Cell-surface receptors and proteins on platelet membranes imaged by scanning force microscopy using immunogold contrast enhancement

High resolution scanning force microscope (SFM) images of fibrinogen-exposed platelet membranes are presented. Using ultrasharp carbon tips, we are able to obtain submolecular scale resolution of membrane surface features. Corroboration of SFM results is achieved using low voltage, high resolution scanning electron microscopy (LVHRSEM) to image the same protein molecule that is seen in the SFM. We obtain accurate height dimensions by SFM complemented by accurate lateral dimensions obtained by LVHRSEM. The use of 14- and 5-nm gold labels to identify specific membrane-bound biomolecules and to provide contrast enhancement with the SFM is explored as a useful adjunct to observation of unlabeled material. It is shown that the labels are useful for locating specific protein molecules on platelet membrane surfaces and for assessing the distribution of these molecules using the SFM. Fourteen nm labels are shown to be visible over the membrane corrugation, whereas 5-nm labels appear difficult to resolve using the present SFM instrumental configuration. When using the 5-nm labels, collateral use of LVHRSEM allows one to examine SFM images at submolecular resolution and associate function with the structures imaged after the SFM experiment is completed

Low-field magnetoresistance in GaAs 2D holes

We report low-field magnetotransport data in two-dimensional hole systems in GaAs/AlGaAs heterostructures and quantum wells, in a large density range, $2.5 \times 10^{10} \leq p \leq 4.0 \times 10^{11}$ cm$^{-2}$, with primary focus on samples grown on (311)A GaAs substrates. At high densities, $p \gtrsim 1 \times 10^{11}$ cm$^{-2}$, we observe a remarkably strong positive magnetoresistance. It appears in samples with an anisotropic in-plane mobility and predominantly along the low-mobility direction, and is strongly dependent on the perpendicular electric field and the resulting spin-orbit interaction induced spin-subband population difference. A careful examination of the data reveals that the magnetoresistance must result from a combination of factors including the presence of two spin-subbands, a corrugated quantum well interface which leads to the mobility anisotropy, and possibly weak anti-localization. None of these factors can alone account for the observed positive magnetoresistance. We also present the evolution of the data with density: the magnitude of the positive magnetoresistance decreases with decreasing density until, at the lowest density studied ($p = 2.5 \times 10^{10}$ cm$^{-2}$), it vanishes and is replaced by a weak negative magnetoresistance.Comment: 8 pages, 8 figure

Sticky stuff : redefining bedform prediction in modern and ancient environments

This work was funded by the UK Natural Environment Research Council (NERC) under the COHBED project (NE/1027223/1). Paterson was funded by the Marine Alliance for Science and Technology for Scotland (MASTS).The dimensions and dynamics of subaqueous bedforms are well known for cohesionless sediments. However, the effect of physical cohesion imparted by cohesive clay within mixed sand-mud substrates has not been examined, despite its recognized influence on sediment stability. Here we present a series of controlled laboratory experiments to establish the influence of substrate clay content on subaqueous bedform dynamics within mixtures of sand and clay exposed to unidirectional flow. The results show that bedform dimensions and steepness decrease linearly with clay content, and comparison with existing predictors of bedform dimensions, established within cohesionless sediments, reveals significant over-prediction of bedform size for all but the lowermost clay contents examined. The profound effect substrate clay content has on bedform dimensions has a number of important implications for interpretation in a range of modern and ancient environments, including reduced roughness and bedform heights in estuarine systems and the often cited lack of large dune cross-sets in turbidites. The results therefore offer a step change in our understanding of bedform formation and dynamics in these, and many other, sedimentary environments.Publisher PDFPeer reviewe

Microbiological assessment and evaluation of rehydration instructions on powdered infant formulas, follow-up formulas, and infant foods in Malaysia

A total of 90 samples comprised of powdered infant formulas (51), follow-up formulas (21) and infant foods (18) from 15 domestic and imported brands were purchased from various retailers in Klang Valley, Malaysia and evaluated in terms of microbiological quality and the similarity of rehydration instructions on the product label to guidelines set by the World Health Organization. Microbiological analysis included the determination of aerobic plate count (APC) and the presence of Enterobacteriaceae and Cronobacter spp. Isolates of interest were identified using ID 32E (bioMerieux®). In this study 87% of powdered infant formulas, follow-up formulas and infant foods analyzed had aerobic plate counts below the permitted level of 70°C for formula preparation as specified by the 2008 revised World Health Organization guidelines. Six brands instructed the use of water at 40-55°C, a temperature range which would support the survival and even growth of Enterobacteriaceae

Laboratory study on the effects of hydro kinetic turbines on hydrodynamics and sediment dynamics

