Showing papers by "University of Rochester published in 2002"

Getting started with yeast.

Abstract: Publisher Summary The yeast Saccharomyces cerevisiae is now recognized as a model system representing a simple eukaryote whose genome can be easily manipulated. Yeast has only a slightly greater genetic complexity than bacteria and shares many of the technical advantages that permitted rapid progress in the molecular genetics of prokaryotes and their viruses. Some of the properties that make yeast particularly suitable for biological studies include rapid growth, dispersed cells, the ease of replica plating and mutant isolation, a well-defined genetic system, and most important, a highly versatile DNA transformation system. Being nonpathogenic, yeast can be handled with little precautions. Large quantities of normal baker's yeast are commercially available and can provide a cheap source for biochemical studies. The development of DNA transformation has made yeast particularly accessible to gene cloning and genetic engineering techniques. Structural genes corresponding to virtually any genetic trait can be identified by complementation from plasmid libraries. Plasmids can be introduced into yeast cells either as replicating molecules or by integration into the genome. In contrast to most other organisms, integrative recombination of transforming DNA in yeast proceeds exclusively via homologous recombination. Cloned yeast sequences, accompanied by foreign sequences on plasmids, can therefore be directed at will to specific locations in the genome.

The Use of Molecular Profiling to Predict Survival after Chemotherapy for Diffuse Large-B-Cell Lymphoma

Abstract: Background The survival of patients with diffuse large-B-cell lymphoma after chemotherapy is influenced by molecular features of the tumors. We used the gene-expression profiles of these lymphomas to develop a molecular predictor of survival. Methods Biopsy samples of diffuse large-B-cell lymphoma from 240 patients were examined for gene expression with the use of DNA microarrays and analyzed for genomic abnormalities. Subgroups with distinctive gene-expression profiles were defined on the basis of hierarchical clustering. A molecular predictor of risk was constructed with the use of genes with expression patterns that were associated with survival in a preliminary group of 160 patients and was then tested in a validation group of 80 patients. The accuracy of this predictor was compared with that of the international prognostic index. Results Three gene-expression subgroups — germinal-center B-cell–like, activated B-cell–like, and type 3 diffuse large-B-cell lymphoma — were identified. Two common oncogeni...

Overview of self-determination theory: An organismic-dialectical perspective.

Abstract: In the classical, Aristotelian, view of human development, people arc assumed to possess an active tendency toward psychological growth and integration. Endowed with an innate stT·h~ng to exercise and elaborate their interests, individuals tt:nd naturally to seck challenges, to discover new perspectives, and 10 actively internalize and transform cultural practices. By stretching thei.r capacities and expressing thei.r talents and propensities, people actualize their human potentials. Within this perspective, active growth is complemented by a tendency toward synthesis, organization, or relative unity of both knowledge and personality. Moreover, the integration of that which is experienced providt-s the basis for a coherent sense of selfa sense of wholeness, vitalit}\ and integrity. To the degree that individuals have attained a sense of self, they can act in accord "~th, or be "true" to, that seU: T his general view of an active, integrating organism with the potential to a.ct from a coherent sense of self can be found in psychodynamic and humanistic theories of personality and in cognitive theories of development. For example, psychoanalytic theorists posit inherent activity and a synthetic function of the ego (Freud, 1927; Nun berg, 1931; Meissner, 1981; White, 1963), and humani.~tic psyclJOlogists postulate an actualizing tendency (Angyal, 1963; Maslow, 1955; Rogers, 1963). Similarly, many cognitive d<:vclopmcntal theories emphasize an organizational or imcgrativc tendency as an endogenous feature of the organism, proposing that development is clmracterized by an overarching organization function through which new self-extensions are brought into coherence with other cognitive stmctures (Piagct, 1971; 'vVerncr, 1948).

