Naturally sunlit, outdoor controlled-environment chambers provide an important research tool for studying the effects of environmental variables on crop physiological processes. Typically these types of chambers are semi-closed and are capable of continuously monitoring canopy scale gas exchanges. Accurately determining chamber CO2 leakage rate is essential for correcting measurements of photos...

Scaling is an integral component of ecology and earth science. To date, the ability to determine the importance of air – water gas exchange across large spatial scales is hampered partly by our ability to scale the gas transfer velocity and stream hydraulics. Here we report on a metadata analysis of 563 direct gas tracer release experiments that examines scaling laws for the gas transfer veloci...

Soil denitrification is considered the most unconstrained process in the global N cycle due to uncertain in situ N2 flux measurements, particularly in natural and semi-natural terrestrial ecosystems. N tracer approaches can provide in situ measurements of both N2 and N2O simultaneously, but their use has been limited to fertilized agroecosystems due to the need for large N additions in order to...

Gas exchange rates between natural waters and the atmosphere are an important component of our understanding of the dynamics of biologically active gases. For example, estimates of whole system metabolism must account for the transfer of gas (OJ between the atmosphere and water. Previous studies in estuaries have relied on dome measurements to estimate O2 exchange rates ( 1,2). In this study we...

At present, all physical models of diffuse Galactic gamma-ray emission assume that the distribution of cosmic-ray sources traces the observed populations of either OB stars, pulsars, or supernova remnants. However, since H2-rich regions host significant star formation and numerous supernova remnants, the morphology of observed H2 gas should also provide a physically motivated, high-resolution t...

A number of methods of measuring equilibria between solids and compressed gases have recently been described 1 and the results have been discussed in terms of molecular interactions in the gas phase.2 In the present paper, the experimental method used to investigate the system p-chloro.iodobenzene + ethylene will be described and the results will be given in detail. The measurements consisted i...

We present experimental visualizations of gas flow around solid blunt bodies by NMR imaging. NMR velocimetry is a model-free and tracer-free experimental means for quantitative and multi-dimensional flow visualization. Hyperpolarization of (129)Xe provided sufficient NMR signal to overcome the low density of the dilute gas phase, and its long coherence time allows for true velocity vector mappi...

I review the use of polarization data in the study of interstellar magnetic fields. On large scales in the interstellar medium, the polarization of background starlight is a good tracer of the projected plane-of-the-sky magnetic field structure in the neutral gas, and the field there appears to have roughly equal contributions from uniform and nonuniform components. In cases where a localized r...

An experimental study has been carried out of the two phase counter-current gas-liquid flow in a packed bed column operated in the proximity of the flooding point under periodic variations of inlet velocity of gas or liquid. Additional experiments have been focused on evaluating axial dispersion characteristics in the proximity of the flooding line in both liquid and gas phase using inert trace...