The family costs of attending hospital outpatient appointments via videoconference and in person

We compared the costs incurred by families attending outpatient appointments at the Royal Children's Hospital (RCH) in Brisbane with those incurred by families who had a consultation via videoconference in their regional area. In each category 200 families were interviewed. The median time spent travelling for videoconferences was 30 min compared with 80 min for face-to-face appointments. Families interviewed in the outpatient department had travelled a median distance of 70 km, while those who had a videoconference at the local hospital had travelled only 20 km. It cost these families much more to attend an appointment at the RCH than to attend a videoconference. Ninety-six per cent of families (193) reported at least one of the following types of expense: 150 families had expenses related to parking (median A$10), 156 had fuel expenses (median A$10) and 122 reported costs related to meals purchased at the RCH (median A$10). Only 21 families who had their appointment via local videoconference reported any additional costs. Specialist appointments via videoconference were a more convenient and cheaper option for families living in regional areas of Queensland than the conventional method of attending outpatient appointments at the specialist hospital in Brisbane.

Costs of adjustment to climate change

The present paper argues that the costs of climate change are primarily adjustment costs. The central result is that climate change will reduce welfare whenever it occurs more rapidly than the rate at which capital stocks (interpreted broadly to include natural resource stocks) would naturally adjust through market processes. The costs of climate change can be large even when lands are close to their climatic optimum, or evenly distributed both above and below that optimum.

Use of a probabilistic neural network to reduce costs of selecting construction rock

Rocks used as construction aggregate in temperate climates deteriorate to differing degrees because of repeated freezing and thawing. The magnitude of the deterioration depends on the rock's properties. Aggregate, including crushed carbonate rock, is required to have minimum geotechnical qualities before it can be used in asphalt and concrete. In order to reduce chances of premature and expensive repairs, extensive freeze-thaw tests are conducted on potential construction rocks. These tests typically involve 300 freeze-thaw cycles and can take four to five months to complete. Less time consuming tests that (1) predict durability as well as the extended freeze-thaw test or that (2) reduce the number of rocks subject to the extended test, could save considerable amounts of money. Here we use a probabilistic neural network to try and predict durability as determined by the freeze-thaw test using four rock properties measured on 843 limestone samples from the Kansas Department of Transportation. Modified freeze-thaw tests and less time consuming specific gravity (dry), specific gravity (saturated), and modified absorption tests were conducted on each sample. Durability factors of 95 or more as determined from the extensive freeze-thaw tests are viewed as acceptable—rocks with values below 95 are rejected. If only the modified freeze-thaw test is used to predict which rocks are acceptable, about 45% are misclassified. When 421 randomly selected samples and all four standardized and scaled variables were used to train aprobabilistic neural network, the rate of misclassification of 422 independent validation samples dropped to 28%. The network was trained so that each class (group) and each variable had its own coefficient (sigma). In an attempt to reduce errors further, an additional class was added to the training data to predict durability values greater than 84 and less than 98, resulting in only 11% of the samples misclassified. About 43% of the test data was classed by the neural net into the middle group—these rocks should be subject to full freeze-thaw tests. Thus, use of the probabilistic neural network would meanthat the extended test would only need be applied to 43% of the samples, and 11% of the rocks classed as acceptable would fail early.

Two knees or not two knees? Patient costs and outcomes following bilateral and unilateral total knee joint replacement surgery for OA

Aims: This study aims to address medical and non-medical direct costs and health outcomes of bilateral and unilateral total knee replacement from the patients' perspective during the first year post-surgery. Methods: Osteoarthritis patients undergoing primary unilateral total knee or bilateral total knee replacement (TKR) surgery at three Sydney hospitals were eligible. Patients completed questionnaires pre-operatively to record expenses during the previous three months and health status immediately prior to surgery. Patients then maintained detailed prospective cost diaries and completed SF-36 and WOMAC Index each three months for the first post-operative year. Results: Pre-operatively, no significant differences in health status were found between patients undergoing unilateral TKR and bilateral TKR. Both unilateral and bilateral TKR patients showed improvements in pain, stiffness and function from pre-surgery to 12 months post-surgery. Patients who had bilateral TKR spent an average of 12.3 days in acute hospital and patients who had unilateral TKR 13.6 days. Totally uncemented prostheses were used in 6% of unilateral replacements and 48% of bilateral replacements. In hospital, patients who had bilateral TKR experienced significantly more complications, mainly thromboembolic, than patients who had unilateral TKR. Regression analysis showed that for every one point increase in the pre-operative SF-36 physical score (i.e. improving physical status) out-of-pocket costs decreased by 94%. Out-of-pocket costs for female patients were 3.3 times greater than for males. Conclusion: Patients undergoing bilateral TKR and unilateral TKR had a similar length of stay in hospital and similar out-of-pocket expenditures. Bilateral replacement patients reported better physical function and general health with fewer health care visits one year post procedure. Patients requiring bilateral TKR have some additional information to aid their decision making. While their risk of peri-operative complications is higher, they have an excellent chance of good health outcomes at 12 months and are not going to be doubly 'out-of-pocket' for the experience. (C) 2004 OsteoArthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

A note on execution costs for stock index futures: Information versus liquidity effects

This paper examines execution costs and the impact of trade size for stock index futures using price-volume transaction data from the London International Financial Futures and Options Exchange. Consistent with Subrahmanyam [Rev. Financ. Stud. 4 (1991) 11] we find that effective half spreads in the stock index futures market are small compared to stock markets, and that trades in stock index futures have only a small permanent price impact. This result is important as it helps to better understand the success of equity index products such as index futures and Exchange Traded Funds. We also find that there is no asymmetry in the post-trade price reaction between purchases and sales for stock index futures across various trade sizes. This result is consistent with the conjecture in Chan and Lakonishok [J. Financ. Econ. 33 (1993) 173] that the asymmetry surrounding block trades in stock markets is due to the high cost of short selling and the general reluctance of traders to short sell on stock markets. (C) 2004 Elsevier B.V. All rights reserved.

Costs increase as ritualized fighting progresses within and between phases in the sierra dome spider, Neriene litigiosa

Magnitudes and patterns of energy expenditure in animal contests are seldom measured, but can be critical for predicting contest dynamics and understanding the evolution of ritualized fighting behaviour. In the sierra dome spider, males compete for sexual access to females and their webs. They show three distinct phases of fighting behaviour, escalating from ritualized noncontact display (phase 1) to cooperative wrestling (phase 2), and finally to unritualized, potentially fatal fighting (phase 3). Using CO2 respirometry, we estimated energetic costs of male-male combat in terms of mean and maximum metabolic rates and the rate of increase in energy expenditure. We also investigated the energetic consequences of age and body mass, and compared fighting metabolism to metabolism during courtship. All three phases involved mean energy expenditures well above resting metabolic rate (3.5 X, 7.4 X and 11.5 X). Both mean and maximum energy expenditure became substantially greater as fights escalated through successive phases. The rates of increase in energy use during phases 2 and 3 were much higher than in phase 1. In addition, age and body mass affected contest energetics. These results are consistent with a basic prediction of evolutionarily stable strategy contest models, that sequences of agonistic behaviours should be organized into phases of escalating energetic costs. Finally, higher energetic costs of escalated fighting compared to courtship provide a rationale for first-male sperm precedence in this spider species. (C) 2004 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.