Algebraic Curvature Tensors of Einstein and Weakly Einstein Model Spaces

This research investigates the restrictions on the symmetric bilinear form with associated algebraic curvature tensor R in Einstein and Weakly Einstein model spaces. We show that if a model space is Einstein and has a positive definite inner product, then: if the scalar curvature is non-negative, the model space has constant sectional curvature, and if the scalar curvature is negative, the matrix associated to the symmetric bilinear form can have at most two eigenvalues

When is Artification?

How do people do or make things that come to be seen as works of art? In other words, when is there artification? The answer to this question is simultaneously symbolic, material, and contextual. It has to do with meanings, objects, interaction, and institutions. We seek to define not what art is nor how it should be considered, but how and under what circumstances it comes about by way of methodical observation and inquiry in a variety of fields. Circus acrobats, breakdancers, fashion designers, chefs, graffiti artists, printers, photographers, and jazz musicians are some of the examples we explore. This pragmatic and empirical perspective enables us to present a typology of forms of artification and examine its sources as well as the questions of de-artification and obstacles to artification

When is Artification?

How do people do or make things that come to be seen as works of art? In other words, when is there artification? The answer to this question is simultaneously symbolic, material, and contextual. It has to do with meanings, objects, interaction, and institutions. We seek to define not what art is nor how it should be considered, but how and under what circumstances it comes about by way of methodical observation and inquiry in a variety of fields. Circus acrobats, break-dancers, fashion designers, chefs, graffiti artists, printers, photographers, and jazz musicians are some of the examples we explore. This pragmatic and empirical perspective enables us to present a typology of forms of artification and examine its sources as well as the questions of de-artification and obstacles to artification

Que é artificação?

Há um aumento constante na produção de arte na sociedade e na pesquisa sobre arte e cultura dentro das ciências sociais. Conseqüentemente, parece apropriado propor a artificação como um campo novo para a Sociologia da Arte e da mudança social e cultural. A artificação é a transformação da não-arte em arte. Isto consiste em um processo social complexo da transfiguração das pessoas, das coisas e das práticas. A artificação não somente tem a ver com mudança simbólica, deslocamento de hierarquias e legitimidade, mas, implica, também modificações muito concretas nos traços físicos e nas maneiras das pessoas, nas formas de cooperação e organização, nos bens e nos artefatos que são usados, etc. Esses processos redefinem os limites entre a arte e a não-arte, e reconstróem mundos sociais novos. Neste artigo, são utilizados como exemplos de artificação o hip-hop, a fonografia, a gravura, a água-forte, o trabalho industrial e a arte primitiva

Quando há Artificação?

 Como as pessoas fazem ou criam coisas que passam a ser vistas como obras de arte? Em outras palavras, quando há artificação? A resposta a essa pergunta é, ao mesmo tempo, simbólica, material e contextual. Tem a ver com significados, objetos, interação e instituições. Não procuramos definir o que é arte ou como ela deve ser considerada, mas como e sob quais circunstâncias ela ocorre por meio de observação metódica e pesquisa em diversos campos. Acrobatas de circos, dançarinos de breakdance, estilistas, chefes de cozinha, grafiteiros, tipógrafos, fotógrafos e músicos de jazz são alguns dos exemplos que exploramos. Essa perspectiva pragmática e empírica permite que possamos apresentar uma tipologia das formas de artificação e examinar suas fontes, bem como as questões de des-artificação e os obstáculos à artificação

Automorphisms of the k-Curve Graph

Given a natural number k and an orientable surface S of finite type, define the k-curve graph to be the graph with vertices corresponding to isotopy classes of essential simple closed curves on S and with edges corresponding to pairs of such curves admitting representatives that intersect at most k times. We prove that the automorphism group of the k-curve graph of a surface S is isomorphic to the extended mapping class group for all k sufficiently small with respect to the Euler characteristic of S. We prove the same result for the so-called systolic complex, a variant of the curve graph whose complete subgraphs encode the intersection patterns for any collection of systoles with respect to a hyperbolic metric. This resolves a conjecture of Schmutz Schaller.Comment: 22 pages, 11 figures, 1 tabl

Soluble adhesion molecules as markers for sepsis and the potential pathophysiological discrepancy in neonates, children and adults

Sepsis is a severe and life-threatening systemic inflammatory response to infection that affects all populations and age groups. The pathophysiology of sepsis is associated with aberrant interaction between leukocytes and the vascular endothelium. As inflammation progresses, the adhesion molecules that mediate these interactions become shed from cell surfaces and accumulate in the blood as soluble isoforms that are being explored as potential prognostic disease biomarkers. We critically review the studies that have tested the predictive value of soluble adhesion molecules in sepsis pathophysiology with emphasis on age, as well as the underlying mechanisms and potential roles for inflammatory shedding. Five soluble adhesion molecules are associated with sepsis, specifically, E-selectin, L-selectin and P-selectin, intercellular adhesion molecule-1 and vascular cell adhesion molecule-1. While increased levels of these soluble adhesion molecules generally correlate well with the presence of sepsis, their degree of elevation is still poorly predictive of sepsis severity scores, outcome and mortality. Separate analyses of neonates, children and adults demonstrate significant age-dependent discrepancies in both basal and septic levels of circulating soluble adhesion molecules. Additionally, a range of both clinical and experimental studies suggests protective roles for adhesion molecule shedding that raise important questions about whether these should positively or negatively correlate with mortality. In conclusion, while predictive properties of soluble adhesion molecules have been researched intensively, their levels are still poorly predictive of sepsis outcome and mortality. We propose two novel directions for improving clinical utility of soluble adhesion molecules: the combined simultaneous analysis of levels of adhesion molecules and their sheddases; and taking age-related discrepancies into account. Further attention to these issues may provide better understanding of sepsis pathophysiology and increase the usefulness of soluble adhesion molecules as diagnostic and predictive biomarkers

Logic programs as specifications in the inductive verification of logic programs

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Anomaly Poles as Common Signatures of Chiral and Conformal Anomalies

One feature of the chiral anomaly, analyzed in a perturbative framework, is the appearance of massless poles which account for it. They are identified by a spectral analysis of the anomaly graph and are usually interpreted as being of an infrared origin. Recent investigations show that their presence is not just confined in the infrared, but that they appear in the effective action under the most general kinematical conditions, even if they decouple in the infrared. Further studies reveal that they are responsible for the non-unitary behaviour of these theories in the ultraviolet (UV) region. We extend this analysis to the case of the conformal anomaly, showing that the effective action describing the interaction of gauge fields with gravity is characterized by anomaly poles that give the entire anomaly and are decoupled in the infrared (IR), in complete analogy with the chiral case. This complements a related analysis by Giannotti and Mottola on the trace anomaly in gravity, in which an anomaly pole has been identified in the corresponding correlator using dispersion theory in the IR. Our extension is based on an exact computation of the off-shell correlation function involving an energy-momentum tensor and two vector currents (the gauge-gauge-graviton vertex) which is responsible for the appearance of the anomaly.Comment: 13 pages, 4 figures revised final version, to appear on Phys. Lett.