Self-organized patterns of coexistence out of a predator-prey cellular automaton

We present a stochastic approach to modeling the dynamics of coexistence of prey and predator populations. It is assumed that the space of coexistence is explicitly subdivided in a grid of cells. Each cell can be occupied by only one individual of each species or can be empty. The system evolves in time according to a probabilistic cellular automaton composed by a set of local rules which describe interactions between species individuals and mimic the process of birth, death and predation. By performing computational simulations, we found that, depending on the values of the parameters of the model, the following states can be reached: a prey absorbing state and active states of two types. In one of them both species coexist in a stationary regime with population densities constant in time. The other kind of active state is characterized by local coupled time oscillations of prey and predator populations. We focus on the self-organized structures arising from spatio-temporal dynamics of the coexistence. We identify distinct spatial patterns of prey and predators and verify that they are intimally connected to the time coexistence behavior of the species. The occurrence of a prey percolating cluster on the spatial patterns of the active states is also examined.Comment: 19 pages, 11 figure

Subcritical behavior in the alternating supercritical Domany-Kinzel dynamics

Cellular automata are widely used to model real-world dynamics. We show using the Domany-Kinzel probabilistic cellular automata that alternating two supercritical dynamics can result in subcritical dynamics in which the population dies out. The analysis of the original and reduced models reveals generality of this paradoxical behavior, which suggests that autonomous or man-made periodic or random environmental changes can cause extinction in otherwise safe population dynamics. Our model also realizes another scenario for the Parrondo's paradox to occur, namely, spatial extensions.Comment: 8 figure

Proposta de um modelo de utilização sustentável do solo para a instalação de novas culturas na Beira Baixa, Portugal: o caso do pistácio (Pistacia vera L.)

É consensual que a escolha dos usos mais adequados às aptidões edafo-climáticas, complementada com critérios socioeconómicos, promove uma utilização sustentável dos espaços rurais. Existem diferentes metodologias que permitem determinar a aptidão do solo para usos agroflorestais ou para a manutenção de ecossistemas seminaturais, nomeadamente culturas agrícolas, povoamentos florestais, territórios agro-silvo-pastoris e áreas críticas em termos de riscos de erosão hídrica ou outro risco natural. Neste estudo pretendeu-se determinar os diferentes níveis de aptidão para o cultivo do Pistácio (Pistacia vera L.), no território da Beira Baixa, delimitando as áreas que apresentam aptidão com base na análise dos fatores limitantes, nomeadamente: tipo de solo, precipitação, geadas na primavera (temperaturas mínimas nos meses de março, abril e maio), horas de frio, humidade relativa nos meses de verão e horas de calor. Para o efeito procedeu-se à identificação dos parâmetros biofísicos determinantes para o cultivo de Pistácio, bem como das condicionantes recorrendo à integração de um conjunto de fatores com recurso a um Sistema de Informação Geográfica. A avaliação da aptidão foi efetuada com recurso ao método de análise multicritério Analytical Hierachy Process (AHP). A metodologia utilizada divide o problema em níveis hierárquicos de tomada de decisão. Após a hierarquização do problema, em cada nível, os critérios que condicionam a tomada de decisão são comparados dois a dois (pairwise comparation) numa matriz de decisão quadrada, baseada numa escala de importância de nove valores numéricos. Para esta análise foi utilizada a extensão AHP. O processo AHP é concluído pela determinação da importância relativa de cada critério/subcritério e pela validação da consistência destas operações. A AHP mostrou-se adequada na avaliação da aptidão da área de estudo, por permitir a integração dos vários critérios estudados, sendo uma ferramenta interativa muito útil na análise do território, que possibilita a tomada de decisão e a resolução de problemas.info:eu-repo/semantics/publishedVersio

Organ-Preserving Surgery for Penile Carcinoma

Introduction. Penile carcinoma has traditionally been treated by either surgical amputation or radical radiotherapy, both associated with devastating anatomical, functional, and psychological impact on the patient's life. Innovative surgical techniques have focused on penile preservation in well-selected patients to minimize physical disfigurement and consequently maximize quality of life. The objective of this article is to define the current status of these organ-preserving surgical options for penile carcinoma. Materials and Methods. An extensive review of the Pubmed literature was performed to find articles discussing only reconstructive surgery which have contributed significantly to change traditional, frequently mutilating treatments, to develop less disfiguring surgery, and to improve patients' quality of life over the last two decades. Results. Several articles were included in this analysis in which a major contribution to the change in therapy was thought to have occurred and was documented as beneficial. Some articles reported novel techniques of less-mutilating surgery involving different forms of glans reconstruction with the use of flaps or grafts. The issue of safe surgical margins was also addressed. Conclusion. The development of less-disfiguring techniques allowing phallus preservation has reduced the negative impact on functional and cosmetic outcomes of amputation without sacrificing oncological objectives in appropriately selected patients based on stage, grade, and location of the tumour. Until more prospective studies are available and solid evidence is documented, organ preservation should be offered with caution

A bibliometric based analysis to identify promising domains of decarbonisation technologies

The high volume of research outputs related to technologies and strategies for decarbonisation can make it challenging to understand the relevance of the presented proposals. In this paper, a bibliometric-based analysis is proposed to understand better the domains and subdomains of decarbonisation technologies that have given more attention by the scientific community. The results show that carbon capture technologies, renewable energy sources, electric mobility, green hydrogen, and storage systems are the technology innovations that have received the most attention in the period 2013 to 2021. These results confirm the traditional supply-side orientation of research on technology innovations.info:eu-repo/semantics/acceptedVersio

