Helium 3/Helium 4 dilution cryocooler for space

Prototype dilution cryocoolers based on dilution refrigeration and adiabatic demagnetization refrigeration (ADR) cycles were designed, constructed, and tested. Although devices the devices did not operate as fully functional dilution cryocoolers, important information was gathered. The porous metal phase separator was demonstrated to operate in the -1-g configuration; this phase separation is the critical element in the He-3 circulation dilution cryocooler. Improvements in instrumentation needed for additional tests and development were identified

Structuring a Wayfinder\u27s Dynamic and Uncertain Environment

Wayfinders typically travel in dynamic environments where barriers and requirements change over time. In many cases, uncertainty exists about the future state of this changing environment. Current geographic information systems lack tools to assist wayfinders in understanding the travel possibilities and path selection options in these dynamic and uncertain settings. The goal of this research is a better understanding of the impact of dynamic and uncertain environments on wayfinding travel possibilities. An integrated spatio-temporal framework, populated with barriers and requirements, models wayfinding scenarios by generating four travel possibility partitions based on the wayfinder\u27s maximum travel speed. Using these partitions, wayfinders select paths to meet scenario requirements. When uncertainty exists, wayfinders often cannot discern the future state of barriers and requirements. The model to address indiscemibility employs a threevalued logic to indicate accessible space, inaccessible space, and possibly inaccessible space. Uncertain scenarios generate up to fifteen distinct travel possibility categories. These fifteen categories generalize into three-valued travel possible partitions based on where travel can occur and where travel is successful. Path selection in these often-complex environments is explored through a specific uncertain scenario that includes a well-defined initial requirement and the possibility of an additional requirement somewhere beforehand. Observations from initial path selection tests with this scenario provide the motivation for the hypothesis that paths arriving as soon as possible to well-defined requirements also maximize the probability of success in meeting possible additional requirements. The hypothesis evaluation occurs within a prototype Travel Possibility Calculator application that employs a set of metrics to test path accessibility in various linear and planar scenarios. The results did not support the hypothesis, but showed instead that path accessibility to possible additional requirements is greatly influenced by the spatio-temporal characteristics of the scenario\u27s barriers

KNOWING AND BEING KNOWN: SEXUAL DELINQUENCY, STARDOM, AND ADOLESCENT GIRLHOOD IN MIDCENTURY AMERICAN FILM

Sexual delinquency marked midcentury cinematic representations of adolescent girls in 1940s, 50, and early 60s. Drawing from the history of adolescence and the context of midcentury female juvenile delinquency, I argue that studios and teen girl stars struggled for decades with publicity, censorship, and social expectations regarding the sexual license of teenage girls. Until the late 1950s, exploitation films and B movies exploited teen sex and pregnancy while mainstream Hollywood ignored those issues, struggling to promote teen girl stars by tightly controlling their private lives but depriving fan magazines of the gossip and scandals that normally fueled the machinery of stardom. The emergence and image of the postwar, sexually autonomous teen girl finally began to see expression in mainstream melodramas of the late 50s, and teen girl stars such as Sandra Dee and Natalie Wood created new, “post-delinquent” star images wherein “good girls” could still be sexually experienced. This new image was a significant departure from the widespread belief that the sexually active teen girl was a fundamentally delinquent threat to the nuclear family, and offered a liberal counterpoint to more conservative teen girl prototypes like Hayley Mills, which continued to have cultural currency

Complex RIA calcium dynamics and its function in navigational behavior

Recently, we have reported novel and complex calcium dynamics in the RIA interneuron, which has been implicated in several navigational behaviors in C. elegans. Here, we review our findings on the compartmentalized and global calcium events in RIA and propose functional consequence as well as potential regulatory mechanisms of these intriguing calcium signals

Electroporation-based methods for in vivo, whole mount and primary culture analysis of zebrafish brain development

BACKGROUND: Electroporation is a technique for the introduction of nucleic acids and other macromolecules into cells. In chick embryos it has been a particularly powerful technique for the spatial and temporal control of gene expression in developmental studies. Electroporation methods have also been reported for Xenopus, zebrafish, and mouse. RESULTS: We present a new protocol for zebrafish brain electroporation. Using a simple set-up with fixed spaced electrodes and microinjection equipment, it is possible to electroporate 50 to 100 embryos in 1 hour with no lethality and consistently high levels of transgene expression in numerous cells. Transfected cells in the zebrafish brain are amenable to in vivo time lapse imaging. Explants containing transfected neurons can be cultured for in vitro analysis. We also present a simple enzymatic method to isolate whole brains from fixed zebrafish for immunocytochemistry. CONCLUSION: Building on previously described methods, we have optimized several parameters to allow for highly efficient unilateral or bilateral transgenesis of a large number of cells in the zebrafish brain. This method is simple and provides consistently high levels of transgenesis for large numbers of embryos

