177 research outputs found

    Nonuniversality in the pair contact process with diffusion

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    We study the static and dynamic behavior of the one dimensional pair contact process with diffusion. Several critical exponents are found to vary with the diffusion rate, while the order-parameter moment ratio m=\bar{rho^2} /\bar{rho}^2 grows logarithmically with the system size. The anomalous behavior of m is traced to a violation of scaling in the order parameter probability density, which in turn reflects the presence of two distinct sectors, one purely diffusive, the other reactive, within the active phase. Studies restricted to the reactive sector yield precise estimates for exponents beta and nu_perp, and confirm finite size scaling of the order parameter. In the course of our study we determine, for the first time, the universal value m_c = 1.334 associated with the parity-conserving universality class in one dimension.Comment: 9 pages, 5 figure

    Sandpiles with height restrictions

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    We study stochastic sandpile models with a height restriction in one and two dimensions. A site can topple if it has a height of two, as in Manna's model, but, in contrast to previously studied sandpiles, here the height (or number of particles per site), cannot exceed two. This yields a considerable simplification over the unrestricted case, in which the number of states per site is unbounded. Two toppling rules are considered: in one, the particles are redistributed independently, while the other involves some cooperativity. We study the fixed-energy system (no input or loss of particles) using cluster approximations and extensive simulations, and find that it exhibits a continuous phase transition to an absorbing state at a critical value zeta_c of the particle density. The critical exponents agree with those of the unrestricted Manna sandpile.Comment: 10 pages, 14 figure

    Frecuencia de estereotipias clásicas en caballos de enduro

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    The objective of this study was to determine the frequency of classic stereotypies in endurance horses of Región Metropolitana (Chile) and the association of these abnormal behaviors with age and sex of the animals. All resident endurance horses from 8 equestrian centres of the Región Metropolitana were studied (n=107). A description of classic stereotipies (crib-biting, weaving and box-walking) was given to each horse keeper and then they were asked for this presence or absence, along the name, sex, age and breed, of every horse under their care. To analyze the data, horses were divided by age into 3 groups: 3 to 6 years (n=28), 7 to 9 years (n=42) and 10 to 18 years (n=37). Based on their sex, they were divided into 3 groups: stallions (n=11), geldings (n=64) and mares (n=32). Results are expressed as percentages. Fisher`s test with p < 0.05 was used for statistical analysis of the variables age and sex. A 12.2% of all horses presented stereotypies: crib-biting (0.9%), weaving (6.5%) and box-walking (4.7%). No relationship was found between the presence of stereotypies and variables age and sex. This study evidence a high frequency of classic stereotypies in endurance horses of Región Metropolitana, mostly weaving, and no found association between classic stereotypies and the variables age and sex of horses.El objetivo del estudio fue determinar la frecuencia de estereotipias clásicas en caballos de enduro de la Región Metropolitana (Chile) y la asociación de estas conducta anormales con la edad y sexo de los animales. Se estudió la totalidad de los caballos de enduro residentes en 8 centros ecuestres de la Región Metopolitana (n=107). A cada cuidador se le describió las estereotipias clásicas (aerofagia, balanceo y paseo circular en pesebrera) y luego se le consultó por su presencia-ausencia en los equinos a su cuidado, además del nombre, edad, sexo y raza de éstos. Para analizar los datos, los caballos fueron divididos por edad en 3 grupos: 3 a 6 años (n=28), 7 a 9 años (n=42) y 10 a 18 años (n=37). De acuerdo al sexo los caballos se dividieron en 3 grupos: machos enteros (n=11), machos castrados (n=64) y hembras (n=32). Los resultados son expresados como porcentajes simples y para el análisis estadístico de las variables edad y sexo se utilizó la prueba de Fisher con un nivel de significancia de p < 0,05. El 12,2% de todos los caballos presentaba estereotipias: aerofagia (0,9%), balanceo (6,5%) y paseo circular en pesebrera (4,7%). No se encontró asociación entre la presencia de estereotipias y las variables edad y sexo. Este estudio evidenció una alta frecuencia de estereotipias clásicas en caballos de enduro de la Región Metropolitana, principalmente balanceo, sin poder establecer asociación entre las estereotipias clásicas y las variables edad y sexo

    Pair contact process with a particle source

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    We study the phase diagram and critical behavior of the one-dimensional pair contact process (PCP) with a particle source using cluster approximations and extensive simulations. The source creates isolated particles only, not pairs, and so couples not to the order parameter (the pair density) but to a non-ordering field, whose state influences the evolution of the order parameter. While the critical point p_c shows a singular dependence on the source intensity, the critical exponents appear to be unaffected by the presence of the source, except possibly for a small change in beta. In the course of our study we obtain high-precision values for the critical exponents of the standard PCP, confirming directed-percolation-like scaling.Comment: 15 pages, 9 figure

    Fe3O4-Au Core-Shell Nanoparticles as a Multimodal Platform for In Vivo Imaging and Focused Photothermal Therapy

