Transforming transformers [superconducting windings]

Use of high-temperature superconducting (HTS) windings may soon turn power transformers into compact high-performers on good terms with the environment. The potential for HTS transformers is being examined in major design and hardware development programs by several teams of engineers and scientists worldwide. The team to which the authors belong is led by Waukesha Electric Systems. The Waukesha-led team has conducted a series of reference designs concentrating mostly on a 30-MVA, 138-kV/13.8-kV transformer rating. This rating is representative of a medium power transformer class foreseen as comprising about half of all US power transformer sales in the next two decades. Two of these designed are compared with a 30-MVA conventional oil-filled transformer typical of this class. Each uses a different commercially successful and reliable type of refrigeration. Since reliable operation is paramount, both transformers are designed to have a several-day on-board refrigeration reserve that lets them operate continuously with no interruption of service to customers     

Allogeneic matched T-cell-depleted bone marrow transplantation for acute leukemia patients

It has been shown that high doses of human recombinant erythropoietin (r epo) increase haemoglobin levels by augmentation of F-cells, and Hb-F production in animal models and in human trials. In this study, r epo was used in patients with beta thalassemia intermedia. Our purpose was to improve haemoglobin levels by at least 2 g and maintain an average level between 10 and 12 g/dl. Ten patients aged 6-29 years (mean 14 +/- 7.6 years) with thalassemia intermedia were treated with r epo. It was given subcutaneously in rising doses from 500 to 1000 U/kg three times weekly for 3 months. During r epo therapy eight cases (80 per cent) showed an increase in haemoglobin, haematocrit, and reticulocyte levels, and an increase of at least 2 g of haemoglobin was obtained. Blood transfusion was not needed during the study except in one case. Five cases (50 per cent) improved life quality with therapy. Hb levels of all patients returned to baseline values over 1 or 2 months after r epo was discontinued. There was no significant change in absolute Hb-F, F-cells, and ferritin levels during treatment. Generally, the drug was well tolerated. No patient had hypertension. Recombinant erythropoietin seems to be an effective treatment for anaemia of beta-thalassemia intermedia, but longer term randomized trials are needed especially in patients with beta thalassemia major.     

Unrelated donor marrow transplantation for chronic myelogenous leukaemia

Between January 1989 and July 1995 the search for an unrelated donor (UD) was started for 379 consecutive Italian patients with Philadelphia positive (Ph+) chronic myelogenous leukaemia (CML). 89 (23%) were transplanted. The overall probability of transplant before and after December 1991 was 16% and 49%, respectively (P=0.0001), and average interval between search activation and graft was 23 months and 13 months, respectively (P=0.0001). Disease-free survival (DFS) following 60 consecutive transplants performed before February 1996 was 41.5% at 48 months and was 64% for patients grafted after January 1993. In univariate analysis, five variables had a favourable effect on DFS: year of bone marrow transplantation (BMT) after 1993 (P=0.0002), HLA-DRB1 donor/recipient (D/R) match (P=0.0006), total body irradiation (TBI) containing regimen (P=0.0006), graft-versus-host disease (GvHD) prophylaxis including 'early' cyclosporin before the transplant, and a marrow cell dose > 3 x 10(8)/kg of recipient body weight (P=0.04). Multivariate analysis confirmed that HLA identity (P=0.006), TBI-containing regimen (P=0.0001) and 'early cyclosporin' (P=0.04) were associated with higher DFS. Transplant-related mortality (TRM) was 67% in patients grafted before January 1993 and 30% in patients grafted subsequently (P=0.002). Multivariate analysis confirmed DRB1 identity (P=0.03) and TBI-containing regimen (P=0.0005) to be independent factors predictive of low TRM. This suggests that the outcome of patients transplanted from an HLA DRB1 matched donor, after a TBI-containing preparative regimen, is similar to results recently reported in patients transplanted from geno-identical siblings. These results indicate that the search should be initiated at diagnosis for patients < 45 years of age and UD BMT should be considered early in the disease course for those with an available DRB1-matched unrelated donor.     

Arrays of InP-based Avalanche Photodiodes for Photon Counting

Arrays of InP-based avalanche photodiodes (APDs) with InGaAsP absorber regions have been fabricated and characterized in the Geiger mode for photon-counting applications. Measurements of APDs with InGaAsP absorbers optimized for 1.06 mum wavelength show dark count rates (DCRs) <20 kHz for room-temperature operation with photon detection efficiency (PDE) up to 50% and a reset or dead time of 1s. APDs with InGaAs absorbers optimized for 1.55 mum wavelength and 240 K temperature have DCRs <20 kHz, PDE up to 45%, and a reset time of ~6 mus. Arrays for both wavelengths have been fabricated and packaged with GaP microlenses (of 100 and 50 mum pitch) and CMOS readout integrated circuits (ROICs). Comparisons are made between ROICs that operate in the framed-readout mode as well as those that operate in continuous-readout mode.     

MAGDA: A Mobile Agent based Grid Architecture

Mobile agents mean both a technology and a programming paradigm. They allow for a flexible approach which can alleviate a number of issues present in distributed and Grid-based systems, by means of features such as migration, cloning, messaging and other provided mechanisms. In this paper we describe an architecture (MAGDA – Mobile Agent based Grid Architecture) we have designed and we are currently developing to support programming and execution of mobile agent based application upon Grid systems.