Repeatable Analysis Research Articles

Pypette

Live digital forensics presents unique challenges with respect to maintaining forensic soundness, but also offers the ability to examine information that is unavailable to quiescent analysis. Any perturbation of a live operating system by a forensic examiner will have far-reaching effects on the state of the system being analysed. Numerous approaches to live digital forensic evidence acquisition have been proposed in the literature, but relatively little attention has been paid to the problem of identifying how the effects of these approaches, and their improvements over other techniques, can be evaluated and quantified. In this paper, the authors present Pypette, a novel platform enabling the automated, repeatable analysis of live digital forensic acquisition techniques.

The case for repeatable analysis with energy economy optimization models

Energy economy optimization (EEO) models employ formal search techniques to explore the future decision space over several decades in order to deliver policy-relevant insights. EEO models are a critical tool for decision-makers who must make near-term decisions with long-term effects in the face of large future uncertainties. While the number of model-based analyses proliferates, insufficient attention is paid to transparency in model development and application. Given the complex, data-intensive nature of EEO models and the general lack of access to source code and data, many of the assumptions underlying model-based analysis are hidden from external observers. This paper discusses the simplifications and subjective judgments involved in the model building process, which cannot be fully articulated in journal papers, reports, or model documentation. In addition, we argue that for all practical purposes, EEO model-based insights cannot be validated through comparison to real world outcomes. As a result, modelers are left without credible metrics to assess a model's ability to deliver reliable insight. We assert that EEO models should be discoverable through interrogation of publicly available source code and data. In addition, third parties should be able to run a specific model instance in order to independently verify published results. Yet a review of twelve EEO models suggests that in most cases, replication of model results is currently impossible. We provide several recommendations to help develop and sustain a software framework for repeatable model analysis.

Structured PDMS Chambers for Enhanced Human Neuronal Cell Activity on MEA Platforms

Structured poly(dimethylsiloxane) (PDMS) chambers were designed and fabricated to enhance the signaling of human Embryonic Stem Cell (hESC) – derived neuronal networks on Microelectrode Array (MEA) platforms. The structured PDMS chambers enable cell seeding on restricted areas and thus, reduce the amount of needed coating materials and cells. In addition, the neuronal cells formed spontaneously active networks faster in the structured PDMS chambers than that in control chambers. In the PDMS chambers, the neuronal networks were more active and able to develop their signaling into organized signal trains faster than control cultures. The PDMS chamber design enables much more repeatable analysis and rapid growth of functional neuronal network in vitro. Moreover, due to its easy and cheap fabrication process, new configurations can be easily fabricated based on investigator requirements.

In-Line Monitoring of Particulate, Color, and Water Content in Lubricating Oils to Facilitate Predictive Maintenance, Reduce Wear, and Provide Real Time Alarming

Abstract Imaging techniques for characterizing particle shapes and sizes in lubricating oils can be a valuable tool toward improving the life span and reliability of mechanical equipment. ASTM currently specifies several tests to monitor the condition of lube oil; however, most of these are off-line, lab based tests. Vision based systems are well designed to perform the examination of the lube oil, either in line or off line, as they are the only instrument systems that can determine particle shape, which is a critical parameter in determining the source of wear in a mechanical system. The visual capability allows the user to input his or her knowledge of the process to work in making meaningful analyses. Imaging filters can be applied to the analysis to sort through noise and focus on the important particle information that must be monitored. This paper describes a vision based system used for particle sizing that provides a true two-dimensional size and shape analysis. The paper also discusses the fundamentals of a vision system that allow for accurate and repeatable analysis of a wide range of processes.

Validated HPTLC method for simultaneous analysis of alfuzosin hydrochloride and dutasteride in a pharmaceutical dosage form

A sensitive, simple, selective, precise, and accurate HPTLC method for analysis of alfuzosin hydrochloride (ALF) and dutasteride (DUTA) both as the bulk drugs and in a tablet formulation has been developed and validated. TLC was performed on silica gel 60 F254 with toluene-methanol-dichloromethane-triethylamime 6:1:1:0.6 (ν/ν) as mobile phase. Densitometric evaluation of the separated zones was performed at 247 nm. Compact spots were obtained for ALF (RF 0.46 ± 0.03) and DUTA (RF 0.65 ± 0.03). Linear regression analysis data for the calibration plots revealed good linearity over the concentration ranges 300–600 ng per band for ALF and 500–1000 ng per band for DUTA. The method was validated for linearity, accuracy, precision, robustness, and recovery in accordance with ICH guidelines. There was no chromatographic interference from the tablet excipients. Statistical analysis showed the method enables repeatable and selective simultaneous analysis of these drugs in the tablet formulation and routine quality ...

