Risk-taking behaviour of Cape Peninsula high-school students. Part I. Introduction and methods

In this study, risk-taking behaviour of Cape Peninsula high-school students was investigated. Suicidal behaviour, cigarette smoking, alcohol consumption, drug use, road-related behaviour, violent behaviour and sexual behaviour were included. This article, the first in a series, describes the rationale and methodology of the project. Sixteen schools were selected so as to yield a representative sample of schools in the three major education departments in the Cape Peninsula (administered by the Department of Education and Training and the Houses of Assembly and Representatives). The final sample size was 7 340 school students. A self-administered questionnaire was completed in a normal school period. Estimates for each education department were weighted to produce an overall estimate. The results are presented by standard and home language(s), and gender. Limitations of the study include its cross-sectional nature; the possibility of under- and over-reporting; the exclusion of important groups of adolescents such as absentees and dropouts, and those attending specialised and private schools; and not being able to present the results separately for each education department

Risk-taking behaviour of Cape Peninsula high-school students. Part VII. Violent behaviour

The prevalence of a wide range of risk-taking behaviour among high-school students in the Cape Peninsula, South Africa, was investigated. In this article, the results for violent behaviour are presented. Cluster sampling techniques produced a sample of 7 340 students from 16 schools in three major education departments. A self-administered questionnaire was completed in a normal school period. Estmates for each education department were weighted to produce an overall estimate. Of the total sample, 12,7%, 9,6% and 13,8% reported that they had been physically injured by another person at school, at home and in other settings, respectively; 11,0% had injured another person during the previous year; 5% had committed an act of vandalism and 9,8% of males and 1,3% of females had carried knives at school. Other trends according to gender, school standard, and home language were identified. Males were more likely to be the perpetrators and victims of violent behaviour; for both genders the extent of victimisation decreased with increasing standard; and fewer Xhosa-speaking students than students in other language groups perpetrated incidents of violent behaviour. The potential for intervention programmes is assessed in a context where much violence is detertnined by sociopolitical factors

Risk-taking behaviour of Cape Peninsula high-school students. Part V. Drug use

The prevalence of a wide range of risk-taking behaviour among high-school students in the Cape Peninsula, South Africa, was investigated. In this article, the results for drug use are presented. Cluster sampling techniques produced a sample of 7 340 students from 16 schools in the three major education departments. A self-administered questionnaire was completed in a normal school period. Estimates for each education departnlent were weighted to produce an overall estimate. Cannabis was the illicit drug most widely used; 7,5% had smoked cannabis, and 2,4% had done so in the previous 7 days. A small subgroup (1,6%) of students had smoked cannabis and methaqualone (Mandrax) together. Reported lifetime use of injectable drugs was 0,5%, and 10,9% had sniffed solvents, 2,6% having done so in the previous 7 days. There were different trends according to gender, standard, and language(s) spoken at home. Of particular note was the Small proportion of Xhosa-speaking females who were involved with drug use. The results suggest that the majority of drug use among school students is experimental. A small number of adolescents abuse drugs and are at risk for its associated problems; intervention is indicated for this group

Risk-taking behaviour of Cape Peninsula high-school students. Part IV. Alcohol use

The prevalence of a wide range of risk-taking behaviour among high-school students in the Cape Peninsula, South Africa, was investigated. In this article, the results for alcohol use are presented. Cluster sampling techniques produced a sample of 7 340 students from 16 schools in the three major education departments. A self-administered questionnaire was completed in a normal school period. Estimates for each education department were weighted to produce an overall estimate. Of the sample, 53,2% reported ever using alcohol; 26,2% had used it recently and 15,4% reported episodes of binge drinking in the previous 14 days. Drinking patterns varied according to school standard, home language, and gender. Males reported higher rates of alcohol use and for both genders rates increased with age. Overall, the prevalence of drinking was highest among adolescents whose home language was English. The proportion of Xhosa-speaking females who drank was very low.The prevalence of binge drinking in particular was identified as being of concern. The findings indicate a need for preventive action and further local research in this area

Risk-taking behaviour of Cape Peninsula high-school students. Part II. Suicidal behaviour

The prevalence of a wide range of risk-taking behaviour among high-school students in the Cape Peninsula, South Africa, was investigated. In this article, the results for suicidal behaviour are presented. Cluster sampling techniques produced a sample of 7 340 students from 16 schools in the three major education departments. A self-administered questionnaire was completed in a normal school period. Estimates for each education department were weighted to produce an overall estimate. During the previous 12 months, 19% of students had seriously thought about harming themselves in a way that might result in their death, 12,4% had told someone that they intended to put an end to their life, and 7,8% had actually tried to put an end to their life. There were different trends according to gender, standard and language(s) spoken at home. Of those who had made a suicide attempt during the previous 12 months, 85,7% indicated that they had seriously thought about doing so, while 57,7% had told someone that they intended putting an end to their life. There is in many cases no continuity from suicidal ideation to communicating suicidal intent to an actual attempt

Risk-taking behaviour of Cape Peninsula high-school students. Part III. Cigarette smoking

