Sequential Analysis Technique Research Articles

Determination of Cd and Zn by isotope dilution–thermal ionisation mass spectrometry using a sequential analysis procedure

Isotope dilution–thermal ionisation mass spectrometry (ID-TIMS) was used to examine the certified Cd and Zn content of 4 Certified Reference Materials (CRMs); 2 soils: GBW07401 and GBW07405, 1 plant CRM060 and an animal tissue SRM1566a. The CRMs were chosen to be of contrasting origin and Cd:Zn content. Three digestion procedures were compared: (i) an open tube aqua regia procedure (ii) microwave digestion using Teflon bombs and (iii) hydrofluoric acid (HF) digestion using PTFE bombs. The Cd and Zn levels obtained using ID-TIMS all fell within the published certified range for the CRMs. This was the case regardless of the digestion procedure used, although HF digestion tended to yield marginally higher levels than the other procedures and in one instance, Cd in GBW07401, was significantly different ( P<0.05) from the certified range. A filament loading procedure was developed, to allow sequential analysis of Cd and Zn on the same single filament during thermal ionisation mass spectrometry analysis. The sequential analysis technique was evaluated to ensure that Zn did not fractionate during Cd analysis and there was no inter-element interference. No marked difference in the precision and accuracy of the isotope ratio measurements were obtained from sequential element analyses on the same filament when compared to individual element analyses for a range of standard solutions or for sample digests. The most efficient procedure in terms of costs and productivity for future work of this kind would be a combination of microwave digestion and sequential analysis of Cd and Zn on the same filament.

Sequential analysis for quality control in the neonatal intensive care unit

Objective: This article describes a novel application of a statistical technique for continuous quality assurance in the NICU. Methods: We used prospective analysis of rates of survival to 28 days of life, without major IVH in ELBW infants in a single tertiary NICU, before and after the introduction of an evidence-based treatment protocol. By using the CUSUM function, each infant's results were sequentially plotted, and significant changes in outcomes were noted when the plot crossed predetermined boundary lines. Results: Significant changes in outcomes were evident with this method sooner than traditional analyses on the basis of year-end or other arbitrary intervals. The introduction of the ELBW protocol was temporally associated with significant improvement in intact short-term survival. Conclusion: Sequential analysis techniques are useful tools for ongoing quality assurance; deviations in outcomes may be detected more quickly, which should assist in the identification of improvements or decrements in performance of the NICU. (J Pediatr 2001;139:778–84)

Determination of procaine, benzocaine and tetracaine by sequential injection analysis with permanganate-induced chemiluminescence detection

Local anaesthetics procaine hydrochloride ( I), benzocaine ( II), and tetracaine hydrochloride ( III) were determined by the technique of sequential injection analysis (SIA) with chemiluminescence (CL) detection. The CL was emitted during the oxidation of the analytes by permanganate in aqueous sulphuric acid in the presence of various CL enhancers (4-hydroxybiphenyl, Rhodamine B, glycolaldehyde, glutaraldehyde and formic acid). The optimum enhancer or reagent concentrations, order and volumes of the injected zones were: 0.37 M formic acid (40, 23 or 28 μl for I– III, respectively), sample (40 μl), 2.3 M H 2SO 4 (20, 16 or 18 μl for I– III, respectively), and 0.5 mM KMnO 4 (19, 13 or 15 μl for I– III, respectively). After a double (or single for III) reversal of the flow the mixed zone was pushed into the detector at a flow rate of 100 μl s −1. The transient CL signal was recorded at ≥390 nm. The calibration graphs relating the intensity of the emission (peak heights) to the concentration of the analytes were curvilinear (a second order polynomial showed the best fit) and they were suitable for determining I– III in the ranges 0.5–50, 0.5–25 and 0.2–25 μg ml −1, respectively. The limits of detection (3 σ) were 0.3 μg ml −1 for I and II and 0.1 μg ml −1 for III. The sample throughput was 120 h −1. The relative standard deviations were ≤3.8% ( n=10) when determining 5 μg ml −1 of I– III in prepared pure test solutions. The I and II were assayed in pharmaceutical dosage forms by the proposed method and the SIA results did not show any statistically significant difference from those obtained by standard titrimetry with sodium nitrite.