Defining and Assessing Professional Competence

Abstract: ContextCurrent assessment formats for physicians and trainees reliably test core knowledge and basic skills. However, they may underemphasize some important domains of professional medical practice, including interpersonal skills, lifelong learning, professionalism, and integration of core knowledge into clinical practice.ObjectivesTo propose a definition of professional competence, to review current means for assessing it, and to suggest new approaches to assessment.Data SourcesWe searched the MEDLINE database from 1966 to 2001 and reference lists of relevant articles for English-language studies of reliability or validity of measures of competence of physicians, medical students, and residents.Study SelectionWe excluded articles of a purely descriptive nature, duplicate reports, reviews, and opinions and position statements, which yielded 195 relevant citations.Data ExtractionData were abstracted by 1 of us (R.M.E.). Quality criteria for inclusion were broad, given the heterogeneity of interventions, complexity of outcome measures, and paucity of randomized or longitudinal study designs.Data SynthesisWe generated an inclusive definition of competence: the habitual and judicious use of communication, knowledge, technical skills, clinical reasoning, emotions, values, and reflection in daily practice for the benefit of the individual and the community being served. Aside from protecting the public and limiting access to advanced training, assessments should foster habits of learning and self-reflection and drive institutional change. Subjective, multiple-choice, and standardized patient assessments, although reliable, underemphasize important domains of professional competence: integration of knowledge and skills, context of care, information management, teamwork, health systems, and patient-physician relationships. Few assessments observe trainees in real-life situations, incorporate the perspectives of peers and patients, or use measures that predict clinical outcomes.ConclusionsIn addition to assessments of basic skills, new formats that assess clinical reasoning, expert judgment, management of ambiguity, professionalism, time management, learning strategies, and teamwork promise a multidimensional assessment while maintaining adequate reliability and validity. Institutional support, reflection, and mentoring must accompany the development of assessment programs.

TRANSITION PATH SAMPLING: Throwing Ropes Over Rough Mountain Passes, in the Dark

Abstract: This article reviews the concepts and methods of transition path sampling. These methods allow computational studies of rare events without requiring prior knowledge of mechanisms, reaction coordinates, and transition states. Based upon a statistical mechanics of trajectory space, they provide a perspective with which time dependent phenomena, even for systems driven far from equilibrium, can be examined with the same types of importance sampling tools that in the past have been applied so successfully to static equilibrium properties.

Mediation of poly(ADP-ribose) polymerase-1-dependent cell death by apoptosis-inducing factor.

Abstract: Poly(ADP-ribose) polymerase-1 (PARP-1) protects the genome by functioning in the DNA damage surveillance network. PARP-1 is also a mediator of cell death after ischemia-reperfusion injury, glutamate excitotoxicity, and various inflammatory processes. We show that PARP-1 activation is required for translocation of apoptosis-inducing factor (AIF) from the mitochondria to the nucleus and that AIF is necessary for PARP-1–dependent cell death. N -methyl- N ′-nitro- N -nitrosoguanidine, H2O2, and N -methyl-d-aspartate induce AIF translocation and cell death, which is prevented by PARP inhibitors or genetic knockout of PARP-1, but is caspase independent. Microinjection of an antibody to AIF protects against PARP-1–dependent cytotoxicity. These data support a model in which PARP-1 activation signals AIF release from mitochondria, resulting in a caspase-independent pathway of programmed cell death.

Effect of Dialysis Dose and Membrane Flux in Maintenance Hemodialysis

Abstract: Background The effects of the dose of dialysis and the level of flux of the dialyzer membrane on mortality and morbidity among patients undergoing maintenance hemodialysis are uncertain. Methods We undertook a randomized clinical trial in 1846 patients undergoing thrice-weekly dialysis, using a two-by-two factorial design to assign patients randomly to a standard or high dose of dialysis and to a low-flux or high-flux dialyzer. Results In the standard-dose group, the mean (±SD) urea-reduction ratio was 66.3±2.5 percent, the single-pool Kt/V was 1.32±0.09, and the equilibrated Kt/V was 1.16±0.08; in the high-dose group, the values were 75.2±2.5 percent, 1.71±0.11, and 1.53±0.09, respectively. Flux, estimated on the basis of beta2-microglobulin clearance, was 3±7 ml per minute in the low-flux group and 34±11 ml per minute in the high-flux group. The primary outcome, death from any cause, was not significantly influenced by the dose or flux assignment: the relative risk of death in the high-dose group as com...

