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Young's experiment is hailed as a milestone in ushering a new understanding of the wave nature of light and is even taught at the high school level. Unfortunately, even the most cursory presentation of the subject of diffraction becomes confusing. The theory and equations based on Fresnel's work appear arcane and incomprehensible to a high school student. In addition, students are "not" taught the significance of a phenomenon that has been observed since the time of Thomas Young: the bright band of light at the center of every single slit diffraction pattern. This paper presents a simple way to introduce the subject of diffraction based on Thomas Young's original work and explains how the interplay of different components of diffracted waves from a single slit creates the broad central maximum.

Background: The use of electronic vapor products (EVPs) increases the risks of nicotine addiction, drug-seeking behavior, mood disorders, and avoidable premature morbidities and mortality. We explored temporal trends in EVP use among US adolescents. Methods: We used data from the Youth Risk Behavior Survey for school grades 9 through 12 from 2015 (earliest available data) to 2021 (the most recently available data) from the US Centers for Disease Control and Prevention (n=57,006). Results: Daily use of EVPs increased from 2.0% in 2015 to 7.2% in 2019, a greater than 3.5-fold increase. Although the percentage decreased to 5.0% in 2021, it was still a >2.5-fold increase since 2015. In 2015, the percentage of EVP use was significantly higher in boys (2.8%) than girls (1.1%). By 2021, the percentage of EVP use was higher in girls (5.6%) than boys (4.5%), a 1.24-fold increase. In addition, the percentage of EVP use in 2021 was higher in White youth (6.5%) vs Black (3.1%), Asian (1.2%), and Hispanic/Latino (3.4%) youth compared to 2015, but White and Black adolescents had the highest increases of approximately 3.0-fold between 2015 and 2021. Adolescents in grade 12 had the highest percentages of EVP use at all periods. Conclusion: These data show alarming statistically significant and clinically important increases in EVP use in US adolescents in school grades 9 through 12. The magnitude of the increases may have been blunted by coronavirus disease 2019, a hypothesis that requires direct testing in analytic studies. These trends create clinical and public health challenges that require targeted interventions such as mass media campaigns and peer interventions to combat the influences of social norms that promote the adoption of risky health behaviors during adolescence. [ABSTRACT FROM AUTHOR]

Objectives (a) Update previous descriptions of trends in ASSB; (b) determine if factors previously associated with ASSB are replicated by updated data; and (c) generate new hypotheses about the occurrence of ASSB and racial inequalities in ASSB mortality. Methods National Center for Health Statistics files (International Classification of Diseases, Tenth Edition) Code W75 to describe race-ethnicity-specific ASSB occurrence. Results (a) ASSB mortality continues to increase significantly; for 1999-2016, 4.4-fold for NHB girls (45.8 per 100,000 in 2016), 3.5-fold for NHB boys (53.8), 2.7-fold for NHW girls (15.8) and 4.0-fold for NHW boys (25.9); (b) F actors previously associated with ASSB (unmarried mothers and mothers with low educational attainment, low infant birth weight, low gestational age, lack of prenatal care, male infant, multiple birth, high birth order) continue to be associated with both overall ASSB and inequalities adversely affecting NHB; (c) (1) geographic differences and similarities in ASSB occurrence support hypotheses related to positive deviance; (2) lower ASSB mortality for births attended by midwives as contrasted to physicians generate hypotheses related to both medical infrastructure and maternal engagement; (3) high rates of ASSB among infants born to teenage mothers generate hypotheses related to the possibility that poor maternal health may be a barrier to ASSB prevention based on education, culture and tradition. Conclusions for Practice These descriptive data may generate new hypotheses and targets for interventions for reducing both ASSB mortality and racial inequalities. Analytic epidemiologic studies designed a priori to do so are required to address these hypotheses., Author(s): Joanna Drowos [sup.1] , Aaron Fils [sup.2] , Maria C. Mejia de Grubb [sup.3] , Jason L. Salemi [sup.3] , Roger J. Zoorob [sup.3] , Charles H. Hennekens [sup.1] [...]