A young man referred to specialist secure accommodation

Young people referred to secure residential provision often present with a multitude of adverse childhood experiences, and it is frequently these dysfunctional backgrounds which prove to be the instigators of their current severely disruptive and antisocial behaviour. This paper presents a case of a young man referred to a specialist secure unit for juveniles, namely the Glenthorne Centre in Birmingham. The aim was to explore the background factors acting as possible instigators of, and reinforcers for, his current behaviour. Analysis was carried out using the multiple sequential functional analysis technique. Copyright © 1999 John Wiley & Sons, Ltd.

Design Visualization and Collaborative Interaction in Undergraduate Engineering Teams

Design team meetings are assumed to provide a creative forum in which designers can interactively shape new product ideas. However, the collaborative processes that take place within these meetings are poorly understood, and this presents an obstacle to the development of new technologies for sup- porting interactive design. We report a study in which video recordings of small teams of final-year engineering design students working on realistic design consultancy briefs were analyzed into event sequences and coded for type of design reasoning (visual, nonvisual), drawing space activity (sketching, pointing, and figural gesturing), and conversational grounding (the exchange of positive evidence of mutual understanding). Using exploratory sequential data analysis techniques, 2 interactional patterns were found to differentiate visual and nonvisual design sequences: (a) visual sequences were longer and less interactive than nonvisual sequences, often comprising uninterrupted bursts of design ideas from singl...

Surface evaluation of the silver finishes via sequential electrochemical reduction analysis (SERA)

This paper extends our study of the sequential electrochemical reduction analysis (SERA) technique for evaluation of various alternative finishes and it discusses the application of the SERA technique to assess the surface conditions of the silver finish. The tarnishing products of the silver formed under ambient and artificially created conditions were analyzed, the protective effect of an anti‐ tarnishing film was evaluated, and the influence of the elevated temperatures (reflow) on the stability of the organic inhibitor and the formation of the tarnishing film will be shown.

Poly-FISH: a technique of repeated hybridizations that improves cytogenetic analysis of fetal cells in maternal blood

Prenatal diagnosis of fetal chromosomal abnormalities using interphase fetal nucleated erythrocytes (FNRBCs) separated from maternal peripheral blood can be technically challenging due to the limited number of FNRBCs available for analysis, the limited number of probes that can be used simultaneously, and low FISH efficiency on the formaldehyde-fixed and immunohistochemically stained interphase FNRBCs. We developed a technique of sequential FISH analysis that involves removal of the previous hybridized probe under denaturing conditions, and rehybridization with different probes to improve FISH efficiency. This technique facilitates the analysis of multiple chromosome-specific probes on the same nuclei. Results from our experiments show that FISH can be performed at least nine times on the same interphase nucleus and at least three different probes can be used simultaneously. Thus, theoretically, at least 24 different chromosomes can be analysed on a single interphase fetal cell isolated from maternal blood. We have termed this technique 'Poly-FISH', and have successfully diagnosed trisomy 21, triploidy, and other chromosome abnormalities in FNRBCs using this technique.

Poly‐FISH: a technique of repeated hybridizations that improves cytogenetic analysis of fetal cells in maternal blood

Prenatal diagnosis of fetal chromosomal abnormalities using interphase fetal nucleated erythrocytes (FNRBCs) separated from maternal peripheral blood can be technically challenging due to the limited number of FNRBCs available for analysis, the limited number of probes that can be used simultaneously, and low FISH efficiency on the formaldehyde-fixed and immunohistochemically stained interphase FNRBCs. We developed a technique of sequential FISH analysis that involves removal of the previous hybridized probe under denaturing conditions, and rehybridization with different probes to improve FISH efficiency. This technique facilitates the analysis of multiple chromosome-specific probes on the same nuclei. Results from our experiments show that FISH can be performed at least nine times on the same interphase nucleus and at least three different probes can be used simultaneously. Thus, theoretically, at least 24 different chromosomes can be analysed on a single interphase fetal cell isolated from maternal blood. We have termed this technique ‘Poly-FISH’, and have successfully diagnosed trisomy 21, triploidy, and other chromosome abnormalities in FNRBCs using this technique. Copyright © 1998 John Wiley & Sons, Ltd.

