Showing papers by "University of Manitoba published in 1986"

Enhancement of Mammographic Features by Optimal Adaptive Neighborhood Image Processing

Abstract: X-ray mammography is the only breast cancer detection technique presently available with proven efficacy. Mammographic detection of early breast cancer requires optimal radiological or image processing techniques. We present an image processing approach based on adaptive neighborhood processing with a new set of contrast enhancement functions to enhance mammographic features. This procedure brings out the features in the image with little or no enhancement of the noise. We also find that adaptive neighborhoods with surrounds whose width is a constant difference from the center yield improved enhancement over adaptive neighborhoods with a constant ratio of surround to center neighborhood widths.

A survey of 112,000 anaesthetics at one teaching hospital (1975-83).

Abstract: This paper describes the outcome of a nine-year post-anaesthetic followup program in a large teaching hospital (N = 112,721 anaesthetics). Between time periods 1975-78 and 1979-83, more seriously ill patients (higher ASA physical status) were being treated. Anaesthetic practice also changed, with an increased use of balanced (multiple drug) anaesthetic procedures, a decrease in the use of halothane and an increase in the use of monitoring. Nonfatal anaesthetic complications--intraoperative, recovery room and postoperative--were rare but there was an increase in the reported complication rate over time. From 1975-78, 7.6 per cent of all cases had at least one intraoperative complication and from 1979-83, this rose to 10.6 per cent of all cases. For recovery room complications, there was an increase to 5.9 per cent in 1979-83 from 3.1 per cent in 1975-78. In time period 2 there was a 9.4 per cent chance of having a postoperative anaesthetic-related complication, and a 0.45 per cent chance of a significant morbidity as a result. This represents an increase over time period 1 (8.9 and 0.40 per cent respectively). It is concluded that the anaesthetic experience, while associated with low mortality rates in recent years, is still associated with significant morbidity. It is conjectural at present whether this is reflective of preoperative patient status, anaesthetic practice, or other undefined variables associated with an operative experience.

Expression of the c-myc protooncogene in human prostatic carcinoma and benign prostatic hyperplasia

Abstract: We have examined the level of c-myc transcripts in prostate tissue obtained from patients with both benign prostatic hyperplasia and adenocarcinoma of the prostate. A significantly higher level of c-myc transcripts is observed in patients with adenocarcinoma (P less than 0.05). In addition, a subset of patients with adenocarcinoma had levels of c-myc transcripts 2-fold higher than the mean level for this group. These preliminary results indicate that the investigation of c-myc levels as a prognostic indicator in prostatic carcinoma is warranted.

Intracultural Variation in Folk Medical Knowledge: A Comparison Between Curers and Noncurers

Abstract: This paper investigates variation in folk medical beliefs in a Tarascan community in west-central Mexico. The data are from a structured interview completed with ten traditional curers and a like-sized comparison group of noncurers. Three possible patterns of interinformant agreement are described and tested using the quadratic assignment program. The results suggest that although curers and noncurers do differ, the differences are not so great that they represent two variant systems of medical beliefs. Rather, there is a single system of beliefs common to both groups, but with curers showing higher agreement among themselves in expressing this system than noncurers. This finding, and a related one showing higher agreement among older informants, are explained in terms of culture learning. Curers and older people share more knowledge about illness because of their greater experience in both dealing with and communicating about illness. A model of folk medical knowledge is then presented and systematic variation from this model examined.

Perfectionism, stress, and vulnerability to depression

Abstract: The relation between stressful life events, perfectionism, and relative depression in a university sample was studied. Results indicated that the relationship between stressful events and depression was significant only for participants who scored above the median on a scale of perfectionistic attitudes. Additional regression analyses indicated that later depression was significantly predicted by prior depression and current perfectionistic attitudes. On the other hand, stressful life events and prior perfectionistic attitudes did not significantly predict later depression. Taken together these findings suggest that perfectionistic attitudes are a concomitant of depression and that they may mediate the relationship between stress and depression. Although strong evidence of cognitive vulnerability was not obtained, the need for controlled experimentation with clinical samples was discussed.

