Showing papers by "Indiana University published in 2002"

Comparison of four chemotherapy regimens for advanced non-small-cell lung cancer.

Abstract: Background We conducted a randomized study to determine whether any of three chemotherapy regimens was superior to cisplatin and paclitaxel in patients with advanced non–small-cell lung cancer. Methods A total of 1207 patients with advanced non–small-cell lung cancer were randomly assigned to a reference regimen of cisplatin and paclitaxel or to one of three experimental regimens: cisplatin and gemcitabine, cisplatin and docetaxel, or carboplatin and paclitaxel. Results The response rate for all 1155 eligible patients was 19 percent, with a median survival of 7.9 months (95 percent confidence interval, 7.3 to 8.5), a 1-year survival rate of 33 percent (95 percent confidence interval, 30 to 36 percent), and a 2-year survival rate of 11 percent (95 percent confidence interval, 8 to 12 percent). The response rate and survival did not differ significantly between patients assigned to receive cisplatin and paclitaxel and those assigned to receive any of the three experimental regimens. Treatment with cisplatin...

Collaborative Care Management of Late-Life Depression in the Primary Care Setting: A Randomized Controlled Trial

Abstract: ContextFew depressed older adults receive effective treatment in primary care settings.ObjectiveTo determine the effectiveness of the Improving Mood–Promoting Access to Collaborative Treatment (IMPACT) collaborative care management program for late-life depression.DesignRandomized controlled trial with recruitment from July 1999 to August 2001.SettingEighteen primary care clinics from 8 health care organizations in 5 states.ParticipantsA total of 1801 patients aged 60 years or older with major depression (17%), dysthymic disorder (30%), or both (53%).InterventionPatients were randomly assigned to the IMPACT intervention (n = 906) or to usual care (n = 895). Intervention patients had access for up to 12 months to a depression care manager who was supervised by a psychiatrist and a primary care expert and who offered education, care management, and support of antidepressant management by the patient's primary care physician or a brief psychotherapy for depresssion, Problem Solving Treatment in Primary Care.Main Outcome MeasuresAssessments at baseline and at 3, 6, and 12 months for depression, depression treatments, satisfaction with care, functional impairment, and quality of life.ResultsAt 12 months, 45% of intervention patients had a 50% or greater reduction in depressive symptoms from baseline compared with 19% of usual care participants (odds ratio [OR], 3.45; 95% confidence interval [CI], 2.71-4.38; P<.001). Intervention patients also experienced greater rates of depression treatment (OR, 2.98; 95% CI, 2.34-3.79; P<.001), more satisfaction with depression care (OR, 3.38; 95% CI, 2.66-4.30; P<.001), lower depression severity (range, 0-4; between-group difference, −0.4; 95% CI, −0.46 to −0.33; P<.001), less functional impairment (range, 0-10; between-group difference, −0.91; 95% CI, −1.19 to −0.64; P<.001), and greater quality of life (range, 0-10; between-group difference, 0.56; 95% CI, 0.32-0.79; P<.001) than participants assigned to the usual care group.ConclusionThe IMPACT collaborative care model appears to be feasible and significantly more effective than usual care for depression in a wide range of primary care practices.

An Introduction to Logistic Regression Analysis and Reporting

Abstract: The purpose of this article is to provide researchers, editors, and readers with a set of guidelines for what to expect in an article using logistic regression techniques. Tables, figures, and charts that should be included to comprehensively assess the results and assumptions to be verified are discussed. This article demonstrates the preferred pattern for the application of logistic methods with an illustration of logistic regression applied to a data set in testing a research hypothesis. Recommendations are also offered for appropriate reporting formats of logistic regression results and the minimum observation-to-predictor ratio. The authors evaluated the use and interpretation of logistic regression presented in 8 articles published in The Journal of Educational Research between 1990 and 2000. They found that all 8 studies met or exceeded recommended criteria.

