Reflectance based object recognition

Neighboring points on a smoothly curved surface have similar surface normals and illumination conditions. Therefore, their brightness values can be used to compute the ratio of their reflectance coefficients. Based on this observation, we develop an algorithm that estimates a reflectance ratio for each region in an image with respect to its background. The algorithm is efficient as it computes ratios for all image regions in just two raster scans. The region reflectance ratio represents a physical property that is invariant to illumination and imaging parameters. Several experiments are conducted to demonstrate the accuracy and robustness of ratio invariant.The ratio invariant is used to recognize objects from a single brightness image of a scene. Object models are automatically acquired and represented using a hash table. Recognition and pose estimation algorithms are presented that use ratio estimates of scene regions as well as their geometric properties to index the hash table. The result is a hypothesis for the existence of an object in the image. This hypothesis is verified using the ratios and locations of other regions in the scene. This approach to recognition is effective for objects with printed characters and pictures. Recognition experiments are conducted on images with illumination variations, occlusions, and shadows. The paper is concluded with a discussion on the simultaneous use of reflectance and geometry for visual perception.     

Mechanism of Oxygen Diffusion in Glassmelts Containing Variable-Valence Ions

A mechanism is proposed to describe the influence of redox reactions, which involve variable-valence ions, on the diffusional mass transport of molecular dissolved oxygen in glassmelts. The concentration profile for molecular dissolved oxygen in a melt with diffusional transport in one direction in a Cartesian coordinate system is described by a differential equation: ∂(O₂/∂ t = D_c (∂²[O₂]/∂ x ²), where D_c depends on the actual value of the diffusivity D of physically dissolved oxygen, the local molecular oxygen concentration, the concentration of variable-valence ions, and the equilibrium constant for the relevant redox reaction. This equation is applicable for diffusion into or outwards from the melt from or into the furnace atmosphere. It is shown here that the value of D_c is always less than D . Concentration profiles for diffusing oxygen in glassmelts with refining agents (containing variable-valence ions) are thus steeper than profiles in melts without refining agents. A decrease in temperature of a glassmelt with variable-valence ions generally leads to diffusion of oxygen into the melt. The flux of oxygen gas into (oxidation) or out (reduction) of the melt is proportional to ( D/D_c )^1/2 and is enhanced by the effect of variable-valence ions dissolved in the melt.     

Evidence for the involvement of tyrosine-69 in the control of stereospecificity of porcine pancreatic phospholipase A2

We have studied the role of Tyr-69 of porcine pancreatic phospholipaseA₂ in catalysis and substrate binding, using site-directed mutagenesis.A mutant was constructed containing Phe at position 69. Kineticcharacterization revealed that the Phe-69 mutant has retainedenzymatic activity on monomeric and micellar substrates, andthat the mutation has only minor effects on k_cat and K_m. Thisshows that Tyr-69 plays no role in the true catalytic eventsduring substrate hydrolysis. In contrast, the mutation has aprofound influence on the stereospecificity of the enzyme. Whereasthe wild-type phospholipase A₂ is only able to catalyse thedegradation of sn-3 phospholipids, the Phe-69 mutant hydrolysesboth the sn-3 isomers and, at a low (1–2%) rate, the sn-1isomers. Despite the fact that the stereospecificity of themutant phospholipase has been altered, Phe-69 phospholipasestill requires Ca²⁺ ions as a cofactor and also retains itsspecificity for the sn-2 ester bond. Our data suggest that inporcine pancreatic phospholipase A₂ the hydroxyl group of Tyr-69serves to fix and orient the phosphate group of phospholipidmonomers by hydrogen bonding. Because no such interaction canoccur between the Phe-69 side-chain and the phosphate moietyof the substrate monomer, the mutant enzyme loses part of itsstereospecificity but not its positional specificity.     

Risk-based rules for crane safety systems

The International Maritime Organisation (IMO) has recommended a method called formal safety assessment (FSA) for future development of rules and regulations. The FSA method has been applied in a pilot research project for development of risk-based rules and functional requirements for systems and components for offshore crane systems. This paper reports some developments in the project. A method for estimating target reliability for the risk-control options (safety functions) by means of the cost/benefit decision criterion has been developed in the project and is presented in this paper. Finally, a structure for risk-based rules is proposed and presented.     

An investigation of the catalytic abatement of emissions from the combustion of diesel/bioethanol blends

In this study, we investigated the activity of pre-sulfated 1%Pt–2%Sn/γ–Al₂O₃ on the catalytic abatement of the combustion emissions of three fuels: pure diesel E(0), pure bioethanol E(100) and bioethanol blended diesel containing 10% bioethanol E(10). The emissions generated, by each blend combustion, were conducted continuously to the catalyst sample. The catalytic activity was determined by following the evolution of the outflow emissions concentrations by FTIR gas spectroscopy as a function of the catalyst temperature. Results showed that the addition of bioethanol to diesel may be necessary to enhance the catalytic oxidation of diesel unburned hydrocarbons and particulate matter on pre-sulfated 1%Pt–2%Sn/γ–Al₂O₃.     