COOPER-framework: A unified process for non-parametric projects

Practitioners assess performance of entities in increasingly large and complicated datasets. If non-parametric models, such as Data Envelopment Analysis, were ever considered as simple push-button technologies, this is impossible when many variables are available or when data have to be compiled from several sources. This paper introduces by the ‘COOPER-framework’ a comprehensive model for carrying out non-parametric projects. The framework consists of six interrelated phases: Concepts and objectives, On structuring data, Operational models, Performance comparison model, Evaluation, and Result and deployment. Each of the phases describes some necessary steps a researcher should examine for a well defined and repeatable analysis. The COOPER-framework provides for the novice analyst guidance, structure and advice for a sound non-parametric analysis. The more experienced analyst benefits from a check list such that important issues are not forgotten. In addition, by the use of a standardized framework non-parametric assessments will be more reliable, more repeatable, more manageable, faster and less costly.

Genetic diversity for gliadin patterns of durum wheat landraces in the Northwest of Iran and Azerbaijan

The objective of this study was to identify gliadin band patterns and the extent of genetic diversity in durum wheat genotypes from Northwestern Iran and the Republic of Azerbaijan. Gliadins from 46 landraces and four cultivars were evaluated through acid PAGE analyses. Sixty-six polymorphic bands and 81 patterns were identified. Twenty-four different motility bands and 22 patterns were found in the ω gliadin region with 14 polymorph bands and 20 patterns for α and γ gliadins, and 14 bands and 19 different patterns for β gliadins. The combination of these patterns generated 38 and 39 combinations for Gli-1 and Gli-2 loci, respectively. The genetic diversity index (H) was higher for α gliadins (0.924), followed by ω and γ gliadins (0.899 and 0.878, respectively), and for β gliadin patterns (0.866). Extensive polymorphism (H = 0.875) was observed in four gliadin pattern regions, with higher genetic diversity in the Iranian landraces than in the Azerbaijani ones. Each genotype had special identifying patterns in the gliadin acid PAGE analysis, and cluster analysis based on Jaccard's similarity coefficients formed six groups. Gliadin has a simple, repeatable and economic analysis, and can be used in genetic studies

Development and validation of a stability-indicating HPTLC method for analysis of rupatadine fumarate in the bulk drug and tablet dosage form

Summary A simple, selective, precise and stability-indicating high-performance thin-layer chromatographic method for analysis of rupatadine fumarate, both as the bulk drug and in a tablet formulation, has been developed and validated. Aluminium foil TLC plates precoated with silica gel 60F254 were used as stationary phase and toluene-methanol-triethylamine 4:1:0.2 (v/v) as mobile phase. A compact band (RF 0.61 ± 0.02) was obtained for rupatadine fumarate. Densitometric analysis was performed in absorbance mode at 264 nm. Linear regression analysis revealed a good linear relationship (r2 = 0.9992 ± 0.0001) between peak area and concentration in the range 400–1400 ng band−1. The mean values ± SD of the slope and intercept were 2.5471 ± 0.005 and 1055.2 ± 4.20, respectively. The method was validated for precision, recovery, and robustness. The limits of detection and quantitation were 66.63 and 201.91 ng band−1, respectively. Rupatadine fumarate was subjected to acid and alkaline hydrolysis, oxidation, and photochemical and thermal degradation and underwent degradation under all these conditions. Statistical analysis proved the method enables repeatable, selective, and accurate analysis of the drug. It can be used for identification and quantitative analysis of rupatadine fumarate in the bulk drug and in tablet formulations.

Delay Analysis under Multiple Baseline Updates

Windows delay analysis has been recognized as one of the most credible techniques for analyzing construction delays. To overcome some of the drawbacks of windows delay analysis, this paper introduces improvements to a computerized schedule analysis model so that it will produce accurate and repeatable results. The model considers multiple baseline updates due to changes in the durations of the activities and the logical relationships among them, as well as the impact of resource overallocation. The model uses a daily window size in order to consider all fluctuations in the critical path(s) and uses a legible representation of progress information to accurately apportion delays and accelerations among project parties. A simple case study has been implemented to demonstrate the accuracy and usefulness of the proposed delay analysis model. This research is useful for both researchers and practitioners and allows detailed and repeatable analysis of the progress of a construction project in order to facilitate corrective actions and claim analysis.

