Enhancement of distribution system performance with reconfiguration, distributed generation and capacitor bank deployment.

This paper presents a comparative study of optimal reconfiguration, distributed generation, and shunt capacitor bank deployment for power loss minimization and voltage profile improvement in distribution systems. A metaheuristic approach based on the grey wolf optimizer (GWO) algorithm has been proposed for solving this high-dimensional, nonlinear, constrained, combinatorial optimization problem. Two standard IEEE 33- and 69-bus radial distribution systems (RDSs), and a practical 83-bus RDS of Taiwan Power Company have been considered for this study. The solutions obtained are compared with one another and those in the recent literature which includes classical and non-classical, metaheuristic-based methods. Going further, the little-studied problem of simultaneous reconfiguration, distributed generation, and capacitor bank deployment has been solved. The results suggest that the GWO has excellent potential for solving complicated optimization problems in distribution systems and elsewhere.

Combining data from primary and ancillary surveys to assess the association between neighborhood-level characteristics and health outcomes: the Multi-Ethnic Study of Artherosclerosis.

There is increasing interest in understanding the role of neighborhood-level factors on the health of individuals. Many large-scale epidemiological studies that accurately measure health status of individuals and individual risk factors exist. Sometimes these studies are linked to area-level databases (e.g. census) to assess the association between crude area-level characteristics and health. However, information from such databases may not measure the neighborhood-level constructs of interest. More recently, large-scale epidemiological studies have begun collecting data to measure specific features of neighborhoods using ancillary surveys. The ancillary surveys are composed of a separate, typically larger, set of individuals. The challenge is then to combine information from these two surveys to assess the role of neighborhood-level factors. We propose a method for combining information from the two data sources using a likelihood-based framework. We compare it with currently used ad hoc approaches via a simulation study. The simulation study shows that the proposed approach yields estimates with better sampling properties (less bias and better coverage probabilities) compared with the other approaches. However, there are cases where some ad hoc approaches may provide adequate estimates. We also compare the methods by applying them to the Multi-Ethnic Study of Atherosclerosis and its Neighborhood Ancillary Survey.

Self-efficacy as a predictor to PFMT adherence in a prevention of urinary incontinence clinical trial.

Past research suggests a positive correlation between self-efficacy (SE) and adherence to behavioral interventions. Less is known about SE and adherence in behavioral programs that are preventive in nature and specific to urinary incontinence (UI). Using treatment-group data from a previously reported randomized controlled trial, the authors assess the role of SE in predicting adherence to pelvic-floor muscle training (PFMT) for UI prevention in a sample of postmenopausal women. Results indicate that at 12 months follow-up, nearly 70% of participants reported medium or high adherence, performing the recommended PFMT regimen 2 to 3 times per week or more. Summary scores of both Task SE, beta = .25, SE (beta) = .08, p < .01, and Regulatory SE, beta = .43, SE (beta) = .06, p < .0001, predict adherence. Also, the authors found a modest decline in self-efficacy scores over time. These findings highlight the importance of SE in sustained behavioral change.

Adherence to a behavioral program to prevent incontinence.

This exploratory study assesses factors predicting adherence to a behavioral intervention to prevent urinary incontinence. Community-dwelling, post-menopausal women (N = 164) were taught pelvic floor muscle training (PFMT) and bladder training (BT) and followed with surveys for 1 year. Content analysis of open-ended responses coded descriptions of approaches participants used to incorporate PFMT into daily life. Exploratory bivariate and logistic regression analyses determined predictors of approach used and adherence. Results indicate women incorporated PFMT into their lives using either a routine or ad hoc approach. Those using a routine approach at 3 months were 12 times more likely to adhere (odds ratio [OR] = 12.4, confidence interval [CI] = 4.0-38.8, p < .001) at a high level at 3 months and significantly more likely to maintain that level 12 months post-intervention (OR = 2.7, CI = 1.2-6.0, p < .014). Practicing BT was related to high adherence.

Evaluation of a mass mailing recruitment strategy to obtain a community sample of women for a clinical trial of an incontinence prevention intervention.

