Electronic Nicotine-Delivery Systems for Smoking Cessation.

BACKGROUND: Electronic nicotine-delivery systems - also called e-cigarettes - are used by some tobacco smokers to assist with quitting. Evidence regarding the efficacy and safety of these systems is needed. METHODS: In this open-label, controlled trial, we randomly assigned adults who were smoking at least five tobacco cigarettes per day and who wanted to set a quit date to an intervention group, which received free e-cigarettes and e-liquids, standard-of-care smoking-cessation counseling, and optional (not free) nicotine-replacement therapy, or to a control group, which received standard counseling and a voucher, which they could use for any purpose, including nicotine-replacement therapy. The primary outcome was biochemically validated, continuous abstinence from smoking at 6 months. Secondary outcomes included participant-reported abstinence from tobacco and from any nicotine (including smoking, e-cigarettes, and nicotine-replacement therapy) at 6 months, respiratory symptoms, and serious adverse events. RESULTS: A total of 1246 participants underwent randomization; 622 participants were assigned to the intervention group, and 624 to the control group. The percentage of participants with validated continuous abstinence from tobacco smoking was 28.9% in the intervention group and 16.3% in the control group (relative risk, 1.77; 95% confidence interval, 1.43 to 2.20). The percentage of participants who abstained from smoking in the 7 days before the 6-month visit was 59.6% in the intervention group and 38.5% in the control group, but the percentage who abstained from any nicotine use was 20.1% in the intervention group and 33.7% in the control group. Serious adverse events occurred in 25 participants (4.0%) in the intervention group and in 31 (5.0%) in the control group; adverse events occurred in 272 participants (43.7%) and 229 participants (36.7%), respectively. CONCLUSIONS: The addition of e-cigarettes to standard smoking-cessation counseling resulted in greater abstinence from tobacco use among smokers than smoking-cessation counseling alone. (Funded by the Swiss National Science Foundation and others; ESTxENDS ClinicalTrials.gov number, NCT03589989.).

Pollen exposure is associated with risk of respiratory symptoms during the first year of life.

BACKGROUND: Pollen exposure is associated with respiratory symptoms in children and adults. However, the association of pollen exposure with respiratory symptoms during infancy, a particularly vulnerable period, remains unclear. We examined whether pollen exposure is associated with respiratory symptoms in infants and whether maternal atopy, infant's sex or air pollution modifies this association. METHODS: We investigated 14,874 observations from 401 healthy infants of a prospective birth cohort. The association between pollen exposure and respiratory symptoms, assessed in weekly telephone interviews, was evaluated using generalized additive mixed models (GAMMs). Effect modification by maternal atopy, infant's sex, and air pollution (NO2 , PM2.5 ) was assessed with interaction terms. RESULTS: Per infant, 37 ± 2 (mean ± SD) respiratory symptom scores were assessed during the analysis period (January through September). Pollen exposure was associated with increased respiratory symptoms during the daytime (RR [95% CI] per 10% pollen/m3 : combined 1.006 [1.002, 1.009]; tree 1.005 [1.002, 1.008]; grass 1.009 [1.000, 1.23]) and nighttime (combined 1.003 [0.999, 1.007]; tree 1.003 [0.999, 1.007]; grass 1.014 [1.004, 1.024]). While there was no effect modification by maternal atopy and infant's sex, a complex crossover interaction between combined pollen and PM2.5 was found (p-value 0.003). CONCLUSION: Even as early as during the first year of life, pollen exposure was associated with an increased risk of respiratory symptoms, independent of maternal atopy and infant's sex. Because infancy is a particularly vulnerable period for lung development, the identified adverse effect of pollen exposure may be relevant for the evolvement of chronic childhood asthma.

In situx-ray analysis of misfit strain and curvature of bent polytypic GaAs-InxGa1-xAs core-shell nanowires.

