Activation of alphav beta3 integrin on human osteoclast-like cells stimulates adhesion and migration in response to osteopontin

Integrins mediate cell adhesion and can induce different cellular responses, including changes in intracellular pH, changes and oscillation in intracellular free calcium, and protein phosphorylation on tyrosine. During bone resorption, the integrin alphav beta3 regulates adhesion of osteoclasts to bone extracellular matrix proteins, such us osteopontin (Opn). Adhesion via alphav beta3 is followed by osteoclast polarization onto the bone surface and by the onset of bone resorption. To characterize these events at the molecular level, we investigated the state of activation of alphav beta3 on the human osteoclast-like cell line GCT23 using the monoclonal antibody AP5 which binds to and can induce, under low calcium conditions, activated alphav beta3. By flow cytometry, approximately 50% of alphav beta3 on the surface of the osteoclast-like cell line GCT23 was reactive with AP5 and was therefore in the activated state. Incubation with AP5 in the presence of low calcium concentrations increased activated alphav beta3 to 90-100%. Activation of alphav beta3 increased the efficiency of GCT23 adhesion to Opn by 2-fold. Furthermore, haptotactic migration on Opn was also enhanced about 40% compared to control. We propose that changes in the activation state of alphav beta3 may be a regulation point for osteoclasts during bone resorption.     

Finite element analysis with uncertain probabilities

This paper presents a general method for the finite element analysis of linear mechanical systems by taking into account probability density functions whose parameters are affected by fuzziness. Within this framework, the standard perturbation-based stochastic finite element method is relaxed in order to incorporate uncertain probabilities in static, dynamic and modal analyses. General formulae are provided for assessing the (fuzzy) structural reliability and several typologies of optimization problems (reliability-based design, robust design, robust/reliability-based design) are formalized. In doing this the credibility theory is extensively used to extract qualified crisp data from the available set of fuzzy results, so that standard optimizers can be adopted to solve the most important design problems. It is shown that the proposed methodology is a general and versatile tool for finite element analyses because it is able to consider, both, probabilistic and non-probabilistic sources of uncertainties, such as randomness, vagueness, ambiguity and imprecision.     

Experimental technique for reducing contact and background noise in voltage spectral density measurements

Electric noise measurements can give useful information on the conduction mechanisms and the dynamic behaviors of the charge carriers in new materials. However, it is well known that not all the electronic fluctuations are originated from the material itself, but some noise sources depend on the experimental procedures used for the measurements. In this article, an experimental technique to reduce "external" noise components, not associated with the bulk system, is presented. The proposed method is based on measurements of the voltage spectral density, using in sequence a four- and a two-probe technique. From the measurements it is possible to evaluate the contact and the background noise contributions and to recover the real spectral trace of the sample. The proposed procedure is demonstrated to be valid in spectral density measurements performed on La(0.7)Sr(0.3)MnO(3) thin films.     

Ion beam induced luminescence on white inorganic pigments for paintings

Ion beam induced luminescence (IBIL) has been used for studying the emission features and the radiation hardness of white pigments. In particular, ZnO, gypsum and basic lead sulphate pigments have been analyzed with a 3.0 MeV H⁺ beam at the AGLAE Louvre laboratory. The same pigments mixed with different binders have been also analyzed on a canvas, in order to evaluate the contribution of the binders both to the IBIL spectra and to the radiation hardness. It turns out that the binder affects both the IBIL spectra and the radiation hardness of pigments when the emission bands are related to point defects, as occurs for ZnO.     

Electrophoretic deposition of La0.6Sr0.4Co0.8Fe0.2O3−δ cathodes on Ce0.9Gd0.1O1.95 substrates for intermediate temperature solid oxide fuel cell (IT-SOFC)

Porous thick films of La_0.6Sr_0.4Co_0.8Fe_0.2O_3?δ (LSCF) on Ce_0.9Gd_0.1O_1.95 (CGO) substrates were prepared by the electrophoretic deposition (EPD) method. Organic suspensions of different compositions containing LSCF ceramic particles were investigated with the aim to determine the optimal composition of the suspension and EPD conditions. Stainless steel substrates were used in order to determine the optimal parameters for the EPD process. The best results were achieved with solutions containing acetylacetone, iodine and starch. The EPD conditions leading to uniform LSCF films were: applied voltage 20 V and deposition time 120 s, with the electrodes separated 1.5 cm. EPD was also demonstrated to be a simple and useful method for making porous LSCF cathodes on CGO substrates. It was shown that the microstructure of the films can be controlled by changing the applied voltage, deposition time and concentration of additives in suspension.     

Multibody Analysis of Controlled Aeroelastic Systems on Parallel Computers

The paper describes the application of parallel techniques to amultibody multidisciplinary formulation. The problem is stated interms of a system of nonlinear Differential-Algebraic Equations(DAE). The parallel solution is obtained using a sub-structuringdomain decomposition method, that is able to exploit thecharacteristic quasi-monodimensional topology that multibodymodels usually present. The presence of explicit constraints inform of algebraic equations requires particular care in thetreatment of the related unknowns, to avoid local singularityproblems. The code has been successfully tested on differentcomputer architectures. Special attention has been dedicated toproduce a code that will efficiently work on a cluster of PCs.Results of three test problems, regarding the simulation of anonlinear beam bending and of complex aeroservomechanical systemsas an helicopter rotor and a tiltrotor aircraft, are presented.     

