Morphological hysteresis in the evolution of beach profiles under sequences of wave climates - Part 1; observations

Novel series of experiments are presented that demonstrate morphological hysteresis in the evolution to equilibrium of beach profiles under sequences of different wave climates. The experiments were conducted in a wave flume at medium scale using both monochromatic and random waves, representing 2D conditions. Beach profiles were obtained with high spatial resolution at frequent intervals with a laser profiler, from which shoreline location, bar position and sediment transport rates were derived. Experiments were conducted for sequences of wave climates, where a sequence comprised of 6-13 sequential tests, each commencing with the beach profile from the preceding test. Each test was run until equilibrium conditions were obtained and had a constant wave height, increased or decreased relative to the preceding test. Cyclical conditions were also included, with erosive and accretive wave conditions of short durations alternating through multiple cycles, so that equilibrium conditions were not reached during a test. With a sequence of increasing wave heights, the relationship between the shoreline position and the bulk cross-shore sediment transport, at equilibrium, was non-monotonic, indicating a maximum in the landward sediment transport rate. For test series comprised of a sequence of increasing wave heights followed by a sequence of decreasing wave heights, morphological hysteresis was observed in the equilibrium shoreline position and bulk cross-shore sediment transport, such that shoreline recession, or offshore transport, continued in some instances after reductions in wave height. This is inconsistent with classical equilibritim type shoreline evolution models. However, when equilibrium conditions were not reached, in the cyclic sequences, no such morphological hysteresis was observed and a dynamic equilibrium is reached. The morphological hysteresis occurs because of the decay, stranding, or increased relative depth, of the breaker bar following a reduction in wave height, often in conjunction with a new breaker bar generated by further offshore transport in the inner surf zone. Similar sequences of morphological response are evident in field data and larger scale tests in the literature. Finally, it is shown that the morphological hysteresis can be explained using the classical equilibrium beach state model of Wright et al. (1985) by introducing the concept of a subsequent alternate active beach state, which may occur following a change in wave conditions

Analysis of strain and stacking faults in single nanowires using Bragg coherent diffraction imaging

Coherent diffraction imaging (CDI) on Bragg reflections is a promising technique for the study of three-dimensional (3D) composition and strain fields in nanostructures, which can be recovered directly from the coherent diffraction data recorded on single objects. In this article we report results obtained for single homogeneous and heterogeneous nanowires with a diameter smaller than 100 nm, for which we used CDI to retrieve information about deformation and faults existing in these wires. The article also discusses the influence of stacking faults, which can create artefacts during the reconstruction of the nanowire shape and deformation.Comment: 18 pages, 6 figures Submitted to New Journal of Physic

Magnetic-field-induced Luttinger liquid

It is shown that a strong magnetic field applied to a bulk metal induces a Luttinger-liquid phase. This phase is characterized by the zero-bias anomaly in tunneling: the tunneling conductance scales as a power-law of voltage or temperature. The tunneling exponent increases with the magnetic field as BlnB. The zero-bias anomaly is most pronounced for tunneling with the field applied perpendicular to the plane of the tunneling junction.Comment: a reference added, minor typos correcte

Modelling Future Coronary Heart Disease Mortality to 2030 in the British Isles.

OBJECTIVE: Despite rapid declines over the last two decades, coronary heart disease (CHD) mortality rates in the British Isles are still amongst the highest in Europe. This study uses a modelling approach to compare the potential impact of future risk factor scenarios relating to smoking and physical activity levels, dietary salt and saturated fat intakes on future CHD mortality in three countries: Northern Ireland (NI), Republic of Ireland (RoI) and Scotland. METHODS: CHD mortality models previously developed and validated in each country were extended to predict potential reductions in CHD mortality from 2010 (baseline year) to 2030. Risk factor trends data from recent surveys at baseline were used to model alternative future risk factor scenarios: Absolute decreases in (i) smoking prevalence and (ii) physical inactivity rates of up to 15% by 2030; relative decreases in (iii) dietary salt intake of up to 30% by 2030 and (iv) dietary saturated fat of up to 6% by 2030. Probabilistic sensitivity analyses were then conducted. RESULTS: Projected populations in 2030 were 1.3, 3.4 and 3.9 million in NI, RoI and Scotland respectively (adults aged 25-84). In 2030: assuming recent declining mortality trends continue: 15% absolute reductions in smoking could decrease CHD deaths by 5.8-7.2%. 15% absolute reductions in physical inactivity levels could decrease CHD deaths by 3.1-3.6%. Relative reductions in salt intake of 30% could decrease CHD deaths by 5.2-5.6% and a 6% reduction in saturated fat intake might decrease CHD deaths by some 7.8-9.0%. These projections remained stable under a wide range of sensitivity analyses. CONCLUSIONS: Feasible reductions in four cardiovascular risk factors (already achieved elsewhere) could substantially reduce future coronary deaths. More aggressive polices are therefore needed in the British Isles to control tobacco, promote healthy food and increase physical activity

