Showing papers by "Temple University published in 1997"

Role of Fatty Acids in the Pathogenesis of Insulin Resistance and NIDDM

Abstract: Evidence is reviewed that free fatty acids (FFAs) are one important link between obesity and insulin resistance and NIDDM. First, plasma FFA levels are elevated in most obese subjects. Second, physiological elevations in plasma FFA concentrations inhibit insulin stimulated peripheral glucose uptake in a dose-dependent manner in normal controls and in patients with NIDDM. Two possible mechanisms are identified: 1) a fat-related inhibition of glucose transport or phosphorylation, which appears after 3-4 h of fat infusion, and 2) a decrease in muscle glycogen synthase activity, which appears after 4-6 h of fat infusion. Third, FFAs stimulate insulin secretion in nondiabetic individuals. Some of this insulin is transmitted in the peripheral circulation and is able to compensate for FFA-mediated peripheral insulin resistance. FFA-mediated portal hyperinsulinemia counteracts the stimulation of FFAs on hepatic glucose production (HGP) and thus prevents hepatic glucose overproduction. We speculate that, in obese individuals who are genetically predisposed to develop NIDDM, FFAs will eventually fail to promote insulin secretion. The stimulatory effect of FFAs on HGP would then become unchecked, resulting in hyperglycemia. Hence, continuously elevated levels of plasma FFAs may play a key role in the pathogenesis of NIDDM in predisposed individuals by impairing peripheral glucose utilization and by promoting hepatic glucose overproduction.

Lexical Access in Aphasic and Nonaphasic Speakers

Abstract: An interactive 2-step theory of lexical retrieval was applied to the picture-naming error patterns of aphasic and nonaphasic speakers. The theory uses spreading activation in a lexical network to accomplish the mapping between the conceptual representation of an object and the phonological form of the word naming the object. A model developed from the theory was parameterized to fit normal error patterns. It was then "lesioned" by globally altering its connection weight, decay rates, or both to provide fits to the error patterns of 21 fluent aphasic patients. These fits were then used to derive predictions about the influence of syntactic categories on patient errors, the effect of phonology on semantic errors, error patterns after recovery, and patient performance on a singleword repetition task. The predictions were confirmed. It is argued that simple quantitative alterations to a normal processing model can explain much of the variety among patient patterns in naming.

Therapy for youths with anxiety disorders: a second randomized clinical trial.

Abstract: Ninety-four children (aged 9-13 years) with anxiety disorders were randomly assigned to cognitive behavioral treatment or waiting-list control. Outcomes were evaluated using diagnostic status, child self-reports, parent and teacher reports, cognitive assessment and behavioral observation: maintenance was examined using 1-year follow-up data. Analyses of dependent measures indicated significant improvements over time, with the majority indicating greater gains for those receiving treatment. Treatment gains returned cases to within nondeviant limits (i.e., normative comparisons) and were maintained at 1-year follow-up. Client age and comorbid status did not moderate outcomes. A preliminary examination of treatment segments suggested that the enactive exposure (when it follows cognitive-educational training) was an active force in beneficial change. Discussion includes suggestions for future research.

Empirical Performance of Alternative Option Pricing Models

Abstract: Substantial progress has been made in extending the Black-Scholes model to incorporate such features as stochastic volatility, stochastic interest rates and jumps.On the empirical front, however, it is not yet known whether and by how much each generalized feature will improve option pricing and hedging performance. This paper fills this gap by first developing an implementable option model in closed form that allows volatility, interest rates and jumps to bestochastic and that is parsimonious in the number of parameters. The model includes many known ones as special cases. Delta-neutral and single-instrument minimum-variance hedging strategies are derived analytically. Using S&P 500 options, we examine a set of alternative models from three perspectives: (1) internal consistency of implied parameters/volatility with relevant time-series data, (2)out-of-sample pricing and (3) hedging performance. The models of focus include the benchmark Black-Scholes formula and the ones that respectively allow for (i) stochastic volatility, (ii) both stochastic volatility and stochastic interest rates, and (iii) stochastic volatility and jumps.Overall, incorporating both stochastic volatility and random jumps produces the best pricing performance and the most internally-consistent implied-volatility process. Its implied volatility does not "smile" across moneyness. But, for hedging, adding either jumps or stochastic interest rates does not seem to improve performance any further once stochastic volatility is taken into account.

