Analysis of a General Family of Regularized Navier-Stokes and MHD Models

We consider a general family of regularized Navier-Stokes and Magnetohydrodynamics (MHD) models on n-dimensional smooth compact Riemannian manifolds with or without boundary, with n greater than or equal to 2. This family captures most of the specific regularized models that have been proposed and analyzed in the literature, including the Navier-Stokes equations, the Navier-Stokes-alpha model, the Leray-alpha model, the Modified Leray-alpha model, the Simplified Bardina model, the Navier-Stokes-Voight model, the Navier-Stokes-alpha-like models, and certain MHD models, in addition to representing a larger 3-parameter family of models not previously analyzed. We give a unified analysis of the entire three-parameter family using only abstract mapping properties of the principle dissipation and smoothing operators, and then use specific parameterizations to obtain the sharpest results. We first establish existence and regularity results, and under appropriate assumptions show uniqueness and stability. We then establish results for singular perturbations, including the inviscid and alpha limits. Next we show existence of a global attractor for the general model, and give estimates for its dimension. We finish by establishing some results on determining operators for subfamilies of dissipative and non-dissipative models. In addition to establishing a number of results for all models in this general family, the framework recovers most of the previous results on existence, regularity, uniqueness, stability, attractor existence and dimension, and determining operators for well-known members of this family.Comment: 37 pages; references added, minor typos corrected, minor changes to revise for publicatio

Efficacy and safety of ciclosporin versus methotrexate in the treatment of severe atopic dermatitis in children and young people (TREAT): a multicentre parallel group assessor-blinded clinical trial

Background Conventional systemic drugs are used to treat children and young people (CYP) with severe atopic dermatitis (AD) worldwide, but no robust randomized controlled trial (RCT) evidence exists regarding their efficacy and safety in this population. While novel therapies have expanded therapeutic options, their high cost means traditional agents remain important, especially in lower-resource settings. Objectives To compare the safety and efficacy of ciclosporin (CyA) with methotrexate (MTX) in CYP with severe AD in the TREatment of severe Atopic Eczema Trial (TREAT) trial. Methods We conducted a parallel group assessor-blinded RCT in 13 UK and Irish centres. Eligible participants aged 2–16 years and unresponsive to potent topical treatment were randomized to either oral CyA (4 mg kg–1 daily) or MTX (0.4 mg kg–1 weekly) for 36 weeks and followed-up for 24 weeks. Co-primary outcomes were change from baseline to 12 weeks in Objective Severity Scoring of Atopic Dermatitis (o-SCORAD) and time to first significant flare (relapse) after treatment cessation. Secondary outcomes included change in quality of life (QoL) from baseline to 60 weeks; number of participant-reported flares following treatment cessation; proportion of participants achieving ≥ 50% improvement in Eczema Area and Severity Index (EASI 50) and ≥ 75% improvement in EASI (EASI 75); and stratification of outcomes by filaggrin status. Results In total, 103 participants were randomized (May 2016–February 2019): 52 to CyA and 51 to MTX. CyA showed greater improvement in disease severity by 12 weeks [mean difference in o-SCORAD –5.69, 97.5% confidence interval (CI) –10.81 to –0.57 (P = 0.01)]. More participants achieved ≥ 50% improvement in o-SCORAD (o-SCORAD 50) at 12 weeks in the CyA arm vs. the MTX arm [odds ratio (OR) 2.60, 95% CI 1.23–5.49; P = 0.01]. By 60 weeks MTX was superior (OR 0.33, 95% CI 0.13–0.85; P = 0.02), a trend also seen for ≥ 75% improvement in o-SCORAD (o-SCORAD 75), EASI 50 and EASI 75. Participant-reported flares post-treatment were higher in the CyA arm (OR 3.22, 95% CI 0.42–6.01; P = 0.02). QoL improved with both treatments and was sustained after treatment cessation. Filaggrin status did not affect outcomes. The frequency of adverse events (AEs) was comparable between both treatments. Five (10%) participants on CyA and seven (14%) on MTX experienced a serious AE. Conclusions Both CyA and MTX proved effective in CYP with severe AD over 36 weeks. Participants who received CyA showed a more rapid response to treatment, while MTX induced more sustained disease control after discontinuation

An empirical note on one aspect of labour market hysteresis

One of the principal rationales for unemployment hysteresis focuses on the characterization of the labour market as consisting of insiders who possess wage negotiating power and outsiders who do not. A measure of bargaining power of insiders is overtime and this variable was found to be a significant determinant of wage inflation by Simes and Richardson (1987). Whereas their analysis dealt with aggregate national wage and overtime data the current paper investigates the possibility that relative overtime worked at the industry level may be a significant determinant of differential interindustry wages growth

Is US Monetary Growth a Leading Indicator of Australian Monetary Growth?