Multisphere phantom and analysis algorithm for PET image quality assessment

PET image quality measurements of lesion detectability frequently use a small, radioactive sphere in a larger phantom. The typical analysis of a small single sphere in background has several shortcomings as a measure for detectability and quantitation: the measurement has low statistical power; the region of interest (ROI) is susceptible to large pixel-to-pixel fluctuations; only a single point in the axial and transaxial field of view is analyzed; background noise measurements in regions away from the signal sphere may bias the detectability measurement and user-placed ROIs can cause inconsistent measurements. For a more robust measurement and repeatable analysis of small lesion detectability in PET images, a multisphere phantom and analysis algorithm were developed. The multisphere phantom consists of a collection of 50 1.0-cm spheres, mounting rods and a gridded plate. A PET/CT study is presented where 29 spheres with a 4:1 sphere-to-background radioactivity ratio were acquired for multiple frame durations and reconstructed. An analysis algorithm was implemented and applied to the acquired PET/CT that detects the contrast-enhanced spheres in a CT, places ROIs on the spheres and their respective proximal background, applies the ROIs to the PET and performs quantitation. Results are presented that show the impact of increasing number of signal spheres and of different background ROI placement methods on the image quality measurement. Increasing the number of spheres reduced the variability in the image quality measurements, but only up to a point, beyond which increasing the number of spheres did not considerably reduce the variability. A phantom with numerous spherical inserts increases several measurement aspects: the flexibility of sphere placement during setup, the number of radioactivity concentrations that can be used during a single study and the statistical power of measurements. Additionally, an automated algorithm that localizes spheres, places ROIs and performs quantitation will increase reliability and reproducibility of image quality assessment, in addition to simplifying the analysis.

Pisciforma, Setisura, and Furcatergalia (Order: Ephemeroptera) Are Not Monophyletic Based on 18S rDNA Sequences: A Response to Sun et al. (2006)

Sun et al. (2006) recently published an analysis of phylogenetic relationships of the major lineages of maysies (Ephemeroptera). Their study used partial 18S rDNA sequences (583 nucleotides), which were analyzed via parsimony to obtain a molecular phylogenetic hypothesis. Their study included 23 maysy species, representing 20 families. They aligned the DNA sequences via default settings in Clustal and reconstructed a tree by using parsimony in PAUP*. However, this tree was not presented in the article, nor have they made the topology or alignment available despite multiple requests. This molecular tree was compared with previous hypotheses based on morphological data to “test” (but see below) which morphology-based relationships were not signiÞcantly different from the molecular topology. Although molecular data can help shed light on many of the fundamental questions in insect phylogenetics, it is important to perform analyses correctly and to accurately report results in a way that allows subsequent validation. Sun et al. (2006) provided an adequate review of the major traditional hypotheses concerning higher level classiÞcation and relationships among maysies. Some of these hypotheses are based on cladistic analysis of morphology, but others are intuitive phylogenies that were not derived from any formal repeatable and objective analysis. These authors failed to report previously published molecular hypotheses that shed light on maysy phylogeny, many of which disagree with their results. For example, there have been previously published molecular studies investigating higher level relationships among maysies and relatives

Actual concepts of digital PAC-spectroscopy

In conventional perturbed angular correlation (PAC)-spectroscopy huge amounts of events are processed by fast electronics. Modern digital signal processing devices and the improvement in the computer technology in recent years allow today digital PAC-spectrometer setups capable to perform software-based data processing with all the benefits of storage, repeatable data analysis under different limits, and easy switching between different isotopes. In this paper we discuss experiences and concepts of a first realized digital PAC-spectrometer, which will be rebuild at ISOLDE/CERN/Geneva.

Electrochemical characterization of Geobacter sulfurreducens cells immobilized on graphite paper electrodes

Bacteria able to transfer electrons to conductive surfaces are of interest as catalysts in microbial fuel cells, as well as in bioprocessing, bioremediation, and corrosion. New procedures for immobilization of Geobacter sulfurreducens on graphite electrodes are described that allow routine, repeatable electrochemical analysis of cell-electrode interactions. Immediately after immobilizing G. sulfurreducens on electrodes, electrical current was obtained without addition of exogenous electron shuttles or electroactive polymers. Voltammetry and impedance analysis of pectin-immobilized bacteria transferring electrons to electrode surfaces could also be performed. Cyclic voltammetry of immobilized cells revealed voltage-dependent catalytic current similar to what is commonly observed with adsorbed enzymes, with catalytic waves centered at -0.15 V (vs. SHE). Electrodes maintained at +0.25 V (vs. SHE) initially produced 0.52 A/m(2) in the presence of acetate as the electron donor. Electrical Impedance Spectroscopy of coatings was also consistent with a catalytic mechanism, controlled by charge transfer rate. When electrodes were maintained at an oxidizing potential for 24 h, electron transfer to electrodes increased to 1.75 A/m(2). These observations of electron transfer by pectin-entrapped G. sulfurreducens appear to reflect native mechanisms used for respiration. The ability of washed G. sulfurreducens cells to immediately produce electrical current was consistent with the external surface of this bacterium possessing a pathway linking oxidative metabolism to extracellular electron transfer. This electrochemical activity of pectin-immobilized bacteria illustrates a strategy for preparation of catalytic electrodes and study of Geobacter under defined conditions.

