7,993 research outputs found
Abundances of sodium, sulfur, and potassium in lunar volcanic glasses: Evidence for volatile loss during eruption
Six varieties of lunar volcanic glass are known to occur within the Apollo 17 sample collection. Investigations have shown that 25 volatile elements are known to be concentrated on the exterior surfaces of individual volcanic glass spheres. Since bulk analyses of volcanic glass provide an integrated abundance of an element on and with the glass spherules, other methods must be relied on to determine the interior abundance of an element. The interior abundance of an element with a volcanic glass sphere establishes the abundance of that element in the melt at the time of quench. The current study is part of a comprehensive attempt to measure the abundance of three volatile elements (Na, S, and K) within representative spheres of the 25 varieties of lunar volcanic glass currently known to exist at the Apollo landing sites. Comparison of the measured abundances of these elements within the interiors of individual glasses with bulk analyses and crystalline mare basalts will furnish new constraints on the geochemical behavior of volatile elements during lunar mare volcanism
Rating of 29 community problems as perceived by rural leaders in Tennessee counties, 1980 compared to 1984
The purpose of this study was to compare leaders in ruralTennessee counties ratings of 29 potential community problem areas in 1980 compared to 1984. Data were obtained in 1980 and 1984 from community leaders through mail survey conducted by Extension agents in rural Tennessee counties. The four most urban counties were not included in this study (i.e., Shelby, Davidson, Knox and Hamilton). The community resource development questionnaire was developed by Extension specialists in the Agriculture Economics and Resource Development section. County leaders from the following 12 organizations and agencies were surveyed: Rural Development Committee; county government officials; Home Demonstration Club presidents; community club presidents; senior 4-H club presidents; service club presidents; county agriculture Extension committee; ministers; merchants; bankers; school principals; and newspaper editors. Data were coded and processed for computer analysis. Computations were made by The University of Tennessee, Knoxville Computing Center. The chi square test was used to determine strengths and significance of relationship between independent and dependent variables. Chi square values which achieved .05 probability level were accepted as significant. Major findings included the following: 1. Leaders in each of the five Extension related audiences indicated that the condition of local agriculture was no better in 1984 than it was in 1980. Leaders in the 12 audience groups and in the business and professional audience groups indicated that the condition of agriculture in rural Tennessee counties was better in 1980 than it was in 1984. 2. The condition of local industry, jobs available, family income, and job training was rater higher in 1980 than in 1984 by leaders in the 12 audience groups, business and professional groups and leaders in the five Extension related audience groups. The condition of school buildings and of education in the rural counties was rated higher in 1984 than in 1980 by leaders in the 12 audience groups, business and professional groups and leaders in the five Extension related audience groups. Ratings of the conditions of seven public service and health facilities and services (i.e., public libraries, public health service, doctors and dentists, hospitals and clinics, nursing homes, public buildings, fire protection, sewage disposl, water supply, and garbage and trash disposal) by leaders in the 12 audience groups, business and professional groups and Extension related audience groups were higher in 1984 than in 1980. Ratings of the conditions of five of the 10 potential problem areas ragarding the general environment and recreation opportunities (i.e., general community appearance, community organizations, condition of homes, condition of parks and playgrounds, and road maintenance) by leaders in all 12 audience groups and Extension related audience groups were higher in 1984 than in 1980. Ratings of land use planning and family living conditions did not differ in 1980 compared to 1984. Conservation of natural resources was rated higher by leaders in all 12 audience groups and in business and professional groups in 1980 than in 1984. Likewise, public transportation was rated higher in 1980 than it was in 1984. Implications and recommendations also were included in the study
Assessment of the Fluorescence and Auger Data Base used in Plasma Modeling
We have investigated the accuracy of the 1s-vacancy fluorescence data base of