Revision of achievement goal theory: Necessary and illuminating.

Abstract: C. Midgley et al. (2001) raised important questions about the effects of performance-approach goals. The present authors disagree with their characterization of the research findings and implications for theory. They discuss 3 reasons to revise goal theory: (a) the importance of separating approach from avoidance strivings, (b) the positive potential of performance-approach goals, and (c) identification of the ways performance-approach goals can combine with mastery goals to promote optimal motivation. The authors review theory and research to substantiate their claim that goal theory is in need of revision, and they endorse a multiple goal perspective. The revision of goal theory is underway and offers a more complex, but necessary, perspective on important issues of motivation, learning, and achievement. In tins response. the authors dispel interpretation of their critical review of research on performance-approach goals as support for a dichotomous perspective of achievement goal theory. Second, the authors challenge the suggestion that accepting recent research findings and adopting a multiple goals perspective constitutes a theoretical revision of the assumption that mastery goals are always good and performance goals are always bad (J. M. Harackiewicz. K. E. Barron, P. R. Pintrich, P. R. Elliot, & T. M. Thrash. 2002, p. 643). The authors make a distinction between developments that contribute to the explanatory power of the theory and value-laden interpretations of theory and research. The authors argue that phrasing the latter in terms of the former is misleading and that it masks the necessity for a critical discussion over the desired purposes in different types of achievement contexts.

Approach-avoidance motivation in personality: approach and avoidance temperaments and goals.

Abstract: The present research examined the role of approach and avoidance motivation in models of personality. Specifically, it examined the hypothesis that approach and avoidance temperaments represent the foundation of several basic dimensions espoused in the trait adjective, affective disposition, and motivational system approaches to personality. Factor analytic support for the hypothesis was obtained in Studies 1, 2, and 6; measures of extraversion, positive emotionality, and behavioral activation system loaded together on 1 factor (Approach Temperament) and measures of neuroticism, negative emotionality, and behavioral inhibition system loaded on another factor (Avoidance Temperament). This 2-factor structure was shown to be independent of response biases. In Studies 3-7, approach and avoidance temperaments were shown to be systematically linked to achievement goals (both nomothetic and idiographic). The findings are discussed in terms of an integrative approach to personality.

Coherent emission of light by thermal sources

Abstract: A thermal light-emitting source, such as a black body or the incandescent filament of a light bulb, is often presented as a typical example of an incoherent source and is in marked contrast to a laser. Whereas a laser is highly monochromatic and very directional, a thermal source has a broad spectrum and is usually quasi-isotropic. However, as is the case with many systems, different behaviour can be expected on a microscopic scale. It has been shown recently that the field emitted by a thermal source made of a polar material is enhanced by more than four orders of magnitude and is partially coherent at a distance of the order of 10 to 100nm. Here we demonstrate that by introducing a periodic microstructure into such a polar material (SiC) a thermal infrared source can be fabricated that is coherent over large distances (many wavelengths) and radiates in well defined directions. Narrow angular emission lobes similar to antenna lobes are observed and the emission spectra of the source depends on the observation angle--the so-called Wolf effect. The origin of the coherent emission lies in the diffraction of surface-phonon polaritons by the grating.

Negotiation-based protocols for disseminating information in wireless sensor networks

Abstract: In this paper, we present a family of adaptive protocols, called SPIN (Sensor Protocols for Information via Negotiation), that efficiently disseminate information among sensors in an energy-constrained wireless sensor network. Nodes running a SPIN communication protocol name their data using high-level data descriptors, called meta-data. They use meta-data negotiations to eliminate the transmission of redundant data throughout the network. In addition, SPIN nodes can base their communication decisions both upon application-specific knowledge of the data and upon knowledge of the resources that are available to them. This allows the sensors to efficiently distribute data given a limited energy supply. We simulate and analyze the performance of four specific SPIN protocols: SPIN-PP and SPIN-EC, which are optimized for a point-to-point network, and SPIN-BC and SPIN-RL, which are optimized for a broadcast network. Comparing the SPIN protocols to other possible approaches, we find that the SPIN protocols can deliver 60% more data for a given amount of energy than conventional approaches in a point-to-point network and 80% more data for a given amount of energy in a broadcast network. We also find that, in terms of dissemination rate and energy usage, the SPIN protocols perform close to the theoretical optimum in both point-to-point and broadcast networks.

