2,379 research outputs found

    Critical dynamics of the Potts model: short-time Monte Carlo simulations

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    We calculate the new dinamic exponent θ\theta of the 4-state Potts model, using short-time simulations. Our estimates θ1=−0.0471(33)\theta_{1}=-0.0471(33) and θ2=% \theta_{2}= −0.0429(11)-0.0429(11) obtained by following the behavior of the magnetization or measuring the evolution of the time correlation function of the magnetization corroborate the conjecture by Okano et. al. In addition, these values agree with previous estimate of the same dynamic exponent for the two-dimensional Ising model with three-spin interactions in one direction, that is known to belong to the same universality class as the 4-state Potts model. The anomalous dimension of initial magnetization % x_{0}=z\theta +\beta /\nu is calculated by an alternative way that mixes two different initial conditions. We have also estimated the values of the static exponents β\beta and ν\nu . They are in complete agreement with the pertinent results of the literature.Comment: 12 pages, 7 figure

    An alternative order parameter for the 4-state Potts model

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    We have investigated the dynamic critical behavior of the two-dimensional 4-state Potts model using an alternative order parameter first used by Vanderzande [J. Phys. A: Math. Gen. \textbf{20}, L549 (1987)] in the study of the Z(5) model. We have estimated the global persistence exponent θg\theta_g by following the time evolution of the probability P(t)P(t) that the considered order parameter does not change its sign up to time tt. We have also obtained the critical exponents θ\theta, zz, ν\nu, and β\beta using this alternative definition of the order parameter and our results are in complete agreement with available values found in literature.Comment: 6 pages, 6 figure

    VINHOS QUE PENSAM - parte III|III GESTÃO NUTRICIONAL DA VINHA: SENSORES MULTIESPECTRAIS ATIVOS PRÓXIMOS

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    Os objetivos do presente trabalho: • caracterizar a concentração de N, P, K, Ca, Mg, Zn, Mn, e Fe da copa da vinha, baseada em observações multiespectrais e análises de plantas; • avaliar a possibilidade de utilização de sensores multiespectrais ativos próximos na gestão nutricional da vinha

    Evaluating The Effects Of Different Vegetation Types On Necrophagous Fly Communities (diptera: Calliphoridae; Sarcophagidae): Implications For Conservation

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    The present study was conducted in five different phytogeographic zones of the Brazilian state of Maranhão, three of which (the Amazon Forest, Cerrado, and Palm Groves) are more heterogeneous, whereas the other two (Marshlands and Mangroves) are more homogeneous. In each zone, nine sites were visited for the collection of necrophagous flies using bait traps in 2010, 2011, and 2012. The calliphorid and sarcophagid communities observed at each site were compared in terms of species richness, composition, and abundance. The more heterogeneous zones had higher species richness, except in the case of the sarcophagids in the forest habitats. The calliphorids Chloroprocta idioidea (Robineau-Desvoidy, 1830), Mesembrinella bicolor (Fabricius, 1805), Hemilucilia semi-diaphana (Rondani, 1850) and Lucilia eximia (Wiedemann, 1819) were more closely associated with the Cerrado, Palm Grove and Amazon Forest zones, and Chrysomya megacephala (Fabricius, 194) with the Mangrove. In the sarcophagids, Peckia (Euboettcheria) subducta (Lopes, 1935) and P. (Pattonella) palidipilosa (Curran & Walley, 1934) were associated with the Amazon Forest, and P. (Sarcodexia) lambens (Wiede-mann, 1830) and Tricharaea (Sarcophagula) occidua (Fabricius, 1794) with the Palm Grove and Cerrado zones. In the calliphorids, the greatest dissimilarity was recorded between the Amazon Forest and the Mangrove and Lowland grassland zones. In the sar-cophagids, by contrast, the greatest dissimilarities were recorded between the Amazon Forest and all the other four zones. In general, then, the phytogeographic zones with the highest environmental heterogeneity were characterized by the greatest species richness and abundance of necrophagous flies. © 2016 Pereira de Sousa et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.111

