Experimental evidence for extreme dispersal limitation in tropical forest birds.

Movements of organisms between habitat remnants can affect metapopulation structure, community assembly dynamics, gene flow and conservation strategy. In the tropical landscapes that support the majority of global biodiversity and where forest fragmentation is accelerating, there is particular urgency to understand how dispersal across habitats mediates the demography, distribution and differentiation of organisms. By employing unique dispersal challenge experiments coupled with exhaustive inventories of birds in a Panamanian lacustrine archipelago, we show that the ability to fly even short distances (< 100 m) between habitat fragments varies dramatically and consistently among species of forest birds, and that this variation correlates strongly with species' extinction histories and current distributions across the archipelago. This extreme variation in flight capability indicates that species' persistence in isolated forest remnants will be differentially mediated by their respective dispersal abilities, and that corridors connecting such fragments will be essential for the maintenance of avian diversity in fragmented tropical landscapes.

Constitutive immune defences correlate with life-history variables in tropical birds.

1. It has been suggested that immune defences are shaped by life history and ecology, but few general patterns have been described across species. We hypothesized that 'fast' life-history traits (e.g. short development times, large clutch sizes) would be associated with developmentally inexpensive immune defences, minimizing the resource demands of young animals' immune systems during periods of rapid growth. Conversely, 'slow' life histories should be associated with well developed antibody-mediated defences, which are developmentally costly. 2. We therefore predicted that 'fast-living' species would exhibit higher levels of complement proteins, a component of non-specific innate defence, but lower levels of constitutive ('natural') antibodies. Additionally, we predicted that constitutive immune defences in general would be higher in species with ecological characteristics that might increase exposure to pathogens, such as open nests, omnivorous diets, gregariousness, and closed forested habitat. 3. Across 70 Neotropical bird species, we found a strongly positive relationship between incubation period and natural antibody levels in adult birds, suggesting that longer developmental times might allow the production of a more diverse and/or more reactive adaptive immune system. Complement activity was positively, although weakly, correlated with clutch size, providing some support for the hypothesis that faster-living species rely more on innate defences, such as complement. Unexpectedly, solitary species had higher natural antibody titres than species that frequently join flocks. 4. Our results suggest that, despite probably widespread differences in the intensity and diversity of pathogen exposure, species-level variation in constitutive immune defences is understandable within the context of life-history theory.

Post-wildfire logging hinders regeneration and increases fire risk.

We present data from a study of early conifer regeneration and fuel loads after the 2002 Biscuit Fire, Oregon, USA, with and without postfire logging. Natural conifer regeneration was abundant after the high-severity fire. Postfire logging reduced median regeneration density by 71%, significantly increased downed woody fuels, and thus increased short-term fire risk. Additional reduction of fuels is necessary for effective mitigation of fire risk. Postfire logging can be counterproductive to the goals of forest regeneration and fuel reduction.

Technician, friend, detective, and healer: family physicians' responses to emotional distress.

OBJECTIVE: We sought to develop a typology of physicians' responses to patients' expressed mental health needs to better understand the gap between idealized practice and actual care for emotional distress and mental health problems. STUDY DESIGN: We used a multimethod comparative case study design of 18 family practices that included detailed descriptive field notes from direct observation of 1637 outpatient visits. An immersion/crystallization approach was used to explore physicians' responses to emotional distress and apparent mental health issues. POPULATION: A total of 379 outpatient encounters were reviewed from a purposeful sample of 13 family physicians from the 57 clinicians observed. OUTCOMES MEASURED: Descriptive field notes of outpatient visits were examined for emotional content and physicians' responses to emotional distress. RESULTS: Analyses revealed a 3-phase process by which physicians responded to emotional distress: recognition, triage, and management. The analyses also uncovered a 4-quadrant typology of management based on the physician's philosophy (biomedical vs holistic) and skill level (basic vs more advanced). CONCLUSIONS: Physicians appear to manage mental health issues by using 1 of 4 approaches based on their philosophy and core set of skills. Physician education and practice improvement should be tailored to build on physicians' natural philosophical proclivity and psychosocial skills.

Calibration of SeaWiFS. II. Vicarious techniques.

We present an overview of the vicarious calibration of the Sea-Viewing Wide Field-of-view Sensor (SeaWiFS). This program has three components: the calibration of the near-infrared bands so that the atmospheric correction algorithm retrieves the optical properties of maritime aerosols in the open ocean; the calibration of the visible bands against in-water measurements from the Marine Optical Buoy (MOBY); and a calibration-verification program that uses comparisons between SeaWiFS retrievals and globally distributed in situ measurements of water-leaving radiances. This paper describes the procedures as implemented for the third reprocessing of the SeaWiFS global mission data set. The uncertainty in the near-infrared vicarious gain is 0.9%. The uncertainties in the visible-band vicarious gains are 0.3%, corresponding to uncertainties in the water-leaving radiances of approximately 3%. The means of the SeaWiFS/in situ matchup ratios for water-leaving radiances are typically within 5% of unity in Case 1 waters, while chlorophyll a ratios are within 1% of unity. SeaWiFS is the first ocean-color mission to use an extensive and ongoing prelaunch and postlaunch calibration program, and the matchup results demonstrate the benefits of a comprehensive approach.

Acute nongonococcal infectious arthritis. Evaluation of risk factors, therapy, and outcome.

A retrospective analysis of 71 nongonococcal joint infections in 63 patients is reported. Staphylococcus aureus was isolated from 59% of the patients. Five patients died as a result of infections. The outcome in Gram-negative joint infections was similar to the overall outcome in the entire series of patients. All 11 joints with infected prostheses ultimately required removal of the prostheses. All patients were treated with appropriate parenteral antibiotics, and surgical intervention was used in 40 joints. Six patients underwent surgical treatment because of inability to sterilize the joint with antibiotics and because of repeated joint aspirations. The outcome with surgical intervention was good only in patients younger than 16 years of ages. Medical therapy (parenteral antibiotics and frequent joint aspirations) led to good results in 74% of the patients. Outcome of joint infection was also influenced by factors which contribute to impaired host resistance.