Robust phase-retrieval for quick whole-body SAR assessment using dual plane amplitude-only data

A robust phase-retrieval method with stable convergence and backpropagation properties for quick experimental whole body specific absorption rate (SAR) assessments is presented. A combination of a fast and coarse method and a more accurate gradient-based method is used to optimise the overall performance. To prevent the solution being trapped in a local minimum, several initial phase distributions are used. An accurate measurement procedure has been developed which reduces measurement time by roughly a factor of 2.5?4 at common mobile communication frequencies compared with a volume scan based procedure.     

Integrating reliability and timing analysis of CAN-based systems

This paper presents and illustrates a reliability analysis method developed with a focus on controller-area-network-based automotive systems. The method considers the effect of faults on schedulability analysis and its impact on the reliability estimation of the system, and attempts to integrate both to aid system developers. The authors illustrate the method by modeling a simple distributed antilock braking system, and showing that even in cases where the worst case analysis deems the system unschedulable, it may be proven to satisfy its timing requirements with a sufficiently high probability. From a reliability and cost perspective, this paper underlines the tradeoffs between timing guarantees, the level of hardware and software faults, and per-unit cost.     

60 GHz Single-Chip Front-End MMICs and Systems for Multi-Gb/s Wireless Communication

Single-chip 60 GHz transmitter (TX) and receiver (RX) MMICs have been designed and characterized in a 0.15mum (f_T~ 120 GHz/f _MAX> 200 GHz) GaAs mHEMT MMIC process. This paper describes the second generation of single-chip TX and RX MMICs together with work on packaging (e.g., flip-chip) and system measurements. Compared to the first generation of the designs in a commercial pHEMT technology, the MMICs presented in this paper show the same high level of integration but occupy smaller chip area and have higher gain and output power at only half the DC power consumption. The system operates with a LO signal in the range of 7-8 GHz. This LO signal is multiplied in an integrated multiply-by-eight (X8) LO multiplier chain, resulting in an IF center frequency of 2.5 GHz. Packaging and interconnects are discussed and as an alternative to wire bonding, flip-chip assembly tests are presented and discussed. System measurements are also described where bit error rate (BER) and eye diagrams are measured when the presented TX and RX MMICs transmits and receives a modulated signal. A data rate of 1.5 Gb/s with simple ASK modulation was achieved, restricted by the measurement setup rather than the TX and RX MMICs. These tests indicate that the presented MMICs are especially well suited for transmission and reception of wireless signals at data rates of several Gb/s     

The influence of defects on device performance of MBE-grown Si homojunction and strained Si1-xGex/Si heterostructures

Different Si homojunction and strained Si_1-xGe_x/Si heterojunction diodes and bipolar transistors have been fabricated by Si-MBE. The effect of annealing on Si homojunction diodes and transistors are studied. It is found that annealing generally improves the Si device performance, such as the ideality factor and breakdown characteristics. The influence of⁶⁰Co γ irradiation on the Si_1-xGe_x/Si diode performances are investigated by studying the temperature dependence of their electrical characteristics, and the results are correlated with the quality of the MBE-films. γ irradiation causes a drop in material conductivity due to the generation of atom-displacement defects in the whole volume of the wafers and increases the defect density at hetero-interfaces. The forward I-V curves of Si_1-xGe_x/Si devices may shift towards lower or higher voltages, depending on the film quality and the irradiation dose. The increase of defect density in strained Si_1-xGe_x/Si films appears to occur easier for the films with lower quality. Electrical measurements and calculations show that the defect-associated tunneling process is important in current transport for these MBE grown Si homojunction and strained Si_1-xGe_x/Si heterojunction devices, which have initially medium film quality or have been treated by irradiation.     