For an open economy the existence of internationally integrated goods and capital markets implies the country's monetary growth may be considerably influenced by fluctuations in international monetary circumstances. Theoretical literature exists which suggests US monetary growth may be catalytic in determining world monetary growth in general and the monetary growth of smaller. dependent economies in particular. In this paper, prima facie Australian statistical evidence is found which is consistent with this postulate. The lag in the association is identified and a model specified and estimated. A post‐sample validation period supports and strengthens the within‐sample results. Copyrigh

An Empirical Note on one Aspect of Labour Market Hysteresis

One of the principal rationales for unemployment hysteresis focuses on the characterization of the labour market as consisting of insiders who possess wage negotiating power and outsiders who do not. A measure of bargaining power of insiders is overtime and this variable was found to be a significant determinant of wage inflation by Simes and Richardson (1987). Whereas their analysis dealt with aggregate national wage and overtime data, the current paper investigates the possibility that relative overtime worked at the industry level may be a significant determinant of differential interindustry wages growth.

Effectiveness of seat belt legislation on the queensland road toll—an australian case study in intervention analysis

The effect of seat belt legislation introduced in the state of Queensland was examined by using two approaches. The first approach consisted of modeling time series of road deaths before intervention (the legislation) as a Box-Jenkins univariate time series model. As we expected, this model proved to be inadequate in explaining the postintervention period, and the model was modified to incorporate the expected form of the intervention effects. Results showed that the legislation produced significant reduction in the road toll, but this analytical approach was limited in describing long-run effects. The second approach, involving causal model and incorporating a proxy explanatory variable and autoregressive-moving average error, was fruitful in overcoming the limitation of the previous approach. The long-run legislative effect was quantified, at a specific level of the explanatory variable, to be a 46 percent reduction in deaths

On the Real Exchange Rate as a Measure of Australia's External Competitiveness

The use of a country's real effective exchange rate as a measure of external competitiveness implicitly assumes that, in the long run, purchasing power parity prevails between the country and jts trading partners [Dombusch (1985)]. A testable définition of long run equilibrium existing among non-stationary time sériés is provided in the recently developed theory of cointegration [Engle and Granger (1987)], The paper extends earlier U.S. work in this are a by Layton and Stark (1990) by investigating the existence of such a long run 'statistical equilibrium' between measures of the Australian inflation rate and an effective exchange rate adjusted inflation rate computed from Australia's major trading partners

On the Real Exchange Rate as a Measure of Australia’s External Competitiveness

The use of a country’s real effective exchange rate as a measure of external competitiveness implicitly assumes that, in the long run, purchasing power parity prevails between the country and its trading partners [Dornbusch (1985)]. A testable definition of long run equilibrium existing among non-stationary time series is provided in the recently developed theory of cointegration [Engle and Granger (1987)]. The paper extends earlier U.S. work in this area by Layton and Stark (1990) by investigating the existence of such a long run ‘statistical equilibrium’ between measures of the Australian inflation rate and an effective exchange rate adjusted inflation rate computed from Australia’s major trading partners.

DO THE PHASES OF THE BUSINESS CYCLE DIE OF OLD AGE?

The paper re-examines the issue of duration dependence in the Australian classical and growth business cycles in light of the somewhat surprising results obtained recently by Cashin and Ouliaris (2004). In so doing the authors use the multinomial logit regime switching modelling approach of Layton and Smith (2003). The paper also represents an extension of the earlier work on the issue undertaken by Bodman (1998); the key extensions being that the issue is framed within an explicit established business cycle chronology, a leading index is also included within the analysis, and the growth cycle, in addition to the classical cycle, is considered. Strong evidence of duration dependence is found for periods of recession within the classical cycle and for both phases of the growth cycle. Moderate evidence of duration dependency is also found for periods of classical cycle expansion. However, the evidence in this regard is significantly reduced once movements in the leading index are included in the analysis with its movements exhibiting strong power in predicting the termination of classical business cycle expansions. For growth cycles, duration dependence symmetry is found across both phases of the cycle. Copyright Blackwell Publishing Ltd/University of Adelaide and Flinders University 2005..

Predicting quarterly Hong Kong tourism demand growth rates, directional changes and turning points with composite leading indicators

This study predicts numerical demand growth rates, directional changes and turning points in the growth rate using the single input leading indicator model and assesses its forecasting performance with the ARIMA model and the no-change model. To assess the forecasting performance from the March quarter of 2004 to the December quarter of 2006, models are fitted to the growth rates of Hong Kong inbound tourism demand from selected tourism markets (Australia, Japan, the UK and the USA). Composite leading indicators for the single input leading indicator model are constructed from selected national leading and lagged indicators. To avoid false signals in turning points, a method is specified to identify the correct turning points in tourism demand growth rates. The prediction performance of these models is then examined, based on the mean absolute percentage error, directional change error and turning point error. A statistical procedure is considered to determine whether the actual and predicted directional changes and turning points are independent or associated