NMR imaging of the diffusion of water at 310 K into semi-IPNs of PEM and Poly(HEMA-co-THFMA)

Magnetic resonance imaging has been used to monitor the diffusion of water at 310 K into a series of semi-IPNs of poly(ethyl methacrylate), PEM, and copolymers of 2-hydroxyethyl methacrylate, HEMA, and tetrahydrofurfuryl methacrylate, THFMA. The diffusion was found to be well described by a Fickian kinetic model in the early stages of the water sorption process, and the diffusion coefficients were found to be slightly smaller than those for the copolymers of HEMA and THFMA, P(HEMA-co-THFMA), containing the same mole fraction of HEMA in the matrix. A second stage sorption process was identified in the later stage of water sorption by the PEM/PTHFMA semi-IPN and for the systems containing a P(HEMA-co-THFMA) component with a mole fraction HEMA of 0.6 or less. This was characterized by the presence of Water near the surface of the cylinders with a longer NMR T-2 relaxation time, which would be characteristic of mobile water, such as water present in large pores or surface fissures. The presence of the drug chlorhexidine in the polymer matrixes at a concentration of 5.625 wt % was found not to modify the properties significantly, but the diffusion coefficients for the water sorption were systematically smaller when the drug was present.

Size distribution curves of senile plaques in patients with Alzheimer’s disease: do plaques grow according to the log-normal model?

The size frequency distributions of diffuse, primitive and cored senile plaques (SP) were studied in single sections of the temporal lobe from 10 patients with Alzheimer’s disease (AD). The size distribution curves were unimodal and positively skewed. The size distribution curve of the diffuse plaques was shifted towards larger plaques while those of the neuritic and cored plaques were shifted towards smaller plaques. The neuritic/diffuse plaque ratio was maximal in the 11 – 30 micron size class and the cored/ diffuse plaque ratio in the 21 – 30 micron size class. The size distribution curves of the three types of plaque deviated significantly from a log-normal distribution. Distributions expressed on a logarithmic scale were ‘leptokurtic’, i.e. with excess of observations near the mean. These results suggest that SP in AD grow to within a more restricted size range than predicted from a log-normal model. In addition, there appear to be differences in the patterns of growth of diffuse, primitive and cored plaques. If neuritic and cored plaques develop from earlier diffuse plaques, then smaller diffuse plaques are more likely to be converted to mature plaques.

Resonance studies of artificial earth satellites

Orbit determination from artificial satellite observations is a key process in obtaining information about the Earth and its environment. A study of the perturbations experienced by these satellites enables knowledge to be gained of the upper atmosphere, the gravity field, ocean tides, solid-Earth tides and solar radiation. The gravity field is expressed as a double infinite series of associated Legendre functions (tesseral harmonics). In contemporary global gravity field models the overall geoid is well determined. An independent check on these gravity field harmonics of a particular order may be made by analysis of satellites that pass through resonance of that order. For such satellites the perturbations of the orbital elements close to resonance are analysed to derive lumped harmonic coefficients. The orbital parameters of 1984-106A have been determined at 43 epochs, during which time the satellite was close to 14th order resonance. Analysis of the inclination and eccentricity yielded 6 lumped harmonic coefficients of order 14 whilst analysis of the mean motion yielded additional pairs of lumped harmonics of orders 14, 28 and 42, with the 14th order harmonics superseding those obtained from analysis of the inclination. This thesis concentrates in detail on the theoretical changes of a near-circular satellite orbit perturbed by the Earth's gravity field under the influence of minimal air-drag whilst in resonance with the Earth. The satellite 1984-106A experienced the interesting property of being temporarily trapped with respect to a secondary resonance parameter due to the low air-drag in 1987. This prompted the theoretical investigation of such a phenomenon. Expressions obtained for the resonance parameter led to the determination of 8 lumped harmonic coefficients, coincidental to those already obtained. All the derived lumped harmonic values arc used to test the accuracy of contemporary gravity field models and the underlying theory in this thesis.

