13,650 research outputs found
The effect of 1 to 5 keV electrons on the reproductive integrity of microorganisms
Microorganisms were exposed to simulated space environment in order to assess the effect of electrons in the energy range 1 to 5 keV on their colony-forming ability. The test system consisted of an electron gun and power supply, a dosimetry subsystem, and a vacuum subsystem. The system was capable of current densities ranging from 0.1 nA/sq cm to 5 micro A/sq cm on a 25 sq on target and an ultimate vacuum of 0.0006 N/sq m (0.000004 torr). The results of the experimental program show a significant reduction in microbial reproductive integrity
Surface roughness detector Patent
Roughness detector for recording surface pattern of irregularitie
The Loudest Event Statistic: General Formulation, Properties and Applications
The use of the loudest observed event to generate statistical statements
about rate and strength has become standard in searches for gravitational waves
from compact binaries and pulsars. The Bayesian formulation of the method is
generalized in this paper to allow for uncertainties both in the background
estimate and in the properties of the population being constrained. The method
is also extended to allow rate interval construction. Finally, it is shown how
to combine the results from multiple experiments and a comparison is drawn
between the upper limit obtained in a single search and the upper limit
obtained by combining the results of two experiments each of half the original
duration. To illustrate this, we look at an example case, motivated by the
search for gravitational waves from binary inspiral.Comment: 11 pages, 8 figure
DSK1, a novel kinesin-related protein from the diatom Cylindrotheca fusiformis that is involved in anaphase spindle elongation.
We have identified an 80-kD protein that is involved in mitotic spindle elongation in the diatom Cylindrotheca fusiformis. DSK1 (Diatom Spindle Kinesin 1) was isolated using a peptide antibody raised against a conserved region in the motor domain of the kinesin superfamily. By sequence homology, DSK1 belongs to the central motor family of kinesin-related proteins. Immunoblots using an antibody raised against a non-conserved region of DSK1 show that DSK1 is greatly enriched in mitotic spindle preparations. Anti-DSK1 stains in diatom central spindle with a bias toward the midzone, and staining is retained in the spindle midzone during spindle elongation in vitro. Furthermore, preincubation with anti-DSK1 blocks function in an in vitro spindle elongation assay. This inhibition of spindle elongation can be rescued by preincubating concurrently with the fusion protein against which anti-DSK1 was raised. We conclude that DSK1 is involved in spindle elongation and is likely to be responsible for pushing hal-spindles apart in the spindle midzone
Reduced chemistry for butanol isomers at engine-relevant conditions
Butanol has received significant research attention as a second-generation
biofuel in the past few years. In the present study, skeletal mechanisms for
four butanol isomers were generated from two widely accepted, well-validated
detailed chemical kinetic models for the butanol isomers. The detailed models
were reduced using a two-stage approach consisting of the directed relation
graph with error propagation and sensitivity analysis. During the reduction
process, issues were encountered with pressure-dependent reactions formulated
using the logarithmic pressure interpolation approach; these issues are
discussed and recommendations made to avoid ambiguity in its future
implementation in mechanism development. The performance of the skeletal
mechanisms generated here was compared with that of detailed mechanisms in
simulations of autoignition delay times, laminar flame speeds, and perfectly
stirred reactor temperature response curves and extinction residence times,
over a wide range of pressures, temperatures, and equivalence ratios. The
detailed and skeletal mechanisms agreed well, demonstrating the adequacy of the
resulting reduced chemistry for all the butanol isomers in predicting global
combustion phenomena. In addition, the skeletal mechanisms closely predicted
the time-histories of fuel mass fractions in homogeneous compression-ignition
engine simulations. The performance of each butanol isomer was additionally
compared with that of a gasoline surrogate with an antiknock index of 87 in a
homogeneous compression-ignition engine simulation. The gasoline surrogate was
consumed faster than any of the butanol isomers, with tert-butanol exhibiting
the slowest fuel consumption rate. While n-butanol and isobutanol displayed the
most similar consumption profiles relative to the gasoline surrogate, the two
literature chemical kinetic models predicted different orderings.Comment: 39 pages, 16 figures. Supporting information available via
