Pathways to marijuana use among adolescents: cultural/ecological, family, peer, and personality influences

OBJECTIVE: To examine the linkages, cultural/ecological factors, and major psychosocial risk factors as they relate to drug use in a sample from Colombia, South America. METHOD: The participants were 1.687 adolescents living in mixed urban-rural communities in Colombia, South America. An individual interview was administered to youths in their homes by Colombian interviewers. The scales used were based on item intercorrelations grouped into the following risk categories: (1) adolescent personality, (2) family traits, (3) peer factors, and (4) cultural/ecological variables. RESULTS: Pearson correlations were computed for each variable and the frequency of marijuana use. Results show that each of the domains was related to adolescent marijuana use, with some notable gender differences. As regards the interrelation of domains, a mediational model was operative. CONCLUSIONS: Findings support a family interactional theory. The domains of family, personality, and peer factors had a direct effect on the adolescents' marijuana use. Implications for prevention are also addressed.     

Interferon alpha 2b as maintenance therapy in low grade malignant lymphoma improves duration of remission and survival

We assessed the efficacy and toxicity of interferon alpha 2b (IFN) as maintenance therapy in patients with low grade malignant lymphoma. Between March 1986 and December 1989, 98 patients with low-grade malignant lymphoma in complete remission after conventional chemotherapy were randomly assigned to received IFN, 5.0 MU three times a week for one year, as maintenance therapy (n = 48), or to receive no treatment (control group, n = 50). In March 1994, the median duration of response had not yet been reached in the patients treated with IFN compared to 46 months in the control group. At 9-years 62% of the patients in the IFN arm remain in first complete remission compared to only 25% in the control group (p <.001). In addition, the median duration of survival has not yet been reached in either the IFN arm compared to 74 months in the control group (p <.001). Quality of life was excellent in both groups and severe side effects secondary to IFN treatment were not observed. All patients completed the planned dose of IFN. We conclude that IFN as maintenance therapy in low-grade malignant lymphoma is an excellent therapeutic option because it improves the duration of remission and survival without producing severe side effects or reducing the quality of life.     

A GRASP metaheuristic to improve accessibility after a disaster

We consider the problem of allocating scarce resources to repair a rural road network after it has been damaged by a natural or man-made disaster. We propose a solution approach based on the GRASP and VNS metaheuristics that aims to maximize the accessibility of as many people as possible to the main cities or regional centers where the economic and social infrastructure is usually located. The efficiency of our approach is demonstrated by applying it to a set of small and medium size instances and to a large real-life motivated instance. Results point out the importance of OR techniques to support the disaster management decision process operations, particularly during the recovery phase.     

Efficacy of reciprocating systems for removing root filling material plus complementary cleaning methods in flattened canals: Microtomography and scanning electron microscopy study

The aim of this study was to evaluate three reciprocating systems and complementary cleaning methods on filling material removal during retreatment of flattened canals. Thirty‐six mandibular incisors were prepared using rotary instruments up to size 25.08 and filled using the single‐cone technique. Subsequently, the teeth were divided into three groups (n = 12) according to retreatment procedures: Reciproc Blue (RB): 25/0.08 and 40/0.06; ProDesign R (PDR): 25/0.06 and 35/0.05; and WaveOne Gold (WOG): 25/0.07 and 35/0.06. The remaining filling volume materials were assessed by means of micro‐CT imaging before and after retreatment. After this, the specimens were subdivided into three groups according to complementary cleaning methods: XP‐Endo Shaper (30/0.01); passive ultrasonic irrigation (PUI); 60° oscillatory instrumentation with #30 H‐file, and micro‐CT scan was taken. Then, the roots were cut in half and the samples were analyzed by scanning electron microscope (SEM). The data were analyzed statistically using Kruskal–Wallis and Dunn's Multiple Comparison test with significance level of 5%. None of the reciprocating files promoted complete removal of filling material and there was no statistical difference between the groups, regardless instrument size (p > 0.05). Complementary cleaning methods increased remnant filling removal (p < 0.05). XP‐endo Shaper significantly reduced the amount of filling material in the apical and middle thirds, compared with H‐files (p < 0.05), with no difference with PUI. In the SEM, there was no statistical difference among the instruments (p > 0.05). The reciprocating systems showed similar effectiveness in removing root filling material. Complementary cleaning method with the XP‐Shaper enhanced filling material removal.     

Assessing trends in Duane plots using robust fits

The Duane plot is a simple and widely used graphical technique in the analysis of repairable systems. The fitting of a straight line to points in that graph serves to determine the behavior of the system assuming a power law process. However, the classical least squares fitting suffer from lack of robustness and it is specially heavily affected by the more remote and perhaps least interesting points. In order to solve this drawback we propose a robust fit based on Least Median of Squares (LMS) or Least Trimmed Squares (LTS) regression estimators of [1].This methodology has been applied in a project aimed to study the reliability, availability and maintainability of the aerial contact line of the Spanish railways.     

Effect of time and ultrasonic activation on ethylenediaminetetraacetic acid on smear layer removal of the root canal

The aim of this study was to assess the effect of time and the ultrasonic activation of ethylenediaminetetraacetic acid (EDTA) in removing the smear layer of at root canal. A total of 60 bovine inferior incisors were transversely sectioned and instrumented; A smear layer was added in the root dentin surface. The specimen were then divided into six groups according to the following final irrigation protocols: Group (G) 1: conventional irrigation with sodium hypochlorite (NaOCl); G2: conventional irrigation with NaOCl + EDTA for 20 s; G3: conventional irrigation with NaOCl + EDTA for 60 s; G4: passive ultrasonic irrigation (PUI) with NaOCl; G5: PUI with NaOCl + PUI with EDTA for 20 s; G6: PUI + NaOCl and PUI with EDTA for 60 s. Samples were analyzed by scanning electron microscope (SEM) at ×500 increase. The images were measured by three blinded evaluators and classified in scores ranging from 1 to 5. The results were analyzed by the Pearson correlation test and the ANOVA nonparametric Kruskal–Wallis and Dunn's tests were used for the comparisons. Irrigated samples only with NaOCl (G1 and G4) had higher scores when compared with other groups. G5 and G6, irrigated with 17% EDTA and ultrasonic irrigation had lower scores. However, there was no statistically significant difference in G2 and G3, where there was no irrigation. It was concluded that irrigation with 17% EDTA for 20 s promoted the effective removal of smear layer, regardless of ultrasonic irrigation.     

Making the most of TV on the move: My newschannel

The increasing success of mobile-TV (m-TV) is changing the habits and customs in TV consumption which now extends to parts of the day when viewers are not at home and, mainly, within short intervals between other daily activities. Since much m-TV consumption will be in spare time, offering the users contents they are interested in becomes extremely important to provide an attractive service which does not discourage potential users. Using DVB-H as transport infrastructure, in this paper we introduce a personalization architecture which perfectly fits in with the value chain of m-TV. By applying semantic models and techniques, personalized virtual channels are dynamically constructed by adequately combining several kinds of contents according to the user’s interests. While the personalization architecture is particularized, in this paper, to provide news channels, it could be easily generalized to other fields.