The effect of vitamin C deficiency and chronic ultraviolet-B exposure on corneal ultrastructure: a preliminary investigation

Purpose: In the visually debilitating condition of climatic droplet keratopathy, corneal transparency is progressively lost. Although the precise cause of the disease and the mechanism by which it progresses are not known, a lifetime exposure to high solar radiation and a vitamin C–deficient diet may be involved in its development. This study examines the effect of dietary ascorbate levels and ultraviolet (UV)-B exposure on corneal stromal structure. Methods: Eight guinea pigs were divided into four treatment groups (A, B, C, and D). For 15 weeks, Groups A and C were fed an ascorbate-rich diet (2 mg/100 g bodyweight/day), while Groups B and D received an ascorbate-deficient diet (0.07 mg/100 g bodyweight/day). For the last 12 weeks of the study, Groups C and D also experienced chronic UVB exposure (0.12 J/cm2 for 40 min/day). Following euthanasia, the corneas were enucleated and their stromal ultrastructure examined using X-ray scattering and electron microscopy. Results: UVB exposure resulted in an increased corneal thickness (p<0.001), but this was not accompanied by a widespread expansion of the collagen fibrillar array, and in the case of ascorbate-deficient animals, stromal thickening was associated with the compaction of collagen fibrils (p<0.01). Neither UVB exposure nor ascorbic acid deficiency caused any change in the average diameter or D-periodicity of the stromal collagen fibrils. Conclusions: UVB-induced changes in the corneal ultrastructure were most pronounced in animals fed an ascorbic acid–deficient diet. This suggests that ascorbic acid may play a vital role in protecting the corneal stroma from the harmful effects of UVB

Abc Problem In Elementary Mathematics Education: Arithmetic Before Comprehension

Mathematical habits of prospective teachers affect problem comprehension and success and expose their beliefs about mathematics. Prospective elementary teachers (PSTs) (n = 121) engaged in a problem solving activity each week in class. Data were collected from PSTs enrolled in an undergraduate elementary mathematics methods course at a Southeastern State University over multiple semesters (six semesters, seven classes). PSTs’ solution methods for one intentionally misleading mathematics problem were analyzed using a convergent parallel mixed methods content analysis. Two-thirds of PSTs misunderstood the problem scenario and directly translated numbers from the problem text. PSTs who answered correctly used a problem model strategy to comprehend the scenario and were more likely to use multiple models, draw a diagram, and draw a diagram before using another model. However, a large number of PSTs who answered incorrectly also used multiple models and drew diagrams. Self-correction was not common (8 of 121), because their equations did not provide feedback or support comprehension. Three kinds of imprecision also affected problem comprehension and were evident in both correct and incorrect solutions. Intentionally misleading problems helped PSTs see consequences of their mathematical habits and highlighted the importance of sense making and precision when creating problem models

Leaping from discrete to continuous independent variables: Sixth graders’ science line graph interpretations

Students often struggle to interpret graphs correctly, despite emphasis on graphic literacy in U.S. education standards documents. The purpose of this study was to describe challenges sixth graders with varying levels of science and mathematics achievement encounter when transitioning from interpreting graphs having discrete independent variables to graphs having continuous independent variables. Data included think-aloud interviews and written line graph interactions. Data analysis focused on three constituent processes of graph interpretation: (1) encoding salient structures, (2) relating salient structures to each other, and (3) understanding referents in relation to salient structures. Difficulties encoding individual data points influenced interpretations of referents and relationships among data points. Cognitive resources learned for interpreting graphs with discrete independent variables both supported and hindered interpretations of graphs with continuous independent variables. Struggles relating graphs to referents reflected inexperience with data collection and analysis. Recommendations are provided to support students during this transition and to improve their ability to answer different types of graph questions

Leaping From Discrete To Continuous Independent Variables: Sixth Graders’ Science Line Graph Interpretations

Students often struggle to interpret graphs correctly, despite emphasis on graphic literacy in U.S. education standards documents. The purpose of this study was to describe challenges sixth graders with varying levels of science and mathematics achievement encounter when transitioning from interpreting graphs having discrete independent variables to graphs having continuous independent variables. Data included think-aloud interviews and written line graph interactions. Data analysis focused on three constituent processes of graph interpretation: (1) encoding salient structures, (2) relating salient structures to each other, and (3) understanding referents in relation to salient structures. Difficulties encoding individual data points influenced interpretations of referents and relationships among data points. Cognitive resources learned for interpreting graphs with discrete independent variables both supported and hindered interpretations of graphs with continuous independent variables. Struggles relating graphs to referents reflected inexperience with data collection and analysis. Recommendations are provided to support students during this transition and to improve their ability to answer different types of graph questions