A Method for Estimation of Free Mica Particles in Aggregate Fine Fraction by Image Analysis of Grain Mounts

The need to evaluate free mica grains in fine fraction of aggregate products has initiated the development of a statistically and scientifically acceptable method. The proposed method is based on a modified point-counting approach using digital micro photos of thin sections of aggregate grains and a software package to sustain sample analysis. A thin section of aggregate grains provides permanent sample documentation readily available for complimentary or other analysis. Statistical analysis, together with a repeatable analysis of samples (permanent mounts), confirms the robustness of the method. The method is appropriate as a complementary assessment tool to estimate and trace changes or variations in quality of rock aggregate. Though, the estimation of free mica particles in fine fraction needs to be combined with other analyses, e.g., petrographic analysis and analyses of mechanical properties, to assess the quality of any rock material. As the samples can be collected from drill cuttings, i.e., an accessible residual product obtainable from surveying or production, the present method is particularly useful as a surveying tool and in prospecting and projecting activities.

Enhanced anatomical calibration in human movement analysis

The representation of human movement requires knowledge of both movement and morphology of bony segments. The determination of subject-specific morphology data and their registration with movement data is accomplished through an anatomical calibration procedure (calibrated anatomical systems technique: CAST). This paper describes a novel approach to this calibration (UP-CAST) which, as compared with normally used techniques, achieves better repeatability, a shorter application time, and can be effectively performed by non-skilled examiners. Instead of the manual location of prominent bony anatomical landmarks, the description of which is affected by subjective interpretation, a large number of unlabelled points is acquired over prominent parts of the subject's bone, using a wand fitted with markers. A digital model of a template-bone is then submitted to isomorphic deformation and re-orientation to optimally match the above-mentioned points. The locations of anatomical landmarks are automatically made available. The UP-CAST was validated considering the femur as a paradigmatic case. Intra- and inter-examiner repeatability of the identification of anatomical landmarks was assessed both in vivo, using average weight subjects, and on bare bones. Accuracy of the identification was assessed using the anatomical landmark locations manually located on bare bones as reference. The repeatability of this method was markedly higher than that reported in the literature and obtained using the conventional palpation (ranges: 0.9–7.6 mm and 13.4–17.9, respectively). Accuracy resulted, on average, in a maximal error of 11 mm. Results suggest that the principal source of variability resides in the discrepancy between subject's and template bone morphology and not in the inter-examiner differences. The UP-CAST anatomical calibration could be considered a promising alternative to conventional calibration contributing to a more repeatable 3D human movement analysis.

Kinetic of the hydrolysis of pectin galacturonic acid chains and quantification by ionic chromatography

These experiments were designed to develop a rapid, repeatable and accurate analysis method for the quantification of galacturonic acid of pectins. Different pectin hydrolysis procedures (chemical and enzymatic) were carried out with H 2SO 4, TFA and HCl at different acid concentrations (0.2, 1 and 2 M) and temperatures (80 and 100 °C). Enzymatic and combined chemical and enzymatic hydrolysis of pectin were also studied. A acid hydrolysis under drastic conditions (100 °C) is insufficient for complete hydrolysis and results in low recovery of galacturonic acid residues. Mild chemical hydrolysis (0.2, 1 and 2 M H 2SO 4 72 h at 80 °C) is also insufficient for complete depolymerization. Its main advantage is cleavage of the galacturonic acid chains into oligomeric forms without any degradation within 72 h of hydrolysis. However, enzymatic hydrolysis with VL9 for 2 h at 50 °C and combined chemical and enzymatic hydrolysis (0.2 M TFA at 80 °C for 72 h and VL9) give high recovery of this acid. Analysis of the liberated sugar residue by HPAEC allows us to determine the galacturonic acid composition of this polysaccharide accurately with high selectivity and sensitivity in one assay without the need for derivatization.

Can the Theory of Planned Behavior Predict the Maintenance of Physical Activity?