OBJECTIVES: Questions exist about using mass mailings to recruit representative samples to participate in clinical trials. The MESA Prevention Study (Medical, Epidemiologic and Social Aspects of Aging), a randomized controlled clinical trial to prevent urinary incontinence (UI), utilized a mass mailing recruitment procedure to recruit a representative sample of women to participate in a behavioral modification program. This paper seeks to expand the literature of mass mailing recruitment strategies for prevention studies by describing the procedures used to recruit healthy, continent, post-menopausal women aged 55-80 years. METHODS: Sociodemographic data collected from recruited subjects is compared with on-line national census data to evaluate the representativeness of the sample recruited from a purchased mailing list. RESULTS: The mass mailing procedure resulted in 3.3% positive response. Of those that returned a positive response, 37.6% were deemed eligible at first screening. Comparisons of study demographic data with state and county census data indicate that the sample obtained was representative of the communities. CONCLUSIONS: The mass mailing strategy was an effective means of recruiting a representative sample of women, aged 55-80. Short falls and recommendations for successful community sample recruitment strategies for clinical trials in older adult women are elaborated upon.

Clinical depression and risk of out-of-hospital cardiac arrest.

BACKGROUND: The association of depression with coronary heart disease-related mortality has been widely recognized. This finding may partly reflect an association between depression and sudden death, in part because the imbalance between sympathetic and parasympathetic tone is altered in depressed subjects. We, thus, investigated whether the presence and severity of clinical depression was associated with a higher risk of sudden cardiac death. METHODS: We used data from a population-based case-control study of risk factors for incident out-of-hospital cardiac arrest (CA) conducted among enrollees of a health maintenance organization in western Washington State. Cases (n = 2228) were aged 40 to 79 years and experienced CA between January 1, 1980, and December 31, 1994. Controls (n = 4164) were a stratified random sample of enrollees defined by calendar year, age, sex, and prior heart disease. Clinical depression was defined as physician diagnosis of depression or use of antidepressant treatment within the year before the event. Referral to mental health clinics or hospitalization for depression defined severe depression. RESULTS: Clinically depressed patients had a higher odds ratio (OR) of CA (1.88; 95% confidence interval [CI], 1.59-2.23), which persisted after adjustment for confounders (OR, 1.43; 95% CI, 1.18-1.73). The association was observed in both sexes, in various age groups, and in subjects with prior physician-diagnosed heart disease (OR, 1.27; 95% CI, 1.01-1.60) and without prior physician-diagnosed heart disease (OR, 1.71; 95% CI, 1.22-2.41) (P = .13 for the interaction). Compared with nondepressed subjects, the risk of CA was increased in less severely depressed subjects (OR, 1.30; 95% CI, 1.04-1.63) and further increased in severely depressed subjects (OR, 1.77; 95% CI, 1.28-2.45) (P<.001 for trend). CONCLUSION: Clinical depression may be associated with a higher risk of CA independently of established coronary heart disease risk factors.

Learning outcomes of a group behavioral modification program to prevent urinary incontinence.

This study describes acquisition of knowledge and motor skill in bladder training (BT) and pelvic floor muscle training (PFMT) and adherence following a behavioral modification program (BMP). Essentially continent (0-5 episodes in past year) community-dwelling older women (n = 359) were randomized to treatment (n = 164), a 2-h group education session supplemented by one brief individualized session of approximately 10 min, or control (n = 195), no instruction, and followed for 12 months. Knowledge, motor skill, and adherence to the BMP were documented. Changes in pelvic muscle function and voiding interval were used to validate self-reported adherence. Following group instruction, mean BT and PFMT knowledge was 90 and 86%, respectively; 68% demonstrated correct PFMT technique without additional instruction, 29% required brief instruction, and 3% were unable to learn PFMT technique. Adherence ranged from 63 to 82% for PFMT and 58 to 67% for BT. Group instruction supplemented with brief individual instruction as needed is an effective teaching method for BT and PFMT.

Prevention of urinary incontinence by behavioral modification program: a randomized, controlled trial among older women in the community.

