SOME ISSUES CONCERNING SPECIFICATION AND INTERPRETATION OF OUTDOOR RECREATION DEMAND MODELS

Resource /Energy Economics and Policy,

Teacher Effects on Academic and Social Outcomes in Elementary School

Numerous studies conclude that teacher effects on academic achievement are substantial in size. Education is about more than academic achievement, and we know very little about teachers' effectiveness in promoting students' social development. Using data from the Early Childhood Longitudinal Study-Kindergarten Cohort (ECLS- K), we estimate teacher effects on social as well as academic outcomes. We find that teacher effects on social development are sizeable, and are approximately twice as large as teacher effects on academic development. We further determine that teachers who produce better than average academic results are not the same teachers who produce better than average social results. However, we find that observable characteristics of teachers and the instructional approaches utilized in their classrooms are weak predictors of teacher effects. Finally, we show that the development of social skills has a positive effect on the growth of academic skills, and therefore teachers who are good at teaching social skills provide an additional indirect boost to academic skills in addition to their direct teaching of academic skills. We conclude that current policy debates over what it means to be a "highly qualified teacher" should also take social development into account

Teacher effects on social/behavioral skills in early elementary school

Though many recognize that social and behavioral skills play an important role in educational stratification, no studies have attempted to estimate teachers’ effects on these outcomes. Using data from the Early Childhood Longitudinal Study–Kindergarten Cohort (ECLS–K), we estimate teacher effects on social and behavioral skills as well as on academic achievement. Teacher effects on social and behavioral skill development are sizeable, and are somewhat larger than teacher effects on academic development. Because—as we show—social and behavioral skills have a positive effect on the growth of academic skills in the early elementary grades, the teachers who are good at enhancing social and behavioral skills provide an additional indirect boost to academic skills in addition to their direct teaching of academic skills. Like previous studies we find that observable characteristics of teachers and the instructional approaches utilized in their classrooms are weak predictors of teacher effects. However, our results suggest that the teachers who produce better than average academic results are not always the same teachers who excel in enhancing social and behavioral skills

Social/behavioral skills and the gender gap in early educational achievement

Though many studies have suggested that social and behavioral skills play a central role in gender stratification processes, we know little about the extent to which these skills affect gender gaps in academic achievement. Analyzing data from the Early Child Longitudinal Study-Kindergarten Cohort, we demonstrate that social and behavioral skills have substantively important effects on academic outcomes from kindergarten through fifth grade. Gender differences in the acquisition of these skills, moreover, explain a considerable fraction of the gender gap in academic outcomes during early elementary school. Boys get roughly the same academic return to social and behavioral skills as their female peers, but girls retain an advantage both because they begin school with more advanced social and behavioral skills, and because their skill advantage grows over time. While part of the effect may reflect an evaluation process that rewards students who better conform to school norms, our results imply that the acquisition of social and behavioral skills enhances learning as well. Our results call for a reconsideration of the family and school-level processes that produce gender gaps in social/behavioral skills and the advantages they confer for academic and later success

Structural identifiability of equivalent circuit models for Li-Ion batteries

Structural identifiability is a critical aspect of modelling that has been overlooked in the vast majority of Li-ion battery modelling studies. It considers whether it is possible to obtain a unique solution for the unknown model parameters from experimental data. This is a fundamental prerequisite of the modelling process, especially when the parameters represent physical battery attributes and the proposed model is utilised to estimate them. Numerical estimates for unidentifiable parameters are effectively meaningless since unidentifiable parameters have an infinite number of possible numerical solutions. It is demonstrated that the physical phenomena assignment to a two-RC (resistor–capacitor) network equivalent circuit model (ECM) is not possible without additional information. Established methods to ascertain structural identifiability are applied to 12 ECMs covering the majority of model templates used previously. Seven ECMs are shown not to be uniquely identifiable, reducing the confidence in the accuracy of the parameter values obtained and highlighting the relevance of structural identifiability even for relatively simple models. Suggestions are proposed to make the models identifiable and, therefore, more valuable in battery management system applications. The detailed analyses illustrate the importance of structural identifiability prior to performing parameter estimation experiments, and the algebraic complications encountered even for simple models. View Full-Tex

