62 research outputs found

    Statistical Laws in Urban Mobility from microscopic GPS data in the area of Florence

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    The application of Statistical Physics to social systems is mainly related to the search for macroscopic laws, that can be derived from experimental data averaged in time or space,assuming the system in a steady state. One of the major goals would be to find a connection between the statistical laws to the microscopic properties: for example to understand the nature of the microscopic interactions or to point out the existence of interaction networks. The probability theory suggests the existence of few classes of stationary distributions in the thermodynamics limit, so that the question is if a statistical physics approach could be able to enroll the complex nature of the social systems. We have analyzed a large GPS data base for single vehicle mobility in the Florence urban area, obtaining statistical laws for path lengths, for activity downtimes and for activity degrees. We show also that simple generic assumptions on the microscopic behavior could explain the existence of stationary macroscopic laws, with an universal function describing the distribution. Our conclusion is that understanding the system complexity requires dynamical data-base for the microscopic evolution, that allow to solve both small space and time scales in order to study the transients.Comment: 17 pages, 14 figures .jpg, use imsart.cl

    Predicting epidemic risk from past temporal contact data

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    Understanding how epidemics spread in a system is a crucial step to prevent and control outbreaks, with broad implications on the system's functioning, health, and associated costs. This can be achieved by identifying the elements at higher risk of infection and implementing targeted surveillance and control measures. One important ingredient to consider is the pattern of disease-transmission contacts among the elements, however lack of data or delays in providing updated records may hinder its use, especially for time-varying patterns. Here we explore to what extent it is possible to use past temporal data of a system's pattern of contacts to predict the risk of infection of its elements during an emerging outbreak, in absence of updated data. We focus on two real-world temporal systems; a livestock displacements trade network among animal holdings, and a network of sexual encounters in high-end prostitution. We define the node's loyalty as a local measure of its tendency to maintain contacts with the same elements over time, and uncover important non-trivial correlations with the node's epidemic risk. We show that a risk assessment analysis incorporating this knowledge and based on past structural and temporal pattern properties provides accurate predictions for both systems. Its generalizability is tested by introducing a theoretical model for generating synthetic temporal networks. High accuracy of our predictions is recovered across different settings, while the amount of possible predictions is system-specific. The proposed method can provide crucial information for the setup of targeted intervention strategies.Comment: 24 pages, 5 figures + SI (18 pages, 15 figures

    A general model of dioxin contamination in breast milk: results from a study on 94 women from the Caserta and Naples areas in Italy.

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    BackgroundThe Caserta and Naples areas in Campania Region experience heavy environmental contamination due to illegal waste disposal and burns, thus representing a valuable setting to develop a general model of human contamination with dioxins (PCDDs-PCDFs) and dioxin-like-PCBs (dl-PCBs).Methods94 breastfeeding women (aged 19-32 years; mean age 27.9 ± 3.0) were recruited to determine concentrations of PCDDs-PCDFs and dl-PCBs in their milk. Individual milk samples were collected and analyzed according to standard international procedures. A generalized linear model was used to test potential predictors of pollutant concentration in breast milk: age, exposure to waste fires, cigarette smoking, diet, and residence in high/low risk area (defined at high/low environmental pressure by a specific 2007 WHO report). A Structural Equation Model (SEM) analysis was carried out by taking into account PCDDs-PCDFs and dl-PCBs as endogenous variables and age, waste fires, risk area and smoking as exogenous variables.ResultsAll milk samples were contaminated by PCDDs-PCDFs (8.6 pg WHO-TEQ/98g fat ± 2.7; range 3.8-19) and dl-PCBs (8.0 pg WHO-TEQ/98g fat ± 3.7; range 2.5-24), with their concentrations being associated with age and exposure to waste fires (p < 0.01). Exposure to fires resulted in larger increases of dioxins concentrations in people living in low risk areas than those from high risk areas (p < 0.01).ConclusionsA diffuse human exposure to persistent organic pollutants was observed in the Caserta and Naples areas. Dioxins concentration in women living in areas classified at low environmental pressure in 2007 WHO report was significantly influenced by exposure to burns

    Brucella abortus Strain RB51 Vaccine: Immune Response after Calfhood Vaccination and Field Investigation in Italian Cattle Population

