Showing papers by "University of Oklahoma published in 1998"

The NextGen Model Atmosphere grid for $3000\le \Teff \le 10000\K$

Abstract: We present our NextGen Model Atmosphere grid for low mass stars for effective temperatures larger than $3000\K$. These LTE models are calculated with the same basic model assumptions and input physics as the VLMS part of the NextGen grid so that the complete grid can be used, e.g., for consistent stellar evolution calculations and for internally consistent analysis of cool star spectra. This grid is also the starting point for a large grid of detailed NLTE model atmospheres for dwarfs and giants (Hauschildt et al, in preparation). The models were calculated from $3000\K$ to $10000\K$ (in steps of $200\K$) for $3.5 \le \logg \le 5.5$ (in steps of 0.5) and metallicities of $-4.0 \le \mh \le 0.0$. We discuss the results of the model calculations and compare our results to the Kurucz 1994 grid. Some comparisons to standard stars like Vega and the Sun are presented and compared with detailed NLTE calculations.

Modulation of Diversity by Grazing and Mowing in Native Tallgrass Prairie

Abstract: Species diversity has declined in ecosystems worldwide as a result of habitat fragmentation, eutrophication, and land-use change. If such decline is to be halted ecological mechanisms that restore or maintain biodiversity are needed. Two long-term field experiments were performed in native grassland to assess the effects of fire, nitrogen addition, and grazing or mowing on plant species diversity. In one experiment, richness declined on burned and fertilized treatments, whereas mowing maintained diversity under these conditions. In the second experiment, loss of species diversity due to frequent burning was reversed by bison, a keystone herbivore in North American grasslands. Thus, mowing or the reestablishment of grazing in anthropogenically stressed grasslands enhanced biodiversity.

Bilateral orchiectomy with or without flutamide for metastatic prostate cancer

Abstract: Background Combined androgen blockade for the treatment of metastatic prostate cancer consists of an antiandrogen drug plus castration. In a previous trial, we found that adding the antiandrogen flutamide to leuprolide acetate (a synthetic gonadotropin-releasing hormone that results in medical ablation of testicular function) significantly improved survival as compared with that achieved with placebo plus leuprolide acetate. In the current trial, we compared flutamide plus bilateral orchiectomy with placebo plus orchiectomy. Methods We randomly assigned patients who had never received antiandrogen therapy and who had distant metastases from adenocarcinoma of the prostate to treatment with bilateral orchiectomy and either flutamide or placebo. Patients were stratified according to the extent of disease and according to performance status. Results Of the 1387 patients who were enrolled in the trial, 700 were randomly assigned to the flutamide group and 687 to the placebo group. Overall, the incidence of tox...

Multiple-drug resistant enterococci: the nature of the problem and an agenda for the future.

Abstract: Enterococci, leading causes of nosocomial bacteremia, surgical wound infection, and urinary tract infection, are becoming resistant to many and sometimes all standard therapies. New rapid surveillance methods are highlighting the importance of examining enterococcal isolates at the species level. Most enterococcal infections are caused by Enterococcus faecalis, which are more likely to express traits related to overt virulence but--for the moment--also more likely to retain sensitivity to at least one effective antibiotic. The remaining infections are mostly caused by E. faecium, a species virtually devoid of known overt pathogenic traits but more likely to be resistant to even antibiotics of last resort. Effective control of multiple-drug resistant enterococci will require 1) better understanding of the interaction between enterococci, the hospital environment, and humans, 2) prudent antibiotic use, 3) better contact isolation in hospitals and other patient care environments, and 4) improved surveillance. Equally important is renewed vigor in the search for additional drugs, accompanied by the evolution of new therapeutic paradigms less vulnerable to the cycle of drug introduction and drug resistance.

