Showing papers by "University of Oklahoma published in 1993"
TL;DR: In this paper, the interaction process and performance of culturally homogeneous and culturally diverse groups were studied for 17 weeks, and the results showed that homogeneous groups scored higher on both process effectiveness and performance effectiveness.
Abstract: The interaction process and performance of culturally homogeneous and culturally diverse groups were studied for 17 weeks. Initially, homogeneous groups scored higher on both process and performance effectiveness. Over time, both types of group showed improvement on process and performance, and the between-group differences converged. By week 17, there were no differences in process or overall performance, but the heterogeneous groups scored higher on two task measures, Implications for management and future research are given.
1,447 citations
TL;DR: In this article, a new, practical and theoretically correct methodology is proposed for identi$cation and characterization of hydraulic units based on a modified Kozeny-Carmen equation and the concept of mean hydraulic raditis.
Abstract: Understanding complex variations in pare geomet~ within different Iithofacies is the key to improved reservoir description and exploitation. Core data provide in~ornration on various depositional and diagenetic controls on pore geometry. Variations in pore geometrical attributes in rum, de$ne the existenceof distinct zones(hydraulic units) with similar f?uid-jlow characteristics. Classic discrimination of mck types has been based on subjective geological observations and on empirical relationships between the log of permeability versus porosity. Howevec for any porosity within a given mck type,permeability can vary by several orders of nragnitnde, which indicates the existenceof severalflow units. In this papec a new, practical and theoretically correct methodology is proposedfor identi$cation and characterization of hydraulic units widtin mappable geological units (facies). The technique is based on a modified Kozeny-Carmen equation and the conceptof mean hydraulic raditis. The equation indicatesIhat for any hydraulic unit, a log-log p!ot of a “Reservoir Quality index,” (RQI), which is equal to 0.0314 ~. versus a “Normalized PorosityIndex” (+=) which is equal to WI-W should yield a straight line with a unit slope. 7he intercept of the unit slope line with +Z = 1, designated as the “FIow Zme Indicator” (M), is a unique parameter for each hydraulic unit. RQI, 4, and FZI are based on stressed potvsity and permeability data measuredon core samples.
878 citations
TL;DR: A family of statistical models termed random regression models were used that provide a more realistic approach to analysis of longitudinal psychiatric data and indicated that both person-specific effects and serial correlation play major roles in the longitudinal psychiatric response process.
Abstract: L studies have a prominent role in psychiatric research; however, statistical methods for analyzing these data are rarely commensurate with the effort involved in their acquisition. Frequently the majority of data are discarded and a simple end-point analysis is performed. In other cases, so called repeated-measures analysis of variance procedures are used with little regard to their restrictive and often unrealistic assumptions and the effect of missing data on the statistical properties of their estimates. We explored the unique features of longitudinal psychiatric data from both statistical and conceptual perspectives. We used a family of statistical models termed random regression models that provide a more realistic approach to analysis of longitudinal psychiatric data. Random regression models provide solutions to commonly observed problems of missing data, serial correlation, time-varying covariates, and irregular measurement occasions, and they accommodate systematic person-specific deviations from the average time trend. Properties of these models were compared with traditional approaches at a conceptual level. The approach was then illustrated in a new analysis of the National Institute of Mental Health Treatment of Depression Collaborative Research Program dataset, which investigated two forms of psychotherapy, pharmacotherapy with clinical management, and a placebo with clinical management control. Results indicated that both person-specific effects and serial correlation play major roles in the longitudinal psychiatric response process. Ignoring either of these effects produces misleading estimates of uncertainty that form the basis of statistical tests of hypotheses.
680 citations
TL;DR: In this article, the authors explored the generality of Gottfredson and Hirschi's theory by examining the link between low self-control and these imprudent behaviors.