    Variabilidad espacial y temporal del vigor vegetativo en viñedo sin restricciones hídricas en la demanda evapotranspirativa

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    Aunque generalmente se asume que la respuesta de un cultivo a la dosis de riego seleccionada es homogénea en la totalidad del área cultivada, en la mayoría de los casos esto no se corresponde con la realidad. En este trabajo se presenta un estudio de la variabilidad espacial y temporal del vigor vegetativo en el cultivo del viñedo, mediante el uso de índices de vegetación (NDVI) y la elaboración de los correspondientes mapas estadísticos. El ensayo ha sido realizado en un viñedo experimental de cultivar Tempranillo (Vitis vinífera L.), donde se compararon cuatro bloques aleatorios con un tratamiento de riego al 100% de la demanda evapotranspirativa (ETc) del cultivo. Durante la fase de maduración, se realizaron semanalmente mapas de índices de vegetación mediante el uso de sensores multiespectrales cercanos, montados sobre vehículos terrestres. Se observó que la respuesta en el desarrollo vegetativo no mantuvo una homogeneidad espacio – temporal en las cuatro zonas de estudio, a pesar de haber recibido las mismas prácticas culturales. La utilización de este tipo de herramientas, sensores de vegetación y estadística inferencial, permite detectar zonas diferenciadas en el desarrollo vegetativo, pudiendo ser utilizado para la toma de decisiones sobre el manejo del cultivo, tales como el escalonamiento de la cosecha o la aplicación tanto de abonos como de fitosanitarios, en función del factor que produce dicho descenso de vegetación

    Micro-Terroir

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    El concepto de terroir en el vino está basado en la observación de que diferentes regiones, viñedos o secciones dentro del mismo viñedo, pueden producir vinos con identidades propias y muy diferentes entre sí. Este concepto se cristalizó con el fin de describir los aspectos únicos de un lugar particular (suelo, topografía y clima) que influyen y forman el vino que nace a partir de él. Para una misma posición geográfica, podemos pensar que factores tales como el suelo y la topografía son fijos, en el espacio y en el tiempo, sin embargo las plantas del cultivo de viñedo presentan microvariaciones locales con diversas respuestas adaptativas. En efecto, dentro de un mismo viñedo, aéreas aparentemente uniformes desde un punto de vista pedológico y topográfico presentan plantas con vigores vegetativos totalmente distintos, considerando todos los factores fijos. Estos micro – terroirs vegetativos proporcionan una diferenciación en la maduración de la uva, creando así una variación espacial y temporal en la calidad de la misma. Considerando los demás factores fijos y, partiendo del principio de que la variación espacial y temporal en el vigor vegetativo de una planta es un indicativo de su capacidad productiva, así como del potencial cualitativo del fruto, fueron controladas 80 hectáreas de viñedo mediante un sensor de vegetación. La base de datos, espacial y temporal, obtenida y posteriormente analizada por componentes principales, permitió elaborar zonas homogéneas de tratamiento que denominamos micro – terroirs. Como resultado, se encontró que existe una variabilidad espacial y temporal en las regiones aparentemente uniformes en términos pedológicos y topográficos, lo que sugiere una capacidad de adaptación genética que no siempre es fácil de tener en cuenta. La capacidad de monitorizar la variación espacial y temporal del vigor vegetativo de la vid, permitirá gestionar diferenciadamente las unidades geográficas distintas, desde el punto de vista de la calidad del vino

    Influence of chlorhexidine and zinc oxide in calcium hydroxide pastes on pH changes in external root surface

