Analysis of class I phosphoinositide 3-kinase autophosphorylation sites by mass spectrometry

This article describes the identification of the autophosphorylation sites of the G protein-sensitive class I phosphoinositide 3-kinase isoforms beta and gamma by mass spectrometry. Since discrimination and suppression effects prevented the immediate detection and sequencing of phosphopeptides in complex mixtures, a strategy was applied that involved (32)P-radiolabeling of the phosphoproteins, cleavage of the phosphoproteins with several proteases and/or cyanogen bromide, separation of the resulting peptide mixtures by micro-reversed-phase liquid chromatography, and mass spectrometric analysis of fractions containing phosphopeptides. As a result the primary autophosphorylation sites of phosphoinositide 3-kinase p110beta and p110gamma subunits could be unambiguously assigned to the C-terminal Ser 1070 and Ser 1101, respectively.     

Bounded point evaluations and cyclic polynomials on the spaces $$\hat F$$

LetF be aBK space withAK and denote the set of all formal power series with such that ε F for the sequence of coefficients of . We give a necessary and sufficient condition for a point to be a bounded point evaluation on , and for a polynomial to be cyclic in . As special cases, we obtain the results for the space ℓ _p (β) in [7]. Research of the authors supported under the research project #1232 of the Serbian Ministry of Sciences and Tecnology and, in the case of the second author, also by the DAAD foundation (German Academic Exchange Service), grant 911 103 102 8.     

Effects of Professional Singing Education on Vocal Vibrato—A Longitudinal Study

Vocal vibrato is regarded as one of the essential characteristics of voice quality in classical singing. Professional singers seem to develop vibrato automatically, without actively striving to acquire it. In this longitudinal investigation, the vocal vibrato of 22 singing students was examined at the beginning of and after 3 years of professional singing education. Subjects sang an ascending-descending triad pattern in slow tempo on vowel [a:] at a comfortable pitch level twice at soft (piano) and twice at medium (mezzoforte) loudness. The top note of the triad pattern was sustained for approximately 5s. The mean and the standard deviation (SD) of the vibrato rate were measured for this note. Results revealed that after 3 years of training, voices with vibrato slower than 5.2 Hz were found to have a faster vibrato, and voices with vibrato faster than 5.8 Hz were found to have a slower vibrato. Standard deviation of vibrato rate was higher in soft than in medium loudness, particularly before the education. Also high values of SD of vibrato rate, exceeding 0.65 Hz, had decreased after the education. These findings confirm that vibrato characteristics can be affected by singing education.     

MOVPE homoepitaxy of high-quality GaN: Crystal growth and devices

Epitaxial growth on GaN bulk single crystal substrates sets new standards in GaN material quality. The outstanding properties provide insights into fundamental material parameters (e.g. lattice constants, exciton binding energies, etc.) with a precision not obtainable from heteroepitaxial growth on sapphire or SiC. With metalorganic vapor phase epitaxy (MOVPE) we realized unstrained GaN layers with dislocation densities about six orders of magnitude lower than in heteroepitaxy. By the use of dry etching techniques for surface preparation, an important improvement of crystal quality is achieved. Those layers reveal an exceptional optical quality as determined by a reduction of the low-temperature photoluminescence (PL) linewidth from 5 meV to 0.1 meV and a reduced X-ray diffraction (XRD) rocking curve width from 400 to 20 arcsec. As a consequence of the narrow PL linewidths, new features as, e. g. a fivefold fine structure of the donor-bound exciton line at 3.471 eV was detected. Additionally, all three free excitons as well as their excited states are visible in PL at 2 K.

Dry etching techniques for surface preparation allow morphologies of the layers suitable for device applications. We report on InGaN/GaN multi-quantum-well (MQW)_ structures as well as GaN pn- and InGaN/GaN double heterostructure light emitting diodes (LEDs) on GaN bulk single crystal substrates. Those LEDs are twice as bright as their counterparts grown on sapphire. In addition they reveal an improved high power characteristics, which is attributed to an enhanced crystal quality and an increased p-doping.     

Bestimmung der orthogonalitätstreuen Permutationen euklidischer Räume

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