Prediction of Layer Moduli from Falling Weight Deflectometer and Surface Wave Measurements Using Artificial Neural Network

A new algorithm for predicting layer moduli using measurements from both falling weight deflectometer (FWD) and surface wave tests is presented. This algorithm employs numerical solutions of a multilayered half-space based on Hankel transforms as a forward model and an artificial neural network (ANN) for the inversion process. Phase velocities for frequencies ranging from 10 Hz to 10,000 Hz are calculated using the forward model for varying pavement structures with a range of layer moduli and thicknesses. These phase velocities, along with the layer moduli and thicknesses, are used to train an ANN to backcalculate layer moduli from dispersion curves (i.e., phase velocity versus frequency curves) constructed from the FWD and stress wave test data. To account for the effect of bedrock on the moduli prediction, another network is trained with layer thicknesses and phase velocities for predicting the depth to bedrock. Combining this network with the network for the moduli prediction results in a sequential dispersion analysis technique in which the depth to bedrock predicted from the first network becomes an input to the second network for predicting layer moduli. FWD and stress wave test measurements from an intact pavement and an asphalt overlay over cracked asphalt layer are processed using the sequential dispersion analysis technique and MODULUS 5.0 backcalculation program. Comparison of the results indicates that the dispersion analysis technique yields less variable subgrade moduli and is more sensitive to changes in the asphalt surface layer, because the high-frequency data from the stress wave test is incorporated.

Classroom Interaction Evaluation Through Sequential Analysis of Observational Data

In this paper, an example of research in which interaction within the classroom is evaluated using a technique of sequential analysis starting from log-linear and logit models is presented. The research was carried out among students in their last year of secondary school (17-18 year olds). The general aim was to improve the teaching-learning environment through evaluating interaction. The context of study, the categorization process, the records and the observational sampling carried out and the records obtained and briefly described, are sequentially analyzed using log-linear and especially logit models, and by placing special emphasis on the concordance of the observational measurement . From the chosen model, a set of aspects of great interest is studied in depth to examine the interpretation of the results (mainly the adjusted residuals and the -ers estimated from the model). Finally, there is a discussion about a series of considerations relating to the choice of the logit models and to the usefulness and applicability of the sequential analysis in the evaluation of interaction in educational contexts.

Grammatical Models of Organizational Processes

Grammar has been used metaphorically to describe organizational processes, but the metaphor has never been systematically developed so that it can be applied in empirical research. This paper develops the grammatical metaphor into a rigorous model for describing and theorizing about organizational work processes, defined here as sequences of actions that occur in the context of enabling and constraining structures. A grammatical model starts with a lexicon of elementary actions (called moves) and specifies the ways in which they can be combined to create a process. Unlike other sequential data analysis techniques, grammatical models provide a natural way of describing the layering and nesting of actions that typifies organizational processes. The example of a simple retail sales transaction is used to illustrate the underlying concepts. The paper also examines some methodological considerations involved in using process grammars and proposes an agenda for research, including: (1) creating descriptive taxonomies of organizational processes; (2) creating disconfirmable theories about the relationship between processes and the structures that enable and constrain them; (3) explaining the distribution of observed processes and predicting new processes that have not yet been observed; and (4) designing new organizational processes.

Understanding the applicability of sequential data analysis techniques for analysing usability data

Abstract The applicability of sequential data analysis (SDA) techniques for analysing usability test data is examined. SDA techniques include transition matrix analysis, lag sequential analysis, frequency of cycles, graphical summarization techniques, and pattern analysis techniques. A subset of each was used in analysing the data from three usability studies. The encoding schemes used, the analysis routines run, software tools to support encoding and analysis (SHAPA and the Maximal Repeating Pattern analysis tool), and their interactions are discussed. The different types of usability problems which can be extracted from the data when analysed with SDA techniques are illustrated. It is concluded that the SDA techniques will be useful once the state-of-the-art in software support is able to provide the analyst greater flexibility in applying the analysis routines. Without the ability to apply analysis routines to multiple data levels, too much work is involved in obtaining a complete analysis of usability problems at all levels.