Misfit strain in core-shell nanowires can be elastically released by nanowire bending in case of asymmetric shell growth around the nanowire core. In this work, we investigate the bending of GaAs nanowires during the asymmetric overgrowth by an InxGa1-xAs shell caused by avoiding substrate rotation. We observe that the nanowire bending direction depends on the nature of the substrate's oxide layer, demonstrated by Si substrates covered by native and thermal oxide layers. Further, we follow the bending evolution by time-resolvedin situx-ray diffraction measurements during the deposition of the asymmetric shell. The XRD measurements give insight into the temporal development of the strain as well as the bending evolution in the core-shell nanowire.

Impact of the Shadowing Effect on the Crystal Structure of Patterned Self-Catalyzed GaAs Nanowires.

The growth of regular arrays of uniform III-V semiconductor nanowires is a crucial step on the route toward their application-relevant large-scale integration onto the Si platform. To this end, not only does optimal vertical yield, length, and diameter uniformity have to be engineered, but also, control over the nanowire crystal structure has to be achieved. Depending on the particular application, nanowire arrays with varying area density are required for optimal device efficiency. However, the nanowire area density substantially influences the nanowire growth and presents an additional challenge for nanowire device engineering. We report on the simultaneous in situ X-ray investigation of regular GaAs nanowire arrays with different area density during self-catalyzed vapor-liquid-solid growth on Si by molecular-beam epitaxy. Our results give novel insight into selective-area growth and demonstrate that shadowing of the Ga flux, occurring in dense nanowire arrays, has a crucial impact on the evolution of nanowire crystal structure. We observe that the onset of Ga flux shadowing, dependent on array pitch and nanowire length, is accompanied by an increase of the wurtzite formation rate. Our results moreover reveal the paramount role of the secondary reflected Ga flux for VLS NW growth (specifically, that flux that is reflected directly into the liquid Ga droplet).

Radial Growth of Self-Catalyzed GaAs Nanowires and the Evolution of the Liquid Ga-Droplet Studied by Time-Resolved in Situ X-ray Diffraction.

We report on a growth study of self-catalyzed GaAs nanowires based on time-resolved in situ X-ray structure characterization during molecular-beam-epitaxy in combination with ex situ scanning-electron-microscopy. We reveal the evolution of nanowire radius and polytypism and distinguish radial growth processes responsible for tapering and side-wall growth. We interpret our results using a model for diameter self-stabilization processes during growth of self-catalyzed GaAs nanowires including the shape of the liquid Ga-droplet and its evolution during growth.

Participation in medical activities beyond standard consultations by Swiss general practitioners: a cross-sectional study.

BACKGROUND: Few data exist to support the observation that general practitioners (GPs) occupy many important positions in our communities or to characterize which GPs devote more of their time to such activities. We sought to characterize community-based complementary medical activities performed by GPs in the canton Vaud, Switzerland. METHODS: All GPs in a region were invited to participate in a cross-sectional study (n = 600) examining engagement in complementary activities beyond standard ambulatory consultations. Categories included teaching, care giving in specific structures, roles as medical experts or company doctors, community care giving, and others completed by the GP. GPs were asked the number of hours devoted monthly to each activity and whether or not they are remunerated for this work. RESULTS: One hundred and sixty-eight GPs responded (28%), with 149 (92%) reporting that they were engaged in at least one activity beyond their in-office consultations, including 117 (72%) in community care-giving (ex: care for addictions or refugees). Altogether, GPs spend on average 5.8 h a week on these activities. One-hundred and twenty-three GPs (82%) were remunerated for at least one of their complementary engagements. Predictors of participation in a larger number of complementary activities were working in a rural area (IRR 1.29, 95% CI 1.05 to 1.57) and having a higher weekly workload (IRR 1.01 for each additional hour, 95% CI 1.01 to 1.02). CONCLUSION: The vast majority of GPs engage in activities beyond their standard clinic tasks and they are typically reimbursed. GPs in rural areas and those who work more hours per week are more likely to engage in complementary activities.

[Design and user-testing of a decision aid comparing medications for smoking cessation]. / Outil d'aide à la décision comparant les traitements pharmacologiques pour l'arrêt du tabac.