The prevalence of a wide range of risk-taking behaviour among high-school students in the Cape Peninsula, South Africa, was investigated. In this article, the results for cigarette smoking are presented. Cluster sam.pling techniques produced a sample of 7 340 students from 16 schools in the three major education departments. A selfadministered questionnaire was completed in a normal school period. Estimates for each education department were weighted to produce an overall estimate. Of the students 18,1% indicated that they smoked at least 1 cigarette per day. Of these, 66,9% had tried to stop. Of those who did not smoke at least 1 cigarette per day, 41,2% had smoked previously and 3,6% intended to start smoking. There were different trends according to gender, standard, and language(s) spoken at home. Of note was the small percentage of Xhosa speaking females who smoked. There is an urgent need for smoking prevention programmes in schools

Risk-taking behaviour of Cape Peninsula high-school students. Part VI. Road-related behaviour

The prevalence of a wide range of risk-taking behaviour among high-school students in the Cape Peninsula, South Africa, was investigated. In this article, the findings for road-related behaviour are presented. Cluster sampling techniques produced a sample of 7 340 students from 16 schools in the three major education departments. A self-administered questionnaire was completed in a normal school period. Estimates for each education department were weighted to produce an overall estimate. During the previous year, 8,5% of the students had been involved in a motor vehicle accident, and 7,4% had been injured in a pedestrian accident. Of those who had driven a vehicle, 63,2% reported driving without a licence; 16,1% drove an overcrowded vehicle; and 8% reported driving under the influence of alcohol or cannabis. Of those who had been on a motorcycle, 47,9% reported riding without a helmet. Despite the availability of seat belts, 37,3% had failed to wear one on the last occasion they were in the front seat of a vehicle. Variations according to gender, standard, and home language(s) were identified. The prevalence of risk behaviour was higher in males, who also showed a more pronounced increase in such behaviour with age. The need for accident prevention programmes remains urgent

Sputter deposition and characterization of lithium cobalt oxide thin films and their applications in thin-film rechargeable lithium batteries

Li Co oxide thin films were deposited by rf magnetron sputtering of a LiCoO{sub 2} target in a 3:1 Ar/O{sub 2} mixture gas. From proton-induced gamma-ray emission analysis and Rutherford backscattering spectrometry, the average composition of these films was determined to be Li{sub 1.15}CoO{sub 2.16}. X-ray powder diffraction patterns of films annealed in air at 500-700 C were consistent with regular rhombohedral structure of crystalline LiCoO{sub 2}. Discharge curves of thin film lithium cells with amoprohous LiCoO{sub 2} showed no obvious structural transition between 4.2 and 1.5 V. Shape of discharge curves of cells with polycrystalline cathodes were consistent with a two-phase voltage plateau at {similar_to}3.9 V with a relatively large capacity and two additional smaller plateaus at higher voltages. Cells with the 700 C annealed cathodes showed a capacity loss of {similar_to} after 1000 cycles between 4.2 and 3.0 V

Interstellar MHD Turbulence and Star Formation

This chapter reviews the nature of turbulence in the Galactic interstellar medium (ISM) and its connections to the star formation (SF) process. The ISM is turbulent, magnetized, self-gravitating, and is subject to heating and cooling processes that control its thermodynamic behavior. The turbulence in the warm and hot ionized components of the ISM appears to be trans- or subsonic, and thus to behave nearly incompressibly. However, the neutral warm and cold components are highly compressible, as a consequence of both thermal instability in the atomic gas and of moderately-to-strongly supersonic motions in the roughly isothermal cold atomic and molecular components. Within this context, we discuss: i) the production and statistical distribution of turbulent density fluctuations in both isothermal and polytropic media; ii) the nature of the clumps produced by thermal instability, noting that, contrary to classical ideas, they in general accrete mass from their environment; iii) the density-magnetic field correlation (or lack thereof) in turbulent density fluctuations, as a consequence of the superposition of the different wave modes in the turbulent flow; iv) the evolution of the mass-to-magnetic flux ratio (MFR) in density fluctuations as they are built up by dynamic compressions; v) the formation of cold, dense clouds aided by thermal instability; vi) the expectation that star-forming molecular clouds are likely to be undergoing global gravitational contraction, rather than being near equilibrium, and vii) the regulation of the star formation rate (SFR) in such gravitationally contracting clouds by stellar feedback which, rather than keeping the clouds from collapsing, evaporates and diperses them while they collapse.Comment: 43 pages. Invited chapter for the book "Magnetic Fields in Diffuse Media", edited by Elisabete de Gouveia dal Pino and Alex Lazarian. Revised as per referee's recommendation

Sub-femto-g free fall for space-based gravitational wave observatories: LISA pathfinder results

We report the first results of the LISA Pathfinder in-flight experiment. The results demonstrate that two free-falling reference test masses, such as those needed for a space-based gravitational wave observatory like LISA, can be put in free fall with a relative acceleration noise with a square root of the power spectral density of 5.2 ± 0.1 fm s−2/√Hz or (0.54 ± 0.01) × 10−15 g/√Hz, with g the standard gravity, for frequencies between 0.7 and 20 mHz. This value is lower than the LISA Pathfinder requirement by more than a factor 5 and within a factor 1.25 of the requirement for the LISA mission, and is compatible with Brownian noise from viscous damping due to the residual gas surrounding the test masses. Above 60 mHz the acceleration noise is dominated by interferometer displacement readout noise at a level of (34.8 ± 0.3) fm/√Hz, about 2 orders of magnitude better than requirements. At f ≤ 0.5 mHz we observe a low-frequency tail that stays below 12 fm s−2/√Hz down to 0.1 mHz. This performance would allow for a space-based gravitational wave observatory with a sensitivity close to what was originally foreseen for LISA