Stable Equilibrium Based on L\'evy Statistics: Stochastic Collision Models Approach

We investigate equilibrium properties of two very different stochastic collision models: (i) the Rayleigh particle and (ii) the driven Maxwell gas. For both models the equilibrium velocity distribution is a L\'evy distribution, the Maxwell distribution being a special case. We show how these models are related to fractional kinetic equations. Our work demonstrates that a stable power-law equilibrium, which is independent of details of the underlying models, is a natural generalization of Maxwell's velocity distribution.Comment: PRE Rapid Communication (in press

Thermodynamic modeling of the LiF-YF3 phase diagram

A thermodynamic optimization of the LiF-YF3 binary phase diagram was performed by fitting the Gibbs energy functions to experimental data that were taken from the literature, as well as from own thermoanalytic measurements (DTA and DSC) on HF-treated samples. The Gibbs energy functions for the end member compounds were taken from the literature. Excess energy terms, which describe the effect of interaction between the two fluoride compounds in the liquid phase, were expressed by the Redlich-Kister polynomial function. The calculated phase diagram and thermodynamic properties for the unique formed compound, LiYF4, are in reasonable agreement with the experimental data.Comment: 4 pages, 3 figure

Fire Management In Veredas (palm Swamps): New Perspectives On Traditional Farming Systems In Jalapão, Brazil

The veredas (palm swamps) of the cerrado biome are legally protected as áreas de Preservação Permanente (Permanent Preservation Areas), and the use of fire in these wetlands is prohibited. We carried out a preliminary assessment of environmental impacts of the local use of agricultural fire in veredas through a collaborative research project in Jalapão (Tocantins, Brazil). We found that "roças de esgoto" (drained peat swamp swidden fields) form the basis of the agricultural system of this region. These fields ensure production throughout the year, provide more income than "roças de toco" (rainfed swidden fields), and may function as a repository of agrobiodiversity on a regional scale. This study suggests that the use of fire in veredas associated with roças de esgoto does not lead to significant deforestation, that is, to the disappearance of the forest physiognomy, but instead helps maintain tree cover during the fallow period, possibly accelerating natural succession.19326929

Multiple Aggressions Among Nestmates Lead to Weak Dominance Hampering Primitively Eusocial Behaviour in an Orchid Bee

Reproductive conflict expressed as aggression is common in social Hymenoptera. In eusocial species, as in honeybees, several mechanisms however alleviate the conflicts and reduce aggressive interactions. Unlike their sister group, the orchid bees do not exhibit eusocial behaviour. Instead, some of the species presents a primitively eusocial behaviour, with a single dominant female and fertile subordinate females participating on egg laying activities. In the current study we investigated the aggressive interactions of Euglossa annectans Dressler females through five generations of phylopatry and reuse of the natal nest. Although network analysis indicates that central individuals, those with more interactions, were more commonly the aggressors and others were more commonly the recipients, multiple attacks and several potential dominant females within the nest indicated a labile sociality. This suggests that there is an unstable social hierarchy in the species. Euglossa annectans, despite having overlapping generations, during which several individuals share a nest, there is no division of labour into reproductive females and interactions are often competitive. Aggressive behaviours conducted by multiple fertile females were often followed by egg, larvae or pupae replacement

Evaluation of the cardiovascular effects of vasicine, an alkaloid isolated from the leaves of Sida cordifolia L. (Malvaceae)

The cardiovascular effects of vasicine, an alkaloid isolated from the leaves of Sida cordifolia L., were evaluated in this work. In non-anaesthetized rats (n=6), vasicine (1, 2.5, 5 and 10 mg/kg; i.v., randomly) induced hypotension associated with an intense bradycardia. Both responses were completely abolished after atropine (2mg/Kg; i.v.) and attenuated after hexamethonium (20 mg/Kg; i.v.). In isolated rat mesenteric artery rings, vasicine (0.03, 0.1, 0.3, 1, 3, 10, 30, 100 and 300 μg/mL, cumulatively) induced concentration-dependent relaxation of phenylephrine-induced tone (IC50= 3.8±0.9 μg/mL; n = 6). In conclusion, the results show that vasicine produce hypotension and bradycardia which appears to be due to the stimulation of cardiac muscarinic receptors (directly and/or indirectly), and by a decrease of the peripheral resistances

Three-algebra for supermembrane and two-algebra for superstring

While string or Yang-Mills theories are based on Lie algebra or two-algebra structure, recent studies indicate that M-theory may require a one higher, three-algebra structure. Here we construct a covariant action for a supermembrane in eleven dimensions, which is invariant under global supersymmetry, local fermionic symmetry and worldvolume diffeomorphism. Our action is classically on-shell equivalent to the celebrated Bergshoeff-Sezgin-Townsend action. However, the novelty is that we spell the action genuinely in terms of Nambu three-brackets: All the derivatives appear through Nambu brackets and hence it manifests the three-algebra structure. Further the double dimensional reduction of our action gives straightforwardly to a type IIA string action featuring two-algebra. Applying the same method, we also construct a covariant action for type IIB superstring, leading directly to the IKKT matrix model.Comment: 1+15 pages, no figure; Refs added, Accepted for publication in JHE

Genetic deletion of ACE2 induces vascular dysfunction in C57BL/6 mice: role of nitric oxide imbalance and oxidative stress

