Studies on the growth, viability, and lipids of Streptococcus bovis : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Animal Science

In their comprehensive review of rumen metabolism, Annison and Lewis (1959) emphasised the symbiotic relationship between the metabolic activities of the mixed population of anaerobic bacteria and ciliated protozoa, and the digestion of fodder consumed by the host. Prominent features of the microbial activity characterising the ruminant mode of digestion have been listed by Moir (1965) and may be summarised as follows: (1) Cellulose is hydrolysed to monosaccharides by microbial cellulases and carbohydrates fermented to volatile fatty aci s. While problems in the quantitative assessment of this volatile fatty acid production were reviewed by Warner (1964), it was also suggested that the amount produced in the rumen and absorbed directly into the blood stream, was sufficient to meet about 70 % of the host's energy requirements. (2) Microbial protein is synthesised from both plant protein and inorganic nitrogen with the energy released during carbohydrate fermentation. Although the extent of this conversion has also proved difficult to quantitate, Phillipson (1964) has stated that the microbial synthesis of essential amino acids, not always present in the diet, makes the ruminant almost independent of the quality of dietary protein. [From Introduction

External rebalancing is not just an exporters' story: real exchange rates, the non-tradable sector and the euro

Global and European trade balances have seen strong divergences combined with strong movements in the exchange rate. Trade balances and real effective exchange rates are related. Using different measures of the real effective exchange rate, we show that this long-run link hinges on the relative price of non-tradable to tradable goods and services in relation to their trading partners. An improvement in the trade balance is associated with a fall in the relative price of non-tradable goods and services. The elimination of nominal exchange rates with the euro does not change these relationships. Government consumption increases the relative price of nontradable goods. The results highlight the importance of internal price adjustments for external balances, a point frequently overlooked in policy debates.real exchange rate, non-tradable sector, euro

External rebalancing is not just an exporters' story: real exchange rates, the non-tradable sector and the euro

Global and European trade balances have seen strong divergences combined with strong movements in the exchange rate. Trade balances and real effective exchange rates are related. Using different measures of the real effective exchange rate, we show that this long-run link hinges on the relative price of non-tradable to tradable goods and services in relation to their trading partners. An improvement in the trade balance is associated with a fall in the relative price of non-tradable goods and services. The elimination of nominal exchange rates with the euro does not change these relationships. Government consumption increases the relative price of non-tradable goods. The results highlight the importance of internal price adjustments for external balances, a point frequently overlooked in policy debates.Real exchange rates, the non-tradable sector, the euro, Ruscher , Wolff

Prices and Price Dispersion on the Web: Evidence from the Online Book Industry

Using data collected between August 1999 and January 2000 covering 399 books, including New York Times bestsellers, computer bestsellers, and random books, we examine pricing by thirty-two online bookstores. One common prediction is that the reduction in search costs on the Internet relative to the physical channel would cause both price and price dispersion to fall. Over the sample period, we find no change in either price or price dispersion. Another prediction of the search literature is that the prices and price dispersion of advertised items or items that are purchased repeatedly will be lower than for unadvertised or infrequently purchased items. Prices across categories of books appear to conform to this prediction, with New York Times bestsellers having the lowest prices as a fraction of the publisher's suggested price and random books having the highest prices. Interestingly, price dispersion does not conform with this prediction, apparently for reasons related to stores' decisions to carry particular books. One reason why we may not observe convergence in prices is because stores have succeeded in differentiating themselves even though they are selling a commodity product. We observe differentiation (or attempted differentiation) by a significant number of firms.

Robust Control of Uncertain Markov Decision Processes with Temporal Logic Specifications

We present a method for designing robust controllers for dynamical systems with linear temporal logic specifications. We abstract the original system by a finite Markov Decision Process (MDP) that has transition probabilities in a specified uncertainty set. A robust control policy for the MDP is generated that maximizes the worst-case probability of satisfying the specification over all transition probabilities in the uncertainty set. To do this, we use a procedure from probabilistic model checking to combine the system model with an automaton representing the specification. This new MDP is then transformed into an equivalent form that satisfies assumptions for stochastic shortest path dynamic programming. A robust version of dynamic programming allows us to solve for a $\epsilon$-suboptimal robust control policy with time complexity $O(\log 1/\epsilon)$ times that for the non-robust case. We then implement this control policy on the original dynamical system

"Occupational and Industrial Mobility in the United States 1969–93"

Using the Panel Study of Income Dynamics, we investigate occupational and industrial mobility of individuals over the 1969–80 and 1981–93 periods in the United States. We find that workers changed both occupations and industries more frequently in the later period. For example, occupational mobility for men ranged from 15 to 20 percent per year during the first period and from 20 to 25 percent per year over the second. We also find that, for men, occupational and industrial changes are associated with lower earnings, though this effect has lessened somewhat over time, while for women the results are mixed. Our results also indicate that older and less educated workers are less likely to shift occupation or industry, as are better paid men but not better paid women.

Ice Sheets and the Anthropocene

Ice could play a role in identifying and defining the Anthropocene. The recurrence of northern hemisphere glaciation and the stability of the Greenland Ice Sheet are both potentially vulnerable to human impact on the environment. However, only a very long hiatus in either would be unusual in the context of the Quaternary Period, requiring the definition of a geological boundary. Human influence can clearly be discerned in several ice-core measurements. These include a sharp boundary in radioactivity due to atmospheric nuclear testing; increases, unprecedented at least in the Holocene, in Greenland concentrations of sulphate, nitrate and metals such as lead; the appearance in ice-core air bubbles of previously undetectable compounds such as SF6; and the rise, unprecedented in the last 800 ka, in concentrations of carbon dioxide and methane. Some combination of these changes could be used by future generations to clearly identify the onset of a new epoch defined at a particular calendar date. However, it is not yet clear what the character of the fully developed Anthropocene will be, and it might be wise to let future generations decide, with hindsight, when the Anthropocene started, acknowledging only that we are in the transition towards it

Hydrothermal circulation from very high to low temperatures in the lower oceanic crust : evidence from layered gabbros from the Oman ophiolite and from partial melting experiments on oceanic gabbros

[no abstract

Ancient air challenges prominent explanation for a shift in glacial cycles.

News and Views: An analysis of air up to 2 million years old, trapped in Antarctic ice, shows that a major shift in the periodicity of glacial cycles was probably not caused by a long-term decline in atmospheric levels of carbon dioxide.Royal Society Professorshi