An optical study of human ocular dimensions

Many workers have studied the ocular components which occur in eyes exhibiting differing amounts of central refractive error but few have ever considered the additional information that could be derived from a study of peripheral refraction. Before now, peripheral refraction has either been measured in real eyes or has otherwise been modelled in schematic eyes of varying levels of sophistication. Several differences occur between measured and modelled results which, if accounted for, could give rise to more information regarding the nature of the optical and retinal surfaces and their asymmetries. Measurements of ocular components and peripheral refraction, however, have never been made in the same sample of eyes. In this study, ocular component and peripheral refractive measurements were made in a sample of young near-emmetropic, myopic and hyperopic eyes. The data for each refractive group was averaged. A computer program was written to construct spherical surfaced schematic eyes from this data. More sophisticated eye models were developed making use of linear algebraic ray tracing program. This method allowed rays to be traced through toroidal aspheric surfaces which were translated or rotated with respect to each other. For simplicity, the gradient index optical nature of the crystalline lens was neglected. Various alterations were made in these eye models to reproduce the measured peripheral refractive patterns. Excellent agreement was found between the modelled and measured peripheral refractive values over the central 70o of the visual field. This implied that the additional biometric features incorporated in each eye model were representative of those which were present in the measured eyes. As some of these features are not otherwise obtainable using in vivo techniques, it is proposed that the variation of refraction in the periphery offers a very useful optical method for studying human ocular component dimensions.

Synkinesis of accommodation and vergence during sustained rear vision

It is well established that a synkinetic relationship exists between the accommodation and vergence components of the oculomotor near response such that increased accommodation will initiate a vergence response (i.e. accommodative convergence) and conversely increased vergence will drive accommodation (i.e. convergent accommodation) . The synkinesis associated with sustained near-vision was examined in a student population consisting of emmetropes, late-onset myopes (LOMs) i.e. myopia onset at 15 years of age or later and early-onset myopes (EOMs) i.e. myopia onset prior to 15 years of age. Oculomotor synkinesis was investigated both under closed-loop conditions and with either accommodation or vergence open-loop. Objective measures of the accommodative response were made using an infra-red optometer. Differences in near-response characteristics were observed between LOMs and EOMs under both open- and closed-loop conditions. LOMs exhibit significantly higher levels of disparity-induced accommodation (accommodation driven by vergence under closed-loop conditions) and lower response accommodative convergence/accommodation (AC/A) ratios when compared with EOMs. However no difference in convergent accommodation/convergence (CA/C) ratios were found between the three refractive groups. Accommodative adaptation was examined by comparing the pre- to post-task shift in dark focus (DF) following near-vision tasks. Accommodative adaptation was observed following tasks as brief as 15s. Following a 45s near-vision task, subjects having pre-task DF greater than +0.750 exhibited a marked negative shift in post-task DF which was shown to be induced by beta-adrenergic innervation to the ciliary muscle. However no evidence was found to support the proposal of reduced adrenergic innervation to the ciliary muscle in LOMs. Disparity-vergence produced a reduction in accommodative adaptation suggesting that oculomotor adaptation was not driven by the output of the near-response crosslinks. In order to verify this proposition, the effect of vergence adaptation on CA/C was investigated and it was observed that prism adaptation produced no significant change in the CA/C ratio. This would indicate that in a model of accommodation-vergence interaction, the near response cross-links occur after the input to the adaptive components of the oculomotor response rather than before the adaptive elements as reported in previous literature. The findings of this thesis indicate differences in the relative composition of the aggregate accommodation and vergence responses in the three refractive groups examined. They may also have implications with regard to the aetiology of late-onset myopia.

