On the dependence of the avalanche angle on the granular layer thickness

A layer of sand of thickness h flows down a rough surface if the inclination is larger than some threshold value theta which decreases with h. A tentative microscopic model for the dependence of theta with h is proposed for rigid frictional grains, based on the following hypothesis: (i) a horizontal layer of sand has some coordination z larger than a critical value z_c where mechanical stability is lost (ii) as the tilt angle is increased, the configurations visited present a growing proportion $_s of sliding contacts. Instability with respect to flow occurs when z-z_s=z_c. This criterion leads to a prediction for theta(h) in good agreement with empirical observations.Comment: 6 pages, 2 figure

A systematic review of the physical activity assessment tools used in primary care

Background: Primary care is an ideal setting for physical activity interventions to prevent and manage common long-term conditions. To identify those who can benefit from such interventions and to deliver tailored support, primary care professionals (e.g. general practitioners, practice nurses, physiotherapists, healthcare assistants) need reliable and valid tools to assess physical activity. However, there is uncertainty about the best performing tool. Objective: To identify the tools used in the literature to assess the physical activity in primary care and describe their psychometric properties. Method: A systematic review of published and unpublished literature was undertaken up to 1st December 2016). Papers detailing physical activity measures, tools or approaches used in primary care consultations were included. A synthesis of the frequency and context of their use, and their psychometric properties, was undertaken. Studies were appraised using the Downs and Black critical appraisal tool and the COnsensus-based Standards for the selection of health Measurement Instruments (COSMIN) initiative checklist. Results: Fourteen papers reported 10 physical activity assessment tools. The General Practice Physical Activity Questionnaire (GPPAQ) was most frequently reported. None of the assessment tools identified showed high reliability and validity. Intra-rater reliability ranged from Kappa: 0.53 (Brief Physical Activity Assessment Tool (BPAAT)) to 0.67 (GPPAQ). Criterion validity ranged from Pearson’s Rho: 0.26 (GPPAQ) to 0.52 (Physical Activity Vital Sign). Concurrent validity ranged from Kappa: 0.24 (GPPAQ) to 0.64 (BPAAT). Conclusion: The evidence base about physical activity assessment in primary care is insufficient to inform current practice

Effects of laser prepulses on laser-induced proton generation

Low-intensity laser prepulses (<10(13) W cm(-2), nanosecond duration) are a major issue in experiments on laser-induced generation of protons, often limiting the performances of proton sources produced by high-intensity lasers (approximate to 10(19) W cm(-2), picosecond or femtosecond duration). Depending on the intensity regime, several effects may be associated with the prepulse, some of which are discussed in this paper: (i) destruction of thin foil targets by the shock generated by the laser prepulse; (ii) creation of preplasma on the target front side affecting laser absorption; (iii) deformation of the target rear side; and (iv) whole displacement of thin foil targets affecting the focusing condition. In particular, we show that under oblique high-intensity irradiation and for low prepulse intensities, the proton beam is directed away from the target normal. Deviation is towards the laser forward direction, with an angle that increases with the level and duration of the ASE pedestal. Also, for a given laser pulse, the beam deviation increases with proton energy. The observations are discussed in terms of target normal sheath acceleration, in combination with a laser-controllable shock wave locally deforming the target surface

Gastric Prolapse with Pseudocysts Following Laparoscopic Adjustable Gastric Banding

Nonpancreatic pseudocysts may be associated with gastric prolapse in patients who have undergone laparoscopic adjustable gastric banding

Cognitive Performance in Midlife Type 2 Diabetes: Results form the ENBIND Study

Aims: To establish the impact of uncomplicated type 2 diabetes on cognitive and neuropsychological performance in midlife. Methods: We performed a cross-sectional study of middle-aged adults with uncomplicated type 2 diabetes and a cohort of healthy control participants. General cognition was assessed using the Montreal Cognitive Assessment test and neuropsychological assessment was undertaken using a detailed neuropsychological assessment battery. Results: A total of 152 participants (102 with type 2 diabetes and 50 controls) were recruited (mean age 52 ± 8 years, 51% women). Participants with midlife type 2 diabetes were more than twice as likely to make an error on the Montreal Cognitive Assessment test [incidence rate ratio 2.44 (95% CI 1.54 to 3.87); P \u3c 0.001]. Further, type 2 diabetes was also associated with significantly lower memory composite score [β: −0.20 (95% CI −0.39 to −0.01); P = 0.04] and paired associates learning score [β: = −1.97 (95% CI −3.51, −0.43); P = 0.01] on the neuropsychological assessment battery following adjustment for age, sex, BMI, educational attainment and hypercholesterolaemia. Conclusions: Even in midlife, type 2 diabetes was associated with small but statistically significant cognitive decrements. These statistically significant decrements, whilst not clinically significant in terms of objective cognitive impairment, may have important implications in selecting out individuals most at risk of later cognitive decline for potential preventative interventions in midlife

