Hybrid magnetic tunnel junction/vertical cavity surface emittinglaser field sensor device

A hybrid magneto-optoelectronic device is demonstrated, composed of a magnetic tunnel junction and a vertical cavity surface emitting diode laser. External magnetic field changes are translated into amplitude modulation of the laser output power with sensitivity that suggests applications in wireless and remote sensing of magnetic fields     

On generalized Erd?s spaces

During the last years both Erd?s space and complete Erd?s space were topologically characterized by Dijkstra and van Mill. Applications include results about Erd?s type spaces in ?p-spaces as well as results about Polishable ideals on ω. We present an unifying theorem in terms of sets with a reflexive relation that among other things contains these apparently dissimilar results as special cases.     

消除运算放大器的意外正反馈

由运算放大器构成的反馈系统常用于使系统保持稳定。但是在一些情况下也有意外发生。比如太阳能船的玩具,当有时打开开关时,玩具甚至会发出“噗噗”的声响。这种情况有可能是由于运算放大器发生了意外正反馈（inadvertent positive feedback）导致的。     

Prehomogeneous vector spaces and ergodic theory II

We apply M. Ratner's theorem on closures of unipotent orbits to the study of three families of prehomogeneous vector spaces. As a result, we prove analogues of the Oppenheim Conjecture for simultaneous approximation by values of certain alternating bilinear forms in an even number of variables and certain alternating trilinear forms in six and seven variables.

     

Growth and characterization of L‐alanine doped KDP crystals

Potassium Dihydrogen Phosphate (KDP) is an excellent inorganic nonlinear optical (NLO) material with different device applications. Most of amino acids possess NLO property; therefore, it is of interest to dope them in KDP crystals. In the present study, amino acid L‐alanine doped KDP crystals were grown by slow aqueous solvent evaporation technique. The doping of L‐alanine was confirmed by the paper chromatography, the CHN analysis and the FT‐IR spectroscopy. The powder XRD was carried out to assess the single phase nature of the samples. The effect of doping on thermal stability of the crystals was studied by TGA and the kinetic and thermodynamic parameters of dehydration were evaluated. As the amount of doping increased the thermal stability of crystals decreased. However, the second harmonic generation (SHG) efficiency and the UV‐Vis spectroscopy studies indicated that as the L‐alanine doping increased the SHG efficiency and optical transmission percentage increased. The dielectric behavior of the samples has been studied. The variation of dielectric constant, dielectric loss (tanδ), a.c.resistivity and a.c.conductivity with frequency of applied field in the range from 100 Hz to 100 kHz was studied. The dielectric constant and dielectric loss decreased with increase the value of frequency of applied field. The dielectric constant and the dielectric loss values of L‐alanine doped KDP crystals were lower than the pure KDP crystals. The results are discussed. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)