Reversible data hiding

Abstract: We present a novel reversible (lossless) data hiding (embedding) technique, which enables the exact recovery of the original host signal upon extraction of the embedded information. A generalization of the well-known LSB (least significant bit) modification is proposed as the data embedding method, which introduces additional operating points on the capacity-distortion curve. Lossless recovery of the original is achieved by compressing portions of the signal that are susceptible to embedding distortion, and transmitting these compressed descriptions as a part of the embedded payload. A prediction-based conditional entropy coder which utilizes static portions of the host as side-information improves the compression efficiency, and thus the lossless data embedding capacity.

Performance Matched Discretionary Accrual Measures

Abstract: Prior research shows that extant discretionary accrual models are misspecified when applied to firms with extreme performance. Nonetheless, use of such models in tests of earnings management and market efficiency is commonplace in the literature. We examine the specification and power of the test based on a performance-matched discretionary accrual measure and compare it with traditional discretionary accrual measures (e.g., Jones and Modified-Jones Models). Performance matching is on return on assets and industry and is designed to control for the effect of performance on measured discretionary accruals. The results suggest that our performance-matched discretionary accrual measure is a viable alternative to existing discretionary accrual models for use in earnings management research.

A taxonomy of wireless micro-sensor network models

Abstract: In future smart environments, wireless sensor networks will play a key role in sensing, collecting, and disseminating information about environmental phenomena. Sensing applications represent a new paradigm for network operation, one that has different goals from more traditional wireless networks. This paper examines this emerging field to classify wireless micro-sensor networks according to different communication functions, data delivery models, and network dynamics. This taxonomy will aid in defining appropriate communication infrastructures for different sensor network application sub-spaces, allowing network designers to choose the protocol architecture that best matches the goals of their application. In addition, this taxonomy will enable new sensor network models to be defined for use in further research in this area.

How Effective Are Interventions With Caregivers? An Updated Meta-Analysis

Abstract: Purpose: The purpose of this study was to determine the effectiveness of interventions for family caregivers of older adults. Design and Methods: Meta-analysis was used to synthesize the effects of 78 caregiver intervention studies for six outcome variables and six types of interventions. Results: The combined interventions produced a significant improvement of 0.14 to 0.41 standard deviation units, on average, for caregiver burden, depression, subjective well-being, perceived caregiver satisfaction, ability/knowledge, and care receiver symptoms. Intervention effects were larger for increasing caregivers’ ability/knowledge than for caregiver burden and depression. Psychoeducational and psychotherapeutic interventions showed the most consistent short-term effects on all outcome measures. Intervention effects for dementia caregivers were smaller than those for other groups. The number of sessions, the setting, care receiver age, caregiver age, gender, type of caregiver‐care receiver relationship (spouse vs adult child), initial burden, and study characteristics moderated the observed effects. Implications: Caregiver interventions are effective, but some interventions have primarily domain-specific effects rather than global effects. The differences between intervention types and moderators suggest ways of optimizing interventions.

Extrapulmonary translocation of ultrafine carbon particles following whole-body inhalation exposure of rats.

