A chip removal facility for indium bump bonded pixel detectors

Yield maximization in multichip hybrid pixel sensors is a crucial issue in large volume productions planned for future High-Energy Physics experiments. Bump bonding process optimization can guarantee statistical single bump failure rates at the acceptable level of 10–100 ppm; nevertheless, systematic effects connected to process repeatability can affect the functionality of a full chip in a module to a much larger extent. Because of this, the reversibility of the bonding procedure has been investigated. A feasibility study on single chip assemblies for the ATLAS experiment has been successfully completed, proving the possibility of reworking. As a result of it, a dedicated facility has been conceptually designed, engineered and commissioned. The characteristics of the facility in terms of motion, temperature and tensile strength control are outlined, together with the main results.     

Leaf level detection of solar induced chlorophyll fluorescence by means of a subnanometer resolution spectroradiometer

A leaf level investigation on the spectral signature of Phaseolus vulgaris was undertaken by using a very high spectral resolution spectroradiometer featuring full width at half maximum of 0.06 nm and spectral range of 635.5-802.5 nm. High spectral resolution allows detection of leaf reflected and emitted radiance fields in two narrow absorption bands at 687 and 760 nm, respectively, where solar irradiance is strongly reduced owing to molecular oxygen absorption of the terrestrial atmosphere. The flux emitted due to chlorophyll fluorescence was measured using the Fraunhofer line depth principle by spectrally modelling the signal, capitalizing on the high resolution of the spectroradiometer devices. An experiment was conducted on two potted bean plants. One was maintained in good health for use as a reference while the other was treated with a photosystem II inhibitor. Collected spectra show that the fluorescence emission produces a pair of characteristic peaks superimposed on the typical leaf-specific reflectance curve. The magnitude of the fluorescence signal of the herbicide-treated leaf was four times greater than that of the control plant, thus indicating damage to the photosynthetic apparatus of the plant.     

Improved version of a silicon telescope system for measurements of charged multiplicity variations

The paper describes an improved version of a system of two telescopes of silicon detectors for the measurement of charged multiplicity variations. The system is used to detect charm and beauty decays in the WA71 experiment at CERN. Characteristics and performance of the system and of the related electronic readout are described.     

Role of antioxidants and intracellular free radicals in retinamide-induced cell death

The cancer chemopreventive synthetic retinoid N-(4-hydroxyphenyl)retinamide (HPR) possesses antiproliferative and apoptotic activity at pharmacological doses. In this study we show that addition of antioxidants to HL-60 cells cultured in the presence of 3 microM HPR, markedly suppresses the apoptopic effect of the retinoid and significantly prolongs cell survival (48-96 h). We also show, by the use of the oxidation-sensitive probe 2',7'-dichlorofluorescin diacetate (DCF-DA) and in combination with flow cytometric and spectrofluorimetric analysis, that treatment of cells with 3 microM HPR results in an immediate and sustained production of intracellular free radicals, most likely hydroperoxides. Interestingly, the formation of these HPR-induced free radicals is effectively blocked by the water soluble antioxidants L-ascorbic acid and N-acetyl-L-cysteine. Neither 3-15 microM N-(4-methoxyphenyl) retinamide (MPR), the structurally similar but biologically inert analog of HPR, nor 3 microM doses of the retinoids all-trans retinoic acid, 9-cis-retinoic acid, TTNPB and SR11237 induce intracellular free radicals, thus indicating that the specificity of this phenomenon is restricted to HPR. Altogether, we provide the first direct evidence that HPR stimulates the generation of intracellular free radicals, which appear to have a causative role in the induction of apoptosis in vitro. Our findings raise the possibility that the therapeutic efficacy of HPR may, at least in part, depend on these apoptosis-inducing oxidative phenomena.     

Comparative mapping of Xp22 genes in hominoids--evolutionary linear instability of their Y homologues

The extracellular matrix is now recognized as a biologically active and dynamic composition of structural, adhesive, and counteradhesive fibrous proteins embedded in a hydrated ground substance of glycosaminoglycans and proteoglycans. The ability of resident cells to detect small differences in the specific combination, concentration and distribution of matrix components suggests that perturbation of the homeostatic matrix can lead to remodelling following angioplasty. Recent studies reviewed herein have focused on how alterations of the relative composition of matrix components ultimately leads to changes in cell growth, behaviour and differentiation, all of which can significantly contribute to remodelling of the vascular wall following injury. These cell-matrix interactions may provide novel therapeutic targets in the prevention of unfavourable remodelling that leads to restenosis.     

Combining medium and coarse spatial resolution satellite data to improve the estimation of sub-pixel NDVI time series

The potential of multitemporal coarse spatial resolution remotely sensed images for vegetation monitoring is reduced in fragmented landscapes, where most of the pixels are composed of a mixture of different surfaces. Several approaches have been proposed for the estimation of reflectance or NDVI values of the different land-cover classes included in a low resolution mixed pixel. In this paper, we propose a novel approach for the estimation of sub-pixel NDVI values from multitemporal coarse resolution satellite data. Sub-pixel NDVIs for the different land-cover classes are calculated by solving a weighted linear system of equations for each pixel of a coarse resolution image, exploiting information about within-pixel fractional cover derived from a high resolution land-use map. The weights assigned to the different pixels of the image for the estimation of sub-pixel NDVIs of a target pixel i are calculated taking into account both the spatial distance between each pixel and the target and their spectral dissimilarity estimated on medium-resolution remote-sensing images acquired in different periods of the year. The algorithm was applied to daily and 16-day composite MODIS NDVI images, using Landsat-5 TM images for calculation of weights and accuracy evaluation.Results showed that application of the algorithm provided good estimates of sub-pixel NDVIs even for poorly represented land-cover classes (i.e., with a low total cover in the test area). No significant accuracy differences were found between results obtained on daily and composite MODIS images. The main advantage of the proposed technique with respect to others is that the inclusion of the spectral term in weight calculation allows an accurate estimate of sub-pixel NDVI time series even for land-cover classes characterized by large and rapid spatial variations in their spectral properties.