Control of GaAs nanowire morphology and crystal structure.

The morphology and crystal structure of Au-seeded GaAs nanowires (NWs) grown by molecular beam epitaxy were investigated as a function of the temperature, V/III flux ratio, and Ga flux. Low and intermediate growth temperatures of 400 and 500 °C resulted in a strongly tapered morphology, with stacking faults occurring at an average rate of 0.1 nm(-1). NWs with uniform diameter and the occurrence of crystal defects reduced by more than an order of magnitude were achieved at 600 °C, a V/III flux ratio of 2.3, and a Ga impingement rate on the surface of 0.07 nm s(-1). Comparison of nanowire densities on the various post-growth surfaces suggests a possible incubation time between the moment the Ga shutter is opened and when nanowire growth is initiated. Increasing the flux ratio favored uniform sidewall growth, making the process suitable for the fabrication of core-shell structures.

[The outreach practice with homeless people suffering from severe and chronic mental illness: observations, reality and obstacles.]. / La pratique outreach auprès des personnes itinérantes souffrant de troubles mentaux graves et persistants : observations, réalités et contraintes.

The team working with homeless people has the mandate to favor access to care and social services for all homeless people regardless of age. It has also developed specific outreach services adapted to the reality of homelessness in Montréal. The fundamental principle underlying our practice is universality, be it access or quality of services; all citizens have the right to the same attention from the health system. It's in this perspective that services are offered to homeless people. This article is limited to one aspect of the team's work : the outreach practice with homeless people suffering from severe and chronic mental illness. The authors describe their outreach environment, their clientele and an example of outreach-llustrated with a few cases-as well as the obstacles met. Finally, the authors share their observations and suggestions.

Intensive follow-up does not decrease the risk of repeat suicide attempts.

We carried out a randomized controlled trial to determine whether an intensive intervention after a suicide attempt could decrease by half the risk of a repeat attempt in the following two years. After initial assessment and randomization, experimental subjects attended 18 therapy appointments over one year, including one home visit, and measures to improve attendance. Control subjects received the usual care. Of 63 experimental subjects, 35% made a repeat attempt, and so did 30% of 63 control subjects. The study had a 99% power to detect the desired decrease of risk (30% to 15%). Clearly, the intervention did not achieve its objective.

[Unemployment and the mental health of youth.]. / La santé mentale des jeunes et le chômage.

Unemployment and joblessness are extremely disruptive among youth and the more they continue, the more they may cause deep troubles to the different aspects of the mental health of those same young people. In this article, first the effects of unemployment on the physical health of the young is treated, and the impact of unemployment on the decade of the thirties is compared with that of unemployment in the eighties. Then we look at the reactions to employment, the three stages crossed by adolescents in search of work and the attacks on the mental health of the young, that is : independence, the reaction of worry, the diffusion of identity, self esteem, guilt and shame, anxiety and fear, anger, depression ; the effect on family relations, the disruptions in the organization of free time, the rise in the rate of suicide, the growth in drug and alcohol consumption, and the rise in criminality.