167 research outputs found
Determinants of Seeking Treatment for Cocaine Abuse: A Case-Control Study
No full textThe objective of this study, which targeted long-term socially integrated cocaine users (in powder form, no heroin), was to analyze potential determinants of request for treatment for primary cocaine abuse. Two hundred and twenty-three cases (users who sought treatment for primary cocaine abuse) and 223 controls (users who did not seek treatment) were interviewed in Italy. A semistructured interview was created. Conditional logistic regression models were used. Cases had begun consuming illicit substances later, started using cocaine quicker, had high-risk drinking habits, had more intense recent use of cocaine, and used alone and at work. Some of the motivations of use that characterize subjects who seek treatment (to experience a 'high', disinhibition, avoidance, and to feel more confident) seem specifically to obtain immediate gratification, without concern for future consequences. Variability in cocaine abusers seeking treatment has been a long-recognized feature of this population and the results show that the appropriate target population (cocaine users experiencing problems and using more frequently) is reached by treatment services
Uno studio sulla mortalità dei soggetti segnalati alla Prefettura per uso di cannabis
No full textstudio epidemiologico sulla mortalità dei soggetti abusatori di cannabis e seganalati alla prefettura. confronto tra soggetti con sola cannabis e soggetti con poliabuso. I risultati dello studio evidenziano un elevato rischio di decesso per i consumatori di cannabis
Feasibility study of mini RF-helicon-Double-Layer plasma thruster for microsatelite attitude control
No full textThrusters for micro satellite are currently developed mainly based on FEEP Hall effect concepts and PPTS. This paper is focused on an innovative type of thruster firstly proposed by Australian National University (ANU) based on helicon plasma source and Double-layer effect. The study has been focused on establishing the performances of the helicon thruster in the low power regime ( <40 W) in term of thruster and specific impulse to verify the possibility of using it as actuators for microsatellite attitude control subsystem.
The paper deals with the possibility of applying the helicon Double-Layer thruster, as experimental payload, to the attitude control system of a UNISAT microsatellite in order to evaluate its effective performances. A model of the thruster has firstly been built, control algorithms for achievable maneuvers have been identified combining the thruster model with the UNISAT attitude dynamics model.
UNISAT satellites are designed, built and operate in orbit by students, researchers and professors of GAUSS (Group of Astrodynamics of University “La Sapienza”) at School of Aerospace Engineering. In the framework of this program four satellite have already been launched (2 years apart one from the other, starting in 2000) by the Baykonour Cosmodrome and a fifth satellite is scheduled to be launched in the 2008.
The thruster simulation has been performed through three codes combined together. A global code simulating the plasma source and a one dimensional PIC (PPDL) code simulating the plasma exhaust through the magnetic nozzle. Finally a 2-D PIC code has been applied to analyze plasma detachment. These two codes have been combined through a genetic optimization algorithms in order to identify the best thruster configuration defined as a trade-off among performances , total mass and total volume
Explicit analytical equations for single port hybrid rocket combustion chamber sizing
No full textHybrid rockets have several advantages with respect to current propulsion systems like simplicity, safety, reliability, environmental friendliness, and lower cost. To size the combustion chamber, it is fundamental to understand how the length, the external diameter, the volume loading, and the length-to-diameter ratio vary with the design parameters like scale, burning time, average mixture ratio, initial oxidizer flux, and propellant combination. The equations available in the literature are not in explicit form with respect to the aforementioned design parameters, and sometimes they can be misinterpreted by hybrid rocket engineers. Moreover, it is not possible to determine the instantaneous and average characteristic velocities during the burn without a numerical time integration. To show explicitly the real trends, a set of analytical equations has been developed. The key step is the definition of the relation between initial and average mixture ratio and the asymptotic treatment with respect to the ratio between the external and internal diameters. Moreover, an approximate explicit semi-analytical expression of the instantaneous and average characteristic velocities is provided. The explicit analytical equations are validated with the exact implicit solutions showing good agreement and exact asymptotic behavior
Investigation of the influence of gas phase molecular mass variations on hybrid rocket regression rate
No full textMortality risk in a cohort of subjects reported by authorities for cannabis possession for personal use. Results of a longitudinal study.
No full textOBJECTIVE: to study mortality risk in a cohort of cannabis consumers.
