P-31 Sufficient Conditions for the Existence of Positive Solutions to an Elliptic Model

We study the existence of solutions to a general elliptic model. Specifically, we give conditions for the existence and non-existence of steady-state solutions to a general, nonlinear population model of two cooperating species

A General Elliptic Nonlinear System of Multiple Functions with Application

The purpose of this paper is to give a sufficient condition for the existence, nonexistence and uniqueness of positive solutions to a rather general type of elliptic system of the Dirichlet problem on a bounded domain Ω in Rn . We also investigate the effects of perturbation on the positive solutions to the system. The techniques used in this paper are upper-lower solutions, eigenvalues of operators, the maximum principles and spectrum estimates. The arguments also rely on some detailed properties for the solution of logistic equations. This result yields an algebraically computable criterion for the positive coexistence of competing species of animals in many biological models

Positive Solutions to a General Elliptic System with Smooth Functions

The purpose of this research is to give a sufficient condition for the existence and nonexistence of positive solutions to a rather general type of elliptic system of the Dirichlet problem on a bounded domain. This research was supported by the Office of Research and Creative Scholarship. The techniques used include upper-lower solutions, eigenvalues of operators, maximum principles, and spectrum estimates. The arguments also rely on some detailed properties of the solutions of logistic equations. These results yields algebraically computable criteria for the positive coexistence of competing species of animals in many biological models

Region of Smooth Functions for Positive Solutions to an Elliptic Biological Model

The non-existence and existence of the positive solution to the generalized elliptic model ∆u+g(u v) = 0 in Ω, ∆v+h(u, v) = 0 in Ω, u=v= 0 on∂Ω, were investigated

A General Elliptic Nonlinear System of Two Functions with Application

The purpose of this paper is to give a sufficient condition for the existence and nonexistence of positive solutions to a rather general type of elliptic system of the Dirichlet problem on the bounded domain Ω in Rn. Also considered are the effects of perturbations on the coexistence state and uniqueness. The techniques used in this paper are upper-lower solutions, eigenvalues of operators, maximum principles and spectrum estimates. The arguments also rely on some detailed properties for the solution of logistic equations. These results yield an algebraically computable criterion for the positive coexistence of competing species of animals in many biological models

Gasoline Prices and Their Relationship to Drunk-Driving Crashes

his study investigates the relationship between changing gasoline prices and drunk-driving crashes. Specifically, we examine the effects of gasoline prices on drunk-driving crashes in Mississippi by age, gender, and race from 2004Ð2008, a period experiencing great fluctuation in gasoline prices. An exploratory visualization by graphs shows that higher gasoline prices are generally associated with fewer drunk-driving crashes. Higher gasoline prices depress drunk- driving crashes among younger and older drivers, among male and female drivers, and among white, black, and Hispanic drivers. The statistical results suggest that higher gasoline prices lead to lower drunk-driving crashes for female and black drivers. However, alcohol consumption is a better predictor of drunk-driving crashes, especially for male, white, and older drivers.Drunk-driving crashes, gasoline prices, alcohol consumption, Mississippi

Link2Practice: A Model of Ongoing Teacher and Teacher Candidate Professional Learning

