A Novel Neutron Recoil Spectrometer Concept Utilizing Heavy-Ion Recoils and Time- and Spatially-Resolved Sensor

This thesis describes a heavy-ion recoil neutron spectrometer as an alternative to existing magnetic proton recoil neutron spectrometers for inertial confinement fusion experiments. Whereas existing designs elastically scatter neutrons o↵ protons or deuterons, which are then magnetically analyzed to infer energy, this device works by elastically scattering neutrons in a nanometer-scale film of a higher-Z material. The resulting heavy ions are then measured on a time- and space-resolved semiconductor detector. Using this time and location information, coupled with the equations governing the mechanics of elastic collisions, one can determine the energy of the neutron that scattered the ion. This thesis considers the many influential design factors, including cross sections, ion straggling, timing, and foil and sensor geometries with respect to the resulting viability and performance. Finally, two reference designs are presented for comparison with the magnetic proton recoil neutron spectrometer currently fielded at the National Ignition Facility. For a monoenergetic 14-MeV neutron source, the minimum achieved full-width-at-half-maximum is 0.33 MeV, compared with 0.69 MeV for the currently fielded detector. The maximum e ciency is found to be 2.94x10 10, compared with a current maximum of 8.48x10 11

STY1 and STY2 promote the formation of apical tissues during Arabidopsis gynoecium development

Gynoecium ontogenesis in Arabidopsis is accomplished by the co-ordinated activity of genes that control patterning and the regional differentiation of tissues, and ultimately results in the formation of a basal ovary, a short style and an apical stigma. A transposon insertion in the STYLISH1 (STY1) gene results in gynoecia with aberrant style morphology, while an insertion mutation in the closely related STYLISH2 (STY2) gene has no visible effect on gynoecium development. However, sty1-1 sty2-1 double mutant plants exhibit an enhanced sty1-1 mutant phenotype and are characterized by a further reduction in the amount of stylar and stigmatic tissues and decreased proliferation of stylar xylem. These data imply that STY1 and STY2 are partially redundant and that both genes promote style and stigma formation and influence vascular development during Arabidopsis gynoecium development. Consistently, STY1 and STY2 are expressed in the apical parts of the developing gynoecium and ectopic expression of either STY1 or STY2 driven by the CaMV 35S promoter is sufficient to transform valve cells into style cells. STY1::GUS and STY2::GUS activity is detected in many other organs as well as the gynoecium, suggesting that STY1 and STY2 may have additional functions. This is supported by the sty1-1 sty2-1 double mutants producing rosette and cauline leaves with a higher degree of serration than wild-type leaves. STY1 and STY2 are members of a small gene family, and encode proteins with a RING finger-like motif. Double mutant analyses indicate that STY1 genetically interacts with SPATULA and possibly also with CRABS CLAW

Conversations about Diversity: Institutional Barriers for Underrepresented Engineering Students

The United States is becoming increasingly more diverse. Specifically, demographics are shifting because of growth among historically underrepresented racial and ethnic minorities, including African Americans, Latinos, and Native Americans. At the same time, a declining number of skilled workers in science, technology, engineering, and mathematics (STEM) fields threatens U.S. global competitiveness and national security. Low participation, representation, engagement, and inclusion continue to reduce the intellectual capacity of the U.S. STEM workforce. The aforementioned societal changes require diversity in STEM education and the nation at large. Past research offers additional support for the importance of diversity. For example, racial diversity can improve educational outcomes such as complex thinking among students in college (Antonio et al., 2004). In STEM fields such as engineering, encouraging contact among undergraduate students from different economic, social, or racial and ethnic backgrounds can produce greater perceived learning gains (Strayhorn, Long, Williams, Dorimé-Williams, & Tillman-Kelly, 2014). Despite the societal and educational benefits of diversity, U.S. engineering and related STEM fields are dominated by persons whose background is White, male, English speaking, and middle class (National Academy of Engineering and National Research Council, 2009). Underrepresented populations’ limited access to engineering and related STEM fields has a historical context, a history predating landmark court decisions such as Brown vs. Board of Education that sought to provide equal educational opportunities to all racial/ethnic groups. The educational crisis for underrepresented minorities must be solved not only through encouragement and engagement of students but also through policy and practice in institutions. We believe that a new conversation about diversity needs to begin, a conversation examining policies and actions that pose unnecessary institutional barriers for underrepresented minority students in STEM fields such as engineering

