Investigations of the potential performance characteristics of selected contact lubricants for applications in miniature slip-ring capsules of the type used in ST 124 M stabilized inertial guidance platforms Final technical report, 27 Mar. 1968 - 30 Apr. 1970

Performance characteristics of liquid and solid lubricants for contacts of miniature slip-ring capsule

Population Dynamics of \u3ci\u3eMicrotus Ochrogaster\u3c/i\u3e in Eastern Kansas

Four eastern Kansas populations of the prairie vole, Microtus ochrogaster were live trapped from 1970—73 to gain insight into the population regulation of this species. All four populations exhibited a 2—yr cycle in numbers with peak densities generally occurring in June 1972. Peak densities were followed by a decline in numbers, a recovery, and a population crash in spring 1973. Reproductive parameters changed dramatically as density rose and fell. The summer breeding season in the crash year of 1973 was shortened by at least 3 mo. A reduction in breeding activity occurred during the summer of every year of the study. The highest amount of reproduction occurred during the spring and fall. More voles were breeding during the winter before the peak year (1971—72) than during either the preceding or succeeding winter. There was no deviation from a sex ratio of 1 in the populations. Mortality rates had a strong impact on changes in numbers. Survival rates of juveniles and subadults in the population were significantly lower than adults in the summer breeding season. Adults survived better during winter than during summer. Survival of ♂ ♂ and ♀ was correlated and was relatively low during episodes of decreasing density. The survival of voles between weaning and trappable size was high during periods of increasing density and low during periods of declining density. A multiple regression analysis was performed to determine the relative usefulness of four demographic variables in predicting mean rate of population increase. The analysis indicated that early juvenile and ♀ survival are the best predictors of population growth. Growth of voles in the populations was assessed from body weight distributions and instantaneous growth rate per body weight. There was no shift in body weight toward heavier animals in peak populations and instantaneous growth rates were erratic. Finally, inconsistencies in these results compared with other microtine studies, such as the short peak phase, lack of a well—defined breeding season, a summer breeding depression, and the absence of a shift towards heavier animals in the peak phase, are discussed in relation to a single or multifactor hypothesis for explaining population cycles

The Reproductive Cycle of \u3ci\u3eMicrotus ochrogaster\u3c/i\u3e in Eastern Kansas

About 800 Microtus ochrogaster were live—trapped at biweekly intervals from May 1971 through March 1973 in 3 grassland study areas in eastern Kansas, USA. Details of reproduction were determined by autopsy. Population density increased through the first winter, reached a peak in April 1972, then declined sharply during that summer and beyond. Body length, but not body mass, tended to be positively related to density. Both sexes matured at about the same weight; development was somewhat prolonged during the winter months, especially in the winter preceding the population peak. Pregnancy rates were high, approaching maximal iteroparity, throughout the study, with intervals of nonbreeding in both Julys, and in August and December of the population decline. Embryo counts increased significantly during the months of peak density but did not diminish in the period of the population decline. There was no association between either maternal weight or parity and number of embryos. Corpora counts were not higher in heavy or multiparious ♀ ♀, nor did the level of prenatal mortality increase during the period of greatest density. Except for a few individuals taken in July and August 1971, ♂ ♂ with a mass 30 g or more were judged to be fertile, as were a majority of the 20 to 29—g ♂ ♂. Body weight and testes weight were significantly correlated in fertile ♂ ♂ but not in nonfertile ♂ ♂. These reproductive findings were applied to a model of population regulation of microtine cycles. The pattern of reproduction of Kansas and Indiana prairie voles was compared. Three concordant lines of evidence seem to indicate that Kansas and possibly other geographical populations of prairie voles have adjusted the breeding schedule to accommodate both hot and dry summers and cold, snowy winters. Pregnancy rate, litter size, and adjusted testes weight all show a significant increase in March–April and September–October and a decrease in midsummer and midwinter. Thus the pattern of reproduction of Kansas prairie voles may represent a composite of the patterns shown by the dry—adapted species, such as Microtus californicus, and the cold—adapted microtines, such as Microtus pennsylvanicus. Based on the observations of this study, Kansas prairie voles seem to have adjusted to both harsh seasons by breeding more or less continuously, with the midsummer depression possibly reflecting the Great Plains origin of the species, and the winter depression being a facultative response to weather, density, or quality of habitat

The contrasting oceanography of the Rhodes Gyre and the Central Black Sea

The Rhodes Gyre, a prominent feature of the oceanography of the eastern Mediterranean, is modelled as a vertical, continuous flow, cylindrical reactor illuminated during the day at its upper end. If the Gyre is supposed to be in a steady state whilst the concentrations, C, of a chemical are being measured, the nett rate of formation or consumption of the chemical is given by -w d C/d z + u d C/d r, where w is the upward velocity of the water in the vertical, z , direction and u is the velocity of the water in the radial, r, direction. The behaviour of w and u is analysed to show that the Gyre may be used as a field laboratory in which rates of chemical change may be derived from depth profiles together with values of the surface velocities of the Gyre waters. In contrast, the central Black Sea is modelled as an ideal, strongly stratified sea in which the nett rates of formation or consumption of chemicals under steady state conditions are given by Ds d2C/ds 2, where s is the water density and Ds is an eddy diffusion coefficient. Computations reveal that, given better knowledge of its eddy diffusion coefficients, the Black Sea can also be treated as a field laboratory where rates of reaction mediated by bacteria may be derived from depth profiles

Impaired contextual modulation of memories in PTSD: an fMRI and psychophysiological study of extinction retention and fear renewal

Post-traumatic stress disorder (PTSD) patients display pervasive fear memories, expressed indiscriminately. Proposed mechanisms include enhanced fear learning and impaired extinction or extinction recall. Documented extinction recall deficits and failure to use safety signals could result from general failure to use contextual information, a hippocampus-dependent process. This can be probed by adding a renewal phase to standard conditioning and extinction paradigms. Human subjects with PTSD and combat controls were conditioned (skin conductance response), extinguished, and tested for extinction retention and renewal in a scanner (fMRI). Fear conditioning (light paired with shock) occurred in one context, followed by extinction in another, to create danger and safety contexts. The next day, the extinguished conditioned stimulus (CS+E) was re-presented to assess extinction recall (safety context) and fear renewal (danger context). PTSD patients showed impaired extinction recall, with increased skin conductance and heightened amygdala activity to the extinguished CS+ in the safety context. However, they also showed impaired fear renewal; in the danger context, they had less skin conductance response to CS+E and lower activity in amygdala and ventral-medial prefrontal cortex compared with combat controls. Control subjects displayed appropriate contextual modulation of memory recall, with extinction (safety) memory prevailing in the safety context, and fear memory prevailing in the danger context. PTSD patients could not use safety context to sustain suppression of extinguished fear memory, but they also less effectively used danger context to enhance fear. They did not display globally enhanced fear expression, but rather showed a globally diminished capacity to use contextual information to modulate fear expression

Additional Comments on Reproductive Strategies and Population Fluctuations in Microtine Rodents

Recently, Schaffer and Tamarin (1973) proposed a model relating changes in reproductive effort (RE) to fluctuating densities in microtine rodents (lemmings and voles). They assumed (and presented data supporting this assumption) that the major effect of increased crowding would be a reduction in survival among prereproductives, thereby lowering the effective fecundity (Schaffer and Rosenzweig 1977) of their parents. As a consequence, Schaffer and Tamarin argued that the optimal reproductive expenditure, E(N), should decline with increasing population size, N. They also deduced the shape of the zero-growth isocline, N*(E), for differing levels of RE and plotted both E(N) and N*(E) on a graph whose axes are reproductive expenditure and population density (Fig1 a)

Computer recommendations for an automatic approach and landing system for V/STOL aircraft. Volume 1 - Computer recommendations

Evaluation of digital computer for V/STOL aircraft automatic approach and landing syste

Towards hardware acceleration of neuroevolution for multimedia processing applications on mobile devices

This paper addresses the problem of accelerating large artificial neural networks (ANN), whose topology and weights can evolve via the use of a genetic algorithm. The proposed digital hardware architecture is capable of processing any evolved network topology, whilst at the same time providing a good trade off between throughput, area and power consumption. The latter is vital for a longer battery life on mobile devices. The architecture uses multiple parallel arithmetic units in each processing element (PE). Memory partitioning and data caching are used to minimise the effects of PE pipeline stalling. A first order minimax polynomial approximation scheme, tuned via a genetic algorithm, is used for the activation function generator. Efficient arithmetic circuitry, which leverages modified Booth recoding, column compressors and carry save adders, is adopted throughout the design

Psychological Responses Prior to a Strenuous Task Involving an Injured Joint

Injuries are an inherent risk of sport participation. Roughly 68% of athletes experience an athletic injury during their college career, with over half being injuries to the lower extremity (Hootman, Dick & Agel, 2007). While much attention has been given to the physical effects of an injury, the psychological ramifications can also affect an athlete’s recovery from injury. According to Quinn & Fallon (2008), an athlete can physically recover from an injury however they may not attain a complete psychological recovery. An athlete’s performance can be affected negatively if they return to sport participation without recovering psychologically from their injury, which can also lead to a risk of re-injury or receiving additional injuries (Quinn & Fallon, 2008). Two variables related to psychological recovery include re-establishment of confidence and a decrease in fear of re-injury (Magyar & Duda, 2000; Walker & Heaney, 2013). Additionally, an athlete may feel reluctance to perform skills that require the site of injury to be used which affects subsequent performance. An athlete’s fear of re-injury can negatively affect athletes’ performance by undermining an athlete’s confidence in obtaining their pre-injury sport performance (Arden, Taylor, Feller & Webster, 2012). The purpose of this study was to determine how psychological responses to injury, namely sport resumption confidence, fear of re-injury, and injury perception change throughout the rehabilitation process. These variables were examined in relation to performing a strenuous isokinetic dynamometer task on an injured joint (e.g., knee, ankle). Participants (N=21; 62% female) completed psychometrically sound measures designed to assess confidence, fear and injury perception across three groups of athletes: healthy (n = 9), injured (n = 6), and rehabilitated (n = 6). All subjects were told they would be completing a maximal isokinetic contraction task on the lower extremity that had been injured before completing the survey. Only healthy and rehabilitated athletes actually performed the task at the completion of the survey. ANOVA was utilized to compare group differences on study variables. There was a significant difference between groups with regard to fear (healthy=1.62 ± 0.03; injured=4.09 ± 0.10; rehabilitated=3.17 ± 0.61; p \u3c .05) and confidence (healthy=5.82 ± 0.68; injured=2.99 ± 0.06; rehabilitated=4.06 ± 0.58; p \u3c .01) where healthy athletes reported the highest confidence and lowest fear across groups. Additionally, injured athletes reported the lowest confidence and highest fear across groups. There were no group differences found with regard to injury perception (healthy=0.00 ± 0.00; injured=1.01 ± 0.41; rehabilitated=0.07 ± 0.09). This study extends the current sport injury research base by identifying changes in key psychological variables across the healthy-injured-rehabilitated continuum of the collegiate sport experience

Measurement techniques and instruments suitable for life-prediction testing of photovoltaic arrays

Array failure modes, relevant materials property changes, and primary degradation mechanisms are discussed as a prerequisite to identifying suitable measurement techniques and instruments. Candidate techniques and instruments are identified on the basis of extensive reviews of published and unpublished information. These methods are organized in six measurement categories - chemical, electrical, optical, thermal, mechanical, and other physicals. Using specified evaluation criteria, the most promising techniques and instruments for use in life prediction tests of arrays were selected