A Compositional Framework for Hardware/Software Co-Design

We describe a compositional framework, together with its supporting toolset, for hardware/software co-design. Our framework is an integration of a formal approach within a traditional design flow. The formal approach is based on Interval Temporal Logic and its executable subset, Tempura. Refinement is the key element in our framework because it will derivefrom a single formal specification of the system the software and hardware parts of the implementation, while preserving all properties of the system specification. During refinement simulation is used to choose the appropriate refinement rules, which are applied automatically in the HOL system. The framework is illustrated with two case studies. The work presented is part of a UK collaborative research project between the Software Technology Research Laboratory at the De Montfort University and the Oxford University Computing Laboratory.     

Description and simulation of an active imaging technique utilizing two speckle fields: root reconstructors

Quasi-monochromatic light will form laser speckle upon reflection from a rough object. This laser speckle provides information about the shape of the illuminated object. Further information can be obtained if two colors of coherent light are used, provided that the colors are sufficiently close in wavelength that the interference is also measurable. It is shown that no more than two intensities of two speckle patterns and their interference are required to produce an unambiguous band-limited image of an object, to within an overall spatial translation of the image, in the absence of measurement errors and in the case where all roots of both fields and their complex conjugates are distinct. This result is proven with a root-matching technique, which treats the electric fields as polynomials in the pupil plane, the coefficients of which form the desired complex object. Several root-matching algorithms are developed and tested. These algorithms are generally slow and sensitive to noise. So motivated, several other techniques are applied to the problem, including phase retrieval, expectation maximization, and probability maximization in a sequel paper [J. Opt. Soc. Am. A 19, 458 (2002)]. The phase-retrieval and expectation-maximization techniques proved to be most effective for reconstructions of complex objects larger than 10 pixels across.     

Fuel constituent effects on fuel reforming properties for fuel cell applications

The effect of different types of compounds commonly found in diesel fuel (e.g., paraffins, naphthenes, and aromatics), as well as their chemical structure (e.g., branched versus linear paraffins) on fuel reforming has been investigated. Diesel reforming is very complicated because diesel is a complex mixture of hundreds of compounds with greatly different reactivities. The syngas production rates at the same conditions were observed in this order: paraffins > naphthenes ? aromatics. Additionally, the type of reforming performed (OSR, CPOX, or SR) as well as the process parameters (space velocity and reaction temperature) significantly affected the syngas production rates as well as carbon formation. The reactivity of one fuel component can affect the conversion pattern of others, e.g., overall yields from the reforming of a fuel mixture are not additive of yields from individual fuel components, rather the more reactive component is consumed first. Furthermore, the type of substituent in aromatics and naphthenes, the carbon chain length in n-paraffins, branching in paraffins, and degree of aromatic saturation affect the overall hydrocarbon conversion, syngas selectivity, and carbon formation. The presence of sulfur compounds in the fuel caused significant drops in H₂ yields compared to CO yields.     

Group velocity dispersion of dyes in solution measured with white-light interferometry

The group velocity dispersion (GVD) coefficient of four different dyes in solution is measured as a function of wavelength and concentration using a white-light Michelson interferometer. We find that the wavelength dependence of the GVD can be considerably different at wavelengths above and below the absorption resonance in a dye. Above the absorption resonance, the dye molecules can make a strong, wavelength-dependent contribution to the GVD of the solution. Below the absorption resonance, the dye molecules tend to contribute negligibly to the GVD of the solution. We find that the contribution of the dye molecules to the GVD can be modeled quite accurately using a simple Lorentz model with parameters set using the measured linear absorption properties of the dye.     

Safety, functionality and acceptability of a prototype polyurethane condom

The distribution of serotonin immunoreactive elements in the peripheral nervous system of three earthworm species (Lumbricus terrestris, Eisenia fetida and Tubifex tubifex) was studied using the peroxidase-antiperoxidase method. Most parts of the peripheral nervous system contain immunoreactive fibers. All segmental nerves as well as branches of the prostomial nerves show strong immunoreactivity. Muscles of the body wall contain serotonergic fibers, mostly between the circular and longitudinal layers. The best supplied area is the buccal musculature. All parts of the enteric nervous system contain serotonergic fibers, strongest staining was observed in the buccal and pharyngeal walls. Along the wall of the calciferous glands thin immunoreactive fibers were found. The excretory system, the metanephridial tubules also display immunoreactivity. Under the surface epithelium, a serotonergic subepidermal plexus was observed. No significant differences were observed between the species studied. On the basis of our morphological findings and functional studies performed by other authors it is suggested that serotonin plays an essential role in the function of the peripheral nervous system in Oligochaeta.     

Catalytic oxidation of methane over hexaaluminates and hexaaluminate-supported Pd catalysts

An aqueous (NH₄)₂CO₃ coprecipitation method, based on that of Groppi et al. [Appl. Catal. A 104 (1993) 101–108] was used to synthesize Sr_1−xLa_xMnAl₁₁O₁₉₋ hexaaluminates. These materials were first synthesized by alkoxide hydrolysis. This synthesis route requires special handling of the starting materials and is not likely to be commercially practical. The materials prepared by (NH₄)₂CO₃ coprecipitation have similar surface areas as those prepared by the alkoxide hydrolysis method. Their CH₄ oxidation activity, measured as the temperature needed for 10% conversion of methane, is higher than those prepared by alkoxide hydrolysis. The La-substantiated material, LaMnAl₁₁O₁₉₋, shows high surface area with 19.3 m²/g after calcination at 1400°C for 2 h. It is active for CH₄ oxidation with T_10% at 450°C using 1% CH₄ in air and 70 000 cm³/h g space velocity. The stability and activity of LaMnAl₁₁O₁₉₋ prepared by (NH₄)₂CO₃ coprecipitation method is a simple and important step forward for the application of CH₄ catalytic combustion for gas turbines.     

The predictability of periodontal treatment as measured by tooth loss: a retrospective study

OBJECTIVE: To analyse the validity of the Micraltest and Microbumintest semi-quantitative methods for microalbuminuria screening in type 2 diabetes mellitus in primary care clinics. DESIGN: Crossover study to validate diagnostic tests. SETTING: Three general practices at an urban health centre. PATIENTS: Consecutive sample of 64 diabetics not dependent on insulin. MEASUREMENTS AND MAIN RESULTS: Each patient's own doctor performed in the consultation the semi-quantitative determinations in a simple sample of the morning's first urine. As standard, a rate of albumin excretion above 20 micrograms/min, determined by immunonephelometry in a 2-hour controlled time sample, was used. The prevalence of Microalbuminuria was 25% (C.I. 95%, 14.4-35.6). The sensitivity of Micraltest was 69% (CI, 42-88), and its specificity 52% (CI, 37-67), corresponding to the cut-off point of 10 mg/L. The sensitivity of Microbumintest was 63% (CI, 36-84), and its specificity 67% (CI, 52-79). The combination of both tests in one sample had 75% sensitivity (CI, 47-92) and 44% specificity (CI, 30-59). Negative predictive values ranged between 84 and 85%. CONCLUSIONS: The semi-quantitative microalbuminuria detection tests are of limited use in the primary care clinic. Their sensitivity and the negative predictive value obtained in an isolated sample do not seem acceptable for a screening method.