Abstract: Gottfredson and Hirschi'sA General Theory of Crime contends that individual differences in involvement in criminal and analogous behavior are due largely to individual differences in the personality trait they call low self-control. Among the various behaviors considered analogous to crime are imprudent behaviors such as smoking, drinking, and gambling. This research explores the generality of Gottfredson and Hirschi's theory by examining the link between low self-control and these imprudent behaviors. The results are mixed. In support of the theory, the data reveal a modest but significant effect of a scale designed to capture the various components of low self-control on an index of imprudent behavior. A more detailed analysis, however, reveals that some of the components of low self-control, specifically those probably linked to low intelligence, detract from the scale's predictive power. In fact, one of the components, risk-seeking, is more predictive than the more inclusive scale. Furthermore, one of the imprudent acts, smoking, appears to be unaffected by low self-control. These contradictory findings suggest the need for theoretical refinements.
446 citations
TL;DR: Overall, the plasma triglyceride level showed no independent association with coronary mortality, but in subgroups of subjects with lower HDL and LDL cholesterol levels and in younger subjects, defined a priori, an association was observed, although this association was small and was not statistically significant after an adjustment for the plasma glucose level.
Abstract: Background Whether the plasma triglyceride level is a risk factor for coronary heart disease has been controversial, and evaluation of the triglyceride level as a risk factor is fraught with methodologic difficulties. Methods We studied the association between plasma triglyceride levels and the 12-year incidence of death from coronary heart disease in 10 North American populations participating in the Lipid Research Clinics Follow-up Study, while adjusting for the potential confounding effects of other risk factors for cardiovascular disease, including the level of high-density lipoprotein (HDL) cholesterol. All analyses were sex-specific, and separate analyses were performed in high and low strata of HDL cholesterol, low-density lipoprotein (LDL) cholesterol, fasting plasma glucose, and age. Results The rates of coronary death in both men and women increased with the triglyceride level. In Cox proportional-hazards models adjusted for age, in which the natural log of the triglyceride levels was used to gi...
405 citations
TL;DR: This controlled-release mesalamine preparation is safe and effective at 4 g/day as a single agent in treatment of active Crohn's disease of the ileum and colon.
335 citations
TL;DR: P-selectin and PAF are components of an adhesion and activation cascade, but have distinct roles: P- selectin tethers and captures the PMN, whereas PAF mediates juxtacrine activation.
Abstract: Polymorphonuclear leukocytes (PMNs) bind rapidly and reversibly to endothelial cells induced to express P-selectin, a glycoprotein that mediates adhesive intercellular interactions. In addition, PMNs adherent to endothelium expressing P-selectin demonstrate an intracellular Ca2+ transient, functionally up-regulate beta-2-integrins (CD11/CD18 glycoproteins), become polarized in shape, and are primed for enhanced degranulation when subsequently stimulated with chemotactic factors. However, P-selectin induces none of these responses directly when used alone, when incorporated into model membranes, or when expressed by transfected cells. The absence of direct activation of the PMNs is not due to competing antiinflammatory effects of P-selectin; instead, purified P-selectin and P-selectin in membranes support agonist-stimulated PMN responses. Furthermore, tethering of PMNs to endothelial surfaces by P-selectin is required for priming to occur efficiently, as shown by experiments with blocking monoclonal antibodies. The priming event is directly mediated by the signaling molecule, platelet-activating factor (PAF), and is inhibited by blocking the PAF receptor on PMNs. Thus, P-selectin and PAF are components of an adhesion and activation cascade, but have distinct roles: P-selectin tethers and captures the PMN, whereas PAF mediates juxtacrine activation. In vivo, selectins may facilitate interaction of target cells with membrane-bound molecules that send intercellular signals, in addition to mediating rolling of leukocytes and other adhesive functions.
335 citations
01 Apr 1993
TL;DR: A comprehensive and unified analysis of symmetry in a wide variety of Cayley graphs of permutation groups, including the star graph, bubble-sort graph, modified bubble- sort graph, complete-transposition graph, prefix-reversal graph, alternating-group graph, binary and base-b (b ≥ 3) hypercube, cube connected cycles, bisectional graph, folded hypercube and binary orthogonal graph is provided.
Abstract: This survey provides a comprehensive and unified analysis of symmetry in a wide variety of Cayley graphs of permutation groups. These include the star graph, bubble-sort graph, modified bubble-sort graph, complete-transposition graph, prefix-reversal graph, alternating-group graph, binary and base-b (b ≥ 3) hypercube, cube connected cycles, bisectional graph, folded hypercube and binary orthogonal graph. In addition, we also define a variety of generalizations of the hypercube and orthogonal graphs. The types of symmetry analyzed include vertex and edge transitivity, distance regularity and distance transitivity. Since these notions of symmetry depend on the shortest paths, as a by product we also describe the shortest path routing algorithms for these graphs. We present a number of open problems related to the networks described in this paper.
