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PubMed1990

Personality variables as mediators and moderators of family history risk for alcoholism: conceptual and methodological issues.

Recently there has been great interest in possible mediators and moderators of family history risk for alcoholism. However, previous studies have failed to employ appropriate designs and data analytic strategies to identify moderators and mediators. This article uses a large data set to illustrate such analyses. In the current data, both presumed personality risk and dispositional self-awareness were found to play moderator (rather than mediator) roles. The conceptual, methodological and data analytic implications of the mediator-moderator distinction are discussed.

Adolescent↗
PubMed2001

The need for mixed-effects modeling with population dichotomous data.

Over the past 25 years sophisticated data analytic techniques have been developed which can lead to improved analyses, but at additional computational cost. In particular, this applies to the approach where interindividual random effects are included in a data analytic model for population pharmacokinetic data, which can often lead to substantially improved estimates of fixed-effect parameters. However, there are also commonly occurring situations, notably with some types of pharmacodynamic data, where such improvement is not realized. This study simulates some simple population dichotomous data, and secondarily, some related continuous data. These data are analyzed using both mixed-effect (ME) models that include interindividual random effects and naive (NA) models that do not include interindividual random effects, and it is seen that use of an ME model does not inevitably lead to gains over use of an NA model. In fact, using maximum likelihood estimation with both types of models, the root mean square estimation errors for fixed effect parameters can actually be larger with an ME model than with the corresponding NA model. Using a form of restricted maximum likelihood estimation with the ME model, the two types of models yield root mean square errors which are comparable, but which still do not suggest that there is always marked advantage in using the ME model.

Humans↗
PubMed2003

CytometryML, an XML format based on DICOM and FCS for analytical cytology data.

BACKGROUND: Flow Cytometry Standard (FCS) was initially created to standardize the software researchers use to analyze, transmit, and store data produced by flow cytometers and sorters. Because of the clinical utility of flow cytometry, it is necessary to have a standard consistent with the requirements of medical regulatory agencies. METHODS: We extended the existing mapping of FCS to the Digital Imaging and Communications in Medicine (DICOM) standard to include list-mode data produced by flow cytometry, laser scanning cytometry, and microscopic image cytometry. FCS list-mode was mapped to the DICOM Waveform Information Object. We created a collection of Extensible Markup Language (XML) schemas to express the DICOM analytical cytologic text-based data types except for large binary objects. We also developed a cytometry markup language, CytometryML, in an open environment subject to continuous peer review. RESULTS: The feasibility of expressing the data contained in FCS, including list-mode in DICOM, was demonstrated; and a preliminary mapping for list-mode data in the form of XML schemas and documents was completed. DICOM permitted the creation of indices that can be used to rapidly locate in a list-mode file the cells that are members of a subset. DICOM and its coding schemes for other medical standards can be represented by XML schemas, which can be combined with other relevant XML applications, such as Mathematical Markup Language (MathML). CONCLUSIONS: The use of XML format based on DICOM for analytical cytology met most of the previously specified requirements and appears capable of meeting the others; therefore, the present FCS should be retired and replaced by an open, XML-based, standard CytometryML.

Computer Communication Networks↗
PubMed2004

Study of traffic pollution by metals in Seville (Spain) by physical and chemical speciation methods.

Eighty-three samples of atmospheric particles were collected at a representative traffic site in the Mediterranean city of Seville during a period of one year. Urban particles were collected on quartz filters with a high-volume sampler coupled with a cascade impactor which separates particles into six size ranges: >10, 10-4.9, 4.9-2.7, 2.7-1.3, 1.3-0.6, and <0.6 microm. The total metal content, its distribution by size (physical speciation), and the concentrations of different chemical forms (chemical speciation) in particles less than 0.6 microm were determined. The chemical speciation scheme furnished four fractions: soluble and exchangeable metals; carbonates, oxides, and reducible metals; oxidisable and sulfidic metals bound to organic matter; and residual metals. The samples were analysed by ICP-OES for Pb, Ni, Cd, S, Fe, Zn, Cu, Ba, Mn, and V. Gaseous pollutants, traffic intensities, and primary meteorological data provided by the atmospheric and traffic networks were statistically related to the analytical data. Analytical and statistical results from physical and chemical speciation singled out Ba as a valid tracer of vehicular traffic, instead of Pb, in cities with high traffic density. Another important relationship was found between Pb and Cu. Physical speciation of lead showed that the major risk for health was from fine particles less than 2.7 microm, because particles between 2.7 and 0.6 microm were the size fractions of the total suspended particles with the major mass abundance of lead (mainly particles between 2.7 and 1.3 microm) and because particles less than 0.6 microm were the fraction of airborne particles most abundant in the urban air. Chemical speciation results showed that special attention must be taken with Ni and Cd concentrations, because of their high potential bioavailability, mainly a result of the high solubility of the chemical forms of Ni in the finest particles.

