Spatial scales of interactions among bacteria and between bacteria and the leaf surface.

Microbial life on plant leaves is characterized by a multitude of interactions between leaf colonizers and their environment. While the existence of many of these interactions has been confirmed, their spatial scale or reach often remained unknown. In this study, we applied spatial point pattern analysis to 244 distribution patterns of Pantoea agglomerans and Pseudomonas syringae on bean leaves. The results showed that bacterial colonizers of leaves interact with their environment at different spatial scales. Interactions among bacteria were often confined to small spatial scales up to 5-20 μm, compared to interactions between bacteria and leaf surface structures such as trichomes which could be observed in excess of 100 μm. Spatial point-pattern analyses prove a comprehensive tool to determine the different spatial scales of bacterial interactions on plant leaves and will help microbiologists to better understand the interplay between these interactions

The Effect of Improved Brownstock Washing on Bleach Plant Effluent Quality

The objective of this thesis was to quantitatively determine the effects of reduced brownstock washer carryover on bleach plant effluent quality with respect to BOD and Color. More specifically; if efforts are made to reduce brownstock washer carryover by X pounds of BOD and Color, how many pounds of BOD and Color will be removed from the bleach plant sewer? Very little work has been done in this area. The laboratory procedure involved extensive washing of hardwood pulp and subsequent re-introduction of weak black liquor to simulate carryover. Black liquor was added as pounds Salt Cake loss per ton pulp. The pulp was then bleached by Chlorination - Extraction, varying the Chlorine charge to obtain a 2.5 Kappa Number. The resulting bleaching effluent (combined) was analyzed for BOD5, Color, and Total Organic Carbon (TOC)

Investigation of the soret effect in aqueous and non-aqueous mixtures by the thermal lens technique

In the present work we investigate the thermal diffusion behavior of three different binary mixtures with a thermal lens (TL) setup. In the setup used in this study we avoid the addition of a dye for systems, such as aqueous mixtures, with a weak absorption band at a wavelength of 980 nm. In some aqueous systems with a complex phase behavior the addition of dye significantly affects the apparent measured thermal diffusion properties. The studied systems are dimethylsulfoxide (DMSO) in water, the ionic liquid 1-ethyl-3-methylimidazolium ethylsulfate (EMIES) in butanol and a non-ionic surfactant hexaethylene glycol monododecyl ether (C(12)E(6)) in water. The Soret coefficients of the selected systems cover a range of two orders of magnitude. For DMSO in water with a very low Soret coefficient of the order of S(T) approximately 10(-3) K(-1) we find for a low DMSO content (c = 0.33) a reasonable agreement with previous measurements, while the weak thermal lens signal for the DMSO-rich mixture (c = 0.87) leads to 20% too large Soret coefficients with an uncertainty of more than 30%. Secondly we studied a liquid salt 1-ethyl-3-methylimidazolium ethylsulfate (EMIES) in butanol with a roughly ten times higher Soret coefficient of S(T) approximately 10(-2) K(-1). For this system we performed additional measurements with another experimental technique, the classical thermal diffusion forced Rayleigh scattering (TDFRS), which requires the addition of a small amount of dye to increase the absorption. In the entire investigated concentration range the results obtained with the TL and classical TDFRS technique agree within the error bars. As a third system we studied a non-ionic surfactant hexaethylene glycol monododecyl ether (C(12)E(6)) in water with a Soret coefficient of the order of S(T) approximately 10(-1) K(-1). For this system we find good agreement with previous measurements. We conclude that the TL technique is a reliable method for systems with a strong optical contrast and fairly large Soret coefficient of the order of S(T) approximately 10(-2) K(-1)

Experimental investigation of the Soret effect in acetone/water and dimethylsulfoxide/water mixtures

The thermal diffusion behavior of acetone/water and dimethylsulfoxide(DMSO)/water mixtures has been experimentally investigated by a transient holographic grating technique named thermal diffusion forced Rayleigh scattering (TDFRS). For both systems a sign change of the Soret coefficient S(T) with varying water content has been predicted by simulations [C. Nieto Draghi et al., J. Chem. Phys. 122, 114503 (2005)]. The sign change of S(T) is confirmed by the experiment. Except for equimolar concentrations of acetone/water the agreement between the experimental and simulation data is reasonable

Series approximations for Rayleigh distributions of arbitrary dimensions and covariance matrices

The multivariate Rayleigh distribution is of crucial importance to many applied problems of engineering, such as in the analysis of multi-antenna wireless systems. Due to the lack of a generalised closed form of the distribution, the dependence on effective approximation methods for evaluation has created numerous numerical approaches with considerable restrictions in both dimensionality, as well as the structure of covariance matrices. In this paper we extend a previously introduced method [1] without either of these limitations. We then compare the performance of the new algorithms to recent integration methods of fixed dimension, presented by Beaulie and Zhang [2] and highlight the advantages of the new method

New generalised approximation methods for the cumulative distribution function of arbitrary multivariate Rayleigh random variables

Based on our previous works, we revise a simple series expansion for multivariate probability density functions (PDF) of the Rayleigh distribution. From there we derive a similar expression for the cumulative density function (CDF) of multivariate Rayleigh random variables of arbitrary dimension and covariance matrix. The CDF is of particular interest as it can be used to compute outage probabilities of multi-channel wireless systems, for which we provide an example. We compare the performance of the newly proposed approximation to recently proposed methods based on numerical integration methods