Bioprocesses

The application of remote sensing techniques to the study of eutrophication in natural waters and the location and characterization of fronts is considered. The specific problem to be studied is examined along with the feasibility and capabability of remote sensing techniques for each application

Dust storms on Mars: Considerations and simulations

Aeolian processes are important in modifying the surface of Mars at present, and appear to have been significant in the geological past. Aeolian activity includes local and global dust storms, the formation of erosional features such as yardangs and depositional features such as sand dunes, and the erosion of rock and soil. As a means of understanding aeolian processes on Mars, an investigation is in progress that includes laboratory simulations, field studies of earth analogs, and interpretation of spacecraft data. This report describes the Martian Surface Wind Tunnel, an experimental facility established at NASA-Ames Research Center, and presents some results of the general investigation. Experiments dealing with wind speeds and other conditions required for the initiation of particle movement on Mars are described and considerations are given to the resulting effectiveness of aeolian erosion

Acute Sensitivity of Landslide Rates to Initial Soil Porosity

Some landslides move imperceptibly downslope, whereas others accelerate catastrophically. Experimental landslides triggered by rising pore water pressure moved at sharply contrasting rates due to small differences in initial porosity. Wet sandy soil with porosity of about 0.5 contracted during slope failure, partially liquefied, and accelerated within 1 second to speeds over 1 meter per second. The same soil with porosity of about 0.4 dilated during failure and slipped episodically at rates averaging 0.002 meter per second. Repeated slip episodes were induced by gradually rising pore water pressure and were arrested by pore dilation and attendant pore pressure decline

An Optical-based Aggregate Approach to Measuring Condensation Heat Transfer

Condensation heat transfer is significant in many applications such as such as desalination, energy conversion [1], atmospheric water harvesting [2, 3], electronics cooling, and other high heat flux applications [4]. However, condensate on the surface adds a thermal resistance that limits condensation rates. The rate of condensation heat transfer is inversely proportional to the diameter of the condensate drops [5]. In industrial condensing systems, the resistance is minimized by removing the condensate via gravity or a vapor shear, but the minimum size of droplet removal is typically on the order of the capillary length of the condensate, about 2.7 mm for water

Avalanche Dynamics in Wet Granular Materials

We have studied the dynamics of avalanching wet granular media in a rotating drum apparatus. Quantitative measurements of the flow velocity and the granular flux during avalanches allow us to characterize novel avalanche types unique to wet media. We also explore the details of viscoplastic flow (observed at the highest liquid contents) in which there are lasting contacts during flow, leading to coherence across the entire sample. This coherence leads to a velocity independent flow depth at high rotation rates and novel robust pattern formation in the granular surface.Comment: 5 pages, 3 figures in color, REVTeX4, for smaller pdfs see http://angel.elte.hu/~tegzes/condmat.htm

Results on Plasma Focusing of High Energy Density Electron and Positron Beams

We present results from the SLAC E-150 experiment on plasma focusing of high energy density electron and, for the first time, positron beams. We also discuss measurements on plasma lens-induced synchrotron radiation, longitudinal dynamics of plasma focusing, and laser- and beam-plasma interactions.Comment: LINAC 2000 paper No. THC13, Monterey, CA. Aug.21-25,2000, 3 pages, 2 figure

Does consumer protection enhance disclosure credibility in reward crowdfunding?

We study how the interplay of disclosure and regulation shapes capital allocation in reward crowdfunding. Using data from Kickstarter, the largest online reward crowdfunding platform, we show that, even in the absence of clear regulation and enforcement mechanisms, disclosure helps entrepreneurs access capital for their projects and bolsters engagement with potential project backers, consistent with the notion that disclosure mitigates moral hazard. We further document that, subsequent to a change in Kickstarter’s terms of use that increases the threat of consumer litigation, the association between project funding and disclosure becomes stronger. This evidence suggests that consumer protection regulation enhances the perceived credibility of disclosure. We find the effect of the change in terms of use to be more pronounced in states with stricter consumer protection regulations. Taken together, our findings yield important insights on the role of disclosure, as well as on the potential effects of increased regulation on crowdfunding platforms

Nutrition and its role in human evolution

Peer reviewedPostprin