Air Pollutants↗
PubMed1997

Air pollution and the deterioration of historic monuments.

The results of air pollution surveys conducted at two sites in the historic center of Rome and at two sites in Latium are summarized and illustrated. The objective of our study is to identify a link between the analytical data and brightness measurements of outdoor stone monuments in the selected areas. The analytical data coincide well with the characteristics of the sites with heavy traffic (Rome and Villa d'Este in Tivoli) when compared with the "zero level exposure" of the Villa Adriana.

Air Pollution↗
PubMed1991

Chiral drugs: an industrial analytical perspective.

In the pharmaceutical industry, chiral drug candidates introduce a unique set of challenges to all disciplines involved in the drug development process. For the analytical chemist in particular, the generation of relevant information about a variety of stereoisomeric issues is necessary. Chiral drug candidates, whether a single isomer or a mixture of isomers, require more analytical information than achiral drug candidates. This information can be derived from enantioselective spectroscopic and chromatographic techniques. Chiral analytical methods require proper development and validation to ensure accurate results. Issues related to method development and validation for complete stereochemical characterization are discussed, with primary emphasis on the generation of analytical data required for the registration of a chiral drug candidate. The presentation of pertinent analytical data depends on an awareness of the problems encountered during the development process and the appropriate use of methodology for the determination of stereoisomeric purity.

Animals↗
PubMed1998

Quality assurance in veterinary diagnostic laboratories.

The authors discuss the responsibility of veterinary diagnostic laboratories as suppliers of analytical data for tests on animals and animal products. The guarantee of the quality of analytical data is a basic quality requirement for veterinary certification. It is therefore important for the laboratory to adopt operational quality assurance standards which are recognised internationally. The management and quality assurance criteria contained in the International Standardisation Organisation/International Electrotechnical Commission Guide 25, or in directives or guidelines established by international organisations such as the Office International des Epizooties and the Codex Alimentarius of the Food and Agriculture Organisation, are reviewed. These documents provide procedures for adopting the principles of quality assurance in order to acquire the recognition of competence to execute the laboratory tests required for national and international veterinary certification.

Animals↗
PubMed1985

Toxicity modeling and prediction with pattern recognition.

Empirical models can be constructed relating the change in toxicity to the change in chemical structure for series of similar compounds or mixtures. The first step is to translate the variation in structure to quantitative numbers. This gives a data table, a data matrix denoted by X, which then is analyzed. The same type of the models can be used to relate the variation of in vivo data to the variation of a battery of in vitro tests. A single data analytical model cannot be applied to a set of compounds of diverse chemical structure. For such data sets, separate models must be developed for each subgroup of compounds. The data analytical problem then partly is one of classification, pattern recognition (PARC). The assumption of structural and biological similarity within each subset of modeled compounds is then essential for empirical models to apply. PARC is often used to classify compounds as active (toxic) or inactive. The data structure is then often asymmetric which puts special demands on the data analysis, making the traditional PARC methods inapplicable. Depending on the desired information from the data analysis and on the type of available data, four levels of PARC can be distinguished: (I) the data X are used to develop rules for classifying future compounds into one of the classes represented in X; (II) same as I, but the possibility of future compounds belonging to "unknown" classes not represented in X is taken into account; (III) same as II, plus the quantitative prediction of one activity variable (here toxicity) in some classes; (IV) same as III, but several quantitative activity (toxicity) variables are predicted.

Mathematics↗
PubMed2004

Application of inorganic element ratios to chemometrics for determination of the geographic origin of welsh onions.

The composition of concentration ratios of 19 inorganic elements to Mg (hereinafter referred to as 19-element/Mg composition) was applied to chemometric techniques to determine the geographic origin (Japan or China) of Welsh onions (Allium fistulosum L.). Using a composition of element ratios has the advantage of simplified sample preparation, and it was possible to determine the geographic origin of a Welsh onion within 2 days. The classical technique based on 20 element concentrations was also used along with the new simpler one based on 19 elements/Mg in order to validate the new technique. Twenty elements, Na, P, K, Ca, Mg, Mn, Fe, Cu, Zn, Sr, Ba, Co, Ni, Rb, Mo, Cd, Cs, La, Ce, and Tl, in 244 Welsh onion samples were analyzed by flame atomic absorption spectroscopy, inductively coupled plasma atomic emission spectrometry, and inductively coupled plasma mass spectrometry. Linear discriminant analysis (LDA) on 20-element concentrations and 19-element/Mg composition was applied to these analytical data, and soft independent modeling of class analogy (SIMCA) on 19-element/Mg composition was applied to these analytical data. The results showed that techniques based on 19-element/Mg composition were effective. LDA, based on 19-element/Mg composition for classification of samples from Japan and from Shandong, Shanghai, and Fujian in China, classified 101 samples used for modeling 97% correctly and predicted another 119 samples excluding 24 nonauthentic samples 93% correctly. In discriminations by 10 times of SIMCA based on 19-element/Mg composition modeled using 101 samples, 220 samples from known production areas including samples used for modeling and excluding 24 nonauthentic samples were predicted 92% correctly.

