Problem: Minimizing driver fatigue among commercial motor-vehicle (CMV) drivers is a major safety issue in the United States. This study examines the effects of potentially fatigue-inducing factors ...inherent in truck driving work and company safety management in explaining: (a) drivers driving while fatigued, (b) the frequency of close calls due to fatigue, and (c) actual crashes among CMV drivers.
Method: Data for this study are derived from a survey of CMV drivers in 116 trucking firms, with all data being driver-reported. The relative roles of fatigue-inducing factors and safety management practices in explaining variation in fatigue, close calls, and crashes are reported, along with the roles of fatigue in affecting close calls and crashes via hierarchical regression.
Results: Findings indicated that fatigue-inducing factors inherent in driving work and safety practices accounted for appreciable variation in driving fatigued (R
2 = .42) and close calls (R
2 = .35), but not crash involvement. Driving while fatigued also accounted for incremental increases in the amount of variation in close calls, after consideration of inherent factors and safety practices.
Impact on industry: Findings indicate that safety practices (e.g., establishment of a strong safety culture, dispatcher scheduling practices, company assistance with fatiguing behaviors such as loading and unloading) have considerable potential to offset fatigue-inducing factors associated with truck driving work.
In high intensity focused ultrasound (HIFU) applications, tissue may be thermally necrosed by heating, emulsified by cavitation, or, as was recently discovered, emulsified using repetitive ...millisecond boiling caused by shock wave heating. Here, this last approach was further investigated. Experiments were performed in transparent gels and ex vivo bovine heart tissue using 1, 2, and 3 MHz focused transducers and different pulsing schemes in which the pressure, duty factor, and pulse duration were varied. A previously developed derating procedure to determine in situ shock amplitudes and the time-to-boil was refined. Treatments were monitored using B-mode ultrasound. Both inertial cavitation and boiling were observed during exposures, but emulsification occurred only when shocks and boiling were present. Emulsified lesions without thermal denaturation were produced with shock amplitudes sufficient to induce boiling in less than 20 ms, duty factors of less than 0.02, and pulse lengths shorter than 30 ms. Higher duty factors or longer pulses produced varying degrees of thermal denaturation combined with mechanical emulsification. Larger lesions were obtained using lower ultrasound frequencies. The results show that shock wave heating and millisecond boiling is an effective and reliable way to emulsify tissue while monitoring the treatment with ultrasound.
To report the distribution of Mini-Mental State Examination (MMSE) scores by age and educational level.
National Institute of Mental Health Epidemiologic Catchment Area Program surveys conducted ...between 1980 and 1984.
Community populations in New Haven, Conn; Baltimore, Md; St Louis, Mo; Durham, NC; and Los Angeles, Calif.
A total of 18,056 adult participants selected by probability sampling within census tracts and households.
Summary scores for the MMSE are given in the form of mean, median, and percentile distributions specific for age and educational level.
The MMSE scores were related to both age and educational level. There was an inverse relationship between MMSE scores and age, ranging from a median of 29 for those 18 to 24 years of age, to 25 for individuals 80 years of age and older. The median MMSE score was 29 for individuals with at least 9 years of schooling, 26 for those with 5 to 8 years of schooling, and 22 for those with 0 to 4 years of schooling.
Cognitive performance as measured by the MMSE varies within the population by age and education. The cause of this variation has yet to be determined. Mini-Mental State Examination scores should be used to identify current cognitive difficulties and not to make formal diagnoses. The results presented should prove to be useful to clinicians who wish to compare an individual patient's MMSE scores with a population reference group and to researchers making plans for new studies in which cognitive status is a variable of interest.
Depressive symptoms and metabolic control in African-Americans with type 2 diabetes.
T L Gary ,
R M Crum ,
L Cooper-Patrick ,
D Ford and
F L Brancati
Department of Epidemiology, The Johns Hopkins ...Medical Institutions, Baltimore, Maryland, USA.
Abstract
OBJECTIVE: To determine the prevalence of depressive symptoms and the relationship between depressive symptoms and metabolic
control. RESEARCH DESIGN AND METHODS: We conducted a cross-sectional study of 183 African-American adults aged 35-75 years
with type 2 diabetes who were recruited from two primary care clinics in East Baltimore, Maryland. Depressive symptoms, using
the Center for Epidemiological Studies Depression Scale (CES-D), HbA1c, fasting lipid profile, BMI, and blood pressure, were
measured on each participant. Diabetes-related health behaviors were assessed by questionnaire. RESULTS: The prevalence of
depressive symptoms (CES-D > or =22) was 30%. After adjustment for age, sex, income, social support, and duration of diabetes
in linear regression models, there were significant graded relationships between greater depressive symptoms and higher serum
levels of cholesterol and triglycerides (P<0.050). Similar, albeit less statistically significant, relationships were found
with higher levels of HbA1c (P = 0.104), diastolic blood pressure (P = 0.073), and LDL cholesterol (P = 0.176). Unexpectedly,
individuals who reported more depressive symptoms also had higher serum levels of HDL cholesterol (P = 0.047). The associations
were not explained by differences in diabetes-related health behaviors. CONCLUSIONS: Depressive symptoms are marginally associated
with suboptimal levels of HbA1c, diastolic blood pressure, and LDL cholesterol, and significantly associated with suboptimal
levels of total cholesterol and triglyceride levels. Prospective studies are required to determine whether improved identification
and management of depressive symptoms would enhance metabolic control in this population.
