Modelling and controlling traffic behaviour with continuous Petri nets

Traffic systems are discrete systems that can be heavily populated. One way of overcoming the state explosion problem inherent to heavily populated discrete systems is to relax the discrete model. Continuous Petri nets (PN) represent a relaxation of the original discrete Petri nets that leads to a compositional formalism to model traffic behaviour. This paper introduces some new features of continuous Petri nets that are useful to obtain realistic but compact models for traffic systems. Combining these continuous PN models with discrete PN models of traffic lights leads to a hybrid Petri net model that is appropriate for predicting traffic behaviour, and for designing trac light controllers that minimize the total delay of the vehicles in the system

Steady State Analysis of Flexible Nets

The modeling and analysis of complex dynamic systems, such as those in manufacturing, logistics and biology, require powerful analysis methods for their study and optimization. A significant modeling and analysis challenge posed by both, artificial and natural systems, is the existence of uncertain parameters. Flexible Nets is a novel modeling formalism, inspired by Petri nets, that can handle different types of uncertain parameters in a natural way. This paper develops an efficient method to analyse the evolution of a system modeled by a Flexible Net in the long run. More precisely, the method focuses on the computation of steady state bounds for an objective function of interest. The method makes use of a set of constraints, expressed as linear inequalities, that the state variables must satisfy in the steady state. In order to account for systems that do not reach a constant steady state, the developed constraints allow the system state to switch among different values, i.e. the steady state variables are not forced to be constant.European Commission: FormalBio Contract No: 623995, Call reference: FP7-PEOPLE-2013-IE

Spatial and temporal distribution patterns of Anopheles arabiensis breeding sites in La Reunion Island - multi-year trend analysis of historical records from 1996-2009

<p>Abstract</p> <p>Background</p> <p>An often confounding facet of the dynamics of malaria vectors is the aquatic larval habitat availability and suitable conditions under which they can thrive. Here, we investigated the impact of environmental factors on the temporal and spatial distribution of larval habitats of <it>Anopheles </it><it>arabiensis </it>in different locations on La Reunion Island.</p> <p>Methods</p> <p>A retrospective examination was made from archival data which provided the complete enumeration of <it>An. arabiensis </it>breeding habitats in three distinct geographic zones - extending North-east, West and South of the island over 14 years, from January 1996 to December 2009. Data on the occurrence and the number of active larval habitats at each of a total of 4376 adjacent ellipsoid grid cells (216,506 square meters each) were used (1) to provide the geographic extent of breeding site availability from year to year and (2) to analyze associations with prevailing environmental factors, habitat types, and locations.</p> <p>Results</p> <p><it>Anopheles arabiensis </it>utilized a spectrum of man-made and natural aquatic habitats, most of which were concentrated primarily in the rock pools located in ravines and river fringes, and also in the large littoral marshes and within the irrigated agricultural zones. The numbers of breeding site per sampling grid differed significantly in different parts of the island. In contrast to an originally more widespread distribution across the island in the 1950s, detailed geographic analyses of the data obtained in the period extending from 1996-2009 showed an intriguing clustered distribution of active breeding sites in three discontinuous geographic zones, in which aquatic habitats availability fluctuates with the season and year. Seasonality in the prevalence of anopheles breeding sites suggests significant responsiveness to climatic factors.</p> <p>Conclusions</p> <p>The observed retreat of <it>An. arabiensis </it>distribution range to lower altitudinal zones (< 400 m) and the upward shift in the most remote littoral areas in the northeast and southwest regions suggest the possible influence of biogeographic factors, changes in land use and control operations. The results of this study would allow for a more rational implementation of control strategies across the island.</p

Why are anopheline mosquitoes not present in the Seychelles?

