Uptake of dimercaptosuccinate-coated magnetic iron oxide nanoparticles by cultured brain astrocytes

Magnetic iron oxide nanoparticles (Fe-NP) are currently considered for various diagnostic and therapeutic applications in the brain. However, little is known on the accumulation and biocompatibility of such particles in brain cells. We have synthesized and characterized dimercaptosuccinic acid (DMSA) coated Fe-NP and have investigated their uptake by cultured brain astrocytes. DMSA-coated Fe-NP that were dispersed in physiological medium had an average hydrodynamic diameter of about 60 nm. Incubation of cultured astrocytes with these Fe-NP caused a time- and concentration-dependent accumulation of cellular iron, but did not lead within 6 h to any cell toxicity. After 4 h of incubation with 100-4000 μM iron supplied as Fe-NP, the cellular iron content reached levels between 200 and 2000 nmol mg?1 protein. The cellular iron content after exposure of astrocytes to Fe-NP at 4?°C was drastically lowered compared to cells that had been incubated at 37?°C. Electron microscopy revealed the presence of Fe-NP-containing vesicles in cells that were incubated with Fe-NP at 37?°C, but not in cells exposed to the nanoparticles at 4?°C. These data demonstrate that cultured astrocytes efficiently take up DMSA-coated Fe-NP in a process that appears to be saturable and strongly depends on the incubation temperature.     

Size Effect of Insulating Nano-Inclusions in Y�CBa�CCu�CO Bulk Superconductors Fabricated by Seeded Infiltration Growth

We have conducted an experimental study on the effect of the pinning centers size on the superconducting properties in textured YBCO samples. In this work, we investigated the effectiveness of the addition of an insulating inclusion on the superconducting and magnetic properties of textured YBCO bulk materials. The purpose of this study was to ascertain whether the size of artificial pinning centers is able to affect the superconducting properties of our samples. To this effect insulating nano-pinning centers with two different particle size distributions of about 20 nm and 130 nm have been successfully incorporated within YBCO matrix by slight doping with nano-particle alumina dispersions. The microstructure and superconducting properties were investigated by scanning electron microscopy (SEM) and SQUID. The results indicate that slight inclusions of nano-alumina can enhance the flux-pinning capability of samples. This study underlines the dependence of the pinning force on the size of the pinning centers.     

Food science challenge: translating the dietary guidelines for Americans to bring about real behavior change

Food scientists and nutrition scientists (dietitians and nutrition communicators) are tasked with creating strategies to more closely align the American food supply and the public's diet with the Dietary Guidelines for Americans (DGA). This paper is the result of 2 expert dialogues to address this mandate, which were held in Chicago, Illinois, and Washington, D.C., in early October 2010 between these 2 key scientific audiences. It is an objective that has largely eluded public health experts over the past several decades. This document takes the perspective of food scientists who are tasked with making positive modifications to the food supply, both in innovating and reformulating food products, to respond to both the DGA recommendations, and to consumer desires, needs, and choices. The paper is one of two to emerge from those October 2010 discussions; the other article focuses on the work of dietitians and nutrition communicators in effecting positive dietary change.     

Identifying vulnerable populations through an examination of the association between multipollutant profiles and poverty

Recently, concerns have centered on how to expand knowledge on the limited science related to the cumulative impact of multiple air pollution exposures and the potential vulnerability of poor communities to their toxic effects. The highly intercorrelated nature of exposures makes application of standard regression-based methods to these questions problematic due to well-known issues related to multicollinearity. Our paper addresses these problems by using, as its basic unit of inference, a profile consisting of a pattern of exposure values. These profiles are grouped into clusters and associated with a deprivation outcome. Specifically, we examine how profiles of NO(2)-, PM(2.5)-, and diesel- (road and off-road) based exposures are associated with the number of individuals living under poverty in census tracts (CT's) in Los Angeles County. Results indicate that higher levels of pollutants are generally associated with higher poverty counts, though the association is complex and nonlinear. Our approach is set in the Bayesian framework, and as such the entire model can be fit as a unit using modern Bayesian multilevel modeling techniques via the freely available WinBUGS software package, (1) though we have used custom-written C++ code (validated with WinBUGS) to improve computational speed. The modeling approach proposed thus goes beyond single-pollutant models in that it allows us to determine the association between entire multipollutant profiles of exposures with poverty levels in small geographic areas in Los Angeles County.     

