Attributing Meanings to Representations of Data: The Case of Statistical Process Control

This article is concerned with the meanings that employees in industry attribute to representations of data and the contingencies of these meanings in context. Our primary concern is to more precisely characterize how the context of the industrial process is constitutive of the meaning of graphs of data derived from this process. We draw on data from a variety of sources, including ethnographic studies of workplaces and reflections on the design of prototype learning activities, supplemented by insights obtained from trying out these activities with a range of employees. The core of this article addresses how different groups of employees react to graphs used as part of statistical process control, focusing on the meanings they ascribe to mean, variation, target, specification, trend, and scale as depicted in the graphs. Using the notion of boundary crossing, we try to characterize a method that helps employees to communicate about graphs and come to data-informed decisions.     

Possibilities for human skin characterization based on strongly reduced Raman spectroscopic information

Loss‐of‐function mutations in the gene coding for filaggrin are the single most important risk factor for development of atopic dermatitis and associated allergic rhinitis and asthma. Filaggrin is enzymatically degraded to natural moisturizing factor (NMF) in the stratum corneum (SC). In vivo Raman spectra of human skin can be used to quantify the NMF concentration in SC and thereby identify carriers of a loss‐of‐function mutation in the gene coding for filaggrin, which results in decreased NMF content. Here, we demonstrate that strongly reduced Raman spectral information is sufficient to make this differentiation. This is an important step towards development of a dedicated diagnostic device of reduced complexity, size and cost as compared to current state‐of‐the‐art Raman equipment. A genetic algorithm was used to select the spectral regions needed to classify skin based on normal or reduced NMF content in SC. Using the NMF content based on full spectral information as gold standard, only four Raman regions were required to create a linear discriminant analysis model that can differentiate between skin with low NMF and skin with normal NMF with a prediction accuracy of 93 %. Copyright © 2013 John Wiley & Sons, Ltd.     

Bonding rearrangement in amorphous silicon nitrides deposited by hot-wire chemical vapor deposition upon thermal annealing

The bonding rearrangement upon thermal annealing of amorphous silicon nitride (a-SiN_x:H) films deposited by hot-wire chemical vapor deposition was studied. A wide range of N/Si atom ratio between 0.5 and 1.6 was obtained for the a-SiN_x:H sample series by varying the source gases ratio only. Evolutions of Si–N, Si–H and N–H bonds upon annealing were found to depend strongly on the N/Si atom ratio of the films. According to the above observations, we propose possible reaction pathways for bonding rearrangement in a-SiN_x:H with different N/Si ratios.     

Absorbance characterization of microsphere-based ion-selective optodes

Ionophore-based microsphere sensors are characterized here in transmission mode. These sensors contain a lipophilic ionophore for the analyte cation, a chromoionophore for recognizing H⁺, and a lipophilic cation-exchanger. They function on the basis of an ion-exchange equilibration step where an increased concentration of analyte ion leads to increased level of extraction into the bulk of the microsphere, expelling protons in return and deprotonating the chromoionophore. Since the path length is variable across the microsphere, such bead-based sensors are normally characterized in fluorescence mode. In this paper, the response of the sensing microspheres is calculated from the ratio of transmitted light intensities at the absorbance peak maxima of the protonated and unprotonated forms of the chromoionophore. At a fixed position of the particle, the resulting responses are found to be independent of light scattering, incident light intensity and the shape or size of the microsphere. The responses of potassium-selective microspheres obtained by this method agree quantitatively with corresponding fluorescence-based data.     

Reproducible manufacturing of dye‐sensitized solar cells on a semi‐automated baseline

A fully operational baseline consisting of dedicated equipment to process nanocrystalline dye‐sensitized solar cell devices has been installed at ECN. This baseline focuses on the production of glass/glass devices with dimensions up to 10×10 cm². Present power conversion efficiencies of 6% obtained for cell areas of 2ċ5 cm² are successfully translated to 100 cm² devices with an active area of 68 cm² by application of identical cell components. The power conversion efficiency with respect to total area was 4%. Processing of a large number of devices in the baseline shows good results in terms of process reliability and yield. The overall yield for a series of 27 devices (10×10 cm²) was 96%, while 84% (22 of the remaining 26 devices) generated a cell efficiency within 7% deviation from the average value (4ċ3%). The reproducibility of the titanium dioxide (TiO₂) colloid synthesis has been investigated. The deviation from the average efficiency (4ċ9%) of three batches of colloid was at most 3ċ2%. These results prove that complete device manufacturing of nc‐DSC by a baseline process, starting with colloid synthesis is reproducible for surfaces up to 10×10 cm². Copyright © 2003 John Wiley & Sons, Ltd.     