This study tested the ability of the theory of planned behavior to predict actual participation in physical activity and explored the development of activity habits in a 12-week longitudinal study. People enrolling in a gymnasium (N = 94) completed standard theory of planned behavior measures at baseline and follow-up; behavior was monitored objectively in the intervening period. The data were analyzed by using both standard and repeatable events survival analysis. Results showed that (a) perceived behavioral control was significantly predictive of intentions and actual behavior, (b) stable exercise habits developed in the first 5 weeks of the study, and (c) successful prior performance enhanced perceptions of behavioral control. The implications for developing theory-based interventions that promote the maintenance of health behavior are discussed.

Determination of Residual Methylmethacrylate Monomer in Denture Base Resins by Gas Chromatography

Acrylic base resins are widely used in orthopedics and dental surgery. It is generally accepted that due to the incomplete conversion of methyl methacrylate (MMA) monomer to the polymer form during polymerization of the resin, some MMA monomers remain in the hardened material. MMA monomer has been reported to cause abnormalities or lesions in several organs of animals. Study of the literatures showed that there are no perfect and valid methods for analysis of MMA. The aim of this study was to develop a simple and valid method for determination of MMA residual monomer in the denture base resins. We have developed and validated an analytical procedure employing gas chromatography with flame ionization detector (GC-FID), with temperature programming, and a close analogue internal standard for fast and repeatable analysis of MMA residual monomer contents in denture base polymers. For quantification of monomer, two calibration curves were used by two different methods of solution preparation and they were compared to each other. The assay was linear over the range of 0.03-0.6 mg/ml MMA with correlation coefficients (r 2 ) of greater than 0.99. Accuracy, intra-day (Error<9.1%) and inter-day (Error<6.6%) , precision (RSD<5.5% and RSD<6.5%, respectively) were in acceptable values over the examined concentration range. Limit of detection (LOD) and limit of Quantification (LOQ) for MMA were 0.01 and 0.02 mg/ml, respectively. In conclusion, the proposed method was a simple and fast assay for MMA residual monomer in denture base resins.

화상분석법을 통한 경화 콘크리트의 미세 공극 구조 분석

Air voids in hardened concrete have an important influence on concrete durability such as freeze-thaw resistance, surface scaling resistance, and water permeability, and they have been characterized by spacing factor Linear traverse and point count methods in ASTM standard have been used in estimating an air void system in hardened concrete. However, these methods require lots of time and efforts, further they are not repeatable. Image analysis method could be utilized In estimating an air void systems in hardened concrete with a developments of microscope, digital camera and computer program. The purpose of this study was to develope image analysis method and provide a guideline by comparing the results from ASTM method and image analysis method. The concerns were at air void content and diameter distribution, air voids system as well as spacing factors. The experimental variables included air content by air entrained agent (0, 0.01, ) and depth of specimen (top, middle, bottom). The result showed that it was possible to calculate spacing factor using image analysis technique, as well as air content, air diameter distribution, and air structure. This study also contributed in developing an reasonable and repeatable image analysis method.

Boundary-layer isotope dilution/mass balance methods for measurement of nocturnal methane emissions from grazing sheep

Following advances with methods for 13C/ 12C isotopic analysis of methane in small (⩽4 L) air samples, new isotope dilution techniques are proposed for measurement of methane emissions at the paddock scale from grazing ruminant animals. These techniques combine measurement of the isotopic δ 13CH 4 composition of air samples with a non-intrusive mass balance method applied in the nocturnal boundary layer. Flux estimates from trials using the isotope dilution techniques are compared with estimates based on scaling up individual animal emission measurements using a rumen gas tracer technique. The methane flux assessed by the latter technique ranged from 35 to 70 mg (CH 4) m −2 d −1 with a stocking density between 10 and 20 sheep ha −1. The isotope dilution based nocturnal boundary-layer estimates generally agreed to better than a factor of 2 and usually to within 20% of the average of individual animal emission rate per unit area of paddock. Both static and advecting mass balance methods are developed. In the advecting case, the upwind/downwind contrast in δ 13C was typically 0.2–0.5‰. Care was necessary with air sampling to avoid error in this small contrast contributing to error in the flux. Agreement between concentration- and isotope-based nocturnal boundary layer methods and the sheep breath measurements indicated that sample representativeness was generally good. Factors which affect the accuracy of the method are examined and include variability in nocturnal mixing height, the assumed δ 13CH 4 composition of the source sheep breath and diurnal patterns in sheep emission. This paper establishes new techniques useful in the paddock to landscape scale although widespread application awaits further development of technology for rapid and repeatable field analysis of δ 13CH 4 in small samples.