Location Error Spatial Distribution in Urban Wireless Cellular Networks

In this work the spatial distribution of the location error in wireless cellular networks operating in an urban outdoor environment is studied. We assume signal strength based positioning methods that avoid additional network hardware costs and handset modifications, while approaching FCC requirements for emergency positioning. In order to cope with the computational burden associated with the required spatial discrimination of our analysis, we developed an efficient simulator that is capable of analyzing a comprehensive class of cost efficient location algorithms based on the received signal strength measurements made periodically by the mobile terminals in GSM and UMTS systems. The simulation results show that the key factors to achieve positioning accuracy are line-of-sight and homogeneous distribution of base stations in the vicinity of the mobile terminals, leading to the conclusion that the positioning error is location dependent. This conclusion motivates a reliability analysis based on the spatial segmentation of the location process. In the same scenario we estimate the a posteriori location probabilities providing a framework for the further development of reliable methodologies for the tracking of mobile terminals.     

Multicenter Collaborative Trial Evaluation of a Method for Detection of Human Adenoviruses in Berry Fruit

The qualitative performance characteristics of a qPCR-based method to detect human adenoviruses in raspberries were determined through a collaborative trial involving 11 European laboratories. The method incorporated a sample process control (murine norovirus) and an internal amplification control. Trial sensitivity or correct identification of 25-g raspberry samples artificially contaminated with between 5?×?10² and 5?×?10⁴?PFU was 98.5%; the accordance and concordance were 97.0%. The positive predictive value was 94.2%. The trial specificity or percentage correct identification of non-artificially contaminated samples was 69.7%; the accordance was 80.0% and the concordance was 61.7%. The negative predictive value was 100%. Application of a method for the detection of human adenoviruses in food samples could be useful for routine monitoring for food safety management. It would help to determine if a route of contamination exists from human source to food supply chain which pathogenic viruses such as norovirus and hepatitis A virus could follow.     

Measurement of the bending strength of vapor-liquid-solid grown silicon nanowires

The fracture strength of silicon nanowires grown on a [111] silicon substrate by the vapor-liquid-solid process was measured. The nanowires, with diameters between 100 and 200 nm and a typical length of 2 microm, were subjected to bending tests using an atomic force microscopy setup inside a scanning electron microscope. The average strength calculated from the maximum nanowire deflection before fracture was around 12 GPa, which is 6% of the Young's modulus of silicon along the nanowire direction. This value is close to the theoretical fracture strength, which indicates that surface or volume defects, if present, play only a minor role in fracture initiation.     

Detail-driven digital hologram generation

Digital holography is a technology with a potential to provide realistic 3D images. However, generation of digital holograms is a computationally demanding task. Thus, the performance is a major concern. We propose a new method that reduces spatial resolution in order to accelerate hologram generation. It employs the propagation between parallel planes for efficient optical field values evaluation and a computer graphics approach for approximating visibility. Our results show that the proposed reduction has only a minimal impact on the visual quality, while the formal computational complexity confirms performance improvement.     

Enzymatic Construction of Artificial Base Pairs: The Effect of Metal Shielding

Th formation of metal base pairs is a versatile method for the introduction of metal cations into nucleic acids that has been used in numerous applications including the construction of metal nanowires, development of energy, charge-transfer devices and expansion of the genetic alphabet. As an alternative, enzymatic construction of metal base pairs is an alluring strategy that grants access to longer sequences and offers the possibility of using such unnatural base pairs (UBPs) in SELEX experiments for the identification of functional nucleic acids. This method remains rather underexplored, and a better understanding of the key parameters in the design of efficient nucleotides is required. We have investigated the effect of methylation of the imidazole nucleoside ( dIm ^{n Me} TP ) on the efficiency of the enzymatic construction of metal base pairs. The presence of methyl substituents on dImTP facilitates the polymerase-driven formation of dIm^4Me −Ag^I− dIm and dIm^2MeTP −Cr^III− dIm base pairs. Steric factors rather than the basicity of the imidazole nucleobase appear to govern the enzymatic formation of such metal base pairs. We also demonstrate the compatibility of other metal cations rarely considered in the construction of artificial metal bases by enzymatic DNA synthesis under both primer extension reaction and PCR conditions. These findings open up new directions for the design of nucleotide analogues for the development of metal base pairs.     

