An object‐oriented interface for the dynamic memory management of sparse discrete mathematical operators in numerical scientific applications

This paper describes an object‐oriented interface for the memory management of sparse discrete mathematical operators in numerical scientific applications. The basic data structure we propose is intended to implement and cope with mathematical vectors in sparse format. This structure allows an effective implementation of more complex data structures, such as matrix and matrix‐like objects, to represent the discrete version of differential operators in numerical application codes. A research example concerning adaptive wavelet algorithms illustrates the possible applications.Copyright © 2002 John Wiley & Sons, Ltd.     

Breakdown kinetics at nanometer scale of innovative MOS devices by conductive atomic force microscopy

The breakdown (BD) kinetics of dielectrics represent a crucial issue for the reliability of microelectronics devices. In this paper, we report on an innovative and practical approach based on Conductive Atomic Force Microscopy (C-AFM) for the determination of the BD kinetics on a bare insulator surface. This technique has been applied to Pr₂O₃ films grown by Metal-Organic Chemical Vapour Deposition (MOCVD) on Si(0 0 1) and to thermally grown SiO₂ on 4H-SiC substrates. C-AFM clearly visualizes single breakdown spots under constant voltage stresses. The stress time on the C-AFM tip was varied from 1 × 10⁻³ to 1 × 10⁻¹ s. The density of BD spots, upon increasing the stress time, exhibits in both cases an exponential trend. The Weibull slope of the dielectric BD statistics has been determined by direct measurements at nanometer scale on different dielectrics having different physical thicknesses. The comparison of the Weibull slopes obtained for different dielectric thicknesses with literature data points out intrinsic and extrinsic BD events in the SiO₂/SiC system and Pr₂O₃ based layers, respectively. In the case of the SiO₂/SiC system, BD kinetics have been demonstrated to follow the percolation model, while the role of extrinsic phenomena in the BD of Pr₂O₃ films has been proved.     

Using C/X-band SAR interferometry and GNSS measurements for the Assisi landslide analysis

This work presents an analysis of the applicability of synthetic aperture radar (SAR) interferometry to landslide monitoring. This analysis was carried out by using different interferometric approaches, different spaceborne SAR data (both in the C-band and in the X-band), and in situ global navigation satellite system (GNSS) measurements. In particular, we investigated both the reliability of displacement monitoring and the issues of the cross-comparison and validation of the interferometric synthetic aperture radar (InSAR) results. The work was focused on the slow-moving landslide that affects a relevant part of the urban area of the historical town of Assisi (Italy).

A C-band ENVISAT advanced synthetic aperture radar (ENVISAT ASAR) dataset acquired between 2003 and 2010 was processed by using two different interferometric techniques, to allow cross-comparison of the obtained displacement maps. Good correspondence between the results was found, and a deeper analysis of the movement field was possible. Results were further compared to a set of GNSS measurements with a 7 year overlap with SAR data. A comparison was made for each GNSS marker with the surrounding SAR scatterers, trying to take into account local topological effects, when possible.

Further, the high-resolution X-band acquired on both ascending and descending tracks by the COSMO-SkyMed (CSK) constellation was processed. The resultant displacement fields show good agreement with C-band and GNSS measurements and a sensible increase in the density of measurements.     

Gas Chromatographic Determination of Isbufylline in Tablets for Stability Purposes

Isbufylline is a new antibronchospastic drug. A rapid and simple gas chromatographic assay of Isbufylline in tablet matrices has been developed for stability purposes. Isbufylline was extracted from tablets with ethanol containing (l,3-dimethyl-7-amil xanthine) (1 mg/ml) as the internal standard. A filtered aliquot was chromatographed with a 2% OV-17 steel column and the components were detected by a flame ionization detector. The method exhibited good linearity over the range 0.5-1.5 mg/ml (r=0.9997). Mean recovery of isbufylline added to tablet excipients was 99.07%. Mean assay results for 10 and 80 mg tablets were 95.72% and 96.73%, respectively. No degradation was detected during accelerated stability studies at elevated temperatures, confirming the excellent stability of this drug in tablets.     

