In 1992 neurophysiologists [20] found a new type of cells in areas V1 and V2 of the monkey primary visual cortex, which they called grating cells. These cells respond vigorously to a grating pattern of appropriate orientation and periodicity. Three years later a computational model inspired by these findings was published [9]. The study of this paper is to create a grating cell operator that ha...

The quality of Dutch nature reserves is threatened by high nitrogen input, a problem which to a large extent is caused by agricultural activities. The Dutch government intends to solve this by designating some areas where the emission level is allowed to increase and other areas where the emission level will have to decrease. Theoretically, this problem can be seen as a reallocation of emission...

The ixodid tick burdens of eland (Taurotragus oryx), greater kudu (Tragelaphus strepsiceros), nyala (Tragelaphus angasi), bushbuck (Tragelaphus scriptus) and giraffe (Giraffa camelopardalis) in the Kruger National Park, Transvaal; of African buffalo (Syncerus caffer) and nyala in the Hluhluwe Game Reserve, Natal; and of gemsbok (Oryx gazella) in the Mountain Zebra National Park, an eland in the...

The potential of forest nature reserves as refuges for biodiversity seems to be overlooked probably due their small size. These, however, may constitute important safe havens saproxylic orga...

What resources should be committed to the control of invasive species? This study is based on a survey of nature conservation and forestry authorities, wildlife trusts and private landowners which investigated the extent of the ecological and economic impacts of the invasive non-native plant Rhododendron ponticum in the British Isles. There are data on 52,000 ha of land affected by R. ponticum,...

Despite the fact that efforts to identify it empirically have largely been futile, the liquidity effect plays a central role in conventional monetary theory and policy. Recently, however, an increasing volume of empirical work [Christiano and Eichenbaum (1992a,b), Christiano,, Eichenbaum and Evans (1994a,b) and Strongin (1995)] has supported the existence of a statistically significant and econ...

Received: March 18, 2015; Accepted: March 20, 2015; Published: March 22, 2015 If you read these pages, you certainly know the seminal book by Benoit B. Mandelbrot, The Fractal Geometry of Nature (1982). In his Masterpiece, Benoit provides both a mathematical model and a description for many of the seemingly complex forms and patterns in nature, showing that fractal patterns are extremely famili...

The objective of this study was to make an inventory of the ixodid tick species infesting wild animals in three western, semi-arid nature reserves in South Africa. To this end 22 animals in the Kgalagadi Transfrontier Park, 10 in the West Coast National Park and 16 in the Karoo National Park were examined. Fourteen tick species were recovered, of which Hyalomma truncatum, Rhipicephalus exophtha...