Abstract: Studies with intravenously injected ultrafine particles have shown that the liver is the major organ of their uptake from the blood circulation. Measuring translocation of inhaled ultrafine particles to extrapulmonary organs via the blood compartment is hampered by methodological difficulties (i.e., label may come off, partial solubilization) and analytical limitations (measurement of very small amounts). The objective of our pilot study was to determine whether ultrafine elemental carbon particles translocate to the liver and other extrapulmonary organs following inhalation as singlet particles by rats. We generated ultrafine (13)C particles as an aerosol with count median diameters (CMDs) of 20-29 nm (GSD 1.7) using electric spark discharge of (13)C graphite electrodes in argon. Nine Fischer 344 rats were exposed to these particles for 6 h. in whole-body inhalation chambers at concentrations of 180 and 80 microg/m(3); 3 animals each were killed at 0.5, 18, and 24 h postexposure. Six unexposed rats served as controls. Lung lobes, liver, heart, brain, olfactory bulb, and kidney were excised, homogenized, and freeze-dried for analysis of the added (13)C by isotope ratio mass spectrometry. Organic (13)C was not detected in the (13)C particles. The (13)C retained in the lung at 0.5 h postexposure was about 70% less than predicted by rat deposition models for ultrafine particles, and did not change significantly during the 24-h postexposure period. Normalized to exposure concentration, the added (13)C per gram of lung on average in the postexposure period was approximately 9 ng/g organ/microg/m(3). Significant amounts of (13)C had accumulated in the liver by 0.5 h postinhalation only at the high exposure concentration, whereas by 18 and 24 h postexposure the (13)C amount of the livers of all exposed rats was about fivefold greater than the (13)C burden retained in the lung. No significant increase in (13)C was detected in the other organs which were examined. These results demonstrate effective translocation of ultrafine elemental carbon particles to the liver by 1 d after inhalation exposure. Translocation pathways include direct input into the blood compartment from ultrafine carbon particles deposited throughout the respiratory tract. However, since predictive particle deposition models indicate that respiratory tract deposits alone may not fully account for the hepatic (13)C burden, input from ultrafine particles present in the GI tract needs to be considered as well. Such translocation to blood and extrapulmonary tissues may well be different between ultrafine carbon and other insoluble (metal) ultrafine particles.

Proterozoic ocean chemistry and evolution: A bioinorganic bridge?

Abstract: Recent data imply that for much of the Proterozoic Eon (2500 to 543 million years ago), Earth's oceans were moderately oxic at the surface and sulfidic at depth. Under these conditions, biologically important trace metals would have been scarce in most marine environments, potentially restricting the nitrogen cycle, affecting primary productivity, and limiting the ecological distribution of eukaryotic algae. Oceanic redox conditions and their bioinorganic consequences may thus help to explain observed patterns of Proterozoic evolution.

A developmental psychopathology perspective on adolescence.

Abstract: Developmental psychopathology offers an integrative framework for conceptualizing the course of development during adolescence, with particular relevance for understanding continuity and the emergence of psychopathology during this and subsequent developmental periods. In this article, the utility of a developmental psychopathology perspective for informing the design of research, prevention, and intervention is highlighted. Interdisciplinary, organizational models of development, emphasizing the dynamic relations between the developing individual and internal and external contexts, are discussed. Examination of boundaries between abnormal and normal development during adolescence offers important vantage points for articulating diversity in the developmental course during this period. Conceptualizing divergence and convergence in developmental pathways, continuity and discontinuity in development, and the transactions of risk and protective processes leading to maladaptation, psychopathology, and resilience are highlighted.

The three modern faces of mercury.

Abstract: The three modern "faces" of mercury are our perceptions of risk from the exposure of billions of people to methyl mercury in fish, mercury vapor from amalgam tooth fillings, and ethyl mercury in the form of thimerosal added as an antiseptic to widely used vaccines. In this article I review human exposure to and the toxicology of each of these three species of mercury. Mechanisms of action are discussed where possible. Key gaps in our current knowledge are identified from the points of view both of risk assessment and of mechanisms of action.