PURPOSE: We determined whether a behavioral modification program (BMP) taught to groups of continent older women would decrease the incidence of urinary incontinence, increase pelvic muscle strength and improve voiding control. MATERIALS AND METHODS: We performed a randomized, controlled trial comparing a BMP treatment group to a control, no treatment group in ambulatory, postmenopausal, continent women (0 to 5 days of incontinent episodes in the previous year) 55 years and older who were followed for 12 months. Qualified volunteers from 4 Michigan counties were randomly assigned to a control or a treatment group, consisting of a 2-hour classroom presentation on BMP followed 2 to 4 weeks later with individualized evaluation to test knowledge, adherence and skills in behavioral techniques, and brief reinforcement of the technique as needed. Followup was done by telephone and mail every 3 months except month 12, when all participants underwent final clinical evaluation. Outcome measures were continence status, pelvic floor muscle strength and voiding frequency/intervoid interval. RESULTS: A total of 195 control and 164 treated participants completed the study. Baseline data on the 2 groups were not statistically different. At 12 months the treatment group was statistically significantly better than the control group in continence status (p = 0.01), pelvic muscle strength (pressure score p = 0.0003 and displacement score p <0.0001), improved voiding frequency (p <0.0001) and intervoid interval (p <0.0001). CONCLUSIONS: To our knowledge we report the first randomized, controlled trial of BMP for preventing urinary incontinence in older women. It demonstrated feasibility and efficacy in improving continence status, pelvic muscle strength and voiding control as long as a year after treatment.

Sudden death and myocardial infarction in first degree relatives as predictors of primary cardiac arrest.

The hypothesis that family history (FH) of myocardial infarction (MI) and FH of sudden death (SD) are both independent risk factors for primary cardiac arrest (PCA) was examined in a case-control study. PCA cases were attended by paramedics (1988-1994) and community-based age and sex matched controls were identified. Subjects (25-74 years) were free of prior clinically-recognized heart disease and major co-morbidity. Interviewers obtained a detailed history of MI and SD in first-degree relatives from spouses of 235 cases and 374 control subjects. A parental history of early-onset SD (age <65) was associated with an increased risk of PCA (odds ratio (OR)=2.69, 95% CI=1.35-5.36), after adjustment for parental history of MI and other risk factors. A parental history of late-onset SD was not associated with PCA risk (OR=0.94, 95% CI=0.55-1.62). Additionally, parental history of SD was related to early-onset PCA (OR=1.89, 95% CI=1.08-3.30) but not to late-onset PCA (OR=0.89, 95% CI=0.49-1.61). In contrast, parental MI (early/late) was related to PCA (early/late), after adjustment for other risk factors and parental history of SD. Similar results were observed in first-degree relatives. Findings suggest a potential role of familial factors related to both MI and SD in PCA. Stronger findings for a familial patterning of PCA were noted for early onset disease in cases and their relatives.

Adolescent antecedents of high-risk driving behavior into young adulthood: substance use and parental influences.

Driver history data, in combination with previously collected tenth-grade questionnaire data, for 4403 subjects were analyzed by Poisson regression models to identify the significant substance use and parental characteristics predicting subsequent high-risk driving of new drivers (starting at age 16) through age 23-24 years. Substance use (cigarettes, marijuana, and alcohol) reported at age 15 was shown to be an important predictor of subsequent excess risk of serious offenses and serious crashes for both men and women. In addition, negative parental influences (lenient attitudes toward young people's drinking; low monitoring, nurturance, family connectedness), were also demonstrated to increase the risk of serious offenses and serious crashes for both men and women.

Income inequality, the psychosocial environment, and health: comparisons of wealthy nations.

