992 resultados para McEwen, Donald
Resumo:
The natriuretic peptide (NP) family consists of multiple subtypes in teleosts, including atrial, B-type, ventricular, and C-type NPs (ANP, BNP, VNP, CNP-1–4, respectively), but only ANP, BNP, CNP-3, and CNP-4 have been identified in tetrapods. As part of understanding the molecular evolution of NPs in the tetrapod lineage, we identified NP genes in the chicken genome. Previously, only BNP and CNP-3 have been identified in birds, but we characterized two new chicken NP genes by cDNA cloning, synteny and phylogenetic analyses. One gene is an orthologue of CNP-1, which has only ever been reported in teleostei and bichir. The second gene could not be assigned to a particular NP subtype because of high sequence divergence and was named renal NP (RNP) due to its predominant expression in the kidney. CNP-1 mRNA was only detected in brain, while CNP-3 mRNA was expressed in kidney, heart, and brain. In the developing embryo, BNP and RNP transcripts were most abundant 24 h post-fertilization, while CNP mRNA increased in a stage-dependant manner. Synthetic chicken RNP stimulated an increase in cGMP production above basal level in chicken kidney membrane preparations and caused a potent dose-dependant vasodilation of pre-constricted dorsal aortic rings. From conserved chromosomal synteny, we propose that the CNP-4 and ANP genes have been lost in chicken, and that RNP may have evolved from a VNP-like gene. Furthermore, we have demonstrated for the first time that CNP-1 is retained in the tetrapod lineage.
Resumo:
Hyaluronan (HA) is a glycosaminoglycan that is synthesized by a family of enzymes called hyaluronan synthases (HASs), of which there are three isoforms (HAS1, 2 and 3) in mammals. The HASs have different tissue expression patterns and function, indicating that synthesis of HA and formation of the HA matrix may be regulated by various factors. The HA matrix has an important role in renal water handling and the production of a concentrated urine. We investigated the distribution of HA and the expression of HAS1, HAS2 and HAS3 mRNAs in the kidney of the Spinifex hopping mouse, Notomys alexis, a native Australian desert rodent that is reported to produce the most concentrated urine of any mammal. After periods of three, seven and fourteen days of water deprivation, the distribution of renal HA changed considerably, and there was a general down-regulation of HAS mRNA expression. It is proposed that the regulation of HA synthesis by the different HAS isoforms during water deprivation in N. alexis, could be influenced by the molecular mass of the HA chains produced by each isoform, followed by the rate at which the individual HAS produces HA.
Resumo:
Purpose. This study explored the effectiveness of the Gudjonsson Suggestibility Scale for Children, version 2 in predicting the tendency of older school-aged children (with and without intellectual disabilities) to generate errors in an independent suggestibility paradigm.
Method. Sixty-nine children with an intellectual disability (aged 9-14 years) and 50 mainstream children matched for chronological age participated in a 30-minute magic show that was staged at their school. Three days later, the children participated in a separate biasing interview that provided seven true and seven false details about the magic show. The following day, the children participated in a second interview where they were required to recall the magic show in their own words and answer a series of cued-recall questions. Between 1 and 2 weeks later, the children were administered the Gudjonsson Suggestibility Scale-2 (GSS-2).
Results. While there was no significant association between performance on the GSS-2 and the independent suggestibility paradigm for the children with an intellectual disability, the chronological age-matched children's yield scores predicted their reporting of both false-new details and false-interviewer suggestions for the independent event.
Conclusion. When predicting children's recall of false details, the GSS-2 appears to be more useful with mainstream school-aged children compared with children who have an intellectual disability.
Resumo:
The principal aim of this study is to examine the relationship between the cultural background of students and their learning approaches in a tertiary accounting program. While prior research in this area has more generally focused on the investigation of the learning approaches of accounting students, there appears to have been little investigation into the learning approaches of students from different cultures who are studying together at the same institution. The paper presents the results of a study of 550 students enrolled in an undergraduate accounting program at a multi-campus Victorian university where learning approaches and cultural background variables were investigated together with other background variables such as gender and age.
The findings extend prior research on the impact cultural factors may have on the learning approaches of accounting students and also assists in clarifying the relationship between memorisation in the process of learning given the diverse ways that students from different cultures study accounting.
Resumo:
Information technology has transformed the “heartland” of education around the world. Classrooms are global, students international, but traditional methods and their adjacent challenges persist or are exacerbated in online schoolhouses. There is reason to believe that team performance of online students completing team projects can be significantly improved by the active participation of a facilitator. What could explain such improvement? Given the communication barriers that learners can experience using e-learning technologies, the skill of a teacher at facilitating an understanding of e-collaboration and the prescient need to facilitate collaborative skills at all times is essential to a successful educational result. There may also be generational learning style issues to consider. One practical, proven tool is progress reporting. This paper reviews the literature and reflects on author experiences in the online education of Management students at universities in the United States and Australia to draw theoretical connections with communication, leadership, and punctuated equilibrium relevant to contemporary educational practice. The implications of effective facilitation of student teams for Management education and management of student performance are explored.