China↗
PubMed2006

Validation of new methods.

Reliable analytical data are a prerequisite for correct interpretation of toxicological findings in the evaluation of scientific studies, as well as in daily routine work. Unreliable analytical data might not only be contested in court, but could also lead to unjustified legal consequences for the defendant or to wrong treatment of the patient. Therefore, new analytical methods to be used in forensic and/or clinical toxicology require careful method development and thorough validation of the final method. This is especially true in the context of quality management and accreditation, which have become matters of increasing relevance in analytical toxicology in recent years. In this paper, important considerations in analytical method validation will be discussed which may be used as guidance by scientists wishing to develop and validate analytical methods.

Data Interpretation, Statistical↗
PubMed1991

Integrated approach for designing medical decision support systems with knowledge extracted from clinical databases by statistical methods.

In clinical research data is often studied by a particular method without previous analysis of quality or semantic contents which could link clinical database and data analytical (e.g. statistical) procedures. In order to avoid bias caused by this situation, we propose that the analysis of medical data should be divided into two main steps. In the first one we concentrate on conducting the quality, semantic and structure analyses. In the second step our aim is to build an appropriate dictionary of data analysis methods for further knowledge extraction. Methods like robust statistical techniques, procedures for mixed continuous and discrete data, fuzzy linguistic approach, machine learning and neural networks can be included. The results may be evaluated both using test samples and applying other relevant data-analytical techniques to the particular problem under the study.

Artificial Intelligence↗
PubMed2006

Increasing conclusiveness of metabonomic studies by chem-informatic preprocessing of capillary electrophoretic data on urinary nucleoside profiles.

Nowadays, bioinformatics offers advanced tools and procedures of data mining aimed at finding consistent patterns or systematic relationships between variables. Numerous metabolites concentrations can readily be determined in a given biological system by high-throughput analytical methods. However, such row analytical data comprise noninformative components due to many disturbances normally occurring in analysis of biological samples. To eliminate those unwanted original analytical data components advanced chemometric data preprocessing methods might be of help. Here, such methods are applied to electrophoretic nucleoside profiles in urine samples of cancer patients and healthy volunteers. The electrophoretic nucleoside profiles were obtained under following conditions: 100 mM borate, 72.5 mM phosphate, 160 mM SDS, pH 6.7; 25 kV voltage, 30 degrees C temperature; untreated fused silica capillary 70 cm effective length, 50 microm I.D. Different most advanced preprocessing tools were applied for baseline correction, denoising and alignment of electrophoretic data. That approach was compared to standard procedure of electrophoretic peak integration. The best results of preprocessing were obtained after application of the so-called correlation optimized warping (COW) to align the data. The principal component analysis (PCA) of preprocessed data provides a clearly better consistency of the nucleoside electrophoretic profiles with health status of subjects than PCA of peak areas of original data (without preprocessing).

Algorithms↗
PubMedDate not supplied

[Evaluating hospital appropriateness with different tools: administrative data versus analytic review].

PRUO, a modified version of AEP, is a widely used clinical-based tool to evaluate hospital appropriateness in Italy. We developed the APPRO method for assessing organizational appropriateness using administrative data. APPRO estimates the amount of inappropriate hospitalisation, giving consideration to severity of illness through APR-DRG classification system. The aims of the study were to: measure the agreement between evaluators using PRUO; investigate the relation between APR-DRG severity subgroups and PRUO assessment; asses the validity of APPRO method comparing its performance to PRUO results. We selected 361 hospital episodes assigned to DRG 39 ("lens procedures with or without vitrectomy") and 242 hospital episodes assigned to DRG 183 ("miscellaneous of digestive disorders, age > 17") from three hospitals in 2000. Clinical records were independently evaluated by two pairs of physicians using PRUO. Proportions of inappropriate episodes by hospital and DRG were also estimated through APPRO using data from Lazio regional hospital information system. The agreement between the two pairs of evaluators was high (k=0.93; p<0.0001). We observed no statistically significant association between APR-DRG severity subgroups and inappropriate hospitalisation found by PRUO. APPRO underestimates rates of inappropriate hospitalisation compared to PRUO. It depends on the different characteristics of the tools and particularly on the caution of APPRO in performing the evaluation using routine data.