Low-dose aspirin to prevent preeclampsia in women at high risk

Abstract: Background Whether low-dose aspirin prevents preeclampsia is unclear. It is not recommended as prophylaxis in women at low risk for preeclampsia but may reduce the incidence of the disease in women at high risk. Methods We conducted a double-blind, randomized, placebo-controlled trial in four groups of pregnant women at high risk for preeclampsia, including 471 women with pregestational insulin-treated diabetes mellitus, 774 women with chronic hypertension, 688 women with multifetal gestations, and 606 women who had had preeclampsia during a previous pregnancy. The women were enrolled between gestational weeks 13 and 26 and received either 60 mg of aspirin or placebo daily. Results Outcome data were obtained on all but 36 of the 2539 women who entered the study. The incidence of preeclampsia was similar in the 1254 women in the aspirin group and the 1249 women in the placebo group (aspirin, 18 percent; placebo, 20 percent; P = 0.23). The incidences in the aspirin and placebo groups for each of the four hi...

Genome scan of human systemic lupus erythematosus: Evidence for linkage on chromosome 1q in African-American pedigrees

Abstract: Systemic lupus erythematosus (SLE) is an autoimmune disorder characterized by production of autoantibodies against intracellular antigens including DNA, ribosomal P, Ro (SS-A), La (SS-B), and the spliceosome. Etiology is suspected to involve genetic and environmental factors. Evidence of genetic involvement includes: associations with HLA-DR3, HLA-DR2, Fcγ receptors (FcγR) IIA and IIIA, and hereditary complement component deficiencies, as well as familial aggregation, monozygotic twin concordance >20%, λs > 10, purported linkage at 1q41–42, and inbred mouse strains that consistently develop lupus. We have completed a genome scan in 94 extended multiplex pedigrees by using model-based linkage analysis. Potential [log10 of the odds for linkage (lod) > 2.0] SLE loci have been identified at chromosomes 1q41, 1q23, and 11q14–23 in African-Americans; 14q11, 4p15, 11q25, 2q32, 19q13, 6q26–27, and 12p12–11 in European-Americans; and 1q23, 13q32, 20q13, and 1q31 in all pedigrees combined. An effect for the FcγRIIA candidate polymorphism) at 1q23 (lod = 3.37 in African-Americans) is syntenic with linkage in a murine model of lupus. Sib-pair and multipoint nonparametric analyses also support linkage (P 2.0). Our results are consistent with the presumed complexity of genetic susceptibility to SLE and illustrate racial origin is likely to influence the specific nature of these genetic effects.

The preterm prediction study: the value of new vs standard risk factors in predicting early and all spontaneous preterm births. NICHD MFMU Network.

Abstract: OBJECTIVES: This study was undertaken to determine the relationship between fetal fibronectin, short cervix, bacterial vaginosis, other traditional risk factors, and spontaneous preterm birth. METHODS: From 1992 through 1994, 2929 women were screened at the gestational age 22 to 24 weeks. RESULTS: The odds ratios for spontaneous preterm birth were highest for fetal fibronectin, followed by a short cervix and history of preterm birth. These factors, as well as bacterial vaginosis, were more strongly associated with early than with late spontaneous preterm birth. Bacterial vaginosis was more common--and a stronger predictor of spontaneous preterm birth--in Black women, while body mass index less than 19.8 was a stronger predictor in non-Black women. This analysis suggests a pathway leading from Black race through bacterial vaginosis and fetal fibronectin to spontaneous preterm birth. Prior preterm birth is associated with spontaneous preterm birth through a short cervix. CONCLUSIONS: Fetal fibronectin and a...

Risk Factors for Preeclampsia, Abruptio Placentae, and Adverse Neonatal Outcomes among Women with Chronic Hypertension

Abstract: Background Women with chronic hypertension who become pregnant have an increased risk of preeclampsia and adverse neonatal outcomes. However, within this group, the risk factors for these adverse events are not known. Methods We analyzed data on outcomes for 763 women with chronic hypertension enrolled in a multicenter trial of low-dose aspirin for the prevention of preeclampsia. Preeclampsia was defined as new-onset proteinuria (urinary protein excretion, ≥300 mg per 24 hours) in the 682 women without proteinuria at base line. It was defined according to strict clinical criteria in the 81 women who had proteinuria at base line. The end points were maternal and neonatal outcomes. Results Among the 763 women, 193 (25 percent) had preeclampsia. The frequency of preeclampsia was not affected by the presence of proteinuria at base line (27 percent among women with proteinuria, vs. 25 percent among those without it), but it was greater in women who had had hypertension for at least four years (31 percent vs. 2...