Reduced Pain and Inflammation in Juvenile and Adult Rats Fed a Ketogenic Diet

The ketogenic diet is a high-fat, low-carbohydrate regimen that forces ketone-based rather than glucose-based cellular metabolism. Clinically, maintenance on a ketogenic diet has been proven effective in treating pediatric epilepsy and type II diabetes, and recent basic research provides evidence that ketogenic strategies offer promise in reducing brain injury. Cellular mechanisms hypothesized to be mobilized by ketone metabolism and underlying the success of ketogenic diet therapy, such as reduced reactive oxygen species and increased central adenosine, suggest that the ketolytic metabolism induced by the diet could reduce pain and inflammation. To test the effects of a ketone-based metabolism on pain and inflammation directly, we fed juvenile and adult rats a control diet (standard rodent chow) or ketogenic diet (79% fat) ad libitum for 3–4 weeks. We then quantified hindpaw thermal nociception as a pain measure and complete Freund's adjuvant-induced local hindpaw swelling and plasma extravasation (fluid movement from the vasculature) as inflammation measures. Independent of age, maintenance on a ketogenic diet reduced the peripheral inflammatory response significantly as measured by paw swelling and plasma extravasation. The ketogenic diet also induced significant thermal hypoalgesia independent of age, shown by increased hindpaw withdrawal latency in the hotplate nociception test. Anti-inflammatory and hypoalgesic diet effects were generally more robust in juveniles. The ketogenic diet elevated plasma ketones similarly in both age groups, but caused slowed body growth only in juveniles. These data suggest that applying a ketogenic diet or exploiting cellular mechanisms associated with ketone-based metabolism offers new therapeutic opportunities for controlling pain and peripheral inflammation, and that such a metabolic strategy may offer significant benefits for children and adults

Drivers for annual cork growth under two understory management alternatives on a podzolic cork oak stand

ArticleUnderstory management practices and stand density characteristics allow one to distinguish a cork oak traditional silvopastoral system (known as a montado) from a cork oak forest system. Although understanding the manner in which different management practices affect cork growth is imperative, there are still only a few outputs from experimental research that contribute to this knowledge. The effect of potential drivers on annual cork growth was analyzed using a linear mixed model approach. Two dimensions of drivers were considered: intraspecific competition, assessed by tree level distance-dependent indices; and interspecific competition, assessed by variables characterizing understory management. The present dataset was collected from an experimental trial established on a cork oak stand in Podzolic soil on the Tagus river basin, covering two different cork growth cycles over the period from 2003 to 2015. The adjusted models considered two understory management alternatives: spontaneous shrubs maintenance and forage application. In both models, annual precipitation displayed a positive effect on annual cork growth, as expected. However, no significant effect of intraspecific competition was found. Additionally, there was a positive effect on annual cork growth associated with the spontaneous shrubs growth and a negative effect associated with lupine presence; both effects linked to different cork ring ages’ thresholds. The study main contributions are the following: (i) the introduction of the interaction between cork growth cycle stage and understory management practices, only possible with cork sample collections from different cork rotation cycles; (ii) the finding that there was no significant effect of intraspecific competition on cork growthinfo:eu-repo/semantics/publishedVersio

Influência da estrutura da paisagem nas comunidades de passeriformes no centro de Portugal

O presente trabalho tem como objetivo identificar a relação existente entre as comunidades de passeriformes que nidificam na região Centro de Portugal e a composição e estrutura da paisagem desse território. Procurou-se, igualmente, verificar a importância da rugosidade do terreno na distribuição destas comunidades. Identificaram-se um conjunto de indicadores espaciais (métricas da paisagem e variáveis morfométricas) que, no seu conjunto, caracterizam a estrutura da paisagem, bem como as tipologias fisionómicas de habitat passíveis de determinar a distribuição das comunidades de passeriformes nidificantes. A informação referente ao uso e ocupação do solo foi processada no programa QGIS, com recurso ao plug-in LecoS. Os dados produzidos, juntamente com a informação referente à presença/ausência das espécies de aves, foram posteriormente submetidos a uma análise estatística multivariada com o intuito de correlacionar a ocorrência das espécies com a estrutura da paisagem e topografia. O desenvolvimento deste trabalho permitiu verificar que, embora seja possível obter resultados para as métricas da paisagem por classes de uso, existem no entanto limitações na obtenção de valores referentes às métricas para a matriz de uso na sua totalidade

Modeling the mechanical response of polycrystals deforming by climb and glide

This paper presents a crystallographically-based constitutive model of a single crystal deforming by climb and glide. The proposed constitutive law is an extension of the rate-sensitivity approach for single crystal plasticity by dislocation glide. Based on this description at single crystal level, a homogenization-based polycrystal model for aggregates deforming in a climb-controlled thermal creep regime is developed. To illustrate the capabilities of the proposed model, we present calculations of effective behavior of olivine and texture evolution of aluminum at warm temperature and low strain rate. In both cases, the addition of climb as a complementary single-crystal deformation mechanism improves the polycrystal model predictions

Chaotic hysteresis in an adiabatically oscillating double well

We consider the motion of a damped particle in a potential oscillating slowly between a simple and a double well. The system displays hysteresis effects which can be of periodic or chaotic type. We explain this behaviour by computing an analytic expression of a Poincar'e map.Comment: 4 pages RevTeX, 3 PS figs, uses psfig.sty. Submitted to Phys. Rev. Letters. PS file also available at http://dpwww.epfl.ch/instituts/ipt/berglund.htm