ABC problem in elementary mathematics education: Arithmetic before comprehension

Mathematical habits of prospective teachers affect problem comprehension and success and expose their beliefs about mathematics. Prospective elementary teachers (PSTs) (n = 121) engaged in a problem solving activity each week in class. Data were collected from PSTs enrolled in an undergraduate elementary mathematics methods course at a Southeastern State University over multiple semesters (six semesters, seven classes). PSTs’ solution methods for one intentionally misleading mathematics problem were analyzed using a convergent parallel mixed methods content analysis. Two-thirds of PSTs misunderstood the problem scenario and directly translated numbers from the problem text. PSTs who answered correctly used a problem model strategy to comprehend the scenario and were more likely to use multiple models, draw a diagram, and draw a diagram before using another model. However, a large number of PSTs who answered incorrectly also used multiple models and drew diagrams. Self-correction was not common (8 of 121), because their equations did not provide feedback or support comprehension. Three kinds of imprecision also affected problem comprehension and were evident in both correct and incorrect solutions. Intentionally misleading problems helped PSTs see consequences of their mathematical habits and highlighted the importance of sense making and precision when creating problem models

Teacher Educators As Belief-And-Attitude Therapists: Exploring Psychodynamic Implications Of An Emerging Role

Over the past several decades student-teachers have increasingly become the objects of psychological study, especially through cognitive, constructivist and psychoana lytic lenses. This research has been used, in turn, to focus teacher education on changing the beliefs and attitudes of student-teachers in order to foster new teaching practices. In this way, teacher educators are becoming \u27belief-and-attitude therapists\u27, a role that few have trained for or thoroughly understand. In this paper I examine the psychodynamic relationships between teacher educators and student-teachers, using Vaillant\u27s taxonomy of ego defences. I illustrate selected examples of these ego defences from my work with teacher educators before exploring the social contexts of teacher education that foster these dynamics. Central to this examination is a double-bind between teacher educators\u27 desire to reform schooling through pre-service teacher education, and the need to develop the professional competence of student-teachers. Finally, I adapt the notion of psychotherapeu tic neutrality as a way of helping teacher educators understand these dynamics in their practice. This line of inquiry begs for more research on the communicative dynamics between teacher educators and student-teachers, and how these are affected by institutional cultures. © 2003 Taylor & Francis Ltd

Boote, David N., Teachers\u27 Professional Discretion and the Curricula, Teachers and Teaching, 12(August,2006), 461-478.*

Posits three developmental levels of teachers\u27 professional discretion (procedural, substantive, innovative) in making teaching and curriculum decisions and describes the appropriate kinds of professional development required for teachers to move to the highest of these levels of professional discretion; discusses changes in curriculum policies and institutional practices and culture needed to acknowledge and foster teachers\u27 development of innovative professional discretion

An "Indoctrination Dilemma" in Teacher Education?

Most contemporary research in teacher education is focused on theories and methods of changing student teachers' beliefs, values , and practices . Unfortunately, researchers and practitioners have paid little attention to the ethical questions surrounding belief change. To stimulate dialogue in this area, this paper contrasts teacher educators desires to change student teachers' beliefs and values with their need to foster professional autonomy. While most teacher educators justify their practices on their good intentions, superior pedagogy , or the importance of their beliefs , enabling student teachers to gain critical competence during their preservice education is arguably just as important. For a variety of epistemological, sociological, and psychological reasons, doing both simultaneously is almost always impossible. This conclusion suggests an unrecognized 'indoctrination dilemma' inherent in preservice teacher education. The paper concludes by suggesting that teacher educators perhaps need to r e-examine their intention

Learning From The Literature: Some Pedagogies

Daily headlines underscore the challenges managers face in creating and sustaining ethical organizations. Accounts of scandals at companies like AIG, Goldman Sachs, Countrywide Financial, and Lehman Brothers appear alongside equally troubling stories of misdeeds in political, religious, and not-for-pro t settings. Ethics researchers have explored both individual and organizational in uences on ethics, and this research has increased our understanding of ethical behavior in organizations. is chapter seeks to expand our knowledge even further by considering not just the individual and the organization, but the relationship between the two-the employee-organization relationship (EOR)-as an important factor in determining ethical outcomes. In addition, it seeks to enhance our understanding of the EOR by demonstrating how organizational ethics research might inform our thinking about the EOR. In particular, it describes the role that organizational ethics play in creating a powerful contextual in uence, providing both opportunities and constraints on the multiple connections that exist between employees and their organizations