Measurements of the meson-photon transition form factors of light pseudoscalar mesons at large momentum transfer

Abstract: Using the CLEO II detector, we have measured the differential cross sections for exclusive two-photon production of light pseudoscalar mesons {pi}{sup 0}, {eta}, and {eta}{prime}. From our measurements we have obtained the form factors associated with the electromagnetic transitions {gamma}*{gamma} {yields} meson. We have measured these form factors in the momentum transfer ranges from 1.5 to 9, 20, and 30 GeV2 for {pi}{sup 0}, {eta}, and {eta}{prime}, respectively, and have made comparisons to various theoretical predictions.

Genetic and physical mapping of the Lps locus: identification of the toll-4 receptor as a candidate gene in the critical region.

Abstract: On the basis of 2093 meioses analyzed in two separate intraspecific backcrosses, the location of the mouse Lpsd mutation was circumscribed to a genetic interval 0.9 cM in size. A total of 19 genetic markers that lie in close proximity to the mutation were examined in mapping. Most of these were previously unpublished polymorphic microsatellites, identified by fragmentation of YAC and BAC clones spanning the region of interest. Lpsd was found to be inseparable from the microsatellite marker D4MIT178, and from three novel polymorphic microsatellites identified near D4MIT178. The mutation was confined between two novel microsatellite markers, herein designated "B" and "83.3." B lies centromeric to the mutation, and was separated by four crossovers in a panel of 1600 mice; 83.3 lies distal to the mutation and was separated by three crossovers in a panel of 493 mice. 66 BAC clones and one YAC clone were assembled to cover > 95% of the critical region. Estimates based on pulsed field gel electrophoresis and fluorescence in situ hybridization indicate that the The B-->83.3 interval is about 3.2 Mb in length. A minimal area of zero recombinational distance from Lpsd was also assigned, and found to occupy approximately 1.2 Mb of physical size. To identify gene candidates, nearly 40,000 sequencing runs were performed across the critical region. Selective hybridization and exon trapping were also employed to identify genes throughout the "zero" region. Only a single intact gene was identified within the entire critical region. This gene encodes the Toll-4 receptor, a member of the IL-1 receptor family.

Framework for AVO gradient and intercept interpretation

Abstract: Amplitude variation with offset (AVO) interpretation may be facilitated by crossplotting the AVO intercept (A) and gradient (B). Under a variety of reasonable petrophysical assumptions, brine‐saturated sandstones and shales follow a well‐defined “background” trend in the A-B plane. Generally, A and B are negatively correlated for “background” rocks, but they may be positively correlated at very high VP/VS ratios, such as may occur in very soft shallow sediments. Thus, even fully brine‐saturated shallow events with large reflection coefficients may exhibit large increases in AVO. Deviations from the background trend may be indicative of hydrocarbons or lithologies with anomalous elastic properties. However, in contrast to the common assumptions that gas‐sand amplitude increases with offset, or that the reflection coefficient becomes more negative with increasing offset, gas sands may exhibit a variety of AVO behaviors. A classification of gas sands based on location in the A-B plane, rather than on normal‐...

Ecto‐enzyme and signaling functions of lymphocyte CD 7 3

Abstract: CD73 or ecto-5'-nucleotidase (5'-NT) is a widely expressed ecto-enzyme which catalyzes the dephosphorylation of AMP and other nucleoside monophosphates. CD73 participates in purine salvage through this enzymatic activity, supplying cells with precursors for energy metabolism and nucleic acid biosynthesis. As an enzyme that produces adenosine, CD73 can also regulate adenosine receptor engagement in many tissues. However, CD73 also has functions independent of its enzyme activity. Like many glycosyl phosphatidylinositol (GPI)-anchored molecules, it transmits potent activation signals in T cells when ligated by antibodies. Less compelling evidence suggests that CD73 may function as a cell adhesion molecule. In the human immune system, CD73 is expressed on subsets of T and B cells, on germinal center follicular dendritic cells, and on thymic medullary reticular fibroblasts and epithelial cells. Many challenging areas remain to be explored before the role of CD73 in the immune system will be fully understood. These include an evaluation of the role of adenosine receptors in lymphoid development, the identification of physiological CD73 ligands, a functional assessment of the GPI anchor, and an analysis of the intricate cell-type-specific and developmental regulation of CD73 expression.

