The use of electronic cigarettes is growing, and some hope that they will replace what is felt to be the more dangerous nicotine-delivery system — cigarettes. However, data on the long-term safety of ...e-cigarettes are still being gathered.
Electronic cigarettes (e-cigarettes), also known as electronic nicotine-delivery systems, are devices that produce an aerosol by heating a liquid that contains a solvent (vegetable glycerin, propylene glycol, or a mixture of these), one or more flavorings, and nicotine, although the nicotine may be omitted. The evaporation of the liquid at the heating element is followed by rapid cooling to form an aerosol. This process is fundamentally different from the combustion of tobacco, and consequently the composition of the aerosol from e-cigarettes and the smoke from tobacco is quite different. E-cigarette aerosol is directly inhaled (or “vaped”) by the user through . . .
In a previously published controlled trial, maternal administration of vitamin D during pregnancy was found to protect against wheeze in the offspring at the age of 3 years. In this follow-up study ...involving the same children at the age of 6 years, that supplementation no longer had a protective effect.
In this paper, a direct writing method for gallium‐indium alloys is presented. The relationships between nozzle inner diameter, standoff distance, flow rate, and the resulting trace geometry are ...demonstrated. The interaction between the gallium oxide layer and the substrate is critically important in understanding the printing behavior of the liquid metal. The difference between receding and advancing contact angles demonstrates that the adhesion of the oxide layer to the substrate surface is stronger than the wetting of the surface by the gallium‐indium alloy. This further demonstrates why free‐standing structures such as the traces described herein can be realized. In addition to the basic characterization of the direct writing process, a design algorithm that is generalizable to a range of trace geometries is developed. This method is applied to the fabrication of an elastomer‐encapsulated strain gauge that displays an approximately linear behavior through 50% strain with a gauge factor of 1.5.
A novel method for directly writing liquid gallium‐indium alloy is presented. In addition to the basic characterization of the direct writing process, a design algorithm for process stability is also developed. The method is employed to fabricate a strain gauge exhibiting an approximately linear behavior through strains of 50% with a gauge factor of 1.5.
The prevalence of tobacco smoking in the United States has declined to 14.0% but still exceeds 25% among high-risk subgroups.
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Electronic cigarettes (e-cigarettes) are not approved by the Food and ...Drug Administration (FDA) for smoking cessation, but Americans trying to quit smoking use these products more frequently than FDA-approved cessation aids.
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Comparative-effectiveness trials are needed to learn whether smokers have a better chance of quitting with e-cigarettes. Previous trials have had methodologic shortcomings, used first-generation e-cigarettes, or did not assess long-term outcomes. Hajek et al.
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now report in the
Journal
the results of a multicenter, pragmatic, randomized trial of e-cigarettes, . . .
The colonic microbiota plays an important role in human digestive physiology and makes a significant contribution to homeostasis in the large bowel. The microbiome probably comprises thousands of ...different bacterial species. The principal metabolic activities of colonic microorganisms are associated with carbohydrate and protein digestion. Nutrients of dietary and host origin support the growth of intestinal organisms. Short-chain fatty acids (SCFAs), predominantly acetate, propionate, and butyrate, are the principal metabolites generated during the catabolism of carbohydrates and proteins. In contrast, protein digestion yields a greater diversity of end products, including SCFAs, amines, phenols, indoles, thiols, CO2, H2, and H2S, many of which have toxic properties. The majority of SCFAs are absorbed from the gut and metabolized in various body tissues, making a relatively small but significant contribution to the body's daily energy requirements. Carbohydrate fermentation is, for the most part, a beneficial process in the large gut, because the growth of saccharolytic bacteria stimulates their requirements for toxic products associated with putrefaction, for incorporation into cellular proteins, thereby protecting the host. However, as digestive materials move along the gut, carbohydrates become depleted, which may be linked to the increased prevalence of colonic disease in the distal bowel.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Materials and systems that statically reflect radiation in the infrared region of the electromagnetic spectrum underpin the performance of many entrenched technologies, including building insulation, ...energy-conserving windows, spacecraft components, electronics shielding, container packaging, protective clothing, and camouflage platforms. The development of their adaptive variants, in which the infrared-reflecting properties dynamically change in response to external stimuli, has emerged as an important unmet scientific challenge. By drawing inspiration from cephalopod skin, we developed adaptive infrared-reflecting platforms that feature a simple actuation mechanism, low working temperature, tunable spectral range, weak angular dependence, fast response, stability to repeated cycling, amenability to patterning and multiplexing, autonomous operation, robust mechanical properties, and straightforward manufacturability. Our findings may open opportunities for infrared camouflage and other technologies that regulate infrared radiation.