Falls and Fear of Falling: Which Comes First? A Longitudinal Prediction Model Suggests Strategies for Primary and Secondary Prevention

Abstract: OBJECTIVES: Previous cross-sectional studies have shown a correlation between falls and fear of falling, but it is unclear which comes first. Our objectives were to determine the temporal relationship between falls and fear of falling, and to see whether these two outcomes share predictors. DESIGN: A 20-month, population-based, prospective, observational study. SETTING: Salisbury, Maryland. Each evaluation consisted of a home-administered questionnaire, followed by a 4- to 5-hour clinic evaluation. PARTICIPANTS: The 2,212 participants in the Salisbury Eye Evaluation project who had baseline and 20-month follow-up clinic evaluations. At baseline, subjects were aged 65 to 84 and community dwelling and had a Mini-Mental State Examination score of 18 or higher. MEASUREMENTS: Demographics, visual function, comorbidities, neuropsychiatric status, medication use, and physical performance–based measures were assessed. Stepwise logistic regression analyses were performed to evaluate independent predictors of falls and fear of falling at the follow-up evaluation, first predicting incident outcomes and then predicting fall or fear-of-falling status at 20 months with baseline falling and fear of falling as predictors. RESULTS: Falls at baseline were an independent predictor of developing fear of falling 20 months later (odds ratio (OR) = 1.75; P < .0005), and fear of falling at baseline was a predictor of falling at 20 months (OR = 1.79; P < .0005). Women with a history of stroke were at risk of falls and fear of falling at follow-up. In addition, Parkinson's disease, comorbidity, and white race predicted falls, whereas General Health Questionnaire score, age, and taking four or more medications predicted fear of falling. CONCLUSION: Individuals who develop one of these outcomes are at risk for developing the other, with a resulting spiraling risk of falls, fear of falling, and functional decline. Because falls and fear of falling share predictors, individuals who are at a high risk of developing these endpoints can be identified.

Effects of coenzyme Q10 in early Parkinson disease: evidence of slowing of the functional decline.

Abstract: Background Parkinson disease (PD) is a degenerative neurological disorder for which no treatment has been shown to slow the progression. Objective To determine whether a range of dosages of coenzyme Q10is safe and well tolerated and could slow the functional decline in PD. Design Multicenter, randomized, parallel-group, placebo-controlled, double-blind, dosage-ranging trial. Setting Academic movement disorders clinics. Patients Eighty subjects with early PD who did not require treatment for their disability. Interventions Random assignment to placebo or coenzyme Q10at dosages of 300, 600, or 1200 mg/d. Main Outcome Measure The subjects underwent evaluation with the Unified Parkinson Disease Rating Scale (UPDRS) at the screening, baseline, and 1-, 4-, 8-, 12-, and 16-month visits. They were followed up for 16 months or until disability requiring treatment with levodopa had developed. The primary response variable was the change in the total score on the UPDRS from baseline to the last visit. Results The adjusted mean total UPDRS changes were +11.99 for the placebo group, +8.81 for the 300-mg/d group, +10.82 for the 600-mg/d group, and +6.69 for the 1200-mg/d group. ThePvalue for the primary analysis, a test for a linear trend between the dosage and the mean change in the total UPDRS score, was .09, which met our prespecified criteria for a positive trend for the trial. A prespecified, secondary analysis was the comparison of each treatment group with the placebo group, and the difference between the 1200-mg/d and placebo groups was significant (P= .04). Conclusions Coenzyme Q10was safe and well tolerated at dosages of up to 1200 mg/d. Less disability developed in subjects assigned to coenzyme Q10than in those assigned to placebo, and the benefit was greatest in subjects receiving the highest dosage. Coenzyme Q10appears to slow the progressive deterioration of function in PD, but these results need to be confirmed in a larger study.

Androgen Receptor (AR) Coregulators: An Overview

Abstract: The biological action of androgens is mediated through the androgen receptor (AR). Androgen-bound AR functions as a transcription factor to regulate genes involved in an array of physiological processes, most notably male sexual differentiation and maturation, and the maintenance of spermatogenesis. The transcriptional activity of AR is affected by coregulators that influence a number of functional properties of AR, including ligand selectivity and DNA binding capacity. As the promoter of target genes, coregulators participate in DNA modification, either directly through modification of histones or indirectly by the recruitment of chromatin-modifying complexes, as well as functioning in the recruitment of the basal transcriptional machinery. Aberrant coregulator activity due to mutation or altered expression levels may be a contributing factor in the progression of diseases related to AR activity, such as prostate cancer. AR demonstrates distinct differences in its interaction with coregulators from other steroid receptors due to differences in the functional interaction between AR domains, possibly resulting in alterations in the dynamic interactions between coregulator complexes.