An investigation into the relationship between pupil and accommodation responses during near vision

A Hamamatsu Video Area Analyser has been coupled with a modified Canon IR automatic optometer. This has allowed simultaneous recording of pupil diameter and accommodation response to be made both statically and continuously, a feature not common in previous studies. Experimental work concerned pupil and accommodation responses during near vision tasks under a variety of conditions. The effects of sustained near vision tasks on accommodation have usually been demonstrated by taking post-task measures under darkroom conditions. The possibility of similar effects on pupil diameter was assessed using static and continuous recordings following a near vision task. Results showed that is luminance levels remained unchanged by using a pre-and post-task bright-empty field then, although accommodation regressed to pre-task levels,pupil diameter remained for several minutes at the contstricted level induced by the task. An investigation into the effect of a sinusoidally-modulated blur-only accommodative stimulus on pupil response demonstrated that response may be reduced or absent despite robust accommodation responses. This suggests that blur-driven acommodation alone may not be sufficient to produce a pupil near response and that the presence of other cues may be necessary. Pupil response was investigated using a looming stimulus which produced an inferred-proximity cue. It was found that a pupil response could be induced which was in synchrony with the stimulus while closed-loop accommodation response was kept constant by the constraints of optical blur. The pupil diameter of young and elderly subjects undertaking a 5 minute reading task was measured to assess the contribution of pupil constriction to near vision function in terms of depth-of-focus. Results showed that in the young subjects pupil diameter was too large to have a significant effect on depth-of-focus although it may be increased in the elderly subjects. Pupil and accommodation reponses to a temporally-modulated stimulus containing all cues present in a normal visual environment was assessed and results showed that as stimulus temporal frequency increased, pupil response showed increasing phase lag relative to closed-loop accommodation. The results of this study suggest that it may be necessary to change the accepted view of the function of pupil response as part of the near vision triad and that further study would be of benefit in particular to designers of vision aids such as, for example, bifocal contact lenses.

The effect of relative distance enlargement on visual acuity in the visually impaired

Background: Prescribing magnification is typically based on distance or near visual acuity. this presumes a constant minimum angle of visual resolution with working distance and therefore enlargement of an object moved to a shorter working distance (relative distance enlargement). this study examines this premise in a visually impaired population. methods: distance letter visual acuity was measured prospectively for 380 low vision patients (distance visual acuity between 0.3 and 2.1 logmar) over the age of 57 years, along with near word visual acuity at an appropriate distance for near lens additions from +4 d to +20 D. demographic information, the disease causing low vision, contrast sensitivity, visual field and psychological status were also recorded. results: distance letter acuity was significantly related to (r = 0.84) but on average 0.1 ± 0.2 logmar better (1 ± 2 lines on a logmar chart) than near word acuity at 25 cm with a +4 d lens addition. in 39. 8 per cent of patients, near word acuity was more than 0.1 logmar worse than distance letter acuity. in 11.0 per cent of subjects, near visual acuity was more than 0.1 logmar better than distance letter acuity. the group with near word acuity worse than distance letter acuity also had lower contrast sensitivity. the group with near word acuity better than distance letter acuity was less likely to have age-Related macular degeneration. smaller print size could be read by reducing working distance (achieved by using higher near lens additions) in 86. 1 per cent, although not by as much as predicted by geometric progression in 14. 5 per cent. discussion: although distance letter and near word acuity are highly related, they are on average 1 logmar line different and this varies significantly between individuals. near word acuity did not increase linearly with relative distance enlargement in approximately one in seven visually impaired, suggesting that the measurement of visual resolution over a range of working distances will assist appropriate prescribing of magnification aids.

A model of the hydrothermal system at Casa Diablo in Long Valley, California, based on resistivity profiles and soil mercury analyses

A description and model of the near-surface hydrothermal system at Casa Diablo, with its implications for the larger-scale hydrothermal system of Long Valley, California, is presented. The data include resistivity profiles with penetrations to three different depth ranges, and analyses of inorganic mercury concentrations in 144 soil samples taken over a 1.3 by 1.7 km area. Analyses of the data together with the mapping of active surface hydrothermal features (fumaroles, mudpots, etc.), has revealed that the relationship between the hydrothermal system, surface hydrothermal activity, and mercury anomalies is strongly controlled by faults and topography. There are, however, more subtle factors responsible for the location of many active and anomalous zones such as fractures, zones of high permeability, and interactions between hydrothermal and cooler groundwater. In addition, the near-surface location of the upwelling from the deep hydrothermal reservoir, which supplies the geothermal power plants at Casa Diablo and the numerous hot pools in the caldera with hydrothermal water, has been detected. The data indicate that after upwelling the hydrothermal water flows eastward at shallow depth for at least 2 km and probably continues another 10 km to the east, all the way to Lake Crowley.

