Search Results - (Author, Cooperation:R. I. Mackie)

2011-01-29

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Amino Acid Sequence ; Animals ; Bacteria/enzymology/*genetics/isolation & purification/metabolism ; Bacterial Proteins/chemistry/genetics/metabolism ; *Biomass ; Carbohydrate Metabolism ; Cattle/*microbiology ; Cellulase/genetics/metabolism ; Cellulases/chemistry/*genetics/metabolism ; Cellulose/*metabolism ; Cellulose 1,4-beta-Cellobiosidase/genetics/metabolism ; Genes, Bacterial ; Genome, Bacterial ; *Metagenome ; Metagenomics/methods ; Molecular Sequence Annotation ; Molecular Sequence Data ; Poaceae/microbiology ; Rumen/metabolism/*microbiology ; Sequence Analysis, DNA

1095-8649

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Endproducts of anaerobic fermentation, volatile fatty acids (VFAs), occur in the intestines of fish but no direct comparisons exist between VFA levels in fish with differing feeding ecologies during different seasons. We measured intestinal concentrations of six types of VFA in the upper and lower intestines of two freshwater omnivores (Cyprinus carpioi and Dorosoma cepedianum), and one piscivore (Micropterus salmoides) during the spring, summer and autumn. Acetate occurred in all species, and was highest in M. salmoides. In all species, concentrations were similar between upper and lower guts and higher during the summer. All three species contained anerobic bacteria and C. carpio and D. cepedianum contained cellulolytic types. Scanning electron microscopy revealed extensive colonization and suggested microbial breakdown of digesta in M. salmoides. In radio-tracer experiments, C. carpio dosed orally with [2–14C] acetate contained label in liver, muscle and blood tissues. Amounts of intestinal VFA did not appear to increase in species with refractile diets, and low VFA in D. cepedianum suggests fermentation plays a minimal role in the nutrition of this species. Low levels of intestinal VFA during cool seasons are consistent with the hypothesis that temperature limits fermentation in these Species.

Electronic Resource

1435-5663

Finite elements ; Object oriented methods

Springer Online Journal Archives 1860-2000

Computer Science

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Technology

Abstract Engineering software is becoming ever more complex. Finite element programs have sophisticated graphical input and output facilities, and are increasingly required to be linked to other software such as CAD or databases. The paper shows how an object oriented approach to finite element programming can be used to handle this complexity. This requires an approach that is very different from that adopted in more traditional programming. A foundation finite element class system is developed. This represents the essential data structure of the main finite element classes. It is then shown how this system can be used in a graphical model of two dimensional structures. The finite element system imposed no constraints on the development of the graphical model, yet could still be used easily. An important feature is that the nodes and elements are distributed around the graphical model, rather than being held centrally. For instance nodes may belong to points or lines of the graphical model. This means that the data structure used in the program more closely matches the way that the user of the program is likely to think.

Electronic Resource

1432-0614

Springer Online Journal Archives 1860-2000

Biology

Process Engineering, Biotechnology, Nutrition Technology

Abstract Methanogenesis was studied using stirred, bench-top fermentors of 3-1 working volume fed on a semi-continuous basis with waste obtained from cattle fed a high grain, finishing diet. Digestion was carried out at 40 and 60°C. CH4 production was 11.8, 18.3, 61.9 and 84.5% higher in the thermophilic than the mesophilic digestor at the 3, 6, 9 and 12 g volatile solids (VS) l−1 reactor volume loading rates, respectively. When compared on an energetic basis CH4 production was 7.4, 18.3, 72.9 and 107.3 kJ day higher in the thermophilic than the mesophilic digestor. CH4 production decreased more rapidly with each increase in VS loading rate and decrease in retention time (RT) in the mesophilic than the thermophilic digestor. When expressed as l g−1 VS fed or as kJ kJ−1 fed, the amount of CH4 was 49% less at the highest compared to the lowest loading rate in the mesophilic digestor. In the thermophilic digestor the decrease was only 16%. Propionate accumulated in the mesophilic digestor at the two highest loading rates, reaching concentrations of about 50 mM, but were only about 13 mM in the thermophilic digestor. Isobutyrate, isovalerate plus 2-methylbutyrate, and valerate also accumulated at the higher loading rates.