Late-Onset Sepsis in Very Low Birth Weight Neonates: The Experience of the NICHD Neonatal Research Network

Abstract: Objective. Late-onset sepsis (occurring after 3 days of age) is an important problem in very low birth weight (VLBW) infants. To determine the current incidence of late-onset sepsis, risk factors for disease, and the impact of late-onset sepsis on subsequent hospital course, we evaluated a cohort of 6956 VLBW (401–1500 g) neonates admitted to the clinical centers of the National Institute of Child Health and Human Development Neonatal Research Network over a 2-year period (1998–2000). Methods. The National Institute of Child Health and Human Development Neonatal Research Network maintains a prospective registry of all VLBW neonates admitted to participating centers within 14 days of birth. Expanded infection surveillance was added in 1998. Results. Of 6215 infants who survived beyond 3 days, 1313 (21%) had 1 or more episodes of blood culture-proven late-onset sepsis. The vast majority of infections (70%) were caused by Gram-positive organisms, with coagulase-negative staphylococci accounting for 48% of infections. Rate of infection was inversely related to birth weight and gestational age. Complications of prematurity associated with an increased rate of late-onset sepsis included patent ductus arteriosus, prolonged ventilation, prolonged intravascular access, bronchopulmonary dysplasia, and necrotizing enterocolitis. Infants who developed late-onset sepsis had a significantly prolonged hospital stay (mean length of stay: 79 vs 60 days). They were significantly more likely to die than those who were uninfected (18% vs 7%), especially if they were infected with Gram-negative organisms (36%) or fungi (32%). Conclusions. Late-onset sepsis remains an important risk factor for death among VLBW preterm infants and for prolonged hospital stay among VLBW survivors. Strategies to reduce late-onset sepsis and its medical, social, and economic toll need to be addressed urgently.

Effects of Cognitive training interventions with older adults. A randomized controlled trial

Abstract: ContextCognitive function in older adults is related to independent living and need for care. However, few studies have addressed whether improving cognitive functions might have short- or long-term effects on activities related to living independently.ObjectiveTo evaluate whether 3 cognitive training interventions improve mental abilities and daily functioning in older, independent-living adults.DesignRandomized, controlled, single-blind trial with recruitment conducted from March 1998 to October 1999 and 2-year follow-up through December 2001.Setting and ParticipantsVolunteer sample of 2832 persons aged 65 to 94 years recruited from senior housing, community centers, and hospital/clinics in 6 metropolitan areas in the United States.InterventionsParticipants were randomly assigned to 1 of 4 groups: 10-session group training for memory (verbal episodic memory; n = 711), or reasoning (ability to solve problems that follow a serial pattern; n = 705), or speed of processing (visual search and identification; n = 712); or a no-contact control group (n = 704). For the 3 treatment groups, 4-session booster training was offered to a 60% random sample 11 months later.Main Outcome MeasuresCognitive function and cognitively demanding everyday functioning.ResultsThirty participants were incorrectly randomized and were excluded from the analysis. Each intervention improved the targeted cognitive ability compared with baseline, durable to 2 years (P<.001 for all). Eighty-seven percent of speed-, 74% of reasoning-, and 26% of memory-trained participants demonstrated reliable cognitive improvement immediately after the intervention period. Booster training enhanced training gains in speed (P<.001) and reasoning (P<.001) interventions (speed booster, 92%; no booster, 68%; reasoning booster, 72%; no booster, 49%), which were maintained at 2-year follow-up (P<.001 for both). No training effects on everyday functioning were detected at 2 years.ConclusionsResults support the effectiveness and durability of the cognitive training interventions in improving targeted cognitive abilities. Training effects were of a magnitude equivalent to the amount of decline expected in elderly persons without dementia over 7- to 14-year intervals. Because of minimal functional decline across all groups, longer follow-up is likely required to observe training effects on everyday function.

Resilience Management in Social-ecological Systems: a Working Hypothesis for a Participatory Approach

