Characterization of a compressive imaging system using laboratory and natural light scenes.

Compressive imagers acquire images, or other optical scene information, by a series of spatially filtered intensity measurements, where the total number of measurements required depends on the desired image quality. Compressive imaging (CI) offers a versatile approach to optical sensing which can improve size, weight, and performance (SWaP) for multispectral imaging or feature-based optical sensing. Here we report the first (to our knowledge) systematic performance comparison of a CI system to a conventional focal plane imager for binary, grayscale, and natural light (visible color and infrared) scenes. We generate 1024×1024 images from a range of measurements (0.1%-100%) acquired using digital (Hadamard), grayscale (discrete cosine transform), and random (Noiselet) CI basis sets. Comparing the outcome of the compressive images to conventionally acquired images, each made using 1% of full sampling, we conclude that the Hadamard Transform offered the best performance and yielded images with comparable aesthetic quality and slightly higher spatial resolution than conventionally acquired images.

Variability of UV irradiance in Europe.

The diurnal and annual variability of solar UV radiation in Europe is described for different latitudes, seasons and different biologic weighting functions. For the description of this variability under cloudless skies the widely used one-dimensional version of the radiative transfer model UVSPEC is used. We reconfirm that the major factor influencing the diurnal and annual variability of UV irradiance is solar elevation. While ozone is a strong absorber of UV radiation its effect is relatively constant when compared with the temporal variability of clouds. We show the significant role that clouds play in modifying the UV climate by analyzing erythemal irradiance measurements from 28 stations in Europe in summer. On average, the daily erythemal dose under cloudless skies varies between 2.2 kJ m(-2) at 70 degrees N and 5.2 kJ m(-2) at 35 degrees N, whereas these values are reduced to 1.5-4.5 kJ m(-2) if clouds are included. Thus clouds significantly reduce the monthly UV irradiation, with the smallest reductions, on average, at lower latitudes, which corresponds to the fact that it is often cloudless in the Mediterranean area in summer.

HAEMATOTHERMIA: WARM-BLOODED AMNIOTES.

Abstract- An exhaustive parsimony analysis of amniote phylogeny using 97 characters has substantiated the hypothesis that mammals and birds are sister groups. This deduction is further supported by parasitological and molecular evidence. The presumed importance of "synapsid" fossils in amniote phylogeny is questioned and it is concluded that they represent a transformation series which when broken down into constit uent, monophyletic groups does not support the separation of the Mammalia from the remainder of the amniotes. Fossil members of the Haematothermia include pterosaurs and "dinosaurs" (both stem-group birds) and Dinocephalia, Dicynodontia, Gorgonopsida and Therocephalia (all stem-group mammals). The Dromaeosauridae are the most crownward stem-group birds and the Morganucodontidae the most crownward stem-group mammals. "Criticism of our conjectures is of decisive importance: by bringing out our mistakes it makes us understand the difficulties of the problem which we are trying to solve." (K. R. Popper, 1972).

Observations on green pupae in Papilio machaon L. and Pieris brassicae L.

Observations have been made and experiments performed to investigate the colour of pupae inPapilio machaon L. andPieris brassicae L.InP. machaon brown pupae are nearly always formed except when the pupation site is the foodplant, when nearly half the pupae are green. Switching experiments showed that the sensitive period was just before pupation and that the colour and texture of round foodplant stalks had a significant influence in producing green pupae.In the Cambridge stock ofP. brassicae used all non-diapause pupae are "brown" (including yellowish, ochreous, greyish forms), all diapausing pupae green. The background on which pupation occurred had no significance, nor did the photoperiod immediately preceeding pupation.The colour could, however, be changed by the food used; on artificial diet the pupae are blue or turquoise. This effect could not be reversed by the addition ofß-carotene to the diet, as might be expected. Attention is also drawn to the fact that at least one pupal colour is known to be genetic, and the possibility that the green/brown relationship with diapause in the CambridgeP. brassicae stock may be due to the rearing conditions used.