Parenting Styles, Adolescents' Attributions, and Educational Outcomes in Nine Heterogeneous High Schools

Abstract: This article examined the contemporaneous and predictive relations between parenting styles, adolescents' attributions, and 4 educational outcomes. Data were collected from adolescents attending 6 high schools in California and 3 high schools in Wisconsin during the 1987-1988 and 1988-1989 school years. The results of path analyses partially confirmed the central hypotheses. Adolescents who perceived their parents as being nonauthoritative were more likely than their peers to attribute achievement outcomes to external causes or to low ability. Furthermore, the higher the proportion of dysfunctional attributions made for academic successes and failures, the lower the levels of classroom engagement and homework 1 year later. Although adolescents' attributional style provided a bridge between parenting style and 2 educational outcomes, it did not fully explain the impact of parenting on those outcomes. Additional analyses within gender and ethnic subgroups reinforced the overall pattern of findings observed within the entire sample.

The Two Faces of Adam: Ambivalent Sexism and Polarized Attitudes Toward Women

Abstract: Two studies using Peter Glick and Susan Fiske's Ambivalent Sexism Inventory examined sexist men's attitudes toward women. The authors hypothesized that ambivalent sexist (as compared with nonsexist) men would habitually classify women into polarized subgroups (those they put on a "pedestal" and those they place in the "gutter"). Study 1 revealed that ambivalent sexism predicted greater polarization in men's evaluations of spontaneously generated female subtypes. Study 2 demonstrated that the negative component of sexist ambivalence (hostile sexism) predicted less favorable evaluations of women in a nontraditional role (career women), whereas the subjectively positive component of sexist ambivalence (benevolent sexism) predicted favorable feelings toward women in a traditional role (homemakers). Implications for the nature of sexist ambivalence (and other forms of ambivalent prejudice) are discussed.

The empirical evaluation of language teaching materials

Abstract: This article distinguishes two types of materials evaluation: a predictive evaluation designed to make a decision regarding what materials to use, and a retrospective evaluation designed to examine materials to use, and a retrospective evaluation designed to examine materials that have actually been used. Retrospective evaluations can be impressionistic or empirical. It is suggested that one way in which teachers can conduct empirical evaluations is by investigating specific teaching tasks. A procedure for conducting a task evaluation is described. Finally, it is suggested that task evaluations constitute a kind of action research that can contribute to reflective practice in teaching.

Patients' expectations and satisfaction with total hip arthroplasty

Abstract: Although there have been many studies focusing on the increasingly important assessment of patients' satisfaction, few studies have specifically addressed this tissue for total hip arthroplasty (THA). The goals of this study were to measure patients' satisfaction with THA and to evaluate the relationships of expectations and outcome to patients' satisfaction. A total of 180 patients were surveyed 2 to 3 years after THA about their experiences with THA. Patients cited 45 different expectations, which were grouped into five categories reflecting improvement in pain, walking, psychological state, essential activities, and nonessential activities. Overall, 89% of patients were satisfied with the results of surgery. Lower rates of satisfaction were found in patients who had a better preoperative condition (as measured by the surgeons with The Hospital for Special Surgery Hip Scale), in patients who expected improvement in nonessential activities, and in patients who reported worse postoperative condition (as measured by self-assessment with the Hip Rating Questionnaire and the Medical Outcomes Study Short-form General Health Survey). Patients were also asked how they came to THA. Nearly 50% of patients were first referred to an orthopaedist by family or friends or based on their own knowledge. Seventy-four percent either had subsequently referred others for THA or would have done so if they knew someone with hip pain. This study demonstrates that satisfaction with THA is a complex phenomenon, affected by expectations, outcome, and what patients know about the procedure from their community network. A better understanding of THA satisfaction will enable better future selection of patients and an additional dimension of outcome, both of which are important to patients and payers.