Abstract: Approaches to natural resource management are often based on a presumed ability to predict probabilistic responses to management and external drivers such as climate. They also tend to assume that the manager is outside the system being managed. However, where the objectives include long-term sustainability, linked social-ecological systems (SESs) behave as complex adaptive systems, with the managers as integral components of the system. Moreover, uncertainties are large and it may be difficult to reduce them as fast as the system changes. Sustainability involves maintaining the functionality of a system when it is perturbed, or maintaining the elements needed to renew or reorganize if a large perturbation radically alters structure and function. The ability to do this is termed "resilience." This paper presents an evolving approach to analyzing resilience in SESs, as a basis for managing resilience. We propose a framework with four steps, involving close involvement of SES stakeholders. It begins with a stakeholder-led development of a conceptual model of the system, including its historical profile (how it got to be what it is) and preliminary assessments of the drivers of the supply of key ecosystem goods and services. Step 2 deals with identifying the range of unpredictable and uncontrollable drivers, stakeholder visions for the future, and contrasting possible future policies, weaving these three factors into a limited set of future scenarios. Step 3 uses the outputs from steps 1 and 2 to explore the SES for resilience in an iterative way. It generally includes the development of simple models of the system's dynamics for exploring attributes that affect resilience. Step 4 is a stakeholder evaluation of the process and outcomes in terms of policy and management implications. This approach to resilience analysis is illustrated using two stylized examples.

The Color of Discipline: Sources of Racial and Gender Disproportionality in School Punishment

Abstract: The disproportionate discipline of African-American students has been extensively documented; yet the reasons for those disparities are less well understood. Drawing upon one year of middle-school disciplinary data for an urban school district, we explored three of the most commonly offered hypotheses for disproportionate discipline based on gender, race, and socioeconomic status. Racial and gender disparities in office referrals, suspensions, and expulsions were somewhat more robust than socioeconomic differences. Both racial and gender differences remained when controlling for socioeconomic status. Finally, although evidence emerged that boys engage more frequently in a broad range of disruptive behavior, there were no similar findings for race. Rather, there appeared to be a differential pattern of treatment, originating at the classroom level, wherein African-American students are referred to the office for infractions that are more subjective in interpretation. Implications for teacher training and structural reform are explored.

Six-item screener to identify cognitive impairment among potential subjects for clinical research.

Abstract: Objective. To design a brief cognitive screener with acceptable sensitivity and specificity for identifying subjects with cognitive impairmentDesign. Cohort one is assembled from a community-based survey coupled with a second-stage diagnostic evaluation using formal diagnostic criteria for dementia.

GAL4 system in Drosophila: a fly geneticist's Swiss army knife.

Abstract: The last decade has seen an enormous expansion in the genetic toolbox of model organisms. This has been particularly apparent in the fruitfly, Drosophila melanogaster, in which the development of these tools and their ongoing extension, along with the completion of the genome sequence has allowed for the analysis of most any process. One particularly elegant example of tool development was the creation of the GAL4/UAS system for targeted gene expression in Drosophila. In addition to helping make Drosophila one of the most genetically tractable metazoans, this system has also helped Drosophila attract attention from the biotechnology industry as a viable means to investigate the function of genes implicated in a wide variety of medically and economically important processes. In this article, we review the GAL4/UAS system in Drosophila and the numerous extensions that have morphed it into a veritable Swiss army knife for the analysis of gene function.

Toward a Theory of Entrepreneurial Cognition: Rethinking the People Side of Entrepreneurship Research:

Abstract: The failure of past “entrepreneurial personality”—based research to clearly distinguish the unique contributions to the entrepreneurial process of entrepreneurs as people, has created a vacuum with...

Evolutionary origins and ecological consequences of endophyte symbiosis with grasses.

Abstract: Over the past 20 yr much has been learned about a unique symbiotic interaction between fungal endophytes and grasses. The fungi (Clavicipitaceae, Ascomycota) grow intercellularly and systemically in aboveground plant parts. Vertically transmitted asexual endophytes forming asymptomatic infections of cool‐season grasses have been repeatedly derived from sexual species that abort host inflorescences. The phylogenetic distribution of seed‐transmitted endophytes is strongly suggestive of cocladogenesis with their hosts. Molecular evidence indicates that many seed‐transmitted endophytes are interspecific hybrids. Superinfection may result in hyphal fusion and parasexual recombination. Most endophytes produce one or more alkaloid classes that likely play some role in defending the host plant against pests. Hybridization may have led to the proliferation of alkaloid‐production genes among asexual endophytes, favoring hybrids. The ergot alkaloid ergovaline, lolitrems, and lolines are produced by only a ...

