9,633 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
Lost Directions: U.S. Foreign Assistance Policy Since New Directions
International Development,
Antimicrobial therapy for otitis media with effusion ( secretory otitis media)
Objective. —To determine the effectiveness of antimicrobial treatment for otitis media with effusion ( secretory otitis media) in children.
Data Source. —We report the reexamination of a previously published study by Mandel et al that evaluated the efficacy of a 2-week course of antimicrobials (amoxicillin trihydrate) with and without a 4-week course of an oral decongestant-antihistamine combination in a double-blind, placebo-controlled, randomized trial involving 518 infants and children with otitis media with effusion.
Data Synthesis. —At 4 weeks, amoxicillin efficacy as determined by a tympanometric criterion (P=.121) or by a measure of improvement in hearing (P=.311) was insignificant. Only by otoscopic judgment, which is shown to contain a systematic bias as used in this clinical trial, could an argument be made for a marginal efficacy of amoxicillin at the 4-week end point. Logistic regression analyses of the combined effects of treatment and prognostic factors showed no significant differences between placebo- and antibiotic-treated groups for unilateral effusions and for bilateral effusions. When subjects with unilateral and bilateral effusions were combined, the estimated efficacy of antibiotic treatment was 12.3% by otoscopy (P =.014) and 4.8% by tympanometry (P =.171). We also demonstrate the sensitivity of outcome to diagnostic measures used and provide statistical evidence questioning the validity of otoscopic observations in this study. Six weeks after the termination of amoxicillin therapy, the recurrence of effusion was two to six times higher in the amoxicillin-treated children than in those treated with placebo (P=.001), and resolution of effusion was not significantly different among antibiotic and placebo groups (13.6% and 11.3%, respectively; P=.477).
Conclusions. —Amoxicillin with and without decongestant-antihistamine combination is not effective for the treatment of persistent asymptomatic middle-ear effusions in infants and children
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
Investigating Cut-point Methods in ROC Analysis: A Critique of Alternative Approaches
In 2017, Ilker Unal presented the Index of Union method for obtaining optimal cut-points in ROC analysis and claimed that it outperformed other methods, including the historied Youden Index. This is an investigation into that claim using generated data. It specifically pits the Youden Index method against the Index of Union (IU) method under various circumstances. The data sets have different ratios of diseased and non-diseased data points along with different ratios of true and false results based on a theoretical true cutpoint. The data was analyzed to see if any patterns emerged as to when the Youden Index obtain a cut-point closer to the theoretical true cut-point and when the IU method does. Although the IU method performed better in the majority of data sets, the Youden Index method did outperform the IU method at times. The IU method had a clear advantage in the case that the specificity and sensitivity were equal, while the Youden Index had an advantage when the area under the ROC curve was between 0.27 and 0.47. The results imply that there is good reason for the uncertainty in the landscape of methods for obtaining optimal cut-points, but there may be a good argument as to when to use one over another. More research should be done into the relationship between the area under the curve and these methods. In the meantime, medical researchers should not rely on a single method but rather take into the range of cut-points obtained by various methods
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)
Adolescent Expressive Reluctance Exacerbates Risk for Substance Use Following Daily Hassles
Previous research has established a link between adolescent’s perceived daily hassles and subsequent adjustment, but less is known about factors that exacerbate this relationship. The purpose of the present study was to identify if adolescent’s reluctance to express emotions moderated the association between their perceived daily hassles and subsequent substance use (i.e., alcohol, marijuana, tobacco). Cross-sectional data were obtained from a larger study that examined the effects of exposure to community violence among low-income, urban adolescents (N = 260, Mage = 14.14, SD = 1.62 years; 92% African American; 54% female). Linear regression analyses controlling for adolescent age, biological sex, and previous levels of drug use and daily hassles revealed that expressive reluctance moderated the association between perceived daily hassles and adolescent substance use. Specifically, for adolescents who were least likely to express their emotions, increases in perceived daily hassles were associated with significant increases in substance use. Further examination of domain-specific hassles revealed that expressive reluctance moderated the effects of academic, parental, and general neighborhood hassles on drug use, while no significant effects were detected for hassles related to friends or neighborhood danger. The present findings clarify which perceived daily hassles adversely affect adolescents, and how emotional expression can play an integral role in determining risk for poor coping behaviors.https://scholarscompass.vcu.edu/uresposters/1280/thumbnail.jp
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
Political Factors and Health Outcomes: Insight from Argentina's Provinces
This paper explores whether political factors were associated with health outcomes across Argentina's 23 provinces and Federal Capital from 1983 to 2005, controlling for national trends, per capita economic output, and other provincial specificities. The introduction of a gender quota for the lower house of the provincial legislature is found to have a statistically significant and substantively strong association with lower infant mortality. Most other political factors are found to be unassociated with the health share of provincial spending, attendance at birth by trained personnel, or infant survival. This lack of association stands in contrast to the findings of the cross-national literature, in which political factors are often found to be associated with health care spending, health service utilization, and health status. Differences in level of analysis (national vs. subnational) and in statistical technique help to explain these contrasting findings. Still, the analysis suggests that relations between political factors and health outcomes may be weaker than is sometimes suggested. As Amartya Sen has noted, democratic freedoms (and other political factors) create opportunities to improve other dimensions of human development. Whether these opportunities are seized depends on the actions of citizens and governments.human development, democracy, mortality, health care, gender, subnational, Argentina.
Evaluation of small area crop estimation techniques using LANDSAT- and ground-derived data
Studies completed in fiscal year 1981 in support of the clustering/classification and preprocessing activities of the Domestic Crops and Land Cover project. The theme throughout the study was the improvement of subanalysis district (usually county level) crop hectarage estimates, as reflected in the following three objectives: (1) to evaluate the current U.S. Department of Agriculture Statistical Reporting Service regression approach to crop area estimation as applied to the problem of obtaining subanalysis district estimates; (2) to develop and test alternative approaches to subanalysis district estimation; and (3) to develop and test preprocessing techniques for use in improving subanalysis district estimates
- …