The effect of sexist attitudes on the perception of visual artists by community college and university students

This study compared the effects of sexist labeling on the perceptions of visual artists by the community college and university students and determined their sex role orientation. The 370 students were shown five slides of an artist's works and were given six versions of an artist's biography. It contained embedded sexual labeling (woman, girl, person/ she, man, guy, person/he). The Artist Evaluation Questionnaire was administered to the female and male community college and university students that required the students to evaluate the female and male artists on several aspects of affective and cognitive measures. The questionnaire consisted of 9 items that had to be rated by the participants. In addition, the students filled out the Demographic Questionnaire and the BEM Sex Role Inventory, titled the Attitude Questionnaire. The Analysis of Variance testing procedures were administered to analyze the responses. The results disclosed gender differences in students' ratings. The female artist's work, when the artist was referred to by the neutral sexual label, "person", received significantly higher ratings from the female students. The male students gave the female artist her highest ratings when she was referred to by the low status sexual label, "girl". Both sexes did not express statistically significant preferences for any of the male sexual labels. Gender difference became apparent when it was found that female students rated both sexes equally, and their ratings were lower than those of the male students. The male students rated the female artist's work higher than the work of the male artist. The analysis of the sex role inventory questionnaire revealed the absence of the feminine (expressive) and masculine (instrumental) personalities among the students. The personalities of almost all the students were androgynous, with a few within the range of the near feminine, and a few within the range of the near masculine. The study reveals that there are differences in perception of sexual labels among the community college and university students.

Near miss materno e iniquidades em saúde: análise de determinantes contextuais no Rio Grande do Norte, Brasil

The scope of this study was to identify socioeconomic contextual and health care factors in primary care associated with maternal near misses and their marker conditions. This is an ecological study that used aggregated data of 63 clusters formed by the municipalities of State of Rio Grande do Norte, Brazil, using the Skater method of area regionalization, as the unit of analysis. The ratio of maternal near misses and their marker conditions were obtained from the Hospital Information System of the Brazilian Unified Health System. In multiple linear regression analysis, there was a significant association between maternal near misses and variables of poverty and poor primary health care. Hypertensive disorders were also associated with poverty and poor primary care and the occurrence of hemorrhaging was associated with infant mortality. It was observed that the occurrence of maternal near misses is linked to unfavorable socioeconomic conditions and poor quality health care that are a reflection of public policies that accentuate health inequalities.

Near miss materno e iniquidades em saúde: análise de determinantes contextuais no Rio Grande do Norte, Brasil

The scope of this study was to identify socioeconomic contextual and health care factors in primary care associated with maternal near misses and their marker conditions. This is an ecological study that used aggregated data of 63 clusters formed by the municipalities of State of Rio Grande do Norte, Brazil, using the Skater method of area regionalization, as the unit of analysis. The ratio of maternal near misses and their marker conditions were obtained from the Hospital Information System of the Brazilian Unified Health System. In multiple linear regression analysis, there was a significant association between maternal near misses and variables of poverty and poor primary health care. Hypertensive disorders were also associated with poverty and poor primary care and the occurrence of hemorrhaging was associated with infant mortality. It was observed that the occurrence of maternal near misses is linked to unfavorable socioeconomic conditions and poor quality health care that are a reflection of public policies that accentuate health inequalities.