Adverse Effects of Diabetes on Multiple Cardiovascular Disease Risk Factors in Women: The Strong Heart Study

Abstract: OBJECTIVE Many studies have shown that diabetes increases the risk of cardiovascular disease (CVD) in women to a greater extent than in men. One explanation could be that diabetes has more adverse effects on CVD risk factors in women than in men. We compared diabetes-associated differences in CVD risk factors in men and women in the Strong Heart Study, a population-based study of CVD and its risk factors in American Indians. RESEARCH DESIGN AND METHODS A total of 1,846 men and 2,703 women between the ages of 45 and 74 years from 13 American Indian communities in three geographic areas underwent an examination that included a medical history; an electrocardiogram; anthropometric and blood pressure measurements; an oral glucose tolerance test; and measurements of fasting plasma lipoproteins, fibrinogen, insulin, HbA 1c , and urinary albumin. RESULTS Statistically significantly greater adverse differences in those with diabetes versus those without diabetes were observed in women than in men for waist-to-hip ratio, HDL cholesterol, apolipoprotein (apo)B, apoA1, fibrinogen, and LDL size. In multiple linear regression models adjusting for age, center, sex, and diabetes, the diabetes by sex interaction terms were statistically significant for waist-to-hip ratio, LDL cholesterol, HDL cholesterol, apoB, apoA1, fibrinogen, and LDL size. CONCLUSIONS Compared with diabetes-associated differences in men, diabetes in women was related to greater adverse differences in levels of several CVD risk factors. Although the magnitude of the individual diabetes-related differences between men and women was not large, the combined effects of these risk factor differences in diabetic women may be substantial. The apparent greater negative impact of diabetes on CVD risk factors in women may explain, in part, the greater risk for CVD in diabetic women.

The Clinical Validity of Normal Compression Ultrasonography in Outpatients Suspected of Having Deep Venous Thrombosis

Abstract: Background: Ultrasonography using vein compression accurately detects proximal deep venous thrombosis in symptomatic outpatients. Repeated testing is required for patients with normal results at pr...

Bond Rating Agencies and Stock Analysts: Who Knows What When?

Abstract: Both bond rating agencies and stock analysts evaluate publicly traded companies and com? municate their opinions to investors. Comparing the timeliness of each, we find that Granger causality flows both ways. While most bond downgrades are preceded by declines in actual and forecast earnings, both actual earnings and forecasts of future earnings tend to fall following downgrades. Although part of this post-downgrade forecast revision can be attributed to negative news regarding actual earnings, most appears to be reaction to the downgrade itself. We find little change in actual earnings following upgrades. Analysts, however, tend to increase their forecasts of future earnings.

The contemporary theory of metaphor

Abstract: This comparative study of Chinese and English metaphor contributes to the search for metaphoric universals by placing the contemporary theory of metaphor in a broad cross-linguistic and cross-cultural perspective. The author explores to what degree abstract reasoning is metaphorical and which conceptual metaphors are culture specific, wide spread or universal in a cognitive and cultural context. The empirical studies presented reinforce the view that metaphor is the main mechanism through which abstract concepts are comprehended and abstract reasoning is performed. They also support, from the perspective of Chinese, the candidacy of some conceptual metaphors for metaphorical universals. These include, for instance, the ANGER IS HEAT metaphor, the HAPPY IS UP metaphor (emotions), the TIME AS SPACE metaphor, and the Event Structure Metaphor. It seems that these conceptual metaphors are grounded in some basic human experiences that may be universal to all human beings.

