field theory with quartic potential and in the case of the pion chiral Lagrangian. In the case of gauge theories, we reproduce the vacuum polarization of QED and of Yang-Mills theory. We also compute the two-point functions for scalars and gravitons in the effective field theory of scalar fields minimally coupled to gravity
Kidney preservation in pigs using celsior, a new organ preservation solution
No full textImpact Factor:0.44
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Effect of antiadhesive agents on peritoneal carcinomatosis in an experimental model
No full textBackground: Auto-crosslinked polysaccharide hyaluronan-based solution (Hyalobarrier®-gel) prevents postoperative adhesions. However, its effect on tumour growth is still unknown. The aim of the present study was therefore to investigate the impact on survival of intra-abdominally administered Hyalobarrier®-gel, native hyaluronan (HA) and hyaluronan/carboxymethylcellulose (HA/CMC), after intraperitoneal tumour implantation. Methods: After receiving an intraperitoneal inoculum of the human HT29 colorectal cell line, 615 athymic nude mice were assigned randomly to five groups: groups 1 and 2 received Hyalobarrier®-gel 20 mg/ml (n = 124) and 40 mg/ml (n = 126) respectively; groups 3 and 4 received HA (n = 120) and HA/CMC film (SeprafilmTM) (n = 123) respectively. The survival of each treated group was compared with that of group 5, the control, which had no treatment (n = 122). Results: As 34 of the 615 mice were not eligible, 581 animals were considered for the analysis. At 120 days, 136 animals (23.4 per cent) were still alive. At autopsy there was macroscopic absence of tumour in 75 cases (12.9 per cent). No statistically significant differences were found between the treatment and the control groups with respect to postoperative death and absence of tumour implantation. There was no difference in survival rate between the control group and groups treated with Hyalobarrier®-gel, HA or HA/CMC. Conclusion: Hyalobarrier®-gel, HA and HA/CMC had no negative impact on the survival rate in mice that received an intraperitoneal implantation of HT29 colorectal human tumour cells
Square Dancing with the Stars to Enhance Dynamic Hirschman Linkages?
No full textIn this Presidential Address, the author takes the reader on a reconnaissance of his life and time as a regional scientist. He points out scenery he found scintillating along the way, hoping that some may pick up the banner and chew on a few of the ideas for a while. He suggests a revisit to Albert O. Hirschman’s notion of key sectors and more empirical analysis related to Marcus Berliant’s and Masahisa Fujita’s notion of knowledge creation and transfer.Presidential Address, San Antonio, Texas, March 29, 2014 (53rd Meetings of the Southern Regional Science Association
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Letter from unknown writer to Jesse L. Boyce
No full textLetter to Jesse L. Boyce from unknown author (possibly Jack) about the investigation into the powder magazine located in the Grand Canyon. Some personal news is included in the letter such as the writer's marriage to the daughter of C.A. Taylor, former Supervisor of Cochise County
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
One-Loop Effective Action in Quantum Gravitation
No full textWe present the formalism of computing one-loop effective action for Quantum Gravitation using non-local heat kernel methods. We found agreement with previous old results. In main part of my presentation I considered the system of E-H gravitation and scalar fields. We were able to derive non-local quantum effective action up to the second order in heat kernel generalized curvatures. By going to flat spacetime expressions for gravitational form factors are possible to construct and compare with the results from effective field theory for gravity
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