A study of the Earth return aerocapture for a manned Mars mission

The current architecture being considered by NASA for a future manned Mars mission involves the use of an aerocapture procedure at both Mars and Earth arrival. The aerocapture will be used to decelerate and insert the vehicles into the desired orbits at the respective planets. The crew may return to Earth in a large, inflatable habitat known as the Transhab. This Transhab would be complimented with an aeroshell, which will serve the dual purposes of providing protection from the intense heat of high-speed atmospheric flight and offer some lifting ability to the vehicle as well. The aeroshell has been dubbed the Ellipsled because of the characteristic shape. This thesis represents a preliminary study of the aerocapture of the Transhab/Ellipsled vehicle upon Earth return. Undershoot and overshoot boundaries have been examined as a function of entry velocity for a variety of constraining factors such as deceleration limits and vehicle ballistic coefficient. The effects of atmospheric dispersions have also been explored. In addition, a simple 180 degree roll maneuver has been implemented in the undershoot trajectories to help target the desired 407 km circular Earth orbit. Results show that the Transhab/Ellipsled vehicle has a nominal entry corridor width of 0.5 - 0.7 degrees for entry speeds ranging from 12.5 km/s to 14.5 km/s. In addition, entry corridor comparisons have been made between the Transhab/Ellipsled and a modified Apollo capsule which is also being considered for the Earth return vehicle. Future studies should focus on refining the heating rate analyses, off-nominal vehicle aerodynamics, winds, horizontal density waves, and changes in the vehicle trim angle of attack. Furthermore, a guidance algorithm should be implemented to optimize the overall trajectory and minimize inclination changes and post-aerocapture delta V needed to circularize the orbit

Plurality, Narratives, and Politics: What Hannah Arendt can Offer Critical Literacy Theory

In recent years, scholars, journalists, and citizens have turned to Hannah Arendt’s writings to make sense of human plurality and resist right-wing nationalist movements around the globe. This article discusses Arendt’s ideas of plurality, narratives, and politics and describes how these ideas can help critical literacy theory focus on both social groups and unique persons. For Arendt, the human world is a world of plurality because it includes not only diverse social groups, but also human selves living unique versions of group lives. This latter kind of plurality is difficult to see in some approaches to critical literacy. Arendt argues the plurality of unique persons becomes visible when people tell life narratives in particular ways. Given this view of plurality and narratives, the political question of who counts as members of a public is, in part, a question of whose stories are told. Arendt insists this is not only a question of a person telling her own story; it is also a question of a person hearing her story told by others. These arguments can add new dimensions to critical literacy’s view of diversity and the politics of reading, writing, speaking, thinking, and listening

Visual Arts and Literacy: The Potential of Interdisciplinary Coalitions for Social Justice

In this article, we explore the possibilities of creating a coalition of the visual arts with literacy to work toward meaningful integrated learning experiences with a social justice agenda. We discuss the benefits of integrated curriculum and its potential to support learning at many levels. Following that, we introduce the Hope House mural project as an example of an integrated visual arts and literacy program. Through this project, children and their incarcerated fathers grapple with significant issues in their lives and to build a bond while doing so. We argue that this coalition results in learning that is inseparably tied to the technical and the profound, thanks to the synergy of the art and literacy experience

Reading Strategies for Middle and High School Students: A Review of Literature

This review targets “best practices” in adolescent reading instruction. While writing is inextricably related to reading, this review did not explicitly target studies of writing. However, where writing studies informed reading instruction, they were cited in this review. The first step in this search for empirical data was the U.S. Department of Education, Institute of Education Science’s What Works Clearinghouse. From the reports listed there, I followed major references to identify other key and current publications that targeted educators and stakeholders at the classroom, school, system, and state levels. Though its findings are still emerging and we are still learning how to apply them to the “real world” of practice, the field of adolescent literacy research has produced an impressive volume of empirical and theoretical scholarship over the past decade. Due to time constraints, rather than attempt to review primary sources, I relied on the following 17 syntheses of studies. Collectively they summarize the findings from 37 experimental and quasi experimental studies (kamil et al., 2008) as well as hundreds of correlation studies and theoretical papers

Language Works 7(1)

Welcome to the 12th issue of Language Works. After two years (has it really ”only” been two years?) in the shadow of Covid, we are now back to studies and research as we know it. This also means a new issue of Language Works, which this time around is bursting at the seams with a total of five articles that span across the broad field of linguistics. Welcome, and happy reading!Velkommen til den 12. udgave af Language Works. Efter to år (er det virkelig ”kun” to år?) i skyggen af covid er vi tilbage til studier og forskning som vi kender det. Det betyder også et nyt nummer af Language Works der denne gang flyder over med hele fem artikler der kommer bredt omkring i det sprogvidenskabelige felt. Velkommen til og god læsning

Leptin is a four-helix bundle: secondary structure by NMR

AbstractLeptin is a signaling protein that in its mutant forms has been associated with obesity and Type II diabetes. The lack of sequence similarity has precluded analogies based on structural resemblance to known systems. Backbone NMR signals for mouse leptin (13C/15N -labeled) have been assigned and its secondary structure reveals it to be a four-helix bundle cytokine. Helix lengths and disulfide pattern are in agreement with leptin as a member of the short-helix cytokine family. A three-dimensional model was built verifying the mechanical consistency of the identified elements with a short-helix cytokine core

Language Works 7(1)

Welcome to the 12th issue of Language Works. After two years (has it really ”only” been two years?) in the shadow of Covid, we are now back to studies and research as we know it. This also means a new issue of Language Works, which this time around is bursting at the seams with a total of five articles that span across the broad field of linguistics. Welcome, and happy reading!Velkommen til den 12. udgave af Language Works. Efter to år (er det virkelig ”kun” to år?) i skyggen af covid er vi tilbage til studier og forskning som vi kender det. Det betyder også et nyt nummer af Language Works der denne gang flyder over med hele fem artikler der kommer bredt omkring i det sprogvidenskabelige felt. Velkommen til og god læsning

Comparison of Sexual Mixing Patterns for Syphilis in Endemic and Outbreak Settings

In a largely rural region of North Carolina during 1998–2002, outbreaks occurred of heterosexually-transmitted syphilis, tied to crack cocaine use and exchange of sex for drugs and money. Sexual partnership mixing patterns are an important characteristic of sexual networks that relate to transmission dynamics of STIs

Estimating the Holdout Problem in Land Assembly

The Supreme Court's recent decision in Kelo v. New London allows the use of eminent domain to facilitate private economic development. While the court's condition for allowing takings was highly expansive, there may be a market failure that warrants state intervention when parcels of land need to be combined for redevelopment. The collective action or strategic holdout problem associated with land assembly may limit redevelopment of older communities when one or more existing owners seek to capture a disproportionate share of the potential surplus. The problem may be compounded by landowners' uncertainty as to the true value of the expected surplus to be divided (Eckart, 1985; Strange, 1995). At the same time, developers may attempt to disguise the assemblage through the use of straw purchasers. This paper employs administrative Geographic Information System and assessor data from Seattle, Washington, to identify lots that were ultimately assembled. The paper then matches them to their pre-assembly sales. Controlling for lot and existing structure characteristics and census tract-year fixed effects, I find that land bought in the process of a successful assembly commands an 18 percent premium. Consistent with theory, this premium falls with a parcel's relative size in the assemblage. I also find some evidence that parcels toward the center of the development may command a larger premium than those at the edge, suggesting that developers retain or are perceived to retain some design flexibility