https://doi.org/10.1021/acs.energyfuels.6b0185
Influence of training history and contraction velocity on hamstring muscle coactivation during maximal effort knee extension
When a muscle produces voluntary force, muscles on the opposite side of the joint, the antagonists, are also activated. While coactivation of the knee flexors during knee extension is presumed to increase joint stability by decreasing anterior shear force of the tibia on the femur, the coactivation of the hamstrings also produces what is called the antagonist torque. Systematic exercise in the form of resistance training can reduce antagonist muscle coactivation in healthy young adults. However, the mechanical consequence of this neurological adaptation is unclear. We thus hypothesized that previously strength-trained individuals would exhibit less antagonist coactivation, resulting in a reduced antagonist torque, and that with an increase in contraction speed there would be an increase in antagonist coactivation to slow the movement but there would be less of an increase due to speed in the trained compared with untrained individuals. Therefore, the purpose of this study was to determine the effects of training status on coactivation, i.e., antagonist torque, and on the speed-sensitivity of coactivation. Subjects for this study were fitted with surface EMG electrodes on their thigh muscles, and performed maximal effort knee extensions on a dynamometer, using shortening (concentric) and lengthening (eccentric) contractions at 30, 90, and 150°/s. As expected, trained individuals produced ~44% less coactivation at all contractions speeds. Against the hypothesis, coactivation did not increase in either group as velocity increased, as there was less than 10% difference in coactivation levels between the 3 speeds. Also against the hypothesis, as determined with an EMG-driven mathematical model, antagonist torque did not decrease with decreasing coactivation; in fact we see a trend towards the opposite for trained individuals. A borderline greater antagonist torque was noted in the trained compared to the untrained subjects even with decreased coactivation of the trained. These data suggest that antagonist muscle coactivation is less in trained healthy young adults but this reduced neural activation does not manifest itself in lower levels of antagonist torque. Therefore, leg strength training may increase muscle strength in part by reducing antagonist muscle coactivation without compromising joint stability.  M.S
A Longitudinal Study on the Drivers of Forestation
This paper studies the effects of population growth, income levels, and governance on forestation using longitudinal data covering 161 countries from 1996-2015. The study begins with a review of the empirical literature on deforestation and preservation of environmental quality. Then, we conduct our own empirical analysis through log differencing and analysis of annual percentage changes in forest area. We find evidence that these factors matter, but that the relationships are weak. The estimated effects do differ between our groupings of countries with regard to income levels as well as forest area sizes. Population growth generally leads to a reduction in forest area. Conversely, rising incomes slow deforestation and increase the chances of reforestation and afforestation. We witness the disappearance of a Kuznets curve relationship across all groups after individual country effects are included. A bettering of perceived rule of law, political stability, and reduction in corruption is also correlated with more positive forestation rates
Recent changes to the Federal Reserve's survey of terms of business lending
The Federal Reserve's quarterly Survey of Terms of Business Lending, which has been conducted for more than twenty years, collects information on interest rates and other characteristics of commercial bank business loans. The survey has been changed from time to time to recognize innovations in bank lending practices and to improve the measurement of the desired information. The most recent changes took effect with the May 1997 survey. The major improvement was the addition of an item measuring loan risk. In addition, the reporting panel, which had been limited to domestically chartered commercial banks was expanded to include a sample of U.S. branches and agencies of foreign banks, which now account for a significant proportion of business lending to U.S. firms. This article discusses the most recent changes made to the survey and presents some information now available from the new items being reported. It also summarizes information about the use of loan risk ratings from consultations conducted with a sample of the survey respondents during the process of planning the revisions to the survey.Commercial loans
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