Stochastic geometric properties of scalar interfaces in turbulent jets

Experiments were conducted in which the behavior of scalar interfaces in turbulent jets was examined, using laser-induced fluorescence (LIF) techniques. The experiments were carried out in a high Schmidt number fluid (water), on the jet centerline, over a jet Reynolds number range of 1000<=Re<=24 000. Both two-dimensional scalar data, c(r,t) at fixed x/d, and one-dimensional scalar data, c(t) at fixed x/d and r/x, were analyzed using standard one- and two-dimensional fractal box-counting algorithms. Careful treatment was given to the handling of noise. Both long and short records as well as off-centerline measurements were also investigated. The important effect of threshold upon the results is discussed. No evidence was found of a constant (power-law) fractal dimension over the range of Reynolds numbers studied. On the other hand, the results are consistent with the computed behavior of a simple stochastic model of interface geometry

Reynolds number dependence of scalar fluctuations in a high Schmidt number turbulent jet

The scalar rms fluctuations in a turbulent jet were investigated experimentally, using high-resolution, laser-induced fluorescence techniques. The experiments were conducted in a high Schmidt number fluid (water), on the jet centerline, over a jet Reynolds number range of 30003000 or 6500

Measurements of scalar power spectra in high Schmidt number turbulent jets

We report on an experimental investigation of temporal, scalar power spectra of round, high Schmidt number (Sc ≃ 1.9 × 10^3), momentum-dominated turbulent jets, for jet Reynolds numbers in the range of 1.25 × 10^4 ≤ Re ≤ 7.2 × 10^4. At intermediate scales, we find a spectrum with a slope (logarithmic derivative) that increases in absolute value with Reynolds number, but remains less than 5/3 at the highest Reynolds number in our experiments. At the smallest scales, our spectra exhibit no k^(−1) power-law behaviour, but, rather, seem to be approximated by a log-normal function, over a range of scales exceeding a factor of 40, in some cases

Some consequences of the boundedness of scalar fluctuations

Values of the scalar field c(x,t), if initially bounded, will always be bounded by the limits set by the initial conditions. This observation permits the maximum variance ∼(c′^2) to be computed as a function of the mean value c. It is argued that this maximum should be expected in the limit of infinite Schmidt numbers (zero scalar species diffusivity). This suggests that c′/c on the axis of turbulent jets, for example, may not tend to a constant, i.e., independent of x/d, in the limit of very large Schmidt numbers. It also underscores a difficulty with the k^(−1) scalar spectrum proposed by Batchelor [J. Fluid Mech. 5, 113 (1959)]

The effects of a 12-week leisure centre-based, group exercise intervention for people moderately affected with multiple sclerosis: a randomized controlled pilot study

&lt;b&gt;Objective:&lt;/b&gt; To establish the effects of a 12-week, community-based group exercise intervention for people moderately affected with multiple sclerosis. &lt;b&gt;Design:&lt;/b&gt; Randomised controlled pilot trial. &lt;b&gt;Setting:&lt;/b&gt; Two community leisure centres. &lt;b&gt;Participants:&lt;/b&gt; Thirty-two participants with multiple sclerosis randomised into intervention or control groups. &lt;b&gt;Intervention:&lt;/b&gt; The intervention group received 12 weeks of twice weekly, 60-minute group exercise sessions, including mobility, balance and resistance exercises. The control group received usual care. &lt;b&gt;Main outcome measures:&lt;/b&gt; An assessor blinded to group allocation assessed participants at baseline, after eight weeks and after 12 weeks. The primary outcome measure was 25-foot (7.6 m) walk time, secondary outcomes assessed walking endurance, balance, physical function, leg strength, body mass index, activity levels, fatigue, anxiety and depression, quality of life and goal attainment. &lt;b&gt;Results:&lt;/b&gt; The intervention made no statistically significant difference to the results of participants’ 25-foot walk time. However the intervention led to many improvements. In the intervention group levels of physical activity improved statistically between baseline and week 8 (P &#60; 0.001) and baseline and week 12 (P = 0.005). Balance confidence results showed a significant difference between baseline and week 12 (P = 0.013). Good effect sizes were found for dynamic balance (d = 0.80), leg strength (d = 1.33), activity levels (d = 1.05) and perceived balance (d = 0.94). &lt;b&gt;Conclusion:&lt;/b&gt; The results of the study suggest that community-based group exercise classes are a feasible option for people moderately affected with multiple sclerosis, and offer benefits such as improved physical activity levels, balance and leg strength

Measurements of scalar power spectra in high Schmidt number turbulent jets

Single-point, jet-fluid concentration measurements obtained from high Schmidt number (Sc ≃ 1.9 x 10^3) turbulent jets permit an investigation of temporal scalar power spectra, for jet Reynolds numbers in the range of 1.25 ≤ Re x 10^(-4)≤ 7.2. At intermediate scales, we find a spectrum with a logarithmic derivative (slope) that is increasing with Reynolds number, in absolute value, but less than 5/3 at the highest Reynolds number in our experiments. At the smallest scales, our spectra exhibit no k^(-1) power-law behavior, possessing a log-normal region over a range of scales exceeding a factor of 40, in some cases

Decoherence Effects in Reactive Scattering

Decoherence effects on quantum and classical dynamics in reactive scattering are examined using a Caldeira-Leggett type model. Through a study of dynamics of the collinear H+H2 reaction and the transmission over simple one-dimensional barrier potentials, we show that decoherence leads to improved agreement between quantum and classical reaction and transmission probabilities, primarily by increasing the energy dispersion in a well defined way. Increased potential nonlinearity is seen to require larger decoherence in order to attain comparable quantum-classical agreement.Comment: 25 pages, 6 figures, to be published in J. Chem. Phy

Against Fiduciaryy Constitutionalism

A growing body of scholarship draws connections between fiduciary law and the Constitution. In much of this literature, the Constitution is described as a fiduciary instrument that establishes fiduciary duties, not least for the President of the United States. This Article examines and critiques the claims of fiduciary constitutionalism. Although a range of arguments are made in this literature, there are common failings. Some of these involve a literalistic misreading of the works of leading political philosophers (e.g., Plato and Locke). Other failings involve fiduciary law—mistakes about how to identify fiduciary relationships, about the content and enforcement of fiduciary duties, and about the relationship of fiduciary status to good faith. Still other failings sound in constitutional law—linguistic confusions and an impossible attempt to locate the genre of the Constitution in the categories of private fiduciary law. These criticisms suggest fundamental weaknesses in the new and increasingly influential attempt to develop fiduciary constitutionalism

Cooperation in agriculture, livestock marketing

The partial paralysis of the economic world today has thrust many new and strange problems upon the American farmer which require group action for solution. Such problems as deflation and inflation; banking reforms; international trade and credit readjustments; unequal tax burdens; national land use problems—these problems cannot be handled by the individual farmer. They require action by farmers as a group, or by the nation as a whole, for solution. But not all of the problems require group action.” Many of them must be handled on an individual farm basis. For instance— whether to rent more or less land, whether to raise more or less livestock, whether to feed this or that ration, how to handle this field and that field—these are individual farm management questions. They have been accentuated by the depression. And in the main they have to be dealt with by the individual farmer acting alone