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

Incidence and survival rate of women with cervical cancer in the Greater Amsterdam area

To evaluate the effect of population-based cervical cancer screening on the occurrence of cervical cancer in The Netherlands, we investigated the incidence and survival of cervical cancer registered by a cancer registry in the Greater Amsterdam area. The incidence rate of squamous cell carcinoma decreased significantly from 9.2/100,000 women in 1988 to 5.9/100,000 in 2000 (P<0.001). The incidence rate of adenocarcinomas remained stable. After adjustment for age, stage and lymph node involvement, the relative risk of death was 1.6 times higher for patients with adenocarcinomas than for patients with squamous cell carcinoma (95% CI 1.2-2.1). The decreased survival was related to histological type, as the effect remained significant after correction for confounding factors. Over time, the prognosis of women with squamous cell carcinoma improved significantly. No significant change was observed for women diagnosed with adenocarcinoma. These results suggest that the screening programme in The Netherlands as executed in the Greater Amsterdam area is associated with a decreased incidence and increased survival of patients with squamous cell carcinoma, but fails to detect (pre)malignant lesions of adenocarcinoma. Since more than 92% of adenocarcinomas and its precursors contain high-risk HPV, adding HPV testing to cytologic screening might improve the present screening programme in detecting adenocarcinoma and its precursor lesions

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&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; concentrations from 200 m a.g.l. in 1992 to vertical gradients at 4 levels of the gases CO&lt;sub&gt;2&lt;/sub&gt;, CH&lt;sub&gt;4&lt;/sub&gt;, SF&lt;sub&gt;6&lt;/sub&gt;, N&lt;sub&gt;2&lt;/sub&gt;O, H&lt;sub&gt;2&lt;/sub&gt;, CO and gradients at 2 levels for &lt;sup&gt;222&lt;/sup&gt;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. &lt;br&gt;&lt;br&gt; 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&lt;sub&gt;2&lt;/sub&gt; of 1.90 ± 0.1 ppm yr&lt;sup&gt;−1&lt;/sup&gt;, for CH&lt;sub&gt;4&lt;/sub&gt; of 4.4 ± 0.6 ppb yr&lt;sup&gt;−1&lt;/sup&gt;, for N&lt;sub&gt;2&lt;/sub&gt;O of 0.86 ± 0.04 ppb yr&lt;sup&gt;−1&lt;/sup&gt;, and for SF&lt;sub&gt;6&lt;/sub&gt; of 0.27 ± 0.01 ppt yr&lt;sup&gt;−1&lt;/sup&gt;; for CO no significant trend could be detected. &lt;br&gt;&lt;br&gt; 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&lt;sub&gt;2&lt;/sub&gt; is 25–30 ppm (higher value for lower sampling levels). The observed CH&lt;sub&gt;4&lt;/sub&gt; seasonal amplitude is 50–110 ppb. All gases except N&lt;sub&gt;2&lt;/sub&gt;O show highest concentrations in winter and lower concentrations in summer, N&lt;sub&gt;2&lt;/sub&gt;O observations show two additional concentration maxima in early summer and in autumn. &lt;br&gt;&lt;br&gt; 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&lt;sub&gt;2&lt;/sub&gt; 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

COMET: a Lagrangian transport model for greenhouse gas emission estimation ? forward model technique and performance for methane

International audienceThe Lagrangian transport model COMET has been developed to evaluate emission estimates based on atmospheric concentration observations. This paper describes the model and its application in modelling the methane concentrations at the European stations Cabauw and Macehead. The COMET model captures in most cases both synoptic and diurnal variations of the concentrations as a function of time and in absolute size quite well. The explained variability by COMET of the mixed layer concentration for Cabauw varies from 50% to 84%; for all hourly observations in 2002 the explained variability is 71% with a RMSE of 112 ppb. The explained variability for Macehead is 48%. The most important model parameters were tested for their influence on model performance, but in general the model is not very sensitive to variations within acceptable limits. For a regionally and locally polluted continental site the COMET model shows only a small bias and a moderate random error, and therefore is considered to capture the influence of the sources on the concentration variations quite well. It is therefore concluded that inverse methods and more specifically the COMET model is suitable to be applied in deriving independent estimates of greenhouse gas emissions using Source-Receptor relationships

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

Werking van sexferomoon van jeneverbesmineermot in de praktijk

Het doel is een bruikbare methode voor de praktijk om de vlucht van jeneverbesmineermot vast te stellen. Wanneer vastgesteld kan worden dat de jeneverbesmineermot actief is kan gericht een bestrijding worden uitgevoerd. Er is voor deze proef gebruik gemaakt van aangetaste jeneverbesstruiken op drie verschillende locaties. De locaties waren de collectietuin van PPO Boskoop, PPO Naaldwijk en op de kwekerij van Koos Buitenhuis te Boskoop. De feromoonvallen met codering A t/m G vingen weinig mannetjes van jeneverbesmineermot. Nog tijdens deze vlucht is de samenstelling van het feromoon aan de hand van de laatste resultaten van het laboratoriumonderzoek met mannetjes verbetert. De nieuwe formuleringen met coderingen K, L en M (dezelfde componenten in verschillende verhoudingen) leverden een grote vangst van jeneverbesmineermot op

pH-Channeling in Cancer: How pH-Dependence of Cation Channels Shapes Cancer Pathophysiology.

Tissue acidosis plays a pivotal role in tumor progression: in particular, interstitial acidosis promotes tumor cell invasion, and is a major contributor to the dysregulation of tumor immunity and tumor stromal cells. The cell membrane and integral membrane proteins commonly act as important sensors and transducers of altered pH. Cell adhesion molecules and cation channels are prominent membrane proteins, the majority of which is regulated by protons. The pathophysiological consequences of proton-sensitive ion channel function in cancer, however, are scarcely considered in the literature. Thus, the main focus of this review is to highlight possible events in tumor progression and tumor immunity where the pH sensitivity of cation channels could be of great importance

Proper weak-coupling approach to the periodic s-d(f) exchange model

The periodic s-d(f) exchange model is characterized by a wide variety of interesting applications, a simple mathematical structure and a limited number of reliable approximations which take care of the quantum nature of the participating spins. We suggest the use of a projection-operator method for getting information perturbationally, which are not accessible via diagrammatic approaches. In this paper we present in particular results beyond perturbation theory, which are obtained such that almost all exactly known limiting cases are incorporated correctly. We discuss a variety of possible methods and evaluate their consequences for one-particle properties. These considerations serve as a guideline for a more effective approach to the model.Comment: 11 pages, 6 figures; accepted by Phys. Rev.