The movement of sediment in a channel in relation to magnitude and frequency concepts- a New Zealand example

In areas where surface wash contributes most of the debris to a channel network, the effect of events of moderate magnitude and frequency appear to be more important than catastrophic events for land form development. In previous studies this idea has been emphasised, largely as a result of the fact that the contribution of bedload to sediment yield has rarely been considered. Examination of these ideas under certain New Zealand conditions would seem to present a somewhat different picture. Where rapid mass movement is the main contributor of sediment to the channel, both the development of hill-slope form and the movement of sediment in channels must be related to the frequency of occurrence of mass movements. The evidence seems to suggest that most major mass movements are triggered during high-intensity, low-frequency storms. The Orere River catchment in the Hunua greywacke block of South Auckland, New Zealand, is examined to test these ideas. Although historical data are limited, the character of the sediments in the lower catchment would suggest a succession of major periods of deposition. High-intensity storms of 1966 and 1967 resulted in the deposition of large amounts of material in the channels throughout the catchment, with a gradual removal of material mainly from the upper catchment since that time. From the limited evidence that is available, a simple model of sediment movement through the catchment is presented

Impact of broom, Cytisus scoparius (Fabaceae), in naturally treeless sub-alpine frost-hollow vegetation communities at the Barrington Tops, south-eastern Australia

The exotic shrub Cytisus scoparius (L.) Link (family Fabaceae), known as broom, is having a major impact on native vegetation in naturally treeless sub-alpine frost-hollow areas (c. 32o 01’ 37” S, 151o 26’ 12” E’, 1440 m elevation) at the Barrington Tops, New South Wales, in south-eastern Australia. This vegetation is of limited extent and has significant biogeographical and ecological importance. Nine paired 10 m line transects were compared, with one of the pair in areas of almost 100% Cytisus scoparius and the other in adjacent areas without Cytisus scoparius. Results were compared with species recorded from this area in the 1930s. There are obvious differences in native vegetation in areas with and without Cytisus scoparius. On average there were 5.1 (range 2–10) species per 10 m in areas of almost 100% Cytisus scoparius cover and 17.0 (12–25) species per 10 m in areas adjacent to infested areas but without Cytisus scoparius. Other than Cytisus scoparius, the area surveyed had little in the way of exotic species and these were only present at low densities. Native species present in 2008 are similar to those recorded in the 1930s; there were no records of Cytisus scoparius in the area in the 1930s. The study suggests that control of Cytisus scoparius in naturally treeless areas at the Barrington Tops should be a priority to prevent a decline in the distribution and abundance of many plant species, many of which only occur in treeless areas of the Barrington Tops

The Value of the Trout Fishery at Rhodes, North Eastern Cape, South Africa, A Travel Cost Analysis Using Count Data Models

The National Environmental Management: Biodiversity Act, no.10 of 2004) makes provision for the presence of alien trout in South African waters by means of a zoning system, partly in recognition of the significant income generating potential of trout fishing in South Africa. This paper reports the first formal recreational valuation of a trout fishery in South Africa, the one in and around Rhodes village, North Eastern Cape. The valuation is carried out by applying the individual travel cost method using several count data models. The zero truncated negative binomial model yielded the most appealing results. It accounts for the non-negative integer nature of the trip data, for truncation and over-dispersion. The paper finds that in 2007 consumer surplus per day visit to the Rhodes trout fishery was R2 668, consumer surplus per trip visit was R13 072, and the total consumer surplus generated was R18 026 288.

A stochastic maximum principle for a stochastic differential game of a mean-field type

We construct a stochastic maximum principle (SMP) which provides necessary conditions for the existence of Nash equilibria in a certain form of N-agent stochastic differential game (SDG) of a mean-field type. The information structure considered for the SDG is of a possible asymmetric and partial type. To prove our SMP we use a spike-variation approach with adjoint representation techniques, analogous to that of S. Peng in the optimal stochastic control context. In our proof we apply adjoint representation procedures at three points. The first-order adjoint processes are defined as solutions to certain mean-field backward stochastic differential equations, and second-order adjoint processes of a first type are defined as solutions to certain backward stochastic differential equations. Second-order adjoint processes of a second type are defined as solutions of backward stochastic equations of a type that we introduce in this paper, and which we term conditional mean-field backward stochastic differential equations. From the resulting representations, we show that the terms relating to these second-order adjoint processes of the second type are of an order such that they do not appear in our final SMP equations

Effects of Insider Trading on the Bong Market

The bond market is affected by many of the same things the stock market is. When insiders trade stock of their own firm, Investors take this as a signal. Insiders are assumed to have an advantage by their position in the firm to know how well the price of the stock is going to do. Insiders are also assumed to take advantage of this information in trading for their account around the laws dictated by the Securities and Exchange Act of 1934. When significant news is going to be announced about a company, the stock price may begin changing prior to the announcement. This study examines the bond market to see if insiders make abnormal returns. It was found that there is some significant insider trading around the announcement date of insiders trading stock at the eight percent level for buyers and at the five percent level for sellers.B.S. (Bachelor of Science