Relationship between Biomechanical Characteristics of Spinal Manipulation and Neural Responses in an Animal Model: Effect of Linear Control of Thrust Displacement versus Force, Thrust Amplitude, Thrust Duration, and Thrust Rate

High velocity low amplitude spinal manipulation (HVLA-SM) is used frequently to treat musculoskeletal complaints. Little is known about the intervention’s biomechanical characteristics that determine its clinical benefit. Using an animal preparation, we determined how neural activity from lumbar muscle spindles during a lumbar HVLA-SM is affected by the type of thrust control and by the thrust's amplitude, duration, and rate. A mechanical device was used to apply a linear increase in thrust displacement or force and to control thrust duration. Under displacement control, neural responses during the HVLA-SM increased in a fashion graded with thrust amplitude. Under force control neural responses were similar regardless of the thrust amplitude. Decreasing thrust durations at all thrust amplitudes except the smallest thrust displacement had an overall significant effect on increasing muscle spindle activity during the HVLA-SMs. Under force control, spindle responses specifically and significantly increased between thrust durations of 75 and 150 ms suggesting the presence of a threshold value. Thrust velocities greater than 20–30 mm/s and thrust rates greater than 300 N/s tended to maximize the spindle responses. This study provides a basis for considering biomechanical characteristics of an HVLA-SM that should be measured and reported in clinical efficacy studies to help define effective clinical dosages

Birth Weights, Weaning Weights, and Average Daily Gain of Romosinuano-Sired Calves from First and Second Calving Angus X Brahman (F-1) Cows

Last updated: 6/12/200

Predicted Performance of an X-Ray Navigation System for Future Deep Space and Lunar Missions

In November 2017, the NASA Goddard Space Flight Center (GSFC) Station Explorer for X-ray Timing and Navigation Technology (SEXTANT) experiment successfully demonstrated the feasibility of X-ray Pulsar Navigation (XNAV) as part of the Neutron Star Interior Composition Explorer (NICER) mission, which is an X-ray Astrophysics Mission of Opportunity currently operating onboard the International Space Station (ISS). XNAV provides a GPS-like absolute autonomous navigation and timing capability available anywhere in the Solar System and beyond. While the most significant benefits of XNAV are expected to come in support of very deep-space missions, the absolute autonomous navigation and timing capability also has utility for inner Solar System missions where increased autonomy or backup navigation and timing services are required, e.g., address loss of communication scenarios.The NASA commitment to develop a Gateway to support exploration of the Moon and eventually Mars, as well as current and future robotic missions such as James Webb Space Telescope (JWST), New Horizons, and much more, certainly will tax the existing ground based infrastructure in terms of availability. There- fore, an extended look at the feasibility and potential performance of XNAV for comparable missions is warranted. In this paper, we briefly review the XNAV concept and present case studies of its utility and performance for a Gateway orbit, Sun-Earth libration orbit, and a deep space transit trajectory

