79 resultados para Pure points of a measure
Resumo:
The European Natura 2000 project attempts to balance conservation and exploitation by permitting activities that do not affect the conservation status of designated sites. Given the scale of Natura 2000, guidelines are needed to facilitate the drafting of simple site management plans. This need is particularly acute for traditional harvesting methods for which there is usually strong local opposition to the imposition of controls. These issues were examined in Strangford Lough, a special area of conservation where cockles have traditionally been harvested by hand-raking. Raking was found not to affect the ability of cockles to rebury. There were significant reductions in Zostera biomass when raking was carried out within eelgrass beds (a 90% reduction in biomass available to winter migrant birds from summer raking). Traditional harvesting methods could therefore be accepted in Strangford as long as Zostera beds are avoided. A relatively low intensity of harvesting activity in Strangford Lough probably reflects low cockle densities (average 91.8 m(-2)), with the most economically valuable individuals at some distance from points of access to the shore. An economically feasible management plan could sanction traditional harvesting and result in the implementation of more resource-intensive management only if increases in cockle stocks and market prices stimulate large increases in harvesting activity.
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Feminist theorists have long critiqued the hierarchical gender division inherent in Western societies, with the inequalities resulting from this divide being widely decried and some progress made in reducing these. Despite increased efforts to theorise trans identification in recent times, gender is still largely understood, both culturally and theoretically, as adhering to the dualism of male/female. I argue within this paper that consideration of the narratives of transpeople and their partners could expand our conceptualisation of gender and offers possible points of resistance from which to challenge the gender binary, thereby destabilising hegemonic discourses of gender. As such I explore the narratives of transpeople and their partners in relation to the construction and reconstruction of gendered subjectivities. Transpeople’s intimate partnerships, considered here due to the critique of gender norms often evident within them, are examined through the theoretical lens of Foucault’s notion of governmentality. This paper offers an example of how governmentality can be a useful tool in the effort to understand gender regulation, not least for those apparently on the margins of ‘normality’.
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We define a category of quasi-coherent sheaves of topological spaces on projective toric varieties and prove a splitting result for its algebraic K-theory, generalising earlier results for projective spaces. The splitting is expressed in terms of the number of interior lattice points of dilations of a polytope associated to the variety. The proof uses combinatorial and geometrical results on polytopal complexes. The same methods also give an elementary explicit calculation of the cohomology groups of a projective toric variety over any commutative ring.
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Logistic regression and Gaussian mixture model (GMM) classifiers have been trained to estimate the probability of acute myocardial infarction (AMI) in patients based upon the concentrations of a panel of cardiac markers. The panel consists of two new markers, fatty acid binding protein (FABP) and glycogen phosphorylase BB (GPBB), in addition to the traditional cardiac troponin I (cTnI), creatine kinase MB (CKMB) and myoglobin. The effect of using principal component analysis (PCA) and Fisher discriminant analysis (FDA) to preprocess the marker concentrations was also investigated. The need for classifiers to give an accurate estimate of the probability of AMI is argued and three categories of performance measure are described, namely discriminatory ability, sharpness, and reliability. Numerical performance measures for each category are given and applied. The optimum classifier, based solely upon the samples take on admission, was the logistic regression classifier using FDA preprocessing. This gave an accuracy of 0.85 (95% confidence interval: 0.78-0.91) and a normalised Brier score of 0.89. When samples at both admission and a further time, 1-6 h later, were included, the performance increased significantly, showing that logistic regression classifiers can indeed use the information from the five cardiac markers to accurately and reliably estimate the probability AMI. © Springer-Verlag London Limited 2008.
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Let H be a two-dimensional complex Hilbert space and P(3H) the space of 3-homogeneous polynomials on H. We give a characterization of the extreme points of its unit ball, P(3H), from which we deduce that the unit sphere of P(3H) is the disjoint union of the sets of its extreme and smooth points. We also show that an extreme point of P(3H) remains extreme as considered as an element of L(3H). Finally we make a few remarks about the geometry of the unit ball of the predual of P(3H) and give a characterization of its smooth points.
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Following automation of lighthouses around the coastline of Ireland, reports of accelerated deterioration of interior granite stonework have increased significantly with an associated deterioration in the historic structure and rise in related maintenance costs. Decay of granite stone- work primarily occurs through granular disintegration with the effective grusification of granite surfaces. A decay gradient exists within the towers whereby the condition of granite in the lower levels is much worse than elsewhere. The lower tower levels are also regions with highest rela- tive humidity values and greatest salt concentrations. Data indicate that post-automation decay may have been trig- gered by a change in micro-environmental conditions within the towers associated with increased episodes of condensation on stone surfaces. This in turn appears to have facilitated deposition and accumulation of hygro- scopic salts (e.g. NaCl) giving rise to widespread evidence of deliquescence in the lower tower levels. Evidence indicates that the main factors contributing to accelerated deterioration of interior granite stonework are changes in micro-environmental conditions, salt weathering, chemical weathering through the corrosive effect of strongly alkaline conditions on alumino-silicate minerals within the granite and finally, the mica-rich characteristics of the granite itself which increases its structural and chemical susceptibility to subaerial weathering processes by creating points of weakness within the granite. This case study demonstrates how seemingly minor changes in micro-environmental conditions can unintentionally trigger the rapid and extensive deterioration of a previously stable rock type and threaten the long-term future of nationally iconic opera- tional historic structures.
