Young children’s physical activity levels in primary (elementary) schools: what impact does physical education lessons have for young children?

Objectives: This paper explores the impact of physical education (PE) lessons, focusing on children aged 6–7 years, an underrepresented age in physical activity research. Methods: 10 children wore Actigraph accelerometers recording physical activity throughout the school day (9 am until 3.10 pm), for a year. Repeated measures ANOVA analysed: type of day (days including PE and days that did not) and gender (p <.05). Results: Boys achieved 88% (girls 70%) of the recommended daily physical activity levels on PE days compared to 77% (girls 63%) on non PE days. Significant differences occurred, boys more active than girls also PE days being more active than non-PE days. Conclusion: The novel findings indicate PE lessons significantly contributes to children’s physical activity levels

A precise CNOT gate in the presence of large fabrication induced variations of the exchange interaction strength

We demonstrate how using two-qubit composite rotations a high fidelity controlled-NOT (CNOT) gate can be constructed, even when the strength of the interaction between qubits is not accurately known. We focus on the exchange interaction oscillation in silicon based solid-state architectures with a Heisenberg Hamiltonian. This method easily applies to a general two-qubit Hamiltonian. We show how the robust CNOT gate can achieve a very high fidelity when a single application of the composite rotations is combined with a modest level of Hamiltonian characterisation. Operating the robust CNOT gate in a suitably characterised system means concatenation of the composite pulse is unnecessary, hence reducing operation time, and ensuring the gate operates below the threshold required for fault-tolerant quantum computation.Comment: 9 pages, 8 figure

Electron Exchange Coupling for Single Donor Solid-State Qubits

Inter-valley interference between degenerate conduction band minima has been shown to lead to oscillations in the exchange energy between neighbouring phosphorus donor electron states in silicon \cite{Koiller02,Koiller02A}. These same effects lead to an extreme sensitivity of the exchange energy on the relative orientation of the donor atoms, an issue of crucial importance in the construction silicon-based spin quantum computers. In this article we calculate the donor electron exchange coupling as a function of donor position incorporating the full Bloch structure of the Kohn-Luttinger electron wavefunctions. It is found that due to the rapidly oscillating nature of the terms they produce, the periodic part of the Bloch functions can be safely ignored in the Heitler-London integrals as was done by Koiller et. al. [Phys. Rev. Lett. 88,027903(2002),Phys. Rev. B. 66,115201(2002)], significantly reducing the complexity of calculations. We address issues of fabrication and calculate the expected exchange coupling between neighbouring donors that have been implanted into the silicon substrate using an 15keV ion beam in the so-called 'top down' fabrication scheme for a Kane solid-state quantum computer. In addition we calculate the exchange coupling as a function of the voltage bias on control gates used to manipulate the electron wavefunctions and implement quantum logic operations in the Kane proposal, and find that these gate biases can be used to both increase and decrease the magnitude of the exchange coupling between neighbouring donor electrons. The zero-bias results reconfirm those previously obtained by Koiller.Comment: 10 Pages, 8 Figures. To appear in Physical Review

Killer whale (Orcinus orca) predation on beaked whales (Mesoplodon spp.) in the Bremer Sub-Basin, Western Australia

Observations of killer whales (Orcinus orca) feeding on the remains of beaked whales have been previously documented; however, to date, there has been no published account of killer whales actively preying upon beaked whales. This article describes the first field observations of killer whales interacting with, hunting and preying upon beaked whales (Mesoplodon spp.) on four separate occasions during 2014, 2015 and 2016 in the Bremer Sub-Basin, off the south coast of Western Australia

Far-Infrared Spectroscopy of the Troposphere (FIRST): Flight Performance and Data Processing

The radiative balance of the troposphere, and hence global climate, is dominated by the infrared absorption and emission of water vapor, particularly at far-infrared (far-IR) wavelengths from 15-50 μm. Current and planned satellites observe the infrared region to about 15.4 μm, ignoring spectral measurement of the far-IR region from 15 to 100μm. The far-infrared spectroscopy of the troposphere (FIRST) project, flown in June 2005, provided a balloon-based demonstration of the two key technologies required for a space-based far-IR spectral sensor. We discuss the FIRST Fourier transform spectrometer system (0.6 cm-1 unapodized resolution), its radiometric calibration in the spectral range from 10 to 100 μm, and its performance and science data from the flight. Two primary and two secondary goals are given and data presented to show the goals were achieved by the FIRST flight