328 citations
TL;DR: In this paper, a nonconvex decision space is decomposition into a small number of subsets such that each of the associated dispatch problems is either infeasible or one that can be directly solved via the conventional Lagrangian relaxation approach.
Abstract: A method is described for solving the reserve constrained economic dispatch problem when some of the online generating units have prohibited operating zone(s). For a unit with prohibited zone(s), the zone(s) divide the operating region between the minimum generation limit (Pmin) and the maximum generation limit (Pmax) into disjoint convex subregions. These disjoint subregions form a nonconvex decisions space and the associated economic dispatch problem is thus a nonconvex optimization problem. As a result, the conventional Lagrangian relaxation (LR) approach (e.g. the lambda - delta iterative approach) cannot be applied directly. The method proposed decomposes the nonconvex decision space into a small number of subsets such that each of the associated dispatch problems is either infeasible or one that can be directly solved via the conventional LR approach. Based on the decomposition, the optimal solution is the least costly one among all the feasible solutions of the associated dispatch problems. Examples are also given to illustrate the proposed method. >
298 citations
TL;DR: The signal sequence is in an aqueous milieu at an early stage in the translocation of a nascent secretory protein across the endoplasmic reticulum membrane using fluorescent probes incorporated into the signal sequence of fully assembled ribosome-nascent chain-membrane complexes.
294 citations
TL;DR: Clostridium ljungdahlii is the first acetogen in clostridial 23S rRNA homology group I, and was isolated from chicken yard waste for its ability to produce ethanol from synthesis gas.
Abstract: Clostridium ljungdahlii sp. nov. strain ATCC 49587T (T = type strain) was isolated from chicken yard waste for its ability to produce ethanol from synthesis gas. This gram-positive, motile, sporeforming rod's metabolism was primarily acetogenic. C. ljungdahlii grew with carbon monoxide, hydrogen and carbon dioxide, ethanol, pyruvate, arabinose, xylose, fructose, or glucose. Methanol, ferulic acid, lactate, galactose, and mannose did not support growth. The G+C content was 22 to 23 mol%. C. ljungdahlii is the first acetogen in clostridial 23S rRNA homology group I.
TL;DR: In this article, the Smagorinsky subgrid model has been revised to account for grid anisotropy on the basis of energy equilibrium considerations in isotropic turbulence, and Deardorff's (1970) estimate involving an equivalent grid scale Delta(eq) = (Delta1 Delta2 Delta3) exp 1/3 is given a rigorous basis.
Abstract: The paper revises the Smagorinsky subgrid model to properly account for grid anisotropy on the basis of energy equilibrium considerations in isotropic turbulence. For moderate resolution anisotropies, Deardorff's (1970) estimate involving an equivalent grid scale Delta(eq) = (Delta1 Delta2 Delta3) exp 1/3 is given a rigorous basis. It is argued that the results obtained should be used in conjunction with the dynamic model of Germano et al. (1991) whenever the anisotropy of the test filter differs significantly from that of the basic grid.
TL;DR: Caution is recommended in the use of arthroscopic procedures for the competitive athlete in whom a second surgery and rehabilitation might mean loss of more sports partici pation, and for the younger patient, who may not have com plied with the immobilization protocol.
Abstract: The purpose of this paper was to report our experience with an arthroscopic technique of repair for the Bankart lesion following shoulder instability. Twenty-seven pa tients (average age, 21.7 years) were followed for an average of 36 months after arthroscopic suture stabili zation of anterior shoulder instability. Patients were excluded if instability was multidirectional or voluntary and if there was radiographic evidence of a significant loss of glenoid bone stock. Clinical evaluation using a functional grading system showed that 10 patients were rated as excellent, 5 good, and 12 poor. Fourteen patients returned to their previous level of activity. There were 12 patients rated as failed; all had recurrent instability of the shoulder. Success was associated with a period of immobilization of 3 weeks or longer and a history of acute injury, especially subluxation. Failures were associated with shorter immobilization periods after surgery and in patients who had recurrent dislo cations. The younger patie...
