The Alaska Arctic Vegetation Archive (AVA-AK)

The Alaska Arctic Vegetation Archive (AVA-AK, GIVD-ID: NA-US-014) is a free, publically available database archive of vegetation-plot data from the Arctic tundra region of northern Alaska. The archive currently contains 24 datasets with 3,026 non-overlapping plots. Of these, 74% have geolocation data with 25-m or better precision. Species cover data and header data are stored in a Turboveg database. A standardized Pan Arctic Species List provides a consistent nomenclature for vascular plants, bryophytes, and lichens in the archive. A web-based online Alaska Arctic Geoecological Atlas (AGA-AK) allows viewing and downloading the species data in a variety of formats, and provides access to a wide variety of ancillary data. We conducted a preliminary cluster analysis of the first 16 datasets (1,613 plots) to examine how the spectrum of derived clusters is related to the suite of datasets, habitat types, and environmental gradients. We present the contents of the archive, assess its strengths and weaknesses, and provide three supplementary files that include the data dictionary, a list of habitat types, an overview of the datasets, and details of the cluster analysis

Implementing the LPM effect in a parton cascade model

Parton Cascade Models (PCM), which describe the full time-evolution of a system of quarks and gluons using pQCD interactions are ideally suited for the description of jet production, including the emission, evolution and energy-loss of the full parton shower in a hot and dense QCD medium. The Landau-Pomeranchuk-Migdal (LPM) effect, the quantum interference of parton wave functions due to repeated scatterings against the background medium, is likely the dominant in-medium effect affecting jet suppression. We have implemented a probabilistic implementation of the LPM effect within the PCM which can be validated against previously derived analytical calculations by Baier et al (BDMPS-Z). Presented at the 6th International Conference on Physics and Astrophysics of Quark Gluon Plasma (ICPAQGP 2010).Comment: 4 pages, 1 figure. A proceeding of ICPAGQP 201

Multidimensionally resolved pore size distributions

A novel method of determining median pore size and pore size distributions as a function of spatial position inside a porous sample is described. Pore sizes have been measured with 1-, 2- and 3-dimensional spatial resolution, using NMR cryoporometry in conjunction with magnetic resonance imaging techniques. The method is suitable for pore diameters in the range of 30 Angstrom to over 2000 Angstrom pore diameter, and is based on the technique of freezing a liquid in the pores and measuring the melting temperature by nuclear magnetic resonance. Since the melting point is depressed for crystals of small size, the melting point depression gives a measurement of pore size

Equilibrium Constants for Hydrocarbons in Absorption Oil

The economical recovery of the valuable constituents from the effluent ofgas-condensate wells has developed into a problem of balancing the cost ofrecovery against the cost of compressing the residual gas back into theformation. A possible method of extracting the gasoline and distillate from thenatural gas is by oil absorption at high pressures. In order to design andevaluate an absorption plant, fundamental data on the composition of thecoexisting hydrocarbon vapor and liquid phases at various temperatures andpressures are essential. A review of the literature indicated that the necessary data for the design ofsuch plants are lacking. The nearest approach to desired published data is thatof Katz and Hackmuth, who experimentally determined the composition of thecoexisting vapor and liquid phases in a natural gas-crude oil system atpressures up to 3000 lb. per sq. in. and at temperatures from 40? to200?F. This paper presents the results of the experimental determination of theequilibrium distribution of the hydrocarbons methane through hexane betweennatural gas and a typical absorber oil. The ranges of temperature and pressurechosen were from 33? to 180?F. and from 100 to 5000 lb. per sq. inch. Materials The absorber oil was a typical naturally occurring, straw-colored distillatethat had previously been steam-distilled to an initial boiling point of 300?F.The physical and chemical properties, including the results of an Englerdistillation, are presented in Table I. A large volume of this oil was obtainedand it was used throughout the complete set of experiments. The n-hexane was obtained from the Ohio Chemical and Manufacturing Co., Cleveland, Ohio. This liquid had a boiling range of from 149? to I52.6?F., witha density of 0.667 at 60?F. and a molecular weight of 85 by benzenefreezing-point depression. The propane, isobutane, n-butane, isopentane andn-pentane were obtained from the Philgas Department of the Phillips PetroleumCo. Certified analyses of these compounds showed their purity to be in excessof 99.5 per cent and they were not further purified. T.P. 1252 </jats:sec