28,374 research outputs found
The preparation and evaluation of high-purity, fine-grained tungsten and tungsten alloy castings summary report
High purity, cylindrical castings of high melting point materials such as tungsten and tungsten alloy
Two systems developed for purifying inert atmospheres
Two systems, one for helium and one for argon, are used for purifying inert atmospheres. The helium system uses an activated charcoal bed at liquid nitrogen temperature to remove oxygen and nitrogen. The argon system uses heated titanium sponge to remove nitrogen and copper wool beds to remove oxygen. Both use molecular sieves to remove water vapor
Response of selected microorganisms to experimental planetary environments
The anaerobic utilization of phosphite or phosphine and the significance of this conversion to potential contamination of Jupiter were investigated. A sporeforming organism was isolated from Cape Canaveral soil which anaerobically converts hypophosphite to phosphate. This conversion coincides with an increase in turbidity of the culture and with phosphate accumulation in the medium. Investigations of omnitherms (organisms which grow over a broad temperature range, i.e. 3 -55 C were also conducted. The cellular morphology of 28 of these isolates was investigated, and all were demonstrated to be sporeformers. Biochemical characterizations are also presented. Procedures for replicate plating were evaluated, and those results are also presented. The procedures for different replicate-plating techniques are presented, and these are evaluated on the basis of reproducibility, percentage of viable transfer, and ease of use. Standardized procedures for the enumeration of microbial populations from ocean-dredge samples from Cape Canaveral are also presented
The Connection between Supernova Remnants and the Galactic Magnetic Field: A Global Radio Study of the Axisymmetric Sample
The study of supernova remnants (SNRs) is fundamental to understanding the
chemical enrichment and magnetism in galaxies, including our own Milky Way. In
an effort to understand the connection between the morphology of SNRs and the
Galactic magnetic field (GMF), we have examined the radio images of all known
SNRs in our Galaxy and compiled a large sample that have an "axisymmetric"
morphology, which we define to mean SNRs with a "bilateral" or "barrel"-shaped
morphology, in addition to one-sided shells. We selected the cleanest examples
and model each of these at their appropriate Galactic position using two GMF
models, those of Jansson & Farrar (2012a), which includes a vertical halo
component, and Sun et al. (2008) that is oriented entirely parallel to the
plane. Since the magnitude and relative orientation of the magnetic field
changes with distance from the sun, we analyse a range of distances, from 0.5
to 10 kpc in each case. Using a physically motivated model of a SNR expanding
into the ambient GMF, we find the models using Jansson & Farrar (2012a) are
able to reproduce observed morphologies of many SNRs in our sample. These
results strongly support the presence of an off-plane, vertical component to
the GMF, and the importance of the Galactic field on SNR morphology. Our
approach also provides a potential new method for determining distances to
SNRs, or conversely, distances to features in the large-scale GMF if SNR
distances are known.Comment: 24 pages, 8 figures plus one 5-page appendix figure, 3 tables,
accepted to A&
Can Self-Organizing Maps accurately predict photometric redshifts?
We present an unsupervised machine learning approach that can be employed for
estimating photometric redshifts. The proposed method is based on a vector
quantization approach called Self--Organizing Mapping (SOM). A variety of
photometrically derived input values were utilized from the Sloan Digital Sky
Survey's Main Galaxy Sample, Luminous Red Galaxy, and Quasar samples along with
the PHAT0 data set from the PHoto-z Accuracy Testing project. Regression
results obtained with this new approach were evaluated in terms of root mean
square error (RMSE) to estimate the accuracy of the photometric redshift
estimates. The results demonstrate competitive RMSE and outlier percentages
when compared with several other popular approaches such as Artificial Neural
Networks and Gaussian Process Regression. SOM RMSE--results (using
z=z--z) for the Main Galaxy Sample are 0.023, for the
Luminous Red Galaxy sample 0.027, Quasars are 0.418, and PHAT0 synthetic data
are 0.022. The results demonstrate that there are non--unique solutions for
estimating SOM RMSEs. Further research is needed in order to find more robust
estimation techniques using SOMs, but the results herein are a positive
indication of their capabilities when compared with other well-known methods.Comment: 5 pages, 3 figures, submitted to PAS
High-Performance Silicon-Based Multiple Wavelength Source
We demonstrate a stable CMOS-compatible on-chip multiple-wavelength source by
filtering and modulating individual lines from a frequency comb generated by a
microring resonator optical parametric oscillator.. We show comb operation in a
low-noise state that is stable and usable for many hours. Bit-error rate
measurements demonstrate negligible power penalty from six independent
frequencies when compared to a tunable diode laser baseline. Open eye diagrams
confirm the fidelity of the 10 Gb/s data transmitted at the comb frequencies
and the suitability of this device for use as a fully integrated silicon-based
WDM source.Comment: 3 pages, 3 figure
The impact of defamilisation measures on gender and pensions: A comparison between the UK and seven other European countries
This article uses individual-based and state-led care-focused defamilisation indices to explore women's employment opportunities and experiences and their implications for pension contributions. These two types of defamilisation indices are applied to eight European countries (Belgium, Finland, France, the Netherlands, Denmark, Norway, Sweden and the UK) which shows that the UK has less generous defamilisation measures than its European counterparts. It indicates that the use of defamilisation measures along with pension policies which are not based on the male breadwinner ideology have the capacity to moderate economic inequalities between men and women in older age
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