Timothy is grown as a high value forage crop in California. Thrips (Anaphothrips obscurus Müller) have recently been implicated causing damage by increasing the quantity of brown leaves and lowering the value of this crop. Minimal studies have explored the relation of thrips levels to yield and damage in timothy and management options for this pest are extremely limited. We performed studies in...

The inverted U-shaped curves that presumably result from the observation that "as income goes up there is an increasing environmental degradation up to a point, after which environmental quality improves" [as quoted in Arrow et al. (1995) article] seem to be merely anecdotes that don't make history. What I mean is that although anecdotes can be true and elucidating, they are normally too limite...

Belonolaimus longicaudatus has long been recognized as a pathogen of potato (Solanum tuberosum). However, a damage function relating expected yield of potato to population densities of B. longicaudatus at planting has not been derived, and the economic threshold for nematicide application is unknown. The objectives of this study were to derive the damage function of B. longicaudatus on potato a...

We study an overlapping generations model of human capital accumulation with threshold effects using regional data for West Germany. Our basic goal is to shed light on what makes German regions grow. The paper finds that the relative income distribution appears to be stratifying into a trimodal distribution. Thus, application of the threshold model to a real world case, here West Germany, shows...

We introduce a game-theoretic model for network formation inspired by earlier stochastic models that mix localized and long-distance connectivity. In this model, players may purchase edges at distance d at a cost of d, and wish to minimize the sum of their edge purchases and their average distance to other players. In this model, we show there is a striking “small world” threshold phenomenon: i...

In this paper we study the issue of economic integration in Poland between 1924 and 1937 by means of a threshold cointegration analysis of the law of one price. We find that the interwar economy can be regarded as integrated but with obvious restrictions which refer to the existence of relevant transaction costs for arbitrage and differences in the level of prices between cities. Moreover, the ...

for determination of economic damage threshold of four wheat (triticum aestivum l.) cultivars in different densities of wild mustard (sinapis arvensis l.), experiments were conducted at agricultural research station gorgan during 2010-2012. the experimental design consisted of four randomized complete blocks in a factorial arrangement. the treatments comprised of factorial combination of wild m...

One of the fundamental concepts of integrated pest management is that each pest species has a definable relationship in terms of damage to the plant or animal host that it attacks. This relationship is often referred to as the damage curve (Fig. 1), which is often determined relative to yield loss. This damage curve can take several forms, but was summarized by Higley and Peterson as having a t...