Showing papers by "University of Texas at Austin published in 1988"

Social relationships and health.

Abstract: Recent scientific work has established both a theoretical basis and strong empirical evidence for a causal impact of social relationships on health. Prospective studies, which control for baseline health status, consistently show increased risk of death among persons with a low quantity, and sometimes low quality, of social relationships. Experimental and quasi-experimental studies of humans and animals also suggest that social isolation is a major risk factor for mortality from widely varying causes. The mechanisms through which social relationships affect health and the factors that promote or inhibit the development and maintenance of social relationships remain to be explored.

A field study of the software design process for large systems

Abstract: The problems of designing large software systems were studied through interviewing personnel from 17 large projects. A layered behavioral model is used to analyze how three of these problems—the thin spread of application domain knowledge, fluctuating and conflicting requirements, and communication bottlenecks and breakdowns—affected software productivity and quality through their impact on cognitive, social, and organizational processes.

Learning to read and write: A longitudinal study of 54 children from first through fourth grades.

Abstract: My research focused on literacy development in children through fourth grade and followed an earlier study (Juel, Griffith, & Gough, 1986). The Simple View of reading and writing received support in this earlier study and was examined in my current research. Of particular concern were these questions: Do the same children remain poor readers year after year? Do the same children remain poor writers year after year? What skills do the poor readers lack? What skills do the poor writers lack? What factors seem to keep poor readers from improving? What factors seem to keep poor writers from improving? The probability that a child would remain a poor reader at the end of fourth grade if the child was a poor reader at the end of first grade was .88. Early writing skill did not predict later writing skill as well as early reading ability predicted later reading ability. Children who became poor readers entered first grade with little phonemic awareness. By the end of fourth grade, the poor readers had still not achieved the level of decoding skill that the good readers had achieved at the beginning of second grade. Good readers read considerably more than the poor readers both in and out of school, which appeared to contribute to the good readers' growth in some reading and writing skills (e.g., in ideas for stories). Poor readers tended to become poor writers. The Simple View received support in accounting for reading and writing development through fourth grade. This study examined the development of literacy in one elementary school with a large minority, low socioeconomic status population. The reading and writing development of 54 children was followed as they progressed from first through fourth grade. This in-depth examination of literacy acquisition in a microcosm of at-risk children attempted to answer the following questions: Do the same children remain poor readers year after year? Do the same children remain poor writers year after year? What skills do the poor readers lack?

On cognitive busyness: When person perceivers meet persons perceived.

Abstract: Person perception includes three sequential processes: categorization (what is the actor doing?), characterization (what trait does the action imply?), and correction (what situational constraints may have caused the action?). We argue that correction is less automatic (i.e., more easily disrupted) than either categorization or characterization. In Experiment 1, subjects observed a target behave anxiously in an anxiety-provoking situation. In Experiment 2, subjects listened to a target read a political speech that he had been constrained to write. In both experiments, control subjects used information about situational constraints when drawing inferences about the target, but cognitively busy subjects (who performed an additional cognitive task during encoding) did not. The results (a) suggest that person perception is a combination of lower and higher order processes that differ in their susceptibility to disruption and (b) highlight the fundamental differences between active and passive perceivers. Many of us can recall a time when, as students, we encountered a professor at a party and were surprised to find that he or she seemed a very different sort of person than our classroom experience had led us to expect. In part, such discrepant impressions reflect real discrepancies in behavior: Professors may display greater warmth or less wit at a party than they do in the classroom. However, just as the object of perception changes across situations, so too does the perceiver. As passive perceivers in a classroom, we are able to observe a professor without concerning ourselves with the mechanics of social interaction. At a party, however, we are active perceivers , busy managing our impressions, predicting our partner's behavior, and evaluating alternative courses of action. Of all the many differences between active and passive perceivers, one seems fundamental: Active perceivers, unlike passive perceivers, are almost always doing several things at once ( Gilbert, Jones, & Pelham, 1987 ; Gilbert & Krull, 1988 ; Jones & Thibaut, 1958 ).

The Beliefs about Language Learning of Beginning University Foreign Language Students

Abstract: liefs about how languages are learned.1 Definite viewpoints on the best techniques for learning a language, the "right" age to begin language study, and the nature of the language learning process are the subject of airline magazine articles, Sunday supplement advertisements, and cocktail party small-talk. Many people apparently believe, for example, that second language fluency can be obtained with relatively little effort. In the course of a review of the time

Impact of exchange variables on exit, voice, loyalty, and neglect: An integrative model of responses to declining job satisfaction.