Automated precolumn derivatization device to determine neurotransmitter and other amino acids by reversed-phase high-performance liquid chromatography

A device to derivatize amino acids with o-phthaldialdehyde, which is directly connected to high-performance liquid chromatographic equipment is described. Its principle is that a sample (10-500 microliters) is mixed with a reagent (containing o-phthaldialdehyde, 2-mercaptoethanol and sodium hydrogen carbonate buffer), using a peristaltic pump. This mixture is pumped into a loop of a pneumatically controlled injection valve at atmospheric pressure. When the derivatization is complete the valve switches, so that the sample is applied to a column and the amino acid derivatives are separated with a gradient of methanol-phosphate buffers. The reproducibility is such that brain perfusates or tissue extracts can be analyzed for the amino acid transmitter content and no internal standard is necessary. The major advantages of the present device are that it produces thorough mixing of reagent and sample, so that a high and constant degree of derivatization occurs (thus producing high sensitivity; less than 0.1 pmol can be detected) and its low cost.     

Effect of Air-excess on Blends of RON70 Partially Premixed Combustion

Partially Premixed Combustion (PPC) is a combustion concept that aims to provide combustion with low smoke and NOx emissions and a high thermal efficiency. Extending the ignition delay to enhance premixing, avoiding spray-driven combustion, and controlling temperature at an optimum level through use of suitable dilution levels has been recognized as a key factor to achieve such a concept. Fuels with high auto-ignition resistance do extend ignition delay. In this work three ternary blends of an alcohol (ethanol or n-butanol), n-heptane and iso-octane with a target research octane number (RON) of 70 are studied. RON70 was earlier found to be close to optimal for PPC over a large load range. The objective of this research is to analyze the sensitivity of the combustion parameters to changes in air-excess ratio when using these three blends. The engine was operated at 1250 rpm and 1000 bar injection pressure with a single injection strategy. Results revealed that efficiency was increased from rich to lean combustion, and these three blends show distinct premixed combustion even in lean PPC operation. The premixed fraction of combustion however reduces with the increase of air-excess ratio, which is especially apparent for PRF70 which consists of n-heptane and iso-octane alone.     

Selective depiction of susceptibility transitions using Laplace-filtered phase maps

In this work, we aim to demonstrate the ability of Laplace-filtered three-dimensional (3D) phase maps to selectively depict the susceptibility transitions in an object. To realize this goal, it is first shown that both the Laplace derivative of the z component of the static magnetic field in an object and the Laplacian of the corresponding phase distribution may be expected to be zero in regions of constant or linearly varying susceptibility and to be nonzero when there is an abrupt change in susceptibility, for instance, at a single point, a ridge, an interface, an edge or a boundary. Next, a method is presented by which the Laplace derivative of a 3D phase map can be directly extracted from the complex data, without the need for phase unwrapping or subtraction of a reference image. The validity of this approach and of the theory behind it is subsequently demonstrated by simulations and phantom experiments with exactly known susceptibility distributions. Finally, the potential of the Laplace derivative analysis is illustrated by simulations with a Shepp-Logan digital brain phantom and experiments with a gel phantom containing positive and negative focal susceptibility deviations.     

Review of inventory systems with deterioration since 2001

This paper presents an up-to-date review of the advances made in the field of inventory control of perishable items (deteriorating inventory). The last extensive review on this topic dates back to 2001 (Goyal S.K. and Giri B.C., Recent trends in modeling of deteriorating inventory, European Journal of Operational Research, 134, 1–16). Since then, over two hundred articles on this subject have been published in the major journals on inventory control, indicating the need for a new review. We use the classification of Goyal and Giri based on shelf life characteristics and demand characteristics. Contributions are highlighted by discussing main system characteristics, including price discounts, backordering or lost sales, single or multiple items, one or two warehouses, single or multi-echelon, average cost or discounted cash flow, and payment delay.     

UV-B absorbance and UV-B absorbing compounds (para-coumaric acid) in pollen and sporopollenin: the perspective to track historic UV-B levels.

UV-B absorbance and UV-B absorbing compounds (UACs) of the pollen of Vicia faba, Betula pendula, Helleborus foetidus and Pinus sylvestris were studied. Sequential extraction demonstrated considerable UV-B absorbance both in the soluble (acid methanol) and insoluble sporopollenin (acetolysis resistant residue) fractions of UACs, while the wall-bound fraction of UACs was small. The UV-B absorbance of the soluble and sporopollenin fraction of pollen of Vicia faba plants exposed to enhanced UV-B (10 kJ m(-2) day(-1) UV-B(BE)) was higher than that of plants that received 0 kJ m(-2) day(-1) UV-B(BB). Pyrolysis gas chromatography-mass spectrometry (py-GC-MS) analysis of pollen demonstrated that p-coumaric acid and ferulic acid formed part of the sporopollenin fraction of the pollen. The amount of these aromatic monomers in the sporopollenin of Vicia faba appeared to increase in response to enhanced UV-B (10 kJ m(-2) day(-1) UV-B(BE)). The detection limit of pyGC-MS was sufficiently low to quantify these phenolic acids in ten pollen grains of Betula and Pinus. The experimental data presented provide evidence for the possibility that polyphenolic compounds in pollen of plants are indicators of solar UV-B and may be applied as a new proxy for the reconstruction of historic variation in solar UV-B levels.