PEGASUS: A multi-megawatt nuclear electric propulsion system

A propulsion system (PEGASUS) consisting of an electric thruster driven by a multimegawatt nuclear power system is proposed for a manned Mars mission. Magnetoplasmadynamic and mercury-ion thrusters are considered, based on a mission profile containing a 510-day burn time (for a mission time of approximately 1000 days). Both thrusters are capable of meeting the mission parameters. Electric propulsion systems have significant advantages over chemical systems, because of high specific impulse, lower propellant requirements, and lower system mass. The power for the PEGASUS system is supplied by a boiling liquid-metal fast reactor. The power system consists of the reactor, reactor shielding, power conditioning subsystems, and heat rejection subsystems. It is capable of providing a maximum of 8.5 megawatts of electrical power of which 6 megawatts is needed for the thruster system, leaving 1.5 megawatts available for inflight mission applications

A guide to the Thalassinidea (Crustacea: Malacostraca: Decapoda) of the South Atlantic Bight

Ghost shrimp and mud shrimp in the decapod infraorder Thalassinidea are ecologically important members of many benthic intertidal and shallow subtidal infaunal communities, largely due to the sediment filtration and mixing that result from their burrowing and feeding behavior. These activities considerably modify their immediate environment and have made these cryptic animals extremely interesting to scientists in terms of their behavior, ecology, and classification. Over 20 years ago, seven species of thalassinideans were known from the South Atlantic Bight (Cape Hatteras, NC to Cape Canaveral, FL). During this study, the examination of extensive collections from the National Museum of Natural History (NMNH), the Southeastern Regional Taxonomic Center (SERTC), and regional institutions, resulted in the identification of 14 species of thalassinideans currently known to occur within this region. The family Axiidae is represented by three species: Axius armatus, Calaxius jenneri, and Paraxiopsis gracilimana; the Callianassidae by six: Biffarius biformis, B. cf. fragilis, Callichirus major, Cheramus marginatus, Gilvossius setimanus, and Necallianassa berylae; the Calocarididae by two: Calocaris templemani and Acanthaxius hirsutimanus; and the families Laomediidae, Thomassiniidae, and Upogebiidae are each represented by one: Naushonia crangonoides, Crosniera wennerae, and Upogebia affinis, respectively. An illustrated key is presented for species level identification and supplemental notes on the ecology, distribution, and taxonomy of the species are provided.(PDF file contains 38 pages.

Aerosol Data Sources and Their Roles within PARAGON

We briefly but systematically review major sources of aerosol data, emphasizing suites of measurements that seem most likely to contribute to assessments of global aerosol climate forcing. The strengths and limitations of existing satellite, surface, and aircraft remote sensing systems are described, along with those of direct sampling networks and ship-based stations. It is evident that an enormous number of aerosol-related observations have been made, on a wide range of spatial and temporal sampling scales, and that many of the key gaps in this collection of data could be filled by technologies that either exist or are expected to be available in the near future. Emphasis must be given to combining remote sensing and in situ active and passive observations and integrating them with aerosol chemical transport models, in order to create a more complete environmental picture, having sufficient detail to address current climate forcing questions. The Progressive Aerosol Retrieval and Assimilation Global Observing Network (PARAGON) initiative would provide an organizational framework to meet this goal

Open surgical partial nephrectomy for upper tract urothelial carcinoma

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106973/1/iju12301.pd

Automating Scoring of Delay Discounting for the 21- and 27-Item Monetary Choice Questionnaires

Delay discounting describes the process wherein rewards lose value as a function of their delayed receipt; how quickly rewards lose value is termed the rate of delay discounting. Rates of delay discounting are robust predictors of much behavior of societal importance. One efficient approach to obtaining a human subject’s rate of delay discounting is via the 21- and 27-item Monetary Choice Questionnaires, brief dichotomous choice tasks that assess preference between small immediate and larger delayed monetary outcomes. Unfortunately, the scoring procedures for the Monetary Choice Questionnaires are rather complex, which may serve as a barrier to their use. This report details a freely available Excel-based spreadsheet tool that automatically scores Monetary Choice Questionnaire response sets, using both traditional and contemporary/ advanced approaches. An overview of the Monetary Choice Questionnaire and its scoring algorithm is provided. We conclude with general considerations for using the spreadsheet tool

Delays in diagnosis and bladder cancer mortality

BACKGROUND: Mortality from invasive bladder cancer is common, even with high-quality care. Thus, the best opportunities to improve outcomes may precede the diagnosis. Although screening currently is not recommended, better medical care of patients who are at risk (ie, those with hematuria) has the potential to improve outcomes. METHODS: The authors used the Surveillance, Epidemiology, and End Results-Medicare linked database for the years 1992 through 2002 to identify 29,740 patients who had hematuria in the year before a bladder cancer diagnosis and grouped them according to the interval between their first claim for hematuria and their bladder cancer diagnosis. Cox proportional hazards models were fitted to assess relations between these intervals and bladder cancer mortality, adjusting first for patient demographics and then for disease severity. Adjusted logistic models were used to estimate the patient's probability of receiving a major intervention. RESULTS: Patients (n = 2084) who had a delay of 9 months were more likely to die from bladder cancer compared with patients who were diagnosed within 3 months (adjusted hazard ratio [HR], 1.34; 95% confidence interval [CI], 1.20-1.50). This risk was not markedly attenuated after adjusting for disease stage and tumor grade (adjusted HR, 1.29; 95% CI, 1.14-1.45). In fact, the effect was strongest among patients who had low-grade tumors (adjusted HR, 2.11; 95% CI, 1.69-2.64) and low-stage disease (ie, a tumor [T] classification of Ta or tumor in situ; adjusted HR, 2.02; 95% CI, 1.54-2.64). CONCLUSIONS: A delay in the diagnosis of bladder cancer increased the risk of death from disease independent of tumor grade and or disease stage. Understanding the mechanisms that underlie these delays may improve outcomes among patients with bladder cancer. Cancer 2010. © 2010 American Cancer Society.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78303/1/25310_ftp.pd