On Toroidal Azulenoids and Other Shapes of Fullerene Cage

The possibility of toroidal cages of carbon with repeating five and seven membered ring pairs (azulene units) upon their surfaces is briefly discussed. Some of the difficulties in recognising possible fullerene cage shapes are pointed out.     

The safer choices project: methodological issues in school-based health promotion intervention research

Randomized trials of school-based health promotion programs present unique design and analytical issues not widely discussed in the research literature. This article describes the Safer Choices study--a school-based program for prevention of HIV, other sexually transmitted diseases, and pregnancy--to illustrate critical methodological issues involved in large-scale, school-based intervention trials, particularly those evaluating interventions with a school-wide focus. The issues presented are: 1) comparability of the intervention and control groups even when few units are randomized; 2) factors that affect the decision to use a cohort or cross-sectional design; and 3) appropriate analysis strategy when the unit of randomization and intervention is at the school level, but observations are at the student level.     

Characterization of micromachined silicon rectangular waveguide at 400 GHz

We present the first characterization of a micromachined silicon rectangular waveguide at 400GHz. The silicon waveguide has an average loss of 0.086dB/mm for a range of 350-460GHz. The waveguides are formed using well known microfabrication techniques and demonstrate a successful first step towards the use of silicon waveguides as a viable option for THz systems.     

Laser transfer of sol-gel ferroelectric thin films using an ITO release layer

A new laser transfer process is reported which allows damage-free transfer of ferroelectric thin films from a growth substrate directly to a target substrate. The thin film ferroelectric material is deposited on a fused silica growth substrate with a sacrificial release layer of ITO (indium tin oxide). Regions of the film that are to be transferred are then selectively metallised, and bonded to the target substrate. Separation from the growth substrate is achieved by laser ablation of the ITO release layer by a single pulse from a KrF excimer laser, with the laser light being incident through the growth substrate. The residual ITO on the transferred ferroelectric layer is electrically conducting, and may be suitable for incorporation into the final device, depending on the application. The new process has been demonstrated for 500 nm-thick layers of sol-gel PZT which were thermosonically bonded to a silicon target substrate prior to laser release. The transferred films show ferroelectric behaviour and have a slightly reduced permittivity compared to the as-deposited material.     

Design and fabrication of a 1 m model of the 70 mm bore twinaperture superconducting quadrupole for the LHC insertions

For reasons of geometrical acceptance, 70 mm bore twin aperture quadrupoles are required in the LHC insertions. For an operating gradient of 160 T/m at 4.5 K, a design based on a four layer coil wound from two graded 8.2 mm NbTi conductors has been developed. Three 1 m single aperture quadrupoles of this design have been built and successfully tested. Thereafter, the magnets have been disassembled and the coils re-collared using self-supporting collars. In this paper, we describe the design features of the twin aperture quadrupole, and report on the initial collaring tests and procedures for collaring and final assembly of the 1 m magnet     

Agricultural productivity in the lower Mekong Basin: trends and future prospects for food security

This paper examines the spatial and temporal variability and trends of agricultural productivity in the Lower Mekong River Basin. We also show the future productivity requirements for both food security and the maintenance of the basin’s export potential at the current level for the projected increase in population by 2030. We considered both rice and upland crops grown in the basin and estimated physical and economic productivity in terms of land and population. Both physical and economic productivity of rice in terms of land area and population is highest in Vietnam, moderate in Laos and lowest in Thailand and Cambodia. However, the physical productivity of upland crops such as sugarcane and maize is highest in Thailand. Economic productivity of upland crops is highest in Laos followed by Vietnam, Cambodia and Thailand, respectively and is much higher than that of rice. Total economic productivity is dominated by rice in all countries except Laos. In general, productivity has increased in all four riparian countries between 1993 and 2004 and there appears to be considerable scope for further increases, which will allow maintenance of the current level of rice export in the future, despite population growth.

Ethnic stereotypes: The significance of consensus.

Investigated whether the degree of consensus in trait attribution to ethnic groups has any particular meaning to the individual. Canadian 9th and 12th graders (n = 36) were presented with traits previously found in the stereotypes about different groups, and asked to identify the ethnic group so characterized. 3 independent variables were manipulated: consensus of the attributes, age of the Ss, and the number of attributes presented. Dependent variables included the accuracy and the perceived difficulty of identification. Results indicate that the degree of consensus in the stereotype had considerable information value to the Ss. This suggests that stereotypes generally develop from information available to a community, and that the consensus noted in stereotype assessment procedures reflects the consistency of this information. (French summary) (16 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)