ABSTRACT
Prediction of the impact of climate change requires the response of carbon (C) flow in plant-soil systems to increased CO(2) to be understood. A mechanism by which grassland C sequestration might be altered was investigated by pulse-labelling Lolium perenne swards, which had been subject to CO(2) enrichment and two levels of nitrogen (N) fertilization for 10 yr, with (14)CO(2). Over a 6-d period 40-80% of the (14)C pulse was exported from mature leaves, 1-2% remained in roots, 2-7% was lost as below-ground respiration, 0.1% was recovered in soil solution, and 0.2-1.5% in soil. Swards under elevated CO(2) with the lower N supply fixed more (14)C than swards grown in ambient CO(2), exported more fixed (14)C below ground and respired less than their high-N counterparts. Sward cutting reduced root (14)C, but plants in elevated CO(2) still retained 80% more (14)C below ground than those in ambient CO(2). The potential for below-ground C sequestration in grasslands is enhanced under elevated CO(2), but any increase is likely to be small and dependent upon grassland management.
Subject(s)
Carbon Dioxide/analysis , Carbon/metabolism , Ecosystem , Lolium/metabolism , Photosynthesis , Zea mays/metabolism , Carbon/analysis , Carbon Dioxide/metabolism , Lolium/growth & development , Nitrogen/metabolism , Oxygen Consumption , Soil , Zea mays/growth & developmentABSTRACT
Gamma-ray bursts (GRBs) and their afterglows are the most brilliant transient events in the Universe. Both the bursts themselves and their afterglows have been predicted to be visible out to redshifts of z approximately 20, and therefore to be powerful probes of the early Universe. The burst GRB 000131, at z = 4.50, was hitherto the most distant such event identified. Here we report the discovery of the bright near-infrared afterglow of GRB 050904 (ref. 4). From our measurements of the near-infrared afterglow, and our failure to detect the optical afterglow, we determine the photometric redshift of the burst to be z = 6.39 - 0.12 + 0.11 (refs 5-7). Subsequently, it was measured spectroscopically to be z = 6.29 +/- 0.01, in agreement with our photometric estimate. These results demonstrate that GRBs can be used to trace the star formation, metallicity, and reionization histories of the early Universe.
ABSTRACT
OBJECTIVE: Obtunded patients (Glasgow Coma Scale score of < 13) with normal cervical roentgenograms remain in collars until they can be clinically evaluated. Cervical collars provide incomplete immobilization and have complications. Our hypothesis was that cervical spines could be evaluated in obtunded patients with normal cervical roentgenograms using dynamic fluoroscopy. DESIGN: This study was a prospective clinical evaluation. METHODS: Obtunded trauma patients with normal cervical roentgenograms underwent fluoroscopic examination of the cervical spine through a full range of motion. RESULTS: Fluoroscopic evaluations were done in 116 patients. There were 113 true negative examinations. Two patients had facet fractures not diagnosed on cervical roentgenograms, and no instability on fluoroscopy. One patient had a positive exam, with 2 mm of subluxation. There were no neurologic complications. Decubiti were present in 44% and were more frequent when the collar was on > 5 days (p = 0.029). CONCLUSIONS: Dynamic fluoroscopy can safely and effectively clear the cervical spine in obtunded patients. Earlier removal of the collar decreases decubiti.
Subject(s)
Cervical Vertebrae/diagnostic imaging , Cervical Vertebrae/injuries , Coma , Immobilization , Adult , Coma/etiology , Female , Fluoroscopy , Humans , Immobilization/adverse effects , Male , Middle Aged , Prospective StudiesABSTRACT
Peroneal nerve injury is a common peripheral neuropathy from a variety of conditions and injuries. We encountered a case of peroneal nerve palsy in a professional bungee cord jumper. Review of the literature showed no previous report of this particular injury in bungee cord jumping.
