Flight experience of the Compact High Resolution Imaging Spectrometer (CHRIS).

This paper describes the initial flight experience of the Compact High Resolution Imaging Spectrometer (CHRIS) developed at Sira Electro-Optics Ltd. The imaging spectrometer is flying on PROBA, a small agile satellite, which was launched in October 2001. The main purpose of the instrument is to provide images of land areas. The platform provides pointing in both across-track and along-track directions, for target acquisition and multi-angle observations, particularly for measurement of the Bi-directional Reflectance Distribution Function (BRDF) properties of selected targets. The platform also provides pitch motion compensation during imaging in order to increase the integration time of the instrument, increasing the number of spectral bands that can be read and enhancing radiometric resolution. The instrument covers a spectral range from 400nm to 1050nm, at ≤11nm resolution. The spatial sampling interval at perigee is approximately 17m. In this mode it is possible to read out 19 spectral bands. The locations and widths of the spectral bands are programmable. Selectable on-chip integration can increase the number of bands to 63 for a spatial sampling interval of 34m. The swath width imaged is 13km at perigee

Advances in classification for land cover mapping using SPOT HRV imagery

High-resolution data from the HRV (High Resolution Visible) sensors onboard the SPOT-1 satellite have been utilized for mapping semi-natural and agricultural land cover using automated digital image classification algorithms. Two methods for improving classification performance are discussed. The first technique involves the use of digital terrain information to reduce the effects of topography on spectral information while the second technique involves the classification of land-cover types using training data derived from spectral feature space. Test areas in Snowdonia and the Somerset Levels were used to evaluate the methodology and promising results were achieved. However, the low classification accuracies obtained suggest that spectral classification alone is not a suitable tool to use in the mapping of semi-natural cover types

Deep sequencing of GDF5 reveals the absence of rare variants at this important osteoarthritis susceptibility locus

Objective: The common single nucleotide polymorphism (SNP) rs143383 in the 5' untranslated region (5'UTR) of growth and differentiation factor 5 (GDF5) is strongly associated with osteoarthritis (OA) and influences GDF5 allelic expression in vitro and in the joint tissues of OA patients. This effect is modulated in cis by another common SNP, also located within the 5'UTR, whilst a common SNP in the 3'UTR influences allelic expression independent of rs143383. DNA variants can be common, rare or extremely rare/unique. To therefore enhance our understanding of the allelic architecture of this very important OA susceptibility locus we sequenced the gene for potentially functional and novel rare variants. Method: Using the Sanger method we sequenced GDF5 in 992 OA patients and 944 controls, with DNA changes identified by sequencing software. We encompassed the protein-coding region of the two GDF5 exons, both untranslated regions and approximately 100 bp of the proximal promoter of the gene. Results: We detected 13 variants. Six were extremely rare with minor allele frequencies (MAFs) of <= 0.0006. One is in a predicted transcription factor binding site in the GDF5 promoter whilst two substitute conserved amino acids. The remaining seven variants were common and are previously known variants, with MAFs ranging from 0.025 to 0.39. There was a complete absence of variants with frequencies in-between the extremely rare (n = 6) and the common (n = 7). Conclusions: This is the first report of the deep sequencing of an OA susceptibility locus. The absence of rare variants informs us that within the regions of the gene that we have sequenced GDF5 does not harbour any novel variants that are able to contribute, at a population level, to the OA association signal mediated by rs143383 nor does it harbour, at a population level, any novel variants that can influence OA susceptibility independent of rs143383. (C) 2011 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved