3,558 research outputs found
Research in and application of state variable feedback design of guidance control systems for aerospace vehicles Progress report
Weighted least squares parameter estimation, Kalman filter, and random search problems for aerospace guidance control system desig
Fast inactivation in Shaker K+ channels. Properties of ionic and gating currents.
Fast inactivating Shaker H4 potassium channels and nonconducting pore mutant Shaker H4 W434F channels have been used to correlate the installation and recovery of the fast inactivation of ionic current with changes in the kinetics of gating current known as "charge immobilization" (Armstrong, C.M., and F. Bezanilla. 1977. J. Gen. Physiol. 70:567-590.). Shaker H4 W434F gating currents are very similar to those of the conducting clone recorded in potassium-free solutions. This mutant channel allows the recording of the total gating charge return, even when returning from potentials that would largely inactivate conducting channels. As the depolarizing potential increased, the OFF gating currents decay phase at -90 mV return potential changed from a single fast component to at least two components, the slower requiring approximately 200 ms for a full charge return. The charge immobilization onset and the ionic current decay have an identical time course. The recoveries of gating current (Shaker H4 W434F) and ionic current (Shaker H4) in 2 mM external potassium have at least two components. Both recoveries are similar at -120 and -90 mV. In contrast, at higher potentials (-70 and -50 mV), the gating charge recovers significantly more slowly than the ionic current. A model with a single inactivated state cannot account for all our data, which strongly support the existence of "parallel" inactivated states. In this model, a fraction of the charge can be recovered upon repolarization while the channel pore is occupied by the NH2-terminus region
Gestational Form of Supplemental Selenium (Se) Affects Steroidogenic Gene Expression in the Newborn Calf Testis
Selenium (Se) is an important trace mineral in the diet of cattle. Our objective was to determine whether the form of supplemental Se fed to the dam would affect the expression of genes regulating steroidogenesis in the newborn testis. Twenty-four Angus-cross cows were assigned randomly (n=8) to individual ad libitum access of a mineral mix containing 35 ppm of Se supplied as sodium selenite (inorganic, ISe; Prince Se), Sel-Plex (organic, OSe; Sel-Plex, Alltech) or a 50/50 mix of ISe/OSe (MIX) 4 months prior to breeding and throughout gestation. All male calves were castrated within 2 days of birth and total testis RNA was subjected to microarray analysis using the Affymetrix Bovine 1.0 ST array. Ingenuity Pathway Analysis of differentially expressed genes, separated by one-way ANOVA (p\u3c0.05) and a post-hoc LSD test, identified eight mRNAs associated with steroidogenesis. Specifically, mRNAs involved in the conversion of testosterone to estradiol were increased in the testis of OSe-supplemented when compared to ISe-supplemented animals, and mRNAs encoding genes regulating the conversion of androstenedione to testosterone or androstenedione to estradiol were decreased in the testis of MIX-supplemented when compared to ISe-supplemented cows.Expression in the neonate may equate to differences in fertility in the adult animal
Design and Testing of a Novel Adhesion and Locomotion Method for Wall Climbing Vehicles
The objective of this project was to design, construct and test a wall climbing vehicle which uses a novel vacuum tread system for both adhesion and locomotion. The design and manufacturing of this proof of concept vehicle is detailed with particular emphasis on the design decisions that proved most impactful to the performance of both the vehicle and the tread system. Adhesion performance was characterized by a series of tests that validate the concept, but also identify improvements and design recommendations for future embodiments of the adhesion/locomotion system
Reversals in nature and the nature of reversals
The asymmetric shape of reversals of the Earth's magnetic field indicates a
possible connection with relaxation oscillations as they were early discussed
by van der Pol. A simple mean-field dynamo model with a spherically symmetric
coefficient is analysed with view on this similarity, and a comparison
of the time series and the phase space trajectories with those of paleomagnetic
measurements is carried out. For highly supercritical dynamos a very good
agreement with the data is achieved. Deviations of numerical reversal sequences
from Poisson statistics are analysed and compared with paleomagnetic data. The
role of the inner core is discussed in a spectral theoretical context and
arguments and numerical evidence is compiled that the growth of the inner core
might be important for the long term changes of the reversal rate and the
occurrence of superchrons.Comment: 24 pages, 12 figure
Sex, Power, and Women: Female Viewers’ Perceptions of Popular Music Video Themes
Research has linked viewing highly sexual music videos with increased gender role acceptance, and concern over personal physical appearance. However, very few studies have assessed individual differences in how music video sexual content is perceived, and no studies to date have addressed non-objectifying sexual content. In the present study, fifteen college women were exposed to 21 pop music videos and asked to categorize each video on the basis of whether it depicted women a) as sex objects, b) using sex as a source of power, or c) non-sexually. At least one video achieved perfect consensus amongst the participants for each category of sexual content, indicating that not all highly sexual portrayals of women are seen as objectifying by college women. However, the participants did not categorize the remaining videos in a uniform manner, indicating that there are considerable individual differences in the perception of music video sexual content
Control system design using optimization techniques Final report
Optimization techniques for control of fuel valve systems for air breathing jet engines and 40-60 inlet control problem
An addendum to: a meta-analysis of hypothethical bias in stated preference valuation
<p>A recent study published by Murphy et al. (2005) reported results of a meta-analysis of hypothetical bias using 28 valuation studies. The authors found a median ratio of hypothetical to actual values of 1.35 but they did not investigate the ratio of variances of the hypothetical and actual value distributions, which is of great relevance in joint stated and revealed preference analysis. We propose an addendum to Murphy et al. (2005) to provide some insights on the distribution of the scale factor across 23 studies for which relevant data is available. We distinguish three types of dispersion parameters reported in the literature. We find that the ratio of real to hypothetical standard deviations of marginal distributions of WTP is about 0.6.</p
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