Increased environmental gamma-ray dose rate during precipitation: a strong correlation with contributing air mass.

It has long been observed that the environmental gamma-ray dose rate increases noticeably during precipitation intervals. This increase, due to the presence of radon progeny in the rain droplets (or snow flakes), can affect the reliability of the monitoring of artificial radioactivity and long term estimates of exposure to ambient natural radionuclides in surveillance network. Predicting the amplitude of the dose increase has been shown to be surprisingly challenging. In this work, standard air mass back trajectory analysis is used to show that the amplitude of the increase can be quantitatively linked to the history of the air mass where the precipitation is occurring. Furthermore, we show how back trajectory analysis, environmental gamma and rain data can be used to obtain estimations of relative radon emanation rates for locations far from the actual point of detection.

Measurement and modelling of radioxenon plumes in the Ottawa Valley.

Since 2001 a real-time radiation monitoring network of Canadian nuclear facilities and major population centres has been implemented for response to nuclear incidents including a possible terrorist attack. Unshielded NaI(Tl) spectroscopic detectors are employed to measure gamma radiation from airborne radioactivity and radioactivity deposited on the ground. These detectors are composed of a standard 3''x3'' cylindrical NaI(Tl) spectrometers with data storage and integrated telemetry. Some of the detectors have been deployed in the Ottawa Valley near Chalk River Laboratories and Ottawa, which has a complex radioxenon environment due to the proximity of nuclear power reactors, and medical isotope facilities. Although not a health threat, these releases have provided an opportunity for the Canadian Meteorological Centre and the Commissariat à l'Energie Atomique to validate their meteorological models. The meteorological models of the two organizations are in good agreement on the origin and the source terms of these releases.

Automated radioxenon monitoring for the comprehensive nuclear-test-ban treaty in two distinctive locations: Ottawa and Tahiti.

In preparation for verification of the Comprehensive Nuclear-Test-Ban-Treaty, automated radioxenon monitoring is performed in two distinctive environments: Ottawa and Tahiti. These sites are monitored with SPALAX (Systeme de Prelevement d'air Automatique en Ligne avec l'Analyse des radioXenons) technology, which automatically extracts radioxenon from the atmosphere and measures the activity concentrations of (131m,133m,133,135)Xe. The resulting isotopic concentrations can be useful to discern nuclear explosions from nuclear industry xenon emissions. Ambient radon background, which may adversely impact analyser sensitivity, is discussed. Upper concentration limits are reported for the apparently radioxenon free Tahiti environment. Ottawa has a complex radioxenon background due to proximity to nuclear reactors and medical isotope facilities. Meteorological models suggest that, depending on the wind direction, the radioxenon detected in Ottawa can be characteristic of the normal radioxenon background in the Eastern United States, Europe, and Japan or distinctive due to medical isotope production.

Can the confidence in long range atmospheric transport models be increased? The pan-european experience of ensemble.

Is atmospheric dispersion forecasting an important asset of the early-phase nuclear emergency response management? Is there a 'perfect atmospheric dispersion model'? Is there a way to make the results of dispersion models more reliable and trustworthy? While seeking to answer these questions the multi-model ensemble dispersion forecast system ENSEMBLE will be presented.

Pathogenesis and management of persistent postthoracotomy pain.

Persistent chest wall pain is common after thoracotomy and is usually caused by recurrence or progression of malignancy. It should prompt efforts to identify and treat the causative disease. A minority of patients experience persistent pain not related to neoplasm. This pain may last for years, but is usually not severe. A small subset of these patients experience persistent severe pain, which may be debilitating. The pain may be owing to various causes. Diagnosis and treatment should be individualized and directed toward the causes believed to be present. First-line pharmacologic therapies include NSAIDs, tricyclic antidepressants, antiepileptics, and low-dose opioids. Some patients require more sophisticated treatment from multidisciplinary pain-management clinics. This treatment may include nerve blocks, physical therapy, sympathectomy, cryoneurolysis, or long-term neuromodulation with epidural analgesia or spinal cord stimulation. Because of the severe pain these patients may experience and the difficulty and expense associated with treatment, prevention may be the best strategy for dealing with this problem. Recent laboratory and clinical studies indicate that minimizing perioperative pain can suppress certain alterations in the nervous system that may prevent the genesis and maintenance of chronically painful conditions. This suggests that strategies for avoiding PTPS may begin with aggressive perioperative anesthetic and analgesic techniques. More effective application of knowledge already available from laboratory studies awaits further clinical trials. New drugs such as NMDA inhibitors hold promise for more effective treatment in the future.

Postoperative pain management.

Distressing postoperative pain remains a prevalent problem. Poorly treated pain contributes to patient suffering and may prevent rapid recovery and rehabilitation. An understanding and application of the basic principles of pain management can provide adequate analgesia for the majority of postoperative patients. More advanced methods of pain control can allow excellent relief for virtually all patients but may require the presence of a dedicated pain management service. This article reviews the principles and practice of modern postoperative pain management.

Food deprivation and surfactant in adult rats.

We sought to determine if fasting (80% reduction of food intake for 72 h) diminishes airway or tissue disaturated phosphatidylcholine (DSPC) relative to alveolar surface area, or alters the lung response to overventilation. The lungs of fasted rats were lighter, but the size and recoil of saline-filled lungs, and the alveolar surface area of lungs fixed in glutaraldehyde, were the same in fed and fasted rats. In their airways fed rats had 0.32 +/- 0.01 microgram DSPC/cm2 of alveolar surface; fasted rats had 0.28 +/- 0.02 microgram DSPC/cm2 (P less than 0.05) (surface area determined at 20 cmH2O transpulmonary pressure). Fasted rats had 13% less tissue DSPC/cm2 alveolar surface than fed rats (P less than 0.01). After 1 h of mechanically produced overventilation the unequal amounts of airway, but not tissue, DSPC were eliminated and pulmonary compliance was similar in both groups. We conclude food reduction decreases the quantity of airway and tissue DSPC/cm2 of alveolar surface but does not increase lung recoil of spontaneously breathing rats (Gail, Massaro, and Massaro, J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 42: 88-92, 1977) or overventilated rats.