The World Price of Insider Trading

Abstract: The existence and the enforcement of insider trading laws in stock markets is a phenomenon of the 1990s. A study of the 103 countries that have stock markets reveals that insider trading laws exist in 87 of them, but enforcement—as evidenced by prosecutions—has taken place in only 38 of them. Before 1990, the respective numbers were 34 and 9. We find that the cost of equity in a country, after controlling for a number of other variables, does not change after the introduction of insider trading laws, but decreases significantly after the first prosecution.

Technology and the Customer Interface: What Consumers Want in the Physical and Virtual Store:

Abstract: For companies to realize the benefits of recent innovations in customer interface technology, they need to understand the value consumers place on technology as part of the shopping process. A national survey of 2,120 online consumers was conducted to explore how people want to shop in both online and in-store environments and determine how interactive and conventional media work together to move consumers through the purchase process. The study investigated 128 different aspects of the shopping experience, from common elements to recent innovations. The results indicated that consumers are generally satisfied with the convenience, quality, selection, and value provided by retailers today. They are less satisfied with the level of service provided, the availability of product information, and the speed of the shopping process. The findings suggest that new technologies can enhance the shopping experience, but applications must be tailored to the unique requirements of consumer segments and product categories.

Listening in on bacteria: acyl-homoserine lactone signalling.

Abstract: Bacterial cell-to-cell signalling has emerged as a new area in microbiology. Individual bacterial cells communicate with each other and co-ordinate group activities. Although a lot of detail is known about the mechanisms of a few well-characterized bacterial communication systems, other systems have been discovered only recently. Bacterial intercellular communication has become a target for the development of new anti-virulence drugs.

Clinical significance of the cytochrome P450 2C19 genetic polymorphism.

Abstract: Cytochrome P450 2C19 (CYP2C19) is the main (or partial) cause for large differences in the pharmacokinetics of a number of clinically important drugs. On the basis of their ability to metabolise (S)-mephenytoin or other CYP2C19 substrates, individuals can be classified as extensive metabolisers (EMs) or poor metabolisers (PMs). Eight variant alleles (CYP2C19*2 to CYP2C19*8) that pre-diet PMs have been identified. The distribution of EM and PM genotypes and phenotypes shows wide interethnic differences. Nongenetic factors such as enzyme inhibition and induction, old age and liver cirrhosis can also modulate CYP2C19 activity. In EMs, ∼80% of doses of the proton pump inhibitors (PPIs) omeprazole, lansoprazole and pantoprazole seem to be cleared by CYP2C19, whereas CYP3A is more important in PMs. Five-fold higher exposure to these drugs is observed in PMs than in EMs of CYP2C19, and further increases occur during inhibition of CYP3A-catalysed alternative metabolic pathways in PMs. As a result, PMs of CYP2C19 experience more effective acid suppression and better healing of duodenal and gastric ulcers during treatment with omeprazole and lansoprazole compared with EMs. The pharmacoeconomic value of CYP2C19 genotyping remains unclear. Our calculations suggest that genotyping for CYP2C19 could save approximately $US5000 for every 100 Asians tested, but none for Caucasian patients. Nevertheless, genotyping for the common alleles of CYP2C19 before initiating PPIs for the treatment of reflux disease and H. pylori infection is a cost effective tool to determine appropriate duration of treatment and dosage regimens. Altered CYP2C19 activity does not seem to increase the risk for adverse drug reactions/interactions of PPIs. Phenytoin plasma concentrations and toxicity have been shown to increase in patients taking inhibitors of CYP2C19 or who have variant alleles and, because of its narrow therapeutic range, genotyping of CYP2C19 in addition to CYP2C9 may be needed to optimise the dosage of phenytoin. Increased risk of toxicity of tricyclic antidepressants is likely in patients whose CYP2C19 and/or CYP2D6 activities are diminished. CYP2C19 is a major enzyme in proguanil activation to cycloguanil, but there are no clinical data that suggest that PMs of CYP2C19 are at a greater risk for failure of malaria prophylaxis or treatment. Diazepam clearance is clearly diminished in PMs or when inhibitors of CYP2C19 are coprescribed, but the clinical consequences are generally minimal. Finally, many studies have attempted to identify relationships between CYP2C19 genotype and phenotype and susceptibility to xenobiotic-induced disease, but none of these are compelling.