Abstract: This research offers a new theory predicting the effects of three exchange variables, job satisfaction, investment size, and quality of alternatives, on four general responses to dissatisfaction—exit, voice, loyalty, and neglect. Three studies designed to test model predictions' received good support. High satisfaction and investment encouraged voice and loyalty and discouraged exit and neglect. Satisfaction and investment interacted, with variations in investment most strongly promoting voice given high satisfaction. Better alternatives encouraged exit and voice and discouraged loyalty. However, there was no link between alternatives and neglect.

A Computational Logic Handbook

Abstract: Contains a precise and complete description of the computational logic develo by the authors; will serve also as a reference guide to the associated mechanical theorem proving system. Annotation copyright Book News, Inc. Portland, Or.

Strategic Human Resources Management: A Review of the Literature and a Proposed Typology

Abstract: Past efforts to relate the management of human resources to a firm's business strategy have taken three approaches: matching managerial style or personnel activities with strategies, forecasting manpower requirements given certain strategic objectives or environmental conditions, and presenting means for integrating human resource management into the overall effort to match strategy and structure. In this article, the literature on each of these approaches is reviewed, and a typology is presented that posits a reciprocal interdependence between a firm's business strategy and its human resources strategy Implications for research and practice are discussed.

Directional selection and the evolution of breeding date in birds

Abstract: In many bird species, those pairs that breed earlier in the season have higher reproductive success than those that breed later. Since breeding date is known to be heritable, it is unclear why it does not evolve to an earlier time. Under assumptions outlined by Fisher, a model is developed that shows how breeding date may have considerable additive genetic variance, appear to be under directional selection, and yet not evolve. These results provide a general explanation for a persistent correlation of fitness with a variety of traits in natural populations.

Comparison of the Cellular Pharmacokinetics and Toxicity of 2′,2′-Difluorodeoxycytidine and 1-β-d-Arabinofuranosylcytosine

Abstract: 2',2'-Difluorodeoxycytidine (dFdC) is a new deoxycytidine analogue with good activity against human leukemic cell lines and murine solid tumors, while the activity of 1-beta-D-arabinofuranosylcytosine (ara-C) is established in experimental systems and for the treatment of human adult leukemia. This study compared the cellular metabolism and cytotoxic properties of dFdC and ara-C in Chinese hamster ovary cells. In wild-type cells, dFdC was significantly more cytotoxic than ara-C after both 4- and 18-h incubations. The 5'-triphosphate of dFdC (dFdCTP) was the major cellular metabolite (85-90%), reaching cellular concentrations up to 20-fold greater than those observed for ara-C 5'-triphosphate at equimolar concentrations of the parent drug. A deoxycytidine kinase-deficient mutant neither accumulated dFdCTP nor showed any cytotoxic response up to drug concentrations of 100 microM. The cytotoxicity of dFdC could be competitively reversed by deoxycytidine further suggesting that dFdC, like ara-C, required phosphorylation by deoxycytidine kinase for biological activity. Several explanations for the different cellular accumulation of the drug triphosphates were established: (a) nucleoside transport studies demonstrated that the membrane permeation of dFdC was 65% more rapid than that of ara-C; (b) deoxycytidine kinase had a higher affinity for dFdC (Km = 3.6 microM) than for ara-C (Km = 8.8 microM), while the Km for deoxycytidine was 1.4 microM; (c) the elimination of intracellular dFdCTP was biphasic with t1/2 alpha = 3.9 and t1/2 beta greater than 16 h while the degradation of ara-CTP was monophasic and significantly faster (t1/2 = 0.7 h). The comparatively long half-life of dFdCTP was related to the prolonged inhibition of DNA synthesis after removal of exogenous nucleoside. Together these factors contribute to the more potent cytotoxicity of dFdC compared with ara-C.

Organ specificity of tumor metastasis: role of preferential adhesion, invasion and growth of malignant cells at specific secondary sites

Abstract: The locations of distant secondary tumors in many clinical cancers and animal tumors are nonrandom, and their distributions cannot be explained by simple anatomical or mechanical hypotheses based on the simple lodgment or trapping of tumor cell emboli in the first capillary bed encountered. Evidence from certain experimental tumor systems supports Paget's ‘seed and soil’ hypothesis on the nonrandom distributions of metastases, in which the unique properties of particular tumor cells (‘seeds’) and the different characteristics of each organ microenvironment (‘soil’) collectively determine the organ preference of metastasis. Experimentally, differential tumor cell adhesion to organ-derived microvessel endothelial cells and organ parenchymal cells, differential invasion of basement membranes and organ tissues, and differential responses to organ-derived growth-stimulatory and-inhibitory factors all appear to be important determinants in explaining the organ preference of metastasis. Each tumor system may achieve organ specificity because of its own unique set of multiple metastasis-associated properties and responses to host microenvironments. As neoplasms progress to more highly malignant states multisite metastases are more likely and organ-specific metastases may be masked or circumvented owing to stochastic events, tumor cell diversification, host selection processes, and increased production of tumor autocrine molecules that may modulate adhesion, invasion, growth, and other properties important in metastasis. The importance of each of these properties, however, appears to vary considerably among different metastatic tumor systems. These and other tumor cell and host properties may eventually be used to predict and explain the unique metastastic distributions to certain human malignancies.

