Electron effective mass in Al0.72_{0.72}Ga0.28_{0.28}N alloys determined by mid-infrared optical Hall effect

The effective electron mass parameter in Si-doped Al$_{0.72}$Ga$_{0.28}$N is determined to be $m^\ast=(0.336\pm0.020)\,m_0$ from mid-infrared optical Hall effect measurements. No significant anisotropy of the effective electron mass parameter is found supporting theoretical predictions. Assuming a linear change of the effective electron mass with the Al content in AlGaN alloys and $m^\ast=0.232\,m_0$ for GaN, an average effective electron mass of $m^\ast=0.376\,m_0$ can be extrapolated for AlN. The analysis of mid-infrared spectroscopic ellipsometry measurements further confirms the two phonon mode behavior of the E$_1$(TO) and one phonon mode behavior of the A$_1$(LO) phonon mode in high-Al-content AlGaN alloys as seen in previous Raman scattering studies

An evaluation of a video-based intervention targeting alcohol consumption during aquatic activities

Objective: Alcohol consumption and being male are drowning risk factors. Changing beliefs and intentions to undertake risky aquatic-related behaviours, such as consuming alcohol, is key to reducing loss of life and injury. We evaluated the impact of a video encouraging change in young males’ social cognitions and intentions to discourage their mates as well as their own alcohol consumption around the water. Method: A three-wave non-controlled pre-test-post-test design was adopted. A convenience sample of Australian males aged 18–34 years (N = 97) who self-reported drinking alcohol and engaging in aquatic activities was recruited. Participants were surveyed at baseline (T1) regarding social cognition constructs and intentions, immediately after viewing the video (T2) and at a one-month follow-up (T3). Results: Repeated measures ANOVAs revealed significant main effects of time on intentions, subjective norms, and attitudes regarding discouraging mates from drinking and swimming, but no significant main effects of time on perceived behavioural control or risk perceptions. The same patterns of effects were observed regarding drinking and swimming on males’ own behaviour. Conclusions: The video has the potential to influence young males’ social cognitions regarding their mates’ and their own risky drinking behaviour around water in the short term, although sustained interventions are required. Messaging delivered on-site at popular aquatic locations in the lead-up to traditionally risky periods for alcohol-related drowning should be considered. Provision of strategies to combat social pressures among young males to act on their intentions to engage in drinking and swimming are needed

Messing with nature? Exploring public perceptions of geoengineering in the UK

Anthropogenic influence on the climate – and possible societal responses to it – offers a unique window through which to examine the way people think about and relate to the natural world. This paper reports data from four, one-day deliberative workshops conducted with members of the UK public during early 2012. The workshops focused on geoengineering – the deliberate, large-scale manipulation of the planetary environment – as one of three possible responses to climate change (alongside mitigation and adaptation). Here, we explore one of the most pervasive and wide-ranging themes to emerge from the workshops: whether geoengineering represented an unprecedented human intervention into ‘nature’, and what the moral consequences of this might be. Using the concept of ‘messing with nature’ as an analytical lens, we explore public perceptions of geoengineering. We also reflect on why ‘messing with nature’ was such a focal point for debate and disagreement, and whether the prospect of geoengineering may reveal new dimensions to the way that people think about the natural world, and their relationship to it

Governance traps in climate change politics: re-framing the debate in terms of responsibilities and rights

There is a strong sense of malaise surrounding climate politics today. This has been created at least in part by factors such as the chasm between the scale of action required and the adequacy of current political commitments, stalemate in global negotiations, the low price of carbon, and a growing sense of indifference among the publics of some developed countries about the threat posed by climate change. Within the policy community these issues are generally treated as different problems each to be overcome on their own terms. Yet, we argue, suggested solutions to these problems hold much in common—namely a focus on identifying agency, whether the capacity of institutions to act or the behavior of individuals. What is often missing from such accounts of climate politics is a recognition that the problems of how agency is attributed, what we might term governance traps, are structural in nature. Governing climate change therefore requires that we study the conditions through which these challenges arise and which in turn serve to frame agency in particular ways. We suggest that examining the ways in which notions of responsibilities and rights are currently being framed within climate politics provides one way into these dynamics. This opens up the critical questions that need to be addressed ahead of the critical Conference of the Parties meeting in Paris in November 2015