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Since the 'completion' of Histoire(s) du cinema (1988-1998), Jean-Luc Godard's work has become increasingly mosaic-like in its forms and configurations, and markedly elegiac in its ruminations on history, cinema, art, and thought. While his associative aesthetic and citational method –including his choice of ‘actors’, and the fragmentariness of his ‘soundtracks’ – can combine to create a distinctive cinematic event, the films themselves refuse to cohere around a unifying concern, or yield to a thematic schema. Not surprisingly, Film Socialisme does not offer us the illusion of narrative or structural integrity anymore than it contributes to the quotidian rhetoric of political and moral argument. It is, however, a political film in the sense that it alters something more fundamental than opinions and points of view. It transforms a way of seeing and understanding reality and history, fiction and documentary, images, and images of images. If anything, it belongs to that dissident or ‘dissensual’ category of artwork capable of ‘emancipating the spectator’ by disturbing what Jacques Rancière terms ‘the distribution of the sensible’ in that it generates gaps, openings, and spaces, poses questions, invites associations without positing a fixed position, imposing an interpretation, or allowing itself to invest in the illusion of expressive objectivity and the stability of meaning. The myriad citations and fragments that comprise the film are never intended to culminate into anything cohesive, never mind conclusive. In one sense, they have no source and no context beyond their moment in the film itself, and what we make of that moment. This article studies the degree to which Godard allows these images and sounds to combine and collide, associate and dissolve in this film, arguing that Film Socialisme is both an important intervention in the history of contemporary cinema, and necessary point of reference in any serious discussion of the relations between that cinema and political reality.
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In this paper we define the structural information content of graphs as their corresponding graph entropy. This definition is based on local vertex functionals obtained by calculating-spheres via the algorithm of Dijkstra. We prove that the graph entropy and, hence, the local vertex functionals can be computed with polynomial time complexity enabling the application of our measure for large graphs. In this paper we present numerical results for the graph entropy of chemical graphs and discuss resulting properties. (C) 2007 Elsevier Ltd. All rights reserved.
Resumo:
Measuring the structural similarity of graphs is a challenging and outstanding problem. Most of the classical approaches of the so-called exact graph matching methods are based on graph or subgraph isomorphic relations of the underlying graphs. In contrast to these methods in this paper we introduce a novel approach to measure the structural similarity of directed and undirected graphs that is mainly based on margins of feature vectors representing graphs. We introduce novel graph similarity and dissimilarity measures, provide some properties and analyze their algorithmic complexity. We find that the computational complexity of our measures is polynomial in the graph size and, hence, significantly better than classical methods from, e.g. exact graph matching which are NP-complete. Numerically, we provide some examples of our measure and compare the results with the well-known graph edit distance. (c) 2006 Elsevier Inc. All rights reserved.
Resumo:
Computing has recently reached an inflection point with the introduction of multicore processors. On-chip thread-level parallelism is doubling approximately every other year. Concurrency lends itself naturally to allowing a program to trade performance for power savings by regulating the number of active cores; however, in several domains, users are unwilling to sacrifice performance to save power. We present a prediction model for identifying energy-efficient operating points of concurrency in well-tuned multithreaded scientific applications and a runtime system that uses live program analysis to optimize applications dynamically. We describe a dynamic phase-aware performance prediction model that combines multivariate regression techniques with runtime analysis of data collected from hardware event counters to locate optimal operating points of concurrency. Using our model, we develop a prediction-driven phase-aware runtime optimization scheme that throttles concurrency so that power consumption can be reduced and performance can be set at the knee of the scalability curve of each program phase. The use of prediction reduces the overhead of searching the optimization space while achieving near-optimal performance and power savings. A thorough evaluation of our approach shows a reduction in power consumption of 10.8 percent, simultaneous with an improvement in performance of 17.9 percent, resulting in energy savings of 26.7 percent.
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Ethanol adsorption-desorption isotherms on well-organized mesoporous silica and titania films with hexagonal pores structure were studied by ellipsometric porosimetry. The mesopore volume Was calculated from the change of the effective refractive index at the end points of the isotherm. An improved Derjaguin-Broekhoff-de Boer (IDBdB) model for cylindrical pores is proposed for the determination of the pore size. In this model, the disjoining pressure isotherms were obtained by measuring the thickness of the ethanol film on a non-porous film with the same chemical composition. This approach eliminates uncertainties related to the application of the statistical film thickness determined via t-plots in previous versions of the DBdB model. The deviation in the surface tension of ethanol in the mesopores from that of a flat interface was described by the Tolman parameter in the Gibbs-Tolman-Koening-Buff equation. A positive value of the Tolman parameter of 0.2 nm was found from the fitting of the desorption branch of the isotherms to the experimental data obtained by Low Angle X-ray Diffraction (LA-XRD) and Transmission Electron Microscopy (TEM) measurements in the range of pore diameters between 2.1 and 8.3 nm. (C) 2009 Elsevier Inc. All rights reserved.
