[Review of] Hoerder, Dirk. Cultures in Contact: World Migrations in the Second Millennium

Cultures in Contact is an ambitious tome of the annotated world history of human mass migrations both within and between national boundaries. This book provides a glorious descriptive wealth of when, where, and to a lesser extent why mass migrations have occurred across the largest and most populous regions of the planet earth over the span of the past millennium. In this regard it may serve as a valued reference work for anyone curious about the bigger picture of migration flows; however, those seeking a simplistic theoretical synthesis that would account for the myriad patterns of human migrations over the past millennium will not be much gratified by Hoerder\u27s tome. As the author highlights in his introductory chapter, human migration flows may be either voluntary or coerced and in either case must be viewed in a socio-historically specific systems context

Prevention of cervical cancer in the Netherlands : Studies on cytology and HPV infections

Meijer, C.J.L.M. [Promotor]Snijders, P.J.F. [Promotor]Rozendaal, L. [Copromotor]Kemenade, F.J. van [Copromotor

The need for a supply of high quality organic vegetable seeds

Production of high quality organic vegetable seeds encounters several challenges. Research is performed to support seed companies in producing vigorous and healthy organic vegetable seeds. Examples are provided with respect to research on seed vigour, determining critical control points to avoid disease transmission to the seeds, seed treatments with natu-ral compounds, new seed sorting techniques and enhancement of the natural plant defence. It is noticed that the restrictions in EU regulation 2092/91 on organic production are at present blocking the use of promising natural and sustainable components for seed treatments

Production of organic seeds: Status, Challenges and Prospects

General article on the requirements of organic agriculture for seed production. Beside this the organic agricultural system has other demands for organic seed since it does not use chemical control measures and uses natural fertilizers instead of chemical fertilizers. Research can offer an important contribution in the production of seed without diseases

Improvement of the quality of propagation material for organic farming system

The use of organic propagation material is obligatory according to the current EU regulations for organic production. However, frequently difficulties are en-countered regarding the availability, the costs or the quality. In the Netherlands a national research program aims at developing solutions, needed for improving the production of high quality organic propagation material. The main emphasis in the pro-gram is on the model crops cabbage, onion, wheat and potato. Individual projects within the program include epidemiological studies of seed borne dis-eases to develop disease prevention strategies, meth-ods to improve resistance of seeds and seedlings towards pathogens and methods to control silver scurf in seed potatoes, development of multi-spectral analysis and sorting techniques and methods for analysis and improvement of seed vigour. Active involvement of producers and users of the seeds or seed potatoes ensures that the results will be imple-mented in practice. The program also aims at strengthening the international collaboration, amongst others through involvement in international research projects

The asymmetric single-impurity Anderson model - the modified perturbation theory

We investigate the single-impurity Anderson model by means of the recently introduced modified perturbation theory. This approximation scheme yields reasonable results away from the symmetric case. The agreement with exactly known results for the symmetric case is checked, and results for the non-symmetric case are presented. With decreasing conduction band occupation, the breakdown of the screening of the local moment is observed. In the crossover regime between Kondo limit and mixed-valence regime, an enhanced zero-temperature susceptibility is found.Comment: 7 pages, 7 figures, to appear in Physica

Greenhouse gas observations from Cabauw Tall Tower (1992–2010)

Since 1992 semi-continuous in-situ observations of greenhouse gas concentrations have been performed at the tall tower of Cabauw (4.927° E, 51.971° N, −0.7 m a.s.l.). Through 1992 up to now, the measurement system has been gradually extended and improved in precision, starting with CO<sub>2</sub> and CH<sub>4</sub> concentrations from 200 m a.g.l. in 1992 to vertical gradients at 4 levels of the gases CO<sub>2</sub>, CH<sub>4</sub>, SF<sub>6</sub>, N<sub>2</sub>O, H<sub>2</sub>, CO and gradients at 2 levels for <sup>222</sup>Rn. In this paper the measurement systems and measurement results are described for the main greenhouse gases and CO, for the whole period. The automatic measurement system now provides half-hourly concentration gradients with a precision better than or close to the WMO recommendations. <br><br> The observations at Cabauw show a complex pattern caused by the influence of sources and sinks from a large area around the tower with significant contributions of sources and sinks at distances up to 500–700 km. The concentration footprint area of Cabauw is one the most intensive and complex source areas of greenhouse gases in the world. Despite this, annual mean trends for the most important greenhouse gases, compatible with the values derived using the global network, can be reproduced from the measured concentrations at Cabauw over the entire measurement period, with a measured increase in the period 2000–2009 for CO<sub>2</sub> of 1.90 ± 0.1 ppm yr<sup>−1</sup>, for CH<sub>4</sub> of 4.4 ± 0.6 ppb yr<sup>−1</sup>, for N<sub>2</sub>O of 0.86 ± 0.04 ppb yr<sup>−1</sup>, and for SF<sub>6</sub> of 0.27 ± 0.01 ppt yr<sup>−1</sup>; for CO no significant trend could be detected. <br><br> The influences of strong local sources and sinks are reflected in the amplitude of the mean seasonal cycles observed at Cabauw, that are larger than the mean Northern Hemisphere average; Cabauw mean seasonal amplitude for CO<sub>2</sub> is 25–30 ppm (higher value for lower sampling levels). The observed CH<sub>4</sub> seasonal amplitude is 50–110 ppb. All gases except N<sub>2</sub>O show highest concentrations in winter and lower concentrations in summer, N<sub>2</sub>O observations show two additional concentration maxima in early summer and in autumn. <br><br> Seasonal cycles of the day-time mean concentrations show that surface concentrations or high elevation concentrations alone do not give a representative value for the boundary layer concentrations, especially in winter time, but that the vertical profile data along the mast can be used to construct a useful boundary layer mean value. The variability at Cabauw in the atmospheric concentrations of CO<sub>2</sub> on time scales of minutes to hours is several ppm and is much larger than the precision of the measurements (0.1 ppm). The diurnal and synoptical variability of the concentrations at Cabauw carry information on the sources and sinks in the footprint area of the mast, that will be useful in combination with inverse atmospheric transport model to verify emission estimates and improve ecosystem models. For this purpose a network of tall tower stations like Cabauw forms a very useful addition to the existing global observing network for greenhouse gases