Background: Cigarette smoking remains the leading avoidable cause of premature death in the United States, accounting for approximately 500,000, or 1 in 5, deaths annually. We explored trends in cigarette smoking among US adolescents. Methods: We used data for adolescents in grades 9 through 12 from 1991 to 2021 from the Youth Risk Behavior Survey provided by the US Centers for Disease Control and Prevention. We explored trends overall as well as by sex, race/ethnicity, and school grade. Results: All cigarette use—assessed as ever, occasional, frequent, or daily—among adolescents declined markedly from 1991 to 2021. Specifically, ever use significantly decreased from 70.1% in 1991 to 17.8% in 2021 (P<0.05), an almost 4-fold decline. Occasional use significantly decreased from 27.5% in 1991 to 3.8% in 2021 (P<0.05), a greater than 7-fold decline. Frequent use significantly decreased from 12.7% to 0.7%, a greater than 18-fold decline. Daily use declined from 9.8% in 1991 to 0.6% in 2021, a greater than 16-fold decline. Cigarette smoking significantly decreased from 1999 to 2021 across sex, race/ethnicity, and school grade (P<0.05). In 2021, daily use was higher in boys vs girls; Hispanic/Latino and White youth vs Black and Asian youth; and 12th graders vs 9th, 10th, and 11th graders. Conclusion: These data show large and significant decreases in cigarette use among US adolescents in high school grades 9 through 12 from 1991 to 2021. Nonetheless, the data also suggest residual clinical and public health challenges that will require targeted interventions. [ABSTRACT FROM AUTHOR]

BackgroundAlthough cigarette smoking is the leading avoidable cause of premature death in middle age, some have claimed that no association is present among older persons.MethodsWe prospectively examined the relation of cigarette-smoking habits with mortality from all causes, cardiovascular causes, and cancer among 7178 persons 65 years of age or older without a history of myocardial infarction, stroke, or cancer who lived in one of three communities: East Boston, Massachusetts; Iowa and Washington counties, Iowa; and New Haven, Connecticut. At the time of the initial interview, prevalence rates of smoking in the three communities ranged from 5.2 to 17.8 percent among women and from 14.2 to 25.8 percent among men. During five years of follow-up there were 1442 deaths, 729 due to cardiovascular disease and 316 due to cancer.ResultsIn both sexes, rates of total mortality among current smokers were twice what they were among participants who had never smoked. Relative risks, as adjusted for age and community, were 2.1 among the men (95 percent confidence interval, 1.7 to 2.7) and 1.8 among the women (95 percent confidence interval, 1.4 to 2.4). Current smokers had higher rates of cardiovascular mortality than those who had never smoked (as adjusted for age and community, the relative risk was 2.0 [95 percent confidence interval, 1.4 to 2.9] among the men and 1.6 [95 percent confidence interval, 1.1 to 2.3] among the women), as well as increased rates of cancer mortality (relative risk, 2.4 [95 percent confidence interval, 1.4 to 4.1] among the men and 2.4 [95 percent confidence interval, 1.4 to 3.9] among the women). In both sexes, former smokers had rates of cardiovascular mortality similar to those of the participants who had never smoked, regardless of age at cessation, whereas the rates for all cancers, as well as smoking-related cancers, remained elevated among men who had once smoked.ConclusionsOur prospective findings indicate that the mortality hazards of smoking extend well into later life, and suggest that cessation will continue to improve life expectancy in older people.

Although smoking has been shown to be associated with excess morbidity and mortality, most studies have focused on young and middle-aged rather than elderly smokers. We examined the demographic characteristics and physical and psychological health of elderly cigarette smokers in four population-based studies (N = 3,673, 3,811, 2,811, and 4,165) of persons 65 years of age and older. Although there was substantial geographic variation in the percentages of smokers, the demographic and health characteristics of smokers were similar across the sites. Most women had never smoked, but most men were former or current smokers. The percentage of never smokers was highest in the "oldest old." Among the elderly ever smokers, men were more likely to have quit than women, and the relative percentage of former smokers increased with age. Current smokers were generally more likely to consume alcohol than never smokers. In this age group, cigarette smoking was typically associated with higher rates of physical disease and symptoms, poorer self-perceived health status, and higher levels of depressive symptoms. Based on these four large geographically diverse population surveys, cigarette smoking remains an important health burden and public health challenge among the elderly.