Quantitative Approaches to Reliability Assessment in Pipe Networks

Abstract: Two quantitative approaches to the incorporation of reliability measures in the least‐cost design of looped water distribution networks are developed and assessed. Both approaches begin by obtaining an “optimal” layout design through linear programming. The first approach, addresses the probability of isolating a node through simultaneous failure of all links connected directly to that node. The second approach attempts to recognize redundancy by minimizing the deviations in the reliabilities of all pipes connected to each node within the network. In both cases, the probability of failure of individual links is modeled using the Poisson probability distribution. Comparison of the techniques suggests that minimizing the differences in the reliabilities of pipes connected to each node seems the most promising.

Different formulations for numerical solution of single or multibodies of revolution with mixed boundary conditions

Abstract: A numerical method for determining the electromagnetic field in the presence of one or several bodies of revolution is presented. The objects can be made of conductors, dielectrics or their combinations. The excitation is assumed to be due to a plane wave or infinitesimal electric dipoles located within or outside the dielectric. Several formulation types are considered and used to investigate the scattering by different objects. It is found that for moderate values of the dielectric constant, all formulation types give satisfactory results. However, for small or large relative permittivities the solution accuracies depend on the formulation type. As an application of the method to practical problems, two special cases of dielectric rod and microstrip antennas are considered. These antennas have widespread applications and the proposed method can be used to investigate their performance accurately.

The role of sulfate reduction in long term accumulation of organic and inorganic sulfur in lake sediments1

Abstract: .Sulfate reduction and the accumulation of reduced sulfur in epilimnetic sediments were studied in lakes in southern Norway, the Adirondack Mountains, and at the Experimental Lakes Area (ELA) of northwestern Ontario. In all of the lakes, in addition to the previously known formation of acid volatile sulfur, sulfate reduction also produced substantial quantities of pyrite and organic sulfur compounds. In g-month in situ experiments at ELA using 35S, there was a large loss (55%) with time of the S initially reduced and deposited in the sediments and a preferential loss of inorganic S compounds which led to a predominance of organic 35S accumulation in the sediments. An intensive study of long term accumulation of sulfur in the epilimnetic sediments of four Adirondack lakes also showed that the most important long term end product of sulfate reduction was organic S and that sulfate reduction was the major source of S to the sediments. Because of the high concentrations of iron in all of the sediments we sampled and because of the long term storage of sulfur in sediments, mostly as organic S, iron did not limit iron sulfide accumulation in these sediments. Iron limitation is unlikely to occur except in unusual circumstances. This study indicates that formation of organic S in epilimnetic sediments is primarily responsible for H+ consumption via sulfate reduction in acidified lakes.

Group Properties of Cellular Automata and VLSI Applications

Abstract: The study of one-dimensional cellular automata exhibiting group properties is presented The results show that only a certain class of cellular automata rules exhibit group characteristics based on rule multiplication However, many other of these automata reveal groups based on permutations of their global states It is further shown how these groups may be utilized in the design of modulo arithmetic units The communication properties of cellular automata are observed to map favorably to optimal communication graphs for VLSI layouts They exploit the implementation medium and properly address the physical limits on computational structures Comparisons of cellular automata-based modulo arithmetic units with other VLSI algorithms are presented using area-time complexity measures

Microbial consumption of nitric and sulfuric acids in acidified north temperate lakes1

Abstract: Rates of sulfate reduction and denitrification were measured in the sediments of unacidified, experimentally acidified, and atmospherically acidified lakes in North America and Norway. These data, plus profiles of porewater and sediment chemistry, demonstrated that in all of the lakes Hb was being actively consumed by both sulfate reducers and denitrifiers. Both of these microbial activities were assayed in sediments overlaid by oxygenated water, demonstrating that anoxic hypolimnia are not required for in situ alkalinity production. Neither short term experimental acidification nor long term atmospheric acidification had detectably inhibited the activity of these two types of bacteria. Both processes were active at pH 4.5. In lakes that were receiving significant quantities of both nitric and sulfuric acids, short term H b consumption from denitrification was 1.5-2 times faster than H-’ consumption by sulfate reduction. However on an annual basis, because of loss of reduced sulfur during fall and winter, long term H+ consumption by denitrification was estimated to be 4-5 times as large as H+ consumption by sulfate reduction.