DNA Methylation as a Biomarker for Cardiovascular Disease Risk

Elevated serum homocysteine is associated with an increased risk of cardiovascular disease (CVD). This may reflect a reduced systemic remethylation capacity, which would be expected to cause decreased genomic DNA methylation in peripheral blood leukocytes (PBL).We examined the association between prevalence of CVD (myocardial infarction, stroke) and its predisposing conditions (hypertension, diabetes) and PBL global genomic DNA methylation as represented by ALU and Satellite 2 (AS) repetitive element DNA methylation in 286 participants of the Singapore Chinese Health Study, a population-based prospective investigation of 63,257 men and women aged 45-74 years recruited during 1993-1998. Men exhibited significantly higher global DNA methylation [geometric mean (95% confidence interval (CI)): 159 (143, 178)] than women [133 (121, 147)] (P = 0.01). Global DNA methylation was significantly elevated in men with a history of CVD or its predisposing conditions at baseline (P = 0.03) but not in women (P = 0.53). Fifty-two subjects (22 men, 30 women) who were negative for these CVD/predisposing conditions at baseline acquired one or more of these conditions by the time of their follow-up I interviews, which took place on average about 5.8 years post-enrollment. Global DNA methylation levels of the 22 incident cases in men were intermediate (AS, 177) relative to the 56 male subjects who remained free of CVD/predisposing conditions at follow-up (lowest AS, 132) and the 51 male subjects with a diagnosis of CVD or predisposing conditions reported at baseline (highest AS 184) (P for trend = 0.0008) No such association was observed in women (P = 0.91). Baseline body mass index was positively associated with AS in both men and women (P = 0.007).Our findings indicate that elevated, not decreased, PBL DNA methylation is positively associated with prevalence of CVD/predisposing conditions and obesity in Singapore Chinese

The Proneural Molecular Signature Is Enriched in Oligodendrogliomas and Predicts Improved Survival among Diffuse Gliomas

The Cancer Genome Atlas Project (TCGA) has produced an extensive collection of ‘-omic’ data on glioblastoma (GBM), resulting in several key insights on expression signatures. Despite the richness of TCGA GBM data, the absence of lower grade gliomas in this data set prevents analysis genes related to progression and the uncovering of predictive signatures. A complementary dataset exists in the form of the NCI Repository for Molecular Brain Neoplasia Data (Rembrandt), which contains molecular and clinical data for diffuse gliomas across the full spectrum of histologic class and grade. Here we present an investigation of the significance of the TCGA consortium's expression classification when applied to Rembrandt gliomas. We demonstrate that the proneural signature predicts improved clinical outcome among 176 Rembrandt gliomas that includes all histologies and grades, including GBMs (log rank test p = 1.16e-6), but also among 75 grade II and grade III samples (p = 2.65e-4). This gene expression signature was enriched in tumors with oligodendroglioma histology and also predicted improved survival in this tumor type (n = 43, p = 1.25e-4). Thus, expression signatures identified in the TCGA analysis of GBMs also have intrinsic prognostic value for lower grade oligodendrogliomas, and likely represent important differences in tumor biology with implications for treatment and therapy. Integrated DNA and RNA analysis of low-grade and high-grade proneural gliomas identified increased expression and gene amplification of several genes including GLIS3, TGFB2, TNC, AURKA, and VEGFA in proneural GBMs, with corresponding loss of DLL3 and HEY2. Pathway analysis highlights the importance of the Notch and Hedgehog pathways in the proneural subtype. This demonstrates that the expression signatures identified in the TCGA analysis of GBMs also have intrinsic prognostic value for low-grade oligodendrogliomas, and likely represent important differences in tumor biology with implications for treatment and therapy

Disease and treatment patterns among patients with pouch-related conditions in a cohort of large tertiary care inflammatory bowel disease centers in the United States

BACKGROUND: Gaps exist in our understanding of the clinical course of pouch-related disorders. METHODS: We evaluated baseline disease activity and longitudinal treatment patterns among patients with inflammatory conditions of the pouch. RESULTS: Among 468 patients with an ileal pouch-anal anastomosis (IPAA), 94 (20%) had acute pouchitis, 96 (21%) had chronic pouchitis, and 192 (41%) had Crohn disease of the pouch. Following an IPAA, 38% of patients were treated with a biologic and 11% underwent inflammatory bowel disease- or bowel-related surgery. CONCLUSIONS: Treatment patterns after IPAA indicate that pouch-related disorders have a significant impact on individual patients and the healthcare system