Rapid Payne effect test—A novel method for study of strain‐softening behavior of rubbers filled with various carbon blacks

In the presented article, the strain‐softening process in rubber compounds filled with carbon black is investigated. First people to observe this process were Fletcher and Gent in 1954. Later, Payne did an extensive investigation of the process thus the test is generally known as Payne effect test. Based on the measured data, so‐called Payne softening can be calculated. The Payne softening is broadly considered as the measure of the strain‐softening. In order to investigate strain‐softening behavior of a filled rubber compound several strain amplitudes are imposed during a Payne effect test. In this article, a two‐point (rapid) version of the test containing only two strain amplitudes is introduced and verified statistically. This test has shown that for the investigation of the filler network disintegration in filled rubbers primarily the large deformations are important, notwithstanding the strain history of a sample. Moreover, the softening characteristic is observed in 30% of the time of the original test. The new method is exemplified for a study of three different rubbers filled with various carbon blacks. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41976.     

Digitally reconstructing Van Gogh's Field with Irises near Arles. Part 2: Pigment concentration maps

Colors in many paintings of great art historical value have changed over time, due to the combined effects of natural ageing, accumulated surface grime, and materials added during later conservation treatments. The physical restoration of the colors in such paintings is not possible. This article describes one part of work done to digitally restore the colors of Van Gogh's painting Field with Irises near Arles, dating from May 1888. We have used multispectral reflectance data to estimate absorption K and backscattering S parameters of Kubelka‐Munk 2‐constant theory. This was done for all 13 pigments known to have been used by Van Gogh in this painting, and based on this the concentration maps for each of these pigments were calculated. We validated the calculated concentration maps in several ways. For some pigments, we were able to predict spots on the painting where the pigment is expected to occur in unmixed form based on visual examination. For several other pigments, the concentration maps could be shown to agree with XRF data. Finally, for some other pigments the concentration maps were supported by additional evidence from microscopic examinations, remarks in Van Gogh's letters and from early color reproductions. For the 1.7 million pixels for which multispectral data is available, the average color difference between the calculated and measured spectral reflectance curves is CIEDE2000 = 1.05. This further confirms that the Kubelka‐Munk calculations are well suited to describe the variety of spectral reflectance on the painting.     

Production and characterization of oxidized cassava starch (Manihot esculenta Crantz) biodegradable films

Plastic is one of the most common pollutants in the environment. Therefore, the number of studies on the use of biodegradable packaging is increasing. Starch is the primary material used in the production of biodegradable plastics due to its natural abundance and high biodegradability. Yet, the strong hydrophilic character of starch presents a challenge. Therefore, the modification of its structure through oxidation may yield interesting results as the viscosity reduction. The objectives of this work were to obtain cassava (Manihot esculenta Crantz) starch oxidized with 0.8 and 2.0% active chlorine, to develop biodegradable films and characterize their mechanical properties, solubility in water, permeability to water vapor, degree of swelling, and sorption isotherms. Biodegradable films were produced with starch concentrations of 2, 3, 4, and 5% w/w and 25% glycerol (g/100 g starch) added as a plasticizer. Images of the films were obtained with an atomic force microscope and allow to observe a smooth surface and the absence of starch granules in the film produced with oxidized starches. The tensile strength of the biodegradable film produced with oxidized starch (0.8% active chlorine) was 80 MPa. The value of permeability to water vapor was 1.613 × 10⁻⁹ kg/day/m/Pa, and the average solubility was 41%. The sorption isotherms showed that biodegradable films made with oxidized starches cannot be used in environments with relative humidity below 35% or above 90%.