Retention and release of S from A freshwater wetland

Abstract: A freshwater wetland at the Experimental Lakes Area in northwestern Ontario stored most of the SO42− received annually from precipitation, runoff and experimental additions The S budget was determined for a small fen spray irrigated with H2SO4 and HNO3 Annual S retention was greatest during the first year of experimental addition of H2SO4 (73% of input in 1983) Retention was lowest (22%) in 1984, a year of lower than average precipitation with a long hot summer During years with hot, dry summers, SO42− was produced from the reoxidation of reduced S compounds in the peat and released to surface waters The autumn SO42− pulse was accompanied by the release of Ca and Mg but was not accompanied by a H+ release as has been detected in eastern Ontario and southern Norway, areas which receive more acidic precipitation

Reliability of Consecutive-k-out-of-n:F Systems with (k-1)-step Markov Dependence

Abstract: Reliabilities are studied for consecutive-k-out-of-n:F systems with component failures having (k-1)-step Markov dependence.

Distribution of adenosine deaminase activity in rat brain and spinal cord

Abstract: The activity of adenosine deaminase (ADA) was measured in 62 discrete regions of the CNS, and in some autonomic and sensory ganglia, peripheral nerves, and peripheral tissues of the rat using an automated high-pressure liquid chromatography (HPLC) method. The formation of inosine and hypoxanthine as a measure of ADA activity in homogenates of brain was optimal at pH 7.0, linear for up to 60 min at 37 degrees C using 500 microM adenosine as substrate, and linear with protein concentrations ranging from 0.05 to 0.8 mg. The Km and Vmax values for ADA activity in homogenates of whole brain were 47 microM and 107 nmol/mg protein/30 min, respectively. Among the CNS regions examined, the highest activity was found in posterior hypothalamic magnocellular nuclei and the lowest in hippocampus. In general, spinal cord contained relatively low levels of ADA activity, with that in dorsal cord approximately 40% higher than ventral cord. In the periphery, parasympathetic ganglia contained higher levels of ADA than sensory ganglia and brain. Most peripheral tissues--including adrenal gland, lung, liver, and anterior and posterior pituitary--exhibited activity comparable to levels in the posterior hypothalamus. ADA activity in thymus was about 10 times higher than any other tissue examined. The uneven distribution of ADA activity in the rat CNS corresponds well with the immunohistochemical localization of this enzyme in discrete neural systems of this species. Structures that contain high ADA activity exhibit intense ADA immunostaining of neuronal perikarya and/or fibers.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of various parameters of circular microstrip antennas on their radiation efficiency and the mode excitation

Abstract: The numerical solution of circular microstrip antenna is carried out using the method of moment. The effect of the probe position, The dielectric permittivity of the substrate, and the substrate thickness on the radiation pattern and the mode excitation efficiency are studied. It is found that the probe position and the patch size can be used to control the mode excitation efficiency, and heigher order modes can be generated using only one feed location. Also, the finite ground plane can be used to improve the symmetry of the radiation patterns. The technique is general and can be used to investigate other scattering and antenna problems involving axisymmetric geometries.

Fetomaternal transplacental hemorrhage during pregnancy and after delivery.

Abstract: One third of very weakly Rh-immunized women show no increase in their level of Rh immunization during pregnancy and after delivery. Administration of 300 micrograms of Rh immune globulin at 6-week intervals does not alter the incidence of lack of progression of Rh immunization in such women. Thirty-three Rh-positive women who ultimately delivered ABO-compatible babies, had Kleihauer fetal transplacental hemorrhage (TPH) screening tests carried out at 2-week intervals during pregnancy and shortly after delivery. One third of the 33 women had no detectable TPH or a TPH of 0.01 ml of fetal red cells. We conclude that one third of weakly Rh-immunized women failed to show any progression of their Rh immune response during pregnancy or after delivery because they were exposed to too few fetal red cells (0.01 ml or less) to produce such a response.

Repeated exposure to violent and nonviolent pornography: Likelihood of raping ratings and laboratory aggression against women

Abstract: This study examined the relatively long-term effects of repeated exposure to violent and nonviolent pornography on male' laboratory aggression against women. Self-reported likelihood of raping was also assessed as an individual differences variable that might mediate susceptibility to the effects of pornography and to ascertain whether it predicted actual aggressive behavior. Subjects were randomly assigned to the sexually violent, sexually nonviolent, or control exposure conditions. Those assigned to the sexually violent or sexually nonviolent conditions were exposed over a four-week period to ten stimuli including feature-length films and written and pictorial depictions, whereas control subjects were not exposed to any stimuli. About a week following the end of the exposure phase, subjects participated in what they believed to be a totally unrelated experiment in which aggression was assessed within a Buss paradigm. Exposure to the violent or nonviolent pornographic stimuli was not found to affect laboratory aggression. These data are discussed in terms of a recent analysis of media effects emphasizing the temporary activation of ideas in audience' minds. Likelihood of raping ratings was found to predict laboratory aggression.

