Magneto-optical stokes polarimetry and nanostructured magnetic materials.

Stokes parameters fully characterize the polarization state of light in an experimentally accessible manner. Photoelastic modulator (PEM) based Stokes polarimetry offers a very high sensitivity which is particularly suitable for the investigation of the magneto-optical properties of nanostructured magnetic materials. In this paper, we shall describe a robust methodology recently developed by us that utilizes a dual PEM setup. As an example of its application, we report on the magneto-optical characteristics of focused Ga ion beam patterned Fe films. We have investigated Ga ion irradiation of single-layer polycrystalline Fe films deposited on Si3N4 substrates, which allows us to study the effects of ion implantation with minimum added complications. Complemented by structural and other characterization techniques, the absolute measurement of magneto-optical effects through the determination of Stokes parameters has enabled us to effectively separate the various contributions from film thinning due to sputtering, structural modifications and compositional changes caused by Ga incorporation. A comparison is also made between the magneto-optical behavior of patterned thin films and that of anodic aluminum oxide embedded magnetic nanowire arrays.

Age of the floor of the eastern Indian ocean.

Deep sea drilling in the eastern Indian Ocean shows that the oceanic crust off Western Australia is approximately 140 million years old and becomes younger to the west; this dates the initial opening of the Indian Ocean.

Chlamydia pneumoniae antibodies in severe essential hypertension.

Several studies have implied an association between Chlamydia pneumoniae (C. pneumoniae) and cardiovascular disease. Our study was designed to determine whether this organism is associated with severe essential hypertension in a multiracial British population. Antibodies to C. pneumoniae were measured by microimmunofluorescence in 123 patients with chronic severe hypertension and 123 control subjects, matched for ethnic origin, age, sex, and smoking habit, admitted to the same hospital with various noncardiovascular, nonpulmonary disorders. Previous infection was defined by IgG 64 to 256, provided that there was no detectable IgM. Multiple regression analyses of matched and unmatched data were used to investigate the influences of antibody levels and potential confounding factors (ethnic origin, age, sex, smoking habit, diabetes mellitus, and social deprivation) on hypertension. A portion of the hypertensive patients underwent echocardiography, estimation of left ventricular mass index, and measurements of fibrinogen, D-dimer, and von Willebrand factor concentrations. Thirty-five percent of hypertensive patients and 17.9% of matched control subjects had antibody titers consistent with previous C. pneumoniae infection. The hypertensive patients differed significantly from their matched control subjects in their level of previous infection, with an odds ratio of 2.5 (95% confidence interval, 1.3 to 4.7). There were no significant differences in antibody levels between patients with left ventricular hypertrophy and those without it. Fibrinogen, D-dimer, and von Willebrand factor concentrations were not significantly associated with antibody levels. These data support an association of C. pneumoniae with severe essential hypertension. They provide no evidence of a predisposition to develop left ventricular hypertrophy in hypertensive patients with C. pneumoniae infection or of associations with hypercoagulability or endothelial dysfunction.

Muscarinic agonist receptor subtypes in aging rat brain.

Whole brain homogenates from rats aged 6 months (young) and 24 months (old) showed a decline with age of the pre-synaptic cholinergic marker, choline acetyltransferase, and also of total specific binding sites for the muscarinic antagonist L(-)quinuclidinyl benzilate (L-QNB). However, neither the proportion nor the inhibition constants of high and low affinity muscarinic agonist binding sites (defined by displacement of L-QNB binding with carbachol) changed with age. These findings may be relevant to the central cholinergic deficit reported to be associated with cognitive impairment in aging man.

Infectious agents and atherosclerotic vascular disease.

The pathological changes underlying occlusive vascular disease show considerable overlap with those caused by a range of infections. Particular viral and bacterial pathogens have long been suspected of playing a part, directly or indirectly, in the process leading to atherosclerosis. We review recent evidence of links between infections and ischaemic heart disease, particularly in the case of Chlamydia pneumoniae infection. Possible mechanisms for these associations are discussed.

Drinking and schooling.

We employ the National Longitudinal Survey of Youth data to explore the effect of youthful drinking on years of schooling and on the likelihood of college graduation. Our instruments for youthful drinking include the state beer tax and the minimum purchase age. Reduced form equations are also estimated. Our results indicate that heavy drinking in high school reduces the average number of years of schooling completed following high school. Other things equal, students who spend their high school years in states with relatively high taxes and minimum age are more likely to graduate from college.

The effects of short-term variation in abortion funding on pregnancy outcomes.

The appropriations for North Carolina's abortion fund have proven inadequate during five of the years between 1980 and 1994. This on-again, off-again funding pattern provides a natural experiment for estimating the short-run effect of changes in the cost of abortions on the number of abortions to indigent women. Using an unusually detailed dataset, we estimate the effects of funding termination on the monthly abortion and birth rates. Overall, approximately one-third of pregnancies that would have resulted in an abortion, had state funds been available, are instead carried to term.

Purulent and constrictive pericarditis arising from a staphylococcal lumbar infection.

A 78-year-old man was admitted to the hospital for evaluation and treatment of anasarca secondary to staphylococcal purulent pericarditis. One month earlier he had undergone a lumbar laminectomy that was complicated postoperatively by a lumbar abscess that was not clinically apparent. The infection subsequently spread to the pericardium. Despite aggressive therapy that included therapeutic pericardiocentesis, drainage of pericardial fluid, and prolonged intravenous antibiotic therapy, the patient returned 2 weeks after discharge from the hospital with complicating constrictive pericarditis. Pericardiectomy was performed, resulting in complete relief of the patient's symptoms.

