Full stress tensor measurement using colour centres in diamond

Stress and strain are important factors in determining the mechanical, electronic, and optical properties of materials, relating to each other by the material's elasticity or stiffness. Both are represented by second rank field tensors with, in general, six independent components. Measurements of these quantities are usually achieved by measuring a property that depends on the translational symmetry and periodicity of the crystal lattice, such as optical phonon energies using Raman spectroscopy, the electronic band gap using cathodoluminescence, photoelasticity via the optical birefringence, or Electron Back Scattering Diffraction (EBSD). A reciprocal relationship therefore exists between the maximum sensitivity of the measurements and the spatial resolution. Furthermore, of these techniques, only EBSD and off-axis Raman spectroscopy allow measurement of all six components of the stress tensor, but neither is able to provide full 3D maps. Here we demonstrate a method for measuring the full stress tensor in diamond, using the spectral and optical polarization properties of the photoluminescence from individual nitrogen vacancy (NV) colour centres. We demonstrate a sensitivity of order 10 MPa, limited by local fluctuations in the stress in the sample, and corresponding to a strain of about 10^-5, comparable with the best sensitivity provided by other techniques. By using the colour centres as built-in local sensors, the technique overcomes the reciprocal relationship between spatial resolution and sensitivity and offers the potential for measuring strains as small as 10^-9 at spatial resolution of order 10 nm. Furthermore it provides a straightforward route to volumetric stress mapping. Aside from its value in understanding strain distributions in diamond, this new approach to stress and strain measurement could be adapted for use in micro or nanoscale sensors.Comment: 12 pages, 5 figures - supplementary informations included in appendi

Optical properties of a single-colour centre in diamond with a green zero-phonon line

We report the photoluminescence characteristics of a colour centre in diamond grown by plasma-assisted chemical vapour deposition. The colour centre emits with a sharp zero-phonon line at 2.330 eV (λ=532 nm) and a lifetime of 3.3 ns, thus offering potential for a high-speed single-photon source with green emission. It displays a vibronic emission spectrum with a Huang–Rhys parameter of 2.48 at 77 K. Hanbury–Brown and Twiss measurements reveal that the electronic level structure of the defect includes a metastable state that can be populated from the optically excited state

Molecular brakes regulating mTORC1 activation in skeletal muscle following synergist ablation

The goal of the current work was to profile positive (mTORC1 activation, autocrine/paracrine growth factors) and negative [AMPK, unfolded protein response (UPR)] pathways that might regulate overload-induced mTORC1 (mTOR complex 1) activation with the hypothesis that a number of negative regulators of mTORC1 will be engaged during a supraphysiological model of hypertrophy. To achieve this, mTORC1- IRS-1/2 signaling, BiP/CHOP/IRE1, and AMPK activation were determined in rat plantaris muscle following synergist ablation (SA). SA resulted in significant increases in muscle mass of 4% per day throughout the 21 days of the experiment. The expression of the insulin-like growth factors (IGF) were high throughout the 21st day of overload. However, IGF signaling was limited, since IRS-1 and -2 were undetectable in the overloaded muscle from day 3 to day 9. The decreases in IRS-1/2 protein were paralleled by increases in GRB10 Ser501/503 and S6K1 Thr389 phosphorylation, two mTORC1 targets that can destabilize IRS proteins. PKB Ser473 phosphorylation was higher from 3– 6 days, and this was associated with increased TSC2 Thr939 phosphorylation. The phosphorylation of TSC2 Thr1345 (an AMPK site) was also elevated, whereas phosphorylation at the other PKB site, Thr1462, was unchanged at 6 days. In agreement with the phosphorylation of Thr1345, SA led to activation of AMPK1 during the initial growth phase, lasting the first 9 days before returning to baseline by day 12. The UPR markers CHOP and BiP were elevated over the first 12 days following ablation, whereas IRE1 levels decreased. These data suggest that during supraphysiological muscle loading at least three potential molecular brakes engage to downregulate mTORC1. m

Evaluation of a Density-Based Rapid Diagnostic Test for Sickle Cell Disease in a Clinical Setting in Zambia