Potential Effect of CD271 on Human Mesenchymal Stromal Cell Proliferation and Differentiation

The Low-Affinity Nerve Growth Factor Receptor (LNGFR), also known as CD271, is a member of the tumor necrosis factor receptor superfamily. The CD271 cell surface marker defines a subset of multipotential mesenchymal stromal cells and may be used to isolate and enrich cells derived from bone marrow aspirate. In this study, we compare the proliferative and differentiation potentials of CD271⁺ and CD271⁻ mesenchymal stromal cells. Mesenchymal stromal cells were isolated from bone marrow aspirate and adipose tissue by plastic adherence and positive selection. The proliferation and differentiation potentials of CD271⁺ and CD271⁻ mesenchymal stromal cells were assessed by inducing osteogenic, adipogenic and chondrogenic in vitro differentiation. Compared to CD271⁺, CD271⁻ mesenchymal stromal cells showed a lower proliferation rate and a decreased ability to give rise to osteocytes, adipocytes and chondrocytes. Furthermore, we observed that CD271⁺ mesenchymal stromal cells isolated from adipose tissue displayed a higher efficiency of proliferation and trilineage differentiation compared to CD271⁺ mesenchymal stromal cells isolated from bone marrow samples, although the CD271 expression levels were comparable. In conclusion, these data show that both the presence of CD271 antigen and the source of mesenchymal stromal cells represent important factors in determining the ability of the cells to proliferate and differentiate.     

Analysis of PCR-based methods for characterization of Listeria monocytogenes strains isolated from different sources

Listeria monocytogenes strains, isolated from various sources (food, environment, and animals), were used to test different PCR-based methods to investigate their capability to define the strain origin. RAPD-PCR with three primers and the SAU-PCR method, in which the DNA was first digested with the Sau3A restriction endonuclease and then amplified with a primer designed on the restriction site, were carried out, and the profiles obtained were used to perform cluster analysis. Based on the cluster analysis of Listeria spp. strains, obtained from international collections, the coefficient of similarity was selected. The results obtained showed that the methods tested in the study gave different levels of differentiation between the strains tested. The RAPD protocol using the P1254 primer and the SAU-PCR gave appreciable results only for strains isolated from animals and from a food processing plant in two different periods of the year 2003. Better differentiation was observed using the RAPD-PCR with primer D8635. As a matter of fact, it was able to distinguish L. monocytogenes obtained from different species of animals, different food samples and strains from the same production plant isolated in different periods of the year. Also primer M13 gave positive results, but the coefficient of similarity to use had to be increased to 80%. On the basis of the results observed, RAPD-PCR with primers D8635 and M13 should be considered reliable tools for epidemiological investigations focusing on L. monocytogenes.     

In vitro fermentation characteristics of diets with different forage/concentrate ratios: comparison of rumen and faecal inocula

BACKGROUND: The aim of this trial was to evaluate the replacement of rumen fluid with faeces as inoculum in studying the in vitro fermentation characteristics of diets for ruminants using the in vitro gas production technique. Six iso‐protein diets with different forage/concentrate ratios were incubated with rumen fluid (RI) or faeces (FI) collected from sheep. RESULTS: Most of the fermentation parameters were influenced by diet and inoculum (P < 0.01). With both inocula, organic matter degradability (dOM), cumulative gas production (OMCV) and maximum fermentation rate (R_max) increased as the amount of concentrate in the diet increased. R_max was lower with FI vs RI (P < 0.01); dOM was higher with FI vs RI and the diet × inoculum interaction was significant. As expected, with both inocula, R_max increased as the neutral detergent fibre content of the diet decreased. Significant correlations were obtained using both inocula between OMCV/dOM and gas/volatile fatty acid (VFA), while the correlation VFA/dOM was significant only with FI. The microbial biomass yield calculated by stoichiometric analysis for all diets was higher with FI vs RI. With FI the organic matter used for microbial growth showed an overall decreasing trend as the amount of concentrate in the diet increased. CONCLUSION: The results indicate that both faeces and rumen fluid from sheep have the potential to be used as inoculum for the in vitro gas production technique. Copyright © 2011 Society of Chemical Industry     

Evolution of 5-(hydroxymethyl)furfural and furfural in the production chain of the aged vinegar Aceto Balsamico Tradizionale di Modena

The present investigation focuses on the monitoring of furfurals along the production chain of the aged vinegar Aceto Balsamico Tradizionale di Modena, from the starting raw material to the final product, in order to control the quality and safety of this food. In particular, the aim of the study is to achieve a reduction in the furfurals content and, therefore, an optimised heating procedure for the starting grape juice was proposed and compared to that which is currently adopted. 5-(Hydroxymethyl)furfural (HMF) and furfural were determined by HPLC. Results show that the suggested heating procedure leads to a decrease of furfurals in the cooked must. In addition, for comparison purposes, HMF and furfural were also measured during the ageing phase of the vinegar and in the final marketable products as well.