Temporal and spatial trends of perfluorinated compounds in ringed seal (Phoca hispida) from Greenland

Perfluorinated compounds (PFCs), such as perfluorooctane sulfonate (PFOS) and related compounds, have been identified as global pollutants and have shown their bioaccumulation into higher trophic levels in the food chain. PFCs have been found in remote areas far from sources, such as the Arctic. In this study spatial and temporal trends in the concentrations of selected PFCs were measured using archived liver samples of ringed seal (Phoca hispida) from East and West Greenland. The samples were collected in four different years at each location, between 1986 and 2003 in East Greenland and between 1982 and 2003 in West Greenland. PFOS was the major contributor to the burden of PFCs in samples, followed by perfluoroundecanoic acid (PFUnA). Perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA) were also detected in most samples. Perfluorohexane sulfonate (PFHxS) and perfluorooctane sulfonamide (PFOSA) were only found sporadically. Perfluorooctanoic acid was not found in detectable concentrations in any sample. Regression analysis of logarithmic transformed PFOS, PFDA, and PFUnA median concentrations indicated a significant temporal trend with increasing concentrations at both locations. A spatial trend in PFOS concentrations (ANOVA, p < 0.0001) was observed between the two sampling locations, with significantly higher concentrations in seals from East Greenland.     

PiecewiseC 1-shape-preserving Hermite interpolation

A local scheme for piecewiseC ¹-Hermite interpolation is presented. The interpolant is obtained patching together cubic with quadratic polynomial segments; it is co-monotone and/or co-convex with the data. Under appropriate assumptions the method is fourth-order accurate.     

Magnetic-shield-type fault current limiter equivalent circuit

In order to investigate how a superconducting fault current limiter (SFCL) can enhance the performance of a power system, an accurate circuit model of the device needs to be introduced in power system simulators. In this paper, we present a finite-element numerical model to calculate the time evolution of the voltage across a magnetic-shield-type SFCL, when it is connected to an external circuit. The calculation of the voltage is carried out by using the energy conservation law, and requires the calculation, at any instant, of the current density distribution inside the superconducting tube and magnetization distribution inside the ferromagnetic core of the device. These distributions are determined by means of two coupled equivalent electric and magnetic circuits, whose topology and components are obtained through the spatial integration of quasi-static form of Maxwell equations. Comparisons between numerical and experimental results are shown.     

The electronic configuration and the conductance of silicon nanograins: An application of the scattering approach

The purpose of this study is the assessment of the properties of the electronic structure and of the transport characteristics of silicon nanostructures of a size comparable with the experimental ones. Accordingly, crystalline columnar grains, sandwiched between two adsorbing aluminum contacts, with a size of several hundreds atoms and linear dimensions up to a few nanometers, have been considered. The calculation method elaborates on the scattering approach, as reported in the recent chemical literature, using the extended Hückel theory for the evaluation of either the electronic charge or the transmission function. The calculations show that the binding energy has bulk-like features, i.e. its size dependence has a nearly flat asymptote with a value close to the cohesive energy of the solid. However the effect of the loosely coordinated boundary atoms is perceptible even at the sizes few hundreds atoms and produces an oscillatory behaviour of the binding energy. The comparison between this energy and the conductance indicates that both quantities increase at the same sizes and therefore the orbitals of the loosely bounded atoms are the important conductive channels.     

A ?P-Controlled Sliding Integrating-Type Differentiator for Biomedical Signal Processing: Application to dc Ocular Rheography

This paper describes a measurement technique for precise evaluation of hematic ocular flow. The main characteristics and advantages of the proposed technique over conventional approaches are first pointed out. Next, the design criteria and the performance achievable with the prototype instrument developed to carry out the measurement completely automatically, are examined in detail. The instrument, thanks to its microprocessor-based implementation, allows a certain degree of tailoring of the measurement in accordance with the patient's peculiarities. Moreover, it provides the possibility of monitoring the ocular arterial inflow during the test, thus guaranteeing that safety limits will not be exceeded.     

Taxonomies and correlates of physique.

"Subjective" and "objective" taxonomies of human physique are more or less correlated among themselves and in different degrees with an array of nonanthropometric variables of interest to psychologists. There is probably closer corespondence between anthropometric data and function than is reported in the literature. The most advanced taxonomies can be improved, principally by: greater differentiation of predictive anatomical variables; increasing the scope of the systems to include such elements as internal body organs, the differential influences of nutrition, and age; and through use of refined multivariate statistical techniques for representing and analyzing complex data. (3-p. ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Field-enhanced carrier generation in MOS capacitors

When sufficiently high voltage steps are used for driving a metal-oxide-semiconductor capacitor (MOSC) towards deep inversion, the temporal evolution of the current and of the high-frequency capacitance during the return to equilibrium cannot be interpreted on the basis of a theory assuming a constant bulk generation lifetime. A more general theory, which takes into account field-dependent carrier emission rates, is developed and it is shown how current and h.f. capacitance measurements can be used to determine the field dependence of the bulk generation lifetime. The results of experiments performed on differently processed MOSC's are presented; they support the hypothesis that field-enhancement of carrier emission rates takes place according to a mechanism of the Poole-Frenkel-type.     

Molecular typing of Staphylococcus aureus isolated from Italian dairy products on the basis of coagulase gene polymorphism, multiple-locus variable-number tandem-repeat and toxin genes

Coagulase gene restriction fragment length polymorphism (RFLP), six-locus variable-number tandem-repeat analysis patterns (MLVA) and detection of enterotoxin genes (se) (sea, sec, sed, seg, seh, sei, sej and sel) were used to determine the phylogenetic relationship among isolates of Staphylococcus aureus isolated from dairy products from different regions of Italy. A total of 25 Staph. aureus were subtyped into 16 coagulase genotypes by RFLP, and MLVA revealed marked genomic variability. Furthermore, 17 of the isolates harboured at least one toxin gene, with the predominance of sea, sed and sej among cow isolates and sec-sel among the goat and sheep strains. Combined RFLP, MLVA polymorphism and se genes were found to be useful techniques for discriminating several genetic variants in Staph. aureus isolates.