Subduction-channel model of prism accretion, melange formation, sediment subduction, and subduction erosion at convergent plate margins: 2. Implications and discussion

Abstract: The subduction-channel model predicts five geologically and geophysically distinctive types of convergent plate margin. They differ primarily in the proportions of incoming sediment and upflowing melange offscraped and underplated near the toe of the overriding block. The model predicts complex patterns of uplift or subsidence of the forearc region due to differential underplating or subduction erosion and to initiation or cessation of melange upflow. It shows how subduction speed, sediment input, and pressure gradient along the channel govern the general distribution and magnitude of subduction-zone earthquakes. It can predict the upward trajectories of exotic blueschist or serpentinized peridotite blocks that become entrained in the upwelling melange; and it suggests mechanisms by which much larger tracts of coherent blueschist can be raised to shallower levels. It predicts characteristic structural and metamorphic histories for geologic units accreted during steady-state subduction, showing for example, that offscraped materials undergo subhorizontally-directed compression during final dewatering and accretion, whereas underplated ones undergo large simple shear. It gives the maximum depths reached by upwelled melange, which bear significantly on the metamorphic changes observed in them. It predicts large-scale melange diapirism in certain rare cases, in which the normally adverse pressure gradient is reversed in a short reach of the channel, as at Barbados Island. Finally, it explains why pelagic sediments are seldom found in accretionary complexes and gives insight into the factors controlling what portion of the incoming sediment, and the10Be and other tracers it carries, will reach the region of volcanic-arc magmagenesis.

Management of stage III primary breast cancer with primary chemotherapy, surgery, and radiation therapy.

Abstract: One hundred seventy-four evaluable patients with noninflammatory Stage III (both operable and inoperable) breast cancer were treated with a combined modality strategy between 1974 and 1985. All patients received combination chemotherapy with 5-fluorouracil, Adriamycin (doxorubicin), and cyclophosphamide (FAC) as their initial form of therapy. After three cycles of chemotherapy, local treatment in the form of a total mastectomy with axillary dissection, or radiotherapy, or both, was completed. Subsequently, adjuvant chemotherapy was continued. There were 48 patients with Stage IIIA, and 126 patients with Stage IIIB disease. A complete remission was achieved in 16.7% of the patients, and 70.7% achieved a partial remission after the initial three cycles of FAC. The complete response rate was higher for patients with Stage IIIA, than for patients with Stage IIIB disease. All but six of the 174 patients treated were rendered disease-free after induction chemotherapy and local treatment. The median follow-up of this group of patients is 59 months. The 5-year disease-free survival rates were 84% for patients with Stage IIIA, and 33% for patients with Stage IIIB disease. The 5-year survival rate for, patients with Stage IIIA was 84%, and for patients with Stage IIIB 44%. At 10 years, 56% of patients with Stage IIIA and 26% of patients with Stage IIIB disease are projected to be alive. Younger patients, and those with estrogen receptor-positive tumors, had a trend for better survival than older patients and those with estrogen receptor-negative tumors. The quality of response to induction chemotherapy correlated prominently with prognosis, as did compliance with treatment. Twenty-six patients (15.3%) had locoregional recurrence. This multidisciplinary approach to locally advanced breast cancer rendered most patients disease-free and produced an excellent local control rate. Modifications of this treatment strategy may result in further improvement of survival rates.

Definition, diagnosis, and origin of Mammalia

Abstract: Mammalia is defined by its ancestry as the taxon originating with the most recent common ancestor of extant Monotremata and Theria. To diagnose Mammalia as so defined, 176 character transformations...

