Experimental Procedure for the Determination of the Number of Paramagnetic Centers

The determination of the number of paramagnetic centers in a given crystal is usually performed by comparing the resonance signal of the unknown centers with that of a calibrated standard. The two most often used standards are CuSO4·5H2O and DPPH. In the procedure described below the number of "spins" is obtained from a measurement of the reflection coefficient of a reflection cavity containing the spins; or more specifically from the change in the reflection coefficient between the "on resonance" and "off resonance" conditions. The measurements can be performed with the aid of the conventional equipment for the measurement of reflection coefficients. Great simplification is realized when a variable coupling cavity [1] is used

The laser

This article is intended as a review of the field of optical masers, or lasers as they have come to be known, summarizing both theory and practice. It starts with a theoretical section in which black body radiation theory is used to introduce the concepts of spontaneous and induced transitions. This is followed by the derivation of the Schawlow-Townes instability (start-oscillation) condition and a description of the different laser media. Other topics treated include: optical pumping, experimental techniques, output power and noise. The sections on optical resonators and communications which conclude the paper have been slightly emphasized since, perhaps to a larger extent than the other topics covered in this paper, they coincide with traditional areas of interest of microwave and communications engineers

Regulatory practice in the European telecommunications sector: Normative justification and practical application

The telecommunications sector is characterized by economies of scale and scope, high sunk costs, and strong network effects. This combination may facilitate monopolization and abuse of market power. The present study evaluates the need for sector-specific regulation in this sector. It is shown that there is a conflict between static and dynamic efficiency goals. A comparison of two prominent regulatory approaches for the telecommunications sector shows that the disaggregated approach takes account of this conflict most adequately, as it is committed to minimal regulation. The European regulatory framework for electronic communications markets is based on economic theory, and could principally be used to limit regulation to network areas in which stable networkspecific market power is localized. However, especially the criteria for the assessment of significant market power (SMP) are applied too liberally, such that, in practice, overregulation has resulted. --

Monetarist Interpretations of the Great Depression: An Evaluation and Critique

This paper rejects the proposition that there is only a single interesting question to ask about the decade of the 1930s. It is concerned not only with the role of money in the 1929-33 contraction but also with the relative role of monetary and nonmonetary factors in the recession of 1937-38 and subsequent recovery and, in addition, with the division of nominal income change between prices and real output. New empirical evidence bearing on each of these issues is provided The results suggest that both extreme monetarist and nonmonetarist interpretations of the decade of the l930s are unsatisfactory and leave interesting features of the data unexplained. Arguing against acceptance of an extreme monetarist interpretation are (1) the inability of changes in the money supply alone to explain the severity of the initial collapse in income between 1929 and the fall of 1931, (2) the steady weakening of the correlation between changes in nominal income and money as the 1930s progressed, (3) the failure of monetary factors to explain the nature and timing of the 1938-41 recovery, and (4) the apparent absence of any tendency for the mechanism of price flexibility to provide strong self-correcting forces as required by an approach that stresses monetary rules and opposes policy activism. Arguing against acceptance of an extreme nonmonetarist interpretation are (1) the close association between the collapse in income and the lagged effect of monetary changes after the fall of 1931, (2) the milder contraction and earlier recoveries associated with the more expansive monetary policies pursued in Europe, (3) the close association between money and income in the 1937-38 recession, and (4) the failure of the price change data to adhere to the expectational Phillips curve approach imbedded in many postwar econometric models constructed by nonmonetarists.

Being well, being musical: Music composition as a resource and occupation for older people

Introduction: Participatory music making for older people has tended to focus on singing and performance. In a community music project undertaken by Manchester Camerata (a chamber orchestra), Blacon Community Trust and a small group of older adults, participants were given the opportunity to compose individual pieces of music interactively with professional musicians. This paper reports the findings of the research project. Method: An arts-based research method was adopted and incorporated action research and interpretive interactionism to articulate the experiences and perceptions of participants. Participants and Manchester Camerata musicians also worked together to represent the thematic findings of the research in a group composition. Findings: The findings demonstrate that individual and group music composition contributed to a sense of wellbeing through control over musical materials, opportunities for creativity and identity making, validation of life experience and social engagement with other participants and professional musicians. Conclusion: The results emphasised occupation as essential to health and wellbeing in the later stages of life. The findings also highlight the particularly innovative aspects of this research: (i) the use of music composition as a viable arts-in-health occupation for older people and (ii) the arts-based research method of group composition

Finite size scaling of the bayesian perceptron

We study numerically the properties of the bayesian perceptron through a gradient descent on the optimal cost function. The theoretical distribution of stabilities is deduced. It predicts that the optimal generalizer lies close to the boundary of the space of (error-free) solutions. The numerical simulations are in good agreement with the theoretical distribution. The extrapolation of the generalization error to infinite input space size agrees with the theoretical results. Finite size corrections are negative and exhibit two different scaling regimes, depending on the training set size. The variance of the generalization error vanishes for $N \rightarrow \infty$ confirming the property of self-averaging.Comment: RevTeX, 7 pages, 7 figures, submitted to Phys. Rev.

Landau levels and the Thomas-Fermi structure of rapidly rotating Bose-Einstein condensates

We show that, within mean-field theory, the density profile of a rapidly rotating harmonically trapped Bose-Einstein condensate is of the Thomas-Fermi form as long as the number of vortices is much larger than unity. Two forms of the condensate wave function are explored: i) the lowest Landau level (LLL) wave function with a regular lattice of vortices multiplied by a slowly varying envelope function, which gives rise to components in higher Landau levels; ii) the LLL wave function with a nonuniform vortex lattice. From variational calculations we find it most favorable energetically to retain the LLL form of the wave function but to allow the vortices to deviate slightly from a regular lattice. The predicted distortions of the lattice are small, but in accord with recent measurements at lower rates of rotation.Comment: 4 pages, 2 figures, to appear in Phys. Rev. Lett. (extend the arguments of cond-mat/0402167