Smoking, smoking cessation and smoking relapse patterns: a web-based survey of current and former smokers in the US.

AIM: The aim of this study was to characterise the natural course of smoking cessation behaviour in a web-based survey of current and former cigarette smokers (CS and FS) in the United States. METHODS: A web-based survey of CS and FS was conducted in April 2009; demographic and socioeconomic characteristics and smoking history (including the number of lifetime and length of latest quit attempts, aids used and time to relapse) were collated. The surveyed cohort was selected from prescreened CS and FS panellists and matched for age, race and education, to be representative of the US population. Descriptive statistics and time-to-event analyses using Kaplan-Meier curves were applied in the analysis of this report. RESULTS: The final cohort comprised 512 CS and 566 FS (n = 1078). A larger proportion of FS than CS reported a longest smoke-free period of > 1 year (78.8% vs. 22.4%, respectively). As a greater variety of smoking cessation products became available over time, the proportion of unassisted quit attempts decreased from 76.1% prior to 1983 to 43.9% after 2006 for CS and from 79.3% to 50.3% for FS. The cumulative proportion of subjects relapsing was 31.3% by 1 week and 79.3% by 6 months. The estimated median time to next quit attempt was approximately 360 days. CONCLUSIONS: These data confirm that relapse is common and that as the variety of cessation modalities increase, the proportion of unassisted quit attempts decreases. Self-help or cold-turkey methods still provide significant alternatives even when pharmacotherapy is available. This study provides data related to the smoking history and smoking cessation patterns of a large, nationally representative sample of CS and FS.

Lung function and respiratory symptoms in a 1-year randomized smoking cessation trial of varenicline in COPD patients.

UNLABELLED: There are few data concerning changes in lung function and respiratory symptoms in smokers with chronic obstructive pulmonary disease (COPD) weeks to months after quitting smoking. We examined serial changes in spirometry and Clinical COPD Questionnaire (CCQ) scores (measuring respiratory symptoms and health-related quality of life) in COPD participants by smoking status during a smoking cessation trial. In this randomized, double-blind trial, smokers with mild-to-moderate COPD were treated with varenicline 1 mg b.i.d. or placebo for 12 weeks and followed to Week 52. Primary endpoints of abstinence were previously reported. Secondary endpoints were mean changes from baseline in post-bronchodilator forced expired volume in 1 s (FEV(1)) and CCQ scores. Change from baseline in post-bronchodilator FEV(1) was significantly improved in continuous abstainers (121.8 mL) vs. continuous smokers (37.9 mL) at Week 12 (P = 0.0069), but not at Weeks 24 or 52. Mean change from baseline at Week 12 in CCQ Total Score was significantly better in continuous abstainers (-1.04) vs. continuous smokers (-0.53; P < 0.0001): this improvement was sustained at Weeks 24 and 52. In a 1-year cessation trial of smokers with COPD, continuous abstinence compared with continuous smoking significantly improved post-bronchodilator FEV(1) at Week 12 (although the difference narrowed subsequently) and CCQ Total Scores at Week 12, with sustained improvement thereafter. ( TRIAL REGISTRY: http://www.clinicaltrials.gov; trial identifier: NCT00285012).

Measurement of distributed losses in optical waveguides: a new technique.

An accurate measurement method for waveguide loss measurement is reported which is suitable for the determination of low values of distributed loss in integrated optical waveguides. The technique is insensitive to the values of other circuit characteristics such as splitter loss and splitting ratio; indeed it provides a means of evaluating most relevant circuit parameters. The concept is demonstrated through the use of discrete single-mode fiber optical components, and it is shown that the method is capable of generating repeatable measurements of waveguide loss with good accuracy.

Effect of weak magnetic fields on growth of cells in tissue culture.

Normal Chinese hamster V79 cells were grown in vitro for more than one year in a magnetic field of 10(-7) tesla to test recently hypothesized effects of weak magnetic fields on biological systems. No significant difference was observed between growth rate in such fields and that in the ambient geomagnetic field.

Ray trajectories in optical fiber tapered sections.

Slab waveguide tapers with finite cladding thickness are analyzed using a geometrical optics approach, and the results are compared with an exact modal analysis. Iteration formulas are derived for the calculation of the propagation angles of the guided modes and the corresponding changes in the core and cladding thicknesses, assuming that the difference between the refractive indexes of the core and cladding is small. Numerical results are presented and compared with the values obtained by a successive step modal analysis, showing good agreement between the two approaches. This indicates that ray tracing techniques should be useful for the analysis and design of taper couplers.