Laser-induced damage on single-crystal metal surfaces

Abstract: Laser-induced damage morphologies and the accumulation dependence of damage on single-crystal metal surfaces have been observed under Q-switched 1064-nm Nd:YAG laser irradiation at 10-nsec pulses. Several different damage morphologies were observed: slip-line formation, ripple patterns, flat melting, and boiling. Damage probability versus fluence curves and accumulation curves are plotted to investigate damage behavior as it correlates with morphology. Flat-melting damage was observed near the 50% damage fluence on chemically polished copper surfaces, and slip lines were found near the 50% damage fluence on electropolished aluminum surfaces. Surface defects produced during sample preparation greatly influenced the damage threshold of copper because of its high melting threshold. Accumulation curves showed different damage behavior for crystals of different orientation. Accumulation was the largest on (111) Cu and Al surfaces, and the single-shot damage threshold of these surfaces was less than the other crystal orientations for both Cu and Al. The threshold reduction in accumulation follows the equation FN = F1NS−1, where FN is the N-pulse damage threshold, N is the pulse number, and S is the slope of the accumulation curve. Accumulation appears to be the result of the storage cycle of thermal stress–strain energy induced by a laser pulse. The total strain energy induced by N laser pulses is proportional to N1/3 for the measured values of S, which is 0.92.

Muscle glycogen synthesis after exercise: effect of time of carbohydrate ingestion

Abstract: The time of ingestion of a carbohydrate supplement on muscle glycogen storage postexercise was examined. Twelve male cyclists exercised continuously for 70 min on a cycle ergometer at 68% VO2max, interrupted by six 2-min intervals at 88% VO2max, on two separate occasions. A 25% carbohydrate solution (2 g/kg body wt) was ingested immediately postexercise (P-EX) or 2 h postexercise (2P-EX). Muscle biopsies were taken from the vastus lateralis at 0, 2, and 4 h postexercise. Blood samples were obtained from an antecubital vein before and during exercise and at specific times after exercise. Muscle glycogen immediately postexercise was not significantly different for the P-EX and 2P-EX treatments. During the first 2 h postexercise, the rate of muscle glycogen storage was 7.7 mumol.g wet wt-1.h-1 for the P-EX treatment, but only 2.5 mumol.g wet wt-1.h-1 for the 2P-EX treatment. During the second 2 h of recovery, the rate of glycogen storage slowed to 4.3 mumol.g wet wt-1.h-1 during treatment P-EX but increased to 4.1 mumol.g wet wt-1.h-1 during treatment 2P-EX. This rate, however, was still 45% slower (P less than 0.05) than that for the P-EX treatment during the first 2 h of recovery. This slower rate of glycogen storage occurred despite significantly elevated plasma glucose and insulin levels. The results suggest that delaying the ingestion of a carbohydrate supplement post-exercise will result in a reduced rate of muscle glycogen storage.

Determinants of endurance in well-trained cyclists

Abstract: Fourteen competitive cyclists who possessed a similar maximum O2 consumption (VO2 max; range, 4.6–5.0 l/min) were compared regarding blood lactate responses, glycogen usage, and endurance during su...

Admixture as a tool for finding linked genes and detecting that difference from allelic association between loci

Abstract: Admixture between genetically different populations may produce gametic association between gene loci as a function of the genetic difference between parental populations and the admixture rate. This association decays as a function of time since admixture and the recombination rate between the loci. Admixture between genetically long-separated human populations has been frequent in the centuries since the age of exploration and colonization, resulting in numerous hybrid descendant populations today, as in the Americas. This represents a natural experiment for genetic epidemiology and anthropology, in which to use polymorphic marker loci (e.g., restriction fragment length polymorphisms) and disequilibrium to infer a genetic basis for traits of interest. In this paper we show that substantial disequilibrium remains today under widely applicable situations, which can be detected without requiring inordinately close linkage between trait and marker loci. Very disparate parental allele frequencies produce large disequilibrium, but the sample size needed to detect such levels of disequilibrium can be large due to the skewed haplotype frequency distribution in the admixed population. Such situations, however, provide power to differentiate between disequilibrium due just to population mixing from that due to physical linkage of loci--i.e., to help map the genetic locus of the trait. A gradient of admixture levels between the same parental populations may be used to test genetic models by relating admixture to disequilibrium levels.

A Deterministic Inventory System with an Inventory-Level-Dependent Demand Rate

Abstract: This analysis is concerned with the continuous, deterministic case of an inventory system in which the demand rate of an item is of a polynomial functional form, dependent on the inventory level. Differential and integral calculus are used to find the inventory function with respect to time. From this, the objective function (to maximize average profit per unit time) is developed. For the continuous, multiperiod situation, a non-linear programming algorithm—separable programming—is utilized to determine the optimal order level (the quantity to order up to) and the order point (the quantity at which an order is placed). A numeric example and a sensitivity analysis are also presented.