Prevalência e fatores associados ao Near Miss Materno: inquérito populacional em uma capital do Nordeste Brasileiro

The scope of this study was to determine the prevalence of near misses and complications during pregnancy and the puerperal period, identifying the main clinical and intervention markers and socioeconomic and demographic factors associated with near misses. It involved a cross-sectional, population-based and probabilistic study with multi-stage complex sampling design conducted in Natal, State of Rio Grande do Norte, Brazil. A validated questionnaire was given to 848 women aged 15 to 49 identified in 8,227 households in 60 census sectors. In theanalysis of associations, the Chi-square test applied and calculated the prevalence ratio (PR) with Confidence Interval (CI) of 95% and 5% significance. The prevalence of maternal near misses was 41.1/1000LB, with hospitalization in an Intensive Care Unit (19.1/1000LB) and eclampsia (13.5/1000LB) being the most important markers. The prevalence of complications during pregnancy and the puerperal period was 21.2%. The highest prevalence of near misses was observed in older women, of black/brown race and low socioeconomic status. Conducting population surveys is feasible and may add important information to the study of near misses and the markers highlight the need for enhancing maternal care to reduce health inequality.

Prevalência e fatores associados ao Near Miss Materno: inquérito populacional em uma capital do Nordeste Brasileiro

The scope of this study was to determine the prevalence of near misses and complications during pregnancy and the puerperal period, identifying the main clinical and intervention markers and socioeconomic and demographic factors associated with near misses. It involved a cross-sectional, population-based and probabilistic study with multi-stage complex sampling design conducted in Natal, State of Rio Grande do Norte, Brazil. A validated questionnaire was given to 848 women aged 15 to 49 identified in 8,227 households in 60 census sectors. In theanalysis of associations, the Chi-square test applied and calculated the prevalence ratio (PR) with Confidence Interval (CI) of 95% and 5% significance. The prevalence of maternal near misses was 41.1/1000LB, with hospitalization in an Intensive Care Unit (19.1/1000LB) and eclampsia (13.5/1000LB) being the most important markers. The prevalence of complications during pregnancy and the puerperal period was 21.2%. The highest prevalence of near misses was observed in older women, of black/brown race and low socioeconomic status. Conducting population surveys is feasible and may add important information to the study of near misses and the markers highlight the need for enhancing maternal care to reduce health inequality.

Annotated record of the detailed examination of Mn deposits from ANTIPODE Expedition stations

Deep-sea sediment cores from Scripps Institution of Oceanography's ANTIPODE Expedition were described to identify visually distinct units based on color, texture, or other feature, sedimentary structures, lithology and abundance of component grains, and paleontology. Sixty-eight cores were examined, of which 34 are large diameter piston cores. Photographs and graphic lithology legs are included as PLATES 1-48. ANTIPODE Expedition recovered cores from: the Monterey-Ascension Fan, the Northeast Pacific, the Aleutians, the Northwest Pacific, the Philippine Sea, Indonesia, the Tonga Ridge, the Seychelles, Chagos Archipelago, the Mid-Indian Ridge, the Bay of Bengal, near Sumatra, and near the Cocos Island in the Indian Ocean. The purpose of this report is to present sufficient basic data on ANTIPODE cores for invesiigators to choose samples for their own research.

Multi-proxy record of planktonic and benthic foraminiferal d18O, and Mg/Ca-derived surface and lower thermocline temperatures in sediment core SO18471 (GIK18471), Timor Sea

Paleostudies of the Indonesian Throughflow (ITF) are largely based on temperature and salinity reconstructions of its near surface component, whereas the variability of its lower thermocline flow has rarely been investigated. We present a multi-proxy record of planktonic and benthic foraminiferal d18O, Mg/Ca-derived surface and lower thermocline temperatures, X-ray fluorescence (XRF)-derived runoff and sediment winnowing for the past 130 ka in marine sediment core SO18471. Core SO18471, retrieved from a water depth of 485 m at the southern edge of the Timor Strait close to the Sahul Shelf, sits in a strategic position to reconstruct variations in both the ITF surface and lower thermocline flow as well as to investigate hydrological changes related to monsoon variability and shelf dynamics over time. Sediment winnowing demonstrates that the ITF thermocline flow intensified during MIS 5d-a and MIS 1. In contrast during MIS 5e, winnowing was reduced and terrigenous input increased suggesting intensification of the local wet monsoon and a weaker ITF. Lower thermocline warming during globally cold periods (MIS 4 - MIS 2) appears to be related to a weaker and contracted thermocline ITF and advection of warm and salty Indian Ocean waters.