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Available from: Murat Akova, Oct 01, 2015
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    ABSTRACT: A differential phase shift circulator for C band has been developed using non-reciprocal transverse field ferrite elements of novel configuration. In this configuration the non-reciprocal phase shifters are constructed using ferrite toroids with a wire running axially inside the ferrite to magnetize it to remanence. This replaces the usual double ferrite slabs and external magnet. This configuration realizes two advantages. First, the magnetizing coil is inside the waveguide rather than outside and it is not necessary to propagate the switching pulse through the waveguide walls. Second, the ferrite toroids form a closed magnetic path. This allows the ferrite, once magnetized, to remain at remanence without having to maintain the magnetizing current. The circulator uses two 90deg differential phase shift sections (jayrators), a magic tee, and a short-slot hybrid coupler. The switching pulse is supplied by a line pulser which would supply current pulses of alternate polarity at the required current (30 amperes). The circulator operated over a frequency range of 4.9 KMc/ sec to 5.6 KMc/sec, with insertion loss of 1.3 db or less, and isolation of 20 db or more, at peak powers up to 550 KW, average power 100 to 200 watts. At higher peak powers sparking occurred, and at higher average powers heating was excessive and the performance seriously deteriorated. The device switched at all peak powers up to 550KW, in 20 nano seconds or less. The device thus offers, a combination of power handling capacity and switching speed not readily attainable by other microwave switches.
    IRE International Convention Record; 04/1964
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    ABSTRACT: This study aimed to determine the impact of blood stream infections (BSIs) on outcome of allogeneic hematopoietic SCT (HSCT), and to examine the influence of old (non-levofloxacin-containing) and new (levofloxacin-based) prophylactic antibiotic protocols on the pattern of BSIs. We retrospectively enrolled 246 allogeneic HSCT recipients between January 1999 and June 2006, dividing patients into BSI (within 6 months post-HSCT, n=61) and non-BSI groups (n=185). We found that Gram-negative bacteria (GNB) predominated BSI pathogens (54%). Multivariate analyses showed that patients with a BSI, compared with those without, had a significantly greater 6-month mortality (hazard ratio, 1.75; 95% confidence interval, 1.09-2.82; P=0.021) and a significantly increased length of hospital (LOH) stay (70.8 vs 55.2 days, P=0.014). Moreover, recipients of old and new protocols did not have a significantly different 6-month mortality and time-to-occurrence of BSIs. However, there were significantly more resistant GNB to third-generation cephalosporins and carbapenem in recipients of levofloxacin-based prophylaxis. Our data suggest that BSIs occur substantially and impact negatively on the outcome and LOH stay after allogeneic HSCT despite antibiotic prophylaxis. Levofloxacin-based prophylaxis, albeit providing similar efficacy to non-levofloxacin-containing regimens, may be associated with increased antimicrobial resistance.
    Bone marrow transplantation 11/2010; 46(9):1231-9. DOI:10.1038/bmt.2010.286 · 3.57 Impact Factor
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    ABSTRACT: Exercise or lack of it in early life affects chondro-osseous development. Two groups of horses were used to investigate the effects of age and exercise regimen on bone parameters of diaphyseal, metaphyseal, epiphyseal and cuboidal bones of the distal limb of Thoroughbreds. One group had exercised only spontaneously from an early age at pasture (PASTEX group), while the other group of horses were exposed to a 30% greater workload through additional defined exercise (CONDEX). Longitudinal data from peripheral quantitative computed tomography (pQCT) were obtained from eight scan sites of the left forelimb (proximal phalangeal (Pp; 1 site), third metacarpal (Mc3; six sites) and third carpal (C3; one site) bones) of 32 Thoroughbred foals scanned five times from ∼3 weeks to 17 months of age. The primary outcome measures were bone mineral content (BMC), bone area (BA), and periosteal circumference (Peri C) in diaphyseal bone, with cortical thickness (CortTh), volumetric bone mineral density (BMDv) and a bone strength index (SSI) also being analysed.
    The Veterinary Journal 12/2010; 190(3):383-9. DOI:10.1016/j.tvjl.2010.11.016 · 1.76 Impact Factor
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