A Numerical Model of Temporomandibular Joint Loading

Abstract: A numerical model of the mandible, its articulating surfaces, and the forces exerted by the primary masticatory muscles has been developed for the purpose of investigating loading of the temporomandibular joint. Evidence is presented which shows that the temporomandibular joint. Evidence is presented which shows that the temporomandibular joint is a load-bearing joint over the normal functional range of bite-force positions and angles. In this investigation, temporomandibular joint loads were found to vary from a maximum appositional force of 60% of the bite force (when bite forces were applied to the incisors) to a distracting force of about 5% of the bite force (when applied to the distal surfaces of the third molars). TMJ loads tended to reach a minimum as a result of vertically directed bite forces positioned at the second molars. A range of conditions in which bite forces were directed parallel to or within approximately 20 degrees of the mid-sagittal plane was found to be conducive to stability of the temporomandibular joint. This stability included symmetry in the direction and in the magnitude of condylar loads as well as the presence of small forces tending to oppose the condyle and articular eminence. TMJ loads tended to reach a maximum in response to mediolaterally directed bite forces. This result is consistent with the fact that no muscle of mastication exhibits a spatial orientation in which the muscle fibers are predominantly mediolateral in direction.

Impairment of cerebral blood flow autoregulation in the newborn lamb by hypoxia.

Abstract: Autoregulation of cerebral blood flow has been demonstrated in both fetal and newborn animal models under normoxic conditions. In the present experiments we have attempted to define the minimal hypoxic insult which impairs autoregulation in the newborn lamb and to assess the time to recovery. We measured cerebral blood flow by the intracarotid 133Xe method in fifteen 4- to 9-day-old lambs and tested autoregulation of cerebral blood flow by increasing blood pressure 20-30% with phenylephrine. Autoregulation was tested in the control state and at successive time intervals after an hypoxic stress (PaO2 of 30 mm Hg) of 10 or 20 min. We found that cerebral autoregulation was abolished after 20 min of hypoxia and recovered within 7 h. Since this model identifies the minimal hypoxic insult to abolish autoregulation it might be used to study means to protect autoregulation or to hasten its recovery after hypoxia.

Brood reduction in the American white pelican (Pelecanus erythrohynchos)

Abstract: American white pelicans (Pelecanus erythrorhynchos) breeding in colonies at East Shoal Lake, Manitoba, Canada exhibited a mean hatching asynchrony of 2.5 days in 2-egg clutches. This resulted in a size difference between chicks which facilitated sibling dominance, harassment and lack of food for the subordinate chick. Only one young survived per nest. In marked broods, the secondhatched chick survived in 20% of successful nests. Manipulated clutch sizes (1, 2 and 3 eggs or chicks per nest) revealed that the presence of a second chick contributes significantly to the reproductive success of the parents. Results support the hypothesis that the second egg functions as a form of “insurance” against early loss of the first egg or chick. The parents, by establishing hatching asynchrony, by nonintervention in sibling aggression, and by selectively feeding the dominant chick, maximize their chance of rearing the most viable young.

Quaternary evaporites and hydrological changes, Lake Tyrrell, North‐West Victoria

Abstract: Lake Tyrrell, a saline playa in semi‐arid north‐western Victoria, records a long history in which a succession of lacustrine and aeolian environments can be related to past hydrologic variations. Cores through the saline evaporitic facies reveal a vertical pattern reflecting cyclic changes through time. Detrital clastics predominated during deep‐water lacustral phases; evaporites were deposited during drying phases. A model, depicting surface‐groundwater interaction during discrete stages of a typical cycle, relates changes in water depth, salinity and typical depositional facies. On the drying trend, the sequence evolves through carbonate to sulphate deposition. Progressive reduction in water level results in partial drying and production of the groundwater outcrop playa stage. Salt efflorescence and production of detrital pelletal clays provide parent materials for aeolian transport and dune building. Any additional fall in watertable permits downward leaching of salts, plant colonization of th...