Medications for smoking cessation, such as nicotine replacement, bupropion and varenicline have comparable efficacy, but present different advantages and drawbacks, making patient-specific preferences important when choosing a medication for smoking cessation. Through 3 PDCA cycles (Plan-Do-Check-Act), we developed and user-tested a decision aid for use during consultations. It contains the most relevant information for choosing a smoking cessation medication and is freely available online. The methodology used for its development could be employed for other decision aids for preference-sensitive decisions.

Les médicaments d'aide au sevrage tabagique tels que les substituts nicotiniques, le bupropion et la varénicline présentent une efficacité comparable mais des avantages et inconvénients différents dus à leur mécanisme d'action. Pour augmenter l'adhérence au traitement et les chances de réussite d'un sevrage tabagique, il est important de définir les préférences de traitement du patient. Pour soutenir cette démarche, au cours de 3 cycles PDCA (Plan-Do-Check-Act), nous avons développé et testé un outil d'aide à la décision qui contient les informations jugées les plus pertinentes quant au choix du médicament pour arrêter de fumer. L'outil est disponible gratuitement sur internet. La méthodologie utilisée ici pourrait être appliquée pour le développement d'autres outils d'aide à la décision.

Use of tobacco, nicotine and cannabis products among students in Switzerland.

Introduction: Most people who smoke cigarettes begin in their teens and teens may also be attracted to new tobacco, nicotine, and cannabis products. We describe use prevalence among upper-secondary school students in Switzerland, including daily use, of tobacco, nicotine, and cannabis products. Methods: We invited secondary school students (age 15 to 21) in two Swiss cantons to take an online survey between October 2021 and February 2022. The survey collected demographic information and asked how frequently they used tobacco products (cigarettes in commercial packages, self-rolled cigarettes, hookahs, pipes, cigars and cigarillos, tobacco heating systems, snus, snuff), non-tobacco nicotine products (nicotine pouches, e-cigarettes with and without nicotine), and cannabis products (smoking with and without tobacco, cannabis vaping). Answers were scored on a Likert scale (no use in past month, less than weekly, weekly but not daily, daily use, prefer not to say), then tabulated and reported as descriptive statistics. Results: Of 32,614 students in the schools we contacted, 9,515 (29.2%) completed the survey; 49.5% identified as female and 48.4% as male; 9.5% were under 16, 47% were 16-17, 27.5% were 18-19, and 16% were over 19. Reported daily use was most frequent for tobacco cigarettes in commercial packages (14.2%), snus (4.1%) and cannabis smoking with tobacco (3.6%). Most participants (54.8%) reported they had used at least one product at least once within the last month. Conclusion: Students who used a product were most likely to smoke cigarettes, but many regularly used new tobacco, nicotine and cannabis products, though use frequency varies.

Sex Differences in the Association Between Cumulative Use of Cannabis and Cognitive Function in Middle Age: The Coronary Artery Risk Development in Young Adults Study.

Background: Cannabis use may impair cognitive function (CF) differently in men and women, due to sex-specific differences in neurobiological mechanisms and environmental risk factors. Objective: Assess sex differences in the association between cumulative exposure to cannabis and cognitive performance in middle age. Methods: We studied participants from the Coronary Artery Risk Development in Young Adults (CARDIA) Study, including Black and White men and women 18-30 years old at baseline followed over 30 years. Our cross-sectional analysis of CF scores at year 30 was stratified by sex. We computed categories of cumulative exposure in "cannabis-years" (1 cannabis-year=365 days of use) from self-reported use every 2 to 5 years over 30 years. At years 25 and 30, we assessed CF with the Rey Auditory Verbal Learning Test (verbal memory), the Digit Symbol Substitution Test (processing speed), and the Stroop Interference Test (executive function). At year 30, additional measures included Category and Letter Fluency Test (verbal ability) and the Montreal Cognitive Assessment (global cognition). We computed standardized scores for each cognitive test and applied multivariable adjusted linear regression models for self-reported cumulative cannabis use, excluding participants who used cannabis within 24 h. In a secondary analysis, we examined the association between changes in current cannabis use and changes in CF between years 25 and 30. Results: By year 30, 1,352 men and 1,793 women had measures of CF; 87% (N=1,171) men and 84% (N=1,502) women reported ever cannabis use. Men had a mean cumulative use of 2.57 cannabis-years and women 1.29 cannabis-years. Self-reported cumulative cannabis use was associated with worse verbal memory in men (e.g., -0.49 standardized units [SU] for ≥5 cannabis-years of exposure; 95% CI=-0.76 to -0.23), but not in women (SU=0.02; 95% CI=-0.26 to 0.29). Other measures of CF were not associated with cannabis. Changes in current cannabis use between years 25 and 30 were not associated with CF in men or women. Conclusions: Self-reported cumulative cannabis exposure was associated with worse verbal memory in men but not in women. Researchers should consider stratified analyses by sex when testing the association between cannabis and cognition.

