Excited state absorption and stimulated emission of Nd3+ in crystals. Part 2: YVO4, GdVO4, and Sr5(PO4)3F

3+ ion in the crystals YVO₄, GdVO₄, and Sr₅(PO₄)₃F. The measurements were performed in the spectral region of the main laser transitions ⁴F_3/2→⁴I_9/2, ⁴F_3/2→⁴I_11/2, and ⁴F_3/2→⁴I_13/2by a continuous wave pump and probe technique. The calibrated gain and ESA spectra are presented and possible implications of ESA on the laser performance are estimated. It is shown that ESA can be a small loss factor to the laser emission near 1060 nm but does considerably diminish the effective emission cross sections near 1340 nm especially in Nd:YVO₄ and Nd:GdVO₄. Received: 29 January 1998/Revised version: 8 May 1998     

Spezialisierungen im reellen spektrum zu einer komplexen varietät

We study specializations in complex spectra of rings and give two applications to open mappings.     

Experiments with energetic μd and μt emitted from solid hydrogen

A set of experiments is reviewed which makes use of the emission of muonic deuterium from the surface of a layer of solid hydrogen. The behaviour of muons in a solid target system has been studied via detection of muon decay electrons, muonic X-rays, and fusion products (neutrons and charged particles). The emission of muonic deuterium is understood to result from the Ramsauer-Townsend scattering minimum. The energy distribution of the emitted atoms ranges from tenths of eV to about 10 eV, and can be controlled to some extent. A proposal is described to use muonic tritium emission to measure the energy dependence of muonic molecular formation.     

What Do Students Think Scientists Look Like?

The purpose of this study was to determine if there was a gender difference in the way nine to 12-year-old students drew scientists before and after their teachers implemented intervention strategies. Rubrics were used to analyze for stereotypic characteristics such as sex of the scientist and the presence of eye glasses, a lab coat, funny hair, a weird smile, wild eyes, facial hair, robotic features, and facial scars. Results indicated that boys held more stereotypic views on pretest drawings than did girls and also demonstrated the most improvement to less stereotypic views as a result of intervention.     

Portfolio selection with stable distributed returns

This paper analyzes and discusses the stable distributional approach in portfolio choice theory. We consider different hypotheses of portfolio selection with stable distributed returns and, more generally, with heavy-tailed distributed returns. In particular, we examine empirical differences among the optimal allocations obtained with the Gaussian and the stable non-Gaussian distributional assumption for the financial returns. Finally, we compare performances among stable multivariate models.     

Semi-empirical MNDO study of the structure of some diorganotin (IV) glycylglycinates

The geometrical structures of some diorganotin glycylglycinates have been obtained using the MNDO semi-empirical method. A good agreement with the experimental diffractometric data was found.     

Freezing Temperature in Dilute Ising Spin Glasses with Long-Range Interactions

The onset of spin-glass freezing in dilute Ising systems with long-range interactions is investigated with the use of numerical simulations. We show that taking pair correlations explicitly into account results in the renormalization of the interaction matrix and suppression of the density of localized states compared with conventional mean field theory. Application of the theory to the RKKY interaction in the dilute limit raises the question of the appropriate boundary eigenvalue of the effective interaction matrix that separates localized and extended states. We identify the onset of spin-glass freezing with the temperature T _g at which this boundary eigenvalue is equal to one. Numerical simulations reproduces the linear concentration dependence of T _g in the very dilute limit, in agreement with scaling relations, and show a significant improvement over the conventional mean-field theory in the value obtained for the freezing temperature.