Application of bayesian networks to assess water poverty

The conventional approaches to water assessment are inappropriate for describing the increasing complexity of water issues. Instead, an integrated and holistic framework is required to capture the wide range of aspects which are influencing sustainable development of water resources. It is with this in mind that the Water Poverty Index (WPI) was created, as an interdisciplinary policy tool to assess water stress that links physical estimates of water availability with the socio-economic drivers of poverty. In parallel, in light of the investments envisaged for the next decade to reach the sector targets set by the Millennium Development Goals (MDGs), appropriate Decision Support Systems (DSS) are required to inform about the expected impacts to be achieved throughout these interventions. This would provide water managers with adequate information to define strategies that are efficient, effective, and sustainable. The paper explores the use of object oriented Bayesian networks (ooBn) as a valid approach for supporting decision making in water resource planning and management. On the basis of the WPI, a simple ooBn model has been designed and applied to reflect the main issues that determine access to safe water and improved sanitation. A pilot case study is presented for the Turkana district, in Kenya, where the Government has launched a national program to meet sector targets set out in the MDGs. Main impacts of this initiative are evaluated and compared with respect to the present condition. The study concludes that this new approach is able to accommodate local conditions and represent an accurate reflection of the complexities of water issues. Such a tool helps decision-makers to assess the effects of sector-related development policies on the variables of the index, as well as to analyse different future scenarios.Postprint (published version

Robustness of the European power grids under intentional attack

The power grid defines one of the most important technological networks of our times and sustains our complex society. It has evolved for more than a century into an extremely huge and seemingly robust and well understood system. But it becomes extremely fragile as well, when unexpected, usually minimal, failures turn into unknown dynamical behaviours leading, for example, to sudden and massive blackouts. Here we explore the fragility of the European power grid under the effect of selective node removal. A mean field analysis of fragility against attacks is presented together with the observed patterns. Deviations from the theoretical conditions for network percolation (and fragmentation) under attacks are analysed and correlated with non topological reliability measures.Comment: 7 pages, 4 figure

Diversity, competition, extinction: the ecophysics of language change

As early indicated by Charles Darwin, languages behave and change very much like living species. They display high diversity, differentiate in space and time, emerge and disappear. A large body of literature has explored the role of information exchanges and communicative constraints in groups of agents under selective scenarios. These models have been very helpful in providing a rationale on how complex forms of communication emerge under evolutionary pressures. However, other patterns of large-scale organization can be described using mathematical methods ignoring communicative traits. These approaches consider shorter time scales and have been developed by exploiting both theoretical ecology and statistical physics methods. The models are reviewed here and include extinction, invasion, origination, spatial organization, coexistence and diversity as key concepts and are very simple in their defining rules. Such simplicity is used in order to catch the most fundamental laws of organization and those universal ingredients responsible for qualitative traits. The similarities between observed and predicted patterns indicate that an ecological theory of language is emerging, supporting (on a quantitative basis) its ecological nature, although key differences are also present. Here we critically review some recent advances lying and outline their implications and limitations as well as open problems for future research.Comment: 17 Pages. A review on current models from statistical Physics and Theoretical Ecology applied to study language dynamic

Systematic radon survey over active volcanoes

In-soil radon-222 monitoring has been conducted on active volcanoes, in particular on the Arenal, Irazu and Poas volcanoes in Costa Rica and on the Piton de la Fournaise volcano, La Réunion island. Automatic electronic probes buried in soil at one meter depth were used to study the short- and long-term fluctuations of radon related to the external parameters and/or related with the volcanic activity. Three radon stations are in operation on each Costa Rican volcano and a network of 24 stations (with 3 teletransmitted) is operated on the Piton de la Fournaise. Data obtained since 1993 on Costa Rica volcanoes are presented and radon anomalies recorded before the December 8, 1994 eruption of the Irazu volcano are discussed. The Piton de la Fournaise volcano is inactive since mid 1992. We could intensively study the influence of the external parameters on the radon behavior and individuate the type of perturbations induced on short-term measurements. One seismic crisis occurred on November 27, 1996. Radon anomalies appear on most of 50% of the stations 36 hours before the occurrence of the crisis

Free Meixner states

Free Meixner states are a class of functionals on non-commutative polynomials introduced in math.CO/0410482. They are characterized by a resolvent-type form for the generating function of their orthogonal polynomials, by a recursion relation for those polynomials, or by a second-order non-commutative differential equation satisfied by their free cumulant functional. In this paper, we construct an operator model for free Meixner states. By combinatorial methods, we also derive an operator model for their free cumulant functionals. This, in turn, allows us to construct a number of examples. Many of these examples are shown to be trivial, in the sense of being free products of functionals which depend on only a single variable, or rotations of such free products. On the other hand, the multinomial distribution is a free Meixner state and is not a product. Neither is a large class of tracial free Meixner states which are analogous to the simple quadratic exponential families in statistics.Comment: 30 page

Modeling of the Sedative and Airway Obstruction Effects of Propofol in Patients with Parkinson Disease undergoing Stereotactic Surgery

BACKGROUND: Functional stereotactic surgery requires careful titration of sedation since patients with Parkinson disease need to be rapidly awakened for testing. This study reports a population pharmacodynamic model of propofol sedation and airway obstruction in the Parkinson disease population. METHODS: Twenty-one patients with advanced Parkinson disease undergoing functional stereotactic surgery were included in the study and received propofol target-controlled infusion to achieve an initial steady state concentration of 1 microg/ml. Sedation was measured using the Ramsay Sedation Scale. Airway obstruction was measured using a four-category score. Blood samples were drawn for propofol measurement. Individual pharmacokinetic profiles were constructed nonparametrically using linear interpolation. Time course of sedation and respiratory effects were described with population pharmacodynamic models using NONMEM. The probability (P) of a given level of sedation or airway obstruction was related to the estimated effect-site concentration of propofol (Ce) using a logistic regression model. RESULTS: The concentrations predicted by the target-controlled infusion system generally exceeded the measured concentrations. The estimates of C(50) for Ramsay scores 3, 4, and 5 were 0.1, 1.02, and 2.28 microg/ml, respectively. For airway obstruction scores 2 and 3, the estimates of C(50) were 0.32 and 2.98 microg/ml, respectively. Estimates of k(e0) were 0.24 and 0.5 1/min for the sedation and respiratory effects, respectively. CONCLUSIONS: The pharmacokinetic behavior of propofol in patients with Parkinson disease differs with respect to the population from which the model used by the target-controlled infusion device was developed. Based on the results from the final models, a typical steady state plasma propofol concentration of 0.35 microg/ml eliciting a sedation score of 3 with only minimal, if any, airway obstruction has been defined as the therapeutic target

Reassessing the status of antiphospholipid syndrome in systemic lupus erythematosus.

The antiphospholipid syndrome was initially described in 1986. To reassess the validity of antiphospholipid antibodies in systemic lupus erythematosus (SLE), 95 patients with SLE were studied. Their antiphospholipid antibody profile was analysed and correlated with clinical findings such as thrombosis, abortions, or thrombocytopenia. A low prevalence of these antibodies was found (13 patients; 14%) with a high specificity for thrombosis (92%) and abortions (92%). The importance of anticardiolipin antibodies as a risk factor for thrombosis or abortions, or both, in patients with SLE is reaffirmed by this work