<p>Abstract</p> <p>Background</p> <p>Species of anopheline mosquitoes are largely distributed over emerged lands around the world and, within the tropics, few areas are without these insects, which are vectors of malaria parasites. Among the exceptions is the Seychelles archipelago in the western Indian Ocean. However, in the Aldabra island group, located in the extreme western portion of the archipelago, <it>Anopheles gambiae s.l. </it>was introduced, leading to massive proliferation and then elimination, with the most recent autochthonous malaria cases recorded in 1931.</p> <p>Methods</p> <p>In order to re-examine the absence of anopheline mosquitoes in the Seychelles, an entomological field survey was conducted in December 2008 at 17 sites on four granitic islands, including Mahé and Praslin, and ten sites on coralline atolls in the extreme west, including Aldabra.</p> <p>Results</p> <p>No evidence of larval or adult anophelines was found at the surveyed sites, which supports their absence in the Seychelles.</p> <p>Conclusions</p> <p>In the granitic islands of the Seychelles, the climate is favourable for anophelines. However, these islands are protected by their remoteness and prevailing seasonal winds. In addition, stagnant freshwater, required in anopheline larval development, is relatively uncommon on the granitic islands because of the steep slopes. In the southwestern atolls (Aldabra and Providence-Farquhar groups), the presence of a long dry season of up to nine months and the total absence of permanent natural freshwater prevents the breeding of anophelines and their successful colonization. The Seychelles does not have any native land mammals and like in other parts of the world (Antarctica, Iceland, New Caledonia, Central Pacific islands) their absence is associated with the lack of anophelines. This suggests an obligatory relationship for anophelines to feed on terrestrial mammals, without alternative for blood-feeding sources, such as bats, birds and reptiles.</p

Dietary intake of trans fatty acids in children aged 4–5 in Spain: The INMA cohort study

Trans fatty acid (TFA) intake has been identified as a health hazard in adults, but data on preschool children are scarce. We analyzed the data from the Spanish INMA Project to determine the intake of total, industrial and natural TFA, their main sources and the associated socio-demographic and lifestyle factors in children aged 4–5 (n = 1793). TFA intake was estimated using a validated Food Frequency Questionnaire, and multiple linear regression was used to explore associated factors. The mean daily intakes of total, industrial and natural TFA were 1.36, 0.60, and 0.71 g/day, respectively. Ten percent of the children obtained >1% of their energy intake from TFA. The main sources of industrial TFA were fast food, white bread and processed baked goods. Milk, red and processed meat and processed baked goods were the main sources of natural TFA. Having parents from countries other than Spain was significantly associated with higher natural TFA (in mg/day) intake (β 45.5) and television viewing was significantly associated with higher industrial TFA intake (β 18.3). Higher fruits and vegetables intake was significantly associated with lower intakes of all TFAs, whereas higher sweetened beverages intake was significantly associated with lower total and natural TFA intake. Thus, total and industrial TFA intake was associated with less healthy food patterns and lifestyles in Spanish preschool children

Epidemiology of Coxiella burnetii infection in Africa: a OneHealth systematic review

Background: Q fever is a common cause of febrile illness and community-acquired pneumonia in resource-limited settings. Coxiella burnetii, the causative pathogen, is transmitted among varied host species, but the epidemiology of the organism in Africa is poorly understood. We conducted a systematic review of C. burnetii epidemiology in Africa from a “One Health” perspective to synthesize the published data and identify knowledge gaps.&lt;p&gt;&lt;/p&gt; Methods/Principal Findings: We searched nine databases to identify articles relevant to four key aspects of C. burnetii epidemiology in human and animal populations in Africa: infection prevalence; disease incidence; transmission risk factors; and infection control efforts. We identified 929 unique articles, 100 of which remained after full-text review. Of these, 41 articles describing 51 studies qualified for data extraction. Animal seroprevalence studies revealed infection by C. burnetii (&#8804;13%) among cattle except for studies in Western and Middle Africa (18–55%). Small ruminant seroprevalence ranged from 11–33%. Human seroprevalence was &#60;8% with the exception of studies among children and in Egypt (10–32%). Close contact with camels and rural residence were associated with increased seropositivity among humans. C. burnetii infection has been associated with livestock abortion. In human cohort studies, Q fever accounted for 2–9% of febrile illness hospitalizations and 1–3% of infective endocarditis cases. We found no studies of disease incidence estimates or disease control efforts.&lt;p&gt;&lt;/p&gt; Conclusions/Significance: C. burnetii infection is detected in humans and in a wide range of animal species across Africa, but seroprevalence varies widely by species and location. Risk factors underlying this variability are poorly understood as is the role of C. burnetii in livestock abortion. Q fever consistently accounts for a notable proportion of undifferentiated human febrile illness and infective endocarditis in cohort studies, but incidence estimates are lacking. C. burnetii presents a real yet underappreciated threat to human and animal health throughout Africa.&lt;p&gt;&lt;/p&gt