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    Immune response to Brucella abortus strain RB51 vaccine was measured in cattle vaccinated at calfhood. After an increase at day 6 post-vaccination (pv), the antibody level recorded in the 10 vaccinated animals remained constant for two months, and then progressively decreased. All vaccinated animals remained negative from day 162 pv to the end of the study (day 300 pv). Only at days 13 and 14 pv the RB51-CFT showed 100% sensitivity (credibility interval (CI) 76.2%–100%). The results indicate that the possibility to use RB51-CFT for the identification of cattle vaccinated at calfhood with RB51 is limited in time. A field investigation was carried out on 26,975 sera collected on regional basis from the Italian cattle population. The study outcomes indicate that in case of RB51-CFT positive results observed in officially Brucellosis-free (OBF) areas and, in any case, when an illegal use of RB51 vaccine is suspected, the use of the RB51-CFT alone is not sufficient to identify all the vaccinated animals. The design of a more sophisticated diagnostic protocol including an epidemiological investigation, the use of RB51-CFT, and the use of the skin test with RB51 as antigen is deemed more appropriate for the identification of RB51 vaccinated animals

    Epidemiology of West Nile in Europe and in the Mediterranean Basin

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    In the last 30 years several cases of West Nile (WN) virus infection were reported in horses and humans in Europe and in the Mediterranean Basin. Most of them were determined by strains of the Lineage 1 included in the European Mediterranean/Kenyan cluster. Strains of this cluster are characterised by a moderate pathogenicity for horses and humans and limited or no pathogenicity for birds. In recent years, however, WN cases determined by strains grouped in the Israeli/American cluster of Lineage 1 or in the lineage 2 have been reported in Hungary and Austria. The role of migrating birds in introducing new viruses to Europe has been often demonstrated. The migratory birds, which may be infected in their African wintering places, carry the virus northward to European sites during spring migrations. In the past, the virus introduction determined occasional cases of WN. In the recent years, new epidemiological scenarios are developing. In few occasions it has been evidenced the capability of WNV strains of overwintering by using local birds and mosquitoes. Species of Culex amongst mosquitoes and magpies (Pica pica), carrion crows (Corvus corone) and rock pigeons (Columba livia) amongst resident birds are the most probable species involved in this hypothetical WND endemic cycle

    Quantitative assessment of the probability of bluetongue virus overwintering by horizontal transmission : application to Germany

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    Even though bluetongue virus (BTV) transmission is apparently interrupted during winter, bluetongue outbreaks often reappear in the next season (overwintering). Several mechanisms for BTV overwintering have been proposed, but to date, their relative importance remain unclear. In order to assess the probability of BTV overwintering by persistence in adult vectors, ruminants (through prolonged viraemia) or a combination of both, a quantitative risk assessment model was developed. Furthermore, the model allowed the role played by the residual number of vectors present during winter to be examined, and the effect of a proportion of Culicoides living inside buildings (endophilic behaviour) to be explored. The model was then applied to a real scenario: overwintering in Germany between 2006 and 2007. The results showed that the limited number of vectors active during winter seemed to allow the transmission of BTV during this period, and that while transmission was favoured by the endophilic behaviour of some Culicoides, its effect was limited. Even though transmission was possible, the likelihood of BTV overwintering by the mechanisms studied seemed too low to explain the observed re-emergence of the disease. Therefore, other overwintering mechanisms not considered in the model are likely to have played a significant role in BTV overwintering in Germany between 2006 and 2007