IMPORTANCE: Chronic lung diseases are a leading cause of morbidity and mortality. Unlike chronic obstructive pulmonary disease, clinical outcomes associated with proportional reductions in expiratory ...lung volumes without obstruction, otherwise known as preserved ratio impaired spirometry (PRISm), are poorly understood. OBJECTIVE: To examine the prevalence, correlates, and clinical outcomes associated with PRISm in US adults. DESIGN, SETTING, AND PARTICIPANTS: The National Heart, Lung, and Blood Institute (NHLBI) Pooled Cohorts Study was a retrospective study with harmonized pooled data from 9 US general population-based cohorts (enrollment, 65 251 participants aged 18 to 102 years of whom 53 701 participants had valid baseline lung function) conducted from 1971-2011 (final follow-up, December 2018). EXPOSURES: Participants were categorized into mutually exclusive groups by baseline lung function. PRISm was defined as the ratio of forced expiratory volume in the first second to forced vital capacity (FEV1:FVC) greater than or equal to 0.70 and FEV1 less than 80% predicted; obstructive spirometry FEV1:FVC ratio of less than 0.70; and normal spirometry FEV1:FVC ratio greater than or equal to 0.7 and FEV1 greater than or equal to 80% predicted. MAIN OUTCOMES AND MEASURES: Main outcomes were all-cause mortality, respiratory-related mortality, coronary heart disease (CHD)–related mortality, respiratory-related events (hospitalizations and mortality), and CHD-related events (hospitalizations and mortality) classified by adjudication or validated administrative criteria. Absolute risks were adjusted for age and smoking status. Poisson and Cox proportional hazards models comparing PRISm vs normal spirometry were adjusted for age, sex, race and ethnicity, education, body mass index, smoking status, cohort, and comorbidities. RESULTS: Among all participants (mean SD age, 53.2 15.8 years, 56.4% women, 48.5% never-smokers), 4582 (8.5%) had PRISm. The presence of PRISm relative to normal spirometry was significantly associated with obesity (prevalence, 48.3% vs 31.4%; prevalence ratio PR, 1.68 95% CI, 1.55-1.82), underweight (prevalence, 1.4% vs 1.0%; PR, 2.20 95% CI, 1.72-2.82), female sex (prevalence, 60.3% vs 59.0%; PR, 1.07 95% CI, 1.01-1.13), and current smoking (prevalence, 25.2% vs 17.5%; PR, 1.33 95% CI, 1.22-1.45). PRISm, compared with normal spirometry, was significantly associated with greater all-cause mortality (29.6/1000 person-years vs 18.0/1000 person-years; difference, 11.6/1000 person-years 95% CI, 10.0-13.1; adjusted hazard ratio HR, 1.50 95% CI, 1.42-1.59), respiratory-related mortality (2.1/1000 person-years vs 1.0/1000 person-years; difference, 1.1/1000 person-years 95% CI, 0.7-1.6; adjusted HR, 1.95 95% CI, 1.54-2.48), CHD-related mortality (5.4/1000 person-years vs 2.6/1000 person-years; difference, 2.7/1000 person-years 95% CI, 2.1-3.4; adjusted HR, 1.55 95% CI, 1.36-1.77), respiratory-related events (12.2/1000 person-years vs 6.0/1000 person-years; difference, 6.2/1000 person-years 95% CI, 4.9-7.5; adjusted HR, 1.90 95% CI, 1.69-2.14), and CHD-related events (11.7/1000 person-years vs 7.0/1000 person-years; difference, 4.7/1000 person-years 95% CI, 3.7-5.8; adjusted HR, 1.30 95% CI, 1.18-1.42). CONCLUSIONS AND RELEVANCE: In a large, population-based sample of US adults, baseline PRISm, compared with normal spirometry, was associated with a small but statistically significant increased risk for mortality and adverse cardiovascular and respiratory outcomes. Further research is needed to explore whether this association is causal.