The effects of monetary incentives on effort and task performance: theories, evidence, and a framework for research

Abstract: The purpose of this paper is to review theories and evidence regarding the effects of (performance-contingent) monetary incentives on individual effort and task performance. We provide a framework for understanding these effects in numerous contexts of interest to accounting researchers and focus particularly on how salient features of accounting settings may affect the incentives-effort and effort-performance relations. Our compilation and integration of theories and evidence across a wide variety of disciplines reveals significant implications for accounting research and practice. Based on the framework, theories, and prior evidence, we develop and discuss numerous directions for future research in accounting that could provide important insights into the efficacy of monetary reward systems.

Self-assembled nanoparticle probes for recognition and detection of biomolecules

Abstract: Colloidal gold nanocrystals have been used to develop a new class of nanobiosensors that is able to recognize and detect specific DNA sequences and single-base mutations in a homogeneous format At the core of this biosensor is a 25-nm gold nanoparticle that functions as both a nano-scaffold and a nano-quencher (efficient energy acceptor) Attached to this core are oligonucleotide molecules labeled with a thiol group at one end and a fluorophore at the other This hybrid bio/inorganic construct is found to spontaneously assemble into a constrained arch-like conformation on the particle surface Binding of target molecules results in a conformational change, which restores the fluorescence of the quenched fluorophore Unlike conventional molecular beacons with a stem-and-loop structure, the nanoparticle probes do not require a stem, and their background fluorescence increases little with temperature In comparison with the organic quencher Dabcyl (4,4'-dimethylaminophenyl azo benzoic acid), metal nanoparticles have unique structural and optical properties for new applications in biosensing and molecular engineering

Nonlinear Pricing Kernels, Kurtosis Preference, and Evidence from the Cross Section of Equity Returns

Abstract: This paper investigates nonlinear pricing kernels in which the risk factor is endogenously determined and preferences restrict the definition of the pricing kernel. These kernels potentially generate the empirical performance of nonlinear and multifactor models, while maintaining empirical power and avoiding ad hoc specifications of factors or functional form. Our test results indicate that preferencerestricted nonlinear pricing kernels are both admissible for the cross section of returns and are able to significantly improve upon linear single- and multifactor kernels. Further, the nonlinearities in the pricing kernel drive out the importance of the factors in the linear multi-factor model.

A 12-year prospective study of the long-term effects of early child physical maltreatment on psychological, behavioral, and academic problems in adolescence.

Abstract: Objective To determine whether child physical maltreatment early in life has long-term effects on psychological, behavioral, and academic problems independent of other characteristics associated with maltreatment. Design Prospective longitudinal study with data collected annually from 1987 through 1999. Setting and Participants Randomly selected, community-based samples of 585 children from the ongoing Child Development Project were recruited the summer before children entered kindergarten in 3 geographic sites. Seventy-nine percent continued to participate in grade 11. The initial in-home interviews revealed that 69 children (11.8%) had experienced physical maltreatment prior to kindergarten matriculation. Main Outcome Measures Adolescent assessment of school grades, standardized test scores, absences, suspensions, aggression, anxiety/depression, other psychological problems, drug use, trouble with police, pregnancy, running away, gang membership, and educational aspirations. Results Adolescents maltreated early in life were absent from school more than 1.5 as many days, were less likely to anticipate attending college compared with nonmaltreated adolescents, and had levels of aggression, anxiety/depression, dissociation, posttraumatic stress disorder symptoms, social problems, thought problems, and social withdrawal that were on average more than three quarters of an SD higher than those of their nonmaltreated counterparts. The findings held after controlling for family and child characteristics correlated with maltreatment. Conclusions Early physical maltreatment predicts adolescent psychological and behavioral problems, beyond the effects of other factors associated with maltreatment. Undetected early physical maltreatment in community populations represents a major problem worthy of prevention.

Standards for reporting the optical aberrations of eyes.

Abstract: In response to a perceived need in the vision community, an OSA taskforce was formed at the 1999 topical meeting on vision science and its applications (VSIA-99) and charged with developing consensus recommendations on definitions, conventions, and standards for reporting of optical aberrations of human eyes. Progress reports were presented at the 1999 OSA annual meeting and at VSIA-2000 by the chairs of three taskforce subcommittees on (1) reference axes, (2) describing functions, and (3) model eyes.

