Evaluation of pollutant exposure using virtual walkers and large-eddy simulation: Application to an idealised urban neighbourhood.

Urban air quality studies have primarily focused on pollutant dispersion; however, spatial or temporal concentrations collected at discretely distributed grid points (or fixed receptors) do not reflect the actual pollutant exposure of pedestrians. Using large-eddy simulation (LES) with virtual walkers implemented, this study investigates pollutant exposure of walking agents (or moving receptors) in an urban turbulent boundary-layer flow developed over an aligned building array under the influence of different wind directions. The spatial variability of the exposure risks are found to be better captured by the moving receptors than the fixed receptors along the same agent walking tracks. We demonstrate that the actual exposure can differ significantly from results interpreted from data recorded by the fixed receptors (corresponding to Eulerian estimates) and show that large discrepancies occur in avenues near the source, wherein dispersion of the point release has not occurred on larger spatiotemporal scales. In most scenarios, optimal evacuation routes are shown to be ones that deviate as much as possible from the dominant wind direction; however, one needs to decide the priority of moving to further avenues first or immediately adjusting the walking direction. The results should serve as a useful baseline reference for environmental health impact assessment and evacuation route planning against hazardous releases of air pollutants in more complex urban environments.

Hypercalcemic complication in patients with oral squamous cell carcinoma.

Hypercalcemia is one of the metabolic complications associated with cancer. To assess the frequency of hypercalcemia in patients with squamous cell carcinoma (SCC), 242 patients who were evaluated as having SCC in the oral cavity between July 1995 and June 2001 were investigated. All patients were periodically monitored for their serum level of calcium (Ca). Hypercalcemia was defined as a serum Ca concentration higher than 11 mg/dl. By this definition, hypercalcemia was detected in 12 of the 242 patients (5.0%). All 12 patients were at an advanced stage of oral SCC. In these 12 patients, the serum level of parathyroid hormone-related protein (PTH-rP) was also significantly elevated. Therefore, we diagnosed these diseases as humoral hypercalcemia of malignancy (HHM). Moreover, we studied the efficacy of anti-hypercalcemic therapy on the quality of life (QOL). The European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30 was used for estimation of QOL. The patients with HHM who were administrated drugs such as bisphosphonate and calcitonin showed a reduction in their Ca and PTH-rP levels, and the six of ten EORTC QLQ-C30 subscales (emotional functioning, cognitive functioning, fatigue, dyspnoea, nausea/vomiting and appetite loss) were also improved after the anti-hypercalcemic therapy. However, these suppressive effects were temporary. The median survival time after the diagnosis of HHM was only 54.9+/-18.3 days (range 27-86 days). Therefore, HHM in SCC appears to be an ominous prognostic sign. Although anti-hypercalcemic therapy has a palliative role, the patients may be in less discomfort during the terminal stage of their illness.

Remembrances of the war and the bomb.

KIE: Takemi, former president of the Japan Medical Association and a student of nuclear physics in 1945, briefly recounts his role in the events subsequent to the atomic bombing of Hiroshima. He now believes that the atomic bomb saved Japan from the military's plan to sacrifice the entire nation rather than surrender. Takemi concludes by urging Japanese and American physicians to join together to prevent the use of nuclear weapons.^ieng