Low-cycle fatigue behavior of flexible 3D printed thermoplastic polyurethane blends for thermal energy storage/release applications

Thermal energy storage (TES) materials constituted by a microencapsulated paraffin having a melting temperature of 6°C and a thermoplastic polyurethane (TPU) matrix were prepared through fused deposition modeling. Scanning electron microscope (SEM) micrographs demonstrated that the microcapsules were homogeneously distributed within the matrix, with a rather good adhesion within the layers of 3D printed specimens, even at elevated concentrations of microcapsules. The presence of paraffin capsules having a rigid polymer shell lead to a stiffness increase, associated to a decrease in the stress and in the strain at break. Tensile and compressive low-cycles fatigue tests showed that the presence of microcapsules negatively affected the fatigue resistance of the samples, and that the main part of the damage occurred in the first fatigue cycles. After the first 10 loading cycles at 50% of the stress at break, a decrease in the elastic modulus ranging from 60% for neat TPU to 80% for composite materials was detected. This decrease reached 40% of the original value at 90% of the stress at break after 10 cycles. Differential scanning calorimetry tests on specimens after fatigue loading highlighted a substantial retention of the original TES capability, in the range of 80%–90% of the pristine value, even after 1000 cycles, indicating that the integrity of the capsules was maintained and that the propagation of damage during fatigue tests took probably place within the surrounding polymer matrix. It could be therefore concluded that it is possible to apply the developed blends in applications where the materials are subjected to cyclic stresses, both in tensile and compressive mode.     

Free-Sets: A Condensed Representation of Boolean Data for the Approximation of Frequency Queries

Given a large collection of transactions containing items, a basic common data mining problem is to extract the so-called frequent itemsets (i.e., sets of items appearing in at least a given number of transactions). In this paper, we propose a structure called free-sets, from which we can approximate any itemset support (i.e., the number of transactions containing the itemset) and we formalize this notion in the framework of -adequate representations (H. Mannila and H. Toivonen, 1996. In Proc. of the Second International Conference on Knowledge Discovery and Data Mining (KDD'96), pp. 189–194). We show that frequent free-sets can be efficiently extracted using pruning strategies developed for frequent itemset discovery, and that they can be used to approximate the support of any frequent itemset. Experiments on real dense data sets show a significant reduction of the size of the output when compared with standard frequent itemset extraction. Furthermore, the experiments show that the extraction of frequent free-sets is still possible when the extraction of frequent itemsets becomes intractable, and that the supports of the frequent free-sets can be used to approximate very closely the supports of the frequent itemsets. Finally, we consider the effect of this approximation on association rules (a popular kind of patterns that can be derived from frequent itemsets) and show that the corresponding errors remain very low in practice.     

Efficacy of a smoking cessation program for hospital patients

BACKGROUND: Hospitalization may be an opportune time to change smoking behavior because it requires smokers to abstain from tobacco at the same time that illness can motivate them to quit. A hospital-based intervention may promote smoking cessation after discharge. METHODS: We tested the efficacy of a brief bedside smoking counseling program in a randomized controlled trial at Massachusetts General Hospital, Boston. The 650 adult smokers admitted to the medical and surgical services were randomly assigned to receive usual care or a hospital-based smoking intervention consisting of (1) a 15-minute bedside counseling session, (2) written self-help material, (3) a chart prompt reminding physicians to advise smoking cessation, and (4) up to 3 weekly counseling telephone calls after discharge. Smoking status was assessed 1 and 6 months after hospital discharge by self-report and validated at 6 months by measurement of saliva cotinine levels. RESULTS: One month after discharge, more intervention than control patients were not smoking (28.9% vs 18.9%; P=.003). The effect persisted after multiple logistic regression analyses adjusted for baseline group differences, length of stay, postdischarge smoking treatment, and hospital readmission (adjusted odds ratio, 2.19; 95% confidence interval, 1.34-3.57). At 6 months, the intervention and control groups did not differ in smoking cessation rate by self-report (17.3% vs 14.0%; P=.26) or biochemical validation (8.1% vs 8.7%; P=.72), although the program appeared to be effective among the 167 patients who had not previously tried to quit smoking (15.3% vs 3.7%; P=.01). CONCLUSIONS: A low-intensity, hospital-based smoking cessation program increased smoking cessation rates for 1 month after discharge but did not lead to long-term tobacco abstinence. A longer period of telephone contact after discharge might build on this initial success to produce permanent smoking cessation among hospitalized smokers.     