TL;DR: In this paper, new ReOs isotopic results for Os-poor basalts from St. Helena, the Comores, Samoa, Pitcairn and Kerguelen dramatically expand the known range of initial 186Os/187Os ratios in OIBs to values as high as 1.7.
TL;DR: The mechanism by which A. lanipes influences algae and benthic insects is evaluated by comparing patterns of algal biomass, taxonomic composition, and insect abundance between shrimp-exclusion and shrimp-presence treatments both with and without manual sediment removal, supporting the hypothesis that sediment removal enhances the biovolume of understory algal taxa.
Abstract: Freshwater shrimp dominate the faunal biomass of many headwater tropical streams: however, their role in community organization is unclear. Enclosure/exclosure experiments in a montane Puerto Rican stream examined direct and indirect effects of two dominant taxa of atyid (Atyidae) shrimp, Atya lanipes Holthuis and Xiphocaris elongata Guerin-Meneville. Both shrimp taxa caused significant reductions in sediment cover on rock substrata, reducing sedimentation and enhancing algal biovolume on clay tiles in cages. When tiles incubated in shrimp exclosures for 2 wks were placed outside of cages, atyid shrimp removed 100% of the sediment cover within a 30 min observation period. Atyid shrimp appear to play an important role in stream recovery after high discharge events by rapidly removing sediments and detritus deposited on benthic substrata in pools. We evaluated the mechanism by which A. lanipes influences algae and benthic insects by comparing patterns of algal biomass, taxonomic composition, and insect abundance between shrimp-exclusion and shrimp-presence treatments both with and without manual sediment removal. The shrimp exclusion treatment without manual sediment removal bad significantly lower algal biomass and greater sedimentation than all other treatments. The treatment in which shrimp were excluded but sediment was manually removed, however, accrued almost the same algal biovolume as the shrimp enclosure treatment, supporting the hypothesis that sediment removal enhances the biovolume of understory algal taxa. Algal community composition was similar between stream bottom bedrock exposed to natural densities of shrimp and all experimental treatments for both Atya and Xiphocaris: a diatom community strongly dominated (78–95%) by the adnate taxon, Achnanthes lanceolata Breb ex. Kutz. Atyid shrimp are important in determining the distribution and abundance of benthic insects through both direct and indirect effects. Sessile, retreat-building chironomid larvae (Chironomidae: Diptera) are negatively affected by both A. lanipes and X. elongata, through direct removal by foraging activities and/or indirectly through depression of sediment resources available to larvae for the construction of retreats. In constrast, the mobile grazer, Cloeodes maculipes (Baetidae: Ephemeroptera) was not adversely affected and atyid shrimp have the potential to exert positive indirect effects on this taxon by facilitating its exploitation of algal resources and/or through enhancement of understory algal food resources through sediment removal.
TL;DR: In this article, the differential quadrature method is used to analyse the deflection, buckling and free vibration behavior of anisotropic rectangular plates under various boundary conditions, and the roots of Chebyshev polynomials are used to obtain grid-point locations.
TL;DR: In this article, the authors provide an explicit test of the Gottfredson and Hirschi concept of self-control and its utility in explaining variation in interpersonal delinquency, theft, vandalism, legal substance use, illegal substance use and impnident behaviors.
TL;DR: Proximal and distal quality were equally effective in predicting children's development, each predicting two of six forms of development.
TL;DR: Data indicate that osteoblastic gene expression is detected in cells capable of undergoing adipocyte differentiation, consistent with the hypothesis that these cell lineages are interrelated.
