De stand van de veredeling bij spinazie

The state of spinach breeding, including the author's work at the Institute of Horticultural Plant Breeding, Wageningen, was reviewed.Certain crossing combinations had a favourable effect on the yield. The possibility of combining resistance to Peronospora spinaciae (Mont.) de Bary and mosaic (Cucumus-virus 1) made the breeding of hybrid varieties still more attractive. The work required for the removal of all male and intersexual plants from the mother variety was a serious handicap.Experiments on influencing the sex ratio and the recognition of pollen-bearing plants some time before they flower in the mother variety gave no cause for optimism. However, it was possible to breed a practically completely female first filial generation. The combination of this first filial generation as a round seeded mother variety with a prickly seeded father could bring the possibility of growing hybrid seed on a commercial scale very much nearer. Research in the field of hybrid varieties was considered to be a most important task of the research institutes.A simple method was worked out for testing young spinach plants for resistance to downy mildew, using sheets of polythene.<p/

Cavity ring-down spectroscopy of (H2O)-O-18 in the range 16 570-17 120 cm(-1)

Cavity ring-down spectroscopy is used to record an absorption spectrum of (H2O)-O-18 water vapor in the 16570-17 120 cm(-1) region. In the spectrum, 596 lines are identified as belonging to (H2O)-O-18, of which 375 lines are assigned by comparing to newly calculated theoretical lines. The spectrum covers the entire 5v polyad and two new vibrational band origins, (321) at 16775.381 cm(-1) and (401) at 16854.991 cm(-1) are determined. (C) 2004 Elsevier Inc. All rights reserved

Reducing the first-order Doppler shift in a Sagnac interferometer

4p(5)p[1/2](0) transition in Kr at lambda = 212 nm. The achieved precision of 6 x 10(-10) is limited by the characteristics of the laser system. (c) 2007 Optical Society of America

Fast Simulators for Satellite Cloud Optical Centroid Pressure Retrievals, 1. Evaluation of OMI Cloud Retrievals

The cloud Optical Centroid Pressure (OCP), also known as the effective cloud pressure, is a satellite-derived parameter that is commonly used in trace-gas retrievals to account for the effects of clouds on near-infrared through ultraviolet radiance measurements. Fast simulators are desirable to further expand the use of cloud OCP retrievals into the operational and climate communities for applications such as data assimilation and evaluation of cloud vertical structure in general circulation models. In this paper, we develop and validate fast simulators that provide estimates of the cloud OCP given a vertical profile of optical extinction. We use a pressure-weighting scheme where the weights depend upon optical parameters of clouds and/or aerosol. A cloud weighting function is easily extracted using this formulation. We then use fast simulators to compare two different satellite cloud OCP retrievals from the Ozone Monitoring Instrument (OMI) with estimates based on collocated cloud extinction profiles from a combination of CloudS at radar and MODIS visible radiance data. These comparisons are made over a wide range of conditions to provide a comprehensive validation of the OMI cloud OCP retrievals. We find generally good agreement between OMI cloud OCPs and those predicted by CloudSat. However, the OMI cloud OCPs from the two independent algorithms agree better with each other than either does with the estimates from CloudSat/MODIS. Differences between OMI cloud OCPs and those based on CloudSat/MODIS may result from undetected snow/ice at the surface, cloud 3-D effects, low altitude clouds missed by CloudSat, and the fact that CloudSat only observes a relatively small fraction of an OMI field-of-view

Three Way Comparison between Two OMI/Aura and One POLDER/PARASOL Cloud Pressure Products

The cloud pressures determined by three different algorithms, operating on reflectances measured by two space-borne instruments in the "A" train, are compared with each other. The retrieval algorithms are based on absorption in the oxygen A-band near 760 nm, absorption by a collision induced absorption in oxygen near 477nm, and the filling in of Fraunhofer lines by rotational Raman scattering. The first algorithm operates on data collected by the POLDER instrument on board PARASOL, while the latter two operate on data from the OMI instrument on board Aura. The satellites sample the same air mass within about 15 minutes. Using one month of data, the cloud pressures from the three algorithms are found to show a similar behavior, with correlation coefficients larger than 0.85 between the data sets for thick clouds. The average differences in the cloud pressure are also small, between 2 and 45 hPa, for the whole data set. For optically thin to medium thick clouds, the cloud pressure the distribution found by POLDER is very similar to that found by OMI using the O2 - O2 absorption. Somewhat larger differences are found for very thick clouds, and we hypothesise that the strong absorption in the oxygen A-band causes the POLDER instrument to retrieve lower pressures for those scenes