Laser pulse propagation and enhanced energy coupling to fast electrons in dense plasma gradients

Laser energy absorption to fast electrons during the interaction of an ultra-intense (1020 W/cm2), picosecond laser pulse with a solid is investigated, experimentally and numerically, as a function of the plasma density scale length at the irradiated surface. It is shown that there is an optimum density gradient for efficient energy coupling to electrons and that this arises due to strong self-focusing and channeling driving energy absorption over an extended length in the preformed plasma. At longer density gradients the laser laments, resulting in significantly lower overall energy coupling. As the scale length is further increased, a transition to a second laser energy absorption process is observed experimentally via multiple diagnostics. The results demonstrate that it is possible to significantly enhance laser energy absorption and coupling to fast electrons by dynamically controlling the plasma density gradient

Molecular associations in acacia gums

The tendency of polysaccharides to associate in aqueous solution has long been recognised. Molecular associations can profoundly affect their performance in a given application due to its influence on the molecular weight, shape and size. This will ultimately determine how the molecules will interact with each other, with other molecules and with water. There are several factors, such as hydrogen bonding, hydrophobic association, ion mediated association, electrostatic interaction, concentration dependence and the presence of proteinaceous components, which affect this behaviour. Our objective is to highlight the role of the proteinaceous component, present in acacia gum, to promote associations when the gum is subjected to various processing treatments such as maturation, spray drying and irradiation. The results demonstrate the ability of the proteinaceous component to promote hydrophobic associations which influence the size and proportion of the arabinogalactan high molecular weight component (AGP). Heat treatment in solid state (maturation) increases the hydrophobic character of the gum and hence its emulsification performance. Spray drying also involves aggregation through hydrophobic association but changes the surface properties of peptide moieties to become more hydrophilic compared to the association promoted by the maturation treatment in the solid state. Irradiation induced cross-linking, in the presence of unsaturated gas, was used to introduce C-C bonds into the carbohydrate moiety and thus confirms the hydrophobic association prompted by the heat used in the maturation and spray drying. This association can be reversed by treatments such as filtration or high pressure homogenisation. The results reported here reconcile the contradiction about structure of gum arabic proposed by the wattle blossom and twisted hairy rope models and shows that the AGP fraction is basically an aggregated fraction made up of AG units stabilised by low molecular weight highly proteinaceous components.

On the risk of studying practices in isolation: Linking what, who and how in strategy research

This paper challenges the recent focus on practices as stand-alone phenomena, as exemplified by the so-called “Practice-Based View of Strategy (PBV)” by Bromiley and Rau (2014). While the goal of “PBV” points to the potential of standard practices to generate performance differentials (in contrast to the Resource Based View), it marginalizes wellknown insights from practice theory more widely. In particular, by limiting its focus to practices, i.e. “what” practices are used, it underplays the implications of “who” is engaged in the practices and “how” the practices are carried out. In examining practices in isolation, the “PBV” carries the serious risk of misattributing performance differentials. In this paper, we offer an integrative practice perspective on strategy and performance that should aid scholars in generating more precise and contextually-sensitive theories about the enactment and impact of practices as well as about critical factors shaping differences in practice outcomes

Thermodynamic picture of the glassy state

A picture for thermodynamics of the glassy state is introduced. It assumes that one extra parameter, the effective temperature, is needed to describe the glassy state. This explains the classical paradoxes concerning the Ehrenfest relations and the Prigogine-Defay ratio. As a second part, the approach connects the response of macroscopic observables to a field change with their temporal fluctuations, and with the fluctuation-dissipation relation, in a generalized non-equilibrium way.Comment: Proceedings of the Conference "Unifying Concepts in Glass Physics", ICTP, Trieste, 15 - 18 September 199