Flight crew interface aspects of forward-looking airborne windshear detection systems

The goal of this research effort was to conduct analyses and research which could provide guidelines for design of the crew interface of an integrated windshear system. Addressed were HF issues, crew/system requirements, candidate display formats, alerting criteria, and crew procedures. A survey identified five flight management issues as top priority: missed alert acceptability; avoidance distance needed; false alert acceptability; nuisance rate acceptability; and crew procedures. Results of a simulation study indicated that the warning time for a look-ahead alert needs to be between 11 and 36 seconds (target of 23 seconds) before the reactive system triggers in order to be effective. Pilots considered the standard go-around maneuver most appropriate for look-ahead alerts, and the escape maneuvers used did not require lateral turns. Prototype display formats were reviewed or developed for alerting the crew; providing guidance to avoid or escape windshear; and status displays to provide windshear situational awareness. The three alerting levels now in use were considered appropriate, with a fourth (time-critical) level as a possible addition, although many reviewers felt only two levels of alerting were needed. Another survey gathered expert opinion on what crew procedures and alerting criteria should be used for look-ahead, or integrated, windshear systems, with a wide diversity of opinion in these areas

Crop Fertilization on Texas Alluvial Soils.

4 p

Factores preditivos da formação de aderências pleurais e sucesso da pleurodese nos doentes com derrame pleural

RESUMO: As aderências pleurais podem complicar a realização da pleurodese por toracoscopia. Os autores decidiram realizar este estudo para determinar os factores preditivos da formação e extensão das aderências pleurais e do sucesso da pleurodese em doentes submetidos a toracoscopia e talcagem.Os doentes submetidos a toracoscopia no Georgetown University Medical Center entre Agosto de 1995 e Março de 2002 foram estudados retrospectivamente. Os autores registaram o n.° de toracenteses, a duração do derrame, a malignidade, a origem doença subjacente, a existência de irradiação torácica, a presença e extensão das aderências pleurais e o sucesso da pleurodese. Foram estudados 89 doentes que tinham todos estes dados registados.Numa análise global, só os derrames pleurais que tinham uma duração superior a 5 meses têm um valor preditivo na formação das aderências (p=0,037) e extensão das mesmas (p=0,038). No grupo dos derrames pleurais malignos com uma duração superior a 5 meses este aspecto também tem um valor preditivo na formação (p=0,020) e extensão (p=0,037) das aderências. No grupo particular dos derrames pleurais secundários ao cancro da mama, a duração superior a 5 meses também tem um valor preditivo na formação (p=0,008) e extensão (p=0,011) das aderências pleurais.A regressão estatística determinou que a duração dos derrames superior a 5 meses é neste estudo o único factor preditivo na formação das aderências pleurais e que não existem factores preditivos do sucesso da pleurodese. A duração do derrame pleural, independentemente da sua etiologia, está associada à formação de espessas aderências pleurais, particularmente naqueles que tem uma duração superior a 5 meses. COMENTÁRIO: Nos EUA, 1,5 a 2 milhões de doentes por ano tem um derrame pleural. Cerca de 1/3 são secundários a insuficiência cardíaca e 20% estão relacionados com pneumonias bacterianas. Quinze a 40% são derrames pleurais malignos e, destes, cerca de 30% a 40% são secundários ao cancro do pulmão e 25% ao cancro da mama.A rentabilidade da citologia do líquido pleural (50% a70%) e das biópsias pleurais (39% a 75%) não é satisfatória. Estes factos levam a considerar a toracoscopia o exame indicado nos derrames pleurais sem diagnóstico, pois permite a visualização directa das superfícies pleurais e a realização das biópsias directamente. A toracoscopia permite também realizar a insuflação de talco e a pleurodese.A presença de aderências pleurais dificulta a realização da toracoscopia. A efectividade da pleurodese é diminuída porque as aderências cobrem parcialmente a pleura visceral e a pleura parietal, dificultando a sua aderência.A referência na literatura que a produção de citocinas inflamatórias, a subsequente formação de fibrina e a eventual formação de aderências pleurais, estão relacionadas com o número de toracenteses realizadas previamente à toracoscopia e que poderão afectar o êxito da pleurodese, é um dos aspectos que levou os autores a realizarem este estudo.Os resultados contrariaram em parte estes conceitos. Os autores constataram que a formação das aderências e a sua extensão estavam em parte relacionadas com a gravidade da doença subjacente e com a duração do derrame pleural. Não conseguiram estabelecer relação entre número de toracenteses e a formação de aderências assim como com o êxito ou não da pleurodese.Estatiscamente, só conseguiram estabelecer como factor preditivo da formação e da extensão de aderências a duração do derrame pleural quando superior a 5meses. Em relação aos factores preditivos do sucesso da pleurodese, neste estudo os autores não conseguiram estabelecer; contudo, não foram analisados os valores do pH do líquido pleural que é considerado em algumas séries como factor preditivo (pH <7,20 é um sinal de insucesso da pleurodese).A existência de aderências pleurais não é um factor directo de insucesso da pleurodese, mas como dificulta a realização da toracoscopia e da eventual talcagem é sempre um aspecto a considerar no êxito da toracoscopia/talcagem. Palavras-chave: Derrame pleural, aderências pleurais, toracoscopia, talcage