Do I really have to? User acceptance of mandated technology

Abstract: Extensive research supports the notion that usefulness and ease of use are primary drivers of user intentions to adopt new technology. However, this research has been conducted primarily in environ...

The gene mutated in autosomal recessive polycystic kidney disease encodes a large, receptor-like protein.

Abstract: Autosomal recessive polycystic kidney disease (ARPKD) is characterized by dilation of collecting ducts and by biliary dysgenesis and is an important cause of renal- and liver-related morbidity and mortality. Genetic analysis of a rat with recessive polycystic kidney disease revealed an orthologous relationship between the rat locus and the ARPKD region in humans; a candidate gene was identified. A mutation was characterized in the rat and screening the 66 coding exons of the human ortholog (PKHD1) in 14 probands with ARPKD revealed 6 truncating and 12 missense mutations; 8 of the affected individuals were compound heterozygotes. The PKHD1 transcript, approximately 16 kb long, is expressed in adult and fetal kidney, liver and pancreas and is predicted to encode a large novel protein, fibrocystin, with multiple copies of a domain shared with plexins and transcription factors. Fibrocystin may be a receptor protein that acts in collecting-duct and biliary differentiation.

Globalization and the great U-turn: Income inequality trends in 16 OECD countries

Abstract: The debate on the resurgence of income inequality in some advanced industrial societies has often focused on the impact of an increasingly integrated world economy, typified by growing capital mobility, heightened international competition, and an increase in migration. This study represents one of the first systematic, cross‐national examinations of the role of globalization in the inequality “U-turn.” Results indicate, on the one hand, that total inequality variation is principally affected by the percentage of the labor force in agriculture, followed by the institutional factors union density and decommodification, and only then by globalization. On the other hand, longitudinal variation in inequality, while still dominated by the percentage of the labor force in agriculture, is also principally affected by aspects of globalization, such as southern import penetration and direct investment outflow, and to a lesser extent by migration. In other words, globalization explains the longitudinal trend of inc...

Single-Molecule and Single-Nanoparticle SERS: Examining the Roles of Surface Active Sites and Chemical Enhancement

Abstract: Recent research in several groups has identified a new class of metal colloidal nanoparticles that is able to enhance the efficiencies of surface-enhanced Raman scattering (SERS) by as much as 1014−1015 fold. This enormous enhancement allows single-molecule detection and spectroscopy at room temperature. Previous single-molecule and single-particle studies have yielded important insights into the mechanism of electromagnetic field enhancement, but little is known about the contributions of surface active sites and chemical enhancement. Here we report a direct examination of chemical enhancement by using an integrated flow injection and ultrasensitive optical imaging/spectroscopy system. A key feature is that colloidal silver nanoparticles are immobilized on a glass surface inside a microflow device and that single-particle SERS signals are observed in real time while the immobilized particles are treated by chemical reagents in the flow cell. In situ surface plasmon scattering studies of spatially isolate...

Signals for Lorentz violation in electrodynamics

Abstract: An investigation is performed of the Lorentz-violating electrodynamics extracted from the renormalizable sector of the general Lorentz- and CPT-violating standard-model extension. Among the unconventional properties of radiation arising from Lorentz violation is birefringence of the vacuum. Limits on the dispersion of light produced by galactic and extragalactic objects provide bounds of $3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}16}$ on certain coefficients for Lorentz violation in the photon sector. The comparative spectral polarimetry of light from cosmologically distant sources yields stringent constraints of $2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}32}.$ All remaining coefficients in the photon sector are measurable in high-sensitivity tests involving cavity-stabilized oscillators. Experimental configurations in Earth- and space-based laboratories are considered that involve optical or microwave cavities and that could be implemented using existing technology.

The effect of sex, age and race on estimating percentage body fat from body mass index: The Heritage Family Study.

