4,673 research outputs found
A new information theoretical measure of global and local spatial association
In this paper a new measure of spatial association, the S statistics, is developed. The proposed measure is based on information theory by defining a spatially weighted information measure (entropy measure) that takes the spatial configuration into account. The proposed S-statistics has an intuitive interpretation, and furthermore fulfills properties that are expected from an entropy measure. Moreover, the S statistics is a global measure of spatial association that can be decomposed into Local Indicators of Spatial Association (LISA). This new measure is tested using a dataset of employment in the culture sector that was attached to the wards over Stockholm County and later compared with the results from current global and local measures of spatial association. It is shown that the proposed S statistics share many properties with Moran's I and Getis-Ord Gi statistics. The local Si statistics showed significant spatial association similar to the Gi statistic, but has the advantage of being possible to aggregate to a global measure of spatial association. The statistics can also be extended to bivariate distributions. It is shown that the commonly used Bayesian empirical approach can be interpreted as a Kullback-Leibler divergence measure. An advantage of S-statistics is that this measure select only the most robust clusters, eliminating the contribution of smaller ones composed by few observations and that may inflate the global measure.Global and local measure of spatial association, LISA, S-statistics, Gi statistics, Moran's I, Kullback-Leibler divergence,
3D finite element simulations of reinforced concrete elements exposed to fire
Fire could dramatically reduce strength of reinforced concrete elements and it is considered one of the major threats for the structural safety of buildings: structural members may even collapse due to intensity and duration of fire. In this study, 3D finite element simulations of reinforced concrete elements under fire loading are presented. A quasi static one-way-coupled thermo-mechanical analysis is carried out, in which a heat transfer simulation is
conducted first and then internal forces are computed. A phe- nomenological constitutive model based on damage-plasticity is used for concrete at high temperature. Transient creep strains are included in the model for elevated temperature. Extended Leon model is used for yield function and isotropic damage is assumed. Numer- ical results are compared with experimental data found in the literature, showing good agreement
A Participatory Approach to Assess the Effectiveness of Responses to Cope With Flood Risk
This work illustrates the preliminary findings of a participatory research process aimed at identifying responses for sustainable water management in a climate change perspective, in two river basins in Europe and Asia. The paper describes the methodology implemented through local workshops, aimed at eliciting and evaluating possible responses to flood risk. Participatory workshops allowed for the identification of four categories of possible responses and a set of nine evaluation criteria, three for each of the three pillars of sustainable development. The main outcome of such activities consists in the ranking of broad response categories instrumental to the objective of the Brahmatwinn research project, i.e. the identification of Integrated Water Resource Management Strategies (IWRMS) based upon the issues and preferences elicited from local experts. The mDSS tool was used to facilitate transparent and robust management of the information collected through Multi-Criteria Decision Analysis (MCDA) and communication of the outputs.Participatory Process, Climate Change, Flood Risk, Decision Support System, Multi Criteria Analysis, MCA, Eliciting Responses, Evaluating Responses, Integrated Water Resources Management, IWRM, Mulino Decision Support System, mDSS
Assessing the Impact of Modernization on Fertility: The Case of Mozambique
Mozambique is one of the poorest countries in the world. It also has one of the world's highest birth rates. Until recently there has been virtually no way to study Mozambique's high fertility because of the civil war. This paper uses a very recent survey of Mozambican women from 1997. The objective of this paper is to assess the impact of modernization on fertility in Mozambique, using as a background the "supply-demand theory" presented by Easterlin and Crimmins (1985). The first part of this paper describes the indicators of modernization for Mozambique by using maps, and indicates eventual correlations. The second part deals with the estimation of equations for demand for children, the supply of children and the use of contraception. The third part shows how the modernization variables visualized in the first part of the paper influence all these equations. The results show that the country has one of the highest demands for children in the world, but also one of the largest supply of children, followed by high infant and child mortality. In many provinces, the regulation costs are still high. Those who deliberately use contraceptives already have many children. Among the modernization variables, education is the factor that most affects supply, demand and also regulation costs in Mozambique
Multivariate small sample tests for two-way designs with applications to industrial statistics
In this paper, we present a novel nonparametric approach for multivariate analysis of two-way crossed factorial design based on NonParametric Combination applied to Synchronized Permutation tests. This nonparametric hypothesis testing procedure not only allows to overcome the shortcomings of MANOVA test like violation of assumptions such as multivariate normality or covariance homogeneity, but, in an extensive simulation study, reveals to be a powerful instrument both in case of small sample size and many response variables. We contextualize its application in the field of industrial experiments and we assume a linear additive model for the data set analysis. Indeed, the linear additive model interpretation well adapts to the industrial production environment because of the way control of production machineries is implemented. The case of small sample size reflects the frequent needs of practitioners in the industrial environment where there are constraints or limited resources for the experimental design. Furthermore, an increase in rejection rate can be observed under alternative hypothesis when the number of response variables increases with fixed number of observed units. This could lead to a strategical benefit considering that in many real problems it could be easier to collect more information on a single experimental unit than adding a new unit to the experimental design. An application to industrial thermoforming processes is useful to illustrate and highlight the benefits of the adoption of the herein presented nonparametric approach
MPM simulations of the impact of fast landslides on retaining dams
Possible protection systems against flow-like landslides are earth dams built to stop or deviate the flow. The evaluation of impact forces on the structures is still based on oversimplified empirical approaches, which may lead to a very conservative design, with high costs and environmental impact. Numerical methods able to capture the essential features of the phenomenon can offer a valuable tool to support the design of protection measures. This paper shows the potentialities of the Material Point Method (MPM) in this field. A dry granular flow, modelled with the Mohr-Coulomb model is considered. The landslide is placed in front of the barrier with a prescribed velocity and the impact forces on the slanted face is monitored with time
Study of the effect of the drainage conditions on the cone penetration with the Material Point Method
Adhesive Contact Algorithm for MPM and its Application to the Simulation of Cone Penetration in Clay
The Pathophysiology and Treatment of Hypertension in Patients With Cushing's Syndrome
When hypertension, a pathology that is frequently found in the general population, presents in a young patient, secondary causes such as Cushing's syndrome (CS), a rare disease characterized by long-term elevated cortisol levels, should be considered. Present in ~80% of CS patients independently of their age and sex, hypertension is one of the pathology's most prevalent, alarming features. Its severity is principally associated with the duration and intensity of elevated cortisol levels. Prompt diagnosis and rapid initiation of treatment are important for reducing/delaying the consequences of hypercortisolism. Glucocorticoid excess leads to hypertension via a variety of mechanisms including mineralocorticoid mimetic activity, alterations in peripheral and renovascular resistance, and vascular remodeling. As hypertension in CS patients is caused by cortisol excess, treating the underlying pathology generally contributes to reducing blood pressure (BP) levels, although hypertension tends to persist in approximately 30% of cured patients. Surgical removal of the pituitary tumor remains the first-line treatment for both adrenocorticotropin hormone (ACTH) dependent and independent forms of the syndrome. In light of the fact that surgery is not always successful in curing the underlying disease, it is essential that other treatments be considered and prescribed as needed. This article discusses the mechanisms involved in the pathogenesis of CS and the pros and the cons of the various antihypertensive agents that are presently available to treat these patients
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