Interwell relaxation times in p-Si/SiGe asymmetric quantum well structures: the role of interface roughness

We report the direct determination of nonradiative lifetimes in Si∕SiGe asymmetric quantum well structures designed to access spatially indirect (diagonal) interwell transitions between heavy-hole ground states, at photon energies below the optical phonon energy. We show both experimentally and theoretically, using a six-band k∙p model and a time-domain rate equation scheme, that, for the interface quality currently achievable experimentally (with an average step height ⩾1 Å), interface roughness will dominate all other scattering processes up to about 200 K. By comparing our results obtained for two different structures we deduce that in this regime both barrier and well widths play an important role in the determination of the carrier lifetime. Comparison with recently published experimental and theoretical data obtained for mid-infrared GaAs∕AlxGa1−xAs multiple quantum well systems leads us to the conclusion that the dominant role of interface roughness scattering at low temperature is a general feature of a wide range of semiconductor heterostructures not limited to IV-IV material

The role of endotoxin/lipopolysaccharide in surgically induced tumour growth in a murine model of metastatic disease

Surgical removal of a primary tumour is often followed by rapid growth of previously dormant metastases. Endotoxin or lipopolysaccharide, a cell wall constituent of Gram-negative bacteria, is ubiquitously present in air and may be introduced during surgery. BALB/c mice received a tail vein injection of 105 4T1 mouse mammary carcinoma cells. Two weeks later, animals were subjected to surgical trauma or an intraperitoneal injection of endotoxin (10 μg per animal). Five days later, animals which underwent open surgery, laparoscopy with air sufflation or received an endotoxin injection displayed increased lung metastasis compared to anaesthetic controls. These increases in metastatic tumour growth were reflected in increased tumour cell proliferation and decreased apoptosis within lung metastases. Circulating levels of the angiogenic cytokine, vascular endothelial growth factor (VEGF), were also elevated in these groups and correlated with increased plasma levels of endotoxin. Endotoxin treatment for 18 h (>10 ng ml–1) directly up-regulated VEGF production by the 4T1 tumour cells in vitro. Metastatic tumour growth in mice undergoing carbon dioxide laparoscopy, where air is excluded, was similar to anaesthetic controls. These data indicate that endotoxin introduced during surgery is associated with the enhanced growth of metastases following surgical trauma, by altering the critical balances governing cellular growth and angiogenesis. © 1999 Cancer Research Campaig

The characteristics of drowning among different types of international visitors to Australia and how this contributes to their drowning risk

Objective: Australia is a popular destination for international visitors. This study reviews international visitor drowning deaths in Australia and analyses drowning by visitor type. Methods: A total population retrospective study exploring drowning deaths of international visitors was conducted between 2008 and 2018. Data were extracted from the Royal Life Saving National Fatal Drowning Database and categorised into four subgroups: overseas tourists, international students, working holiday makers and work-related visitors. Descriptive statistics, non-parametric tests and relative risk (RR) were calculated. Results: In total, 201 international visitors drowned in Australia, 7% of all drowning deaths; a crude drowning rate of 0.27/100,000 visitors versus 0.95/100,000 for residents (RR=0.19 [95% CI: 0.16–0.22]). Most deaths were males (79%) and people aged 18–34 years (50%). Visitors frequently drowned at beaches (33%), and when swimming (41%). Thirty-five percent recorded a pre-existing medical condition. Overseas tourists on holiday were the most likely to drown compared to other subgroups. Conclusion: International visitors represent a small but increasing proportion of people drowning in Australia. The circumstances of which visitors drown vary by travel purpose, age, country of origin, location of drowning and activity. Implications for public health: International visitors have unique safety needs, requiring tailored prevention based on the purpose of travel and country of origin

Quality Improvement: A guide for services

This guide provides information for clinicians from organisations and services participating in PCOC to use their reports and the suite of PCOC quality improvement tools for continuous improvement, and to demonstrate improvement in patient and family/carer outcomes