Direct characterisation of tuneable few-femtosecond dispersive-wave pulses in the deep UV

Dispersive wave emission (DWE) in gas-filled hollow-core dielectric waveguides is a promising source of tuneable coherent and broadband radiation, but so far the generation of few-femtosecond pulses using this technique has not been demonstrated. Using in-vacuum frequency-resolved optical gating, we directly characterise tuneable 3fs pulses in the deep ultraviolet generated via DWE. Through numerical simulations, we identify that the use of a pressure gradient in the waveguide is critical for the generation of short pulses.Comment: 5 pages, 4 figure

Sequence Effects on DNA Entropic Elasticity

DNA stretching experiments are usually interpreted using the worm-like chain model; the persistence length A appearing in the model is then interpreted as the elastic stiffness of the double helix. In fact the persistence length obtained by this method is a combination of bend stiffness and intrinsic bend effects reflecting sequence information, just as at zero stretching force. This observation resolves the discrepancy between the value of A measured in these experiments and the larger ``dynamic persistence length'' measured by other means. On the other hand, the twist persistence length deduced from torsionally-constrained stretching experiments suffers no such correction. Our calculation is very simple and analytic; it applies to DNA and other polymers with weak intrinsic disorder.Comment: LaTeX; postscript available at http://dept.physics.upenn.edu/~nelson/index.shtm

Modelling curved-layered printing paths for fabricating large-scale construction components

In this paper, a non-conventional way of additive manufacturing, curved-layered printing, has been applied to large-scale construction process. Despite the number of research works on Curved Layered Fused Deposition Modelling (CLFDM) over the last decade, few practical applications have been reported. An alternative method adopting the CLFDM principle, that generates a curved-layered printing path, was developed using a single scripting environment called Grasshopper – a plugin of Rhinoceros® . The method was evaluated with the 3D Concrete Printing process developed at Loughborough University. The evaluation of the method including the results of simulation and printing revealed three principal benefits compared with existing flat-layered printing paths, which are particularly beneficial to large-scale AM techniques: (i) better surface quality, (ii) shorter printing time and (iii) higher surface strengths

Risk of myocardial infarction and ischemic stroke in individuals with first-diagnosed paroxysmal vs. non-paroxysmal atrial fibrillation under anticoagulation

AimsThere is conflicting evidence on whether the type of atrial fibrillation (AF) is associated with risk of cardiovascular events, including acute myocardial infarction (MI) and ischemic stroke. The aim of the present study was to investigate whether the risk of MI and ischemic stroke differs between individuals with first-diagnosed paroxysmal vs. non-paroxysmal AF treated with anticoagulants.Methods and resultsDe-identified electronic medical records from the TriNetX federated research network were used. Individuals with a new diagnosis of paroxysmal AF who had no evidence of other types of AF in their records were 1:1 propensity score-matched with individuals with non-paroxysmal AF, defined as persistent or chronic AF, who had no evidence of other types of AF in their records. All patients were followed for three years for the outcomes of MI and ischemic stroke. Cox proportional hazard models were used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs). In the propensity-matched cohort, among 24 848 well-matched AF individuals [mean age 74.4 ± 10.4; 10 101 (40.6%) female], 410 (1.7%) were diagnosed with acute MI and 875 (3.5%) with ischemic stroke during the three-year follow-up. Individuals with paroxysmal AF had significantly higher risk of acute MI (HR: 1.65, 95%CI: 1.35-2.01) compared to those with non-paroxysmal AF. First diagnosed paroxysmal AF was associated with higher risk of non-ST elevation MI (nSTEMI) (HR: 1.89, 95%CI: 1.44-2.46). No significant association was observed between the type of AF and risk of ischemic stroke (HR: 1.09, 95%CI: 0.95-1.25).ConclusionPatients with first-diagnosed paroxysmal AF had higher risk of acute MI compared to individuals with non-paroxysmal AF, attributed to the higher risk of nSTEMI among patients with first-diagnosed paroxysmal AF. There was no significant association between type of AF and risk of ischemic stroke

Predicting tree distributions in an East African biodiversity hotspot : model selection, data bias and envelope uncertainty

The Eastern Arc Mountains (EAMs) of Tanzania and Kenya support some of the most ancient tropical rainforest on Earth. The forests are a global priority for biodiversity conservation and provide vital resources to the Tanzanian population. Here, we make a first attempt to predict the spatial distribution of 40 EAM tree species, using generalised additive models, plot data and environmental predictor maps at sub 1 km resolution. The results of three modelling experiments are presented, investigating predictions obtained by (1) two different procedures for the stepwise selection of predictors, (2) down-weighting absence data, and (3) incorporating an autocovariate term to describe fine-scale spatial aggregation. In response to recent concerns regarding the extrapolation of model predictions beyond the restricted environmental range of training data, we also demonstrate a novel graphical tool for quantifying envelope uncertainty in restricted range niche-based models (envelope uncertainty maps). We find that even for species with very few documented occurrences useful estimates of distribution can be achieved. Initiating selection with a null model is found to be useful for explanatory purposes, while beginning with a full predictor set can over-fit the data. We show that a simple multimodel average of these two best-model predictions yields a superior compromise between generality and precision (parsimony). Down-weighting absences shifts the balance of errors in favour of higher sensitivity, reducing the number of serious mistakes (i.e., falsely predicted absences); however, response functions are more complex, exacerbating uncertainty in larger models. Spatial autocovariates help describe fine-scale patterns of occurrence and significantly improve explained deviance, though if important environmental constraints are omitted then model stability and explanatory power can be compromised. We conclude that the best modelling practice is contingent both on the intentions of the analyst (explanation or prediction) and on the quality of distribution data; generalised additive models have potential to provide valuable information for conservation in the EAMs, but methods must be carefully considered, particularly if occurrence data are scarce. Full results and details of all species models are supplied in an online Appendix. (C) 2008 Elsevier B.V. All rights reserved