Accumulating evidence indicates that angiotensin-converting enzyme 2 (ACE2) plays a critical role in cardiovascular homeostasis, and its altered expression is associated with major cardiac and vascular disorders. The aim of this study was to evaluate the regulation of vascular function and assess the vascular redox balance in ACE2-deficient (ACE2-/y) animals. Experiments were performed in 20-22 week-old C57BL/6 and ACE2-/y male mice. Evaluation of endothelium-dependent and -independent relaxation revealed an impairment of in vitro and in vivo vascular function in ACE2-/y mice. Drastic reduction in eNOS expression at both protein and mRNA levels, and a decrease in •NO concentrations were observed in aortas of ACE2-/y mice in comparison to controls. Consistently, these mice presented a lower plasma and urine nitrite concentration, confirming reduced •NO availability in ACE2-deficient animals. Lipid peroxidation was significantly increased and superoxide dismutase activity was decreased in aorta homogenates of ACE2-/y mice, indicating impaired antioxidant capacity. Taken together, our data indicate, that ACE2 regulates vascular function by modulating nitric oxide release and oxidative stress. In conclusion, we elucidate mechanisms by which ACE2 is involved in the maintenance of vascular homeostasis. Furthermore, these findings provide insights into the role of the renin-angiotensin system in both vascular and systemic redox balance

Interesting magnetic properties of Fe1−x_{1-x}Cox_xSi alloys

Solid solution between nonmagnetic narrow gap semiconductor FeSi and diamagnetic semi-metal CoSi gives rise to interesting metallic alloys with long-range helical magnetic ordering, for a wide range of intermediate concentration. We report various interesting magnetic properties of these alloys, including low temperature re-entrant spin-glass like behaviour and a novel inverted magnetic hysteresis loop. Role of Dzyaloshinski-Moriya interaction in the magnetic response of these non-centrosymmetric alloys is discussed.Comment: 11 pages and 3 figure

Body condition score, weight variation and reproductive performance of beef cows in rangelands from the Pantanal region

Objetivou-se avaliar a influência do escore de condição corporal (ECC) sobre a eficiência reprodutiva de vacas de cria nos períodos pré e pós-parto e a probabilidade de parição, usando o escore de condição corporal e a variação ponderal no período crítico do ciclo reprodutivo. Utilizaram-se 248 vacas multíparas mantidas em pastagens nativas distribuídas em quatro estratégias de suplementação: mistura mineral (controle); suplemento farelado; suplemento líquido; suplemento líquido para vacas e bezerros. As avaliações de peso e ECC, na escala de 1 a 9, foram realizadas no período crítico: em agosto (período pré-parto, 60-90 dias antes da parição) e em janeiro (período pós-parto e reprodutivo) durante quatro anos consecutivos. Para a análise dos anos consecutivos de reprodução, criou-se um escore de reprodução, ou seja, somou-se o número de parições de cada vaca durante os quatro anos pecuários avaliados. O escore de condição corporal nos períodos pré e pós-parto e a idade da vaca influenciaram o escore de reprodução. Portanto, para avaliação da probabilidade de parição, foram utilizadas todas as vacas, classificadas em paridas e vazias. Utilizando equações de estimação generalizadas (EEG), foi modelada a probabilidade de as matrizes serem classificadas como paridas considerando variáveis exploratórias ao longo do tempo. Para se obter probabilidade de parição superior a 80%, as vacas devem possuir escore de aproximadamente 5,5 no período pré-parto. Aproximadamente 60% das vacas paridas mantiveram ou ganharam peso no período crítico do ano, o que levou a maior probabilidade de reconcepção, similar ao observado para as vacas vazias, porém com probabilidade menor de parição. O período pré-parto é o melhor para estimar a probabilidade de parição das vacas por meio da avaliação do escore corporal. A seleção de vacas adaptadas às condições bioclimáticas do Pantanal aumenta a probabilidade de produção de um bezerro por vaca por ano. _________________________________________________________________________________ ABSTRACTThe aim of this study was to evaluate the influence of body condition score (BCS) on reproductive performance of beef cows before and after calving and to evaluate the calving probability using body condition score and weight variation during critical periods of the cow reproductive cycle. From 2001 to 2005, the body condition score was recorded in 248 multiparous cows raised in native pastures, submitted to different supplementation treatments (mineral mixture only - control; dry supplement; liquid supplement and liquid supplement for cow and calves). Weighing and body condition evaluation were made on a 1-9 point scale in August (prepartum period, 60-90 days before parturition) and January (postpartum and reproductive period). A reproduction score was created in function of the body scores in four consecutive years. Except for the treatment, the other factors (body condition score in the prepartum and postpartum periods and cow age) influenced the reproduction score. Thus, the calving probabilities were estimated for all cows. Generalized estimating equations (GEE) were used to evaluate the calving probability in function of the exploratory variables over time. Calving probability higher than 80% was obtained when cows scored 5,5 before calving. In relation to weight, the results showed that about 60% of calving cows maintained or gained weight in the postpartum period, leading to increase in the rebreeding probability. Similar situation occurred with single cows; however, the calving probability was lower. These results indicate that the calving probability using BCS is better estimated before calving. Furthermore, it indicates the presence of cows more adapted to the Pantanal climatic and feeding conditions than others