Resource extraction, resistance, and religion in Nicaragua

My dissertation examines the causes of protest over resource extraction in Nicaragua, and underlines the role of religion as a catalyst for sustained and successful challenges against resource extraction. With few exceptions, existing research has rarely explored individual-level attitudes related to resource extraction. Opposition and support towards mining are not mutually exclusive from protest success in overturning a mining concession. They build off each other. If a community strongly opposes mining, especially related to economic threats and grievances tied to environmental and agricultural concerns, it will likely continue its resistance movement until it sees policy changes that halt or overturn mining concessions in the community. However, if there is support for mining in the community over economic opportunities and benefits, mining activities will likely prevail because individuals in the community believe they will economically benefit from mining. I examine the causes of opposition and support over resource extraction in two Nicaraguan mining communities through qualitative interviews and public opinion surveys. I am particularly interested in why individuals either support or oppose resource extraction, and how these attitudes are shaped by social engagement (i.e., formed or reinforced) through participation in various types of local organizations. In doing so, scholars can begin to understand different individual responses to mining that underline the aggregate stories of homogenous community resistance and better understand the individual mechanisms that lead citizens in extractive areas to either partake in mining resistance or abstain. Additionally, existing literature has largely ignored the role of religion as a catalyst in fomenting successful resistance against resource extraction. In fact, there are thousands of protests against resource extraction in Latin America and hundreds throughout Nicaragua, but only a small fraction of them are effective in stopping mining concessions. Because there are clear power imbalances between communities and extractive companies, preventing a new mining project from being implemented or ending an existing project is a very difficult endeavor. Large-scale extractive companies often utilize "divide and rule" strategies that successfully break up local opposition to extraction. My dissertation examines how religion acts as a catalyzing agent in providing communities with the organizational tools and resources that assist individuals in effectively and sustainably to unite and organize against mining until the community achieves a successful national-level policy change reversing mining concessions

Food fortification - a feasible, cost-effective option in the fight against vitamin A deficiency in South Africa

No Abstrac

Democrats and Republicans Can Be Differentiated from Their Faces

Background: Individuals ’ faces communicate a great deal of information about them. Although some of this information tends to be perceptually obvious (such as race and sex), much of it is perceptually ambiguous, without clear or obvious visual cues. Methodology/Principal Findings: Here we found that individuals ’ political affiliations could be accurately discerned from their faces. In Study 1, perceivers were able to accurately distinguish whether U.S. Senate candidates were either Democrats or Republicans based on photos of their faces. Study 2 showed that these effects extended to Democrat and Republican college students, based on their senior yearbook photos. Study 3 then showed that these judgments were related to differences in perceived traits among the Democrat and Republican faces. Republicans were perceived as more powerful than Democrats. Moreover, as individual targets were perceived to be more powerful, they were more likely to be perceived as Republicans by others. Similarly, as individual targets were perceived to be warmer, they were more likely to be perceived as Democrats. Conclusions/Significance: These data suggest that perceivers ’ beliefs about who is a Democrat and Republican may be based on perceptions of traits stereotypically associated with the two political parties and that, indeed, the guidance of these stereotypes may lead to categorizations of others ’ political affiliations at rates significantly more accurate than chanc

Temporal and Spatial Requirements of unplugged/MuSK Function during Zebrafish Neuromuscular Development

One of the earliest events in neuromuscular junction (NMJ) development is the accumulation of acetylcholine receptor (AChR) at the center of muscle cells. The unplugged/MuSK (muscle specific tyrosine kinase) gene is essential to initiate AChR clustering but also to restrict approaching growth cones to the muscle center, thereby coordinating pre- and postsynaptic development. To determine how unplugged/MuSK signaling coordinates these two processes, we examined the temporal and spatial requirements of unplugged/MuSK in zebrafish embryos using heat-shock inducible transgenes. Here, we show that despite its expression in muscle cells from the time they differentiate, unplugged/MuSK activity is first required just prior to the appearance of AChR clusters to simultaneously induce AChR accumulation and to guide motor axons. Furthermore, we demonstrate that ectopic expression of unplugged/MuSK throughout the muscle membrane results in wildtype-like AChR prepattern and neuromuscular synapses in the central region of muscle cells. We propose that AChR prepatterning and axonal guidance are spatio-temporally coordinated through common unplugged/MuSK signals, and that additional factor(s) restrict unplugged/MuSK signaling to a central muscle zone critical for establishing mid-muscle synaptogenesis