Gendered performances in sport: an embodied approach

Despite significant advances in recent years, gender inequalities remain apparent within the context of sport participation and engagement. One of the problems, however, when addressing gender issues in sport is the continued assumption by many sport practitioners that the experiences of women and men will always be different because of perceived physiological characteristics. Adopting a focus based solely upon perceived gendered differences often overlooks the importance of recognising individual experience and the prevailing social influences that impact upon participation, such as age, class, race and ability. An embodied approach, as well as seeking to move beyond mind/body dualisms, incorporates the physiological with the social and psychological. Therefore, it is suggested that while considerations of gender remain important, they need to be interpreted alongside other interconnecting and influential (at varying times and occasions) social and physical factors. It is argued that taking the body as a starting point opens up more possibilities to manoeuvre through the mine field that is gender and sport participation. The appeal of an embodied approach to the study of gender and sport is in its accommodation of a wider multi-disciplinary lens. Particularly, by acknowledging the subjective, corporeal, lived experiences of sport engagement, an embodied approach offers a more flexible starting point to negotiate the theoretical and methodological challenges created by restrictive discourses of difference

Identifying an Experimental Two-State Hamiltonian to Arbitrary Accuracy

Precision control of a quantum system requires accurate determination of the effective system Hamiltonian. We develop a method for estimating the Hamiltonian parameters for some unknown two-state system and providing uncertainty bounds on these parameters. This method requires only one measurement basis and the ability to initialise the system in some arbitrary state which is not an eigenstate of the Hamiltonian in question. The scaling of the uncertainty is studied for large numbers of measurements and found to be proportional to one on the square-root of the number of measurements.Comment: Minor corrections, Accepted for publication in Physical Review

A virtual reality food court to study meal choices in youth: design and assessment of usability

BACKGROUND: Regular consumption of take-out and fast foods with sugary drinks is associated with poor quality diets and higher prevalence of obesity. Among the settings where such food is consumed is the food court typically found in shopping malls prominent in many countries. OBJECTIVE: The objective of this research was to develop a virtual reality food court that could be used to test food environmental interventions, such as taxation, and ultimately to facilitate the selection of healthier food choices. METHODS: Fourteen food courts in Sydney, Australia were selected to include those in the city center and suburbs of high and low socioeconomic status. Researchers visited the courts to collect information on number and type of food outlets, all menu items for sale, cost of foods and beverages and sales promotions. This information was used to assemble 14 food outlets typically found in food courts, and representative menus were compiled. The UNITY gaming platform was used to design a virtual reality food court that could be used with HTC VIVE goggles. Participants navigated the virtual reality food court using the head-mounted display, keyboard, and mouse and selected a lunch meal, including food and beverage. A validated questionnaire on presence within the virtual reality food court and system usability was completed at the end of the session. The constructs for presence included a sense of control, sensory fidelity, realism, distraction, and involvement. Questions were rated on a scale from 1 (worst) through 7 (best) for each of 28 questions giving a maximum total score of 196. The systems usability scale (SUS) that gives a final score out of 100 was also assessed. RESULTS: One hundred and sixty-two participants with a mean age of 22.5 (SD 3.1) years completed the survey. The mean score for total presence was 144 (SE 1.4) consisting of control: 62.1 (SE 0.8), realism: 17.5 (SE 0.2), involvement: 9.6 (SE 0.2), sensory fidelity: 34.9 (SE 0.4), and distraction: 24.0 (SE 0.3). The mean SUS was 69 (SE 1.1). CONCLUSIONS: Virtual reality shows promise as a tool to study food choice for test interventions to inform practice and policy

Identifying a Two-State Hamiltonian in the Presence of Decoherence

Mapping the system evolution of a two-state system allows the determination of the effective system Hamiltonian directly. We show how this can be achieved even if the system is decohering appreciably over the observation time. A method to include various decoherence models is given and the limits of this technique are explored. This technique is applicable both to the problem of calibrating a control Hamiltonian for quantum computing applications and for precision experiments in two-state quantum systems. For simple models of decoherence, this method can be applied even when the decoherence time is comparable to the oscillation period of the system.Comment: 8 pages, 6 figures. Minor corrections, published versio

Farmer and researcher partnerships in Malawi: developing soil fertility technologies for the near-term and far-term

In Malawi, intensive production of maize (Zea mays) is pursued on over 60% of smallholder land, yet application of nutrients is almost nil. To improve adoption of soil productivity-enhancing technologies, two participatory methods were pursued: (i) a novel 'mother-and-baby' trial design and (ii) participatory action research with communities in a southern Malawi watershed. The central 'mother trial' was managed by researchers (replicated within a site) and systematically linked to farmer-managed 'baby' trials to cross-check biological performance with farmer assessment. The watershed approach involved a partnership of researchers and farmers addressing soil management. Technologies tested in both approaches integrated legumes into existing maize-based systems, sometimes in combination with inorganic fertilizers. Across methods, legume intensification increased yields by approximately 40% (net benefit increase of approximately US$50 ha-1) and fertilizer increased yields by approximately 70% compared with continuous maize grain yields of about 1100 kg ha-1. Farmer assessment prioritized technologies that included secondary benefits, such as weed suppression, grain legume yields, and low-labour-demanding fertilizer. A survey indicated that participating researchers and extension staff had reservations about the amount of time required to interact with farmers, and no clear consensus emerged regarding the best approach. There has been wider adoption of the mother-and-baby trial method by scientists in neighbouring countries, indicating the value of systematically incorporating farmers' input