A common complaint about teacher education programs is that it follows a linear model—where theory and teaching skills are learned at the university and then applied in practicum experiences—that is inadequate and does not accurately represent teacher candidates’(TC) experiences (Brouwer & Korthagen, 2005; Korthagen, Loughran & Russell, 2006). Indeed, teacher education programs have long been faced with the challenge of a “theory/practice divide”, creating what has been seen as a mechanistic separation between university programs (where it is implied theory is learned) and the practicum (where it is implied skills and strategies are learned). This divide continues once teacher candidates become teachers in their own classrooms, where the divide further widens by valuing of the practical over the theoretical. We need a new frame of reference to understand teacher education as a whole (throughout a professional career), as emerging from interconnected, non-linear, and at times unpredictable structures. Teacher education programs should form in relation to teacher professional learning, student learning, and the realities of dynamically evolving modern-day schools. In our institutions, the ongoing tension between learning sites of campus and schools is reduced in the teacher education partnership called Link2Practice, where TCs’ courses are integrated in a school district program with teachers who are making inquiries into their practice. This partnership responds to the increasing need for educators to understand and remain current about the interactions between TCs, K-12 public schools’ students and the pedagogy practices, informed by theory, that they advocate. This paper describes the development of the Link2Practice model and discusses its importance for teacher education. Keywords: Teacher education; partnerships; integration; professional learning On reproche souvent aux programmes de formation des enseignants de suivre un modèle linéaire—selon lequel la théorie et les compétences pédagogiques sont acquises à l’université pour ensuite être appliquées pendant les stages—qui est inadéquat et qui ne représente pas avec exactitude les expériences des stagiaires (Brouwer & Korthagen, 2005; Korthagen, Loughran & Russell, 2006). En effet, les programmes de formation des enseignants font face depuis longtemps au défi que représente l’écart entre la théorie et la pratique ayant créé ce qu’on perçoit comme étant une séparation mécaniste entre les programmes universitaires (où il est sous-entendu que les étudiants apprennent la théorie) et les stages (où il est sous-entendu que les étudiants apprennent des habiletés et des stratégies). Cet écart se poursuit quand les stagiaires commencent à enseigner dans leur propre salle de classe et se creuse par la valorisation de la pratique aux dépens de la théorie. Il nous faut un nouveau cadre de référence qui permettra de comprendre la formation des enseignants dans son ensemble (tout au long de la carrière d’enseignant) comme produit de structures interconnectées, non linéaires et parfois imprévisibles. Les programmes de formation des enseignants devraient exister en relation avec le perfectionnement professionnel des enseignants, l’apprentissage des élèves et les réalités des écoles modernes en évolution dynamique. Dans nos institutions, la tension constante entre les deux sites d’apprentissage—le campus et les écoles—est réduit grâce à un partenariat éducatif nommé Link2Practice par lequel les stagiaires sont intégrés dans un programme de district scolaire avec des enseignants qui font enquête sur leur pratique. Ce partenariat répond au besoin croissant qu’ont les enseignants de comprendre les interactions entre les stagiaires, les élèves M-12 des écoles publiques et les pratiques pédagogiques informées par la théorie qu’ils préconisent, et de rester au courant de ces interactions. Cet article décrit le développement du modèle Link2Practice et discute de son importance dans la formation des enseignants. Mots clés : formation des enseignants; partenariats; intégration; perfectionnement professionne

Representações culturais e virtuais do sistema negocial português

Mestrado em Estudos InglesesO presente trabalho propõe-se abordar a descrição das representações culturais existentes numa comunidade discursiva virtual, que utiliza a língua inglesa e que foca os aspectos do sistema empresarial e negocial Português. Procura identificar e descrever estas representações culturais, utilizando uma metodologia etnográfica e técnicas de análise de discurso, representações essas que são comparadas com as existentes nos membros de um subgrupo da comunidade empresarial alvo, constituída por alunos de línguas e relações empresariais. Esta comparação tem como objectivo pedagógico a elaboração de recomendações para conteúdos programáticos.This dissertation addresses the description of the cultural representations held by an English language online discourse community centred on the Portuguese business system. It seeks to identify and describe these cultural representations, using an ethnographic methodology and discourse analysis techniques. These representations are then compared with those held by members of a sub-group of the target business community consisting of students of language and business skills . This comparison has the pedagogical objective of producing recommendations for syllabus content

Assessment of Canopy Chlorophyll Content Retrieval in Maize and Soybean: Implications of Hysteresis on the Development of Generic Algorithms

Canopy chlorophyll content (Chl) closely relates to plant photosynthetic capacity, nitrogen status and productivity. The goal of this study is to develop remote sensing techniques for accurate estimation of canopy Chl during the entire growing season without re-parameterization of algorithms for two contrasting crop species, maize and soybean. These two crops represent different biochemical mechanisms of photosynthesis, leaf structure and canopy architecture. The relationships between canopy Chl and reflectance, collected at close range and resampled to bands of the Multi Spectral Instrument (MSI) aboard Sentinel-2, were analyzed in samples taken across the entirety of the growing seasons in three irrigated and rainfed sites located in eastern Nebraska between 2001 and 2005. Crop phenology was a factor strongly influencing the reflectance of both maize and soybean. Substantial hysteresis of the reflectance vs. canopy Chl relationship existed between the vegetative and reproductive stages. The effect of the hysteresis on vegetation indices (VI), applied for canopy Chl estimation, depended on the bands used and their formulation. The hysteresis greatly affected the accuracy of canopy Chl estimation by widely-used VIs with near infrared (NIR) and red reflectance (e.g., normalized difference vegetation index (NDVI), enhanced vegetation index (EVI) and simple ratio (SR)). VIs that use red edge and NIR bands (e.g., red edge chlorophyll index (CIred edge), red edge NDVI and the MERIS terrestrial chlorophyll index (MTCI)) were minimally affected by crop phenology (i.e., they exhibited little hysteresis) and were able to accurately estimate canopy Chl in two crops without algorithm re-parameterization and, thus, were found to be the best candidates for generic algorithms to estimate crop Chl using the surface reflectance products of MSI Sentinel-2