82 research outputs found
Systematic Conservation Planning in the Face of Climate Change: Bet-Hedging on the Columbia Plateau
Systematic conservation planning efforts typically focus on protecting current patterns of biodiversity. Climate change is poised to shift species distributions, reshuffle communities, and alter ecosystem functioning. In such a dynamic environment, lands selected to protect today's biodiversity may fail to do so in the future. One proposed approach to designing reserve networks that are robust to climate change involves protecting the diversity of abiotic conditions that in part determine species distributions and ecological processes. A set of abiotically diverse areas will likely support a diversity of ecological systems both today and into the future, although those two sets of systems might be dramatically different. Here, we demonstrate a conservation planning approach based on representing unique combinations of abiotic factors. We prioritize sites that represent the diversity of soils, topographies, and current climates of the Columbia Plateau. We then compare these sites to sites prioritized to protect current biodiversity. This comparison highlights places that are important for protecting both today's biodiversity and the diversity of abiotic factors that will likely determine biodiversity patterns in the future. It also highlights places where a reserve network designed solely to protect today's biodiversity would fail to capture the diversity of abiotic conditions and where such a network could be augmented to be more robust to climate-change impacts
A Tale of Four “Carp”: Invasion Potential and Ecological Niche Modeling
. We assessed the geographic potential of four Eurasian cyprinid fishes (common carp, tench, grass carp, black carp) as invaders in North America via ecological niche modeling (ENM). These “carp” represent four stages of invasion of the continent (a long-established invader with a wide distribution, a long-established invader with a limited distribution, a spreading invader whose distribution is expanding, and a newly introduced potential invader that is not yet established), and as such illustrate the progressive reduction of distributional disequilibrium over the history of species' invasions.We used ENM to estimate the potential distributional area for each species in North America using models based on native range distribution data. Environmental data layers for native and introduced ranges were imported from state, national, and international climate and environmental databases. Models were evaluated using independent validation data on native and invaded areas. We calculated omission error for the independent validation data for each species: all native range tests were highly successful (all omission values <7%); invaded-range predictions were predictive for common and grass carp (omission values 8.8 and 19.8%, respectively). Model omission was high for introduced tench populations (54.7%), but the model correctly identified some areas where the species has been successful; distributional predictions for black carp show that large portions of eastern North America are at risk.ENMs predicted potential ranges of carp species accurately even in regions where the species have not been present until recently. ENM can forecast species' potential geographic ranges with reasonable precision and within the short screening time required by proposed U.S. invasive species legislation
Coagulation changes in elective surgery and trauma.
Although antithrombin-3 (AT-3), a naturally-occurring inhibitor of thrombin, has been associated with a variety of thrombotic disorders, it has been studied in surgery and trauma. Three groups of patients were studied: Group I (20 patients) who underwent elective surgery; Group II (ten patients) who sustained moderate trauma: Group III (ten patients) who sustained severe trauma. Hypercoagulability panels were run preoperatively, intraoperatively, and postoperatively. Nine units of banked blood were also tested. The coagulation pattern changed during the stress, becoming hypercoagulable in proportion to the stress endured by the patient. In the severe trauma group, AT-3 fell significantly (p less than or equal to 0.002) in all patients, indicating extreme hypercoagulability. Three of these patients sustained thrombosis and loss of the involved extremity. The banked blood was found to be hypercoagulable. It appears that patients who sustain severe trauma, have multiple transfusions, and major operative procedures are at increased risk of developing postoperative thrombotic complications, including loss of limb
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Identification of a Threshold for Skeletal Muscle Injury
This study was designed to detect the first evidence of injury to muscle induced by passive stretching. Rabbit extensor digitorum longus and tibialis anterior skeletal muscles were subjected to passive stretching at set force levels of 20% or 30% of load to failure. Both tibialis anterior and extensor digitorum longus muscles that were stretched to 30% exhibited no difference in the three tensile parameters when compared with their con tralateral control specimens. Maximum contractile force was decreased after stretching. Tibialis anterior and ex tensor digitorum muscles that were stretched to 20% of control failure force showed no decrement in the tensile parameters or maximum contractile force. Histology of the extensor digitorum longus muscles stretched to 30% of failure force showed small focal areas of muscle fiber rupture and hemorrhage near the distal myoten dinous junction. Tibialis anterior and extensor digitorum longus muscle-tendon units stretched to 30% of failure force suffered functional injury as their contractile ability decreased after stretching. In contrast, muscle-tendon units stretched to 20% of failure force suffered no dec rement in contractile ability; therefore, a threshold for passive muscle stretch injury has been found. Further more, changes in contractile properties and histologic assessment appear to be more sensitive predictors of injury than measurement of structural failure properties
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Thermal effects on skeletal muscle tensile behavior
The effect of temperature on the mechanical failure properties of rabbit skeletal muscle (tibialis anterior and extensor digitorum longus) was examined. For all tests, one leg was maintained at 25°C and the contralateral leg at 40°C. Muscles were pulled to failure according to assignment into one of three groups: 1) passive failure at 10 cm/sec, 2) passive failure at 1 cm/sec, or 3) active (muscle is stimulated to contract as it is pulled) failure at 10 cm/sec. Load to failure was higher in the cold muscle for all groups tested. Total deformation was the same except in Group 1, when the warm muscle had a greater deformation. Energy absorbed before failure was greater in the cold muscle in Groups 2 and 3. Stiffness was higher in cold muscles for all muscles except the extensor digitorum longus in Group 1. In this study, temperature had a significant effect on the tensile properties; these thermal effects were de pendent on both loading rate and contractile state. Comparing loading rates, warm muscle tested at 10 cm/sec had higher failure loads than that tested at 1 cm/sec. Comparing stimulated versus unstimulated muscle (Group 1 versus Group 3), the stimulated tibialis anterior muscle absorbed more energy than unstimu lated ones. Stimulated extensor digitorum longus mus cles had higher failure loads, absorbed more energy, and were stiffer than nonstimulated muscles. This study offers experimental data to support the theory that warming muscles can aid in injury prevention and im provement in athletic performance
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