Stimulation of glycogenolysis by beta adrenergic agonists in skeletal muscle of mice with the phosphorylase kinase deficiency mutation (I strain)

The mechanism by which beta adrenergic agonist stimulate glycogenolysis in intact skeletal muscle was investigated in mice with the phosphorylase kinase deficiency mutation (I strain). Although extracts of I strain diaphragm muscle had only 3.7% of the phosphorylase kinase activity found in extracts of the control strain (C57BL), incubation of I strain hemidiaphragms in Krebs-Ringer bicarbonate buffer with either isoproterenol or epinephrine resulted in a stimulation of the rate of glycogenolysis. In C57BL diaphragms, the EC50 values for isoproterenol and epinephrine were 2 and 14 nM, respectively. With I strain diaphragms, dl-isoproterenol or l-epinephrine stimulated glycogenolysis as a linear function of the log of the drug concentration with no apparent plateau of response up to concentrations of 30 to 40 mugM. For each 10-fold increase in drug concentration, isoproterenol and epinephrine stimulated glycogenolysis in I strain muscles an additional 0.37 to 0.42 mg/g/hr, a slope in the concentration-response relationship of 0.17 and 0.37, respectively, of that measured in C57BL diaphragms at concentrations around the EC50. The highest glycogenolytic response measured in I strain hemidiaphragms (at 40 mugM isoproterenol) was 80% of the maximal catecholamine-stimulated glycogenolysis in C57BL diaphragms. Both 4 nM and 4 mugM isoproterenol, in a concentration-dependent manner, stimulated phosphorylase b to a conversion in I and C57BL diaphragms and increased cyclic adenosine 3':5'-monophosphate (cyclic AMP) concentrations. The glycogenolytic response to 10.1 nM dl-isoproterenol in both I and C57BL diaphragms was blocked by 34 nM l-propranolol but not by 34 nM d-propranolol. The response to 4 mugM isoproterenol was enhanced by the cyclic nucleotide phosphodiesterase inhibitors papaverine (27 mugM) or dl-4-(3-butoxy-4-methoxybenzyl)-2-imidazolidinone (Ro 20-1724, 3 mugM). From the results of these studies, we conclude: 1) Catecholamines stimulate glycogenolysis in skeletal muscle of I mice, as in C57BL mice, by interacting with the beta adrenergic receptor, thereby increasing tissue cyclic AMP concentrations and stimulating phosphorylase b to a conversion. 2) alternative hypotheses for the mechanism of the catecholamine-stimulated decrease in glycogen concentration in I skeletal muscle-inhibition of glycogen synthesis, hyposia and 5'-AMP stimulation of phosphorylase b activity-have been ruled out. 3) the activity of the mutant phosphorylase kinase, although it is only 3.7% of that in extracts of C57BL muscle, is sufficient to produce phosphorylase b to a conversion and thereby account for the glycogenolytic response of I strain muscle to catecholamines.     

Effects of hypoxia on the hemodynamic actions of prostaglandin E1

The effect of prostaglandin E1 (PGE1) on central and peripheral hemodynamics was studied in seven conscious dogs under conditions of normoxia and hypobaric hypoxia to ascertain if hypoxia attenuated the cardiovascular actions of PGE1. Silastic catheters were chronically implanted in the pulmonary artery, left atrium, and aorta. Acute hypoxia was produced in a hypobaric chamber maintained at 446 mmHg pressure (14,000 feet). PGE1 at sea level (normoxia) resulted in significant increases in heart rate, cardiac output, left ventricular stroke work and pulmonary blood volume as well as significant decreases in aortic, pulmonary arterial, and left atrial pressures. During hypobaric hypoxia, PGE1 produced essentially identical effects on all hemodynamic parameters except pulmonary blood volume and pulmonary arterial pressure where marked attenuation of PGE1 action occurred.     

Choroidal neovascular membrane in Best's vitelliform macular dystrophy

The right eye of a 9-year-old white boy with Best's vitelliform macular dystrophy had an intact egg-yolk lesion and a retinal pigment epithelial defect superiorly, suggesting an early pseudohypopyon stage. The disruptive phase of the left eye showed subretinal hemorrhages, a "signet ring," and a subretinal neovascular membrane.     

Transureteroureterostomy for urinary diversion in children

We report here a model of submaximal spinal cord injury, employing direct thoracic cord compression in ferrets. This yields consistent and reproducible long term consequences on local cellular structure and on locomotive function. We show also that both the anatomical and functional losses can be measured objectively using simple techniques, and that useful long-tract mediated locomotion is preserved after severe axonal losses at the site of injury.