2,379 research outputs found
Critical dynamics of the Potts model: short-time Monte Carlo simulations
We calculate the new dinamic exponent of the 4-state Potts model,
using short-time simulations. Our estimates and 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
is calculated by an alternative way that mixes two different initial
conditions. We have also estimated the values of the static exponents
and . 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
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 by
following the time evolution of the probability that the considered
order parameter does not change its sign up to time . We have also obtained
the critical exponents , , , and 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
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
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 hÃdricas en la demanda evapotranspirativa
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 mayorÃa 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 Ãndices de vegetación (NDVI) y la elaboración de los correspondientes mapas estadÃsticos. El ensayo ha sido realizado en un viñedo experimental de cultivar Tempranillo (Vitis vinÃfera 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 Ãndices de vegetación mediante el uso de sensores multiespectrales cercanos, montados sobre vehÃculos 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 estadÃstica 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
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 sÃ. Este concepto
se cristalizó con el fin de describir los aspectos únicos de un lugar particular (suelo, topografÃa 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 topografÃa 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 asà 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, asà 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
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
We investigate the short-time critical dynamics of the Baxter-Wu (BW) and
Turban (3TU) models to estimate their global persistence exponent . 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 could be equal to zero
In situ crosslinked electrospun gelatin nanofibers for skin regeneration
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?
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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