Motion of points and lines in the uncalibrated case

In the present paper we address the problem of computing structure and motion, given a set point and/or line correspondences, in a monocular image sequence, when the camera is not calibrated.Considering point correspondences first, we analyse how to parameterize the retinal correspondences, in function of the chosen geometry: Euclidean, affine or projective geometry. The simplest of these parameterizations is called the FQs-representation and is a composite projective representation. The main result is that considering N+1 views in such a monocular image sequence, the retinal correspondences are parameterized by 11 N–4 parameters in the general projective case. Moreover, 3 other parameters are required to work in the affine case and 5 additional parameters in the Euclidean case. These 8 parameters are calibration parameters and must be calculated considering at least 8 external informations or constraints. The method being constructive, all these representations are made explicit.Then, considering line correspondences, we show how the the same parameterizations can be used when we analyse the motion of lines, in the uncalibrated case. The case of three views is extensively studied and a geometrical interpretation is proposed, introducing the notion of trifocal geometry which generalizes the well known epipolar geometry. It is also discussed how to introduce line correspondences, in a framework based on point correspondences, using the same equations.Finally, considering the F Qs-representation, one implementation is proposed as a motion module, taking retinal correspondences as input, and providing and estimation of the 11 N–4 retinal motion parameters. As discussed in this paper, this module can also estimate the 3D depth of the points up to an affine and projective transformation, defined by the 8 parameters identified in the first section. Experimental results are provided.     

In vitro interactions between DMSA-coated maghemite nanoparticles and human fibroblasts: A physicochemical and cyto-genotoxical study

Although the current production of oxide nanoparticles may be modest, the wide range of proposed applications and forecasted growth in production has raised questions about the potential impact of these nanoparticles on the environment and human health. Iron oxide nanoparticles have been proposed for an increasing number of biomedical applications although in vitro toxicity depending on the particles coating has been evidenced. The aim of this study was to examine the potential in vitro cyto- and genotoxicity on human dermal fibroblasts of DMSA-coated maghemite nanoparticles (NmDMSA) as a function of well-defined physicochemical states. Well-stabilized NmDMSA produced weak cytotoxic and no genotoxic effects. This is attributed in part to the DMSA coating, which serves as a barrier for a direct contact between nano-oxide and fibroblasts, inhibiting a potential toxic effect.     

MIM零件烧结过程中收缩和变形的数值模拟

为描述金属粉末注射成形坯件在烧结过程中的收缩和变形行为,基于连续介质力学原理建立了符合粘塑性本构关系的宏观烧结模型。该模型通过有限元软件Abaqus的用户子程序实现,进行烧结过程的数值模拟。分析了由于坯件重力、非均匀初始密度分布以及坯件支承体之间的摩擦力等因素而引起的非均匀收缩和变形。通过与试验结果的比较,验证了烧结模型和数值方法的正确性。     

Effects of 1,4-Benzoxazin-3-One Derivatives from Maize on Survival and Fecundity of Metopolophium dirhodum (Walker) on Artificial Diet

Effects of 2--D-glucopyranosyloxy-4-hydroxy-7-methoxy-1,4benzoxazin-3-one (DIMBOA-Glc) and DIMBOA-Glc N-O-methylated (HDMBOA-Glc), two compounds present in high concentration in maize, were tested on the aphid Metopolophium dirhodum reared on artificial diet. HDMBOA-Glc and DIMBOA-Glc decrease survival of adults with an LD₅₀ of 1 mM and 5.6 mM, respectively, after 72 hr of feeding. These compounds also decrease the fecundity of the aphids at concentrations of 2 mM and 1 mM, respectively. At concentrations of 2 mM HDMBOA-Glc and 8 mM DIMBOA-Glc in the diet, the average lifetime fecundity of 10 females is near zero. Offspring mortality on diet with 2 mM DIMBOA-Glc is significantly higher than with the control diet. In contrast, HDMBOA-Glc has no effect on the survival of offspring. The possibility that these compounds protect Poaceae against aphids is discussed.     

Investigation on Convective Drying of Mixtures of Sewage Sludge and Sawdust in a Fixed Bed

This work is part of a project aiming to develop a renewable fuel for gasification purposes, through convective drying of sludge/wood mixtures. The first step consists of characterizing the behavior of sawdust/sludge mixtures during the application of convective drying. The influence of the mixing step (no mixing versus 30 s at 40 rpm), as well as the sawdust : sludge ratio (1:9, 2:8, 3:7, and 4:6 on a dry basis) and the effect of drying temperature (50, 80, and 110°C) were investigated. In this study, X-ray tomography, a noninvasive imaging technique, is used to assess changes in the volume, void, and exchange surface at the beginning and the end of the drying process. Results first confirm the importance of the mixing step on the drying behavior: the drying rate of the mixed sludge is lower than that of the original sludge. Nevertheless, the addition of sawdust is shown to have a positive impact on the drying process from a mass ratio of 2:8, with drying rates higher than that of the original sludge. With increasing amounts of sawdust, the initial and final bed volumes, initial and final total exchange surfaces, and initial void fraction increase linearly, but the bed volume shrinkage and final void fraction decrease linearly.     