Diagnosis-Related Groups↗
PubMed1990

Psychotherapy process research: progress, dilemmas, and future directions.

The first several decades of psychotherapy process research have produced advances in measure development and substantive findings of process-outcome relations. A recent paradigm shift toward sequentially patterned, significant change episodes is described, emphasizing segmentation of process by meaningful patterns wherever they occur. Theoretical, psychometric, and data analytic dilemma are reviewed. Strategies are offered that may enhance future research efforts. These include greater attention to construct validity of measures, the relation of process to phase-specific outcome criteria, and the continuing development of multivariate data analytic strategies that take into account Patient X Treatment interactions as well as the sequential dependency of process data. The development of a national archive of significant change events is recommended to advance modeling of the change process, segmentation, construct validation of measures, integration of qualitative and quantitative approaches, and development of a cross-theoretical language for therapy process.

Follow-Up Studies↗
PubMed1993

Analytical and biological data of banked samples--a requirement to interpret accumulation and leaching of pollutants in biological specimens.

The accumulation of organic and inorganic pollutants in biological specimens depends, in many cases, not only on the atmospheric deposition or immission and contamination of the biotop, but also on the dynamic properties of the indicator. Thus the analytical data assume properties of process variables. In order to compare them in relation to space and time, it is often practical to refer them to defined conditions of the indicator (stationary phases, time cycles of low dynamics). If the accumulation varies consistently under identical conditions of contamination and if clear functional relations exist to the features of the indicator, for instance age, weight or ecological processes, it is necessary to normalize the analytical data, i.e. to refer them to a condition of the indicator which is defined meaningfully with regard to the ecology. Interactions with other inputs of substances may result in a differentiation of accumulation and leaching processes which is more or less specific for each element. Such knowledge is important for specifying the standard operation procedures and the evaluation as well as interpretation of analytic data, in particular, in the clarification of the ecotoxicological relations between the pollutant accumulation and the reaction of populations and ecosystems.

Animals↗
PubMed2002

Recent developments in food characterization and adulteration detection: technique-oriented perspectives.

This review covers mainly publications that appeared in Analytical Abstracts (Royal Society of Chemistry) from January 1990 to February 2001. The number of publications on this topic continues to grow, and during the past three years (1998-2000) about 150 reviews and/or overviews have been published in the area of food. Numerous techniques and food matrices or chemical components are presented and discussed in these reviews. The present review is intentionally limited to eight techniques or classes of techniques and intends to be a "technique by technique" presentation of "what was used" or "what is used" to characterize food products and to detect their possible adulteration. The present review focuses on the following techniques: microscopic analysis; HPLC; GC, GC-(MS, FTIR); UV-visible spectrophotometry; AAS/AES, ICP-(AES, MS); IRMS, GC-IRMS, GC-C-IRMS; DSC; IR, mid-IR, and NMR (202 references). Emphasis is placed as much as possible on chemometrical treatment of analytical data, which are commonly used to achieve the final objective, either food characterization or adulteration detection. Finally, a brief description is given of the new generation of analytical systems that combine powerful analytical techniques and powerful computer software for a best extraction of the information from analytical data.

Calorimetry, Differential Scanning↗
PubMed2000

Estimation of structural wave numbers from spatially sparse response measurements.

A method is presented for estimating the complex wave numbers and amplitudes of waves that propagate in damped structures, such as beams, plates, and shells. The analytical basis of the method is a wave field that approximates response measurements in an aperture where no excitations are applied. At each frequency, the method iteratively adjusts wave numbers to best approximate response measurements, using wave numbers at neighboring frequencies as initial estimates in the search. In comparison to existing methods, the method generally requires far fewer measurement locations and does not require evenly spaced locations. The number of locations required by the method scales with the number of waves that propagate in the structure, whereas the number of locations required by existing methods scales with the minimum wavelength. In addition, the method allows convenient inclusion of the analytic relationships between wave numbers that exist for flexural vibrations of beams and plates. Advantages of the method are illustrated by an example in which a beam is excited by a transverse force at one end. Using analytic data and experimental measurements, the method produces a wave field that matches response measurements to within 1 percent. One interesting feature of the new method is that, when applied to analytic data, it supplies more robust wave number estimates using responses at unevenly spaced locations.

Acoustics↗