DESIGN: longitudinal study on a cohort of 2,511 subjects reported to the Drug Addiction Control Force (DACF) for cannabis possession for personal use between 1990 and 2004 residents in the metropolitan area of Bologna.
METHODS: to identify people already treated for drug dependence, the cohort was linked with the clinical archive of the public treatment centers for drug addiction (PTC) in the metropolitan area of Bologna and the results were separated into PTC clients (subjects in treatment at a PTC, all heroin users) and non-PTC clients (subjects not in treatment at a PTC, no knowledge regarding other illicit drugs being used besides cannabis).
RESULTS: an excess of mortality was observed for all causes in the cohort compared to the general population, both among PTC clients (SMR 14.61 CI 95% 9.21-23.19) and non-clients (SMR 2.43 CI 95% 1.67-3.55). Among PTC clients the highest and most statistically significant SMRs were for overdose, suicide, and AIDS. Among non PTC clients there was an excess for traffic accidents and overdose.
CONCLUSION: the results of the study show an elevated risk of death for consumers of cannabis, a percentage of which probably also consumed other substances, and a very few which presented themselves for treatment at a public drug treatment
center
Emergency Department Presentation and Mortality Rate Due to Overdose: A Retrospective Cohort Study on Non-Fatal Overdoses.
No full textBACKGROUND: The aims of this retrospective cohort study are to describe the presentation characteristics for nonfatal overdose-related complaints at the
emergency departments (EDs) of the metropolitan area of Bologna (northern Italy), to estimate the subsequent risk of mortality by overdose, and to identify the
profiles of the subjects most at risk. METHODS: Records of patients admitted to 10 EDs for overdose between January 2004 and December 2012 were retrospectively evaluated. The International Classification of Diseases was used to ascertain the cause of death. RESULTS: A total of 294 episodes of overdose involving 218 individuals were identified. The total time at risk was 1048 person-years (PY). The mortality rate for all causes was 35.48 per 1000 PY for males and 20.61 per 1000 PY for females. The mortality rate for overdose was 16.6 per 1000 PY for males and 13.74 per 1000 PY for females. In the multivariate regression analysis, the time from first ED overdose access (less than 1 year risk ratio [RR]: 7.07, 95% confidence interval [CI]: 5.32-9.39) was significantly associated with death by overdose. Males, subjects aged >30 years at presentation, patients who refused ED treatment, and those having previously contacted mental health services showed an increased mortality risk due to overdose. CONCLUSIONS: Experiencing a nonfatal overdose within the past 12 months increases the risk of mortality compared with an overdose more than 12 months earlier. Nonfatal overdose patients presenting to an ED form a specific target for prevention projects
ANALYSIS OF DIFFERENT NUMERICAL APPROACHES FOR THE SIMULATION OF A HELICON PLASMA THRUSTER
No full textFeasibility study of mini RF-helicon-double-layer plasma thruster for microsatellite propulsion
No full textThis paper presents a feasibility study conducted to evaluate the possibility of applying an helicon-double-layer plasma-thruster on UNISAT-class micro-satellite. UNISAT satellites are designed, built and operate in orbit by students, researchers and professors of GAUSS. In the framework of this program four satellite have already been launched (2 years apart one from the other, starting in 2000) by the Baykonour Cosmodrome and a fifth satellite is scheduled to be launched in the 2008. Helicon double layer thruster is an innovative type of plasma thruster firstly proposed by Australian National University (ANU) based on helicon plasma source and Double-layer effect.The paper firstly presents the analysis conducted at GAUSS (Group of Astrodynamics of University "La Sapienza"of Rome ) on UNISAT in order to evaluate the available mass budget, volume budget and power budget. Moreover, the minimum required thruster-performances which can be measured using the available instrumentation onboard UNISAT have been assessed. The main requirements of the propulsion system are: thrust 1mN, specific impulse higher than 1000 s, weight lower than 2kg, volume lower than 1 dm3. Then the thruster has been designed firstly applying a global-model of the helicon source and 1-D PIC code operated by a genetic algorithms in order to identify the best optimum thruster configuration ( respect to system requirements, constrains and performances) and finally using a 2-D PIC code in order to verify and refine thruster performances. Copyright 2007 by the IAF or the IAA. All rights reserved
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