Brachial vein transposition arteriovenous fistulas for hemodialysis access

BackgroundAn arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis, offering lower morbidity, mortality, and cost compared with grafts or catheters. Patients with a difficult access extremity have often lost all superficial veins, and even basilic veins may be obliterated. We have used brachial vein transposition AVFs (BVT-AVFs) in these challenging patients and review our experience in this report.MethodsThe study reviewed consecutive patients in whom BVT-AVFs were created from September 2006 to March 2009. Most BVT-AVFs were created in staged procedures, with the second-stage transposition operations completed 4 to 6 weeks after the first-stage AVF operation. A single-stage BVT-AVF was created when the brachial vein diameter was ≥6 mm.ResultsWe identified 58 BVT-AVF procedures, comprising 41 women (71.0%), 28 diabetic patients (48.3%), and 29 (50.0%) had previous access surgery. The operation was completed in two stages in 45 operations (77.6%) and was a primary transposition in 13 patients. However, five of these were secondary AVFs with previous distal AV grafts or AVFs placed elsewhere; effectively, late staged procedures. Follow-up was a mean of 11 months (range, 2.0-31.7 months). Primary patency, primary-assisted patency, and cumulative (secondary) patency were 52.0%, 84.9%, and 92.4% at 12 months and 46.2%, 75.5%, and 92.4% at 24 months, respectively. Harvesting the brachial vein was tedious and more difficult than harvesting other superficial veins. No prosthetic grafts were used.ConclusionBVT-AVFs provide a suitable option for autogenous access when the basilic vein is absent in patients with difficult access extremities. Most patients required intervention for access maturation or maintenance. Most BVT-AVFs were created with staged procedures. Cumulative (secondary) patency was 92.4% at 24 months

Brachial vein transposition arteriovenous fistulas for hemodialysis access

BackgroundAn arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis, offering lower morbidity, mortality, and cost compared with grafts or catheters. Patients with a difficult access extremity have often lost all superficial veins, and even basilic veins may be obliterated. We have used brachial vein transposition AVFs (BVT-AVFs) in these challenging patients and review our experience in this report.MethodsThe study reviewed consecutive patients in whom BVT-AVFs were created from September 2006 to March 2009. Most BVT-AVFs were created in staged procedures, with the second-stage transposition operations completed 4 to 6 weeks after the first-stage AVF operation. A single-stage BVT-AVF was created when the brachial vein diameter was ≥6 mm.ResultsWe identified 58 BVT-AVF procedures, comprising 41 women (71.0%), 28 diabetic patients (48.3%), and 29 (50.0%) had previous access surgery. The operation was completed in two stages in 45 operations (77.6%) and was a primary transposition in 13 patients. However, five of these were secondary AVFs with previous distal AV grafts or AVFs placed elsewhere; effectively, late staged procedures. Follow-up was a mean of 11 months (range, 2.0-31.7 months). Primary patency, primary-assisted patency, and cumulative (secondary) patency were 52.0%, 84.9%, and 92.4% at 12 months and 46.2%, 75.5%, and 92.4% at 24 months, respectively. Harvesting the brachial vein was tedious and more difficult than harvesting other superficial veins. No prosthetic grafts were used.ConclusionBVT-AVFs provide a suitable option for autogenous access when the basilic vein is absent in patients with difficult access extremities. Most patients required intervention for access maturation or maintenance. Most BVT-AVFs were created with staged procedures. Cumulative (secondary) patency was 92.4% at 24 months

Policy challenges from the "White" Senate inquiry into workplace-related health impacts of toxic dusts and nanoparticles

On 22 June 2005 the Senate of the Commonwealth of Australia voted to establish an inquiry into workplace harm related to toxic dust and emerging technologies (including nanoparticles). The inquiry became known as the "White" Inquiry after Mr Richard White, a financially uncompensated sufferer of industrial sandblasting-induced lung disease who was instrumental in its establishment. The "White" Inquiry delivered its final report and recommendations on 31 May 2006. This paper examines whether these recommendations and their implementation may provide a unique opportunity not only to modernize relevant monitoring standards and processes, but related compensation systems for disease associated with workplace-related exposure to toxic dusts. It critically analyzes the likely role of the new Australian Safety and Compensation Council (ASCC) in this area. It also considers whether recommendations related to potential workplace related harm from exposure to nanoparticles could commence a major shift in Australian healthcare regulation

Quark-Meson Coupling Model for a Nucleon

The quark-meson coupling model for a nucleon is considered. The model describes a nucleon as an MIT bag, in which quarks are coupled to scalar and vector mesons. A set of coupled equations for the quark and the meson fields are obtained and are solved in a self-consistent way. It is shown that the mass of a nucleon as a dressed MIT bag interacting with sigma- and omega-meson fields significantly differs from the mass of a free MIT bag. A few sets of model parameters are obtained so that the mass of a dressed MIT bag becomes the nucleon mass. The results of our calculations imply that the self-energy of the bag in the quark-meson coupling model is significant and needs to be considered in doing the nuclear matter calculations.Comment: 3 figure