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Background: Mandatory fortification of grain products with folic acid was introduced recently in the United States, a policy expected to result in a mean additional intake of 100 mu g/d. One way of predicting the effectiveness of this measure is to determine the effect of removing a similar amount of folic acid as fortified food from the diets of young women who had been electively exposed to chronic fortification.
Objective: The objective was to examine the effect on folate status of foods fortified with low amounts of folic acid.
Design: We investigated the changes in dietary intakes and in red blood cell and serum concentrations of folate in response to removing folic acid-fortified foods for 12 wk from the diets of women who reportedly consumed such foods at least once weekly (consumers).
Results: Consumers (n = 21) had higher total folate intakes (P = 0.002) and red blood cell folate concentrations (P = 0.023) than nonconsumers (women who consumed folic acid-fortified foods less than once weekly; n = 30). Of greater interest, a 12-wk intervention involving the exclusion of these foods resulted in a decrease in folate intake of 78 +/- 56 mu g/d (P < 0.001), which was reflected in a significant reduction in red blood cell folate concentrations (P < 0.05).
Conclusions: Cessation of eating folic acid-fortified foods resulted in removing 78 mu g folic acid/d from the diet. Over 12 wk this resulted in a lowering of red blood cell folate concentrations by 111 nmol/L (49 mu g/L). This magnitude of change in folate status in women can be anticipated as a result of the new US fortification legislation and is predicted to have a significant, although not optimal, effect in preventing neural tube defects.
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Diffuse contaminants can make their way into rivers via a number of different pathways, including overland flow, interflow, and shallow and deep groundwater. Identification of the key pathway(s) delivering contaminants to a receptor is important for implementing effective water management strategies. The ‘Pathways Project’, funded by the Irish Environmental Protection Agency, is developing a catchment management tool that will enable practitioners to identify the critical source areas for diffuse contaminants, and the key pathways of interest in assessing contaminant problems on a catchment and sub-catchment scale.
One of the aims of the project is to quantify the flow and contaminant loadings being delivered to the stream via each of the main pathways. Chemical separation of stream event hydrographs is being used to supplement more traditional physical hydrograph separation methods. Distinct, stable chemical signatures are derived for each of the pathway end members, and the proportion of flow from each during a rainfall event can be determined using a simple mass balance approach.
Event sampling was carried out in a test catchment underlain by poorly permeable soils and bedrock, which is predominantly used for grazing with a number of one-off rural residential houses. Results show that artificial field drainage, which includes subterranean land drains and collector drains around the perimeters of the 1 to 10 ha fields, plays an important role in the delivery of flow and nutrients to the streams in these types of hydrogeological settings.
Nitrate infiltrates with recharge and is delivered to the stream primarily via the artificial drains and the shallow groundwater pathway. Longitudinal stream profiles show that the nitrate load input is relatively uniform over the 8 km length of the stream at high flows, suggesting widespread diffuse contaminant input. In contrast, phosphorus is adsorbed in the clay-rich soil and is transported mainly via the overland flow pathway and the artificial drains. Longitudinal stream profiles for phosphorus suggest a pattern of more discrete points of phosphorus inputs, which may be related to point sources of contamination.
These techniques have application elsewhere within a toolkit of methods for determining the key pathways delivering contaminants to surface water receptors.
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Greylag geese (Anser anser) in the Guadalquivir Marshes (southwestern Spain) can be exposed to sources of inorganic pollution such as heavy metals and arsenic from mining activities or Pb shot used for hunting. We have sampled 270 fecal excreta in different areas of the marshes in 2001 to 2002 to evaluate the exposure to Pb, Zn, Cu, Mn, and As and to determine its relationship with soil ingestion and with the excretion of porphyrins and biliverdin as biomarkers. These effects and the histopathology of liver, kidney, and pancreas were also studied in 50 geese shot in 2002 to 2004. None of the geese had ingested Pb shot in the gizzard. This contrasts with earlier samplings before the ban of Pb shot for waterfowl hunting in 2001 and the removal of Pb shot in points of the Doñana National Park (Spain) in 1999 to 2000. The highest exposure through direct soil ingestion to Pb and other studied elements was observed in samples from Entremuros, the area of the Doñana Natural Park affected by the Aznalcóllar mine spill in 1998. Birds from Entremuros also more frequently showed mononuclear infiltrates in liver and kidney than birds from the unaffected areas, although other more specific lesions of Pb or Zn poisoning were not observed. The excretion of coproporphyrins, especially of the isomer I, was positively related to the fecal As concentration, and the ratio of coproporphyrin III/I was positively related to fecal Pb concentration. Biliary protoporphyrin IX concentration was also slightly related to hepatic Pb concentration. This study reflects biological effects on terrestrial animals by the mining pollution in Doñana that can be monitored with the simple noninvasive sampling of feces.