Resumo:
As a result of recent increases in fuel prices and the growing number of accident fatalities, the two major concerns of the automotive industry and their customers are now occupant safety and fuel economy {1, 2]. Increasing the amount of energy and optimizing the manner in which energy is absorbed within vehicle crush zones can improve occupant survivability in the event of a crash, while fuel economy is improved through a reduction in weight. Axial crush tests were conducted on tubular specimens of Carbon/Epoxy (Toray T700/G83C) and Glass/Polypropylene (Twintex). This paper presents results from the tests conducted at quasi-static rates at Deakin Unniversity, Victoria Australia, and intermediate rate tests performed at the Oak Ridge National Laboratory, Tennessee USA. The quasi-static tests were conducted at 10mm/min (1.67x10-4m/s) using 5 different forms of initiation. Tests at intermediate rates were performed at speeds of 0.25m/s, 0.5m/s, 0.75m/s 1m/s, 2m/s and 4m/s. Quasi-static tests of tubular specimens showed high specific energy absorption (SEA) values with 86 kJ/kg for Carbon/Epoxy specimens. The SEA of the Glass/Polypropylene specimens was measured to be 29 kJ/kg. Results from the intermediate test rates showed that SEA values did not fall below 55kJ/kg for carbon specimens or 35kJ/kg for the Glass/Polypropylene specimens. When compared with typical steel and aluminium, SEA values of 15 kJ/kg and 30kJ/kg respectively, the benefits of using composite materials in crash structures is apparent.
Resumo:
The purpose of this paper is to present and analyse a case example of the development and implementation of a digital learnmg object in context with academic literature in the field. The paper's content describes the creation of a multimedia learning object from conception in 2004 to completion m 2006. Provided is the rationale and outcome of a strategically funded University project aimed at illuminating an industrial case study of good management and communication practices for use in classrooms throughout the entire university. This paper is intended to act as a guide for others. Our experience as academics in successful dialogue With educational technologists will inspire and inform those embarking on similar projects, and aspects of it will generalise to development and implementation Issues for other kinds of learning objects.
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Background: Walking is integral to strategies to promote physical activity. We identified socio-demographic variations in walking for transport, and for recreation or exercise. Methods: Representative population data (n = 3392) from Australia were collected using computer assisted telephone interviewing, to examine adults’ participation in moderate- or brisk-paced walking for transport and walking for recreation or exercise; walking “sufficient” to meet the current public health guideline (> 150 min/wk); and, the contributions of total walking to meeting the guideline for total physical activity. Results: Rates of sufficient walking for transport (10% for men, 9% for women) were lower than those for walking for recreation or exercise (14% for both genders). Few socio-demographic differences emerged. Men over age 60 y were significantly less likely (OR = 0.40) to walk for transport; men age 45 to 59 y were more likely (OR = 1.56) to walk for recreation or exercise. Walking contributed more toward meeting the current public health guideline among women (15% to 21%) than among men (6% to 8%). Conclusions: There is potential for socially equitable increases in participation, through a focus on both walking for transport and on walking for recreation or exercise; attention to gender differences would be helpful.
Resumo:
There have been few longitudinal studies of quality of life in patients with all stages of lung cancer, particularly those that have included measures of utility. The purpose of this study was to examine the psychometric properties of the Assessment of Quality of Life instrument (AQoL) in patients with lung cancer. The AQoL is a health-related quality of life questionnaire and provides a descriptive system for a multi-attribute utility instrument (MAU), so that scores can be used in cost-utility evaluations. In the present study the reliability (internal consistency) of the AQoL was examined and the concurrent validity was assessed using the Medical Outcomes 36-item Short Form Health Survey (SF-36) as the comparator instrument. The sensitivity to different health states of the AQoL and the responsiveness to change over time was also examined. A prospective, non-experimental cohort study was undertaken. Ninety-two participants with all stages of lung cancer were recruited from a tertiary multi-disciplinary lung cancer clinic. Ninety participants had non-small cell lung cancer (NSCLC) and two had limited stage small cell lung cancer. The AQOL and SF-36 surveys were administered concurrently at baseline. In patients with NSCLC the surveys were then repeated 3 and 6 months later. Correlations between the baseline AQoL summary scales and SF-36 summary scales support the divergent and convergent validity of the AQoL. Reliability was also found to be sufficient (Cronbach's Alpha = 0.76). In addition, in patients with inoperable NSCLC, baseline AQoL scores were found to be predictive of survival at 6 months in Cox proportional hazards multivariate analysis. However, the physical components summary score of the SF-36 was more sensitive to differences in health states between patients with different stages of NSCLC at 6 months of follow-up and more responsive to change over time in both operable and inoperable patients with NSCLC than the AQoL. The findings support the construct validity and reliability of the AQoL in this population. However, there remains some uncertainty about whether the AQoL has sufficient sensitivity to different health states in this population. Further studies using other MAU instruments may determine whether alternative instruments are more sensitive to different health states in individuals with lung cancer.