    Diversidad de razas caprinas criollas en Argentina

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    Se estima que el 90% de los casi cinco millones de caprinos en Argentina se pueden asignar a poblaciones locales tradicionalmente llamadas Criollos. Se denomina así a un colectivo indefinido, menospreciado en sus atributos fenotípicos y productivos característicos, originados a partir de selección por diferentes etnias y en general adaptados a ambientes disímiles y hostiles de crianza. Con el objetivo de determinar las características diferenciales de razas locales o biotipos dentro de las Criollas contribuyendo a su valoración como recurso genético, se recuperaron trabajos de caracterización fenotípica realizados desde el año 2000 hasta el 2013. Se construyó una base datos a partir de las originales, con 19 variables cualitativas y cuantitativas de 2170 hembras de 6 poblaciones locales: Criollas de Formosa (FOR), Córdoba (CBA), La Rioja (LRI), San Luis (SLU), Neuquén (NQN) y Colorada Pampeana (LPA). Se analizó en forma descriptiva y multivariada para detectar diferencias y similitudes entre ellas. Los resultados mostraron rasgos compartidos (perfil recto; orejas horizontales) y divergentes (tipo de pelaje, perímetro de la caña). Los conglomerados formados en base al análisis factorial de datos mixtos muestran una clara diferenciación para FOR, LPA y NQN. CBA muestra rasgos de cruzamientos con Anglo Nubian, LRI y SLU se muestran dispersas. Se formaron 4 clústeres con buena definición para FOR, LPA, CBA y NQN. Se concluye que las razas Criolla Formoseña, Neuquina y Colorada Pampeana alcanzan un grado de diferenciación fenotípico significativo. LRI y SLU no muestran clara diferenciación y la CBA evidencia signos de cruzamientos con razas comerciales y riesgo de erosión genética.It is estimated that 90% of the almost five million goats in Argentina are local populations traditionally called Criollo. This designation refers to goats whose phenotypic and productive attributes are neglected. These populations have different origins and were selected by diverse rural communities; however, they share some common characteristics, such as being adapted to harsh environmental conditions and being bred in arid areas. In order to determine the differential traits of local breeds within Criollo and contribute to their assessment as a local genetic resource, phenotypic characterization research carried out in the last decades were recovered. A database was built, with 19 qualitative and quantitative variables of 2170 females from 6 local populations: Criolla de Formosa (FOR), Córdoba (CBA), La Rioja (LRI), San Luis (SLU), Neuquén (NQN) and Colorada Pampeana (LPA). They were analysed descriptively and by multivariate analysis in order to define differences and similarities among them. The results showed shared (straight profile, horizontal ears) and divergent (type of coat, shin circumference) features. The conglomerates formed on the basis of the mixed data factor analysis showed a clear differentiation for FOR, LPA and NQN. CBA showed evidence of crossing with Anglo Nubian, while LRI and SLU were scattered. Four Clusters with good definition were formed for FOR, LPA, CBA and NQN. It is concluded that FOR, NQN and LPA populations have achieved a significant degree of phenotypic differentiation. The LRI and SLU did not show a clear differentiation and the CBA showed signs of crossing with commercial breeds and risk of genetic erosion.Estación Experimental Agropecuaria BarilocheFil: Lanari, María Rosa. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche; ArgentinaFil: Giovannini, Nicolas. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche; ArgentinaFil: Maizon, Daniel Omar. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Anguil; ArgentinaFil: Deza, Maria C.V. Universidad Nacional de Cordoba. Facultad de Ciencias Agropecuarias; ArgentinaFil: Bedotti, Daniel Osvaldo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Anguil; ArgentinaFil: de la Rosa-Carbajal, Sebastian Arnoldo. Centro de Validacion Laguna Yema; ArgentinaFil: Vera, Tomas Anibal. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Investigación y Desarrollo Tecnológico para la Agricultura Familiar. Región NOA; ArgentinaFil: Ricarte, Ramon Armando. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria La Rioja; ArgentinaFil: Mezzadra, Carlos Alberto. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentin

    West Nile virus Epidemic in Horses, Tuscany Region, Italy

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    During the late summer of 1998, veterinary authorities in Tuscany, Italy, received reports of cases of neurologic disease among horses residing in a large wetland area located in the provinces of Florence and Pistoia. West Nile virus was isolated from two of the six horses that died or were euthanized. A retrospective epidemiologic study identified 14 clinical neurologic cases that occurred from August 20 to October 6 (attack rate of 2.8%). A serologic survey conducted over a 700-km2 area in stables with and without apparent clinical cases confirmed a wider spread of the infection, with an overall seroprevalence rate of 38% in the affected area. No significant differences in age-specific prevalence were observed, suggesting that the horses residing in the area had not been exposed previously to West Nile virus and supporting the hypothesis of its introduction in the wetland area during the first half of 1998
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