997 resultados para Griswold, Rufus W. (Rufus Wilmot), 1815-1857.


Relevância:

50.00% 50.00%

Publicador:

Resumo:

Scan von Monochrom-Mikroform

Relevância:

50.00% 50.00%

Publicador:

Resumo:

Scan von Monochrom-Mikroform

Relevância:

50.00% 50.00%

Publicador:

Resumo:

Mode of access: Internet.

Relevância:

50.00% 50.00%

Publicador:

Resumo:

Originally prepared for the Evangelical Magazine and Gospel Advocate.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

Reductive acetogenesis is an alternative to methanogenesis for removing hydrogen produced during enteric fermentation. In Australia, kangaroos have evolved an enlarged forestomach analogous to the rumen of sheep and cattle. However, unlike sheep and cattle, kangaroos produce very little methane from enteric fermentation. From samples of gut contents from five eastern grey and three red kangaroos, we were not able to detect methanogens using a PCR protocol, but did detect the formyltetrahydrofolate synthetase (FTHFS) gene (likely to be used for reductive acetogenesis) in all animals. Isolations to recover acetogens resulted in two different classes of hydrogen consuming bacteria being isolated. The first class consisted of acetogens that possessed the FTHFS gene, which except for Clostridium glycolicum, were not closely related to any previously cultured bacteria. The second class were not acetogens but consisted of enterobacteria (Escherichia coli and Shigella) that did not possess FTHFS genes but did utilise hydrogen and produce acetate. Enumeration of the acetogens containing the FTHFS gene by real-time PCR indicated that bacteria of the taxa designated YE257 were common to all the kangaroos whereas YE266/YE273 were only detected in eastern grey kangaroos. When present, both species occurred at densities above *106 cell equivalents per mL. C. glycolicum was not detected in the kangaroos and, unlike YE257 and YE266/273, is unlikely to play a major role in reductive acetogenesis in the foregut of kangaroos.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

1. Many organisms inhabit strongly fluctuating environments but their demography and population dynamics are often analysed using deterministic models and elasticity analysis, where elasticity is defined as the proportional change in population growth rate caused by a proportional change in a vital rate. Deterministic analyses may not necessarily be informative because large variation in a vital rate with a small deterministic elasticity may affect the population growth rate more than a small change in a less variable vital rate having high deterministic elasticity. 2. We analyse a stochastic environment model of the red kangaroo (Macropus rufus), a species inhabiting an environment characterized by unpredictable and highly variable rainfall, and calculate the elasticity of the stochastic growth rate with respect to the mean and variability in vital rates. 3. Juvenile survival is the most variable vital rate but a proportional change in the mean adult survival rate has a much stronger effect on the stochastic growth rate. 4. Even if changes in average rainfall have a larger impact on population growth rate, increased variability in rainfall may still be important also in long-lived species. The elasticity with respect to the standard deviation of rainfall is comparable to the mean elasticities of all vital rates but the survival in age class 3 because increased variation in rainfall affects both the mean and variability of vital rates. 5. Red kangaroos are harvested and, under the current rainfall pattern, an annual harvest fraction of c. 20% would yield a stochastic growth rate about unity. However, if average rainfall drops by more than c. 10%, any level of harvesting may be unsustainable, emphasizing the need for integrating climate change predictions in population management and increase our understanding of how environmental stochasticity translates into population growth rate.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

Provision of artificial waterpoints in Australian rangelands has resulted in an increase in the range and density of kangaroos. At high densities, kangaroos can inhibit vegetation regeneration, particularly in some protected areas where harvesting is prohibited. Fencing off waterpoints has been proposed to limit these impacts. Our aim was to determine whether fencing off waterpoints during a drought (when kangaroos would be especially water-limited) would influence the density and distribution of red kangaroos (Macropus rufus). Two waterpoints were fenced within the first 6 months of the 27-month study and a further two waterpoints were kept unfenced as controls in Idalia National Park, western Queensland. We estimated kangaroo densities around waterpoints from walked line-transect counts, and their grazing distribution from dung-pellet counts. Fencing off waterpoints failed to influence either the density or distribution up to 4 km from the waterpoints. Our results indicate that food availability, rather than the location of waterpoints, determines kangaroo distribution. Few areas in the rangelands are beyond kangaroos' convenient reach from permanent waterpoints. Therefore, fencing off waterpoints without explicitly considering the spatial context in relation to other available water sources will fail to achieve vegetation regeneration.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

http://moa.umdl.umich.edu/cgi/sgml/moa-idx?notisid=ALQ8090

Relevância:

40.00% 40.00%

Publicador:

Resumo:

Voucher #7 from the Engineer Department of Port Dalhousie and Thorold Railway Extension to W.G. Thompson accompanied by an abstract of vouchers and summaries of account paid by W.G. Thompson for surveys, Jan. 31, 1857.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

Voucher #9 from the Engineer Department of Port Dalhousie and Thorold Railway Extension to W. G. Thompson accompanied by an abstract of vouchers for surveys, Feb. 28, 1857

Relevância:

40.00% 40.00%

Publicador:

Resumo:

Pay roll voucher #13 from the Engineer Department of Port Dalhousie and Thorold Railway Extension for the Northern Division for the month of April, 1857 approved by F. Shanly, chief engineer and W.G. Thompson, assistant engineer, April 27, 1857.

Relevância:

40.00% 40.00%

Publicador:

Resumo:

Pay roll voucher # 17 from the Engineer Department of Port Dalhousie and Thorold Railway Extension, for the Northern Division for the month of May, 1857, approved by F. Shanly, chief engineer and W.G. Thompson, assistant engineer, May 27, 1857.