Kaastra & Mewe (1993, A&AS, 97, 443) resulting from the initial atomic physics
calculations and the subsequent scaling along isoelectronic sequences. In
particular, we have focused on the relatively simple Be-like and F-like
1s-vacancy sequences. We find that the earlier atomic physics calculations for
the oscillator strengths and autoionization rates of singly-charged B II and Ne
II are in sufficient agreement with our present calculations. However, the
substantial charge dependence of these quantities along each isoelectronic
sequence, the incorrect configuration averaging used for B II, and the neglect
of spin-orbit effects (which become important at high-Z) all cast doubt on the
reliability of the Kaastra & Mewe data for application to plasma modeling.Comment: 19 pages with 6 figures, AAS TeX, accepted for publication in Ap
Cytokine gene polymorphisms in preterm infants with necrotising enterocolitis: genetic association study
BACKGROUND The inflammatory cytokine cascade is implicated in the pathogenesis of necrotising enterocolitis (NEC). Genetic association studies of cytokine polymorphisms may help to detect molecular mechanisms that are causally related to the disease process. AIM To examine associations between the common genetic variants in candidate inflammatory cytokine genes and NEC in preterm infants. METHODS Multi-centre case-control and genetic association study. DNA samples were collected from 50 preterm infants with NEC and 50 controls matched for gestational age and ethnic group recruited to a multi-centre case-control study. Ten candidate single-nucleotide polymorphisms in cytokines previously associated with infectious or inflammatory diseases were genotyped. The findings were included in random-effects meta-analyses with data from previous genetic association studies. RESULTS All allele distributions were in Hardy-Weinberg equilibrium. None of the studied cytokine polymorphisms was significantly associated with NEC. Four previous genetic association studies of cytokine polymorphisms and NEC in preterm infants were found. Meta-analyses were possible for several single-nucleotide polymorphisms. These increased the precision of the estimates of effect size but did not reveal any significant associations. CONCLUSIONS The available data are not consistent with more than modest associations between these candidate cytokine variant alleles and NEC in preterm infants. Data from future association studies of these polymorphisms may be added to the meta-analyses to obtain more precise estimates of effects sizes.The study was funded by Tenovus (Scotland)
Time Ordering in Kicked Qubits
We examine time ordering effects in strongly, suddenly perturbed two-state
quantum systems (kicked qubits) by comparing results with time ordering to
results without time ordering. Simple analytic expressions are given for state
occupation amplitudes and probabilities for singly and multiply kicked qubits.
We investigate the limit of no time ordering, which can differ in different
representations.Comment: 26 pages, 5 figure
Tests on puddle weld connections
PREFACE This non-interpretive report contains the results of 90 tests on circular and oblong puddle weld connections. The connections involved test specimens constructed of flat steel plates and thin connecting sheets of varying thicknesses (10 to 28 gage) with the welds to be studied forning the bond between them. Testing consisted of tensile loading to ultimate failure. This work was carried out under contract with the Engineering Division of the American Iron and Steel Institute
Film calibration for the Skylab/ATM S-056 X-ray telescope
The sensitometry and film calibration effort for the Skylab/ATM S-056 X-ray telescope is summarized. The apparatus and procedures used are described together with the two types of flight film used, Kodak SO-212 and SO-242. The sensitometry and processing of the flight film are discussed, and the results are presented in the form of the characteristic curves and related data. The use of copy films is also discussed
Population control of 2s-2p transitions in hydrogen
We consider the time evolution of the occupation probabilities for the 2s-2p
transition in a hydrogen atom interacting with an external field, V(t). A
two-state model and a dipole approximation are used. In the case of degenerate
energy levels an analytical solution of the time-dependent Shroedinger equation
for the probability amplitudes exists. The form of the solution allows one to
choose the ratio of the field amplitude to its frequency that leads to temporal
trapping of electrons in specific states. The analytic solution is valid when
the separation of the energy levels is small compared to the energy of the
interacting radiation.Comment: 6 pages, 3 figure
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