Gain-loss measurements on a carbon-fibre composite reflector antenna

The loss of gain due to surface-current attenuation on an uncoated carbon-fibre-reinforced-plastics reflector antenna has been investigated by comparing an uncoated antenna with the same unit with the addition of a metallised surface. The measurements show that the gain loss of the test antenna is of the order of 0.5 dB at X band frequencies.     

Charge-splitting c.c.d. tapped delay lines

Two new types of c.c.d. tapped delay lines are described. One has parallel channels separated by channel stops from input to output. The other has channel stop wedges partitioning charge packets down the device. High performance is achieved.     

Esophageal squamous carcinoma

Squamous cell carcinoma of the esophagus is a tumor with poor prognosis; it is usually in an advanced state when first diagnosed. Because a multimodal treatment approach is currently used, proper tumor staging is essential to determine whether therapy should be directed toward cure or palliation. Important prognostic features of squamous cell carcinoma include the depth of tumor infiltration into or through the esophageal wall and the presence of distant metastases. Imaging strategies should not be limited to visualization of the tumor but also should be directed toward accurate pretreatment staging. In this article, the authors review the use of barium swallow, CT scans, and endoscopic ultrasonography both alone and in combination to visualize and stage esophageal carcinoma. The strengths and limitations of each modality are also discussed.     

Circadian variations of the urinary excretion of catecholamines and electrolytes

Concomitant measurements of circadian variations in the urinary excretion of dopamine (DA), homovanillic acid (HVA), norepinephrine (NE), epinephrine (E) as well as of creatinine, sodium and potassium under controlled dietary conditions during relative physical and emotional rest in 13 volunteers have shown that maximum excretion of all these substances occurred in the afternoon period between 14:30h and 18:00h, and minimum excretion in the morning between 4:00h and 5:00h. The changes were in some cases progressive from one collection period to the other, and synchronized for NE and E. DA and HVA excretions fluctuated from subject to subject. Excretory rhythms of sodium and potassium were found to be similar to those of the catecholamines. This can be explained by diurnal changes in renal blood flow and different renal excretory mechanisms of catecholamines. None of the catecholamines correlated with the urinary volume but urinary NE and E positively correlated with urinary creatinine, urinary NE and E with urinary DA and urinary sodium with urinary E. There are some common patterns in the diurnal rhythms of catecholamines and electrolytes but their interrelationship is different for individual catecholamines.     

Nonreciprocal representation of the floating inductor with grounded-amplifier realisations

The floating inductor is approximated to by the nonreciprocal transmission matrix (1, Ls; 1/R, 1), where L = CR2 with R sufficiently large and CR2 constant. Representations of this matrix are obtained by a form of synthesis procedure and are realised with only one type of grounded operational amplifier. Results are given which show their performance in a lowpass filter.     

Simple impedance transforming feed system for low-gain quadrifilarand bifilar satellite terminal antennas

An impedance transforming balun feeder system has been devised for low-gain antennas such as quadrifilar helices and spirals, consisting of four coaxial cables and a microstrip circuit. The arrangement allows physically orthogonal `balanced pair' outputs with quadrature phasing, in space limited configurations     

Patterns of current and lifetime substance use in schizophrenia

A structured interview and standardized rating scales were used to assess a sample of 194 outpatients with schizophrenia in a regional Australian mental health service for substance use, abuse, and dependence. Case manager assessments and urine drug screens were also used to determine substance use. Additional measurements included demographic information, history of criminal charges, symptom self-reports, personal hopefulness, and social support. The sample was predominantly male and showed relative instability in accommodations, and almost half had a history of criminal offenses, most frequently drug or alcohol related. The 6-month and lifetime prevalence of substance abuse or dependence was 26.8 and 59.8 percent, respectively, with alcohol, cannabis, and amphetamines being the most commonly abused substances. Current users of alcohol comprised 77.3 percent and current users of other nonprescribed substances (excluding tobacco and caffeine) comprised 29.9 percent of the sample. Rates of tobacco and caffeine consumption were high. There was a moderate degree of concordance between case manager determinations of a substance-use problem and research diagnoses. Subjects with current or lifetime diagnoses of substance abuse/dependence were predominantly young, single males with higher rates of criminal charges; however, there was no evidence of increased rates of suicide attempts, hospital admissions, or daily doses of antipsychotic drugs in these groups compared with subjects with no past or current diagnosis of substance abuse or dependence. Subjects with a current diagnosis of substance use were younger at first treatment and currently more symptomatic than those with no past or current substance use diagnosis. The picture emerging from this study replicates the high rate of substance abuse in persons with schizophrenia reported in North American studies but differs from the latter in finding a slightly different pattern of substances abused (i.e., absence of cocaine), reflecting relative differences in the availability of certain drugs.     

Evidence for coherent noise in pumped Schottky-diode mixers

Measurements of inherent mixer noise are reported, which indicate the existence of coherent-noise contributions at signal, image and intermediate frequencies. Comparisons with a resistive model for a pumped mixer reveal some agreement with experimental results, and could explain some anomalous noise phenomena.