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    In this study, we report the synthesis of gold-coated iron oxide nanoparticles capped with polyvinylpyrrolidone (Fe@Au NPs). The as-synthesized nanoparticles (NPs) exhibited good stability in aqueous media and excellent features as contrast agents (CA) for both magnetic resonance imaging (MRI) and X-ray computed tomography (CT). Additionally, due to the presence of the local surface plasmon resonances of gold, the NPs showed exploitable “light-to-heat” conversion ability in the near-infrared (NIR) region, a key attribute for effective photothermal therapies (PTT). In vitro experiments revealed biocompatibility as well as excellent efficiency in killing glioblastoma cells via PTT. The in vivo nontoxicity of the NPs was demonstrated using zebrafish embryos as an intermediate step between cells and rodent models. To warrant that an effective therapeutic dose was achieved inside the tumor, both intratumoral and intravenous routes were screened in rodent models by MRI and CT. The pharmacokinetics and biodistribution confirmed the multimodal imaging CA capabilities of the Fe@AuNPs and revealed constraints of the intravenous route for tumor targeting, dictating intratumoral administration for therapeutic applications. Finally, Fe@Au NPs were successfully used for an in vivo proof of concept of imaging-guided focused PTT against glioblastoma multiforme in a mouse model.Spanish Ministry of Economy, Industry and Competitiveness (CTQ2017-86655-R and BIO2017-84246-C2-1-R)Fondo Social de la DGA (grupos DGA) and by the Regional Ministry of Health of Andalusia (OH-0026-2018).Associate Laboratory for Green Chemistry—LAQVApplied Molecular Biosciences Unit –UCIBIOPortuguese national funds from FCT/MCTES (UIDB/04378/2020 and UIDB/50006/2020

    Marketing motivations influencing food choice in 16 countries: segmentation and cluster analysis.

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    Food behaviour is governed by different kinds of motivations, some of individual nature and others related with the external food environment. This study investigated the eating motivations in sixteen countries with respect to commercial and marketing influences on food choices. The questionnaire survey was developed between September 2017 and June 2018, via online tools, targeting a convenience sample of residents in sixteen countries (Argentina, Brazil, Croatia, Egypt, Greece, Hungary, Italy, Latvia, Lithuania, Netherlands, Poland, Portugal, Romania, Serbia, Slovenia and the United States of America). The number of valid responses received was 11,919 participants. The data were treated using SPSS software, and the main statistical techniques used included exploratory factor analysis, evaluation of internal reliability through Cronbach’s alpha, cluster analysis (hierarchical and k-means) and logistic regression. The results obtained showed two groups of people: low motivated and notably motivated consumers. The results showed high asymmetries between countries, with highest percentage of highly motivated consumers in Egypt and the lowest percentage of highly motivated in Portugal. It was further observed that consumers more influenced by commercial and marketing aspects (the notably motivated) tend to be women, young, single, less educated, less likely to be professionally active, and those who live mostly in rural or suburban areas. Less exercise and overweight are also factors associated with greater propensity for commercial and marketing motivations. Furthermore, health problems such as shellfish or gluten intolerance, hypertension and high cholesterol confer less propensity to be in the segment of the notably motivated consumers. In conclusion, this work highlighted the role of geographic, sociodemographic and lifestyle factors as food choice determinants.info:eu-repo/semantics/publishedVersio

    IFNL4 ss469415590 polymorphism is associated with unfavourable clinical and immunological status in HIV-infected individuals

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    AbstractThe IFNL4 ss469415590 polymorphism, in high linkage disequilibrium with the IL28B rs12979860 variant, has been associated with hepatitis C virus clearance. We evaluated whether ss469415590 is associated with clinical and immunovirological parameters in human immunodeficiency virus-infected subjects. We found an independent association of the IFNL4 ss469415590 polymorphism with higher prevalence of AIDS-defining illnesses and lower CD4 T cell numbers. These results suggest the existence of common host defence mechanisms against different viral infections

    The non-equilibrium phase transition of the pair-contact process with diffusion

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    The pair-contact process 2A->3A, 2A->0 with diffusion of individual particles is a simple branching-annihilation processes which exhibits a phase transition from an active into an absorbing phase with an unusual type of critical behaviour which had not been seen before. Although the model has attracted considerable interest during the past few years it is not yet clear how its critical behaviour can be characterized and to what extent the diffusive pair-contact process represents an independent universality class. Recent research is reviewed and some standing open questions are outlined.Comment: Latexe2e, 53 pp, with IOP macros, some details adde

    Wild deer (Pudu puda) from Chile harbor a novel ecotype of Anaplasma phagocytophilum

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    [Background] Deer species play an important role in the enzootic cycles of several Anaplasma species. While in the Northern Hemisphere ticks of genus Ixodes are well recognized vectors of these intracellular bacteria, less is known regarding the biological cycles of Anaplasma spp. in South America.[Methods] Using PCR protocols and Sanger sequencing, we assessed the presence of Anaplasma spp. in blood and ticks collected on a native deer species (Pudu puda) from southern Chile.[Results] Based on phylogenetic analyses of the 16S rRNA, gltA and groEL genes and calculation of average sequence divergence for groEL, our results bring to light a novel genovariant of Anaplasma phagocytophilum (named strain “Patagonia”). The strain represents a novel ecotype within the A. phagocytophilum species complex and was detected in both P. puda and their ticks. Using a larger matrix, denser taxon sampling and outgroup, our maximum-likelihood- and Bayesian-inferred phylogenies for groEL provide an accurate picture of the topology of A. phagocytophilum ecotypes and their evolutionary relationships.[Conclusions] This is the first report of an ecotype of A. phagocytophilum in South America. Our results provide novel insight into the genetic diversity and ecology of this complex of bacterial lineages. Further studies should elucidate the enzootic cycle of A. phagocytophilum strain “Patagonia” and assess its pathogenic potential for pudues, domestic animals and humans in the region.This study was funded by the “Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)” No. 11220177, and by the ANID BECAS/Scholarship Program/DOCTORADO NACIONAL/2019–21190078 and 2020–21200182. Funders had no role in the study design, data collection, analysis, preparation of the manuscript and decision to publish. The contribution of JEU was funded by the Atracción Talento de la Comunidad de Madrid Fellowship Program (REFF 2019-T2/AMB-13166).Peer reviewe
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