Nitrogen Balance in and Export from an Agricultural Watershed

Abstract: Surface water nitrate (NO 3 - ) pollution from agricultural production is well established, although few studies have linked field N budgets, NO 3 - loss in tile drained watersheds, and surface water NO 3 - loads This study was conducted to determine field sources, transport, and river export of NO 3 - from an agricultural watershed The Embarras River watershed at Camargo (48 173 ha) in east-central Illinois was investigated The watershed is a tile-drained area of fertile Mollisols (typical soil is Drummer silty clay loam, a fine-silty, mixed mesic Typic Haplaquoll) with primary cropping of maize (Zea mays L) and soybean (Glycine max L) Agricultural field N sources and sinks, tile drainage NO 3 - concentrations and fluxes, and river NO 3 - export were estimated for the entire watershed Large pools of inorganic N were present following each harvest of maize and soybean (average of 3670 Mg N yr -1 over a 6-yr period) The source of most of the inorganic N was divided between N fertilizer and soil mineralized N High concentrations of NO 3 were found in four monitored drainage tiles (5-49 mg N L '), and tile concentrations of NO 3 - were synchronous with Embarras River NO 3 - concentrations High flow events contributed most of the yearly NO 3 - loss (247 kg N ha -1 yr -1 ) from tile drained fields in the 1995 water year (1 Oct, 1994 through 30 Sept 1995) where high rainfall events occurred in a low overall precipitation year (in one tile 21% of the annual load was exported in 1 d) During the 1996 water year, NO 3 - export in tiles was much higher (442 kg N ha -1 yr -1 ) due to greater precipitation, and individual days were less important On average, about 49% (average of 1688 Mg N yr ' over a 6-yr period) of the field inorganic N pool was estimated to be leached through drain tiles and seepage and was exported by the Embarras River, although depending on weather and field N balances this ranged from 25 to 85% of the field N balance over the 6-yr period It seems likely that agricultural disturbance (high mineralization inputs of N) and N fertilization combined with tile drainage contributed significantly to NO, export in the Embarras River

Selective Suppression of Interleukin-12 Induction after Macrophage Receptor Ligation

Abstract: Interleukin (IL)-12 is a monocyte- and macrophage-derived cytokine that plays a crucial role in both the innate and the acquired immune response. In this study, we examined the effects that ligating specific macrophage receptors had on the induction of IL-12 by lipopolysaccharide (LPS). We report that ligation of the macrophage Fcγ, complement, or scavenger receptors inhibited the induction of IL-12 by LPS. Both mRNA synthesis and protein secretion were diminished to near-undetectable levels following receptor ligation. Suppression was specific to IL-12 since IL-10 and tumor necrosis factor-α (TNF-α) production were not inhibited by ligating macrophage receptors. The results of several different experimental approaches suggest that IL-12 downregulation was due to extracellular calcium influxes that resulted from receptor ligation. First, preventing extracellular calcium influxes, by performing the assays in EGTA, abrogated FcγR-mediated IL-12(p40) mRNA suppression. Second, exposure of macrophages to the calcium ionophores, ionomycin or A23187, mimicked receptor ligation and inhibited IL-12(p40) mRNA induction by LPS. Finally, bone marrow–derived macrophages from FcR γ chain–deficient mice, which fail to flux calcium after receptor ligation, failed to inhibit IL-12(p40) mRNA induction. These results indicate that the calcium influxes that occur as a result of receptor ligation are responsible for inhibiting the induction of IL-12 by LPS. Hence, the ligation of phagocytic receptors on macrophages can lead to a dramatic decrease in IL-12 induction. This downregulation may be a way of limiting proinflammatory responses of macrophages to extracellular pathogens, or suppressing the development of cell-mediated immunity to intracellular pathogens.

Litigation Risk and Auditor Resignations

Abstract: Litigation against auditors has increased dramatically in recent years. Auditors can offset litigation risk in a number of ways, including improved audit quality and planning, increases in audit fees and increases in the issuance of modified opinions. Auditors can also adjust their client portfolios by becoming more selective in their choice of new clients and by withdrawing from high-risk engagements. We test the hypothesis that litigation risk motivates auditor resignations by comparing resignation companies with two groups of client companies that dismissed their auditors: one matched with the resignation companies on industry and year, and the other matched on year alone. We find resignation companies differ from dismissal companies along dimensions that capture the probability of litigation: financial distress, variance of abnormal returns, auditor independence, tenure and a modified (particularly going-concern) opinion. We also construct a litigation proxy based on a prior litigation-prediction model and find that the proxy is positively associated with the probability that the auditor will resign rather than be dismissed from the engagement. Our analysis is consistent with concerns expressed by the accounting profession that litigation pressures lead to the withdrawal of audit services for a segment of the market.