Profiling hospitals based on emergency readmission: a multilevel transition modelling approach

Emergency readmission is seen as an important part of the United Kingdom government policy to improve the quality of care that patients receive. In this context, patients and the public have the right to know how well different health organizations are performing. Most methods for profiling estimate the expected numbers of adverse outcomes (e.g. readmission, mortality) for each organization. A number of statistical concerns have been raised, such as the differences in hospital sizes and the unavailability of relevant data for risk adjustment. Having recognized these statistical concerns, a new framework known as the multilevel transition model is developed. Hospital specific propensities of the first, second and further readmissions are considered to be measures of performance, where these measures are used to define a new performance index. During the period 1997 and 2004, the national (English) hospital episodes statistics dataset comprise more than 5 million patient readmissions. Implementing a multilevel model using the complete population dataset could possibly take weeks to estimate the parameters. To resolve the problem, we extract 1000 random samples from the original data, where each random sample is likely to lead to differing hospital performance measures. For computational efficiency a Grid implementation of the model is developed. Analysing the output from the full 1000 sample, we noticed that 4 out of the 5 worst performing hospitals treating cancer patients were in London. These hospitals are known to be the leading NHS Trusts in England, providing diverse range of services to complex patients, and therefore it is inevitable to expect higher numbers of emergency readmissions.     

Modulation of the enzymatic activity of papain by interdomain residues remote from the active site

The two main catalytic residues Cys25 and Hisl59 of the monomericcysteine protease papain are located on different walls of acleft formed by two domains. This topology suggests a possiblerelationship between relative domain organization and catalyticmechanism. The effect on enzymatic parameters of structuralmodifications at various locations of the twodomain interfaceof papain was examined by individual or double replacementsby Ala of pairs of interacting residues. Most modificationshad no effect on enzyme activity. However, the enzyme's substrateturnover (k_cat) decreased following simultaneous alterationof the two most conserved residues, forming an apolar contactlocated 15 Å away from the active site. The pH activityprofile of the double mutant was unchanged, indicating a conservedionization state of the active site thiolate-imidazolium ionpair. This state is strongly dependent on the distance separatingthe two residues, thus suggesting that the active site geometryhas not been significantly altered. Efficient enzymatic activityin papain requires more than a correct active site geometryand is influenced by domain packing properties in a region remotefrom the active site.     

Syntheses of poly[N-(2,2 dimethoxyethyl)-N-methyl acrylamide] for the immobilization of oligonucleotides

Radical-initiated polymerization of N-(2,2 dimethoxyethyl)-N-methylacrylamide has been carried out either in chloroform or methanol using 2,2′-azobisisobutyronitrile as an initiator, allowing us to prepare acetal containing water-soluble polymers. A kinetic study in both solvents showed that this monomer fairly homopolymerized (k_p · k_t^−1/2 = 1 mol^−1/2 L^1/2 s^−1/2). Static light scattering was used to characterize the molecular weight of these polymers. In addition, the Mark–Houwink–Sakurada relationship was established based on viscosity measurements performed at 25°C in water. Recovery of the aldehyde moieties on the polymer was achieved under mild conditions using a diluted inorganic solution. The analysis of the formation of aldehyde groups was performed by ¹H- and ¹³C-NMR. The covalent binding of oligodeoxyribonucleotides was carried out in water/acetonitrile mixtures with subsequent NaBH₄ reduction of the imine bonds so as to stabilize the polymer/oligodeoxynucleotide conjugates. © 1996 John Wiley & Sons, Inc.     

Design of an antibacterial gelatin based on a covalent protein–protein coupling

An antibacterial peptide (AMP), i.e., nisin, was covalently bound to gelatin through a protein–protein coupling. Various reaction conditions were tested to study and optimize parameters of grafting e.g., orientation and density of AMP, which could impact the final antibacterial activity of the modified biopolymer. Modification was investigated by Fourier transform infrared (FT‐IR) spectroscopy and zeta potential. The antibacterial activity of the nisin‐enriched gelatin was evaluated against two staphylococci bacterial strains, i.e., Staphylococus epidermidis and Staphylococcus aureus. A higher activity was found for gelatin modified at pH = 7.4 revealing an influence of the nisin orientation on the protein antibacterial property. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41825.     

Transferring the calibration of direct solar irradiance to diffuse-sky radiance measurements for CIMEL Sun-sky radiometers

Two types of sunphotometric measurement are considered in this study: direct-Sun irradiance and diffuse-sky radiance. Based on CIMEL CE318 Sun-sky radiometer characteristics, we introduce a gain-corrected solid angle that allows interconverting calibration coefficients of these two types of measurement, thus realizing a "vicarious" radiance calibration. The accuracy of the gain-corrected solid angle depends on the number of available historical calibration records. The method is easy to use, provided that at least one laboratory calibration has been made previously. Examples coming from three distinct CE318 versions belonging to the AERONET/PHOTONS network are presented to provide details on the vicarious calibration method and protocols. From the error propagation analysis and the comparison with laboratory results, the uncertainty of the vicarious radiance calibration is shown to be comparable with the laboratory one, e.g., 3%-5%.