23,359 research outputs found
Safeguarding the banking system in an environment of financial cycles: an overview
Banks and banking ; Risk ; Banking law ; Bank supervision
Sustainability, Externalities and Economics: The Case of Temperate Perennial Grazing Systems in NSW
The replacement of perennial grass species by undesirable annual grass weeds not only results in lower productivity but is also contributes to a range of external costs. In particular, shallow rooted annuals result in greater deep drainage and therefore a greater potential for salinity, and greater volumes of runoff of poor quality water to streams. In this paper an economic framework for examining the sustainability issues of a perennial grazing system on the NSW Central Tablelands is presented. This involves a combination of simulation and dynamic programming models, with the state of the system represented by variables for the perennial grass composition and soil fertility. The paper examines a range of management strategies that increase the perennial grass composition in terms of net income from grazing, and the impact upon the externalities.perennial pasture, sustainability, externalities, bioeconomic modelling, dynamic programming, Research and Development/Tech Change/Emerging Technologies, 160,
A Dynamic Optimisation Model of Weed Control
It is argued in this paper that static approaches to weed management, where the benefits and costs are only considered within a single season, are inappropriate for assessing the economic benefits of weed control technologies. There are carryover effects from weed management as weeds that escape control in one season may reproduce and replenish weed populations in following seasons. Consequently, it is appropriate to view weed control in the context of a resource management problem where the goal is to determine the optimal inter-temporal level of weed control that maximises economic benefits over some pre-determined period of time. A dynamic optimisation model for weed control is presented. Using the tools of comparative static analysis and Pontryagin's maximum principle, the conditions for optimal input use (ie weed control) are compared for static and dynamic situations. It is shown that a higher level of input use for a given weed population is optimal using a dynamic framework than would be derived under a static framework. The analysis is further extended by the incorporation of uncertainty and shows that the optimal level of weed control is also affected by uncertainty in herbicide efficacy and the survival of weed seeds produced. A case study of the optimal long-term management under deterministic and stochastic conditions of an annual cropping weed, Avena fatua, is presented.weed control, resource economics, optimal control, dynamic programming, wild oats, Farm Management,
Rational Arithmetic Mathematica Functions to Evaluate the One-sided One-sample K-S Cumulative Sample Distribution
One of the most widely used goodness-of-fit tests is the Kolmogorov-Smirnov (KS) family of tests which have been implemented by many computer statistical software packages. To calculate a p value (evaluate the cumulative sampling distribution), these packages use various methods including recursion formulae, limiting distributions, and approximations of unknown accuracy developed over thirty years ago. Based on an extensive literature search for the one-sided one-sample K-S test, this paper identifies two direct formulae and five recursion formulae that can be used to calculate a p value and then develops two additional direct formulae and four iterative versions of the direct formulae for a total of thirteen formulae. To ensure accurate calculation by avoiding catastrophic cancelation and eliminating rounding error, each formula is implemented in rational arithmetic. Linear search is used to calculate the inverse of the cumulative sampling distribution (find the confidence interval bandwidth). Extensive tables of bandwidths are presented for sample sizes up to 2, 000. The results confirm the hypothesis that as the number of digits in the numerator and denominator integers of the rational number test statistic increases, the computation time also increases. In comparing the computational times of the thirteen formulae, the direct formulae are slightly faster than their iterative versions and much faster than all the recursion formulae. Computational times for the fastest formula are given for sample sizes up to fifty thousand.
Why supersymmetry should be restored at the TeV scale
It is explained why the curvature associated to the vacuum energy density
arising from SUSY breaking cannot be completely transferred to the extra
spatial dimensions of a bulk space-time manifold, and it is shown -- without
using hierarchy arguments but only the results of current large-scale
observations -- why the Tev scale should correspond to the maximal allowed
SUSY-breaking scale.Comment: 6 pages. Essay written for the 2008 Awards for Essays on Gravitation
(Gravity Research Foundation, USA), and awarded with "Honorable Mention
A bioeconomic model for determining the optimal response to a new weed incursion in Australian cropping systems
Invasions by non-indigenous plant species pose serious economic threats to Australian agricultural industries. When an invasion is discovered a decision has to be made as to whether to attempt to eradicate it, contain it or do nothing. These decisions should be based on long term benefits and costs. This paper describes a bioeconomic simulation framework with a mathematical model representing weed spread linked to a dynamic programming model to provide a means of determining the economically optimal weed management strategies over time. The modelling framework is used to evaluate case study invasive weed control problems in the Australian grains industry.weeds, incursion, bioeconomic model, Crop Production/Industries, Research Methods/ Statistical Methods,
Arbitrary Precision Mathematica Functions to Evaluate the One-Sided One Sample K-S Cumulative Sampling Distribution
Efficient rational arithmetic methods that can exactly evaluate the cumulative sampling distribution of the one-sided one sample Kolmogorov-Smirnov (K-S) test have been developed by Brown and Harvey (2007) for sample sizes n up to fifty thousand. This paper implements in arbitrary precision the same 13 formulae to evaluate the one-sided one sample K-S cumulative sampling distribution. Computational experience identifies the fastest implementation which is then used to calculate confidence interval bandwidths and p values for sample sizes up to ten million.
Throwing Good Money after Bad? Board Connections and Conflicts in Bank Lending
This paper investigates the frequency of connections between banks and non-financial firms through board linkages and whether those connections affect lending and borrowing behavior. Although a board linkages may reduce the costs of information flows between the lender and borrower, a board linkage may generate pressure for special treatment of a borrower not normally justifiable on economic grounds. To address this issue, we first document that banks are heavily involved in the corporate governance network through frequent board linkages. Banks tend to have larger boards with a higher proportion of outside directors than non-financial firms, and bank officer-directors tend to have more external board directorships than executives of non-financial firms. We then show that low-information cost firms – large firms with a high proportion of tangible assets and relatively stable stock returns -- are most likely to have board connections to banks. These same low-information cost firms are also more likely to borrow from their connected bank, and when they do so the terms of the loan appear similar to loans to unconnected firms. In contrast to studies of Mexico, Russia and Asia where connections have been misused, our results suggest that avoidance of potential conflicts of interest explains both the allocation and behavior of bankers in the U.S. corporate governance system.
The release of a captive-raised female African Elephant <em>(Loxodonta africana</em>) in the Okavango Delta, Botswana
Wild female elephants live in close-knit matrilineal groups and housing captive elephants in artificial social groupings can cause significant welfare issues for individuals not accepted by other group members. We document the release of a captive-raised female elephant used in the safari industry because of welfare and management problems. She was fitted with a satellite collar, and spatial and behavioural data were collected over a 17-month period to quantify her interactions with the wild population. She was then monitored infrequently for a further five-and-a-half years. We observed few signs of aggression towards her from the wild elephants with which she socialized. She used an area of comparable size to wild female elephants, and this continued to increase as she explored new areas. Although she did not fully integrate into a wild herd, she had three calves of her own, and formed a social unit with another female and her calf that were later released from the same captive herd. We recommend that release to the wild be considered as a management option for other captive female elephants
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