Learning and change : implications for continuing medical education

Abstract: Medical education, particularly continuing medical education (CME), has been greatly influenced by studies of adult learning. The observation that it is not teaching but learning that leads doctors to change their practice has resulted in a shift in perspective: rather than education being regarded as instruction, it is regarded as facilitation of learning. This paradigm shift has been based on research into how and why doctors change their practice and into the role of learning in that process. The direction of continuing medical education in North America and elsewhere has changed in response to the new perspective that has emerged from contemporary studies of learning and change. The nature of this new perspective is evident from a comparison of the common elements of CME in the 1980s with the approach that is now being used. Traditionally a CME programme was an educational event that applied appropriate resources and methods to fulfill set instructional objectives. Such programmes were often considered to be good if the information was valuable, the lecturer skilful, and the setting comfortable. Too often, however, there was little or no actual effect on medical practice, even though all three conditions were met. The critical difference in the 1990s is that it has increasingly been accepted that CME programmes are based—or should be—on the principle of teaching and education as a means of facilitating learning. This new approach has been adopted in response to studies on how and why doctors change their performance in clinical practice and the role of learning in that process. This article describes some of these models and sets out the key principles that have emerged for continuing medical education in the past decade. #### Summary points The purpose of continuing medical education is to facilitate change in clinical practice CME should be based on the natural processes …

Numerical Solution of the Expanding Stellar Atmosphere Problem

Abstract: In this paper we discuss numerical methods and algorithms for the solution of NLTE stellar atmosphere problems involving expanding atmospheres, e.g., found in novae, supernovae and stellar winds. We show how a scheme of nested iterations can be used to reduce the high dimension of the problem to a number of problems with smaller dimensions. As examples of these sub-problems, we discuss the numerical solution of the radiative transfer equation for relativistically expanding media with spherical symmetry, the solution of the multi-level non-LTE statistical equilibrium problem for extremely large model atoms, and our temperature correction procedure. Although modern iteration schemes are very efficient, parallel algorithms are essential in making large scale calculations feasible, therefore we discuss some parallelization schemes that we have developed.

Situation awareness as a predictor of performance in en route air traffic controllers

Abstract: Air traffic control instructors controlled simulated traffic while a variety of techniques for determining situation awareness (SA) were implemented. SA was assessed using a self-report measure (th...

Habituation of Odor Responses in the Rat Anterior Piriform Cortex

Abstract: Simultaneous recordings of main olfactory bulb (MOB) and anterior piriform cortex (aPCX) neuron responses to repeated and prolonged odor pulses were examined in freely breathing, urethan-anesthetized rats. Comparisons of odor responses were made between multi-unit recordings of MOB activity and single-unit extracellular and intracellular recordings of Layer II/III aPCX neurons. Odor stimuli consisted of either 2-s pulses repeated at 30-s intervals or a single, prolonged 50-s stimulus. Respiration rate was monitored throughout. MOB and aPCX neuron responses to odor were quantified both through firing frequency and through the temporal patterning of firing over the respiratory cycle. The results demonstrate that aPCX neurons habituate significantly more (faster) than MOB neurons with both repeated and prolonged stimulation paradigms. This enhanced habituation is expressed as both a decrease in aPCX firing despite maintained odor-evoked MOB input and as a decrease in aPCX respiratory cycle entrainment despite maintained MOB cyclic input. Intracellular aPCX recordings suggest that several mechanisms may be involved in this experience-induced change in aPCX function, including 1) decreased excitatory driveof aPCX neurons, 2) decreased excitability of aPCX neurons,and/or 3) enhancement in odor-evoked inhibition of aPCX neurons. These studies provide the initial basis for understanding the mechanisms of nonassociative plasticity in olfactory cortex.

