Core power limits for a lead-bismuth natural circulation actinide burner reactor

The Idaho National Engineering and Environmental Laboratory and Massachusetts Institute of Technology are investigating the suitability of lead-bismuth cooled fast reactors for producing low-cost electricity as well as for actinide burning. The design being considered here is a pool type reactor that burns actinides and utilizes natural circulation of the primary coolant, a conventional steam power conversion cycle, and a passive decay heat removal system. Thermal-hydraulic evaluations of the actinide burner reactor were performed to determine allowable core power ratings that maintain cladding temperatures below corrosion-established temperature limits during normal operation and following a loss-of-feedwater transient. An economic evaluation was performed to optimize various design parameters by minimizing capital cost. The transient power limit was initially much more restrictive than the steady-state limit. However, enhancements to the reactor vessel auxiliary cooling system for transient decay heat removal resulted in an increased power limit of 1040 MWt, which was close to the steady-state limit. An economic evaluation was performed to estimate the capital cost of the reactor and its sensitivity to the transient power limit. For the 1040 MWt power level, the capital cost estimate was 49 mills per kWhe based on 1999 dollars.     

Spontaneous and induced minisatellite instability

Minisatellites provide not only the basis for DNA fingerprinting and DNA profiling but also extremely informative systems for analysing processes of tandem repeat turnover in the human genome. Minisatellite instability appears to involve distinct mutation processes in somatic and germline cells; in the germline, mutation is frequently dominated by inter-allelic conversion-like events most likely occurring at meiosis and apparently regulated by cis-acting mutation initiator elements. Attempts to define these initiators in transgenic mice have so far been thwarted by what appears to be a major human/mouse barrier to the inter-species transfer of repeat instability. Minisatellites not only show high frequency spontaneous mutation in the germline, but also appear to be very sensitive to mutation induction by ionizing radiation, both in experimentally irradiated mice and in human populations exposed following the Chernobyl disaster; the mechanisms of mutation induction by radiation remain enigmatic.     

Sex differences in effects of predictable and unpredictable footshock on fentanyl self-administration in rats.

An operant conditioning paradigm was used to examine effects of predictable and unpredictable footshock on oral fentanyl (50 μg/ml) self-administration (SA) in 12 female and 12 male Wistar rats (Rattus norvegicus). Rats were tested for drug SA under a progressive ratio schedule with and without repeated predictable or unpredictable footshock over 8 weeks. Female rats consumed greater amounts of fentanyl than did male rats. Male rats exhibited greater withdrawal behaviors following naloxone challenge. Predictable footshock with repeated exposure (i.e., chronic stress) was accompanied by greater fentanyl SA than was unpredictable footshock, particularly for female rats. Corticosterone levels were positively correlated with fentanyl SA. Predictability of the stressor also had a greater effect on maintenance of fentanyl SA than it did on relapse to fentanyl SA. Results suggest that sex plays an important role in drug-taking behavior by rats. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reactivity to positive and negative behavior in distressed and nondistressed married couples.

Tested the reactivity hypothesis that distressed married couples react more to recent, high-valence events (positive or negative) than their nondistressed counterparts. 21 happily married couples and 20 couples seeking marital therapy collected nightly data in the home for 2 wks, recording both the frequency of positive, negative, and neutral events and global daily satisfaction ratings. Ss also completed the Dyadic Adjustment Scale. As in past studies, and consistent with a behavioral model of marital distress, distressed couples reported lower rates of positive behavior and higher rates of negative behavior than did nondistressed. Consistent with the hypothesis, distressed spouses were more reactive to recent events than were nondistressed. Their subjective satisfaction with the relationship depended to a greater degree on the frequency of recent positive or negative events than was the case for happily married couples. Evidence is provided that these reactivity differences were not simply a function of differences in behavioral frequencies and that the process reactivity is separable—both experimentally and statistically—from the frequency of positive and negative exchanges. The relationship between reactivity and other variables of interest is examined. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Personal Characteristics of Salespeople and the Attractiveness of Alternative Rewards

How do personal characteristics of salespeople affect their desire for the various rewards available to them? Do younger salespeople desire different types and levels of rewards than older salespeople? Are there differences due to job tenure, marital status, family size, and so forth? In this article, the authors attempt to answer these questions. Based on an extensive investigation of the industrial sales forces from two large companies, the authors examine the relationship between personal characteristics and the sales force's valence for various rewards. Although some of the findings are consistent with current sales management practices, some are not, suggesting that present day thinking with respect to the design and administration of rewards may need more careful scrutiny.     

Comparing sets of circular orientations by modified chi-squared testing

This paper presents a program for initial pairwise inspection of multiple large sets of orientations, such as paleocurrent measurements, to see which sets are particularly similar, which are particularly different, and which need further examination. To do this, the paper proposes a modified chi-squared test that involves multiple recalculations based on reiterative regrouping of the dataset. This method not only evades problems caused by defining classes from an arbitrary starting point, but also avoids classes with too small an expected membership. It is NOT perfect or ideal, but it provides another way to start to investigate a large amount of paleocurrent data. It is conservative in calling attention to differences, particularly when concerned with small or extremely tightly grouped datasets.     

THE INFLUENCE OF SYNTHESIS PARAMETERS ON THE PRODUCTION OF MULTIWALLED CARBON NANOTUBES BY THE FERROCENE CATALYZED PYROLYSIS OF TOLUENE

A high yield (∼32 wt.%) of multiwalled carbon nanotubes was obtained in an iron catalyzed reaction. This was achieved in the temperature range 800-1000°C under an atmosphere of H₂/Ar by an improved solution injection method in a horizontal reactor using toluene as carbon source and ferrocene as catalyst precursor. The pyrolysis temperature, ferrocene concentration, solution feeding rate and carrier gas flow rate all influenced the yield of carbon nanotubes and the thickness of the aligned carbon nanotube films. The carbon nanotubes was prepared in high purity using optimized pyrolysis conditions.     

Maize populations with resistance to field contamination by aflatoxin B1

Maize (Zea mays L) germplasm is needed with resistance to infection by Aspergillus flavus and/or subsequent contamination by aflatoxin B₁ (AFB₁). A select group of maize populations were evaluated for their resistance to AFB₁ contamination at three locations. Four populations (Ibadan B and three others derived from crosses between Corn Belt inbreds and diploid perennial teosinte. Zea diploperennis) were compared with a susceptible hybrid check in a randomised complete block experiment with 10 replicates in Georgia, Missouri and South Carolina for two years. Ears were not inoculated, and naturally occurring concentrations of AFB₁ in harvested grain were analysed for population differences. Ibadan B and Mo2 W × Z diploperennis had significantly lower average amounts of AFB₁, 19 μg kg^?1 and 18 μg kg^?1, respectively, than other test entries. Backcrossing to susceptible Corn Belt inbreds produced populations as susceptible as the check when resistance was measured as the concentrations of AFB₁ in the grain. The consistency and significance of low AFB₁ concentrations for Ibadan B and Mo20W × Z diploperennis suggest that these may be useful sources of resistance.     

African infant precocity.

Reviews studies of African infant development with reference to the possible phenomenon of African infant precocity. Although the majority of studies report precocity, it is held that defects of measurement and design must preclude the conclusion that precocity is an established fact. The conclusion of precocity has always been based on comparison with test norms, whereas studies involving actual comparative samples do not find precocity. It is also argued that infant diffferences by social milieu afford the most sensible basis for the necessary introduction of independent variables in this research area, and that improved techniques of assessment should be applied both in the neonatal period and beyond. (74 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)