An investigation of Australian osteopaths' attitudes, skills and utilisation of evidence-based practice: a national cross-sectional survey

© 2019 The Author(s). Background: Osteopaths are an integral member of the health care team, playing a pivotal role in the provision of care for patients with musculoskeletal disorders. Osteopaths, like other health care providers, are under increasing pressure to deliver evidence-based health care and to improve patient outcomes. However, the extent to which osteopaths engage in evidence-based practice (EBP), particularly in Australia, is not well understood. This study therefore set out to investigate the attitudes, skills and use of EBP, and perceived barriers and enablers of EBP uptake, among osteopaths practicing in Australia. Methods: National cross-sectional survey of Australian registered osteopaths. Eligible participants were invited by email and other digital media recruitment strategies to complete the online Evidence-Based Practice Attitude and Utilisation Survey (EBASE). Results: A total of 332 osteopaths completed the survey. The demographic characteristics of respondents were generally consistent with the characteristics of the Australian osteopathy workforce. The respondents were mostly favourable of EBP, with the majority agreeing or strongly agreeing that EBP assists in making decisions about patient care (86.7%) and improves the quality of patient care (75.6%). While most respondents (88.3%) had some training in EBP, most reported a moderate level of perceived skill in EBP. The majority of respondents engaged infrequently (0-5 times) in EBP activities within the last month, and most indicated that a very small or small proportion of their clinical practice was based on clinical research evidence. Leading barriers to the uptake of EBP were lack of time and lack of clinical evidence in osteopathy. Key enablers of EBP uptake were access to the internet and online databases at work, and access to full-text articles and EBP education materials. Conclusions: Osteopaths participating in the survey were largely supportive of evidence-based practice, yet engaged infrequently in EBP activities. An important next step in this research is to identify suitable strategies that effectively improve EBP uptake in osteopathy, and perchance, improve patient outcomes

Structure-activity relationships of the sustained effects of adenosine A2A receptor agonists driven by slow dissociation kinetics

The duration of action of adenosine A2A receptor (A2A) agonists is critical for their clinical efficacy, and we sought to better understand how this can be optimized. The in vitro temporal response profiles of a panel of A2A agonists were studied using cAMP assays in recombinantly (CHO) and endogenously (SH-SY5Y) expressing cells. Some agonists (e.g., 3cd; UK-432,097) but not others (e.g., 3ac; CGS-21680) demonstrated sustained wash-resistant agonism, where residual receptor activation continued after washout. The ability of an antagonist to reverse pre-established agonist responses was used as a surrogate read-out for agonist dissociation kinetics, and together with radioligand binding studies suggested a role for slow off-rate in driving sustained effects. One compound, 3ch, showed particularly marked sustained effects, with a reversal t1/2 > 6 hours and close to maximal effects that remained for at least 5 hours after washing. Based on the structure-activity relationship of these compounds, we suggest that lipophilic N6 and bulky C2 substituents can promote stable and long-lived binding events leading to sustained agonist responses, although a high compound logD is not necessary. This provides new insight into the binding interactions of these ligands and we anticipate that this information could facilitate the rational design of novel long-acting A2A agonists with improved clinical efficacy

Overlay Design and Reflection Cracking Analysis for Rigid Pavements Vol. 1. Development of New Design Criteria

DOT-FH-11-8544Fatigue cracking and reflection cracking criteria were developed and incorporated into a design procedure for flexible and rigid overlays of rigid pavements. Linear elastic layered theory is the basic model used to compute stresses and strains in the pavement system, which are then input to the fatigue and reflection cracking models. The fatigue criteria developments resulted from analyses of the performance of rigid pavements at the AASHO Road Test. A regression analysis was performed to obtain a fatigue equation relating stress and wheel load repetitions prior to Class 3 and 4 cracking. The effects of voids beneath the pavement as well as the condition of joints are also considered in the fatigue criteria. The reflection cracking criteria developed resulted from a study of the mechanics of reflection cracking and literature reviews. Mechanistic equations were derived and incorporated into an analysis model for use in design

Carbon stable isotope analysis of cereal remains as a way to reconstruct water availability: preliminary results

Reconstructing past water availability, both as rainfall and irrigation, is important to answer questions about the way society reacts to climate and its changes and the role of irrigation in the development of social complexity. Carbon stable isotope analysis of archaeobotanical remains is a potentially valuable method for reconstructing water availability. To further define the relationship between water availability and plant carbon isotope composition and to set up baseline values for the Southern Levant, grains of experimentally grown barley and sorghum were studied. The cereal crops were grown at three stations under five different irrigation regimes in Jordan. Results indicate that a positive but weak relationship exists between irrigation regime and total water input of barley grains, but no relationship was found for sorghum. The relationship for barley is site-specific and inter-annual variation was present at Deir ‘Alla, but not at Ramtha and Khirbet as-Samra