The Simes Method for Multiple Hypothesis Testing with Positively Dependent Test Statistics

Abstract: The Simes method for testing intersection of more than two hypotheses is known to control the probability of type I error only when the underlying test statistics are independent. Although this method is more powerful than the classical Bonferroni method, it is not known whether it is conservative when the test statistics are dependent. This article proves that for multivariate distributions exhibiting a type of positive dependence that arise in many multiple-hypothesis testing situations, the Simes method indeed controls the probability of type I error. This extends some results established very recently in the special case of two hypotheses.

School Delinquency and the School Social Bond

Abstract: Using data from a sample of 754 middle school students in Grades 7 and 8, this article examines the independent effects of the four components of the school social bond—school commitment, attachment to school, school involvement, and belief in school rules—on school crime, school misconduct, and school nonattendance. The results suggest that personal background, family involvement in schooling, and ability grouping have differential effects on the school bond components. Also, an examination of the independent effects of the four components of the school social bond suggests that certain components are more important than others in controlling different types of school delinquency. These results suggest that the school social bond is an important intervening mechanism that helps to explain the effects of certain predictor variables on school crime, school misconduct, and nonattendance in middle schools.

Efficacy and safety of enoxaparin versus unfractionated heparin for prevention of deep vein thrombosis in elective cancer surgery: A double-blind randomized multicentre trial with venographic assessment

Abstract: Efficacy and safety of enoxaparin versus unfractionated heparin for prevention of deep vein thrombosis in elective cancer surgery: a double-blind randomized multicentre trial with venographic assessme

Tillage-induced soil carbon dioxide loss from different cropping systems

Abstract: Tillage of soils often decreases soil organic matter content and increases the flux of carbon dioxide (CO 2 ) from soils. Our objectives were (1) to measure short-term, tillage-induced soil CO 2 flux from different cropping systems using two instruments, a soil chamber (about 10 −3 m 3 ) and a canopy chamber (3.25 m 3 ), and (2) to examine the interactions between cumulative short-term soil CO 2 flux and soil N transformations. Measurements were made on 6 and 7 May 1994 for three cropping systems (coastal bermudagrass ( Cynodon dactylon (L.) Pers.), continuously cultivated sorghum ( Sorghum bicolor (L.) Moench), and no-till sorghum) that had three different tillage practices (molbboard plow, chisel plow, and untilled as the control) imposed on a vertisol at the Blackland Research Center, Temple, Texas, USA. The soil CO 2 flux was calculated from the rate of CO 2 concentration increase inside each chamber. Soil inorganic N content (NO 2 N, NO 3 N, and NH 4 N) was measured from soil cores collected immediately preceding tillage and at 8, 24, and 102 h thereafter. The CO 2 flux over a 24 h period measured by both methods was greatest immediately after tillage, but maximum soil chamber fluxes were only about 10% of those measured by the canopy chamber. The large differences between chambers are a concern, and probably were related to the inability of the soil chamber to make a representative measurement for tilled surfaces and to the increased turbulence and possible associated pressure effects inside the canopy chamber. Increased soil surface area under the canopy chamber caused by increased soil surface roughness may also explain observed chamber differences. Fluxes were greatest in the bermudagrass and least in the continuously cultivated sorghum. Fluxes in the moldboard plow treatment were usually the greatest, and fluxes in the untiled treatment were considerably smaller than fluxes from either tilage treatment. For the first 24 h after tillage, there was no relationship between cumulative CO 2 flux and the change of inorganic N. Thus, to the extent that these inorganic N content changes reflect microbial activity, the short-term CO 2 flux from tilled soils is controlled more by mass flow processes related to a tillage-induced change in porosity than to immediate microbial activity.

Effects of prolonged hyperinsulinemia on serum leptin in normal human subjects.

