Hydrodynamic Fuel Containment in an Open‐Cycle Gas Core Nuclear Rocket

A thermal‐hydraulic model of an open‐cycle gas core nuclear rocket is used to examine the fuel containment characteristics of the system. A parametric analysis is performed which studies how the average containment time, average number density, and mass loading of the fuel vary as a function of several design and operational parameters. The containing effect of the injected fluids is studied by varying the velocity and injection angle of the outer wall flow. The effect of rocket acceleration on the containment of the fuel is also examined. The results offer both a qualitative and quantitative look at fuel containment, thereby providing another step toward establishing the feasibility, or lack thereof, of the open‐cycle gas core nuclear rocket.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87619/2/1415_1.pd

Heat transfer model for an open‐cycle gas core nuclear rocket

A heat transfer model is developed to assess the propulsion capability of the open‐cycle gas core nuclear rocket. The model is used to determine the maximum specific impulse achievable without violating the wall material temperature and heat flux limits. For a 3000 MW reactor with a wall heat flux limit of 100 MW/m2, it is shown that a specific impulse of 3160 s and a thrust of 125 kN can be obtained.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87494/2/1083_1.pd

A Comprehensive Thermal‐Hydraulic Model of an Open‐Cycle Gas Core Nuclear Rocket

A thermal‐hydraulic model of an open‐cycle gas core nuclear rocket is developed. The two‐dimensional Navier‐Stokes equations, the energy equation, and the species diffusion equation are solved for high temperature two‐species gas flow. A description of the model and the method of solution is presented, as well as the results for a cylindrical gas core reactor design. The results provide valuable insight into the fluid flow and species mixing within an open‐cycle gas core nuclear rocket.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87616/2/473_1.pd

NQSI: Quality Schools Come From Quality People

Since the time of the now fabled one room schoolhouse, American schools have undergone tremendous change socially, structurally, and instructionally. Our public schools are under the microscope like never before. Charter schools and tuition vouchers circle above public education like vultures. New special education regulations loom menacingly on the horizon. Prophets of doom are on every street comer and in every Internet chat room. The Virginia General Assembly has mandated higher standards and tougher discipline. Innumerable publications document both technology\u27s explosion and the American family\u27s implosion. Against this seemingly foreboding backdrop, a school district in Southeastern Virginia researched, designed, and implemented the Norfolk Quality Schools Initiative (NQSI). Ever since the days of the old one room school house with its slate chalkboards and pot-bellied stove there have been scores and scores of movements to improve American education. Some have stressed the product while others have emphasized the process. The NQSI is not just another attempt at educational reform; it is a focused, inclusive and comprehensive plan for school revitalization and renewal. NQSI is unique in the fact that it employs a very specific process designed to develop a very specific product. Simply put, it is a systematic, outcome-based process

Thrust enhancement of the gasdynamic mirror (GDM) fusion propulsion system

The gasdynamic mirror propulsion system is a device that utilizes a magnetic mirror configuration to confine a hot plasma to allow fusion reactions to take place while ejecting a fraction of the energetic charged particles through one end to generate thrust. Because the fusion fuel is generally an isotope of hydrogen, e.g., deuterium or tritium, this propulsion device is capable of producing very large specific impulses (e.g., 200,000 seconds) but at modest thrusts. Since large thrusts are desirable, not only for reducing travel time but also for lifting sizable payloads, we have examined methods by which GDM’s thrust could be enhanced. The first consists of utilizing the radiation generated by the plasma, namely bremsstrahlung and synchrotron radiation, to heat a hydrogen propellant which upon exhausting through a nozzle produces the additional thrust. We asses the performance in this case by using an ideal model that ignores heat transfer considerations of the chamber wall, and one that takes into account heat flow and wall temperature limitations. We find in the case of a DT burning plasma that although thrust enhancement is significant, it was more than offset by the large drop in the specific impulse and a concomitant increase in travel time. The second method consisted of not altering the original GDM operation, but simply increasing the density of the injected plasma to achieve higher thrust. It is shown that the latter approach is more effective since it is compatible with improved performance in that it reduces trip time but at the expense of larger vehicle mass. For a D-He3D-He3 burning device the use of hydrogen to enhance thrust appears to be more desirable since the radiated power that goes into heating the hydrogen propellant is quite large. © 1997 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87386/2/1481_1.pd

