ΔT-window neutron spectrometer

A high resolution neutron spectrometer making use of a ΔT-window filter for the analyser and time-of-flight technique for analysing incident neutron energy has been designed. The spectrometer will provide a continuously variable energy resolution ΔE from 40-50μeV at ~ 5230μeV. The range of energy transfer allowed is -1450μeV to +2950μeV and the range of wavevector transferQ allowed is 0.82-3.06 Å-1. Depending on the resolution used, the counting rates are expected to vary from 28-60 × 103 counts/hr if one assumes 10% isotropic elastic scattering from the sample

Artificial Sequences and Complexity Measures

In this paper we exploit concepts of information theory to address the fundamental problem of identifying and defining the most suitable tools to extract, in a automatic and agnostic way, information from a generic string of characters. We introduce in particular a class of methods which use in a crucial way data compression techniques in order to define a measure of remoteness and distance between pairs of sequences of characters (e.g. texts) based on their relative information content. We also discuss in detail how specific features of data compression techniques could be used to introduce the notion of dictionary of a given sequence and of Artificial Text and we show how these new tools can be used for information extraction purposes. We point out the versatility and generality of our method that applies to any kind of corpora of character strings independently of the type of coding behind them. We consider as a case study linguistic motivated problems and we present results for automatic language recognition, authorship attribution and self consistent-classification.Comment: Revised version, with major changes, of previous "Data Compression approach to Information Extraction and Classification" by A. Baronchelli and V. Loreto. 15 pages; 5 figure

Hand osteoarthritis: clinical phenotypes, molecular mechanisms and disease management

Osteoarthritis (OA) is a highly prevalent condition and the hand is the most commonly affected site. Patients with hand OA frequently report symptoms of pain, functional limitations, and frustration in undertaking everyday activities. The condition presents clinically with changes to the bone, ligaments, cartilage and synovial tissue, which can be observed using radiography, ultrasonography or MRI. Hand OA is a heterogeneous disorder and is considered to be multifactorial in aetiology. This review provides an overview of the epidemiology, presentation and burden of hand OA, including an update on hand OA imaging (including the development of novel techniques), disease mechanisms and management. In particular, areas for which new evidence has substantially changed the way we understand, consider and treat hand OA are highlighted. For example, genetic studies, clinical trials and careful prospective imaging studies from the past 5 years are beginning to provide insights into the pathogenesis of hand OA that might uncover new therapeutic targets in disease

Dynamics of liquid silane

Neutron scattering of cold neutrons from liquid silane at 137°K and 98°K is explained on the basis of a simple model. The rotational diffusion constant,D r, and the delay time,τ 0, after which rotational diffusion may be said to occur are derived on the basis of this model. At 137°K we getD r=0.22×1013 sec-1 and τ 0=0.68× 10-13 sec. At 98°KD r (=0.06×1013 sec-1) is down by a factor of more than three butt 0=(0.54×10-13 sec) shows only a small change. By comparison with data on liquid CH4 it is concluded that the law of corresponding states is not applicable for describing rotational dynamics of CH4 and SiH4. Rotational motions in SiH4 are more hindered than in CH4 at the same reduced temperature

Experimental evidence of breakdown of simple pseudopotential theory for lattice dynamics of beryllium

We present dispersion curves for phonons along ΓKM in Be. It is shown that the ordering of the branches corresponding to the phonon modes polarized in the basal plane at the symmetry point K provides a simple and direct qualitative criterion for the presence of tensor forces. The existing pseudopotential calculations of the dynamics are inherently incapable of explaining these results. Generalizations required in the theory are mentioned

Frequency distribution function of solid ammonia

The frequency distribution function, g(ω), for solid ammonia has been derived from neutron inelastic scattering experiments at 106°K. It is used to calculate the specific heat and to analyse it in terms of Debye temperatures for translational and rotational parts. A comparison of the Debye temperatures with those obtained from the measured specific heat shows an excellent agreement up to 100°K, suggesting that the anharmonicity is not large below this temperature. Translational and rotational moments of the frequency distribution function calculated from the obtained g(ω) and the specific heat data are found to agree within about 10%

Lattice dynamics of beryllium

Phonon frequencies in beryllium along the principal symmetry directions have been determined by means of the slow neutron inelastic scattering technique. The data are analysed in terms of a six-neighbour force constant model and the force constants are evaluated. It is concluded that strong tensor forces are present in beryllium and the importance of this finding to basic theories of lattice dynamics is pointed out