PESTICIDE REGULATION IN CALIFORNIA

A necessary condition for socially desirable regulation is that total social benefits outweigh total social costs. We report available information regarding the costs of pesticide regulation in California, and evaluate the likelihood that the generated benefits outweigh these costs. We conclude with a discussion of the implications for future policy research and reforms.Crop Production/Industries,

Unidirectional Movement Fibres from A Proprioceptive Organ of the Crab, Carcinus Maenas

1. The proprioceptive organ of the shore crab Carcinus maenas, which signals all proprioceptive sensation from the joint between propodite and dactylopodite, has been shown to contain sense cells receptive to position as well as to movement. 2. Certain cells of the organ increase their discharge frequency in response to greater degrees of flexion, while other endings respond to greater degrees of extension. Movement has little effect on the frequency of the position fibres. 3. Cells responding to movement in one direction only are present, certain ones signalling fiexion and others extension. The most sensitive undirectional movement fibres are almost completely independent of position and velocity. They provide the crab with an extremely sensitive movement sense not as yet reported in other proprioceptive mechanisms. 4. Both position-sensitive and movement-sensitive cells show a wide range of thresholds. 5. Cells which cannot be strictly classified as either position or movement sensitive have also been found. 6. By tracing the origin of the signals to the cell bodies, it appears that movement fibres have on the whole larger cell bodies than position fibres and are more proximally located. 7. Flexor and extensor movement cells appear to lie on different sides of elastic strand. 8. The question of how unidirectional sensitivity may be achieved is discussed

Existence of tracial states on reduced group C*-algebras

Let $G$ be a locally compact group. It is not always the case that its reduced C*-algebra $C^*_r(G)$ admits a tracial state. We exhibit closely related necessary and sufficient conditions for the existence of such. We gain a complete answer when $G$ compactly generated. In particular for $G$ almost connected, or more generally when $C^*_r(G)$ is nuclear, the existence of a trace is equivalent to amenability. We exhibit two examples of classes of totally disconnected groups for which $C^*_r(G)$ does not admit a tracial state.Comment: The proof of Remark 2.6 (ii) has been corrected, and a typo has been fixe

A Bose-Einstein condensate in a random potential

An optical speckle potential is used to investigate the static and dynamic properties of a Bose-Einstein condensate in the presence of disorder. For strong disorder the condensate is localized in the deep wells of the potential. With smaller levels of disorder, stripes are observed in the expanded density profile and strong damping of dipole and quadrupole oscillations is seen. Uncorrelated frequency shifts of the two modes are measured for a weak disorder and are explained using a sum-rules approach and by the numerical solution of the Gross-Pitaevskii equation

Non-financial performance measures: an empirical analysis of a change in a firm's performance measurement system

Groot, T.L.C.M. [Promotor

Status of National Open Spatial Data Infrastructures: a Comparison Across Continents

The increasing need for geospatial information demands for well-organised management among all levels of society. A Spatial Data Infrastructure (SDI) is a multidisciplinary and dynamic instrument that facilitates access and sharing of geospatial information. The current trend towards open data initiatives is influencing the development of these infrastructures. In order to examine this effect, this article addresses the following question: what is the current state of SDI openness of four best practice open data countries Canada, The Netherlands, Australia and Brazil, and how do they compare? The question is answered through a qualitative literature study and the application of a newly developed Open SDI Assessment Framework to the countries. The Netherlands and Canada show a high performance on all assessment dimensions; data discovery, data access and data properties. Australia and Brazil show a poor open SDI performance, as they could not meet the requirements set for the assessed datasets. General conclusions of the assessment are that data is currently fragmented and scattered among the web in all four countries, which strongly negatively influences the user experience. It is crucial that a strict legal framework is embedded in a country, which ensures that current SDI objectives and propositions regarding an user-centred approach and open data availability are achieved

Effect of optical disorder and single defects on the expansion of a Bose-Einstein condensate in a one-dimensional waveguide

We investigate the one-dimensional expansion of a Bose-Einstein condensate in an optical guide in the presence of a random potential created with optical speckles. With the speckle the expansion of the condensate is strongly inhibited. A detailed investigation has been carried out varying the experimental conditions and checking the expansion when a single optical defect is present. The experimental results are in good agreement with numerical calculations based on the Gross-Pitaevskii equation.Comment: 5 pages, 5 figure