THE EFFECT OF COMPRESSION TIGHTS AND DURATION OF TESTING ON CONTINUOUS JUMPING MECHANICAL POWER

INTRODUCTION: In order to improve their performance, athletes seek advancements in technology, such as clothing. Manufacturers of compression tights, advertise that their product adds support to lower extremity musculature, thus may slow the onset of fatigue. Few scientific studies, however, have been conducted to identify how advancements in apparel influence an athlete’s performance (Kraemer et al., 1996). The purpose of the present study was to identify the effects of compression tights on mechanical power for continuous jumping. Secondly, the effect of duration on the mechanical power output by using Bosco’s method (1983) over 15, 30, 45, and 60 sec time-frames, as well as the interaction between apparel and duration

Effects of a localized beam on the dynamics of excitable cavity solitons

We study the dynamical behavior of dissipative solitons in an optical cavity filled with a Kerr medium when a localized beam is applied on top of the homogeneous pumping. In particular, we report on the excitability regime that cavity solitons exhibits which is emergent property since the system is not locally excitable. The resulting scenario differs in an important way from the case of a purely homogeneous pump and now two different excitable regimes, both Class I, are shown. The whole scenario is presented and discussed, showing that it is organized by three codimension-2 points. Moreover, the localized beam can be used to control important features, such as the excitable threshold, improving the possibilities for the experimental observation of this phenomenon.Comment: 9 Pages, 12 figure

the role of cetuximab in converting initially unresectable colorectal cancer liver metastases for resection

Abstract In patients with metastatic colorectal cancer (mCRC) predominantly confined to the liver, whether a patient undergoes potentially curative resection of the liver lesions is a well-established principal determinant of long-term survival. There are a number of different agents, both chemotherapeutic and targeted biologic agents, which can aid in shrinking liver tumors, which would have otherwise been unresectable, allowing for potentially curative resection. The aim of this review article is to summarize the available evidence regarding optimal therapeutic strategies for converting initially unresectable metastases for potentially curative resection; we do not discuss patients who present with initially resectable disease. We have taken the approach to review trials that included R0 resection rates as one of the principal study endpoints and specifically enrolled patients with liver-limited disease. Primary tumor location has recently emerged as a putative prognostic and predictive factor in patients with mCRC; however, presently, there is a lack of resectability outcomes differentiating tumor location–defined subgroups, and several ongoing trials and retrospective analyses are anticipated to guide insights in the future. In conclusion, in patients with RAS wild-type mCRC, the data support preferential use of the anti-epidermal growth factor receptor monoclonal antibody cetuximab when combined with standard-of-care infusional doublet chemotherapy regimens (FOLFOX or FOLFIRI) for the conversion of initially unresectable metastases for potentially curative resection. Furthermore, we discuss data involving intensified chemotherapy regimens (i.e., 3-drug backbones such as FOLFOXIRI with or without a targeted biologic agent) to promote the conversion of initially unresectable metastases for potentially curative resection

Investigation of anatomical anomalies in Hanford Site mule deer

Rocky Mountain mule deer (Odocoileus hemionus hemionus), common residents of the Hanford Site, are an important part of the shrub-steppe ecosystem as well as being valued for aesthetics and hunting. Because mule deer have been protected from hunting on the Site for 50 years, the herd has developed unique population characteristics, including a large number of old animals and males with either large or atypically developed antlers, in contrast to other herds in the semi-arid regions of the Northwest. Hanford Site mule deer have been studied since 1991 because of the herd`s unique nature and high degree of public interest. A special study of the mule deer herd was initiated in 1993 after observations were made of a relatively large number of male deer with atypical, velvet-covered antlers. This report specifically describes our analyses of adult male deer found on the Site with atypical antlers. The report includes estimates of population densities and composition; home ranges, habitat uses, and dietary habits; natural and human-induced causes of mortality; and the herd`s overall health and reproductive status

Evaluation of Using Caged Clams to Monitor Contaminated Groundwater Exposure in the Near-Shore Environment of the Hanford Site 300 Area

The Asiatic clam (Corbicula fluminea) has been identified as an indicator species for locating and monitoring contaminated groundwater in the Columbia River. Pacific Northwest National Laboratory conducted a field study to explore the use of caged Asiatic clams to monitor contaminated groundwater upwelling in the 300 Area near-shore environment and assess seasonal differences in uranium uptake in relation to seasonal flow regimes of the Columbia River. Additional objectives included examining the potential effects of uranium accumulation on growth, survival, and tissue condition of the clams. This report documents the field conditions and procedures, laboratory procedures, and statistical analyses used in collecting samples and processing the data. Detailed results are presented and illustrated, followed by a discussion comparing uranium concentrations in Asiatic clams collected at the 300 Area and describing the relationship between river discharge, groundwater indicators, and uranium in clams. Growth and survival, histology, and other sources of environmental variation also are discussed