Abstract: We have studied the effect of prolonged hyperinsulinemia and hyperglycemia on serum leptin levels in young non- obese males during 72-h euglycemic-hyperinsulinemic and hyperglycemic ( z 8.5 and 12.6 mM) clamps. Hyperinsuline- mia increased serum leptin concentrations (by RIA) dose- dependently. An increase in serum insulin concentration of . 200 pM for . 24 h was needed to significantly increase serum leptin. An increase of z 800 pM increased serum lep- tin by z 70% over 72 h. Changes in plasma glucose concen- trations (from z 5.0 to z 12.6 mM) or changes in plasma FFA concentrations (from , 100 to . 1,000 m M) had no ef- fect on serum leptin. Serum leptin concentrations changed with circadian rhythmicity. The cycle length was z 24 h, and the cycle amplitude (peak to trough) was z 50%. The circadian leptin cycles and the circadian cycles of total body insulin sensitivity (i.e., GIR, the glucose infusion rates needed to maintain euglycemia during hyperinsulinemic clamping) changed in a mirror image fashion. Moreover, GIR decreased between Days 2 and 3 (from 11.4 6 0.2 to 9.8 6 0.2 mg/kg min, P , 0.05) when mean 24-h leptin levels reached a peak. In summary, we found ( a ) that 72 h of hy- perinsulinemia increased serum leptin levels dose-depen- dently; ( b ) that hyperglycemia or high plasma FFA levels did not affect leptin release; ( c ) that leptin was released with circadian rhythmicity, and ( d ) that 24-h leptin cycles corre- lated inversely with 24-h cycles of insulin sensitivity. We speculate that the close positive correlation between body fat and leptin is mediated, at least in part, by insulin. ( J. Clin. Invest. 1997. 100:1107-1113.) Key words: hyperglyce- miafree fatty acidscircadian leptin releaseinsulin re- sistance

Language and Auditory-verbal Short-term Memory Impairments: Evidence for Common Underlying Processes

Abstract: We report an investigation of the short-term memory STM impairments of 15 aphasic subjects whose language profiles varied with respect to the relative involvement of lexical-semantic and phonological processes. On the hypothesis that STM is dependent on capacities intrinsic to language processing, repetition span should vary in conjunction with lexical-semantic and phonological impairment: Specifically, when lexical-semantic processing is impaired, phonological abilities provide primary support to span performance; when phonological processing is impaired, there should be increased reliance on lexical-semantic information. Support for this hypothesis was provided by correlating measures of semantic and phonological abilities with effects of imageability and frequency on repetition performance, and with serial position effects in retrieval of phonemes within a word and words within a string. The data are discussed within the framework of an interactive activation model of language processing.

Precision Determination of the Neutron Spin Structure Function g1n

Abstract: We report on a precision measurement of the neutron spin structure function ${g}_{1}^{n}$ using deep inelastic scattering of polarized electrons by polarized ${}^{3}\mathrm{He}$. For the kinematic range $0.014lxl0.7$ and $1l{Q}^{2}l17(\mathrm{GeV}/c{)}^{2}$, we obtain $\ensuremath{\int}{0.014}^{0.7}{g}_{1}^{n}(x)dx\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{-}0.036\ifmmode\pm\else\textpm\fi{}0.004(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.005(\mathrm{syst})$ at an average ${Q}^{2}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}5(\mathrm{GeV}/c{)}^{2}$. We find relatively large negative values for ${g}_{1}^{n}$ at low $x$. The results call into question the usual Regge theory method for extrapolating to $x\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0$ to find the full neutron integral $\ensuremath{\int}{1}^{}{g}_{1}^{n}(x)\mathrm{dx}$, needed for testing the quark-parton model and QCD sum rules.

The Coexistence of Multiple Distribution Systems for Financial Services: The Case of Property- Liability Insurance

Abstract: Property-liability insurance is distributed through a direct-writer system, where agents represent one insurer, and an independent-agency system, where agents represent several insurers. Independent-agency insurers have higher costs than direct writers. The market-imperfections hypothesis attributes the coexistence of the two types of insurers to impediments to competition, while the product-quality hypothesis holds that independent-agency insurers provide higher-quality services. The authors measure cost efficiency and profit efficiency for property-liability insurers and find strong support for the product-quality hypothesis, implying that independent-agency insurers produce higher-quality outputs and are compensated by higher revenues. Copyright 1997 by University of Chicago Press.