Exploiting flux shadowing for strain and bending engineering in core-shell nanowires.

Here we report on the non-uniform shell growth of InxGa1-xAs on the GaAs nanowire (NW) core by molecular beam epitaxy (MBE). The growth was realized on pre-patterned silicon substrates with the pitch size (p) ranging from 0.1 µm to 10 µm. Considering the preferable bending direction with respect to the MBE cells as well as the layout of the substrate pattern, we were able to modify the strain distribution along the NW growth axis and the subsequent bending profile. For NW arrays with a high number density, the obtained bending profile of the NWs is composed of straight (barely-strained) and bent (strained) segments with different lengths which depend on the pitch size. A precise control of the bent and straight NW segment length provides a method to design NW based devices with length selective strain distribution.

The Coronary Artery Risk Development in Young Adults (CARDIA) Study.

BACKGROUND: Resting heart rate can predict cardiovascular disease. Heart rate increases with tobacco smoking, but its association with cannabis use is unclear. We studied the association between current and cumulative cannabis use and heart rate. METHODS: We used data from the Coronary Artery Risk Development in Young Adults (CARDIA) Study, a large prospective cohort of 5115 Black and white women and men followed over 30 years. We explored the association between cannabis exposure and heart rate, adjusted for demographic factors, cardiovascular risk factors, alcohol and other illicit drug use, physical activity, and beta-blockers, in mixed longitudinal models censoring participants with cardiovascular disease. RESULTS: CARDIA participants contributed to 35,654 individual examinations over 30 years. At the Year 30 examination, 471 out of 3269 (14%) currently used cannabis. In multivariable adjusted models, compared to no current use, using cannabis 5 times per month was associated with lower heart rate of -0.7 beats per minute (95% confidence interval: -1.0 to -0.3), and daily use with lower heart rate of -2.1 beats per minute (95% confidence interval: -3.0 to -1.3, overall P < .001). Cumulative exposure to cannabis use was not associated with heart rate. CONCLUSION: Recent current cannabis use was associated with lower resting heart rate. The findings appeared to be transient because past cumulative exposure to cannabis was not associated with heart rate. This adds to the growing body of evidence suggesting a lack of deleterious association of cannabis use at a level typical of the general population on surrogate outcomes of cardiovascular disease.

The price of nicotine dependence: A comparison of the cost of nicotine across products in Switzerland, Germany, USA, Sweden, France and the UK, in 2019.

INTRODUCTION: Tobacco cigarette taxes aim at reducing smoking, but smokers are still dependent on nicotine and need safe and cheap alternatives. As the costs play a role in the product chosen, we compared standardized nicotine costs across products and countries. METHODS: We gathered prices of tobacco cigarettes, heated tobacco products (HTP), pharmaceutical nicotine replacement therapy (pNRT) gums, snus, and open and closed electronic nicotine delivery systems (ENDS) in 6 countries (Switzerland, Germany, USA, Sweden, France, UK) in 2019. We compared the cost of a pack of cigarettes in Switzerland to the cost of equivalent doses of nicotine delivered by other products and across countries, normalizing to purchasing power GDP per capita to compute relative adjusted costs (RACs). RESULTS: Adjusted tobacco cigarette cost was lowest in Switzerland, Germany, and Sweden; RAC for pNRT was 1.1 in Switzerland and 1.0 in Germany. In France and the UK, RACs for cigarettes were 1.5 and 2.1, while for pNRT they were cheaper (RAC: 0.04). In Switzerland, snus/nicotine pouches were the cheapest form of nicotine delivery (RAC: 0.2), open ENDS were a low-cost option for nicotine delivery in all countries (RAC: 0.2-0.3), and HTP cost more than regular tobacco products in most countries. CONCLUSIONS: We found broad differences in costs of nicotine according to countries and products. This should be considered in future studies on smoking prevalence and in public health efforts.