We hypothesized that neighborhood disadvantage might function as a determinant of ‘exposure opportunity’, an intermediate step on a path toward starting to use drugs illicitly. Testing this ...hypothesis, we analyzed self-report data gathered in 1992 by means of confidential interviews with 1416 urban-dwelling middle-school participants in a longitudinal field study. Within this epidemiologic sample, 50 youths said that someone actively had offered them a chance to take cocaine or smoke crack; tobacco had been offered to 395 youths; alcohol to 429 youths. Using multiple logistic regression to hold constant grade, sex, minority status, and peer drug use, we found a moderately potent association between neighborhood disadvantage and exposure to cocaine: youths living in the most disadvantaged neighborhoods (highest tertile) were an estimated 5.6 times more likely to have been offered cocaine, as compared to those in relatively advantaged neighborhoods (
P = 0.001). By comparison, there were weaker but statistically significant associations involving tobacco exposure opportunity (odds ratio, OR =1.7,
P = 0.004) and alcohol exposure opportunity (OR = 1.9,
P = 0.0005). Future research will clarify the etiologic significance of neighborhood disadvantage in pathways leading toward illicit drug use.
The importance of nonlinear acoustic wave propagation and ultrasound-induced cavitation in the acceleration of thermal lesion production by high intensity focused ultrasound was investigated ...experimentally and theoretically in a transparent protein-containing gel. A numerical model that accounted for nonlinear acoustic propagation was used to simulate experimental conditions. Various exposure regimes with equal total ultrasound energy but variable peak acoustic pressure were studied for single lesions and lesion stripes obtained by moving the transducer. Static overpressure was applied to suppress cavitation. Strong enhancement of lesion production was observed for high amplitude waves and was supported by modeling. Through overpressure experiments it was shown that both nonlinear propagation and cavitation mechanisms participate in accelerating lesion inception and growth. Using B-mode ultrasound, cavitation was observed at normal ambient pressure as weakly enhanced echogenicity in the focal region, but was not detected with overpressure. Formation of tadpole-shaped lesions, shifted toward the transducer, was always observed to be due to boiling. Boiling bubbles were visible in the gel and were evident as strongly echogenic regions in B-mode images. These experiments indicate that nonlinear propagation and cavitation accelerate heating, but no lesion displacement or distortion was observed in the absence of boiling.
In this work, the influence of nonlinear and diffraction effects on amplification factors of focused ultrasound systems is investigated. The limiting values of acoustic field parameters obtained by ...focusing of high power ultrasound are studied. The Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation was used for the numerical modeling. Solutions for the nonlinear acoustic field were obtained at output levels corresponding to both pre- and post-shock formation conditions in the focal area of the beam in a weakly dissipative medium. Numerical solutions were compared with experimental data as well as with known analytic predictions.
Subclinical findings on MRI of the brain are associated with poorer cognitive and neurological function among older adults. We sought to determine how alcohol consumption is related to these ...findings.
As part of the Cardiovascular Health Study, 3660 adults aged 65 years and older underwent MRI of the brain from 1992 to 1994. We excluded 284 participants with a confirmed history of cerebrovascular disease. We assessed self-reported intake of beer, wine, and liquor at the annual clinic visit closest to the date of the MRI and grouped participants into 6 categories: abstainers, former drinkers, <1 drink weekly, 1 to <7 drinks weekly, 7 to <15 drinks weekly, and >/=15 drinks weekly. Neuroradiologists assessed white matter grade, infarcts, ventricular size, and sulcal size in a standardized and blinded manner. We used multivariate regression to control for sociodemographic and clinical characteristics.
We found a U-shaped relationship between alcohol consumption and white matter abnormalities. Compared with abstainers, individuals consuming 1 to <7 drinks had an OR of 0.68, and those consuming >/=15 drinks weekly had an OR of 0.95 (p for quadratic term=0.01). Heavier alcohol consumption was associated with a lower prevalence of infarcts (OR for >/=15 drinks weekly relative to abstainers 0.59; P for trend=0.004), but larger ventricular size (OR for >/=15 drinks weekly relative to abstainers 1.32; P for trend=0.006) and sulcal size (OR for >/=15 drinks weekly relative to abstainers 1.53; P for trend=0.007).
Moderate alcohol consumption is associated with a lower prevalence of white matter abnormalities and infarcts, thought to be of vascular origin, but with a dose-dependent higher prevalence of brain atrophy on MRI among older adults. The extent to which these competing associations influence overall brain function will require further study.
Data from the Third National Health and Nutrition Examination Survey (1988–1994) were used to examine the relation between obesity and depression. Past-month depression was defined using criteria ...from the Diagnostic and Statistical Manual of Mental Disorders, Third Edition, and was measured with the Diagnostic Interview Schedule. Obesity was defined as a body mass index (weight (kg)/height (m)2) of 30 or higher. The authors compared risks of depression in obese and normal-weight (body mass index 18.5–24.9) persons. Obesity was associated with past-month depression in women (odds ratio (OR) = 1.82, 95% confidence interval (CI): 1.01, 3.3) but was not significantly associated in men (OR = 1.73, 95% CI: 0.56, 5.37). When obesity was stratified by severity, heterogeneity in the association with depression was observed. Class 3 (severe) obesity (body mass index ≥40) was associated with past-month depression in unadjusted analyses (OR = 4.98, 95% CI: 2.07, 11.99); the association remained strong after results were controlled for age, education, marital status, physician’s health rating, dieting for medical reasons, use of psychiatric medicines, cigarette smoking, and use of alcohol, marijuana, and cocaine. These findings suggest that obesity is associated with depression mainly among persons with severe obesity. Prospective studies will be necessary to clarify the obesity-depression relation but await the identification of potential risk factors for depression in the obese.
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