1,445 research outputs found

    Half and quarter BPS operators in N = 4 super Yang-Mills

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    PhD ThesisIn this thesis we perform calculations on the CFT side of the duality between N = 4 supersymmetric Yang-Mills theory and type IIB string theory on AdS5 x S5. The results are used to study quantum gravity on AdS. Chapters 3 and 4 explore the structure and combinatorics of the quarter BPS sector with gauge groups U(N), SO(N) and Sp(N) in the planar free field limit. For U(N), we identify the multi-traces with a word monoid, with aperiodic single traces corresponding to Lyndon words. For SO(N) and Sp(N) we generalise Lyndon words using minimally periodic conditions. We present the quarter-BPS generating function for SO(N)/Sp(N) gauge groups. Chapter 5 examines the permutation algebras behind operator construction in the free field theory with SO(N) and Sp(N) gauge groups. There is a rich group independent structure, including formulae for correlators expressed purely in terms of permutations. We introduce Schur and restricted Schur bases for the baryonic sector of the SO(N) theory, derive covariant bases for the quarter-BPS sectors of SO(N) and Sp(N) theories, and calculate their correlators. Chapter 6 studies the projection of the half-BPS sector from the U(N) theory to the SO(N)/Sp(N) theory, dual to an orientifold projection of S5 to RP5. This is characterised by a plethystic refinement of Littlewood-Richardson coefficients, expressible in terms of the combinatorics of domino diagrams. A second expression for the projection is derived in terms of a product of SO(N)/Sp(N) giant graviton states. Chapter 7 looks at the quarter-BPS sector of the U(N) theory at weak coupling. Multi-symmetric functions allow systematic study of the finite N properties, involving combinatorics of set partitions. We construct a quarter-BPS, finite N-compatible, U(2) covariant, orthogonal basis, labelled by a U(N) Young diagram and a multiplicity, for which we derive precise counting results. These are interpreted as quarter-BPS deformations of the half-BPS giant graviton states

    An Empirical Analysis of the Economic Impact of Federal Terrorism Reinsurance

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    This paper examines the role of the federal government in the market for terrorism reinsurance. We investigate the stock price response of affected industries to a sequence of thirteen events culminating in the enactment of the Terrorism Risk Insurance Act (TRIA) of 2002. In the industries most likely to be affected by TRIA banking, construction, insurance, real estate investment trusts, transportation, and public utilities the stock price effect was primarily negative. The Act was at best value-neutral for property-casualty insurers because it eliminated the option not to offer terrorism insurance. The negative response of the other industries may be attributable to the Act's impeding more efficient private market solutions, failing to address nuclear, chemical, and biological hazards, and reducing market expectations of federal assistance following future terrorist attacks.

    Team strategic philosophy: requiem for the infinite game

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    Deliberate accountability has arrived in the medical arena, producing an age of reward for measured performance, and belief in publicizing metrics to ensure clarity, with winning defined as hitting targets, whereby staff are incentivised by arbitrary objectives. Finite game theory declares that players are known, rules are fixed, and the objective agreed, but infinite game theory asserts that players are both known and unknown, rules are changeable, and the objective is to perpetuate the game; these standards are clearly at odds and risk real world chaos in global universal medical education and clinical outcomes and functioning. Five principles are necessary to lead an infinite game: first, a fair basis, such that sacrifices for its advancement are promoted; second, a trusting blame-free team culture and environment; third, competitors viewed as worthy rivals, rather than adversaries, promoting healthy competition; fourth, existential flexibility when faced with credible evidence; and finally, transformational leadership; including infinite game theory into healthcare planning may be difficult, but the potential rewards are surely worth the existential fight

    Status of nearshore finfish stocks in south-western Western Australia: Part 1: Australian herring

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    The status of the popular nearshore finfish resource in the West Coast Bioregion (WCB) of Western Australia (WA) was largely unknown prior to this study. Previously, declining catches of several nearshore species had highlighted the risk to their sustainability and the need for greater certainty about their status. Recently, the risk further increased due to management changes in the WCB aimed at reducing the catch of demersal scalefish, which are likely to result in a shift in targeting towards nearshore species. This increase in fishing pressure on nearshore species will be on top of any increase due to the continuing human population growth in the WCB

