Coherent multiresolution isosurface ray tracing

We implement and evaluate a fast ray tracing method for rendering large structured volumes. Input data is losslessly compressed into an octree, enabling residency in CPU main memory. We cast packets of coherent rays through a min/max acceleration structure within the octree, employing a slice-based technique to amortize the higher cost of compressed data access. By employing a multiresolution level of detail (LOD) scheme in conjunction with packets, coherent ray tracing can efficiently render inherently incoherent scenes of complex data. We achieve higher performance with lesser footprint than previous isosurface ray tracers, and deliver large frame buffers, smooth gradient normals and shadows at relatively lesser cost. In this context, we weigh the strengths of coherent ray tracing against those of the conventional single-ray approach, and present a system that visualizes large volumes at full data resolution on commodity computers.     

Using iterated rational filter banks within the ARSIS concept for producing 10m Landsat multispectral images

The ARSIS concept is designed to increase the spatial resolution of an image without modification of its spectral contents, by merging structures extracted from a higher resolution image of the same scene, but in a different spectral band. It makes use of wavelet transforms and multiresolution analysis. It is currently applied in an operational way with dyadic wavelet transforms that limit the merging of images whose ratio of their resolution is a power of 2. Nevertheless, provided some conditions rational discrete wavelet transforms can be approximated numerically by rational filter banks which would enable a more general merging. Indeed, in theory, the ratio of the resolution of the images to merge is a power of a certain family of rational numbers. The aim of this paper is to examine whether the use of those approximations of rational wavelet transforms are efficient within the ARSIS concept. This work relies on a particular case: the merging of a 10 m SPOT Panchromatic image and a 30 m Landsat Thematic Mapper multispectral image to synthesize 10 m multispectral image TM-HR.     

Monthly means of daily solar irradiation over Egypt estimated from satellite database and various empirical formulae

Monthly means of daily solar irradiation retrieved from the HelioClim-3 version 3 database (HC3v3), elaborated from Meteosat satellite images, were tested at 14 Egyptian stations along with the model of Yang, Koike, and Ye (YKY) and 10 empirical models (EMs) for the period 2004 to 2009. YKY and EMs were fitted to measurements from the period 1980 to 1989. Overall, HC3v3 exhibits a bias of 0.4 MJ m^?2 (i.e. 2% of the mean of the observations – similar to the best EMs). The root mean square error (RMSE) was 1.8 MJ m^?2 (9%) for HC3v3, which is lower than for most EMs. Coefficients of determination (R²) were greater than 0.9 for most models. The regression line between estimates and observations exhibits a slope of 1.01 and an intercept of 0.09 MJ m^?2 for HC3v3, reflecting a better performance than other models. HC3v3 shows remarkably constant performance as a function of irradiation or cloudiness compared with EMs and YKY. In general, HC3v3 is preferred to EMs when estimating monthly means of daily solar irradiation in Egypt. It is suggested that more effort is needed towards the validation and promotion of HC3v3 before researchers and practitioners use it rather than EMs.     

Universal access to communication and learning: the role of automatic speech recognition

This communication discusses how automatic speech recognition (ASR) can support universal access to communication and learning through the cost-effective production of text synchronised with speech and describes achievements and planned developments of the Liberated Learning Consortium to: support preferred learning and teaching styles; assist those who for cognitive, physical or sensory reasons find notetaking difficult; assist learners to manage and search online digital multimedia resources; provide automatic captioning of speech for deaf learners or when speech is not available or suitable; assist blind, visually impaired or dyslexic people to read and search material; and, assist speakers to improve their communication skills.     

The Present Status of Industrial Production and Use of Photovoltaic and Photocatalytic Solar Energy Conversion Devices

The recent revival of interest in the direct use of solar energy, which followed the 1973 oil crisis, has brought increased research and development activity in a number of areas. Some of these areas are discussed here, namely photocatalysis, photoelectrochemical cells, and photovoltaic devices. At the present time there is continuing research activity in photocatalysis for various purposes, including solar energy conversion, and there is also continuing research activity in photoelectrochemical methods. However, at the present time, photovoltaic devices are the only ones in limited terrestrial application for direct solar energy conversion into electricity.     

Evidence of latency and reactivation of both herpes simplex virus (HSV)-1 and HSV-2 in the genital region

While superinfection with different herpes simplex virus (HSV) types has been demonstrated in animals, the ability of the two HSV types to colonize and reactivate in the same anatomic region in humans has not been well demonstrated. In 6 patients, both HSV-1 and HSV-2 was recovered from genital lesions. In 4 of them, who initially acquired genital HSV-1 infection, subsequent HSV-2 infection presented as a prolonged episode of genital lesions and a marked increase in the frequency of genital recurrences. While most of the subsequent clinical reactivations were HSV-2, in 2 patients the recurrence rate of genital HSV-1 increased after the acquisition of HSV-2. These data demonstrate the ability of a second HSV type to infect the same anatomic region and illustrate the difference in reactivation frequency of the two types in the same person. Typing of HSV isolates may be useful in persons with recent alteration in recurrence rates of genital HSV.     

Theory and application of array coils in MR spectroscopy

The theory and application of array coils are reviewed in the context of phased array spectroscopy. The optimization of the signal-to-noise ratio from an array of coils is developed by considering the efficiency of a phased array transmit coil. This approach avoids the need to consider noise correlation, and should be useful in future considerations of transmit phased array coils for MR spectroscopy. Methods to characterize array coil performance, including fields and coupling are briefly summarized, along with methods to minimize the effects of mutual inductance. The signal-to-noise advantages of array coils over single coils are examined for both planar and cylindrical arrays. Numerical simulations of planar arrays of 2 x 2, 4 x 4 and 8 x 8 elements and constant overall dimension are compared to a single coil of the same size. The results demonstrate a significant improvement in sensitivity near the array coil. Although the benefits of the array decrease as a function of distance from the array, the array sensitivity never drops below that of a single coil with the same overall dimensions, or that of a single element of the array. Similar results are obtained for a sixteen element cylindrical array, which is compared to a standard quadrature birdcage coil using both computational methods and phantom measurements. The phased array techniques reviewed are demonstrated with proton spectroscopic images of the brain.     

Identification of a UPTG inhibitor protein from maize endosperm: high homology with sucrose synthase protein

A thermolabile UPTG inhibitor protein (IP) was isolated and purified from a developing maize endosperm preparation. High homology of two internal peptides of IP with known plant sucrose synthase (SS) sequences suggested that IP might be related somehow with SS. IP and SS activities were found in the same preparation and showed thermolability between 60-65 degrees C. IP and SS activities presented the same ionic charge and molecular mass in native conditions (Mono Q and Superose-12 columns chromatographies). Western blot experiments with an anti-SS antibody as well as with an anti-IP antibody showed a single 80 kDa polypeptide band where IP and SS activities were present. Anti-SS antibody can neutralize SS as well as IP activities in a neutralization assay. It was found that in the maize mutant shrunken-1, lacking SS1 protein, the UPTG activity was not inhibited. Furthermore, the solubilized preparation of the sh1 endosperm is unable of inhibiting UPTG activity from potato tuber. The high correlation between IP and SS properties suggests that IP might be in fact a form of SS. Moreover, the relation between IP and the SS1 isoform is discussed. So, a new biological activity of SS is suggested.