Long-term effects of systematic smoking cessation counselling during acute coronary syndrome, a multicentre before-after study.

TRIAL DESIGN: In the Special Program University Medicine-Acute Coronary Syndromes (SPUM-ACS) observational study (clinical trial registration: NCT01000701), a multicentre before-after clinical trial, we assessed 5-year outcome after acute coronary syndrome, comparing a systematic with an opportunistic smoking cessation counselling phase. METHODS: We studied smokers who were hospitalised for acute coronary syndromes (ACS), and we assessed self-reported smoking cessation, incidence of cardiovascular events and mortality 5 years after hospital discharge. In the observational phase, from August 2009 to October 2010, only smokers who requested smoking cessation counselling received it during hospitalisation. In the interventional phase, from November 2010 to February 2012, hospitalised smokers with ACS were systematically offered intensive smoking cessation counselling including four telephone calls within 2 months of discharge. Because of the before-after design, the care givers were aware of study phase. The objective was to assess whether systematic counselling to every smoker with ACS has an impact on the long-term smoking cessation rate, incidence of cardiovascular events and mortality. Missing data on smoking cessation were analysed with multiple imputation. The study was not powered to assess differences in 5-year smoking cessation rates or cardiovascular outcomes. RESULTS: Overall, 458 smokers with ACS were included at baseline (225 during the intervention phase and 233 during the observation phase). At 5 years, 286 (62.4%) reported their smoking status (140 for the intervention phase and 146 for the observation phase) and 51 (11.1%) had died. There was no statistically significant difference in the abstinence rate between the interventional phase (75/140, 54%), and the observational phase (68/146, 47%), with a risk ratio with multiple imputation adjusted for age, sex, education and ACS type of 1.13 (95% confidence interval [CI] 0.84-1.51, p = 0.4). The 5-year risk of major acute cardiovascular event was similar in the intervention phase as compared with the observational phase. The multivariate adjusted hazard ratio for all-cause mortality was 0.84 (95% CI 0.45-1.60, p = 0.6). CONCLUSIONS: In this controlled long-term interventional study, systematic intensive smoking cessation counselling in all hospitalised smokers with ACS did not increase 5-year smoking cessation rates, nor decrease cardiovascular event recurrence, as compared with opportunistic smoking cessation counselling during hospitalization.

Counseling in Vape Shops: A Survey of Vape Shop Managers in Switzerland.

Vaporizers (e-cigarettes) are the most common smoking cessation aids in Switzerland, but we do not know what information customers receive in vape shops. We surveyed vape-shop managers to find out what recommendations they make to their customers. An interdisciplinary group developed the questionnaire. Respondents self-reported their smoking history, demographics, and the recommendations they thought they would give to hypothetical customers in clinical vignettes. We also queried if they collaborated with health care professionals. Of those contacted, 53.8% (70/130) of vape-shop managers responded, and 52.3% (68/130) were included in the final analysis. Managers were mostly male and ex-smokers who switched to vaporizers; 60.3% would encourage a hypothetical smoker with high nicotine dependence to start with the highest possible nicotine concentration when switching to vaporizers. For this smoker, 36.9% would recommend high (≥15 mg/mL), 32.3% medium (6-14 mg/mL), and 3.1% low (1-5 mg/mL) nicotine concentrations. The rest adapted their recommendations to fit the customer or device; 76.5% reported that physicians referred customers to them, and 78.8% would attend a course given by experts in the field of vaporizers and smoking cessation. Vape-shop managers varied widely in the recommendations they gave customers. Most reported ongoing collaboration with health care professionals and were interested in improving their counselling skills through training.