IMPORTANCE: According to numerous current guidelines, the diagnosis of chronic obstructive pulmonary disease (COPD) requires a ratio of the forced expiratory volume in the first second to the forced ...vital capacity (FEV1:FVC) of less than 0.70, yet this fixed threshold is based on expert opinion and remains controversial. OBJECTIVE: To determine the discriminative accuracy of various FEV1:FVC fixed thresholds for predicting COPD-related hospitalization and mortality. DESIGN, SETTING, AND PARTICIPANTS: The National Heart, Lung, and Blood Institute (NHLBI) Pooled Cohorts Study harmonized and pooled data from 4 US general population–based cohorts (Atherosclerosis Risk in Communities Study; Cardiovascular Health Study; Health, Aging, and Body Composition Study; and Multi-Ethnic Study of Atherosclerosis). Participants aged 45 to 102 years were enrolled from 1987 to 2000 and received follow-up longitudinally through 2016. EXPOSURES: Presence of airflow obstruction, which was defined by a baseline FEV1:FVC less than a range of fixed thresholds (0.75 to 0.65) or less than the lower limit of normal as defined by Global Lung Initiative reference equations (LLN). MAIN OUTCOMES AND MEASURES: The primary outcome was a composite of COPD hospitalization and COPD-related mortality, defined by adjudication or administrative criteria. The optimal fixed FEV1:FVC threshold was defined by the best discrimination for these COPD-related events as indexed using the Harrell C statistic from unadjusted Cox proportional hazards models. Differences in C statistics were compared with respect to less than 0.70 and less than LLN thresholds using a nonparametric approach. RESULTS: Among 24 207 adults in the pooled cohort (mean SD age at enrollment, 63 10.5 years; 12 990 54% women; 16 794 69% non-Hispanic white; 15 181 63% ever smokers), complete follow-up was available for 11 077 (77%) at 15 years. During a median follow-up of 15 years, 3925 participants experienced COPD-related events over 340 757 person-years of follow-up (incidence density rate, 11.5 per 1000 person-years), including 3563 COPD-related hospitalizations and 447 COPD-related deaths. With respect to discrimination of COPD-related events, the optimal fixed threshold (0.71; C statistic for optimal fixed threshold, 0.696) was not significantly different from the 0.70 threshold (difference, 0.001 95% CI, −0.002 to 0.004) but was more accurate than the LLN threshold (difference, 0.034 95% CI, 0.028 to 0.041). The 0.70 threshold provided optimal discrimination in the subgroup analysis of ever smokers and in adjusted models. CONCLUSIONS AND RELEVANCE: Defining airflow obstruction as FEV1:FVC less than 0.70 provided discrimination of COPD-related hospitalization and mortality that was not significantly different or was more accurate than other fixed thresholds and the LLN. These results support the use of FEV1:FVC less than 0.70 to identify individuals at risk of clinically significant COPD.
Present-day smuggling across the U.S.-Mexico border is a professional, often violent, criminal activity. However, it is only the latest chapter in a history of illicit business dealings that ...stretches back to 1848, when attempts by Mexico and the United States to tax commerce across the Rio Grande upset local trade and caused popular resentment. Rather than acquiesce to what they regarded as arbitrary trade regulations, borderlanders continued to cross goods and accepted many forms of smuggling as just. In Border Contraband, George T. Díaz provides the first history of the common, yet little studied, practice of smuggling across the U.S.-Mexico border. In Part I, he examines the period between 1848 and 1910, when the United States’ and Mexico’s trade concerns focused on tariff collection and on borderlanders’ attempts to avoid paying tariffs by smuggling. Part II begins with the onset of the Mexican Revolution in 1910, when national customs and other security forces on the border shifted their emphasis to the interdiction of prohibited items (particularly guns and drugs) that threatened the state. Díaz’s pioneering research explains how greater restrictions have transformed smuggling from a low-level mundane activity, widely accepted and still routinely practiced, into a highly profitable professional criminal enterprise.
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