    Altmetric versus bibliometric perspective regarding publication impact and force

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    Background Bibliometric and Altmetric analyses highlight key publications, which have been considered to be the most influential in their field. The hypothesis was that highly cited articles would correlate positively with levels of evidence and Altmetric scores (AS) and rank. Methods Surgery as a search term was entered into Thomson Reuter’s Web of Science database to identify all English-language full articles. The 100 most cited articles were analysed by topic, journal, author, year, institution, and AS. Results By bibliometric criteria, eligible articles numbered 286,122 and the median (range) citation number was 574 (446–5746). The most cited article (Dindo et al.) classified surgical complications by severity score (5746 citations). Annals of Surgery published most articles and received most citations (26,457). The country and year with most publications were the USA (n = 50) and 1999 (n = 11). By Altmetric criteria, the article with the highest AS was by Bigelow et al. (AS = 53, hypothermia’s role in cardiac surgery); Annals of Surgery published most articles, and the country and year with most publications were USA (n = 4) and 2007 (n = 3). Level-1-evidence articles numbered 13, but no correlation was found between evidence level and citation number (SCC 0.094, p = 0.352) or AS (SCC = 0.149, p = 0.244). Median AS was 0 (0–53), and in articles published after the year 2000, AS was associated with citation number (r = 0.461, p = 0.001) and citation rate index (r = 0.455, p = 0.002). AS was not associated with journal impact factor (r = 0.160, p = 0.118). Conclusion Bibliometric and Altmetric analyses provide important but different perspectives regarding article impact, which are unrelated to evidence level

    The Grizzly, November 6, 2014

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    Dr. Peter Small Appointed as Interim Dean • Berman Receives Large Grant • Graduates Granted Campus Housing • Campus Safety Handles Thefts • Senate Changes Organization • Learning to Embrace American Foods • Watson Fellowship Nominees Announced • Myrin Undergoes Renovations • Dr. Jennifer Fleeger Writes Book on Mismatched Female Voices in Film • Opinion: The Francis Effect Alters Public Perception of Roman Catholic Church; How Proactive is Rape Prevention Nail Polish? • Men\u27s Swim Hoping to Make a Splash • Pinning Down Success • Field Hockey to Host Centennial Playoffshttps://digitalcommons.ursinus.edu/grizzlynews/1915/thumbnail.jp

    Enantioselective Intramolecular C-H Amination Catalyzed by Engineered Cytochrome P450 Enzymes In Vitro and In Vivo

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    Nitrogen activation: Though P450 enzymes are masters of oxygen activation and insertion into C-H bonds, their ability to use nitrogen for the same purpose has so far not been explored. Engineered variants of cytochrome P450_(BM3) have now been found to catalyze intramolecular C-H aminations in azide substrates. Mutations to two highly conserved residues significantly increased this activity

    Molecular analyses reveal consistent food web structure with elevation in rainforest Drosophila – parasitoid communities

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    The analysis of interaction networks across spatial environmental gradients is a powerful approach to investigate the responses of communities to global change. Using a combination of DNA metabarcoding and traditional molecular methods we built bipartite Drosophila-parasitoid food webs from six Australian rainforest sites across gradients spanning 850 m in elevation and 5° Celsius in mean temperature. Our cost-effective hierarchical approach to network reconstruction separated the determination of host frequencies from the detection and quantification of interactions. The food webs comprised 5-9 host and 5-11 parasitoid species at each site, and showed a lower incidence of parasitism at high elevation. Despite considerable turnover in the relative abundance of host Drosophila species, and contrary to some previous results, we did not detect significant changes to fundamental metrics of network structure including nestedness and specialisation with elevation. Advances in community ecology depend on data from a combination of methodological approaches. It is therefore especially valuable to develop model study systems for sets of closely-interacting species that are diverse enough to be representative, yet still amenable to field and laboratory experiments

    Molecular analyses reveal consistent food web structure with elevation in rainforest Drosophila – parasitoid communities

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    The analysis of interaction networks across spatial environmental gradients is a powerful approach to investigate the responses of communities to global change. Using a combination of DNA metabarcoding and traditional molecular methods we built bipartite Drosophila – parasitoid food webs from six Australian rainforest sites across gradients spanning 850 m in elevation and 5°C in mean temperature. Our cost-effective hierarchical approach to network reconstruction separated the determination of host frequencies from the detection and quantification of interactions. The food webs comprised 5–9 host and 5–11 parasitoid species at each site, and showed a lower incidence of parasitism at high elevation. Despite considerable turnover in the relative abundance of host Drosophila species, and contrary to some previous results, we did not detect significant changes to fundamental metrics of network structure including nestedness and specialisation with elevation. Advances in community ecology depend on data from a combination of methodological approaches. It is therefore especially valuable to develop model study systems for sets of closely-interacting species that are diverse enough to be representative, yet still amenable to field and laboratory experiments

    The Grizzly, October 23, 2014

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    Website Launching • Homecoming Kicking Off This Weekend • Board to Discuss New President • Good Neighbors Debuting This Week • Grizzly Gala Returning • American Class Style Can be Surprising • Throop Researches Medieval Europe • U-Innovate Competition Returns • Don\u27t Forget About Small Majors • Opinion: The Problem With Capital Punishment; Extraterrestrial Existence: Reason to Believe? • Football Team Preparing for Homecoming • Serving Up Success • Field Hockey Dashes to 11-2 Starthttps://digitalcommons.ursinus.edu/grizzlynews/1913/thumbnail.jp
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