Retrograde nontransseptal balloon mitral valvuloplasty: immediate results and intermediate long-term outcome in 441 cases--a multicenter experience

OBJECTIVES: Our aim was to present the immediate and intermediate long-term results of the application of retrograde nontransseptal balloon mitral valvuloplasty (RNBMV) in four cooperating centers from Greece and India. BACKGROUND: RNBMV is a purely transarterial method of balloon valvuloplasty, developed with the aim to avoid complications associated with transseptal catheterization. Only single-center experience with RNBMV has been previously reported. METHODS: The procedure was attempted in 441 patients with symptomatic mitral stenosis (320 women, 121 men, mean age [+/-SD] 44+/-11 years, mean echocardiographic score [+/-SD] 7.7+/-2.0) from 1988 to 1996. Three hundred eighty-five patients with successful immediate outcome were followed clinically for a mean [+/-SD] of 3.5+/-1.9 (range, 0.5-9.1) years. RESULTS: A technically successful procedure was achieved in 388 (88%) cases. The echocardiographic score (p < 0.001), male gender (p=0.005), preprocedural mitral regurgitation (p=0.007) and previous surgical commissurotomy (p=0.029) were unfavorable predictors of immediate outcome. Complications included death (0.2%), severe mitral regurgitation (3.4%) and injury of the femoral artery (1.1%). Event-free (freedom from cardiac death, mitral valve surgery, repeat valvuloplasty and NYHA class > II symptoms) survival rates (+/-SEM) were 100%, 96.9+/-0.9%, 89.8+/-1.9% and 75.5+/-5.5% at 1, 2, 4 and 9 years, respectively. The echocardiographic score (p < 0.001), NYHA class (p=0.008) and postprocedural mitral valve area (p=0.009) were significant independent predictors of intermediate long-term outcome. CONCLUSIONS: Multicenter experience indicates that RNBMV is a safe and effective technique for the treatment of symptomatic mitral stenosis. As with the transseptal approach, patients with favorable mitral valve anatomy derive the greatest immediate and intermediate long-term benefit from this procedure.     

Cell searching in WCDMA

In Europe, the digital second generation (2G) systems, IS-136 and the Global System for Mobile communications (GSM), developed were based on time division multiple access (TDMA) and in the US, the IS-95 system developed was based on code division multiple access (CDMA). The 2G technologies developed both in Europe and US suffered from a number of limitations that included: low bit rate for 2G systems and non-interoperability between the standards. The low bit rate for 2G systems could not meet subscriber demands for new and faster non-voice services while on the move. Hence, the third generation (3G) systems were developed with the aim to solve these problems by promising global roaming across 3G standards, as well as support for multimedia applications. These 3G services are based on CDMA.     

Column Generation Based Heuristic Algorithm for Multi-Item Scheduling

The column generation algorithm for the multi-item lot-size scheduling problem under resource constraints is examined and improved upon by augmenting simpler heuristic routines in place of the time-consuming Wagner-Whitin dynamic programming routine. The heuristic algorithms thus developed are tested by controlling problem size, setup time, demand variability, and capacity change costs in test problems. The empirical results indicate that the proposed heuristic algorithms reduce CPU time as well as the number of iterations with only a slight loss in optimality.     

Electrical properties of Se1−xTex crystals

Single crystals of Se_1?xTe_x (with x varying from 0.1 to 0.9) were successfully grown by the Bridgman method. D.C. Hall effect and temperature dependence of π of these crystals were measured. π at 300°K is found to decrease and the carrier concentration to increase approximately exponentially with x. The temperature dependence of π shows that the conduction is thermally activated. At low temperature (< 300 °K) extrinsic conduction is dominant with the value of the activation energy decreasing from 0.065 to 0.006 eV as x increases from 0.1 to 0.9. At higher temperature, intrinsic conduction is observed for alloys with x = 0.4, 0.5, 0.6 and 0.8 yielding the values of intrinsic band gaps (E_g). The values of E_g are found to decrease with x.     

Avoided crossing of rattler modes in thermoelectric materials

Engineering of materials with specific physical properties has recently focused on the effect of nano-sized 'guest domains' in a 'host matrix' that enable tuning of electrical, mechanical, photo-optical or thermal properties. A low thermal conductivity is a prerequisite for obtaining effective thermoelectric materials, and the challenge is to limit the conduction of heat by phonons, without simultaneously reducing the charge transport. This is named the 'phonon glass-electron crystal' concept and may be realized in host-guest systems. The guest entities are believed to have independent oscillations, so-called rattler modes, which scatter the acoustic phonons and reduce the thermal conductivity. We have investigated the phonon dispersion relation in the phonon glass-electron crystal material Ba(8)Ga(16)Ge(30) using neutron triple-axis spectroscopy. The results disclose unambiguously the theoretically predicted avoided crossing of the rattler modes and the acoustic-phonon branches. The observed phonon lifetimes are longer than expected, and a new explanation for the low kappa(L) is provided.     

Structure and superconductivity of Gex Cu1−x alloy films

Structural studies of Ge_x - Cu_1?x alloy films show that for x >0.80 300 K deposited films are found to be amorphous. On in situ heating these samples to ～ 100°C, a discrete, crystalline, second phase particles of Cu₃ Ge (?) compound appear in the amorphous matrix of Ge. For x ? 0.8 crystallites of Cu₃ Ge can be detected in amorphous Ge at room temperature. At higher Cu concentration (x < 0.4) in addition to crystalline Cu₃ Ge and Ge, free copper is detected. These structural studies suggest that the superconductivity behavior observed in the quenched alloy films presumably arise from small crystallites of Cu₃ Ge embedded in the amorphous matrix of Ge.     

Isolation of two turkey influenza A viruses in Minnesota

Two influenza viruses were isolated from turkeys in 1973. A/Turkey/Minn/PR/73 was isolated from a flock with a 75% mortality. Antigenically its hemagglutinin was not similar to that of A/Turkey/Wis/66 virus. A/Turkey/Minn/Kandi/73 was recovered from a flock with 67% mortality. This isolant was antigenically similar to A/Turkey/Wis/66.     

Fabrication, RE performance, and yield of a combined limitingamplifier and dual-modulus prescalar GaAs IC chip

Production technology details, RF performance, and yield results for an ECL-compatible, L-band, limiting dual-modulus (÷10/11) prescalar are presented. Monolithic integration of analog and digital circuit functions is achieved using refractory self-aligned-gate FET technology. When tested with -22-dBm input signal power, one lot of six wafers had a total RF chip yield of 19% with a best-wafer yield of 43%. The average operating frequency was 1.45 GHz (SD=51 MHz) with an average power dissipation of 696 mW (SD=23 mW)     

Editorial

Mobile Networks and Applications -