A methodology for verification of digital items in fair exchange protocols with active trustee

Fair exchange constitutes a fundamental mechanism for electronic commerce. Fair exchange assumes that it is possible to verify the correctness of the digital items to be exchanged. However, when an item is indescribable , i.e., it cannot be formally specified, its verification becomes difficult, if not impossible. This hinders a practical deployment of fair exchange. We propose a methodology for the verification of indescribable digital items. The methodology allows a participant in a fair exchange protocol to personally verify the indescribable item without giving him any practical advantage over the other participant, and therefore without violating the fairness imposed by the protocol.     

Towards quantifying tropical tree species richness in tropical forests

This letter reports tests of whether the normalized difference vegetation index (NDVI) from Landsat Enhanced Thematic Mapper Plus (ETM+) and radar backscatter (C‐, L‐ and P‐bands) from Airborne Synthetic Aperture Radar (AIRSAR) imagery can be used to estimate tree species richness from 25 1‐ha plots within continuous lowland forest types (dry, moist, wet) in the Panama Canal Zone Watershed. Species richness for trees ranged from 49 to 98 species per ha. There was no evidence that density, basal area, above‐ground biomass or P‐backscatter was correlated with tree species richness. Mean and standard deviations (SDs) of the NDVI could explain 39% and 37% of the variance in tree species richness, respectively (41% when combined), while mean radar backscatter in the shorter wavelength C‐ and L‐bands could explain 44% and 33% of the variance in tree species richness, respectively (50% when combined).     

Enabling Human–Machine Interaction in Projected Virtual Environments Through Camera Tracking of Imperceptible Markers

Existing tracking methods designed for interacting with projection-based displays generally require visible artifacts to be introduced in the environment in order to guarantee effective stability and accuracy. For instance, in optical-oriented approaches, either the camera sensor or the reference pattern used for tracking are often located within the user's sight (or interfere with it), thus occluding portions of the scene or altering the perception of the virtual environment. Several ways to tackle these issues have been recently explored. Proposed approaches basically aim at making the presence of tracking references in the virtual space transparent to the user. However, such solutions introduce possibly critical constraints on required hardware or environment configuration. In this work, a novel tracking approach based on imperceptible fiducial markers is proposed. The approach relies on a hiding technique that allows digital images to be embedded in (and retrieved from) a projected scene by exploiting the properties of light polarization and additive color mixing. In particular, the virtual scene is obtained by overlapping the light beams of two projectors and by dealing with markers’ hiding via color compensation. A prototype setup has been deployed, where interaction with a flat surface projection environment has been evaluated in terms of tracking accuracy and artifacts avoidance performance by using a consumer camera equipped with a polarizing filter. Although the performed tests presented in this article represent only a preliminary and a partial evaluation of the proposed approach, they provided encouraging results indicating that the proposed technique could be possibly applied in more complex interaction scenarios still with limited hardware requirements.     

Mycotoxin occurrence in beer produced in several European countries

The occurrence of ochratoxin A, trichothecenes, fumonisins and aflatoxins in a sample of 106 beers produced in several European countries, was investigated. The analyses were conducted using high-performance liquid chromatography with fluorimetric detection for ochratoxin A and aflatoxins, gas-chromatography and high-performance liquid chromatography, both coupled with mass spectrometer, for trichothecenes and fumonisins, respectively. Aflatoxins were not detected in any samples, whereas ochratoxin A, deoxynivalenol and fumonisins were found in a relatively high number of samples. Their presence was at low levels in all samples; however, some differences were observed between the European countries. As regards ochratoxin A, beer samples from southern Europe showed levels always lower than 0.040 μg l^?1, while the samples from other European countries showed significantly higher values, up to 0.189 μg l^?1 (P < 0.001). For fumonisins, the levels of Italian beers were significantly higher compared to the samples from other countries (P = 0.006).     

New Strong MM FIR Emissions in CH2=CF2 Pumped by a Pulsed CO2 Laser

By pumping with a suitable pulsed CO₂ laser we have produced several strong MM laser lines in 1,1 difluoroethene. All the emissions are easily identified because the emission spectroscopy is simplified in pulsed optical pumping.     

