Single-Lobe Single-Wavelength Lasing in Ultrabroad-Area Vertical-Cavity Surface-Emitting Lasers Based on the Integrated Filter Concept

We have studied broad-area vertical-cavity surface-emitting lasers grown in the antiwaveguiding approach (AVCSELs). The AVCSEL-type devices were fabricated in the ridge stripe geometry with openings in the top contact layer. Surface lasing was realized and evaluated for the devices with and without the integrated absorber section, acting as a selective filter for the emission modes propagating at finite tilt angle with respect to the normal to the surface (F-AVCSEL). It was found that the conventional AVCSEL device lases in high-order excited modes, tilted with respect to the normal to the surface, while lower order modes evolve at higher current densities causing a dramatic broadening of the emission spectrum. On the contrary, the F-AVCSEL emission is composed of a single spectral feature, which remains hardly affected up to the highest current densities >10 kA/cm². The far-field pattern is composed of a single zero-angle lobe with a beam divergence defined by the size of the opening in the top contact. No spectral features due to parasitic high-order modes were observed. The Gaussian-type single-wavelength surface-emitting lasing with an output power of 70 mW was realized in all-epitaxial wavelength-selective filter concept.     

Computational and experimental test of self starting regimes for the in-house needs of the PGU-450 steam-gas unit at the Kaliningrad TÉTs-2 Heating and Power Plant during supply disruptions

The major stages of a computational test of the self starting regimes for the in-house needs of unit No. 1 of the 450 MW steam-gas unit at the Kaliningrad TéTs-2 Heating and Electric Power Plant during supply disruptions are described. The results of an experimental test of five regimes are described and compared with the computational data. The results are analyzed. Recommendations are made for changes in the automatic reserve switching algorithms for the 6-kV sections, which, when realized, will ensure easier self startup for the mechanisms providing for in-house needs during supply disruptions. __________ Translated from élektricheskie Stantsii, No. 4, April 2008, pp. 46–55.     

Suppression of inward-rectifying K+ channels KAT1 and AKT2 by dominant negative point mutations in the KAT1 alpha-subunit

Na(+)-glucose transport and transepithelial permeability were investigated during symptomatic acute cryptosporidiosis in newborn rats. The infection resulted in a significant (P < 0.01) decrease in the ileal short-circuit current and a nonsignificant fall in the transepithelial potential difference and conductance. In glucose-stimulated conditions, the rise in ileal short-circuit current and transepithelial permeability were significantly lower in Cryptosporidium parvum-infected rats than in controls (delta Isc = 3.24 +/- 1.21 microA.cm-2 vs delta Isc = 5.09 +/- 2.23 microA.cm-2 in infected and control animals, respectively; P < 0.001; delta PD = -0.35 +/- 0.13 mV vs delta PD = -0.44 +/- 0.14 mV for infected and control animals, respectively; P < 0.01). Electrical parameters were not affected by addition of the cyclooxygenase inhibitor indomethacin in either Cryptosporidium-infected newborn rats or controls. Horseradish peroxidase and mannitol flux studies demonstrated a significant decrease (P < 0.05) in transepithelial molecular permeability in infected enterocyte rats, HRP flux = 380, range 68-5570 ng.cm-2, and mannitol flux = 1.06, range, 0.34-1.44%.cm-2.min-1, compared with controls rats, HRP flux = 4446 range, 1121-124,363 ng.cm-2, and mannitol flux = 1.99, range, 0.57-5.09%.cm-2.min-1; P < 0.05. These effects could originate from C. parvum-induced alteration of intracellular trafficking of pinocytosis vesicles and therefore account for the decrease in permeability to solute and macromolecules, together with impaired transcellular nutrient transport, in suckling rats.     

Solving linear and nonlinear three-dimensional problems of fracture mechanics by a semi-analytic finite element method. Part 1. Theoretical background and a study of efficiency of fem procedure for solving three-dimensional problems of fracture mechanics

We present theoretical approaches and a procedure for the FEM computation of parameters of nonlinear fracture mechanics in prismatic bodies with a crack. The efficiency of the proposed approaches and the veracity of the results obtained have been analyzed.     

Magnetic resonance imaging with implanted neurostimulators: an in vitro and in vivo study

OBJECTIVE: The goal was to assess the safety of magnetic resonance imaging (MRI) with implanted neurostimulators, in an in vitro and in vivo study. METHODS: Two different implantable pulse generators (IPGs) (ITREL II and 3; Medtronic, Minneapolis, MN) and different leads (separately and connected to an IPG) were tested in three different MRI scanners (0.2, 0.25, and 1.5 T). Measurements of the induced voltages (using an external oscilloscope) and the induced heat (using an infrared camera) were performed in an in vitro study. Finally, 38 patients with implanted neurostimulator systems (leads and IPGs) underwent MRI in 50 examinations, with continuous monitoring by a physician with uninterrupted visual and vocal contact with the patient. Twenty-five patients were studied prospectively, with documented printouts of the parameter settings before and after MRI. RESULTS: An induced voltage of 2.4 to 5.5 V was measured in the experimental configuration with a lead connected to an IPG. The voltage was higher with the leads alone, compared with the leads connected to the IPG, and was dependent on the MRI scanner, the sequences, and the type of lead. No heat induction was observed in any part of the hardware. No change of pulse shape or change of IPG parameters was observed during MRI. No adverse effects occurred in patients with chronically implanted deep brain leads connected to an IPG. CONCLUSION: MRI can be safely performed in patients with implanted neurostimulation systems with the tested deep brain leads connected to an IPG (ITREL II and 3), with running parameters. No heat induction was detected, and the experimentally measured induced voltage did not seem to harm the patients. Only the reed switch of the IPGs was activated; the other parameters remained unchanged. Further investigations must be performed to study the local electrical effects in larger plate electrodes; these effects might cause slight discomfort. There is no danger with any type of electrode during MRI examinations if the electrodes lie outside the region of interest. These observations are restricted to the tested devices. A conscientious estimation of the risks and benefits of MRI for patients with implanted devices is recommended. If the type of device is not known to the examiner, MRI should still be considered to be contraindicated.     

Granulocytic sarcoma presented as a reactivation of chronic myeloid leukemia after allogenic marrow transplantation

The authors report the case of a chronic myeloid leukemia (CML) patient submitted to allogenic bone marrow transplantation, who had probably never entered complete remission. The disease was reactivated as a granulocytic sarcoma, next to a platinum plate installed to correct a tibia fracture 11 years earlier. Its final event was a myeloid Ph1 + blastic crisis that was unsuccessfully treated with high doses of sc interferon and citarabine.