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The development, validation, and use of new quantitative methodologies for testing the effectiveness of antimicrobial products are necessary to meet the regulatory challenges associated with an ever-changing marketplace, novel product claims, new infection control practices, and the emergence of new clinical pathogens. A series of four interlaboratory studies were conducted in a standardized manner on an interim quantitative method for testing liquid treatments against bacteria to assess its statistical performance. The Quantitative Method, a derivative of ASTM E2197, is designed to enumerate the number of viable microbes remaining on a test carrier following exposure to a liquid antimicrobial treatment; a log

Slow rates of coal-to-methane conversion limit biogenic methane production from coalbeds. This study demonstrates that rates of coal-to-methane conversion can be increased by the addition of small amounts of organic amendments. Algae, cyanobacteria, yeast cells, and granulated yeast extract were tested at two concentrations (0.1 and 0.5 g/L), and similar increases in total methane produced and methane production rates were observed for all amendments at a given concentration. In 0.1 g/L amended systems, the amount of carbon converted to methane minus the amount produced in coal only systems exceeded the amount of carbon added in the form of amendment, suggesting enhanced coal-to-methane conversion through amendment addition. The amount of methane produced in the 0.5 g/L amended systems did not exceed the amount of carbon added. While the archaeal communities did not vary significantly, the bacterial populations appeared to be strongly influenced by the presence of coal when 0.1 g/L of amendment was added; at an amendment concentration of 0.5 g/L the bacterial community composition appeared to be affected most strongly by the amendment type. Overall, the results suggest that small amounts of amendment are not only sufficient but possibly advantageous if faster in situ coal-to-methane production is to be promoted.

The mixed effects of temperature (20 °C, 25 °C and 30 °C), nitrate concentration (0.5 mM and 2.0 mM), pH buffer, and bicarbonate addition (trigger) on biomass growth and lipid accumulation were investigated in the environmental alga PW95 during batch experiments in standardized growth medium. PW95 was isolated from coal-bed methane production water and classified as a Chlamydomonas-like species by morphological characterization and phylogenetic analysis (18S, ITS, rbcL). A factorial experimental design tested the mixed effects on PW95 before and after nitrate depletion to determine a low cost, high efficiency combination of treatments for biomass growth and lipid accumulation. Results showed buffer addition affected growth for most of the treatments and bicarbonate trigger had no statistically significant effect on growth and lipid accumulation. PW95 displayed the highest growth rate and chlorophyll content at 30 °C and 2.0 mM nitrate and there was an inverse relation between biomass accumulation and lipid accumulation at the extremes of nitrate concentration and temperature. The combination of higher temperature (30 °C) and lower nitrate level (0.5 mM) without the use of a buffer or bicarbonate addition resulted in maximal daily biomass accumulation (5.30 × 106 cells/mL), high biofuel potential before and after nitrate depletion (27% and 20%), higher biofuel productivity (16 and 15 mg/L/d, respectively), and desirable fatty acid profiles (saturated and unsaturated C16 and C18 chains). Our results indicate an important interaction between low nitrate levels, temperature, and elevated pH for trade-offs between biomass and lipid production in PW95. This work serves as a model to approach and advance the study of physiological responses of novel microalgae to diverse culture conditions that mimic environmental changes for outdoor biofuel production. The most promising conditions for growth and biofuel production were identified for PW95 and this approach can be implemented for other microalgal production systems.

National Science Foundation under Grant No. 0628258; Defense University Research Instrumentation Program (DURIP, Contract Number: W911NF0510255); MSU Thermal Biology Institute from the NASA Exobiology Program (Project NAG5-8807)

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We describe an annealing procedure that computes the normalized N-cut of a weighted graph G. The first phase transition computes the solution of the approximate normalized 2-cut problem, while the low temperature solution computes the normalized N-cut. The intermediate solutions provide a sequence of refinements of the 2-cut that can be used to split the data to K clusters with 2 ≤ K ≤ N. This approach only requires specification of the upper limit on the number of expected clusters N, since by controlling the annealing parameter we can obtain any number of clusters K with 2 ≤ K ≤ N. We test the algorithm on an image segmentation problem and apply it to a problem of clustering high dimensional data from the sensory system of a cricket.

We apply the recently developed information distortion method (Comput. Neural Systems 12 (4) (2001) 441) to the analysis of coding by single neurons in the cricket cercal sensory system. This technique allows simultaneous identification of stimulus features and corresponding neural responses. The best approximation of a coding scheme that we obtained suggests that significant information is encoded in spike patterns. We compare this method to the linear stimulus reconstruction approach. Our coarsest nontrivial reproduction completely recovers the stimulus reconstruction results. Further refinements uncover additional structure, not present in the stimulus reconstruction results.