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Observed bimodal tree cover distributions at particular environmental conditions and theoretical models indicate that some areas in the tropics can be in either of the alternative stable vegetation states forest or savanna. However, when including spatial interaction in nonspatial differential equation models of a bistable quantity, only the state with the lowest potential energy remains stable. Our recent reaction-diffusion model of Amazonian tree cover confirmed this and was able to reproduce the observed spatial distribution of forest versus savanna satisfactorily when forced by heterogeneous environmental and anthropogenic variables, even though bistability was underestimated. These conclusions were solely based on simulation results for one set of parameters. Here, we perform an analytical and numerical analysis of the model. We derive the Maxwell point (MP) of the homogeneous reaction-diffusion equation without savanna trees as a function of rainfall and human impact and show that the front between forest and nonforest settles at this point as long as savanna tree cover near the front remains sufficiently low. For parameters resulting in higher savanna tree cover near the front, we also find irregular forest-savanna cycles and woodland-savanna bistability, which can both explain the remaining observed bimodality.

Background Botulinum toxin (BT) chemodenervation and anterior belly of digastric muscle (ABD) transfer are both treatment options in the management of an isolated marginal mandibular branch of the facial nerve (MMB) palsy. We compare the patient satisfaction following either BT injections or ABD transfer in the management of their isolated MMB palsy. Methods Patients in the ABD-arm of the study were identified retrospectively from September 2007 to July 2014. The patients in the BT-arm of the study were identified prospectively from those attending the clinic. Both groups of patients completed a validated patient satisfaction survey. Statistical analysis was performed and a P-value

Entomopathogenic fungus Beauveria bassiana is currently used as a biocontrol agent for agricultural pests. The infection process involves extracellular enzymes such as proteases and chitinases that degrade the cuticle of the insects. The objective of this work was to evaluate kinetic parameters of pH, temperature, ionic concentration and time of reaction on chitinases activity. The fungus B. bassiana CG432 was cultivated on coffee berry borer Hypothenemus hampei (Ferrari) and the conidia grown on insect were used to prepare the inoculum containing 108conídia/mL. These conidia were inoculated at 1% (v/v) in culture liquid medium containing D-glucose (10g), yeast extract (5g), NaNO3 (1,58g), Na2HPO4.7H2O (1,05g), KCl (1g), MgSO4.7H2O (0,6g) and KH2PO4 (0,36g) per liter. The cultivation was carried at 28°C and 180rpm during 5 days. Culture fluid was obtained by filtration and centrifugation at 8.000g, and the chitinases were isolated and concentrated by ultrafiltration using 10 and 100kDa cut off membranes under nitrogen pressure. Chitinase activity was detected and quantified using N-acetylglucosamine released by hydrolysis of colloidal chitin at 40 to 60ºC, at 50, 100 and 200 mM ionic concentrations of buffers sodium acetate (pH 4.0 to 6.0); sodium phosphate (pH 6.0 to 8.0); and Glycine-NaOH (pH 8.0 to 10.0) during 60 minutes. Maximum chitinase activity was at 45ºC and pH 5.5, and was also high at pH 6.0 and pH 8.5 using 50mM buffer. The chitinase activity increased and was stable during an hour at optimum conditions of the reaction, shown the stable nature of this enzyme.Beauveria bassiana é um fungo entomopatogênico utilizado no controle biológico de insetos-praga que infestam produtos agrícolas. O mecanismo de infecção envolve a produção de enzimas extracelulares, como proteases e quitinases que degradam a cutícula dos insetos. O objetivo deste trabalho foi avaliar parâmetros cinéticos de pH, temperatura, concentração iônica e tempo de reação sobre a atividade de quitinases. O fungo B. bassiana CG432 foi repicado em broca do café Hypothenemus hampei (Ferrari) e utilizado para preparar o inóculo contendo 108conídios ativados/mL. Estes conídios foram inoculados 1% (v/v) em meio de cultura líquido constituído por D-glicose (10g), extrato de levedura (5g), NaNO3 (1,58g), Na2HPO4.7H2O (1,05g), KCl (1g), MgSO4.7H2O (0,6g) e KH2PO4 (0,36g) por litro. O cultivo foi conduzido a 28°C e 180rpm durante 5 dias. O fluido extracelular do cultivo foi obtido por filtração e centrifugação a 8.000g, e as quitinases foram isoladas e concentradas por ultrafiltração entre membranas de 10 e 100kDa sob pressão de nitrogênio. A atividade das quitinases foi determinada pela quantificação da N-acetilglicosamina liberada pela hidrólise da quitina coloidal durante 60 minutos de incubação a temperaturas de 40 a 60ºC, concentrações iônicas dos tampões acetato de sódio pH 4,0 a 6,0; fosfato de sódio pH 6,0 a 8,0; e glicina-NaOH pH 8,0 a 10,0, a 50, 100 e 200 mM. A atividade das quitinases foi máxima a 45ºC, em pH 5,5, mas também foi elevada em pH 6,0 e 8,5 em concentração iônica de 50mM. A atividade de quitinases aumentou durante uma hora de incubação demonstrando estabilidade das enzimas nas condições ótimas da reação.

An asynchronous online discussion (AOD) is one format of instructional methods that facilitate student-centered learning. In the wealth of AOD research, this study evaluated how students' behavior on AOD influences their academic outcomes. This case study compared the differential analytic methods including web log mining, social network analysis and content analysis which were selected by three interaction patterns: person to system (P2S), person to person (P2P) and person to content (P2C) interaction. Forty-three undergraduate students participated in an online discussion forum for 12 weeks. Multiple regression analyses with the predictor variables from P2S, P2P and P2C and with a criterion variable of a final grade indicated several interesting findings. For P2S analysis, visits on board (VOB) had a significant variable to predict final grades. Also, the result of P2P analysis proved that in-degree and out-degree centrality predicted final grades. The P2C results based on cognitive presence represent that students' messages were mostly affiliated to the exploration and integration levels and also predicted the final grades. This study ultimately demonstrated the effectiveness of using multiple analytic methodologies to address and facilitate students' participation at AOD.