BACKGROUND: The theory that income inequality and characteristics of the psychosocial environment (indexed by such things as social capital and sense of control over life's circumstances) are key determinants of health and could account for health differences between countries has become influential in health inequalities research and for population health policy. METHODS: We examined cross-sectional associations between income inequality and low birthweight, life expectancy, self-rated health, and age-specific and cause-specific mortality among countries providing data in wave III (around 1989-92) of the Luxembourg Income Study. We also used data from the 1990-91 wave of the World Values Survey (WVS). We obtained life expectancy, mortality, and low birthweight data from the WHO Statistical Information System. FINDINGS: Among the countries studied, higher income inequality was strongly associated with greater infant mortality (r=0.69, p=0.004 for women; r=0.74, p=0.002 for men). Associations between income inequality and mortality declined with age at death, and then reversed among those aged 65 years and older. Income inequality was inconsistently associated with specific causes of death and was not associated with coronary heart disease (CHD), breast or prostate cancer, cirrhosis, or diabetes mortality. Countries that had greater trade union membership and political representation by women had better child mortality profiles. Differences between countries in levels of social capital showed generally weak and somewhat inconsistent associations with cause-specific and age-specific mortality. INTERPRETATION: Income inequality and characteristics of the psychosocial environment like trust, control, and organisational membership do not seem to be key factors in understanding health differences between these wealthy countries. The associations that do exist are largely limited to child health outcomes and cirrhosis. Explanations for between-country differences in health will require an appreciation of the complex interactions of history, culture, politics, economics, and the status of women and ethnic minorities.

Low density lipoprotein particle size and risk of early-onset myocardial infarction in women.

Previous studies of middle-aged men have shown a univariate association between low density lipoprotein (LDL) particle diameter (size) and coronary heart disease, but this association has yet to be examined in younger women. Using a subsample from a population-based case-control study of women living in western Washington State, the authors examined the association between LDL particle size and risk of early-onset myocardial infarction (MI) in 1992-1995. Gradient gel electrophoresis was used to characterize LDL subclasses in nonfasting blood samples from 72 MI cases and 159 controls aged 20-44 years. Mean LDL particle size in cases was significantly smaller compared with controls (26.4 vs. 26.9 nm, p < 0.001), with an odds ratio of 2.3 (p < 0.0001) for a 1-nm smaller LDL particle size. These results were independent of age, menopausal status, smoking, diabetes, hypertension, and LDL cholesterol (odds ratios = 1.9-2.3 for a 1-nm smaller LDL particle size, all p < 0.02) but were not independent of body mass index, high density lipoprotein cholesterol, or triglyceride (odds ratios = 1.4, 1.4, and 1.1, respectively; all p > 0.05). Therefore, in age-adjusted analyses, smaller LDL particle size was associated with MI in young women, but the risk was attenuated after adjustments for metabolic factors related to both LDL particle size and MI.

Long-term follow-up of a high school alcohol misuse prevention program's effect on students' subsequent driving.

BACKGROUND: Alcohol-related injuries, particularly motor vehicle, are an important cause of adolescent mortality. School-based alcohol prevention programs have not been evaluated in terms of driving outcomes. This study examined the effects on subsequent driving of a high school-based alcohol prevention program. METHODS: The Alcohol Misuse Prevention Study included a randomized test of the effectiveness of an alcohol misuse prevention curriculum conducted among 4,635 10th-grade students. Students were assigned to intervention (n = 1,820) or control (n = 2,815) groups and were followed for an average of 7.6 years after licensure, which typically occurred during or shortly after 10th grade. Outcomes examined included alcohol-related and other serious offenses, and at-fault, single-vehicle, and alcohol-related crashes. RESULTS: Only serious offenses (which included alcohol-related) had a significant treatment effect (statistically marginal) after we adjusted for sex, age, race, alcohol use/misuse, family structure, presence of prelicense offenses, age of driver licensure, and parental attitudes toward teen drinking. The effect was found only during the first year of licensure (estimated adjusted relative risk = 0.80, confidence interval = 0.63-1.01). Two first-year serious offense interactions were found. The positive effect was strongest among the largest subgroup of students, those who were drinking less than one drink per week on average before the curriculum, compared with those who drank more than one drink per week (p = 0.009). The effect was also stronger for the small subgroup of students whose parents had not expressed disapproval of teens' drinking, compared with those whose parents had disapproved (p = 0.004). CONCLUSIONS: These findings suggest that a high school-based alcohol prevention program can positively affect subsequent driving, particularly that of students who do not use alcohol regularly. The results highlight the need to start prevention efforts early and extend them beyond the initial exposure to driving. Programs should incorporate the differing backgrounds of the students.

Changes in young adult offense and crash patterns over time.