The Principle of Symmetric Criticality in General Relativity

We consider a version of Palais' Principle of Symmetric Criticality (PSC) that is applicable to the Lie symmetry reduction of Lagrangian field theories. PSC asserts that, given a group action, for any group-invariant Lagrangian the equations obtained by restriction of Euler-Lagrange equations to group-invariant fields are equivalent to the Euler-Lagrange equations of a canonically defined, symmetry-reduced Lagrangian. We investigate the validity of PSC for local gravitational theories built from a metric. It is shown that there are two independent conditions which must be satisfied for PSC to be valid. One of these conditions, obtained previously in the context of transverse symmetry group actions, provides a generalization of the well-known unimodularity condition that arises in spatially homogeneous cosmological models. The other condition seems to be new. The conditions that determine the validity of PSC are equivalent to pointwise conditions on the group action alone. These results are illustrated with a variety of examples from general relativity. It is straightforward to generalize all of our results to any relativistic field theory.Comment: 46 pages, Plain TeX, references added in revised versio

Asymptotic conservation laws in field theory

A new, general, field theoretic approach to the derivation of asymptotic conservation laws is presented. In this approach asymptotic conservation laws are constructed directly from the field equations according to a universal prescription which does not rely upon the existence of Noether identities or any Lagrangian or Hamiltonian formalisms. The resulting general expressions of the conservation laws enjoy important invariance properties and synthesize all known asymptotic conservation laws, such as the ADM energy in general relativity.Comment: 13 pages, AMS-TeX, amsppt.sty, revised to give a better exposition (we hope), and to correct some typesetting error

Multistate Estimates of Survival and Movement in Relation to Colony Size in the Sociable Weaver

We estimated survival and movement probabilities in relation to breeding-colony size in the sociable weaver (Philetairus socius) by using multistate statistical methods, in which survival and movement to time t + 1 is conditional on an individual’s colony size at time t. The sociable weaver is a colonial, cooperatively breeding species that builds a massive communal nest, with colony size ranging from fewer than 20 to more than 500 individuals in some areas. We conducted an 8-year capture/mark/re-capture study of sociable weavers near Kimberley, South Africa. By comparing the fit of different multistate models to our data, we found evidence that annual survival probability of adults was lower in small colonies (less than 30 individuals) and medium-sized colonies (30–60 individuals) than in large colonies (more than 60 individuals). First-year survival of birds banded as juveniles also increased with natal colony size. Statistically, however, these effects were weak, and models without an effect of colony size were equally well supported by our data. Movement probabilities illustrated that individuals seldom moved between colonies of different size classes, and showed a preference to use colonies of size classes similar to what they had occupied the preceding year, even when changing colony sites between years. The potential survival differences among birds in different colonies, if real, translated into differences of 39–45% in average lifespan. First-year survival is probably enhanced through antipredator advantages of being in larger groups during the fledgling period. Adult survival in larger groups may be increased by thermal advantages of a large nest during cold winter weather. The fidelity of weavers to a particular colony-size class between years may reflect phenotypic specialization for certain group sizes

Information flows and topic modeling in corporate governance

Purpose – Multiple disciplines such as finance, management and economics have contributed to governance research over time. However, the full intellectual structure of the governance “field” including the exchange of knowledge across disciplines and the large variety of governance topics remains to be uncovered. To appreciate the breadth of corporate governance research, it is necessary to understand the disciplinary sources from which the research stems. This manuscript focuses on the interdisciplinary underpinnings of corporate governance research. Design/methodology/approach – This paper employs bibliometric analysis to trace the evolution of corporate governance using articles included in the ISI Web of Science database between 1990 and 2015. Journals included in these categories encompass a full range of business disciplines and provide evidence of the multi-disciplinary nature of corporate governance. It also uncovers the topics treated by disciplines under the governance umbrella using a machine learning method called latent Dirichtlet allocation (LDA). Findings – Corporate governance research deals with a number of strategy-related topics. Unlike strategy topics that reside in a single discipline, corporate governance crosses disciplinary boundaries and includes contributions from accounting, finance, economics, law and management. Our analysis shows that over 80% of corporate governance articles come from outside the field of management. Our LDA solution indicates that the major topics in governance research include corporate governance theory, control of family firms, executive compensation and audit committees. Originality/value – The results illustrate that corporate governance is far more interdisciplinary than previously thought. This is an important insight for corporate governance academics and may lead to collaborative research. More importantly, this research illustrates the usefulness of LDA for investigating interdisciplinary fields. This method is easily transferable to other interdisciplinary fields and it provides a powerful alternative to existing bibliometric methods. We suggest a number of topic areas within library and information science where this method may be applied, including collection development, support for interdisciplinary faculty and basic research into emerging interdisciplinary areas