Reconstructing directed signed gene regulatory network from microarray data

Great efforts have been made to develop both algorithms that reconstruct gene regulatory networks and systems that simulate gene networks and expression data, for the purpose of benchmarking network reconstruction algorithms. An interesting observation is that although many simulation systems chose to use Hill kinetics to generate data, none of the reconstruction algorithms were developed based on the Hill kinetics. One possible explanation is that, in Hill kinetics, activation and inhibition interactions take different mathematical forms, which brings additional combinatorial complexity into the reconstruction problem. We propose a new model that qualitatively behaves similar to the Hill kinetics, but has the same mathematical form for both activation and inhibition. We developed an algorithm to reconstruct gene networks based on this new model. Simulation results suggested a novel biological hypothesis that in gene knockout experiments, repressing protein synthesis to a certain extent may lead to better expression data and higher network reconstruction accuracy.     

WAW Location-based Service Positioning

Coordinated positioning operations require the user to be aware, not only, of his own position but also of the positions of the other elements on his team. Its deployment can be supported in WAW (??Where Are We???) location-based services, where the position of each user is made available to the rest of the group. This paper presents a method for the estimation of a user??s position based on measurements from a group of Global Positioning System (GPS) receivers. None of the GPS receiver positions, used in the estimation process, is considered to be known. The proposed approach leads to an improvement on the accuracy of the position estimates, when compared with those computed on an autonomous way, and has a direct application in the development of enhanced services in WAW location-based services. The positioning estimator takes advantage from the fact that, in this type of location-based service, GPS measurements are available from several receivers. Instead of estimating the user??s position based only on the measurements of his own GPS receiver, the proposed approach uses the measurements from all the GPS receivers in the group. The paper presents details of the positioning model and estimator used to achieve the accuracy improvements. Simulation results are presented based on real GPS satellite ephemeris, collected at the University campus.     

Wavelet shrinkage: unification of basic thresholding functions and thresholds

This work addresses the unification of some basic functions and thresholds used in non-parametric estimation of signals by shrinkage in the wavelet domain. The soft and hard thresholding functions are presented as degenerate smooth sigmoid-based shrinkage functions. The shrinkage achieved by this new family of sigmoid-based functions is then shown to be equivalent to a regularization of wavelet coefficients associated with a class of penalty functions. Some sigmoid-based penalty functions are calculated, and their properties are discussed. The unification also concerns the universal and the minimax thresholds used to calibrate standard soft and hard thresholding functions: these thresholds pertain to a wide class of thresholds, called the detection thresholds. These thresholds depend on two parameters describing the sparsity degree for the wavelet representation of a signal. It is also shown that the non-degenerate sigmoid shrinkage adjusted with the new detection thresholds is as performant as the best up-to-date parametric and computationally expensive method. This justifies the relevance of sigmoid shrinkage for noise reduction in large databases or large size images.     

Recent Upgrades and Extensions of the ASDEX Upgrade ECRH System

The multi-frequency Electron Cyclotron Heating (ECRH) system at the ASDEX Upgrade tokamak employs depressed collector gyrotrons, step-tunable in the range 105?C140 GHz. The system is equipped with a fast steerable launcher allowing for remote steering of the ECRH RF beam during the plasma discharge. The gyrotrons and the mirrors are fully integrated in the discharge control system. The polarization can be controlled in a feed-forward mode. 3 Sniffer probes for millimeter wave stray radiation detection have been installed.     

Dietary fibres in pulse seeds and fractions: Characterization,functional attributes,and applications

Pulses are a good source of dietary fibre and other important nutrients. Flours and fibre-rich fractions obtained from pulse crops can be incorporated into processed foods to increase dietary fibre content and/or serve as functional ingredients. This review focuses on research conducted in the past ten years on the non-starch polysaccharides and oligosaccharides found in dry beans (Phaseolus vulgaris), chickpeas (Cicer arietinum), lentils (Lens culinaris), and dry peas (Pisum sativum). The isolation, composition, and structure of these pulse fibres are described. Common terms used to describe the physicochemical properties of fibre fractions are defined and briefly discussed. Recent studies on the effects of processing on the ratio of insoluble to soluble dietary fibre and on the α-galacto-oligosaccharide content of pulses and fibre fractions are cited and summarized. Food applications for pulse fibre fractions and flours in fibre enrichment, nutrient enrichment, fat binding and retention, and texture modification, as well as some non-food applications, are reviewed.     

Kinematic wall friction properties of reed canary grass powder at high and low normal stresses

The effects of varying reed canary grass (RCG) powder moisture contents on the relationship between its coefficient of kinematic wall friction and normal stress were modelled, using experimental designs and multivariate analysis, at a range of both low (520 to 7520 Pa) and high (23 to 275 MPa) normal stresses. The coefficient of kinematic wall friction at low normal stresses (µ_L) correlated positively with moisture content and negatively with normal stress. Also, at high normal stresses, µ_H was negatively correlated to normal stress. A µ_H maximum was found at moisture contents of 13-15% and at the lowest normal stresses in the measurement range. The moisture content interval for the µ_H and RCG pellet durability maxima overlapped, suggesting that µ_H and RCG pellet durability are correlated.