The effect of enforcing tobacco-sales laws on adolescents' access to tobacco and smoking behavior

BACKGROUND: Enforcing laws banning tobacco sales to minors is widely advocated as a way to reduce young people's access to tobacco and tobacco use. Whether this approach is successful is not known. METHODS: In a two-year controlled study, we assessed sales of tobacco to minors and young people's access to and use of tobacco in six Massachusetts communities. Three communities (the intervention group) enforced tobacco-sales laws, whereas three matched communities (the control group) did not. To assess compliance with the law, minors working for the study investigators attempted to purchase tobacco from all retail vendors in each community every six months. Three annual anonymous surveys of a total of 22,021 students in grades 9 through 12 (response rate, 84 percent) measured access to tobacco and smoking behavior. RESULTS: At base line, 68 percent of 487 vendors sold tobacco to minors. Compliance with the law improved significantly faster in the intervention communities than in the controls (P<0.001). By the study's end, 82 percent of the merchants in the intervention communities complied with the law, as compared with 45 percent in the control communities (P<0.001). However, adolescents under 18 years old reported only a small drop in their ability to purchase tobacco and no decline in its use. Communities with and those without enforcement programs did not differ with respect to these outcomes. CONCLUSIONS: Enforcing tobacco-sales laws improved merchants' compliance and reduced illegal sales to minors but did not alter adolescents' perceived access to tobacco or their smoking. Test purchases of tobacco do not accurately reflect adolescents' self-reported access to tobacco, and reducing illegal sales to less than 20 percent of attempts -- the goal of a new federal law-- may not decrease young people's access to or use of tobacco.     

Impediments to the enforcement of youth access laws

OBJECTIVE: To recognise obstacles to the implementation of the effective enforcement of tobacco sales laws and to identify measures that could be taken to overcome these obstacles. DESIGN: Interviews were conducted with health department officials in Massachusetts communities to determine why their efforts to prevent illegal sales of tobacco to minors had been only partially successful. SETTING: Urban, suburban, and rural communities in Massachusetts, USA. RESULTS: Organisational problems, court challenges to citations, budgetary threats, and political pressure all combined to reduce the frequency of enforcement inspections to half the intended rate. Political pressure resulted in the exclusion of older youths from compliance tests, further undermining enforcement efficacy. CONCLUSIONS: Suggestions for addressing the problems include obtaining support from the community, keeping elected and court officials informed about plans for merchant education and law enforcement, using efficient enforcement protocols, setting merchant compliance goals, and advising the public and government officials about progress towards those goals, using older youths to make purchase attempts, and testing all merchants frequently.     

Effect of local restaurant smoking regulations on progression to established smoking among youths

Background: While smoke-free restaurant laws are intended to protect the public from secondhand smoke exposure, they may also discourage smoking among adolescents. There is no evidence from longitudinal studies to test this hypothesis. Objective: To examine the effect of local restaurant smoking regulations on progression to established smoking among adolescents. Design, setting, and subjects: A cohort of 2623 Massachusetts youths, ages 12–17 years at baseline, was interviewed via random digit dial telephone survey in 2001–2002 and followed up two years later. A generalised estimating equations (GEE) logistic regression analysis was used and controlled for potential individual, household, and town level confounding factors. Main outcome measure: Progression to established smoking during the two year follow up period (defined as having smoked 100 or more cigarettes in one''s life). Results: Compared to youths living in towns with weak regulations, those living in towns with strong regulations (complete restaurant smoking bans) had less than half the odds of progression to established smoking (odds ratio (OR) 0.39, 95% confidence interval (CI) 0.24 to 0.66). The association was stronger for youths in towns with strong regulations in effect for two or more years (OR 0.11, 95% CI 0.03 to 0.37), although it was still present for those in towns with strong regulations in effect for less than two years (OR 0.55, 95% CI 0.33 to 0.90). No relationship was found between living in a town with a medium restaurant smoking regulation (restriction of smoking to enclosed, separately ventilated areas) and rates of progression to established smoking. Conclusions: Local restaurant smoking bans may be an effective intervention to prevent youth smoking.     

