Developing a cross-age teaching programs: the benefits to the student ‘teachers’

Cross‐age teaching is a technique where an older student acts as ‘teacher’ and teaches concepts to younger students. This paper includes a literature review that discusses the benefits of cross‐age teaching to the older ‘teachers,’ and reviews a program developed by the researcher based on the benefits of good cross‐age teaching programs, where 11th grade honors chemistry students create, develop, and assess a science lesson to teach 5th grade science students. The process is detailed, and concludes with the students and teachers reflecting over the results and what changes could be made to improve such a program in the future. Finally, applications of cross‐age teaching programs are explored, and the research concludes the benefits of being the ‘teacher’ are advantageous to all levels of students. Such programs are in need of more collaboration and effort on the part of educators and researchers, but the benefits gained by all students make effort well worth it

Safety issues in PV systems: design choices for a secure fault detection and for preventing fire risk

Photovoltaic systems have played a key role over the last decade in the evolution of the electricity sector. In terms of safety design, it's important to consider that a PV plant constitutes a special system of generation, where the Direct Current (DC) presence results in changes to the technical rules. Moreover, if certain electrical faults occur, the plant is a possible source of fire. Choices regarding the grounding of the generator and its protection devices are fundamental for a design that evaluates fire risk. The subject of the article is the analysis of the relation between electrical phenomena in PV systems and the fire risk related to ensuring appropriate fault detection by the electrical protection system. A description of a grid-connected PV system is followed firstly by a comparison of the design solutions provided by international Standards, and secondly by an analysis of electrical phenomena which may trigger a fire. A study of two existing PV systems, where electrical faults have resulted in fires, is then presented. The study highlights the importance of checking all possible failure modes in a PV system design phase, to assess fire risk in advance. Some guidelines for the mitigation of electrical faults that may result in a fire are finally provided

The roles, needs, and challenges of Arkansas women in agriculture

Participants of the 2005-2007 Arkansas Women in Agriculture conferences were surveyed for this study to identify recent changes in their roles on and off the farm, the factors important to their success, and the problems they face in their businesses. Respondents were broken into two groups—Farm (women owner-operators of farms, ranches, or agribusinesses) and Non-farm (women working in supporting agricultural industries)—for comparisons and responses were also analyzed across years. Farm women most often reported problems keeping good employees each year, while Non-farm women often reported having problems with being respected as a female business person. For Farm women, the factor most often cited as important to success in their business was being able to pass the business on to family; for Non-farm women it was being able to apply their talents and skills. These results suggest that different types of agricultural women hold different attitudes about business and face different challenges. Results across years suggest that successes and problems may change over time. This marks some of the first research on the roles, challenges, and attitudes of Arkansas’ women in agriculture. Based on the results of this research, educational efforts are underway across the state to assist Arkansas’ women in agriculture. However, given the small sample of women surveyed, further research is still needed to fully understand the roles, challenges, and attitudes of Arkansas’ women in agriculture

A Decade of Debt

This book presents evidence that public debts in the advanced economies have surged in recent years to levels not recorded since the end of World War II, surpassing the heights reached during the First World War and the Great Depression. At the same time, private debt levels, particularly those of financial institutions and households, are in uncharted territory and are (in varying degrees) a contingent liability of the public sector in many countries. Historically, high leverage episodes have been associated with slower economic growth and a higher incidence of default or, more generally, restructuring of public and private debts. A more subtle form of debt restructuring in the guise of “financial repression” (which had its heyday during the tightly regulated Bretton Woods system) also importantly facilitated sharper and more rapid debt reduction than would have otherwise been the case from the late 1940s to the 1970s. It is conjectured here that the pressing needs of governments to reduce debt rollover risks and curb rising interest expenditures in light of the substantial debt overhang (combined with the widespread “official aversion” to explicit restructuring) are leading to a revival of financial repression—including more directed lending to government by captive domestic audiences (such as pension funds), explicit or implicit caps on interest rates, and tighter regulation on cross-border capital movements.

Serial Default and the "Paradox" of Rich to Poor Capital Flows

Lucas (1990) argued that it was a paradox that more capital does not flow from rich countries to poor countries. He rejected the standard explanation of expropriation risk and argued that paucity of capital flows to poor countries must instead be rooted in externalities in human capital formation favoring further investment in already capital rich countries. In this paper, we review the various explanations offered for this paradox.' There is no doubt that there are many reasons why capital does not flow from rich to poor nations yet the evidence we present suggests some explanations are more relevant than others. In particular, as long as the odds of non repayment are as high as 65 percent for some low income countries, credit risk seems like a far more compelling reason for the paucity of rich-poor capital flows. The true paradox may not be that too little capital flows from the wealthy to the poor nations, but that too much capital (especially debt) is channeled to debt intolerant serial defaulters.

The Modern History of Exchange Rate Arrangements: A Reinterpretation

We develop a novel system of re-classifying historical exchange rate regimes. One difference between our study and previous classification efforts is that we employ an extensive data base on market-determined parallel exchange rates. Our 'natural' classification algorithm leads to a stark reassessment of the post-war history of exchange rate arrangements. When the official categorization is a form of peg, roughly half the time our classification reveals the true underlying monetary regime to be something radically different, often a variant of a float. Conversely, when official classification is floating, our scheme routinely suggests that the reality was a form of de facto peg. Our new classification scheme points to a complete rethinking of economic performance under alternative exchange rate regimes. Indeed, the breakup of Bretton Woods had a far less dramatic impact on most exchange rate regimes than is popularly believed. Also, contrary to an influential empirical literature, our evidence suggests that exchange rate arraignments may be quite important for growth, trade and inflation. Our newly compiled monthly data set on market-determined exchange rates goes back to 1946 for 153 countries.

Deblocking of interacting particle assemblies: from pinning to jamming

A wide variety of interacting particle assemblies driven by an external force are characterized by a transition between a blocked and a moving phase. The origin of this deblocking transition can be traced back to the presence of either external quenched disorder, or of internal constraints. The first case belongs to the realm of the depinning transition, which, for example, is relevant for flux-lines in type II superconductors and other elastic systems moving in a random medium. The second case is usually included within the so-called jamming scenario observed, for instance, in many glassy materials as well as in plastically deforming crystals. Here we review some aspects of the rich phenomenology observed in interacting particle models. In particular, we discuss front depinning, observed when particles are injected inside a random medium from the boundary, elastic and plastic depinning in particle assemblies driven by external forces, and the rheology of systems close to the jamming transition. We emphasize similarities and differences in these phenomena.Comment: 20 pages, 8 figures, submitted for a special issue of the Brazilian Journal of Physics entitled: Statistical Mechanics of Irreversible Stochastic Models - I