Abstract: A growing body of data suggests that the bone marrow stroma contains a population of pluripotent cells capable of differentiating into adipocytes, osteoblasts, and lymphohematopoietic supporting cells. In this work, the murine stromal cell lines BMS2 and +/+ 2.4 have been examined as preadipocytes and adipocytes for evidence of osteoblastic gene expression. Adipocyte differentiation has been quantitated using fluorescence activated cell sorting. Within 7–10 days of adipocyte induction by treatment with glucocorticoids, indomethacin, and methylisobutylxanthine, between 40% to 50% of the cells contain lipid vacuoles and exhibit a characteristic adipocyte morphology. Based on immunocytochemistry, both the adipocytes and preadipocytes express a number of osteoblastic markers; these include alkaline phosphatase, osteopontin, collagen (I, III), bone sialoprotein II, and fibronectin. Based on biochemical assays, the level of alkaline phosphatase expression is not significantly different between preadipocyte and adipocyte cells. However, unlike rat cell lines, dexamethasone exposure causes a dose-dependent decrease in enzyme activity. The steady-state mRNA levels of the osteoblast associated genes varies during the process of adiopogenesis. The relative level of collagen I and collagen III mRNA is lower in adipocyte-induced cells when compared to the uninduced controls. Osteocalcin mRNA is detected in preadipocytes but absent in adipocytes. These data indicate that osteoblastic gene expression is detected in cells capable of undergoing adipocyte differentiation, consistent with the hypothesis that these cell lineages are interrelated. © 1993 Wiley-Liss, Inc.
TL;DR: The MS-IVs are less favorably inclined toward caring for the medically indigent than MS-Is, though these differences are apparent only for males.
Abstract: Objective. —To investigate the association between attitudes toward caring for the medically indigent and years of medical training. Design. —Questionnaire comparing attitudes of first-year medical students (MS-Is) and fourth-year medical students (MS-IVs). Setting. —Southwest medical school. Participants. —A total of 83 (67%) male and 41 (33%) female MS-I and 65 (73%) male and 24 (27%) female MS-IV volunteers. Main Outcome Measure. —Self-report, attitudinal scale developed for this study that provided a measure of overall attitudes, perceived societal expectations, physician/student responsibility, personal efficacy, and provision of basic services and expensive procedures. Results. —Overall attitudes were significantly less favorable for MS-IVs (95% confidence interval [CI], 99.6 to 106.2) than MS-Is (95% CI, 109.5 to 114.3,P .05). Except for physician/student responsibility, female medical students' attitudes were more favorable than those of males, regardless of class. Conclusions. —The MS-IVs are less favorably inclined toward caring for the medically indigent than MS-Is, though these differences are apparent only for males. Further research is needed to explore why females appear to be more resistant to attitude changes, and what educational interventions are necessary to better train physicians to respond to national health care issues. (JAMA. 1993;269:2519-2523)
TL;DR: In this paper, the authors proposed a strategy for incorporating threats of shame and embarrassment, along with the threat of legal sanctions, into a rational choice perspective on illegal behavior, and used that approach in an attempt to account for a reduction in self-reported drunk driving observed in a community between identical surveys conducted in 1982 and 1990.
Abstract: In a recent paper we proposed a strategy for incorporating threats of shame and embarrassment, along with the threat of legal sanctions, into a rational choice perspective on illegal behavior. In this paper we use that approach in an attempt to account for a reduction in self-reported drunk driving observed in a community between identical surveys conducted in 1982 and 1990. The interval between the two surveys was a period of intense legislative activity and moral crusading at the national and local levels. Our analysis indicates that the reduction in self-reported drunk driving in the community is primarily attributable to an increase in the threat of shame for this offense.
TL;DR: In this article, a three-dimensional numerical cloud model is used to investigate the influence of storm-relative environmental helicity (SREH) on convective storm structure and evolution, with a particular emphasis on the identification of ambient shear profiles that are conducive to the development of long-lived, strongly rotating storms.
Abstract: A three-dimensional numerical cloud model is used to investigate the influence of storm-relative environmental helicity (SREH) on convective storm structure and evolution, with a particular emphasis on the identification of ambient shear profiles that are conducive to the development of long-lived, strongly rotating storms. Eleven numerical simulations are made in which the depth and turning angle of the ambient vertical shear vector are varied systematically while maintaining a constant magnitude of the shear in the shear layer. In this manner, an attempt is made to isolate the effects of different environmental Felicities on storm morphology and show that the SREH and bulk Richardson number, rather than the mean shear in the low levels, determine the rotational characteristics and morphology of deep convection. The results demonstrate that storms forming in environments characterized by large SREH are longer-lived than those in less helical surroundings. Further, it appears that the storm-relat...