The National Severe Storms Laboratory Mesocyclone Detection Algorithm for the WSR-88D*

Abstract: The National Severe Storms Laboratory (NSSL) has developed a mesocyclone detection algorithm (NSSL MDA) for the Weather Surveillance Radar-1988 Doppler (WSR-88D) system designed to automatically detect and diagnose the Doppler radar radial velocity patterns associated with storm-scale (1–10-km diameter) vortices in thunderstorms. The NSSL MDA is an enhancement to the current WSR-88D Build 9.0 Mesocyclone Algorithm (88D B9MA). The recent abundance of WSR-88D observations indicates that a variety of storm-scale vortices are associated with severe weather and tornadoes, and not just those vortices meeting previously established criteria for mesocyclones observed during early Doppler radar studies in the 1970s and 1980s in the Great Plains region of the United States. The NSSL MDA’s automated vortex detection techniques differ from the 88D B9MA, such that instead of immediately thresholding one-dimensional shear segments for strengths comparable to predefined mesocyclone parameters, the initial stren...

Current and Future Research Methods in Strategic Management

Abstract: Early work in strategic management emphasized single case studies, followed by research on corporate diversification strategy, firm heterogeneity, strategic groups, and generic business strategies

The Occurrence of Tornadoes in Supercells Interacting with Boundaries during VORTEX-95

Abstract: During the Verifications of the Origins of Rotation in Tornadoes Experiment, nearly 70% of the significant tornadoes occurred near low-level boundaries not associated with the forward or rear flank downdrafts of supercells. In general, these were preexisting boundaries readily identified using conventional data sources. Most of the tornadoes occurred on the cool side of these low-level boundaries and generally within 30 km of the boundaries. It is likely that the low-level boundaries augmented the “ambient” horizontal vorticity, which, upon further generation in the forward-flank region, became sufficient to be associated with tornadic low-level mesocyclones. Some implications for forecasting and further research are discussed.

Type Ia supernovae and the Hubble constant

Abstract: ▪ Abstract The focus of this review is the work that has been done during the 1990s on using Type Ia supernovae (SNe Ia) to measure the Hubble constant (H0). SNe Ia are well suited for measuring H0. A straightforward maximum-light color criterion can weed out the minority of observed events that are either intrinsically subluminous or substantially extinguished by dust, leaving a majority subsample that has observational absolute-magnitude dispersions of less than σobs (MB) ≃ σobs (MV) ≃ 0.3 mag. Correlations between absolute magnitude and one or more distance-independent SN Ia or parent-galaxy observables can be used to further standardize the absolute magnitudes to better than 0.2 mag. The absolute magnitudes can be calibrated in two independent ways: empirically, using Cepheid-based distances to parent galaxies of SNe Ia, and physically, by light curve and spectrum fitting. At present the empirical and physical calibrations are in agreement at MB ≃ MV ≃ −19.4 or −19.5. Various ways that have been used ...

Risk factor clustering in the insulin resistance syndrome : The strong heart study

Abstract: The objective of this study was to examine how the major components of the insulin resistance syndrome relate to each other and to macrovascular disease in American Indians in the Strong Heart Study. The study cohort (4,228 resident tribal members 45-74 years old) underwent a personal interview and a physical examination between July 1989 and January 1992 at three centers: Arizona, Oklahoma, and North and South Dakota; blood samples were drawn and a 75-g oral glucose tolerance test was performed. Factor analysis was used to assess the clustering and interdependence of groups of insulin resistance syndrome variables. Within both diabetic and nondiabetic groups, three factors emerged. In nondiabetic participants, a cluster of glucose, body mass index, and insulin accounted for 35% (male) and 32% (female) of the total variance in all variables considered, and a cluster of systolic blood pressure and diastolic blood pressure accounted for 25% and 22% in men and women, respectively. Both clusters were positively associated with coronary heart disease but not peripheral vascular disease. In diabetic participants, the combination of systolic and diastolic blood pressures was the most important factor, but the cluster was not associated with coronary heart disease or peripheral vascular disease. A component containing high density lipoprotein cholesterol, triglycerides, and glucose had a positive association with coronary heart disease in diabetic women and with peripheral vascular disease in both sexes. The association of clusters of risk factors and their relations with coronary heart disease provide important clues that may be used in understanding the metabolic disorders associated with insulin resistance and diabetes.