Abstract: Objective To study the effects of sex, age and race on the relation between body mass index (BMI) and measured percent body fat (%fat) Design Cross-sectional validation study of sedentary individuals Subjects The Heritage Family Study cohort of 665 black and white men and women who ranged in age from 17 to 65 y Measurements Body density determined from hydrostatic weighing Percentage body fat determined with gender and race-specific, two-compartment models BMI determined from height and weight, and sex and race in dummy coded form Results Polynomial regression showed that the relationship between %fat and BMI was quadratic for both men and women A natural log transformation of BMI adjusted for the non-linearity Test for homogeneity of log transformed BMI and gender showed that the male-female slopes were within random variance, but the intercepts differed For the same BMI, the %fat of females was 104% higher than that of males General linear models analysis of the women's data showed that age, race and race-by-BMI interaction were independently related to %fat The same analysis applied to the men's data showed that %fat was not just a function of BMI, but also age and age-by-BMI interaction Multiple regression analyses provided models that defined the bias Conclusions These data and results published in the literature show that BMI and %fat relationship are not independent of age and gender These data showed a race effect for women, but not men The failure to adjust for these sources of bias resulted in substantial differences in the proportion of subjects defined as obese by measured %fat

Statistical variation of aberration structure and image quality in a normal population of healthy eyes.

Abstract: A Shack-Hartmann aberrometer was used to measure the monochromatic aberration structure along the primary line of sight of 200 cyclopleged, normal, healthy eyes from 100 individuals. Sphero-cylindrical refractive errors were corrected with ophthalmic spectacle lenses based on the results of a subjective refraction performed immediately prior to experimentation. Zernike expansions of the experimental wave-front aberration functions were used to determine aberration coefficients for a series of pupil diameters. The residual Zernike coefficients for defocus were not zero but varied systematically with pupil diameter and with the Zernike coefficient for spherical aberration in a way that maximizes visual acuity. We infer from these results that subjective best focus occurs when the area of the central, aberration-free region of the pupil is maximized. We found that the population averages of Zernike coefficients were nearly zero for all of the higher-order modes except spherical aberration. This result indicates that a hypothetical average eye representing the central tendency of the population is nearly free of aberrations, suggesting the possible influence of an emmetropization process or evolutionary pressure. However, for any individual eye the aberration coefficients were rarely zero for any Zernike mode. To first approximation, wave-front error fell exponentially with Zernike order and increased linearly with pupil area. On average, the total wave-front variance produced by higher-order aberrations was less than the wave-front variance of residual defocus and astigmatism. For example, the average amount of higher-order aberrations present for a 7.5-mm pupil was equivalent to the wave-front error produced by less than 1/4 diopter (D) of defocus. The largest pupil for which an eye may be considered diffraction-limited was 1.22 mm on average. Correlation of aberrations from the left and right eyes indicated the presence of significant bilateral symmetry. No evidence was found of a universal anatomical feature responsible for third-order optical aberrations. Using the Marechal criterion, we conclude that correction of the 12 largest principal components, or 14 largest Zernike modes, would be required to achieve diffraction-limited performance on average for a 6-mm pupil. Different methods of computing population averages provided upper and lower limits to the mean optical transfer function and mean point-spread function for our population of eyes.

The SWAL-QOL and SWAL-CARE outcomes tool for oropharyngeal dysphagia in adults: III. Documentation of reliability and validity.

Abstract: Advances in the measurement of swallowing physiologic parameters have been clinician-driven, as has the development of intervention techniques to modify swallowing pathophysiology. However, a critical element to determining the success of such efforts will be established by the patients themselves. We conceptualized, developed, and validated the SWAL-QOL, a 93-item quality-of-life and quality-of-care outcomes tool for dysphagia researchers and clinicians. With 93 items, the SWAL-QOL was too long for practical and routine use in clinical research and practice. We used an array of psychometric techniques to reduce the 93-item instrument into two patient-centered outcomes tools: (1) the SWAL-QOL, a 44-item tool that assesses ten quality-of-life concepts, and (2) the SWAL-CARE, a 15-item tool that assesses quality of care and patient satisfaction. All scales exhibit excellent internal-consistency reliability and short-term reproducibility. The scales differentiate normal swallowers from patients with oropharyngeal dysphagia and are sensitive to differences in the severity of dysphagia as clinically defined. It is intended that the standardization and publication of the SWAL-QOL and the SWAL-CARE will facilitate their use in clinical research and clinical practice to better understand treatment effectiveness as a critical step toward improving patients' quality of life and quality of care.