Crack depths in desiccating plastic concrete

The depths of cracks in desiccating plastic concrete are estimated by considering the effects of the suction (negative pore pressure) associated with desiccation and applying five failure models derived from fracture, theories combined with theories drawn from geotechnical engineering under the assumption that plastic concrete is a frictional particulate material. The estimated crack depths vary with the depth of desiccation, the suction profile, and a small number of material parameters that depend on the model adopted and are comparatively easy to estimate accurately. Four of the models predict excessively large crack depths. The fifth, however, predicts shallower crack depths that increase with the age of the concrete and are consistent with those of analogous desiccation cracks in coal mine tailings. It thus offers a relatively robust method of estimating the depth of desiccation cracks. Confirmation of this with data for plastic concrete is clearly desirable but not possible at present.

Towards structure-property-function relationships for eumelanin

We discuss recent progress towards the establishment of important structure-property-function relationships in eumelanins-key functional bio-macromolecular systems responsible for photoprotection and immune response in humans, and implicated in the development of melanoma skin cancer. We focus on the link between eumelanin's secondary structure and optical properties such as broad band UV-visible absorption and strong non-radiative relaxation; both key features of the photo-protective function. We emphasise the insights gained through a holistic approach combining optical spectroscopy with first principles quantum chemical calculations, and advance the hypothesis that the robust functionality characteristic of eumelanin is related to extreme chemical and structural disorder at the secondary level. This inherent disorder is a low cost natural resource, and it is interesting to speculate as to whether it may play a role in other functional bio-macromolecular systems.

Controlled trial of multidisciplinary care teams for acutely ill medical inpatients: enhanced multidisciplinary care

Background: Acute hospital general medicine services care for ageing complex patients, using the skills of a range of health-care providers. Evidence suggests that comprehensive early assessment and discharge planning may improve efficiency and outcomes of care in older medical patients. Aim: To enhance assessment, communication, care and discharge planning by restructuring consistent, patient-centred multidisciplinary teams in a general medicine service. Methods: Prospective controlled trial enrolling 1538 consecutive medical inpatients. Intervention units with additional allied health staff formed consistent multidisciplinary teams aligned with inpatient admitting units rather than wards; implemented improved communication processes for early information collection and sharing between disciplines; and specified shared explicit discharge goals. Control units continued traditional, referral-based multidisciplinary models with existing staffing levels. Results: Access to allied health services was significantly enhanced. There was a trend to reduced index length of stay in the intervention units (7.3 days vs 7.8 days in control units, P = 0.18), with no change in 6-month readmissions. in-hospital mortality was reduced from 6.4 to 3.9% (P = 0.03); less patients experienced functional decline in hospital (P = 0.04) and patients' ratings of health status improved (P = 0.02). Additional staffing costs were balanced by potential bed-day savings. Conclusion: This model of enhanced multidisciplinary inpatient care has provided sustainable efficiency gains for the hospital and improved patient outcomes.

Distillability of Werner states using entanglement witnesses and robust semidefinite programs

We use robust semidefinite programs and entanglement witnesses to study the distillability of Werner states. We perform exact numerical calculations that show two-undistillability in a region of the state space, which was previously conjectured to be undistillable. We also introduce bases that yield interesting expressions for the distillability witnesses and for a tensor product of Werner states with an arbitrary number of copies.

Anisotropy-based robust performance analysis of finite horizon linear discrete time varying systems

We consider a problem of robust performance analysis of linear discrete time varying systems on a bounded time interval. The system is represented in the state-space form. It is driven by a random input disturbance with imprecisely known probability distribution; this distributional uncertainty is described in terms of entropy. The worst-case performance of the system is quantified by its a-anisotropic norm. Computing the anisotropic norm is reduced to solving a set of difference Riccati and Lyapunov equations and a special form equation.

Hydrogen from coal: Production and utilisation technologies

Error condition detected Although coal may be viewed as a dirty fuel due to its high greenhouse emissions when combusted, a strong case can be made for coal to be a major world source of clean H-2 energy. Apart from the fact that resources of coal will outlast oil and natural gas by centuries, there is a shift towards developing environmentally benign coal technologies, which can lead to high energy conversion efficiencies and low air pollution emissions as compared to conventional coal fired power generation plant. There are currently several world research and industrial development projects in the areas of Integrated Gasification Combined Cycles (IGCC) and Integrated Gasification Fuel Cell (IGFC) systems. In such systems, there is a need to integrate complex unit operations including gasifiers, gas separation and cleaning units, water gas shift reactors, turbines, heat exchangers, steam generators and fuel cells. IGFC systems tested in the USA, Europe and Japan employing gasifiers (Texaco, Lurgi and Eagle) and fuel cells have resulted in energy conversions at efficiency of 47.5% (HHV) which is much higher than the 30-35% efficiency of conventional coal fired power generation. Solid oxide fuel cells (SOFC) and molten carbonate fuel cells (MCFC) are the front runners in energy production from coal gases. These fuel cells can operate at high temperatures and are robust to gas poisoning impurities. IGCC and IGFC technologies are expensive and currently economically uncompetitive as compared to established and mature power generation technology. However, further efficiency and technology improvements coupled with world pressures on limitation of greenhouse gases and other gaseous pollutants could make IGCC/IGFC technically and economically viable for hydrogen production and utilisation in clean and environmentally benign energy systems. (c) 2005 Elsevier B.V. All rights reserved.

General practice in Australia 2020: "robust and ready" or "rudderless and reeling"?

The future role and structure of Australian general practice remains uncertain, despite a decade of seemingly constant change following the release of the National Health Strategy papers. Some of the suggested change strategies (such as rural Practice Incentive Payments and practice accreditation) have been implemented; others (such as general practitioner involvement with area health authorities in delivering national goals and targets for communities) still await attention. An overarching vision for our health care system in 2020 and general practice's role within it are still to be clearly enunciated. Australia is at variance with other Western countries, such as the United Kingdom, Canada and New Zealand, which have spent significant time refocusing their health systems to deal with an ageing population with an increased burden of chronic disease. Health bureaucrats and governments need to invest strategically in operational primary care now. This will require the active commitment of general practice's national bodies to articulate and actively promote a shared vision for Australian general practice.