University of South Australia

About: University of South Australia is a education organization based out in Adelaide, South Australia, Australia. It is known for research contribution in the topics: Population & Context (language use). The organization has 10086 authors who have published 32587 publications receiving 913683 citations. The organization is also known as: The University of South Australia & UniSA.

A systematic review of the validity and reliability of sedentary behaviour measures used with children and adolescents

Abstract: The aim of this review was to evaluate the reliability and validity of methods used to assess the multiple components of sedentary behaviour (i.e. screen time, sitting, not moving and existing at low energy expenditure) in children and adolescents. Twenty-six studies met our inclusion criteria and were reviewed. Thirteen studies reported the reliability of self- and proxy-report measures of sedentary behaviour and seven of these were found to have acceptable test-retest reliability. Evidence for the criterion validity of self- and proxy-report measures was examined in three studies with mixed results. Seven studies examined the reliability and/or validity of direct observation and the findings were generally positive. Five studies demonstrated the utility of accelerometers to accurately classify sedentary behaviour. Self-report measures provide reliable estimates of screen time, yet their validity remains largely untested. While accelerometers can accurately classify participants' behaviour as sedentary, they do not provide information about type of sedentary behaviour or context. Studies utilizing measures of sedentary behaviour need to more adequately report on the validity and reliability of the measures used. We recommend the use of objective measures of sedentary behaviour such as accelerometers, in conjunction with subjective measures (e.g. self-report), to assess type and context of behaviour.

From Cloud to Fog Computing: A Review and a Conceptual Live VM Migration Framework

Abstract: Fog computing, an extension of cloud computing services to the edge of the network to decrease latency and network congestion, is a relatively recent research trend. Although both cloud and fog offer similar resources and services, the latter is characterized by low latency with a wider spread and geographically distributed nodes to support mobility and real-time interaction. In this paper, we describe the fog computing architecture and review its different services and applications. We then discuss security and privacy issues in fog computing, focusing on service and resource availability. Virtualization is a vital technology in both fog and cloud computing that enables virtual machines (VMs) to coexist in a physical server (host) to share resources. These VMs could be subject to malicious attacks or the physical server hosting it could experience system failure, both of which result in unavailability of services and resources. Therefore, a conceptual smart pre-copy live migration approach is presented for VM migration. Using this approach, we can estimate the downtime after each iteration to determine whether to proceed to the stop-and-copy stage during a system failure or an attack on a fog computing node. This will minimize both the downtime and the migration time to guarantee resource and service availability to the end users of fog computing. Last, future research directions are outlined.

Acute resveratrol supplementation improves flow-mediated dilatation in overweight/obese individuals with mildly elevated blood pressure.

Abstract: Background and Aims: Flow-mediated dilatation of the brachial artery (FMD) is a biomarker of endothelial function and cardiovascular health. Impaired FMD is associated with several cardiovascular risk factors including hypertension and obesity. Various food ingredients such as polyphenols have been shown to improve FMD. We investigated whether consuming re- sveratrol, a polyphenol found in red wine, can enhance FMD acutely and whether there is a dose-response relationship for this effect. Methods and Results: 19 overweight/obese (BMI 25e35 kg m � 2 ) men or post-menopausal women with untreated borderline hypertension (systolic BP: 130e160 mmHg or diastolic BP: 85e100 mmHg) consumed three doses of resveratrol (resVida� 30, 90 and 270 mg) and a placebo at weekly intervals in a double-blind, randomized crossover comparison. One hour after consumption of the supplement, plasma resveratrol and FMD were measured. Data were analyzed by linear regression versus log10 dose of resveratrol. 14 men and 5 women (age 55 � 2 years, BMI 28.7 � 0.5 kg m � 2 ,B P 141� 2/89 � 1 mmHg) completed this study. There was a significant dose effect of resveratrol on plasma resveratrol concentration (P < 0.001) and on FMD (P < 0.01), which increased from 4.1 � 0.8% (placebo) to 7.7 � 1.5% after 270 mg resveratrol. FMD was also linearly related to log10 plasma resveratrol concentration (P < 0.01).

DVB-T Passive Radar Signal Processing

Abstract: This paper provides a detailed overview of the Digital Video Broadcasting Terrestrial (DVB-T) signal structure and the implications for passive radar systems that use these signals as illuminators of opportunity. In particular, we analyze the ambiguity function and explain its delay and Doppler properties in terms of the underlying structure of the DVB-T signal. Of particular concern for radar range-Doppler processing are ambiguities consistent in range and Doppler with targets of interest. In this paper we adopt a mismatched filtering approach for range-Doppler processing. We also recognize that while the structure of the DVB-T signal introduces ambiguities, the structure can also be exploited to better estimate the transmitted signal and channel, as well as any mismatch between transmitter and receiver (e.g., clock offsets). This study presents a scheme for pre-processing both the reference and surveillance signals obtained by the passive radar to mitigate the effects of the ambiguities and the clutter in range-Doppler processing. The effectiveness of our proposed scheme in enhancing target detection is demonstrated using real-world data from an (Australian) 8k-mode DVB-T system. A 29 dB reduction in residual ambiguity levels over existing techniques is observed, and a 36 dB reduction over standard matched filtering; with only a 1 dB reduction in the zero-delay, zero-Doppler peak.

Surface and Capillary Forces Affecting Air Bubble−Particle Interactions in Aqueous Electrolyte

Abstract: The interaction between hydrophilic silica particles and air bubbles in aqueous electrolyte has been studied by colloid probe atomic force microscopy. The interaction was found to be monotonically repulsive on approach. The silica surface was also hydrophobized by dehydroxylation and by treatment with octadecyltrichlorosilane (OTS). In these cases a repulsion was observed at long range with an attraction evident as the bubble−particle separation decreased. For a freshly prepared OTS−silica surface the intervening thin film rapidly collapsed, resulting in particle engulfment or establishment of a three-phase line. For an aged OTS−silica surface a stable film was formed which could be ruptured as the loading force was increased. In all cases adhesion resisted bubble−particle separation. This behavior was rationalized in terms of either attractive surface forces or capillary forces and contact angle hysteresis operating after formation of a three-phase line (TPL).