Electronic Resource

1432-0614

Springer Online Journal Archives 1860-2000

Biology

Process Engineering, Biotechnology, Nutrition Technology

Abstract  Methanogenesis was studied using stirred, bench-top fermentors of 3-l working volume fed on a semi-continuous basis with waste obtained from cattle fed a high grain, finishing diet. Digestion was carried out at 40 and 60°  C. CH4 production was 11.8, 18.3, 61.9 and 84.5% higher in the thermophilic than the mesophilic digestor at the 3, 6, 9 and 12 g volatile solids (VS) l–1 reactor volume loading rates, respectively. When compared on an energetic basis CH4 production was 7.4, 18.3, 72.9 and 107.3 kJ day higher in the thermophilic than the mesophilic digestor. CH4 production decreased more rapidly with each increase in VS loading rate and decrease in retention time (RT) in the mesophilic than the thermophilic digestor. When expressed as l g–1 VS fed or as kJ kJ–1 fed, the amount of CH4 was 49% less at the highest compared to the lowest loading rate in the mesophilic digestor. In the thermophilic digestor the decrease was only 16%. Propionate accumulated in the mesophilic digestor at the two highest loading rates, reaching concentrations of about 50 mm, but were only about 13 mm in the thermophilic digestor. Isobutyrate, isovalerate plus 2-methylbutyrate, and valerate also accumulated at the higher loading rates.

Electronic Resource

0001-1541

Chemistry ; Chemical Engineering

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Process Engineering, Biotechnology, Nutrition Technology

Previous attempts to model the effect of deposition on removal efficiency in deep-bed filtration have relied heavily on the determination of empirical parameters even for monosized suspensions. A newly developed mathematical model not only significantly reduces this reliance, but takes full account of the polydispersity of suspensions. The results of eight runs on an experimental filter are compraed with the predictions of the mathematical model. Qualitative agreement is good; quantitative agreement is fair.

12 Ill.

Electronic Resource

0001-1541

Chemistry ; Chemical Engineering

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Process Engineering, Biotechnology, Nutrition Technology

Electronic Resource

0029-5981

Engineering ; Engineering General

Wiley InterScience Backfile Collection 1832-2000

Mathematics

Technology

The finite element method is by its nature very modular. Object oriented programming enables full advantage to be taken of this modularity. This makes for safer and easier programming, and extending or modifying object oriented programs is very straightforward. The paper describes an object oriented implementation of the finite element method, and illustrates the advantages of the approach.

2 Ill.

Electronic Resource

1069-8299

Engineering ; Engineering General

Wiley InterScience Backfile Collection 1832-2000

Mathematics

Technology

A technique is presented whereby numerical calculations of vibration modes can be improved. The paper looks at the classical two-dimensional wave equation using finite difference approximations. Analysis of the numerical dispersion of the approximations is used to develop a correction method. In general the numerical dispersion is dependent upon both the frequency and the direction of a wave, but if a 9-point formula is used the directional dependence is much reduced. This enables correction factors to be obtained using only the frequency of a vibration mode. The method was tested on the vibration of a square membrane and of an L-shaped region; in both cases a marked improvement in accuracy was obtained, at very little computational cost.

5 Ill.

Electronic Resource

0029-5981

Engineering ; Engineering General

Wiley InterScience Backfile Collection 1832-2000

Mathematics

Technology

A technique is presented whereby the standard finite element approximations used in vibration analysis are modified in order to allow them to accurately predict the frequencies of the higher modes. This is done by using the results of dispersion analysis of the numerical approximations. The method is applied to the longitudinal vibration of a bar, and is shown to give good results for a uniform bar, a bar with continuously varying properties, and a bar with a step change in properties. Dispersion correction gives improved accuracy for the flexural vibration of a beam. The results of the method are also applied to the mode superposition method of dynamic analysis, and again a marked improvement in performance is obtained.

5 Ill.

Electronic Resource