Timing of climate variability and grassland productivity

Future climates are forecast to include greater precipitation variability and more frequent heat waves, but the degree to which the timing of climate variability impacts ecosystems is uncertain. In a temperate, humid grassland, we examined the seasonal impacts of climate variability on 27 y of grass productivity. Drought and high-intensity precipitation reduced grass productivity only during a 110-d period, whereas high temperatures reduced productivity only during 25 d in July. The effects of drought and heat waves declined over the season and had no detectable impact on grass productivity in August. If these patterns are general across ecosystems, predictions of ecosystem response to climate change will have to account not only for the magnitude of climate variability but also for its timing.     

Outcomes in computer-assisted surgical simulation for orthognathic surgery

Orthognathic surgery is a powerful tool to address skeletal discrepancies of the jaws; however, the model surgery and splint fabrication necessary to successfully complete this surgery are laborious and time consuming. Previous studies have described the utility of computer-assisted surgical simulation (CASS) to eliminate the need for plaster cast model surgery. This article evaluates the implementation of a CASS system for treatment planning and splint fabrication in a series of 11 orthognathic surgery patients. All patients were treatment planned using a CASS system for computer-simulated osteotomies and splint fabrication. As a safety measure, traditional model surgery and splint fabrication were also performed on all cases. Each case was evaluated for accuracy of cephalometric analysis, splint accuracy, splint durability, and ease of treatment planning. All splints fit as well, or better, than those fabricated using traditional methods. In 2 cases, occlusal cants were detected by the CASS system that were undetected by traditional cephalometric analysis and physical examination. In 1 case, the skeletal midline identified on the computed tomographic scan was incongruent with the soft tissue clinical midline of the face, and this discrepancy was recognized and compensated for by correlation of the physical examination and preoperative clinical photos.In this series of 11 patients, the CASS system proved to be an effective mechanism to treatment plan cases and prepare surgical splints for patients undergoing orthognathic surgery.