http://hdl.handle.net/2440/14760 Search the Channel search http://digital.library.adelaide.edu.au/dspace/simple-search http://hdl.handle.net/2440/53359 Title: Corrected head position. <br/> <br/>Author: Barbera, Andrew Lawrence. <br/> <br/>Abstract: Background: Historically, many reference lines and planes of the human skull have been used in an attempt to depict the head in a natural head position (NHP) which is a relaxed/balanced position when looking ahead at their eye level. Head position correction has been attempted in fields such as anatomy, art, anthropology, orthodontics, oral and maxillofacial surgery, plastic surgery, and forensics. In orthodontics, oral and maxillofacial surgery, and plastic surgery, corrected head position (CHP) is particularly important for diagnosis of the normality/protrusion/retrusion of the patient’s facial skeleton. Usually a single plane, such as Frankfurt horizontal, is used to correct head position, but its angulation is variable between individuals, because each individual’s anatomy is unique. It has been found previously that the Neutral Horizontal Axis (NHA), Frankfurt horizontal (FH), Krogman-Walker plane (KW plane), and Palatal plane (P plane) demonstrated near parallelism, and these planes averaged -1 to -2 degrees from the true horizontal (HOR, which is a horizontal plane determined as being perpendicular to the earth’s gravitational force) with subjects in NHP. Methods: Craniofacial planes were measured in an Aboriginal Australian sample and in two contemporary samples obtained from Australian orthodontic practices, and the findings were compared with previous studies. Each sample consisted of 40 individuals (20 males and 20 females) with subjects in NHP. The Aboriginal Australian sample was longitudinal (T1, mean age 10 years; T2, mean age 14 years, and T3, mean age 18 years) enabling NHP to be assessed over approximately 8 years. A soft tissue Ear - nose plane (EN plane) was also investigated. Results: NHP reproducibility over 8 years demonstrated a mean of absolute difference of 2.9 degrees, with a range of differences from -7.9 to 8.2 degrees and a standard deviation of differences equal to 3.6 degrees. The Neutral Horizontal Axis (NHA), Frankfurt horizontal (FH), Krogman-Walker plane (KW plane), and Palatal plane (P plane) demonstrated near parallelism with each other, and averaged between 0 and -3 degrees from HOR. On average, EN plane was horizontal but was variable. Conclusions: NHP is not consistently reproducible at the individual level. For hard tissue images, the combined use of NHA, FH, KW plane, and P plane enables prediction of CHP. Additionally, the rectangular shape of the lower orbit - nasal airway region appears to be useful for correcting head position. In facial soft tissue images, EN plane in combination with other visual factors helps to correct head position. Simple geometry enables this head position correction to be performed from any view of the head where relevant landmarks are seen. Mon, 29 Oct 2007 22:58:59 GMT http://hdl.handle.net/2440/53358 Title: A life course approach to measuring socioeconomic position in population surveillance and its role in determining health status. <br/> <br/>Author: Chittleborough, Catherine R. <br/> <br/>Abstract: Measuring socioeconomic position (SEP) in population chronic disease and risk factor surveillance systems is essential for monitoring changes in socioeconomic inequities in health over time. A life course approach in epidemiology considers the long-term effects of physical and social exposures during gestation, childhood, adolescence, and later adult life on health. Previous studies provide evidence that socioeconomic factors at different stages of the life course influence current health status. Measures of SEP during early life to supplement existing indicators of current SEP are required to more adequately explain the contribution of socioeconomic factors to health status and monitor health inequities. The aim of this thesis was to examine how a life course perspective could enhance the monitoring of SEP in chronic disease and risk factor surveillance systems. The thesis reviewed indicators of early life SEP used in previous research, determined indicators of early life SEP that may be useful in South Australian surveillance systems, and examined the association of SEP over the life course and self-rated health in adulthood across different population groups to demonstrate that inclusion of indicators of early life SEP in surveillance systems could allow health inequities to be monitored among socially mobile and stable groups. A variety of indicators, such as parents’ education level and occupation, and financial circumstances and living conditions during childhood, have been used in different study designs in many countries. Indicators of early life SEP used to monitor trends in the health and SEP of populations over time, and to analyse long-term effects of policies on the changing health of populations, need to be feasible to measure retrospectively, and relevant to the historical, geographical and sociocultural context in which the surveillance system is operating. Retrospective recall of various indicators of early life SEP was examined in a telephone survey of a representative South Australian sample of adults. The highest proportions of missing data were observed for maternal grandfather’s occupation, and mother’s and father’s highest education level. Family structure, housing tenure, and family financial situation when the respondent was aged ten, and mother and father’s main occupation had lower item non-response. Respondents with missing data on early life SEP indicators were disadvantaged in terms of current SEP compared to those who provided this information. The differential response to early life SEP questions according to current circumstances has implications for chronic disease surveillance examining the life course impact of socioeconomic disadvantage. While face-to-face surveys are considered the gold standard of interviewing techniques, computer-assisted telephone interviewing is often preferred for cost and convenience. Recall of father’s and mother’s highest education level in the telephone