Simulation of the load-unload response ratio and critical sensitivity in the lattice solid model

The Load-Unload Response Ratio (LURR) method is an intermediate-term earthquake prediction approach that has shown considerable promise. It involves calculating the ratio of a specified energy release measure during loading and unloading where loading and unloading periods are determined from the earth tide induced perturbations in the Coulomb Failure Stress on optimally oriented faults. In the lead-up to large earthquakes, high LURR values are frequently observed a few months or years prior to the event. These signals may have a similar origin to the observed accelerating seismic moment release (AMR) prior to many large earthquakes or may be due to critical sensitivity of the crust when a large earthquake is imminent. As a first step towards studying the underlying physical mechanism for the LURR observations, numerical studies are conducted using the particle based lattice solid model (LSM) to determine whether LURR observations can be reproduced. The model is initialized as a heterogeneous 2-D block made up of random-sized particles bonded by elastic-brittle links. The system is subjected to uniaxial compression from rigid driving plates on the upper and lower edges of the model. Experiments are conducted using both strain and stress control to load the plates. A sinusoidal stress perturbation is added to the gradual compressional loading to simulate loading and unloading cycles and LURR is calculated. The results reproduce signals similar to those observed in earthquake prediction practice with a high LURR value followed by a sudden drop prior to macroscopic failure of the sample. The results suggest that LURR provides a good predictor for catastrophic failure in elastic-brittle systems and motivate further research to study the underlying physical mechanisms and statistical properties of high LURR values. The results provide encouragement for earthquake prediction research and the use of advanced simulation models to probe the physics of earthquakes.

Diabetes detection in Australian general practice: a comparison of diagnostic criteria

Objectives: To study the influence of different diagnostic criteria on the prevalence of diabetes mellitus and characteristics of those diagnosed. Design and setting: Retrospective analysis of data from the general-practice-based Australian Diabetes Screening Study (January 1994 to June 1995). Participants: 5911 people with no previous diagnosis of diabetes, two or more symptoms or risk factors for diabetes, a random venous plasma glucose (PG) level > 5.5 mmol/L and a subsequent oral glucose tolerance test (OGTT) result. Main outcome measure: Prevalence of undiagnosed diabetes based on each of three sets of criteria: 1997 criteria of the American Diabetes Association (ADA), 1996 two-step screening strategy of the Australian Diabetes Society (ADS) (modified according to ADA recommendations about lowered diagnostic fasting PG level), and 1999 definition of the World Health Organization (WHO). Results: Prevalence estimates for undiagnosed diabetes using the American (ADA), Australian (ADS) and WHO criteria (95% CI) were 9.4% (8.7%-10.1%), 16.0% (15.3%-16.7%) and 18.1% (17.1%-19.1%), respectively. People diagnosed with diabetes by fasting PG level (common to all sets of criteria) were more likely to be male and younger than those diagnosed only by 2 h glucose challenge PG level (Australian and WHO criteria only). The Australian (ADS) stepwise screening strategy detected 88% of those who met the WHO criteria for diabetes, including about three-quarters of those with isolated post-challenge hyperglycaemia. Conclusion: The WHO criteria (which include an OGTT result) are preferable to the American (ADA) criteria (which rely totally on fasting PG level), as the latter underestimated the prevalence of undiagnosed diabetes by almost a half. The Australian (ADS) strategy identified most of those diagnosed with diabetes by WHO criteria.

Bridging the gap between different statistical approaches: An integrated framework for modelling

This paper proposes a template for modelling complex datasets that integrates traditional statistical modelling approaches with more recent advances in statistics and modelling through an exploratory framework. Our approach builds on the well-known and long standing traditional idea of 'good practice in statistics' by establishing a comprehensive framework for modelling that focuses on exploration, prediction, interpretation and reliability assessment, a relatively new idea that allows individual assessment of predictions. The integrated framework we present comprises two stages. The first involves the use of exploratory methods to help visually understand the data and identify a parsimonious set of explanatory variables. The second encompasses a two step modelling process, where the use of non-parametric methods such as decision trees and generalized additive models are promoted to identify important variables and their modelling relationship with the response before a final predictive model is considered. We focus on fitting the predictive model using parametric, non-parametric and Bayesian approaches. This paper is motivated by a medical problem where interest focuses on developing a risk stratification system for morbidity of 1,710 cardiac patients given a suite of demographic, clinical and preoperative variables. Although the methods we use are applied specifically to this case study, these methods can be applied across any field, irrespective of the type of response.

Neonatal respiratory therapy in the new millennium: Does clinical practice reflect scientific evidence?

Respiratory therapy has historically been considered the primary role of the physiotherapist in neonatal intensive care in Australia. In 2001 a survey was undertaken of all level three neonatal intensive care units in Australia to determine the role of the physiotherapist and of respiratory therapy in clinical practice. It appears that respiratory therapy is provided infrequently, with the number of infants treated per month ranging from 0 to 10 in 15 of the 20 units who provide respiratory therapy, regardless of therapist availability. The median number of respiratory treatments per month during the week was three, and on weekends it was one. Respiratory therapy was carried out by physiotherapists and nurses in 54.6% of units, by physiotherapists only in 36.4% of units, and by nurses only in the remaining 9% of units surveyed. There was also a diminution of the role of respiratory therapy in the extubation of premature infants. A review of the literature shows that overall the use of respiratory therapy reflects current evidence. The question remains whether it is possible to maintain the competency of staff and justify the cost of training in the current healthcare economic climate. It seems probable that the future role of physiotherapists in neonatal intensive care unit may be in the facilitation of optimal neurological development of surviving very low birth weight infants.

Perceptions of evidence-based practice: A survey of Australian occupational therapists

Evidence-based practice (EBP) requires clinicians to access, appraise and integrate research literature with clinical experience and clients' perspectives. Currently, little is known about occupational therapists' attitudes to EBP, their perception of implementation barriers or their educational needs. A questionnaire reflecting these issues was sent to a proportionate random sample of 1491 members of the national professional occupational therapy association, OT AUSTRALIA. The questionnaire was completed by 649 (44%) participants. Occupational therapists were positive about EBP with most (96%) agreeing that EBP is important to occupational therapy. Although 56% used research to make clinical decisions, more relied on clinical experience (96%), information from continuing education (82%) and colleagues (80%). Lack of time, evidence and skills were identified as the main barriers to the implementation of EBP. Over half (52%) expressed strong interest in EBP skills training, and most (80%) indicated an interest in the availability of brief summaries of evidence. Targeted educational initiatives, resources and systems are needed to support EBP in occupational therapy.

Treatment approaches for clients with a stroke-affected upper limb: Are we following evidence-based practice?

Stroke rehabilitation is an area of practice that many occupational therapists encounter during their career. The literature promotes a wide range of management techniques and support devices for people who have a stroke-affected upper limb, but little is known about the validity of those that occupational therapists actually use in practice. A questionnaire was sent to occupational therapists working in Queensland and northern New South Wales facilities (n = 35), in which adults with a stroke were likely to be treated. Eighteen respondents answered questions about the management techniques and support devices used in their facility, and their perception of the benefit of these devices in the reduction of hemiplegic shoulder pain. Results are discussed with reference to evidence-based practice and indicate an urgent need for the collation and dissemination of the best current evidence available for the management techniques and support devices used in this area, as well as further research to extend this evidence.