TL;DR: A comparison between solutions from simulations of a non-linear density current test problem was made in order to study the behavior of a variety of numerical methods as mentioned in this paper, and it was found that when the flow was adequately resolved, all of the numerical schemes produced solutions that contained the basic physics as well as most of the flow detail of the reference solution.
Abstract: A comparison between solutions from simulations of a non-linear density current test problem was made in order to study the behaviour of a variety of numerical methods. The test problem was diffusion-limited so that a grid-converged reference solution could be generated using high spatial resolution. Solutions of the test problem using several different resolutions were computed by the participants of the ‘Workshop on Numerical Methods for Solving Nonlinear Flow Problems’, which was held on 11–13 September 1990 at the National Center for Supercomputing Applications (NCSA). In general, it was found that when the flow was adequately resolved, all of the numerical schemes produced solutions that contained the basic physics as well as most of the flow detail of the reference solution. However, when the flow was marginally resolved, there were significant differences between the solutions produced by the various models. Finally, when the flow was poorly resolved, none of the models performed very well. While higher-order and spectral-type schemes performed best for adequately and marginally resolved flow, solutions made with these schemes were virtually unusable for poorly resolved flow. In contrast, the monotonic schemes provided the most coherent and smooth solutions for poorly resolved flow, however with noticeable amplitude and phase speed errors, even at finer resolutions.
TL;DR: The incidence and mortality rates in diabetic Oklahoma Indians were higher than those reported in Pima Indians and other diabetic populations and preventive action through education, foot care programs, and early detection of lesions must be intensified.
Abstract: Oklahoma Indians with NIDDM (n = 1012) underwent a baseline examination in 1972-1980. The incidence of and risk factors for first lower-extremity amputation were estimated. The mortality rates of amputees using data from 875 patients who had no previous history of amputation and who underwent follow-up examination between 1987 and 1991 are presented. The mean age of the 875 patients was 51.6 +/- 10.8 yr, and the mean duration of diabetes was 6.6 +/- 6.1 yr. After a mean follow-up time of 9.9 +/- 4.3 yr, the incidence rate of first LEA among diabetic Oklahoma Indians was 18.0/1000 person-yr. The incidence rate was two times higher in men than in women. In both sexes, significant risk factors (P < 0.05) were retinopathy and duration of diabetes. Fasting plasma glucose, use of insulin, and systolic blood pressure were significant for men only. For women, plasma cholesterol and diastolic blood pressure were additional risk factors. Compared with the mortality rate of 33.5/1000 person-yr among nonamputees, the rate among amputees was 55.5/1000 person-yr. The 5-yr survival rate after first amputation was 40.4%. For the amputees, the most common causes of death were diabetes (37.3%), cardiovascular disease (29.1%), and renal disease (7.3%). The incidence and mortality rates in diabetic Oklahoma Indians were higher than those reported in Pima Indians and other diabetic populations. To lower the incidence of lower-extremity amputation in this high-risk population, preventive action through education, foot care programs, and early detection of lesions must be intensified.
TL;DR: The marked variations in incidence and inverse relationship between incidence and survival could be due to true variation in risk among the populations reported (ie, some populations may be older or sicker than others).
TL;DR: Fifty patients who underwent isolated arthroscopic par tial meniscectomy with a minimum followup of 5 years were analyzed retrospectively, and it was felt that Fairbank's changes were significant and indicative of abnormal stress transfer to articular cartilage and bone.
Abstract: Fifty patients who underwent isolated arthroscopic par tial meniscectomy with a minimum followup of 5 years were analyzed retrospectively. To analyze the factors associated with a satisfactory or an unsatisfactory clin ical result, we looked at the patient's age, duration of symptoms, type of meniscal lesion, and articular carti lage abnormalities. The patients were graded with a functional knee score (Lysholm-Gillquist), and activity level before surgery and at followup was determined. The data also included radiographic evaluation of 29 of the 50 patients. Tibiofemoral alignment was measured, and osteoarthritic changes were graded and correlated with the type of meniscal abnormality and functional result.Eighty-two percent of our patients had satisfactory knee function, and the activity level was maintained. The factors associated with a satisfactory result after a partial meniscectomy included age less than 40 years, symptoms less than 12 months duration, type of tear, and chondromalacia less than grad...
