The exchange of carbon on earth is one of the fundamental processes that sustains life and regulates climate. Since the onset of the Industrial Revolution, the burning of fossil fuels and anthropogenic land conversion have altered the carbon cycle, increasing carbon dioxide in the atmosphere to levels that are unprecedented...
The last glacial period exhibited abrupt Dansgaard–Oeschger climatic oscillations, evidence of which is preserved in a variety of Northern Hemisphere palaeoclimate archives¹. Ice cores show that Antarctica cooled during the warm phases of the Greenland Dansgaard–Oeschger cycle and vice versa[superscript 2,3], suggesting an interhemispheric redistribution of heat through a mechanism...
An important constraint on mechanisms of past
carbon cycle variability is provided by the stable isotopic
composition of carbon in atmospheric carbon dioxide (δ¹³C-CO₂) trapped in polar ice cores, but obtaining very precise
measurements has proven to be a significant analytical challenge.
Here we describe a new technique to determine...
Dyphylline has been shown to be rapidly and completely
absorbed from oral tablets in an absolute bioavailability
study. In a pilot study two healthy male subjects received
1000 mg of dyphylline via intravenous infuson at a rate of
50 mg/min (1.0 ml/min) for 20 minutes. Plasma samples were
collected for...
The purpose of this study was to develop, implement, and test methods for
quantifying the relative proportion of hardwood and conifer cover from Thematic Mapper
(TM) imagery. The research was focused on closed canopy forests in the Oregon Coast
Range, where hardwood, conifer, and mixed stand conditions are prevalent. Based...
Aquatic insect population counts can be a good indicator of the health, or water quality, of rivers and streams. Stoneflies (Plecoptera) are particularly susceptible to pollution in streams. However, today’s current method for obtaining these population counts requires biologists to examine individual specimens under a microscope for identification to the...
Observations of the scale-dependent turbulent fluxes, variances, and the bulk transfer parameterization for sensible heat above, within, and beneath a tall closed Douglas-fir canopy in very weak winds are examined. The daytime sub-canopy vertical velocity spectra exhibit a double-peak structure with peaks at timescales of 0.8 s and 51.2 s....
This paper presents the design and evaluates the performance of a double-walled electrically aspirated radiation shield for thermometers measuring air temperature and its gradients in the atmospheric surface layer. Tests were performed to quantify its solar radiation error and wake production, and to characterize the observer effect of the forced...
Microprogramming has evolved since its introduction in 1951 by Maurice Wilkes. The most significant change that has taken place is the recent growth of interest in user microprogramming. However, user microprogramming is a difficult task because of various complex and intricate features of the host processors. A microprogrammer must be...