Synthesis of thermoreactive polysiloxanes with cyclic fragments in the side chain

The synthesis of polysiloxanes with pendant unsaturated cyclic fragments have been successfully performed by hydrosilylation reactions of polymethylhydrosiloxane with 4‐vinyl‐1‐cyclohexene in the presence of platinum hydrochloric acid (0.1 M solution in THF), Karstedt's catalyst (Pt₂[(VinSiMe₂)₂O]₃) and platinum on the charcoal (5%). Reactions were carried out at various temperatures with different ratios of initial compounds. It was shown, that not all active ≡Si? H groups take part in the hydrosilylation reaction. Some kinetic parameters of reactions were studied. The synthesized oligomers were characterized by FTIR, ¹H, ¹³C, H,H‐COSY, and C,H‐correlation NMR spectroscopy. Calculations using the quantum‐chemical semi empirical AM1 method for modeling reactions between methyldimethoxysilane [Me(MeO)₂SiH] and 4‐vinyl‐1‐cyclohexene were performed to evaluate possible reaction paths. Synthesized oligomers were characterized by gel‐permeation chromatography, differential scanning calorimetric, thermogravimetric, and wide‐angle X‐ray analyses. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Influence of the structure in low-Pt loading electrodes for polymer electrolyte fuel cells

The influence of the structure and composition of the electrodes on a polymer electrolyte fuel cell (PEFC) performance has been investigated. Electrodes have been prepared by varying the composition of diffusion and/or catalyst layer. Improvements have been obtained by introducing a hydrophobic carbon layer between the carbon paper and the catalyst layer for the gas diffusion backing. High performance has been achieved with low Pt-loading electrodes (0.15 mg/cm²) by including the ionomer Nafion in the catalyst ink. Electrodes have been characterized by SEM-EDX analyses and electrochemical tests in a 50 cm² single cell.     

Identification of concrete fracture parameters through size effect experiments

This paper deals with the identification of concrete fracture parameters through indirect methods based on size effect experiments. These methods utilize the size effect curve (structural strength versus structural size), associated with a certain specimen geometry, to identify the tensile strength and the initial fracture energy. These two parameters, in turn, are typically used to characterize the peak and the initial post-peak slope of the cohesive crack law. In the literature, two different approaches can be found for the calculation of the size effect curve: (a) an approach based on the polynomial interpolation of numerically calculated structural strengths of geometrically similar specimens of different sizes, and (b) the classical approach based on equivalent elastic fracture mechanics, which gives rise to the well-known Bažant’s size effect law (SEL). In this paper, the two approaches are first reviewed, the relationship between them is investigated, and a new procedure to identify the tensile strength using the SEL is proposed. Then several sets of experimental results, recently performed at the Politecnico di Milano, are analyzed with both approaches in order to assess their range of applicability and accuracy in the identification of the two fracture parameters specified above.     

Evaluation of gamma rays influence on some biochemical and microbiological aspects in black truffles

The effects of two gamma-ray doses (1.5 kGy and 2.0 kGy) on some biochemical aspects and on the microbiological profile of black truffles was monitored, immediately after treatment and after 30 days of storage at 4 °C. Electrophoretic and chromatographic analyses of proteins and peptides, just like monitoring of polyphenol content, peroxides formation and microbial profile, allowed for the first time a better understanding of the mechanisms responsible for biochemical alterations and bacterial pattern in black truffles during their storage. Treatment at 1.5 kGy appeared to better preserve the characteristics of the fresh product. In 2.0 kGy-samples, the protein profile was characterised by a 20 kDa-polypeptide, which could be considered as an useful marker of the irradiation treatment and of the storage time of the product. MALDI-TOF mass spectrometry analysis did not permit a correct identification from tryptic peptides in databases, although the nano-ES/MS/MS analyses performed on the 10 kDa tryptic digest peptides showed an amino acidic sequence entirely contained in a protein of filamentous fungus Neurospora crassa.