Biogeochemical silica mass balances in Lake Michigan and Lake Superior

Silica budgets for Lake Michigan and Lake Superior differ in several respects. Mass balance calculations for both lakes agree with previous studies in that permanent burial of biogenic silica in sediments may be only about 5% of the biogenic silica produced by diatoms. Because dissolution rates are large, good estimates of permanent burial of diatoms can not be obtained indirectly from the internal cycle of silica (silica uptake by diatoms and subsequent dissolution) but must be obtained from the sediment stratigraphy. The annual net production of biogenic silica in Lake Michigan requires 71% of the winter maximum silica reservoir which must be maintained primarily by internal cycling in this large lake whereas the comparable silica demand in Lake Superior is only 8.3%. The greater silica demand in Lake Michigan is the result of phosphorus enrichment which has increased diatom production. It is hypothesized that steady-state silica dynamics in Lake Michigan were disrupted by increased diatom production between 1955 and 1970 and that a new steady state based on silica-limited diatom production developed after 1970. Mass balance calculations for Lake Michigan show in contrast with previous work that the hypothesized water column silica depletion of 3.0 g · m −3 could have occurred even though 90% or more of the biogenic silica production is recycled.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42471/1/10533_2004_Article_BF02187199.pd

The distribution of stock returns

A detailed examination is made of the distribution of stock returns following reports that the distribution is best described by the symmetric stable class of distributions. The distributions are shown to be “fat-tailed” relative to the normal distribution but a number of properties inconsistent with the stable hypothesis are noted. In particular, the standard deviation appears to be a well behaved measure of scale

The Prices Justification Tribunal: Retrospect and Prospect

Because empirical measurement of the PJT's effectiveness is very difficult, the PJT is evaluated analytically. It is concluded that the only sensible role for the PJT is to reduce inflationary expectations when the underlying causes of inflation are no longer present. There is little or no evidence that the PJT has been successful in this regard. An examination of the PJT's decisions indicate many inconsistencies with those of other government bodies and with optimal resource allocation. The PJT owes its continued existence almost completely to political factors

Risk, Uncertainty and Farm Management Decisions

The objective of this paper is to give a brief exposition of the decision criteria commonly propounded for decisions under risk and uncertainty. The review of these criteria in the context of farm management decisions reiterates the inappropriateness of all except the expected utility hypothesis, and it is concluded that utility analysis has considerable potential as an operational tool in farm management

Asset pricing in the Australian industrial equity market

The two-moment, mean-variance model of asset pricing is tested against data from the Melbourne stock exchange. The model appears to describe the data quite well, though there are problems in experimental design which are yet to be cleared up. Neither variance nor skewness appears to explain additional price behaviour to that explained by covariance, as is predicted by the two-moment model

Risk, Uncertainty and Farm Management Decisions

The objective of this paper is to give a brief exposition of the decision criteria commonly propounded for decisions under risk and uncertainty. The review of these criteria in the context of farm management decisions reiterates the inappropriateness of all except the expected utility hypothesis, and it is concluded that utility analysis has considerable potential as an operational tool in farm management.Farm Management, Risk and Uncertainty,

RISK, UTILITY AND THE PALATABILTY OF EXTENSION ADVICE TO FARMER GROUPS

Using the results of an empirical study of farmers' utility functions, evidence is presented that risk plays a measurable role in farmer decision making. The extension implications of such risk influences are discussed with particular emphasis on the possible efficacy of using group utility functions as a basis for group recommendations