Cross-modal plasticity: where and how?

Abstract: Animal studies have shown that sensory deprivation in one modality can have striking effects on the development of the remaining modalities. Although recent studies of deaf and blind humans have also provided convincing behavioural, electrophysiological and neuroimaging evidence of increased capabilities and altered organization of spared modalities, there is still much debate about the identity of the brain systems that are changed and the mechanisms that mediate these changes. Plastic changes across brain systems and related behaviours vary as a function of the timing and the nature of changes in experience. This specificity must be understood in the context of differences in the maturation rates and timing of the associated critical periods, differences in patterns of transiently existing connections, and differences in molecular factors across brain systems.

Disparities in Health Care by Race, Ethnicity, and Language Among the Insured:Findings From a National Sample

Abstract: BACKGROUND: Racial and ethnic disparities in health care have been well documented, but poorly explained. OBJECTIVE: To examine the effect of access barriers, including English fluency, on racial and ethnic disparities in health care. RESEARCH DESIGN: Cross-sectional analysis of the Community Tracking Survey (1996 –1997). SUBJECTS: Adults 18 to 64 years with private or Medicaid health insurance. MEASURES: Independent variables included race, ethnicity, and English fluency. Dependent variables included having had a physician or mental health visit, influenza vaccination, or mammogram during the past year. RESULTS: The health care use pattern for English-speaking Hispanic patients was not significantly different than for non-Hispanic white patients in the crude or multivariate models. In contrast, Spanish-speaking Hispanic patients were significantly less likely than non-Hispanic white patients to have had a physician visit (RR, 0.77; 95% CI, 0.72– 0.83), mental health visit (RR, 0.50; 95% CI, 0.32–0.76), or influenza vaccination (RR, 0.30; 95% CI, 0.15– 0.52). After adjustment for predisposing,need, and enabling factors, Spanish-speaking Hispanic patients showed significantly lower use than non-Hispanic white patients across all four measures. Black patients had a significantly lower crude relative risk of having received an influenza vaccination(RR, 0.73; 95% CI, 0.58–0.87). Adjustment for additional factors had little impact on this effect, but resulted in black patients being significantly less likely than non-Hispanic white patients to have had a visit with a mental health professional (RR, 0.46; 95% CI,0.37– 0.55). CONCLUSIONS: Among insured nonelderly adults, there are appreciable disparities in health-care use by race and Hispanic ethnicity. Ethnic disparities in care are largely explained by differences in English fluency, but racial disparities in care are not explained by commonly used access factors.

Predicting Success in College: A Longitudinal Study of Achievement Goals and Ability Measures as Predictors of Interest and Performance From Freshman Year Through Graduation

Abstract: The authors examined the role of achievement goals, ability, and high school performance in predicting academic success over students’ college careers. First, the authors examined which variables predicted students’ interest and performance in an introductory psychology course taken their first semester in college. Then, the authors followed students until they graduated to examine continued interest in psychology and performance in subsequent classes. Achievement goals, ability measures, and prior high school performance each contributed unique variance in predicting initial and long-term outcomes, but these predictors were linked to different educational outcomes. Mastery goals predicted continued interest, whereas performance-approach goals predicted performance. Ability measures and prior high school performance predicted academic performance but not interest. The findings support a multiple goals perspective.

Ambiguity, risk, and asset returns in continuous time

Abstract: Models of utility in stochastic continuous-time settings typically assume that beliefs are represented by a probability measure, hence ruling out a priori any concern with ambiguity. This paper formulates a continuous-time intertemporal version of multiple-priors utility, where aversion to ambiguity is admissible. In a representative agent asset market setting, the model delivers restrictions on excess returns that admit interpretations reflecting a premium for risk and a separate premium for ambiguity.