TL;DR: Different developmental programs are invoked in both the egg and central cells by the fusion of each with a sperm cell in an event characteristic of flowering plants known as “double fertilization.”
Abstract: Flowering plant reproduction is unusual in many features, as evidenced by the different topics discussed in this issue of THE PLANT CELL. The egg cell of flowering plants in particular displays several unique features. First, the egg cell is an integral part of the several thousands of cells forming the ovule, and it cannot be released without the aid of enzymes or microdissection. The egg cell appears to be part of a functional assemblage of cells that are fragile in isolation. Surrounding the egg cell in situ are the two synergids (collectively forming the egg apparatus) and the adjacent central cell, as shown in Figure 1. These are almost always derived from the same initial meiotic cell as the egg cell. The surrounding cells appear to provide nutrition for the egg cell and are involved in the positioning of the sperm cells to the precise site where gametic fusion occurs. Different developmental programs are invoked in both the egg and central cells by the fusion of each with a sperm cell in an event characteristic of flowering plants known as “double fertilization.” During this event, one sperm nucleus fuses with the egg nucleus to form the zygote, whereas the other sperm nucleus fuses with the two (or more) central cell nuclei, resulting in the formation of the nutritive endosperm. The developmental potential, biochemical identity, and char
TL;DR: Analytical models are used to compare the rates at which an isolated fracture and vertical, parallel fracture sets in hydrothermal upflow zones can be closed by silica precipitation and thermoelastic stress.
Abstract: Analytical models are used to compare the rates at which an isolated fracture and vertical, parallel fracture sets in hydrothermal upflow zones can be closed by silica precipitation and thermoelastic stress. Thermoelastic sealing is an order of magnitude faster than sealing by silica precipitation. In vertical fracture sets, both the amount of silica precipitation resulting from cooling and the total thermal expansion of the country rock may be insufficient to seal cracks at depth. These crack systems may ultimately close because the pressure dependence of silica solubility maintains precipitation during upflow even after the temperature gradient vanishes.
TL;DR: This article found that evangelical/fundamentalist Protestants are more inclined to attribute crime to offenders' dispositional characteristics than to situational factors, and they are expected to be more punitive than members of other groups.
Abstract: The increased punitiveness in the criminal justice system, stimulated at least to some extent by public opinion, has coincided with the revival of Protestant evangelicalism and fundamentalism and with their followers' active involvement in politics and policy debates. Previous research on the determinants of preferred justice policies in the public either ignored religion or relied on a simple distinction among Protestants, Catholics, and Jews. The present study argues that evangelical/fundamentalist Protestants are more inclined to attribute crime to offenders' dispositional characteristics than to situational factors. Consequently they are expected to be more punitive than members of other groups. Survey data from a sample of adults in a southwestern city reveal greater punitiveness among evangelical/fundamentalist Protestants on four of five policy issues, including support for the death penalty both for adults and for juveniles.
TL;DR: This paper introduces a new class of interconnection scheme based on the Cayley graph of the alternating group, and it is shown that this class of graphs are edge symmetric and 2-transitive.
Abstract: This paper introduces a new class of interconnection scheme based on the Cayley graph of the alternating group. It is shown that this class of graphs are edge symmetric and 2-transitive. We then describe an algorithm for (a) packet routing based on the shortest path analysis, (b) finding a Hamiltonian cycle, (c) ranking and unranking along the chosen Hamiltonian cycle, (d) unit expansion and dilation three embedding of a class of two-dimensional grids, (e) unit dilation embedding of a variety of cycles, and (f) algorithm for broadcasting messages. The paper concludes with a short analysis of contention resulting from a typical communication scheme. Although this class of graphs does not possess many of the symmetry properties of the binary hypercube, with respect to the one source broadcasting, these graphs perform better than does a hypercube, and with respect to the contention problem, these graphs perform better than do the star graphs and are close to the hypercube. © 1993 by John Wiley & Sons, Inc.