A study of 13,809 young adult drivers in Michigan examined offenses and crashes ('incidents') for an average of 7 years after their original license date. During this period, 73% of subjects committed an offense that resulted in a conviction and 58% had a crash that was reported to the police. Forty-two percent had committed an offense classified as 'serious,' and 21% had an 'at-fault' crash. The odds of an offense being serious decreased approximately 8% per year of licensure, independent of gender or age at licensure. Similarly, the odds of a crash being at-fault decreased overall about 6% per year of licensure, but the decline was more than twice as fast for women as for men. Examining the empirical rates directly, it was found that the rate for minor offenses increased somewhat with time and then stabilized, while the rate for serious offenses declined. Also, offenses were less likely to be serious the later they occurred in the sequence of offenses for an individual. For crashes, the risk of having an at-fault crash declined more rapidly than the risk of a not-at-fault crash, although the rate of decrease began to equalize after approximately 5 years of licensure. The proportion of crashes that were at-fault did not decline over the sequence of crashes for an individual. Although crashes and offenses are positively correlated, they follow different trajectories over the early years of licensure.

RR interval variation, the QT interval index and risk of primary cardiac arrest among patients without clinically recognized heart disease.

AIMS: Autonomic tone influences RR interval variation (RRV) and the heart rate-corrected QT interval index (QTI). Together, QTI and RRV may improve characterization of sympathovagal control and estimation of risk of primary cardiac arrest. We therefore examined effects of QTI and short-term RRV from standard, 12-lead electrocardiograms on risk of primary cardiac arrest among persons without clinically recognized heart disease. METHODS AND RESULTS: We analysed data from a case-control study of risk factors for primary cardiac arrest among enrollees in a large health plan. Cases (n=505) were enrollees aged 18 to 79 years without history of heart disease who had primary cardiac arrest between 1980 and 1994. Controls (n=529) were a demographically similar, stratified random sample of enrollees. We determined enrollee characteristics from ambulatory medical records, QTI and RRV from standard, 12-lead electrocardiograms, and medication use from automated pharmacy files. Low and high values of QTI and RRV were designated as the first and fifth quintiles of QTI (96% and 107%) and RRV (35 ms and 120 ms) among controls. In a model adjusting for clinical predictors of primary cardiac arrest, RRV modified the association between QTI and risk of primary cardiac arrest (P=0.05). Compared to high RRV and low QTI, the risk of primary cardiac arrest (odds ratio [95% CI]) was 0.95 [0.73-1.23] at low RRV and QTI, 1.23 [0.97-1.57] at high RRV and QTI, and 1.55 [1.16-2.06] at low RRV and high QTI. Risk remained elevated after adjustment for other electrocardiographic predictors and medication use. CONCLUSION: Autonomic dysfunction, characterized by high QTI and low RRV on the standard, 12-lead electrocardiogram, is associated with an increased risk of primary cardiac arrest among persons without clinically recognized heart disease.

Race, clinical factors and pre-term birth in a low-income urban setting.

UNLABELLED: While infant mortality rates have declined for both White and African-American populations, the perennial two-fold excess in risk for African Americans remains unchanged, and indeed, may have increased since 1985. One potential explanation for the excess risk in African Americans might be racial differences in maternal clinical risk factors, such as prior pregnancy history and pregnancy complications. This paper examines the contributions of such clinical indicators to racial differences in pre-term delivery in a study sample of urban, low-income women, aged 18 to 43 years. METHODS: Study participants were enrolled during their first prenatal care visit at one of four hospital-based, prenatal care clinics in Baltimore City. Medical history and pregnancy outcome data were abstracted from clinical records. Multiple logistic regression models were used to assess the independent relationship between race and pre-term birth, after controlling for clinical factors. RESULTS: Without adjustment for clinical risk factors, African-American women were 1.8 times more likely than White women to have a pre-term birth outcome (95% confidence interval 1.20-2.78). After statistical adjustment for the clinical variables, however, the association between race and pre-term birth was diminished (OR = 1.64, 95% confidence interval: 0.99-2.72). Moreover, the associations between certain clinical risks and pre-term birth were stronger for African-American than White women. CONCLUSION: These results suggest that attention to clinical risk factors among African-American women may be an important avenue for reducing Black/White racial disparities in pre-term birth.

Influenza vaccination and the risk of primary cardiac arrest.