© 2018 The Authors The need for hydrokinetic turbine wake characterisation and their environmental impact has led to a number of studies. However, a small number of them have taken into account mobile sediment bed effects. The aim of the present work is to study the impact of the presence of a horizontal-axis three-bladed turbine with the flow and a mobile sediment bed. We use a series of laboratory experiments with a scaled modelled turbine installed in a flume with a mobile sandy bed at the bottom. Acoustic instruments were used to monitor flow, suspended sediment and bed behaviour. Results show a velocity decrease of about 50% throughout the water column and no flow recovery after a distance of 15 rotor diameters. Clearly visible ripples in the absence of the model turbine were replaced by horseshoe-shaped scour pit in the near wake region, and a depositional heap in the far wake. Suspended sediment differences were recorded in the streamwise direction with a possible effect of the wake as far as 15 rotor diameters. These results imply potentially important effects on the efficiency of turbine arrays, if the flow were to be lower than expected, on turbine foundations and modify coastal sediment transport

Spin polarization of strongly interacting 2D electrons: the role of disorder

In high-mobility silicon MOSFET's, the $g^*m^*$ inferred indirectly from magnetoconductance and magnetoresistance measurements with the assumption that $g^*\mu_BH_s=2E_F$ are in surprisingly good agreement with $g^*m^*$ obtained by direct measurement of Shubnikov-de Haas oscillations. The enhanced susceptibility $\chi^* \propto (g^*m^*)$ exhibits critical behavior of the form $\chi^* \propto (n - n_0)^{-\alpha}$. We examine the significance of the field scale $H_s$ derived from transport measurements, and show that this field signals the onset of full spin polarization only in the absence of disorder. Our results suggest that disorder becomes increasingly important as the electron density is reduced toward the transition.Comment: 4 pages, 3 figure

Correction to probing the quantum states of a single atom transistor at microwave frequencies

Abstract not availableGiuseppe Carlo Tettamanzi, Samuel James Hile, Matthew Gregory House, Martin Fuechsle, Sven Rogge, and Michelle Y. Simmon

Characterising wood properties for deployment of elite subtropical and tropical hardwoods.

Queensland has over 42,000 hectares of hardwood plantations, with 13,700 hectares currently managed for sawn timber and high-value products. Previously, a major impediment to expansion of the hardwood sawn timber and high-value products industry in Queensland was that improved varieties of the key subtropical and tropical species were not available for plantation establishment. Trees from earlier projects, such as Hardwoods Queensland and the Private Plantations Initiative, have now reached an age where selection for growth, form and wood properties is possible. The current project used non-destructive and destructive wood evaluation techniques to characterise the timber quality of 443 subtropical and tropical Corymbia and Eucalyptus trees in these plantings, allowing selection of trees with the best growth, form and wood properties under Queensland conditions. Ecological assessments were also undertaken in the Corymbia plantings to identify germplasm that posed minimal risk of gene flow into native forests. Elite varieties are being fast tracked for deployment in Queensland using economical systems for germplasm capture and nursery production. The project identified and captured 108 new Corymbia and Eucalyptus varieties that can be grown with confidence in Queensland over a shorter rotation length and which produce well-characterised high-quality hardwood timber

Existence and Stability of Symmetric Periodic Simultaneous Binary Collision Orbits in the Planar Pairwise Symmetric Four-Body Problem

We extend our previous analytic existence of a symmetric periodic simultaneous binary collision orbit in a regularized fully symmetric equal mass four-body problem to the analytic existence of a symmetric periodic simultaneous binary collision orbit in a regularized planar pairwise symmetric equal mass four-body problem. We then use a continuation method to numerically find symmetric periodic simultaneous binary collision orbits in a regularized planar pairwise symmetric 1, m, 1, m four-body problem for $m$ between 0 and 1. Numerical estimates of the the characteristic multipliers show that these periodic orbits are linearly stability when $0.54\leq m\leq 1$, and are linearly unstable when $0<m\leq0.53$.Comment: 6 figure

Study protocol for a natural experiment in a lower socioeconomic area to examine the health-related effects of refurbishment to parks including built-shade (ShadePlus)

INTRODUCTION: Parks in disadvantaged suburbs often have low quality and few amenities, which is likely to result in them being underutilised for recreation and physical activity. Refurbishment of parks, including shade, walking paths and other amenities, may have broad health-related benefits. METHODS AND ANALYSIS: The study design, methods and planned analyses for a natural experiment examining the effects of refurbishments including built-shade added to parks in disadvantaged outer suburbs of Melbourne are described. Three intervention parks and three comparison parks matched for equivalence of park and neighbourhood characteristics were selected. Using mixed methods, the outcomes will be assessed during three consecutive spring-summer periods (T1: 2013-2014; T2: 2014-2015: T3: 2015-2016). Primary outcomes included: observed park use, physical activity and shade use. Self-reported social connectedness, community engagement and psychological well-being were assessed as secondary outcomes. ETHICS AND DISSEMINATION: This study was approved by Cancer Council Victoria\u27s Human Research Ethics Committee. Studies such as ShadePlus can improve understanding of the broader effects of park refurbishments (including physical activity levels and sun protection behaviours, as well as social connectedness and psychological well-being). The study findings will be disseminated through established urban planning and parks and recreation networks, peer review publications and conference presentations