Correlating in situ RHEED and XRD to study growth dynamics of polytypism in nanowires.

Design of novel nanowire (NW) based semiconductor devices requires deep understanding and technological control of NW growth. Therefore, quantitative feedback over the structure evolution of the NW ensemble during growth is highly desirable. We analyse and compare the methodical potential of reflection high-energy electron diffraction (RHEED) and X-ray diffraction reciprocal space imaging (XRD) for in situ growth characterization during molecular-beam epitaxy (MBE). Simultaneously recorded in situ RHEED and in situ XRD intensities show strongly differing temporal behaviour and provide evidence of the highly complementary information value of both diffraction techniques. Exploiting the complementarity by a correlative data analysis presently offers the most comprehensive experimental access to the growth dynamics of statistical NW ensembles under standard MBE growth conditions. In particular, the combination of RHEED and XRD allows for translating quantitatively the time-resolved information into a height-resolved information on the crystalline structure without a priori assumptions on the growth model. Furthermore, we demonstrate, how careful analysis of in situ RHEED if supported by ex situ XRD and scanning electron microscopy (SEM), all usually available at conventional MBE laboratories, can also provide highly quantitative feedback on polytypism during growth allowing validation of current vapour-liquid-solid (VLS) growth models.

Cumulative Marijuana Use and Carotid Intima-Media Thickness at Middle Age: The CARDIA Study.

BACKGROUND: Long-term cardiovascular health effects of marijuana are understudied. Future cardiovascular disease is often indicated by subclinical atherosclerosis for which carotid intima-media thickness is an established parameter. METHODS: Using the data from the Coronary Artery Risk Development in Young Adults (CARDIA) study, a cohort of 5115 Black and white women and men at Year 20 visit, we studied the association between carotid intima-media thickness in midlife and lifetime exposure to marijuana (1 marijuana year = 365 days of use) and tobacco smoking (1 pack-year = 20 cigarettes/day for 365 days). We measured carotid intima-media thickness by ultrasound and defined high carotid intima-media thickness at the threshold of the 75th percentile of all examined participants. We fit logistic regression models stratified by tobacco smoking exposure, adjusting for demographics, cardiovascular risk factors, and other drug exposures. RESULTS: Data was complete for 3257 participants; 2722 (84%) reported ever marijuana use; 374 (11%) were current users; 1539 (47%) reported ever tobacco smoking; 610 (19%) were current smokers. Multivariable adjusted models showed no association between cumulative marijuana exposure and high carotid intima-media thickness in never or ever tobacco smokers, odds ratio (OR) 0.87 (95% confidence interval [CI]: 0.63-1.21) at 1 marijuana-year among never smokers and OR 1.11 (95% CI: 0.85-1.45) among ever tobacco smokers. Cumulative exposure to tobacco was strongly associated with high carotid intima-media thickness, OR 1.88 (95%CI: 1.20-2.94) for 20 pack-years of exposure. CONCLUSIONS: This study adds to the growing body of evidence that there might be no association between the average population level of marijuana use and subclinical atherosclerosis.

Association between self-reported motivation to quit smoking with effectiveness of smoking cessation intervention among patients hospitalized for acute coronary syndromes in Switzerland.