Although simple and low-cost interventions for sickle cell disease (SCD) exist in many developing countries, child mortality associated with SCD remains high, in part, because of the lack of access to diagnostic tests for SCD. A density-based test using aqueous multiphase systems (SCD-AMPS) is a candidate for a low-cost, point-of-care diagnostic for SCD. In this paper, the field evaluation of SCD-AMPS in a large (n = 505) case-control study in Zambia is described. Of the two variations of the SCD-AMPS used, the best system (SCD-AMPS-2) demonstrated a sensitivity of 86% (82–90%) and a specificity of 60% (53–67%). Subsequent analysis identified potential sources of false positives that include clotting, variation between batches of SCD-AMPS, and shipping conditions. Importantly, SCD-AMPS-2 was 84% (62–94%) sensitive in detecting SCD in children between 6 months and 1 year old. In addition to an evaluation of performance, an assessment of end-user operability was done with health workers in rural clinics in Zambia. These health workers rated the SCD-AMPS tests to be as simple to use as lateral flow tests for malaria and HIV

Faculty members engaging in transformative PETE: a feminist perspective

The purpose of this study was to describe sport pedagogy faculty members’ (FMs) efforts at engaging in transformative physical education teacher education (T-PETE). T-PETE stresses the importance of FMs creating social change through their pedagogical approach and begins by asking preservice teachers (PTs) to reflect on their perspectives and practices (Tinning, 2017 Tinning, R. (2017). Transformative pedagogies and physical education. In C. Ennis (Ed.), The Routledge handbook of physical education pedagogies (pp. 295–306). New York: Taylor & Francis. [Google Scholar]. Transformative pedagogies and physical education. In C. Ennis (Ed.), The Routledge handbook of physical education pedagogies (pp. 295–306). New York: Taylor & Francis; Ukpokodu, 2009. The practice of transformative pedagogy. Journal on Excellence in College Teaching, 20(2), 43–67.). Participants were three white, female, able-bodied, lesbian/gay sport pedagogy FMs. The study was conducted in the United States. Feminist theory and feminist pedagogy drove data collection and analysis. Data were collected by employing a series of qualitative methods. An inductive and deductive analysis revealed that FMs had specific T-PETE goals, content, and pedagogies. Furthermore, several factors served to facilitate and limit the FMs’ effectiveness when engaging in T-PETE. The findings suggest that program-wide PETE reform is necessary in the United States for creating social change, and influencing PTs perspectives and practices. In addition, they suggest that American PETE programs might benefit from greater diversity among the FMs who staff them

‘It brings the lads together’: A critical exploration of older men’s experiences of a weight management programme delivered through a Healthy Stadia project

Older men whose weight is considered unhealthy may experience particular barriers that can restrict their adoption of health improvement interventions. Despite promising findings recommending the use of sports settings to facilitate health promotion with men, little evidence has addressed older men’s health needs for, or experiences of, these settings. Using a qualitative methodology, this study explored the experiences of 14 ageing men attending a football-led weight management programme delivered at a community sports setting. The thematic analysis of semi-structured interviews elucidates important insights regarding the provision of sports-led health improvement interventions for this population. Men especially valued the opportunity to play sports and do physical activity in an environment that promotes ‘inclusive’ competition and caring interpersonal relationships. Implicit in the findings is the key role of practitioners in promoting social engagement. We conclude the paper with key practical implications of this research

Observational study on variability between biobanks in the estimation of DNA concentration.

BACKGROUND: There is little confidence in the consistency of estimation of DNA concentrations when samples move between laboratories. Evidence on this consistency is largely anecdotal. Therefore there is a need first to measure this consistency among different laboratories and then identify and implement remedies. A pilot experiment to test logistics and provide initial data on consistency was therefore conceived. METHODS: DNA aliquots at nominal concentrations between 10 and 300 ng/mul were dispensed into the wells of 96-well plates by one participant - the coordinating centre. Participants estimated the concentration in each well and returned estimates to the coordinating centre. RESULTS: Considerable overall variability was observed among estimates. There were statistically significant differences between participants' measurements and between fluorescence emission and absorption spectroscopy. CONCLUSION: Anecdotal evidence of variability in DNA concentration estimation has been substantiated. Reduction in variability between participants will require the identification of major sources of variation, specification of effective remedies and their implementation