Seguridad de la sedación profunda con propofol controlada por el endoscopista en la colangiopancreatografía retrógrada endoscópica (CPRE). Estudio prospectivo en un hospital terciario

Introducción: el propofol, administrado por el endoscopista con una enfermera entrenada, ha evolucionado como alternativa a la monitorización anestésica y es cada vez más frecuente en la práctica clínica habitual, incluso en endoscopia avanzada. Objetivo: evaluar la seguridad de la sedación profunda con propofol controlada por el endoscopista en pacientes sometidos a colangiopancreatografía retrógrada endoscópica (CPRE). Material y métodos: estudio prospectivo en los pacientes a los que se les realizó CPRE bajo sedación profunda con propofol. Se incluyeron diferentes variables relacionadas con el paciente y se registraron los datos iniciales y finales de la saturación de oxígeno (SatO2), la tensión arterial (TA), y la frecuencia cardiaca (FC) para determinar la presencia de eventos adversos a la sedación (hipoxemia, hipotensión o bradicardia). Resultados: un total de 661 pacientes fueron sometidos a CPRE bajo sedación con propofol durante un periodo de 24 meses. La tasa de eventos adversos registrada fue del 9, 7%. La más frecuente fue la hipoxemia (5, 7%), seguida de la bradicardia (2, 4%) y de la hipotensión (1, 6%). En el análisis univariante, la aparición de eventos adversos a la sedación (EAS) se asoció a una clasificación de ASA = III (p = 0, 026), a pacientes de edad más avanzada (p = 0, 009), mayor IMC (p = 0, 002) y a un tiempo de exploración más prolongado (p = 0, 034). La dosis de inducción de propofol también se relacionó con mayor probabilidad de eventos adversos (p = 0, 045), pero no la dosis total de propofol administrado (p = 0, 153). En el análisis de regresión logística multivariante, la edad, el índice de masa corporal (IMC) y la duración de la exploración se registran como predictores independientes de EAS (p < 0, 05). Conclusión: la sedación profunda con propofol controlada por personal de endoscopia entrenado es un método seguro en procedimientos endoscópicos complejos como la CPRE. Introduction: propofol administered by an endoscopist with a trained nurse has evolved as an alternative to anesthesia monitoring and is increasingly common in the routine clinical practice, even in advanced endoscopy. Objective: to evaluate the safety of deep sedation with endoscopist-controlled propofol in patients undergoing endoscopic retrograde cholangiopancreatography (ERCP). Material and methods: this was a prospective study in patients undergoing ERCP under deep sedation with propofol. Different patient-related variables were included and the initial and final data on oxygen saturation (SatO(2)) blood pressure (BP) and heart rate (HR) were recorded in order to determine the presence of adverse events due to sedation (hypoxemia, hypotension, or bradycardia). Results: a total of 661 patients underwent ERCP under sedation with propofol over a 24-month period. The rate of recorded adverse events was 9.7%. The most frequent adverse event was hypoxemia (5.7%), followed by bradycardia (2.4%) and hypotension (1.6%). According to the univariate analysis, the occurrence of adverse events due to sedation (AES) was associated with an ASA score >= III (p = 0.026), older patients (p = 0.009), higher body mass index (BMI) (p = 0.002) and a longer exploration time (p = 0.034). The induction dose of propofol was also associated with a greater likelihood of adverse events (p = 0.045) but not the total dose of propofol administered (p = 0.153). According to the multivariate logistic regression analysis, age, body mass index (BMI) and the duration of the exploration were independent predictors of SAE (p < 0.05). Conclusion: deep sedation with propofol controlled by trained endoscopy staff is a safe method in complex endoscopic procedures such as ERCP