Effect of glass on the frictional behavior of basalts at seismic slip rates

We performed 31 friction experiments on glassy basalts (GB) and glass-free basalts (GFB) at slip rates up to 6.5 m s−1 and normal stress up to 40 MPa (seismic conditions). Frictional weakening was associated to bulk frictional melting and lubrication. The weakening distance (Dw) was about 3 times shorter in GB than in GFB, but the steady state friction was systematically higher in GB than in GFB. The shorter Dw in GB may be explained by the thermal softening occurring at the glass transition temperature (Tg ~500°C), which is lower than the bulk melting temperature (Tm ~1250°C) of GFB. Postexperiment microanalyses suggest that the larger crystal fraction measured in GB melts results in the higher steady state friction value compared to the GFB melts. The effect of interstitial glass is to facilitate frictional instability and rupture propagation in GB with respect to GFB

Conceptualizing pathways linking women's empowerment and prematurity in developing countries.

BackgroundGlobally, prematurity is the leading cause of death in children under the age of 5. Many efforts have focused on clinical approaches to improve the survival of premature babies. There is a need, however, to explore psychosocial, sociocultural, economic, and other factors as potential mechanisms to reduce the burden of prematurity. Women's empowerment may be a catalyst for moving the needle in this direction. The goal of this paper is to examine links between women's empowerment and prematurity in developing settings. We propose a conceptual model that shows pathways by which women's empowerment can affect prematurity and review and summarize the literature supporting the relationships we posit. We also suggest future directions for research on women's empowerment and prematurity.MethodsThe key words we used for empowerment in the search were "empowerment," "women's status," "autonomy," and "decision-making," and for prematurity we used "preterm," "premature," and "prematurity." We did not use date, language, and regional restrictions. The search was done in PubMed, Population Information Online (POPLINE), and Web of Science. We selected intervening factors-factors that could potentially mediate the relationship between empowerment and prematurity-based on reviews of the risk factors and interventions to address prematurity and the determinants of those factors.ResultsThere is limited evidence supporting a direct link between women's empowerment and prematurity. However, there is evidence linking several dimensions of empowerment to factors known to be associated with prematurity and outcomes for premature babies. Our review of the literature shows that women's empowerment may reduce prematurity by (1) preventing early marriage and promoting family planning, which will delay age at first pregnancy and increase interpregnancy intervals; (2) improving women's nutritional status; (3) reducing domestic violence and other stressors to improve psychological health; and (4) improving access to and receipt of recommended health services during pregnancy and delivery to help prevent prematurity and improve survival of premature babies.ConclusionsWomen's empowerment is an important distal factor that affects prematurity through several intervening factors. Improving women's empowerment will help prevent prematurity and improve survival of preterm babies. Research to empirically show the links between women's empowerment and prematurity is however needed

Optically-guided frameless linac-based radiosurgery for brain metastases: clinical experience

The purpose of this study was to describe our clinical experience using optically-guided linear accelerator (linac)-based frameless stereotactic radiosurgery (SRS) for the treatment of brain metastases. Sixty-five patients (204 lesions) were treated between 2005 and 2008 with frameless SRS using an optically-guided bite-block system. Patients had a median of 2 lesions (range, 1–13). Prescription dose ranged from 14 to 22 Gy (median, 18 Gy) and was given in a single fraction. Clinical and radiographic evaluation occurred every 2–4 months following treatment. At a median follow-up of 6.2 months, actuarial survival at 12 months was 40% [95% confidence interval (CI), 28–52). Of 135 lesions that were evaluable for local control (LC), 119 lesions (88%) did not show evidence of progression. Actuarial 12 month LC was 76% (95% CI, 66–86). Tumors ≤2 cm in size had a better 12 month LC rate (81% vs. 36%, P = 0.017) than those >2 cm. Adverse events occurred in three patients (5%). Optically-guided linac-based frameless SRS can produce clinical outcomes that compare favorably to frame-based techniques. As this technique is convenient to use and allows for the uncomplicated delivery of hypofractionated radiotherapy, frameless SRS will likely have an increasingly important role in the management of brain metastases

Osteoprotegerin: A Novel Secreted Protein Involved in the Regulation of Bone Density

AbstractA novel secreted glycoprotein that regulates bone resorption has been identified. The protein, termed Osteoprotegerin (OPG), is a novel member of the TNF receptor superfamily. In vivo, hepatic expression of OPG in transgenic mice results in a profound yet nonlethal osteopetrosis, coincident with a decrease in later stages of osteoclast differentiation. These same effects are observed upon administration of recombinant OPG into normal mice. In vitro, osteoclast differentiation from precursor cells is blocked in a dose-dependent manner by recombinant OPG. Furthermore, OPG blocks ovariectomy-associated bone loss in rats. These data show that OPG can act as a soluble factor in the regulation of bone mass and imply a utility for OPG in the treatment of osteoporosis associated with increased osteoclast activity