survey was compared to that obtained in a face-to-face interview survey. The proportion of respondents who provided information about their father’s and mother’s highest education level was significantly higher in the face-to-face interview than in the telephone interview. Survey mode, however, did not influence the finding that respondents with missing data for parents’ education were more likely to be socioeconomically disadvantaged. Alternative indicators of early life SEP, such as material and financial circumstances, are likely to be more appropriate than parents’ education for life course analyses of health inequities using surveillance data. Questions about family financial situation and housing tenure during childhood and adulthood asked in the cross-sectional telephone survey were used to examine the association of SEP over the life course with self-rated health in adulthood. Disadvantaged SEP during both childhood and adulthood and upward social mobility in financial situation were associated with a reduced prevalence of excellent or very good health, although this relationship varied across gender, rurality, and country of birth groups. Trend data from a chronic disease and risk factor surveillance system indicated that socioeconomic disadvantage in adulthood was associated with poorer self-rated health. The surveillance system, however, does not currently contain any measures of early life SEP. Overlaying the social mobility variables on the surveillance data indicated how inequities in health could be differentiated in greater detail if early life SEP was measured in addition to current SEP. Inclusion of life course SEP measures in surveillance will enable monitoring of health inequities trends among socially mobile and stable groups. Life course measures are an innovative way to supplement other SEP indicators in surveillance systems. Considerable information can be gained with the addition of a few questions. This will provide further insight into the determinants of health and illness and enable improved monitoring of the effects of policies and interventions on health inequities and intergenerational disadvantage. Wed, 29 Oct 2008 22:58:59 GMT http://hdl.handle.net/2440/53357 Title: Platelet and endothelial function : Polycystic Ovary Syndrome and the renin-angiotensin system. <br/> <br/>Author: Rajendran, Sharmalar <br/> <br/>Abstract: The phenomenon of platelet hyperaggregability and decreased platelet responsiveness to nitric oxide (also termed as nitric oxide resistance), documented in several cardiovascular disease states, is associated with adverse cardiovascular outcomes. The series of experiments described in this thesis address primarily some aspects of the pathophysiology, epidemiology and therapy of the phenomenon of end-organ resistance to nitric oxide (NO) in two important conditions, that are closely associated with cardiovascular risk factors and disease states:- 􀂄 Polycystic ovary syndrome, which is closely linked with the metabolic syndrome and premature subclinical atherosclerosis. 􀂄 The renin-angiotensin system, which is recognized as a significant mediator in the pathophysiology of a number of cardiovascular disease states. The first study examined the epidemiology/pathophysiology of putative platelet/endothelial dysfunction in young individuals with PCOS. The subsequent studies focused on the potential impact of the renin-angiotensin system on platelet and endothelial function. This mechanistic review is set in the context of a number of recent major clinical studies which have demonstrated surprising efficacy of certain angiotensin-converting enzyme (ACE) inhibitors (ramipril and perindopril) in the prevention of thrombotic processes. Thus we tested the hypothesis whether ACE inhibitor ramipril sensitizes platelets to NO (as a potential mechanism for improved cardiovascular outcomes) in a high risk patient cohort. In addition, particular attention will be given to the emerging role of the heptapeptide Angiotensin- (1-7), a possible physiological antagonist to Angiotensin II in the vasculature and the limitation of the current literature concerning potential effects of the renin-angiotensin system on thrombotic mechanisms. Wed, 29 Oct 2008 22:58:59 GMT http://hdl.handle.net/2440/53356 Title: Identifying nutritive, physical and volatile characteristics of oaten and lucerne hay that affect the short-term feeding preferences of lactating Holstein Friesian cows and Thoroughbred horses. <br/> <br/>Author: Pain, Sarah Jean. <br/> <br/>Abstract: Feeding behaviour is controlled by the integration of both perceived cues from the plant and postingestive signals received by the animal. In general practice, dairy cattle are presented with a variety of feedstuffs throughout each day, in addition to changing feedstuffs over time. In the Australian context, the feeds generally include fodder (usually hay) and pasture whilst grazing, as well as various concentrates. For horses that are stabled for prolonged periods, their diet consists of fodder (again usually hay or chaff) and concentrates, in addition to the pasture consumed whilst allowed access to graze. In such situations, where animals are presented with a range of feedstuffs, some of them novel and for discrete periods of time, it is important that they readily accept the feeds when they are first presented to them. For both lactating dairy cows and performance horses, for example, it is important to avoid periods of low intake, as this can have immediate and sometimes longer-term consequences to animal performance. The daily rate of food intake is the single most important factor affecting animal performance and productivity (Illius et al. 2000) and an animal‟s responses to a feedstuff can be considered the ultimate measure of its quality. The animal‟s first response to the presentation of a new feed, which in this particular study was oaten or lucerne hay, is its level of voluntary intake, which depends in part on palatability. Palatability is an integrative term (Provenza 1995); to provide a quantitative measure of the acceptability of a feedstuff, a „preference value’ can be obtained by describing the preference of one hay relative to an alternate hay also