Resumo:
The current system of controlling oil spills involves a complex relationship of international, federal and state law, which has not proven to be very effective. The multiple layers of regulation often leave shipowners unsure of the laws facing them. Furthemore, nations have had difficulty enforcing these legal requirements. This thesis deals with the role marine insurance can play within the existing system of legislation to provide a strong preventative influence that is simple and cost-effective to enforce. In principle, insurance has two ways of enforcing higher safety standards and limiting the risk of an accident occurring. The first is through the use of insurance premiums that are based on the level of care taken by the insured. This means that a person engaging in riskier behavior faces a higher insurance premium, because their actions increase the probability of an accident occurring. The second method, available to the insurer, is collectively known as cancellation provisions or underwriting clauses. These are clauses written into an insurance contract that invalidates the agreement when certain conditions are not met by the insured The problem has been that obtaining information about the behavior of an insured party requires monitoring and that incurs a cost to the insurer. The application of these principles proves to be a more complicated matter. The modern marine insurance industry is a complicated system of multiple contracts, through different insurers, that covers the many facets of oil transportation. Their business practices have resulted in policy packages that cross the neat bounds of individual, specific insurance coverage. This paper shows that insurance can improve safety standards in three general areas -crew training, hull and equipment construction and maintenance, and routing schemes and exclusionary zones. With crew, hull and equipment, underwriting clauses can be used to ensure that minimum standards are met by the insured. Premiums can then be structured to reflect the additional care taken by the insured above and beyond these minimum standards. Routing schemes are traffic flow systems applied to congested waterways, such as the entrance to New York harbor. Using natural obstacles or manmade dividers, ships are separated into two lanes of opposing traffic, similar to a road. Exclusionary zones are marine areas designated off limits to tanker traffic either because of a sensitive ecosystem or because local knowledge is required of the region to ensure safe navigation. Underwriting clauses can be used to nullify an insurance contract when a tanker is not in compliance with established exclusionary zones or routing schemes.
Resumo:
Introduction:
Low dose spiral computed tomography (CT) is a sensitive screening tool for lung cancer that is currently being evaluated in both non-randomised studies and randomised controlled trials.
Methods:
We conducted a quantitative decision analysis using a Markov model to determine whether, in the Australian setting, offering spiral CT screening for lung cancer to high risk individuals would be cost-effective compared with current practice. This exploratory analysis was undertaken predominantly from the perspective of the government as third-party funder. In the base-case analysis, the costs and health outcomes (life-years saved and quality-adjusted life years) were calculated in a hypothetical cohort of 10,000 male current smokers for two alternatives: (1) screen for lung cancer with annual CT for 5 years starting at age 60 year and treat those diagnosed with cancer or (2) no screening and treat only those who present with symptomatic cancer.
Results:
For male smokers aged 60–64 years, with an annual incidence of lung cancer of 552 per 100,000, the incremental cost-effectiveness ratio was $57,325 per life-year saved and $105,090 per QALY saved. For females aged 60–64 years with the same annual incidence of lung cancer, the cost-effectiveness ratio was $51,001 per life-year saved and $88,583 per QALY saved. The model was used to examine the relationship between efficacy in terms of the expected reduction in lung cancer mortality at 7 years and cost-effectiveness. In the base-case analysis lung cancer mortality was reduced by 27% and all cause mortality by 2.1%. Changes in the estimated proportion of stage I cancers detected by screening had the greatest impact on the efficacy of the intervention and the cost-effectiveness. The results were also sensitive to assumptions about the test performance characteristics of CT scanning, the proportion of lung cancer cases overdiagnosed by screening, intervention rates for benign disease, the discount rate, the cost of CT, the quality of life in individuals with early stage screen-detected cancer and disutility associated with false positive diagnoses. Given current knowledge and practice, even under favourable assumptions, reductions in lung cancer mortality of less than 20% are unlikely to be cost-effective, using a value of $50,000 per life-year saved as the threshold to define a “cost-effective” intervention.
Conclusion:
The most feasible scenario under which CT screening for lung cancer could be cost-effective would be if very high-risk individuals are targeted and screening is either highly effective or CT screening costs fall substantially.
Resumo:
We model and empirically test the link between income inequality and trade liberalization. We consider a society in which a median voter (MV) will make the decision as to whether the country should switch from its current regime of import substitution (IS) (which protects agriculture) to export promotion (EP). Liberalization entails starting importing the agricultural good and specializing in and exporting the manufacturing good. This will require transferring labor to manufacturing. We find that if MV is a worker, the IS-EP switch will take place regardless. If MV is a farmer, the switch will take place given (1) the relative productivity of an ex-farmer and worker in manufacturing,ß is high, and (2) the society’s tastes for agricultural goods, α, are not as strong as those for manufacturing goods. We also find that, following a switch, the income distribution too will improve if α is low and ß is high. In our empirical analysis, we find the endogenous inflection points of α and ß in our sample, at which the direction of change in income distribution alters its sign. Our results also show in a very robust fashion that, EP regimes - on average and with the presence of certain control variables - have better income distributions than IS regimes. This implies that mostly “right” countries have made the switch.