Evolutionary subspace clustering using variable genome length

Subspace clustering is a data-mining task that groups similar data objects and at the same time searches the subspaces where similarities appear. For this reason, subspace clustering is recognized as more general and complicated than standard clustering. In this article, we present ChameleoClust+, a bioinspired evolutionary subspace clustering algorithm that takes advantage of an evolvable genome structure to detect various numbers of clusters located in different subspaces. ChameleoClust+ incorporates several biolike features such as a variable genome length, both functional and nonfunctional elements, and mutation operators including large rearrangements. It was assessed and compared with the state-of-the-art methods on a reference benchmark using both real-world and synthetic data sets. Although other algorithms may need complex parameter settings, ChameleoClust+ needs to set only one subspace clustering ad hoc and intuitive parameter: the maximal number of clusters. The remaining parameters of ChameleoClust+ are related to the evolution strategy (eg, population size, mutation rate), and a single setting for all of them turned out to be effective for all the benchmark data sets. A sensitivity analysis has also been carried out to study the impact of each parameter on the subspace clustering quality.     

Irritation at school: Reasons to initiate strain management earlier.

Organizational research provides many tested stressor–strain relationships in the workforce. To a lesser extent, it has been researched whether strain may already be present before the commencement of employment. The final years of school may be experienced as straining, because the need to perform well to obtain further education and, therefore, job opportunities, is often intense. To explore this, a scale measuring irritation, a well-documented concept of psychological strain at work, was adapted to the situation of school adolescents. Samples from 2 Swiss schools (n = 1,310 and n = 301) were obtained to study (a) the reliability of the adapted irritation scale, (b) the relationships between school stressors and irritation, (c) the moderating influences of self-efficacy on the relationship between stressors and irritation, and (d) the mediating effect of irritation in the relationship between stressors and other psychological impairments. These hypotheses were in line with results from organizational stress research. Results indicate the same mechanisms at play as those found in occupational stress research studies and implications with regard to stress interventions at school are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Students' opinion of tobacco control policies recommended for US colleges: a national survey

Objective: Comprehensive tobacco control policies for US colleges and universities have been proposed by several groups in order to counter the rising use of tobacco by students enrolled in these institutions. Student opinion of these policies is not known, and concern about student opposition is one barrier that deters administrators from adopting the policies. This study measured student support for recommended college tobacco control policies.

Design: Mailed survey of US college students (2001 Harvard School of Public Health College Alcohol Study).

Setting: 119 nationally representative, four-year colleges and universities in the USA.

Participants: 10 904 randomly selected undergraduate students enrolled at participating schools.

Main outcome measures: Students' opinion of 7 proposed tobacco control policies.

Results: A majority of students supported each policy. Over three quarters of students favoured smoke-free policies for all college buildings, residences, and dining areas, while 71% supported prohibiting tobacco advertising and sponsorship of campus social events, 59% favoured prohibiting tobacco sales on campus, and 51% supported smoke-free campus bars. All policies had more support among non-smokers than smokers (p < 0.001). Among smokers, support for policies was inversely related to intention to quit and intensity of tobacco consumption. Because college students' tobacco consumption is low, a majority of smokers favoured banning smoking in college buildings and dining areas and prohibiting tobacco marketing on campus.

Conclusions: Student support for proposed campus tobacco control policies is strong, even among smokers, and broadly based across demographic subgroups. These findings should provide reassurance to college administrators who are considering adopting these policies.