Inverse and predictive modeling of seepage into underground openings.

We discuss the development and calibration of a model for predicting seepage into underground openings. Seepage is a key factor affecting the performance of the potential nuclear-waste repository at Yucca Mountain, Nevada. Three-dimensional numerical models were developed to simulate field tests in which water was released from boreholes above excavated niches. Data from air-injection tests were geostatistically analyzed to infer the heterogeneous structure of the fracture permeability field. The heterogeneous continuum model was then calibrated against the measured amount of water that seeped into the opening. This approach resulted in the estimation of model-related, seepage-specific parameters on the scale of interest. The ability of the calibrated model to predict seepage was examined by comparing calculated with measured seepage rates from additional experiments conducted in different portions of the fracture network. We conclude that an effective capillary strength parameter is suitable to characterize seepage-related features and processes for use in a prediction model of average seepage into potential waste-emplacement drifts.

Measurement system for systematic hydrological characterization of unsaturated fractured welded tuff in a mined underground tunnel.

A field investigation of unsaturated flow through a lithophysal unit of fractured welded tuff containing lithophysal cavities has been initiated. To characterize flow in this spatially heterogeneous medium, a systematic approach has been developed to perform tests in boreholes drilled at regular intervals in an underground tunnel (drift). The purpose of the testing is to quantify the amounts of water seeping into the drift versus the amount of water moving around the drift when released into boreholes at many equidistant locations along the drift. In this paper, we describe the test equipment system that has been built for this purpose. Because the field-scale measurements--of liquid flow in the unsaturated, fractured rocks--require continuous testing for periods of days to weeks, the control of test equipment has been fully automated, allowing operation with no human presence at the field site. Preliminary results from the first set of tests indicate that, while the effects of evaporation on characterization of hydrological properties of the rock can be significant, these effects can be controlled and quantified. These tests give insight into the role of the cavities as potential storage during the initial transient flow prior to the breakthrough of water at the drift crown, as well as the role of connected fractures that provide the subsequent quasi-steady flow. In addition to the stated purpose of realizing the flow partitioning, the results yield values for the effective porosity in the pathways for liquid flow in the regions tested thus far.

Aspergillus clavatus tremorgenic neurotoxicosis in cattle fed sprouted grains.

Beef and dairy cattle from four different herds in southern and central Queensland fed hydroponically-produced sprouted barley or wheat grain heavily infested with Aspergillus clavatus developed posterior ataxia with knuckling of fetlocks, muscular tremors and recumbency, but maintained appetite. A few animals variously had reduced milk production, hyperaesthesia, drooling of saliva, hypermetria of hind limbs or muscle spasms. Degeneration of large neurones was seen in the brain stem and spinal cord grey matter. The syndrome was consistent with A clavatus tremorgenic mycotoxicosis of ruminants. The cases are the earliest known to be associated with this fungus in Australia. They highlight a potential hazard of hydroponic fodder production systems, which appear to favour A clavatus growth on sprouted grain, exacerbated in some cases by equipment malfunctions that increase operating temperatures.

Clinical aspects of Chlamydia pneumoniae infection.

This recently recognised member of the genus Chlamydia is one of the most widespread pathogens of man, though up to 90% of infected people have few or no symptoms. Several studies have estimated the population prevalence of antibodies to C. pneumoniae at 40-55% in the northern hemisphere, and over 60% in under-developed countries. The incidence of infections follows a cyclical pattern, with peaks at regular intervals of 2-10 years, but no apparent seasonal periodicity. Nosocomial transmission may be mediated by environmental surfaces as well as aerosols, and immunosuppression, for example by the human immunodeficiency virus, predisposes to infection. Chlamydia pneumoniae causes predominantly atypical pneumonia, often severe in adults, especially the elderly; including 5-10% of community-acquired pneumonia in Scandinavian countries. Serological evidence indicates associations with asthma, bronchitis, exacerbations of chronic airflow obstruction, otitis media and bronchiolitis. Several studies, using both serological and morbid anatomical techniques, also indicate associations with vascular atheroma and ischaemic heart disease, and with acute myocardial infarction. Chronic, latent and recurrent infections have been documented, and it is postulated that, like chronic or recurrent C. trachomatis infections, these may produce disease as a consequence of the host's immunological hypersensitivity. Several techniques are available for serological diagnosis: the technique of choice is micro-immunofluorescence, using fixed whole elementary or reticulate bodies as antigen, but antibody responses are highly variable. Traditional alternatives, antigen detection (by direct immunofluorescence or enzyme immunoassay) and cell culture, have major disadvantages. Polymerase chain reactions have not yet been widely applied to the clinical setting. tetracycline antibiotics, erythromycin and quinolones are not very efficacious in the treatment of C. pneumoniae infection. The azalide antibiotic, azithromycin, and the macrolide, clarithromycin, are active in vitro against C. pneumoniae, and may become treatments of choice. The development of anti-chlamydial vaccines remains an important research goal.

Carbenoxolone (duogastrone) and cimetidine in the treatment of duodenal ulcer--a therapeutic trial.

A double-blind, double-dummy trial to compare carbenoxolone (Duogastrone) with cimetidine has been carried out in patients with duodenal ulcer. Sixty patients completed the six week trial period, 31 patients were treated with carbenoxolone and 29 with cimetidine. Both groups were comparable with respect to age, sex, smoking habits and alcohol intake. There were no significant differences between groups during the trial period with respect to symptomatic relief and antacid consumption. Endoscopy after six weeks of therapy showed healing in 61% of patients receiving carbenoxolone and 72% in those receiving cimetidine, a difference which is not significant. No serious side-effects occurred with either drug.