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    The objective of this study was to assess the influence of chlorhexidine (liquid and gel) and zinc oxide in calcium hydroxide (CH) pastes on root pH in simulated external resorption. One hundred human anterior teeth with a single root canal were selected. After decoronation and root canal instrumentation, the specimens were divided into 4 experimental groups and 1 control group (without intracanal paste): CH + saline (CH+S), CH + 2% chlorhexidine liquid (CH+ CHX), CH + 2% chlorhexidine gel (CH+ CHXg), and CH + 2% chlorhexidine gel + zinc oxide (CH+ CHXg+ZnO). pH was measured using a microelectrode at 3 and 24 h, and 1, 2, 3, and 4 weeks after inserting intracanal pastes. Data were analyzed statistically using an ANOVA and Tukey's test (p < 0.05). The CH+CHXg+ZnO group had the highest pH values throughout (p < 0.05). The CH+S and CH+ CHX groups had the highest pH values after 1 week and the CH+ CHXg group after 2 weeks. CH+ CHXg maintained the highest pH until the fourth week compared with CH+ CHX (p < 0.05). The control group remained at a neutral pH at all evaluated times. It can be concluded that chlorhexidine solution or gel maintained the alkaline pH of CH, and chlorhexidine gel allowed a slower decrease in pH over time. CH+ CHXg+ZnO showed the highest pH values and was an effective intracanal medication for maintaining alkaline root pH in the area of resorption3

    A comparative study of the dynamic critical behavior of the four-state Potts like models

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    We investigate the short-time critical dynamics of the Baxter-Wu (BW) and n=3n=3 Turban (3TU) models to estimate their global persistence exponent θg\theta _{g}. We conclude that this new dynamical exponent can be useful in detecting differences between the critical behavior of these models which are very difficult to obtain in usual simulations. In addition, we estimate again the dynamical exponents of the four-state Potts (FSP) model in order to compare them with results previously obtained for the BW and 3TU models and to decide between two sets of estimates presented in the current literature. We also revisit the short-time dynamics of the 3TU model in order to check if, as already found for the FSP model, the anomalous dimension of the initial magnetization x0x_{0} could be equal to zero

    In situ crosslinked electrospun gelatin nanofibers for skin regeneration

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    Due to its intrinsic similarity to the extracellular matrix, gelatin electrospun nanofibrous meshes are promising scaffold structures for wound dressings and tissue engineering applications. However, gelatin is water soluble and presents poor mechanical properties, which generally constitute relevant limitations to its applicability. In this work, gelatin was in situ crosslinked with 1,4-butanediol diglycidyl ether (BDDGE) at different concentrations (2, 4 and 6 wt%) and incubation time-points (24, 48 and 72 h) at 37 °C. The physico-chemical and biological properties of BDDGE-crosslinked electrospun gelatin meshes were investigated. Results show that by changing the BDDGE concentration it is possible to produce nanofibers crosslinked in situ with well-defined morphology and modulate fiber size and mechanical properties. Crosslinked gelatin meshes show no toxicity towards fibroblasts, stimulating their adhesion, proliferation and synthesis of new extracellular matrix, thereby indicating the potential of this strategy for skin tissue engineering.info:eu-repo/semantics/acceptedVersio

    Which are the best practices for MSc programmes in Sustainable Agriculture?

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    Programmes of education for sustainable development are important to reformulate and revise educa tional programmes in Sustainable Agriculture. Higher education institutes emerge as learning places to integrate sustainable development into the educational system, through graduation and MSc pro grammes, to provide a more effective response to the higher environmental and agriculture concerns. The aim of this study was to identify the best practices to be included in a MSc programme of education for sustainable development in agriculture based on a questionnaire prepared and distributed to agrarian sciences experts. The questionnaires were developed in order to define the fundamental competences/ expertise, to identify the best practices and the methods of training/learning that should be taken in consideration in a MSc programme in Sustainable Agriculture. The results showed that the fundamental expertise of MSc programmes should be based on knowledge transfer of agricultural measures to mitigate the impact of climate change on agricultural systems. MSc programmes in Sustainable Agri culture should include interdisciplinary courses related to sustainability and agro-environmental tech nologies, such as Precision Agriculture, and incorporate adaptive and mitigate practices as those used in the Circular Economy strategy. Traditional face-to-face training methods are considered the most important forms of training/learning in a MSc programme in Sustainable Agriculture. However, due to COVID-19 pandemic, online learning methods, traditionally considered not suitable for MSc programme in Sustainable Agriculture, became important by providing online education. Information and commu nication technology and technological tools showed to be important skills to effectively implement online learning and to improve the efficient access and use of up-to-date information of the agricultural sector
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