on offer. The Australian fodder industry is increasingly adopting more objective measures of hay quality to improve marketing opportunities, especially in the export industry, and to meet the demands and expectations of local and overseas purchasers of hay. Being able to efficiently and reliably predict the preference value of any particular hay would be beneficial to processors, exporters, users (purchasers) of hay, and possibly plant breeders, to make more informed decisions. This thesis describes a comprehensive analysis of the chemical and physical characteristics of a selected number of oaten and lucerne hays and their relationship to the acceptability or „preference value‟ of the hays for lactating Holstein Friesian cows and Thoroughbred horses. The project aimed to (i) quantify preference values for a large number of oaten hays with dairy cows and horses and a similarly large number of lucerne hays with horses only, and (ii) develop predictive equations for animal preferences based on the chemical and physical properties of the hays and the animal‟s short-term rate of consuming the hays. A total of approximately 8,500 preference tests were conducted with 85 oaten hays offered to lactating Holstein Friesian cows and Thoroughbred horses, and 70 lucerne hays offered to Thoroughbred horses. The hays were selected to cover a range of nutritive values. The intake rate and preferences for all the hays were quantified in a series of tests replicated over time and with different animals. Each „trial‟ hay was offered with four „standard‟ hays (in separate tests). A suite of chemical (nutritive value) traits and physical traits were quantified for the hays. An assessment of the „odour profile‟ was also included in the characterisation of the hays. The nutritive, physical and volatile traits were then related to hay preference values in multiple and simple linear regression models and equations generated to predict hay preference values. A prediction of hay preference made directly from the spectra obtained by near infrared reflectance spectroscopy (NIRS) was also developed. Overall, the average preference value of an oaten hay (i.e., that obtained using the comparisons with all four standard hays) could be predicted from a range of nutritive value traits, typically the contents of acid detergent fibre (ADF), hemicellulose, crude protein (CP) and water soluble carbohydrates (WSC) - with a correlation co-efficient of about 79% with cows and 61% for horses. Acid detergent fibre and CP contents tended to have the biggest influence on preference value for both cows and horses, followed by WSC and hemicellulose content. Examination of lucerne hays offered to horses increased the correlation co-efficient to 74%, with ADF, hemicellulose and CP each having a similar magnitude of effect. This means that these traits, with an appropriate weighting for each, could account for up to about three-quarters of the variation in hay preference values for cows and horses. The in vitro digestibility of dry matter (IVD) of oaten and lucerne hay was nearly as accurate in predicting preference values as using the four nutritive value traits of ADF, hemicellulose, CP and WSC, which was anticipated as digestibility is a function of these chemical traits. Hay physical traits could also be used to predict preference values, although not as accurately as the nutritive value traits or IVD. Of the physical traits, shear energy had the largest effect (co-efficient approximately -1.15 compared to an average of -0.35 for the other traits in the equation). The use of NIRS to directly predict preference values was also encouraging, with the best calibration model yielding a correlation co-efficient of 61 to 81%, depending on the hay (oaten or lucerne) and the animal (cows or horses). Of the total 120 volatile compounds isolated from the oaten hays, six had some relationship with cow preferences and there were also six oaten hay volatiles related to horse preferences. Of the oaten hay volatiles significantly related to preference, four were positively related to cow preference whilst two were negatively related to cow preference. Similarly there were four volatiles positively related to horse preference and two consistently negatively related. Of the six oaten hay volatiles found to influence the preferences of dairy cows and horses, four were common to both species. Of the total of 147 volatile compounds isolated from the lucerne hays, 15 had some relationship with horse preference, with nine positively related to horse preference and six negatively related. The data reported here suggest that a predicted preference value for a hay can be generated using commonly measured quality traits, which would improve a buyer‟s confidence of animals responding favourably when first offered the hay. More specifically, for an average preference value, the most reliable prediction equation was based on nutritive value traits: ADF, hemicellulose, crude protein and water soluble carbohydrates solely. Alternatively a combination of nutritive and physical traits can be used to predict preference: in vitro digestibility, crude protein, water soluble carbohydrates and shear energy. The visible and near infrared spectra obtained by NIRS was also a promising method of prediction, and given the speed and affordability of NIRS, this technology could be further refined and used for routine measurement of predicted hay preference values. The volatile compounds shown to influence preference value of the hay should be identified and further research undertaken to investigate novel approaches to manipulate the preference of hays. Caution should be taken when attempting to use these prediction equations on a single specific hay in a single specific situation. The predictions and relationships investigated in this thesis are based on populations of hays and preferences of a group of animals and therefore some care should be taken when applying them to a particular situation with difference circumstances. Other factors that can influence feed preferences include an animal‟s feeding experiences, basal diet and diet history and various environmental factors unaccounted for here. Mon, 29 Oct 2007 22:58:59 GMT