Guidelines recommend brief smoking cessation interventions for hospitalized smokers reporting low motivation-to-quit. However, an intensive smoking cessation intervention may improve smoking cessation for these smokers. We conducted a secondary analysis of a pre-post interventional study that tested the efficacy of a proactive approach systematically offering intensive smoking cessation intervention to all hospitalized smokers with acute coronary syndrome (ACS) compared to a reactive approach offering it only to smokers willing to quit. We analyzed data from one study site in Switzerland, which recorded motivation-to-quit smoking at study inclusion between 08.2009 and 02.2012. The primary outcome was smoking cessation at 1- and 5-year. We tested for interaction by participant's motivation-to-quit score (low vs. high motivation), and calculated multivariable adjusted risk ratios (RR), stratified by motivation score. We obtained motivation scores for 230 smokers. Follow-up was 94% (217/230) at 1-year and 68% (156/230) at 5-year. Among participants with low motivation to quit, 19% of smokers in the reactive phase had quit at 1 year compared to 50% of smokers in the proactive phase (multivariable adjusted RR = 2.85, 95%CI:0.91-8.91). Among highly motivated smokers, rates did not differ between phases: 48% vs. 49% (multivariable adjusted RR = 1.02, 95%CI:0.75-1.39, p-value for interaction between motivation-to-quit categories = 0.10). At 5-year follow-up, the point estimates were similar. While our study has limitations inherent to the study design and sample size, we found that a proactive approach to offer systematic smoking cessation counseling for smokers with ACS reporting low motivation to quit was associated with higher smoking cessation rates at 1 year.

Association between marijuana use and electrocardiographic abnormalities by middle age: the Coronary Artery Risk Development in Young Adults (CARDIA) study.

AIMS: To evaluate the prevalence of electrocardiogram (ECG) abnormalities in marijuana users as an indirect measure of subclinical cardiovascular disease (CVD). DESIGN: Longitudinal and cross-sectional secondary data analysis from the CARDIA (Coronary Artery Risk Development in Young Adults) study. SETTING: Four communities in the United States. PARTICIPANTS: A total of 2585 participants from the 5115 black and white men and women recruited at age 18-30 years in 1985 to 1986 in CARDIA. MEASUREMENTS: ECG abnormalities coded as minor and major abnormalities with the Minnesota code of electrocardiographic findings at year 20. Self-reported current (past 30 days) and computed cumulative life-time marijuana use (one 'marijuana-year' corresponds to 365 days of use) through assessments every 2-5 years. We fitted logistic regression models adjusting for sex, race, center, education, age, tobacco smoking, physical activity, alcohol use and body mass index. FINDINGS: Among the 2585 participants with an ECG at year 20, mean age was 46, 57% were women, 45% were black; 83% had past exposure to marijuana and 11% were using marijuana currently. One hundred and seventy-three participants (7%) had major abnormalities and 944 (37%) had minor abnormalities. Comparing current with never use in multivariable-adjusted models, the odds ratio (OR) for major ECG abnormalities was 0.60 [95% confidence interval (CI) = 0.32-1.15] and for minor ECG abnormalities 1.21 (95% CI = 0.87-1.68). Results did not change after stratifying by sex and race. Cumulative marijuana use was not associated with ECG abnormalities. CONCLUSION: In a middle-aged US population, life-time cumulative and occasional current marijuana use were not associated with increases in electrocardiogram abnormalities. This adds to the growing body of evidence that occasional marijuana use and cardiovascular disease events and markers of subclinical atherosclerosis are not associated.

Quantitative analysis of time-resolved RHEED during growth of vertical nanowires.

We present an approach for quantitative evaluation of time-resolved reflection high-energy electron diffraction (RHEED) intensity patterns measured during the growth of vertical, free-standing nanowires (NWs). The approach considers shadowing due to attenuation by absorption and extinction within the individual nanowires and estimates the time dependence of its influence on the RHEED signal of the nanowire ensemble as a function of instrumental RHEED parameters and the growth dynamics averaged over the nanowire ensemble. The developed RHEED simulation model takes into account the nanowire structure evolution related to essential growth aspects, such as axial growth, radial growth with tapering and facet growth, as well as so-called parasitic intergrowth on the substrate. It also considers the influence of the NW density, which turns out to be a sensitive parameter for the time-dependent interpretation of the intensity patterns. Finally, the application potential is demonstrated by evaluating experimental data obtained during molecular beam epitaxy (MBE) of self-catalysed GaAs nanowires. We demonstrate, how electron shadowing enables a time-resolved analysis of the crystal structure evolution at the top part of the growing NWs. The approach offers direct access to study growth dynamics of polytypism in nanowire ensembles at the growth front region under standard growth conditions.