A Biostratigraphic Sequence Analysis in Cretaceous Sediments from Eastern Venezuela

This paper presents the results of a high resolution biostratigraphic study integrated with petrophysic analyses, of the Late Cretaceous sequence in several wells from the Maturin Sub-Basin, Eastern Venezuela. The main objective of this study is to integrate the different faunal and floral assemblages to the sedimentological evolution of the basin using sequential analysis techniques. This technique was applied using mainly terrestrial and marine palynomorphs which were relatively abundant and diverse as compared to the scarcity of foraminifera and nonnofossils. Based on the percentages of abundance and the diversity of the different groups of microfoss it was possible to establish the maximum flooding surfaces and condensation levels which allowed the definition of the possible candidates for the sequence boundaries. On the other hand, the identified bioevents made possible the definition of the chronostratigraphic datums of the sequence under study. The results obtained will contribute to optimize the exploration and development programs of the oil fields in Eastern Venezuela.

Adolescent-Parent Interactions in Relation to Adolescents' Gender and Ego Development Pathway

Family communication patterns were examined in relation to adolescents' gender and ego development pathways using sequential analysis techniques. Thirty-two adolescents from a suburban Boston high school participated in a discussion of moral dilemmas with both their mothers and fathers. The family discussions were scored with the Constraining and Enabling Coding System. During the following 4 years, the adolescents' levels of ego development were assessed with the Loevinger Sentence Completion Test. Sequential and nonsequential analyses revealed variations in family communication patterns associated with adolescent gender, parent gender, and adolescent ego development pathway. Family communication patterns that suggest separation occurred more often with conformist pathway sons and post conformist pathway daughters, while communication patterns that suggest closeness occurred more often with conformist pathway daughters and post conformist pathway sons. The results are discussed in terms of recent work on gender-role socialization and adolescent psychosocial development.

Technique of sequential surface analysis with ISS and AES

AbstractThe development of a new approach is briefly described, which enables Auger electron spectroscopy (AES) and ion scattering spectroscopy (ISS) to be performed sequentially with a commercial‐type Auger microprobe. These sequential AES and ISS measurements were applied to depth composition analysis of the altered layer formed in the surface of AlMg(60 at%) alloy under ion bombardment. A simple analysis has suggested that the ion bom‐bardment forms an altered layer in the surface, which consists of Mg‐rich composition at the top‐most atomic layer, followed by the depletion layers of Mg atoms extending over a few tens of atomic layers deep.

Calcium flux during hemodialysis.

A system of equations has been derived, and examined, to decribed membrane permeability and calcium fluxes within a commonly used hemodialyzer, the Mini-Kiil. By a statistical technique of sequential multiple regression analysis, factors which might influence these variables were tested on data derived from 74 hemodialysis periods in 5 patients. Calcium flux from plasma to dialysate was influenced positively by dialysate calcium concentration and plasma volume flow and negatively by dialysate volume flow. Calcium flux from dialysate to plasma was influenced positively by dialysate calcium concentration and plasma volume flow and negatively by plasma phosphate concentration. Net calcium flux from dialysate to plasma was influenced positively by the calcium gradient (dialysate calcium minus plasma ultrafiltrable calcium) and plasma volume flow and negatively by plasma phosphate concentration (coefficient of multiple correlation =0.970). Because of the magnitude of regression coefficients, manipulations of the dialysate calcium concentration and plasma phosphate concentration were concluded to be the most practical means of adjusting calcium delivery during dialysis.

Dechlorination of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane by Aerobacter aerogenes. I. Metabolic products.