Influenza epidemics are associated with an excess of mortality not only from respiratory diseases but also from other causes, and cardiovascular mortality increases abruptly during influenza epidemics, with little evidence of a lag period. In a population-based case-control study, the authors examined whether influenza vaccination was associated with a reduced risk of out-of-hospital primary cardiac arrest (PCA), a major contributor to cardiovascular mortality in the community. Cases of PCA (n = 342) without prior heart disease or life-threatening comorbidity that occurred in King County, Washington, were identified from paramedic incident reports from October 1988 to July 1994. Demographically similar controls (n = 549) were identified from the community by using random digit dialing. Spouses of subjects were interviewed to assess treatment with influenza vaccine during the previous year and other risk factors. After adjustment for demographic, clinical, and behavioral risk factors, influenza vaccination was associated with a reduced risk of PCA (odds ratio = 0.51, 95 percent confidence interval: 0.33, 0.79). The authors suggest that while the association of influenza vaccination with a reduced risk of PCA is consistent with cohort studies of influenza vaccination and total mortality, further studies are needed to determine whether the observed association reflects protection or selection.

Dietary intake of long-chain n-3 polyunsaturated fatty acids and the risk of primary cardiac arrest.

Whether the dietary intake of long-chain n-3 polyunsaturated fatty acids (PUFAs) from seafood reduces the risk of ischemic heart disease remains a source of controversy, in part because studies have yielded inconsistent findings. Results from experimental studies in animals suggest that recent dietary intake of long-chain n-3 PUFAs, compared with saturated and monounsaturated fats, reduces vulnerability to ventricular fibrillation, a life-threatening cardiac arrhythmia that is a major cause of ischemic heart disease mortality. Until recently, whether a similar effect of long-chain n-3 PUFAs from seafood occurred in humans was unknown. We summarize the findings from a population-based case-control study that showed that the dietary intake of long-chain n-3 PUFAs from seafood, measured both directly with a questionnaire and indirectly with a biomarker, is associated with a reduced risk of primary cardiac arrest in humans. The findings also suggest that 1) compared with no seafood intake, modest dietary intake of long-chain n-3 PUFAs from seafood (equivalent to 1 fatty fish meal/wk) is associated with a reduction in the risk of primary cardiac arrest; 2) compared with modest intake, higher intakes of these fatty acids are not associated with a further reduction in such risk; and 3) the reduced risk of primary cardiac arrest may be mediated, at least in part, by the effect of dietary n-3 PUFA intake on cell membrane fatty acid composition. These findings also may help to explain the apparent inconsistencies in earlier studies of long-chain n-3 PUFA intake and ischemic heart disease.

Lipid-lowering medication and risk of injury.

Meta-analyses of early primary prevention trials of lipid-lowering therapies suggested increased risk of injury deaths among treated persons. Our population-based case-control study examined the association of lipid-lowering medication use with fatal and nonfatal injuries in 298 cases and 332 controls. No increased injury risk was observed among current (OR = 0.46, 95% CI 0.18-1.21) or past users (OR = .92, 95% CI 0.44-1.95), after adjustment for behavioral disorders, medical conditions, and health status. Stratified analyses did not reveal sub-groups at significantly increased risk. These results, consistent with recent clinical trials and meta-analyses, suggest no increased injury risk associated with lipid-lowering medications.

On summary measures analysis of the linear mixed effects model for repeated measures when data are not missing completely at random.

Subjects often drop out of longitudinal studies prematurely, yielding unbalanced data with unequal numbers of measures for each subject. A simple and convenient approach to analysis is to develop summary measures for each individual and then regress the summary measures on between-subject covariates. We examine properties of this approach in the context of the linear mixed effects model when the data are not missing completely at random, in the sense that drop-out depends on the values of the repeated measures after conditioning on fixed covariates. The approach is compared with likelihood-based approaches that model the vector of repeated measures for each individual. Methods are compared by simulation for the case where repeated measures over time are linear and can be summarized by a slope and intercept for each individual. Our simulations suggest that summary measures analysis based on the slopes alone is comparable to full maximum likelihood when the data are missing completely at random but is markedly inferior when the data are not missing completely at random. Analysis discarding the incomplete cases is even worse, with large biases and very poor confidence coverage.