Experimental and theoretical investigations of a supercavitating hydrofoil

An experimental investigation of the two-dimensional hydrodynamic characteristics of a thin, supercavitating hydrofoil is described. The effects of twist and vibration of the thin hydrofoil model are considered, and experimental techniques for investigating spanwise twist and leading edge vibration and data correction methods are described. The theory of Wu for the forces on fully cavitating hydrofoils was used to calculate the forces on this profile. The calculated lift is in good agreement with the experimental results; however, the measured drag differs appreciably from the theoretical values

Wet chemical etching mechanism of silicon

We review what can be said on wet chemical etching of single crystals from the viewpoint of the science of crystal growth. Starting point is that there are smooth and rough crystal surfaces. The kinetics of smooth faces is controlled by a nucleation barrier that is absent on rough faces. The latter therefore etch faster by orders of magnitude. The analysis of the diamond crystal structure reveals that the {111} face is the only smooth face in this lattice-other faces might be smooth only because of surface reconstruction. In this way we explain the minimum of the etch rate in KOH:H2O in the <001> direction. Two critical predictions concerning the shape of the minimum of the etch rate close to <001> and the transition from isotropic to anisotropic etching in HF:HNO3 based solutions are tested experimentally. The results are in-agreement with the theor

Braze alloys for high temperature service

Two groups of refractory metal compositions have been developed that are very useful as high temperature brazing alloys for sealing between ceramic and metal parts. Each group consists of various compositions of three selected refractory metals which, when combined, have characteristics required of good braze alloys

CONTINGENT VALUATION OF RURAL TOURISM DEVELOPMENT WITH TESTS OF SCOPE AND MODE STABILITY

Contingent valuation is used to measure the social impacts of tourism in rural Oregon communities. Impacts are substantial, for example, annual household willingness to pay (WTP) to reduce traffic congestion is $186. Study features include tests of sensitivity to a change in scope, tests of stability across survey mode, and a thorough system of “no” –vote follow-up questions in a referendum format. While there is no evidence of scope effects (at the 0.05 level), results indicate that conclusions regarding sensitivity to scope may be dependent on the test used. WTP estimates are substantially less with the mail versus telephone survey mode.Community/Rural/Urban Development,

High temperature ceramic interface study

Monolithic SiC and Si3N4 are susceptible to contact stress damage at static and sliding interfaces. Transformation-toughened zirconia (TTZ) was evaluated under sliding contact conditions to determine if the higher material fracture toughness would reduce the susceptibility to contact stress damage. Contact stress tests were conducted on four commercially available TTZ materials at normal loads ranging from 0.455 to 22.7 kg (1 to 50 pounds) at temperatures ranging from room temperature to 1204C (2200 F). Static and dynamic friction were measured as a function of temperature. Flexural strength measurements after these tests determined that the contact stress exposure did not reduce the strength of TTZ at contact loads of 0.455, 4.55, and 11.3 kg (1, 10, and 25 pounds). Prior testing with the lower toughness SiC and Si3N4 materials resulted in a substantial strength reduction at loads of only 4.55 and 11.3 kg (10 and 25 pounds). An increase in material toughness appears to improve ceramic material resistance to contact stress damage. Baseline material flexure strength was established and the stress rupture capability of TTZ was evaluated. Stress rupture tests determined that TTZ materials are susceptible to deformation due to creep and that aging of TTZ materials at elevated temperatures results in a reduction of material strength

Robust autoresonant excitation in the plasma beat-wave accelerator: a theoretical study

A modified version of the Plasma Beat-Wave Accelerator scheme is introduced and analyzed, which is based on autoresonant phase-locking of the nonlinear Langmuir wave to the slowly chirped beat frequency of the driving lasers via adiabatic passage through resonance. This new scheme is designed to overcome some of the well-known limitations of previous approaches, namely relativistic detuning and nonlinear modulation or other non-uniformity or non-stationarity in the driven Langmuir wave amplitude, and sensitivity to frequency mismatch due to measurement uncertainties and density fluctuations and inhomogeneities

DNA Vaccines Encoding Antigen Targeted to MHC Class II Induce Influenza-Specific CD8+ T Cell Responses, Enabling Faster Resolution of Influenza Disease

Current influenza vaccines are effective but imperfect, failing to cover against emerging strains of virus and requiring seasonal administration to protect against new strains. A key step to improving influenza vaccines is to improve our understanding of vaccine induced protection. Whilst it is clear that antibodies play a protective role, vaccine induced CD8+ T cells can improve protection. To further explore the role of CD8+ T cells we used a DNA vaccine that encodes antigen dimerised to an immune cell targeting module. Immunising CB6F1 mice with the DNA vaccine in a heterologous prime boost regime with the seasonal protein vaccine improved the resolution of influenza disease compared to protein alone. This improved disease resolution was dependent on CD8+ T cells. However, DNA vaccine regimes that induced CD8+ T cells alone were not protective and did not boost the protection provided by protein. The MHC targeting module used was an anti-I-Ed single chain antibody specific to the BALB/c strain of mice. To test the role of MHC targeting we compared the response between BALB/c, C57BL/6 mice and an F1 cross of the two strains (CB6F1). BALB/c mice were protected, C57BL/6 were not and the F1 had an intermediate phenotype; showing that the targeting of antigen is important in the response. Based on these findings, and in agreement with other studies using different vaccines, we conclude that in addition to antibody, inducing a protective CD8 response is important in future influenza vaccines

Problems, policy and politics – perspectives of public health leaders on food insecurity and human rights in Australia

Background: To achieve zero hunger targets set within the United Nations’ Agenda 2030, high-income countries such as Australia must reconsider current efforts to improve food security. This study aimed to; explore perspectives from public health nutrition experts on the usefulness of drawing on the international human right to food, and associated mechanisms, to address food insecurity; identify potential roles of key stakeholders in Australia to implement a rights-based approach; and examine barriers and enablers to achieving the right to food in Australia. Methods: Qualitative in-depth interviews were conducted with key informants ( \u3e 10 years professional experience). Braun and Clarke’s (2006) six-phase approach to thematic analysis was employed to analyse data, using Kingdon’s multiple streams framework (1984) to examine interactive variables which affect policy-making processes. Results: Thirty interviews took place, with most participants representing academia (n = 16), majority had 10–14 years of experience (n = 12) and almost one quarter (n = 7) were in senior leadership roles. Participants believed that framing food insecurity as a human rights issue could be effective when communicating with some audiences, however alternative rhetoric is more popular and potentially more effective. Citizens, government, food industry, non-profit sector, research/tertiary and legal institutions were described as playing critical roles. Barriers to progress were identified as lack of awareness and acknowledgement of the problem, prioritisation of the private sector, lack of political will and domestic laws, and an inefficient/ineffective charitable food sector. Participants identified various enablers and opportunities for implementing a rights-based approach such as grass-roots advocacy efforts to raise awareness of the issue, integrating human rights into government frameworks and community projects and the political will to support action aligned with sustainable development. Conclusions: Human rights language and mechanisms have the potential to trigger genuine commitment to addressing food insecurity however should be used with caution. Australia’s public health workforce requires increased capacity to implement a human-rights approach and framing such efforts to align with sustainable development may achieve greater political action. Trial registration: Ethics approval was received from the Deakin University Human Research Ethics committee (project ID HEAG 168_2018)