Pathway and single gene analyses of inhibited Caco-2 differentiation by ascorbate-stabilized quercetin suggest enhancement of cellular processes associated with development of colon cancer

The aim was to investigate mechanisms contributing to quercetin's previously described effects on cell-proliferation and -differentiation, which contradicted its proposed anticarcinogenic potency. In a 10-day experiment, 40 microM quercetin stabilized by 1 mM ascorbate reduced Caco-2 differentiation up to 50% (p < 0.001). Caco-2 RNA from days 5 and 10, hybridized on HG-U133A2.0 Affymetrix GeneChips(R), showed 1,743 affected genes on both days (p < 0.01). All 14 Caco-2 differentiation-associated genes showed decreased expression (p < 0.01), including intestinal alkaline phosphatase, that was confirmed technically (qRT-PCR) and functionally (enzyme-activity). The 1,743 genes contributed to 27 pathways (p < 0.05) categorized under six gene ontology (GO) processes, including apoptosis and cell-cycle. Genes within these GO-processes showed fold changes that suggest increased cell-survival and -proliferation. Furthermore, quercetin down-regulated expression of genes involved in tumor-suppression and phase II metabolism, and up-regulated oncogenes. Gene expression changes mediated by ascorbate-stabilized quercetin were concordant with those occurring in human colorectal carcinogenesis ( approximately 80-90%), but were opposite to those previously described for Caco-2 cells exposed to quercetin without ascorbate ( approximately 75-90%). In conclusion, gene expression among Caco-2 cells exposed to ascorbate-stabilized quercetin showed mechanisms contrary to what is expected for a cancer-preventive agent. Whether this unexpected in vitro effect is relevant in vivo, remains to be elucidated.     

Identification and characterization of a novel cap-binding protein from Arabidopsis thaliana

Cap-binding proteins specifically bind to the 7-methyl guanosine (m7G) functional group at the 5' end of eukaryotic mRNAs. A novel Arabidopsis thaliana protein has been identified that has sequence similarity to cap-binding proteins but is clearly a different form of the protein. The most obvious primary sequence difference is the substitution of two of the eight conserved tryptophan residues with other aromatic amino acids in the novel protein. Analogous forms of this novel protein appear to be present in other higher eukaryotes but not in yeast. Analysis of the native and recombinant forms of the novel protein by retention on m7GTP-Sepharose indicate that it is a functional cap-binding protein. Measurements of the dissociation constant for this protein indicate that it binds m7GTP 5-20-fold tighter than eukaryotic initiation factor (eIF)(iso)4E. The novel protein also supports the initiation of translation of capped mRNA in vitro. Biochemical analysis and yeast two-hybrid data indicate that it interacts with eIF(iso)4G to form a complex. Based on these observations, this protein appears to be able to function as a cap-binding protein and is given the designation of novel cap-binding protein (nCBP).     

Ultrasonic characterization of the effect of cold work and grain size in copper and 68:32 brass sheets

The effectiveness of ultrasonic velocity measurements was evaluated as a means for nondestructive characterization of cold-rolled copper and 68:32 brass sheets. An apparatus was designed to generate and receive the zeroth symmetrical mode of ultrasonic Lamb waves in thin copper and brass sheets. The effect of angular variations in propagation direction with respect to the rolling direction on the measured Lamb wave velocities is shown. Interpretation of the variations of ultrasonic Lamb wave velocity were related to deformation mechanisms and texture development in copper and 68:32 brass sheets. Results show that the grain size and cold work influence the velocity as well as the texture of copper and 68:32 brass sheets. Results indicate the possibility of using ultrasonic Lamb wave velocity as a tool to monitor elastic anisotropy.     

Chromium speciation in coal and biomass co-combustion products

Chromium speciation is vital for the toxicity of products resulting from co-combustion of coal and biomass. Therefore, understanding of formation processes has been studied using a combination of X-ray absorption fine structure (XAFS) spectroscopy and thermodynamic equilibrium calculations. The influence of cofiring on Cr speciation is very dependent on the type of fuel. Cr(VI) contents in the investigated fly ash samples from coal and cofiring average around 7% of the total chromium. An exception is cofiring 7-28% wood for which ashes exhibited Cr(VI) concentrations of 12-16% of the total chromium. Measurements are in line with thermodynamic predictions: RE factors of Cr around 1 are in line with volatile Cr only above 1400 °C; lower Cr(VI) concentrations with lower oxygen content and Cr(III) dissolved in aluminosilicate glass. Stability of Cr(VI) below 700 °C does not correlate with Cr(VI) concentrations found in the combustion products. It is indicated that Cr(VI) formation is a high-temperature process dependent on Cr evaporation (mode of occurrence in fuel, promoted by organic association), oxidation (local oxygen content), and formation of solid chromates (promoted by presence of free lime (CaO) in the ash). CaCrO(4)(s) is a probable chemical form but, given different leachable fractions (varying from 25 to 100%), different forms of Cr(VI) must be present. Clay-bound Cr is likely to dissolve in the aluminosilicate glass phase during melting of the clay.     

Optimal placement of probes for dynamic pressure measurements in large-scale fluidized beds

Pressure data sampled at sufficiently high frequency (typically 20 Hz or higher) can yield much information about the hydrodynamic state of a fluidized bed. Since part of the pressure waves travelling through large (industrial) fluidized beds is only detectable in a limited area of the bed, pressure measurements need to be performed at several positions to cover the whole bed. We examine these local pressure waves (caused by, e.g., passing bubbles or coalescing bubbles) in a 0.80 m i.d. bubbling fluidized bed of Geldart B particles. Experiments and simulations are performed to determine the intensity decrease as local pressure waves propagate from their origin. A new spectral method is applied to determine the degree of coherence for pressure signals measured at two different positions in a fluidized bed. For a superficial gas velocity of 5u_mf, local pressure waves can be detected up to a radial distance of about 0.5 m from their origin; this distance is somewhat lower for lower gas velocities. This means that the radial spacing of pressure probes should not exceed 1 m. For large diameter beds with a bed height below 1.5 m, a set of probes at a single level and at several radial positions is sufficient to observe or monitor the dynamic state of the complete bed; the probes should preferably be placed at a height of 30% to 40% of the total bed height.