Evidence for glaciation in Elysium

It is suggested that certain landforms in the Elysium region of Mars provide strong evidence for glaciation. Landscapes related to subglacial volcanism suggest that ice was a primary agent in the development of Elysium

Evolution of antigen binding receptors

This review addresses issues related to the evolution of the complex multigene families of antigen binding receptors that function in adaptive immunity. Advances in molecular genetic technology now permit the study of immunoglobulin (Ig) and T cell receptor (TCR) genes in many species that are not commonly studied yet represent critical branch points in vertebrate phylogeny. Both Ig and TCR genes have been defined in most of the major lineages of jawed vertebrates, including the cartilaginous fishes, which represent the most phylogenetically divergent jawed vertebrate group relative to the mammals. Ig genes in cartilaginous fish are encoded by multiple individual loci that each contain rearranging segmental elements and constant regions. In some loci, segmental elements are joined in the germline, i.e. they do not undergo genetic rearrangement. Other major differences in Ig gene organization and the mechanisms of somatic diversification have occurred throughout vertebrate evolution. However, relating these changes to adaptive immune function in lower vertebrates is challenging. TCR genes exhibit greater sequence diversity in individual segmental elements than is found in Ig genes but have undergone fewer changes in gene organization, isotype diversity, and mechanisms of diversification. As of yet, homologous forms of antigen binding receptors have not been identified in jawless vertebrates; however, acquisition of large amounts of structural data for the antigen binding receptors that are found in a variety of jawed vertebrates has defined shared characteristics that provide unique insight into the distant origins of the rearranging gene systems and their relationships to both adaptive and innate recognition processes

Public School Choice and Desegregation in Arkansas

Public school choice is an umbrella term for policies that allow students to enroll in a public school other than their residentially-assigned school. Public school choice, also called openenrollment, is typically divided into two categories: intra-district choice, transfers to schools in the same district, and inter-district choice, transfers to schools in other districts

Profitable Prudence: The Case for Public Employer Defined Benefit Plans

Defined benefit plans remain the predominant form of retirement benefit for employees of state and local governments in the United States, which employ more than 10 percent of the nation’s workforce. This chapter describes the divergence between pensions in private industry, where the focus has shifted sharply toward defined contribution plans, and in the public sector, where defined benefit plans continue to dominate. One reason is that public employers have the ongoing responsibility of attracting and retaining a large workforce whose diversity is unmatched in private industry. We also offer an economic analysis of public plans, focusing on the value-added to state economies from investment returns which are often superior to those generated by defined contribution plans

Discipline Disproportionalities in Schools: The Relationship between Student Characteristics and School Disciplinary Outcomes

According to a 2014 report from the US Department of Education’s Office for Civil Rights, black students represent only 15% of students across the nation, but 35% of students suspended once are black, 44% of students suspended more than once are black, and 36% of expelled students are black. These disparate disciplinary aggregate outcomes, while troubling, do not provide as much information as policymakers need. In this study, we exploit three years of student-level discipline data from Arkansas to assess the extent to which black students or other minority students were more likely to receive certain types of punishments, even for the same infraction. In previous studies utilizing the same dataset, we find that, consistent with the recent reports on this topic, black students were punished more frequently; furthermore, we find that black students received slightly longer punishments than their white peers in the same school. The current study utilizes multinomial logit to assess the extent to which student demographics predict consequence type, even after controlling for infraction-level information and district characteristics. Black students, males, and low-income students (eligible for free- and reduced- lunch) were more likely to receive certain types of exclusionary consequences such as out-of-school suspension, expulsion, and referrals to Alternative Learning Environments relative to in-school-suspension

Disparate Use of Exclusionary Discipline: Evidence on Inequities in School Discipline from a U.S. State

There is much discussion in the United States about exclusionary discipline (suspensions and expulsions) in schools. According to a 2014 report from the US Department of Education’s Office for Civil Rights, Black students represent 15% of students, but 44% of students suspended more than once, and 36% of expelled students. This analysis uses seven years of individual infraction-level data from public schools in Arkansas. We examine whether disproportionalities exist within schools, or are instead, a function of the type of school attended. We find that marginalized students are more likely to receive exclusionary discipline, even after controlling for the nature and number of disciplinary referrals, but that most of the differences occur across schools rather than within schools

Do School Discipline Policies Treat Students Fairly? A Second Look at School Discipline Rate Disparities

Much work has documented that African-American students are more likely to receive expulsions and suspensions than their white peers. These disparities are troubling, but researchers and policymakers need more information to fully understand this issue. We use three years of student level discipline data for an entire state to assess whether non-white students are receiving different disciplinary consequences from their white peers in the same schools, for similar infractions and with similar behavioral history. We find that Black students received more severe (longer) punishments than their White peers in the state for the same types of infractions. These differences are due primarily to school-level differences, but even within the same schools, Black students receive slightly longer punishments than their White peers

Demonstration project in low-cost shoreline erosion control : final report to County Administrator, County of Accomack, Virginia

·1ow cost erosion control structures were installed at ten shoreline sites located in the lower Chesapeake Bay and on the Potomac and Rappahannock Rivers to further test the applicability of the perched beach concept under diverse littoral environments. The perched beach is achieved via installation of a low sill parallel to the shoreline. The objective of the sill is to provide a partial barrier behind which an elevated (perched) beach is accreted. When successful, ~he perched beach backshore and foreshore acts to reduce the frequency of direct wave attack against the fastland and thereby reducing the erosion rate. In this study, sills were used in conjunction with existing groins as well as alone. Some testing was performed on the use of a spur with existing groins as a device to prevent the formation of a downdrift erosion notch where the groin intersects the fastland. The sills were formed with a series of large PVC-coated nylon bags hydraulically filled with sand or with stone filled gabions. In one case compacted used auto tires were utilized as fill for a gabion. Evaluation of the response to the structures was based upon a series of surveyed beach profiles at each site and sequential photography. At each site the beach profiles were surveyed for several months prior to and following the installation of the various structures. Additional profiles were run adjacent to the treated areas. The structures were emplaced between late March and early June of 1978

Evaluation of a Full-Depth Asphaltic Concrete Pavement

This study was initiated to verify a newly-developed set of design curves for full-depth asphaltic concrete pavements. Quality control during construction was checked using nuclear density testers, Benkelman beams, and a Road Rater. During the course of this study, an analysis system (predicated upon the elastic theory model) was developed to interpret the dynamic deflections as measured by the Road Rater. The thickness design curves were verified by elastic theory and deflection testing within the accuracy of construction variations. Measured rut depths were analyzed in terms of potential rut depth resulting from consolidation under traffic due to lack of obtaining 100-percent of Marshall density during compaction. Traffic was monitored using automatic traffic counters, manual classification/volume counts, and weigh-in-motion scales installed in the pavement

Breaking and Seating of Rigid Pavements

Breaking and seating has been utilized extensively in Kentucky to rehabilitate portland cement concrete pavements. Experience over three or four years with this type of design and construction are summarized and reported. Breaking to a range of nominal fragments is evaluated. Evaluation of two roller weights for seating is reported. The use of dynamic deflections to evaluate the effectiveness of the breaking and seating process and to measure the appropriateness of the asphaltic concrete overlay