A GC-EI-MS/MS Method for the Determination of 15 Polybrominated Diphenyl Ethers (PBDEs) in Fish and Shellfish Tissues

This paper describes the development and validation of an analytical method to determine 15 polybrominated diphenyl ethers (PBDEs) in fish and shellfish tissues with gas chromatography coupled to triple quadrupole mass spectrometry using electron impact source (GC-EI-MS/MS). A QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe)-like procedure was applied; the extract was cleaned up on an acidic Extrelut-NT3 column connected on top of a silica cartridge and further purified with gel permeation chromatography (GPC). The SIM acquisition proved to yield better results than traditional MRM approach for octa-, nona-, and deca-brominated congeners. The validation study was carried out in inter-laboratory conditions. The average recoveries were in the range 66–118%, with relative standard deviations generally lower than or equal to 22%. Quality assurance and quality control practices were thoroughly described and highlighted. These long and tedious practices are fundamental to obtain reliable quantitative data during food monitoring programs and, therefore, to support daily intake assessments. Finally, the procedure was applied to the analysis of marine fish samples collected in local markets. Mackerel and mullet were the most contaminated species.     

Fingerprint Clustering with Bounded Number of Missing Values

The problem of clustering fingerprint vectors with missing values is an interesting problem in Computational Biology that has been proposed in Figueroa et al. (J. Comput. Biol. 11(5):887–901, 2004). In this paper we show some improvements in closing the gaps between the known lower bounds and upper bounds on the approximability of variants of the biological problem. Moreover, we have studied two additional variants of the original problem proposed in Figueroa et al. (Proc. 11th Computing: The Australasian Theory Symposium (CATS), CRPIT, vol. 41, pp. 57–60, 2005). We prove that all such problems are APX-hard even when each fingerprint contains only two unknown positions and we present a greedy algorithm that has constant approximation factors for these variants. Despite the hardness of these restricted versions of the problem, we show that the general clustering problem on an unbounded number of missing values such that they occur for every fixed position of an input vector in at most one fingerprint is polynomial time solvable.     

Relationship Between Chemical Markers and Sensory Score of Traditional Balsamic Vinegars Using a Screening Approach Combined with Rapid Assessment Methods

In this study, 200 samples of traditional balsamic vinegar (TBV) of Reggio-Emilia, a typical Italian “aged dressing” with Protected Denomination of Origin, were analyzed to model the relationship between sensory scores with some pre-selected compounds/parameters, such as Brix value, water activity (a _w), titratable acidity, color, polymeric compounds, and electronic nose signal. Statistical techniques, such as nonlinear regression and Principal Component Analysis (PCA) were used to model the relationship among vinegars composition. The sensory score of panelists was mainly correlated with Brix (r?=?0.85) followed by brown color at 445 nm (r?=?0.74) and water activity (a _w) (r?=??0.79), whereas the polymeric compounds content showed a negative correlation with water activity (r?=?–0.73). In particular, the water activity of TBVs at different Brix values followed a nonlinear trend with good fitting (r?=?0.857) with K?=?3.10 that was consistent with the value reported in the literature for fructose and glucose. Electronic nose (enose) data from TBVs and six marker compounds (acetic acid, butyric acid, vanillin, ethyl-phenylacetate, phenylethyl alcohol, and furfural) combined with PCA revealed a pattern related to the ageing of TBVs.     

Optical properties of high-density dispersions of particles: application to intralipid solutions

We propose to study the scattering properties of dense distributions of spherical scatterers by resorting to an iterative solution of the Foldy-Twersky equation for the propagation of the coherent field. As a result of the first step of the iterative procedure, the host medium is substituted by an effective medium of complex refractive index to account for the multiple-scattering processes that occur among the particles. Although we truncate the above-mentioned iterative procedure to the second step, the results of our calculations are in excellent agreement with previous experimental results of Zaccanti et al. ("Measurement of optical properties of high-density media," to be published in Applied Optics) for the scattering coefficient of Intralipid solutions up to a volume density of 15% and show a limited disagreement at a volume density of 22%.     

Bio-inspired solutions for locomotion in the gastrointestinal tract: background and perspectives

This paper illustrates a bio-inspired approach to effective, smooth and safe navigation in the human body and, in particular, in the gastrointestinal tract. This idea originates from the medical need to develop more powerful tools for microendoscopy, which is one of the most challenging frontiers of modern medicine. Understanding motion and perception systems of lower animal forms, such as parasites, worms, insects and snakes, can help to design and fabricate bio-inspired robots able to navigate in tortuous, slippery and difficult-to-access cavities of the human body. A preliminary study of a biomimetic adhesion system for the human tissues is presented in this work and some technological implementations are illustrated and discussed. Finally, some issues concerning the goals of smart and reactive locomotion are considered and the most promising and relevant enabling technologies are discussed.     

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.     

Usage of SoS methodologies in production system design

Production systems design is a multifaceted task, due to a variety of aspects such as the mutual interdependency between the sub-systems, the variety of configurations and alternative system control strategies, the multiple managerial and “soft” aspects that cast an influence on the behavior of the system. A reasonable number of modeling tools can be applied to production system design, but they tend to divide the problem into unconnected sub-problems whose individual solutions may result in a poor global one. This is despite the fact that production design encompasses all aspects of manufacturing operations, and needs a systemic approach, as clearly shown in practitioner-oriented literature. This paper proposes to apply the “System of Systems” approach to production system design in order to represent their main aspects and support the rational definition of the path leading from corporate strategy to system (re)design.     

Characterization of soil deformation due to blast-induced liquefaction by UAV-based photogrammetry and terrestrial laser scanning

ABSTRACT

Soil liquefaction due to an earthquake can lead to permanent soil deformation and reduction of load-bearing capacity that in turn could act on building stability. Since a quantitative evaluation of post-liquefaction settlements is often very difficult, field scale liquefaction tests, carried out under controlled conditions, such as blast tests, are used to perform a correct quantitative analysis of the liquefaction phenomena. Among the significant parameters related to a blast test, there are the geometric ones, i.e. the extension of the area affected by the blast-induced liquefaction and the corresponding vertical displacements. This article shows the results of a blast test carried out at a trial site located in Mirabello (Ferrara, Italy) from a remote-sensing perspective. Data provided by aerial Structure-from-Motion photogrammetry, supported by terrestrial laser scanning measurements, were used to evaluate the soil deformation that, in the specific case study, aided a geological/geotechnical interpretation of the blast test results. In general, the proposed method can be used to characterize areas affected by blast-induced liquefaction, including those cases where blasting is used as ground improvement technique aimed at mitigating the seismic hazard.     

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.