Whole cells or cell-free extracts of Aerobacter aerogenes catalyze the degradation of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) in vitro to at least seven metabolites: 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE); 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD); 1-chloro-2,2-bis(p-chlorophenyl)ethylene (DDMU); 1-chloro-2,2-bis(p-chlorophenyl)ethane (DDMS); unsym-bis(p-chlorophenyl)ethylene (DDNU); 2,2-bis(p-chlorophenyl)acetate (DDA); and 4,4'-dichlorobenzophenone (DBP). The use of metabolic inhibitors together with pH and temperature studies indicated that discrete enzymes are involved. By use of the technique of sequential analysis, the metabolic pathway was shown to be: DDT --> DDD -->DDMU -->DDMS --> DDNU --> DDA --> DBP, or DDT --> DDE. Dechlorination was marginally enhanced by light-activated flavin mononucleotide.

Dechlorination of 1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane by Aerobacter aerogenes

Whole cells or cell-free extracts of Aerobacter aerogenes catalyze the degradation of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) in vitro to at least seven metabolites: 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE); 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD); 1-chloro-2,2-bis(p-chlorophenyl)ethylene (DDMU); 1-chloro-2,2-bis(p-chlorophenyl)ethane (DDMS); unsym-bis(p-chlorophenyl)ethylene (DDNU); 2,2-bis(p-chlorophenyl)acetate (DDA); and 4,4'-dichlorobenzophenone (DBP). The use of metabolic inhibitors together with pH and temperature studies indicated that discrete enzymes are involved. By use of the technique of sequential analysis, the metabolic pathway was shown to be: DDT --> DDD -->DDMU -->DDMS --> DDNU --> DDA --> DBP, or DDT --> DDE. Dechlorination was marginally enhanced by light-activated flavin mononucleotide.

Hailfall Data from a Fixed Network for the Evaluation of a Hail Modification Experiment

Haifall data collected from a fixed network in northeastern Colorado during three seasons (1960–62) included the estimated impact energy, duration of hailfall, most common stone size, maximum stone size, and number of stones per square inch. These basic data,X, along with the transformations, lnN, √X, 3√X, and 1/X were analyzed by computer methods to determine which parameters could be used in a statistical analysis of hail suppression experiment. The gamma distribution function was fitted to the hailfall data by the method of maximum likelihood. A chi-square goodness of fit test was applied to the data, and one transformation was tested using a sequential analysis technique. All parameters except impact energy and number of hailstones per square inch were eliminated from the statistical analysis because of bias, non-homogeneity, or sparsity of samples. Transformations which produced the minimum mean coefficient of variation were logarithm of impact energy (InE) and square root of the number of stones per square inch (√N1 − 6). It was determined that a target-control analysis was not feasible for the analysis of hail suppression experiment. A period of 3 to 5 years is believed necessary to detect changes of 10 to 25 per cent in the hail parameters. The gamma distribution function fitted only the √N1 − 6 data. From the results it was concluded that a sequential analysis test alone could not adequately evaluate the effectiveness of a hall modification experiment.

Some Empirical Aspects of the Sequential Analysis Technique as Applied to an Achievement Examination

With the presentation of the early paper 1 on sequential analysis by Dr. Wald, a new frontier in modern statistics was achieved. Prior to those writings it had been shown by Professor R. A. Fisher that the proper place for determ ining the size of sample needed in an experiment was in the planning of the experiment itself. That is, before the experiment was executed. It is well known that previous to Fisher's work, most thought about the proper sample size took place after the experiment was run. We note to day the metamorphosis of the determination of sample size, for with Wald's writing we see that under certain circumstances n is no longer to be regarded as a fixed quantity but as a ran dom variable, and that the designation of the proper sample size is made by the experiment itself. It is in the sense that the statistical cog itation about n becomes a part of the experi ment rather than a prelude or post-mortem of it, that the marvel of the sequential procedure is noted. The use of sequential analysis in educational problems has been undertaken at least by two authors. 2, 3 Dr. H. M. Walker has made a con tribution in the field of item analysis, and Dr. Cowden used sequential analysis in administer ing an examination.