A new stall-onset criterion for low speed dynamic-stall

The Beddoes/Leishman dynamic-stall model has become one of the most popular for the provision of unsteady aerofoil data embedded in much larger codes. The underlying modeling philosophy was that it should be based on the best understanding, or description, of the associated physical phenomena. Even though the model was guided by the flow physics, it requires significant empirical inputs in the form of measured coefficients and constants. Beddoes provided these for a Mach number range of 0.3–0.8. This paper considers one such input for a Mach number of 0.12, where, from the Glasgow data, it is shown that the current stall-onset criterion, and subsequent adjustments, yield problematic results. A new stall criterion is proposed and developed in the best traditions of the model. It is shown to be very capable of reconstructing the Glasgow's data for stall onset both the ramp-up and oscillatory tests

Evaluation of nebulised hypertonic saline (7%) as an adjunct to physiotherapy in patients with stable bronchiectasis

AbstractSputum clearance is of prime importance in the management of patients with bronchiectasis. While nebulised normal isotonic saline (0.9%) (IS) has been anecdotally used to treat patients with tenacious sputum, the use of hypertonic saline (7%) (HS) could have potential muco-protective and clearance properties.24 patients with bronchiectasis were randomised to receive four single treatment schedules in random order: (1) active cycle breathing technique (ACBT) alone, (2) nebulised terbutaline then ACBT, (3) nebulised terbutaline, nebulised IS then ACBT and (4) nebulised terbutaline, nebulised HS then ACBT.Sputum weights were significantly higher after HS than IS (P=0.002). Ease of expectoration also differed overall (P=<0.0001) and was significantly lower with HS than with IS (P=0.0005). Sputum viscosity differed between treatment phases, with a significant linear trend to reduced sputum viscosity with HS (P=0.0002). These changes were associated with small but statistically significant differences in FEV1 (P=0.043) and FVC (P=0.011) between treatment phases.Nebulised hypertonic saline can be used safely and effectively as an adjunct to physiotherapy in selected patients. A long-term prospective trial is now indicated to determine its effectiveness on long-term infection rate, quality of life and lung function

Maximum-Entropy Weighting of Multi-Component Earth Climate Models

A maximum entropy-based framework is presented for the synthesis of projections from multiple Earth climate models. This identifies the most representative (most probable) model from a set of climate models -- as defined by specified constraints -- eliminating the need to calculate the entire set. Two approaches are developed, based on individual climate models or ensembles of models, subject to a single cost (energy) constraint or competing cost-benefit constraints. A finite-time limit on the minimum cost of modifying a model synthesis framework, at finite rates of change, is also reported.Comment: Inspired by discussions at the Mathematical and Statistical Approaches to Climate Modelling and Prediction workshop, Isaac Newton Institute for Mathematical Sciences, Cambridge, UK, 11 Aug. to 22 Dec. 2010. Accepted for publication in Climate Dynamics, 8 August 201

Severe vocal cord dysfunction resistant to all current therapeutic interventions

SummaryVocal cord dysfunction (VCD) is characterised by paradoxical vocal cord adduction during inspiration or throughout the respiratory cycle, it results in wheeze, stridor, cough and dyspnoea. Although asthma and VCD can coexist, patients with VCD are frequently misdiagnosed with refractory asthma. It can severely restrict an individual's level of activity and effective therapeutic control can be difficult to achieve. We report the case of a patient who was treated with all available therapeutic interventions, including intralaryngeal botulinum toxin injection, but failure resulted in a permanent trachesotomy

The f-vector of the descent polytope

For a positive integer n and a subset S of [n-1], the descent polytope DP_S is the set of points x_1, ..., x_n in the n-dimensional unit cube [0,1]^n such that x_i >= x_{i+1} for i in S and x_i <= x_{i+1} otherwise. First, we express the f-vector of DP_S as a sum over all subsets of [n-1]. Second, we use certain factorizations of the associated word over a two-letter alphabet to describe the f-vector. We show that the f-vector is maximized when the set S is the alternating set {1,3,5, ...}. We derive a generating function for the f-polynomial F_S(t) of DP_S, written as a formal power series in two non-commuting variables with coefficients in Z[t]. We also obtain the generating function for the Ehrhart polynomials of the descent polytopes.Comment: 14 pages; to appear in Discrete & Computational Geometr