Turbulent flow field comparison and related suitability for fish passage of a standard and a simplified low‐gradient vertical slot fishway

Fishways are hydraulic structures that allow passage of fish across obstructions in rivers. Vertical slot fishways—VSFs—are considered the most efficient and least selective type of technical fishway solutions, especially due to their ability to remain effective even when significant upstream and/or downstream water level fluctuations occur. The scope of the present study is to perform numerical simulations in order to investigate and compare the hydraulic turbulent flow field in a standard and a simplified version of the most common VSF design. Implications in relation to fish swimming behaviour and fish passage performance are discussed. Different water depths (as well as discharges) were investigated, using a bed slope of 5%, as a reference for low‐gradient VSFs with a very limited selectivity that can be used in multispecies rivers in grayling‐barbel regions. Results show that maximum values of velocity, turbulent kinetic energy, and Reynolds stresses are higher in the standard design. However, corresponding to slot geometry and orientation, the direction of the main jet in the simplified design is more inclined towards the left side of the pool. This causes the eddy to split into 2 smaller ones; the minimum eddy dimension is reduced from 0.4–0.5 to 0.2–0.3 m. These dimensions are detrimental for fish passage efficiency, being more comparable with fish length (0.15–0.40 m), thus affecting migrating fish stability and orientation. Furthermore, the standard design provides a more straightforward upstream path and wider areas of low flow velocities and turbulence, useful for fish resting. Therefore, it is recommended that the standard design should be preferred over its simplified version, even if its construction costs are around 10–15% higher than the simplified one.     

Lack of immunotoxicity of saquinavir (Ro 31-8959) used alone or in double or triple combination with AZT and ddC

Poly(ADP-ribosyl)ation is a posttranslational modification of nuclear proteins which is catalyzed by poly(ADP-ribose) polymerase and represents an immediate response of eukaryotic cells to oxidative and other types of DNA damage. Previously a strong correlation had been detected between maximal poly(ADP-ribose) polymerase activity in permeabilized mononuclear leukocytes of various mammalian species and species-specific life span. To study a possible relation between longevity and poly(ADP-ribosyl)ation in humans we measured maximal oligonucleotide-stimulated poly(ADP-ribose) polymerase activity in permeabilized, Epstein-Barr virus transformed lymphoblastoid cell lines from a French population of 49 centenarians and 51 controls aged 20-70 years. Maximal enzyme activity was significantly higher in centenarians than in controls [median of controls: 9035 cpm/10(6) cells (lower quartile: 6156; upper quartile: 11,410); median of centenarians: 10,380 cpm/10(6) cells (lower quartile: 7994; upper quartile: 12,991); P=0.031 by Mann-Whitney U test]. In a subset of 16 controls and 24 centenarians, cellular poly(ADP-ribose) polymerase content was determined by quantitative western blotting, thus allowing the calculation of specific enzyme activity. The latter was significantly higher in centenarians (P=0.006), the median value for centenarians being about 1.6-fold that of controls. Specific poly(ADP-ribose) polymerase activity was a more powerful parameter for differentiating between centenarians and controls than enzyme activity relative to cell number. In addition, in a genetic association study we analyzed 437 DNA samples (239 centenarians and 198 controls) by PCR amplification of a polymorphic dinucleotide repeat located in the promoter region of the poly(ADP-ribose) polymerase gene in an attempt to detect an association between this polymorphic marker and variability of enzyme activity or human longevity. However, this genetic analysis revealed no significant enrichment of any of the alleles or genotypes identified among centenarians or controls, but its power was limited by the relatively weak heterozygosity of this polymorphic marker in our population (51%). Viewed together with previous results on poly(ADP-ribose) polymerase activity in various mammalian species, the present data provide further evidence for the notion that longevity is associated with a high poly(ADP-ribosyl)ation capacity.     

Optical and electrical characterization of GaAs-based high-speed and high-sensitivity delta-doped resonant cavity-enhanced HMSM photodetector

We have previously reported an AlGaAs-GaAs-based delta modulation doped resonant cavity-enhanced, heterostructure metal-semiconductor-metal (HMSM) photodetector design with wavelength selectivity, high sensitivity, and high-speed properties. In this paper, the influences of the resonant cavity and the delta modulation-doped layer on the optical and electrical performances of HMSM photodetectors have been studied by using the transmission line model and Ramo's theorem, respectively. The microcavity offers narrow spectral bandwidth detection accompanied by a drastic increase of the optical field at the resonant wavelength, solving the tradeoff between high efficiency and high speed with the thinner absorption regions. The top AlGaAs delta modulation-doped layer presents an enhanced barrier height associated with the vertically oriented two-dimensional potential and field profiles rather than the horizontally oriented ones, providing very low dark current values and an increase in device responsivity and speed of the response. Optimizing the optical and electric field simultaneously results in high-performance photodetection without further scaling down the devices. Two separate groups of photodetectors with various geometries have been fabricated, characterized, and simulated: One with a delta modulation-doped structure, the other without this doped layer. Delta-doped photodetectors show wavelength selectivity at 850 nm with about a 30-nm full width at half-maximum (FWHM), 9.2 fA//spl mu/m/sup 2/ dark current, less than 30 fF capacitance, 10.6-ps FWHM, and 18.4-ps fall time. Photocurrent spectral response, dark current, time response, and capacitance-voltage measurements consistently show that the delta-doped detectors have the better optical and electrical performances over the undoped ones.     

Preparation of low-noise high-quality silicon microstrip detectors

This paper describes the various preparation phases of low-noise high-quality silicon microstrip detectors, together with the results of a test on a high-energy meson beam.