The fibrinolytic effects of intermittent pneumatic compression: mechanism of enhanced fibrinolysis.

Abstract: BACKGROUND AND OBJECTIVES: Intermittent pneumatic compression (IPC) is an effective form of deep vein thrombosis prophylaxis for general surgery patients. The antithrombotic effect of IPC is thought to be the result of increased venous velocity and stimulation of endogenous fibrinolysis. However, the mechanism of enhanced fibrinolytic activity and the relative effects on normal and postthrombotic veins have not been defined. The purposes of this study are 1) to quantify changes in fibrinolytic activity with IPC; 2) to study the mechanism of fibrinolytic enhancement with IPC; and 3) to evaluate whether postthrombotic patients have the same capacity for fibrinolytic enhancement with IPC as do normal subjects. METHODS: Twelve volunteers (6 normal and 6 postthrombotic) had 5 IPC devices applied for 120 minutes in random fashion, 1 per week x 5 weeks. The devices included single-chamber, sequential, foot, calf, and long-leg compression. Subjects had an indwelling antecubital venous cannula placed for blood drawn at baseline, 60, 120, and 180 minutes after IPC devices were applied. Global fibrinolytic activity (euglobulin fraction, fibrin plate assay), tissue plasminogen activator (tPA) antigen (Ag) and activity (Act), plasminogen activator inhibitor-1 (PAI-1) Ag and Act, alpha-2-antiplasmin-plasmin complexes, and von Willebrand factor (vWF) antigen were assayed. RESULTS: A striking elevation in fibrinolytic activity was noted at 180 minutes with all devices in normal subjects and postthrombotic patients (p = 0.01-0.0001); however, baseline and stimulated fibrinolytic activity was attenuated in postthrombotic patients (<0.03). The tPA-Act increased only in normal subjects (3.8 +/- 1.9%) (p = 0.057), despite a decrease in plasma tPA-Ag, which was observed in both normal subjects (-12.4 +/- 3.8%) (p = 0.009) and patients (-17.2 +/- 3.1%) (p = 0.001). PAI-1-Ag decreased in both normal subjects (-13.4 +/- 3.8%) (p = 0.007) and patients (-12.0 +/- 3.1%) (p = 0.013) with a marked reduction in PAI-1-Act in both normal subjects (p = 0.003) and patients (p = 0.004). There were no changes in vWF, and alpha-2-antiplasmin-plasmin complexes increased only in postthrombotic patients (p = 0.021). CONCLUSIONS: Stimulation of endogenous fibrinolytic activity occurs after IPC, both in normal subjects and postthrombotic patients; however, baseline and overall fibrinolytic response in postthrombotic patients is reduced. The mechanism of increased fibrinolytic activity is likely because of a reduction in PAI-1, with a resulting increase of tPA activity.

Evolution and Revolution in Child Psychiatry: ADHD as a Disorder of Adaptation

Abstract: Current knowledge about early plasticity and children's responsiveness to environmental modifications as well as the atheoretical nature of current nosological systems necessitate alternative models to explain the phenomena of childhood behavioral and emotional disturbances. Evolutionary biology provides one such framework. It organizes data from the behavioral and cognitive sciences and parallels similar efforts in other areas of medicine and biology. Through an evolutionary biological lens, some mental disorders are better viewed as an adaptive response to early pathogenic environments and/or reflect the optimization of brain function to some environments at the cost of poorer response to the demands of other environments. As an example, the authors examine attention-deficit/hyperactivity disorder (ADHD) in relation to evolutionary theories of psychology and biology and clarify the potentially adaptive nature of characteristics of inattention, impulsivity, and motoric hyperactivity, depending on the nature of child's environments. Reframing ADHD characteristics according to evolutionary theory has important treatment implications for clinicians and offers researchers opportunities for novel scientific discoveries.

An Employee Survey Measuring Total Quality Management Practices and Culture: Development and Validation

Abstract: This article presents a survey instrument designed to measure total quality management (TQM) and supporting organizational culture. In this study, 13 a priori dimensions of TQM and 10 a priori dime...