A three dimensional finite element model of wind effects upon higher harmonics of the internal tide.

A non-linear three dimensional unstructured grid model of the M2 tide in the shelf edge area off the west coast of Scotland is used to examine the spatial distribution of the M2 internal tide and its higher harmonics in the region. In addition the spatial variability of the tidally induced turbulent kinetic energy and associated mixing in the area are considered. Initial calculations involve only tidal forcing, although subsequent calculations are performed with up-welling and down-welling favourable winds in order to examine how these influence the tidal distribution (particularly the higher harmonics) and mixing in the region. Both short and long duration winds are used in these calculations. Tidal calculations show that there is significant small scale spatial variability particularly in the higher harmonics of the internal tide in the region. In addition turbulence energy and mixing exhibit appreciable spatial variability in regions of rapidly changing topography, with increased mixing occurring above seamounts. Wind effects significantly change the distribution of the M2 internal tide and its higher harmonics, with appreciable differences found between up- and down-welling winds, and long and short duration winds due to differences in mixing and the presence of wind induced flows. The implications for model validation, particularly in terms of energy transfer to higher harmonics, and mixing are briefly discussed

Surface treatments for nickel and nickel-base alloys

Surface treatments of nickel and nickel alloys by diffusion coating, electroplating, explosive hardening, peening, and other method

A Bohmian approach to quantum fractals

A quantum fractal is a wavefunction with a real and an imaginary part continuous everywhere, but differentiable nowhere. This lack of differentiability has been used as an argument to deny the general validity of Bohmian mechanics (and other trajectory--based approaches) in providing a complete interpretation of quantum mechanics. Here, this assertion is overcome by means of a formal extension of Bohmian mechanics based on a limiting approach. Within this novel formulation, the particle dynamics is always satisfactorily described by a well defined equation of motion. In particular, in the case of guidance under quantum fractals, the corresponding trajectories will also be fractal.Comment: 19 pages, 3 figures (revised version

Reply to Comment by Galapon on 'Almost-periodic time observables for bound quantum systems'

In a recent paper [1] (also at http://lanl.arxiv.org/abs/0803.3721), I made several critical remarks on a 'Hermitian time operator' proposed by Galapon [2] (also at http://lanl.arxiv.org/abs/quant-ph/0111061). Galapon has correctly pointed out that remarks pertaining to 'denseness' of the commutator domain are wrong [3]. However, the other remarks still apply, and it is further noted that a given quantum system can be a member of this domain only at a set of times of total measure zero.Comment: 3 page

Blue frontiers: managing the environmental costs of aquaculture

The report begins with an overview of the current status of world aquaculture. It then goes on to describe an approach for estimating the current combined biophysical resource demands of aquaculture for producer countries and regions. Following a comparison of these results with those available for other animal food production sectors the report then examines the consequences of likely future trends in production on the environmental impacts of aquaculture. Finally, the policy implications of the report’s findings are discussed along with the research agenda that should be pursued to meet the challenge of sustainable food production

Semiclassical energy formulas for power-law and log potentials in quantum mechanics

We study a single particle which obeys non-relativistic quantum mechanics in R^N and has Hamiltonian H = -Delta + V(r), where V(r) = sgn(q)r^q. If N \geq 2, then q > -2, and if N = 1, then q > -1. The discrete eigenvalues E_{n\ell} may be represented exactly by the semiclassical expression E_{n\ell}(q) = min_{r>0}\{P_{n\ell}(q)^2/r^2+ V(r)}. The case q = 0 corresponds to V(r) = ln(r). By writing one power as a smooth transformation of another, and using envelope theory, it has earlier been proved that the P_{n\ell}(q) functions are monotone increasing. Recent refinements to the comparison theorem of QM in which comparison potentials can cross over, allow us to prove for n = 1 that Q(q)=Z(q)P(q) is monotone increasing, even though the factor Z(q)=(1+q/N)^{1/q} is monotone decreasing. Thus P(q) cannot increase too slowly. This result yields some sharper estimates for power-potential eigenvlaues at the bottom of each angular-momentum subspace.Comment: 20 pages, 5 figure

Ultraviolet downconverting phosphor for use with silicon CCD imagers

The properties and application of a UV downconverting phosphor (coronene) to silicon charge coupled devices are discussed. Measurements of the absorption spectrum have been extended to below 1000 A, and preliminary results indicate the existence of useful response to at least 584 A. The average conversion efficiency of coronene was measured to be ~20% at 2537 A. Imagery at 3650 A using a backside illuminated 800 X 800 CCD coated with coronene is presented