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Results for “Principal Component Analysis”

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PubMed2004

[Relationship of occupational injuries with social and economic factors].

OBJECTIVE: To explore the relationship of occupational injuries with social and economic factors in chemical industry during 2000.01 - 2001.12. METHOD: 1:2 paired case-control study, univariable logistic regression analysis, principal component analysis, and multiple logistic regression analysis were used in this study. RESULTS: Univariable analysis showed that occupational injuries had significant relationship with age, sex, education, employment pattern, technology, workplace, work changing, wage, family income, enterprise scale, enterprise proprietorship, projective device, operation rules, and training rules of work safety. The extracted four principal components (PC(1), PC(2), PC(3) and PC(4), ranked by contribution) gave good expressions to the initial 11 variables. The cumulative proportion of the four principal components reached 77.36%. PC(1) was the indicative factor of occupational injuries, which represented 46.69% information of initial variables. PC(2) was the kinetic factor of occupational injuries. PC(3) was the stable factor of occupational injuries. PC(4) was the sex factor of occupational injuries. The results of multiple conditional logistic regression analysis showed that occupational injuries had statistically significant relationship with PC(1) and PC(2). Among the initial variables, sex, employment pattern, income, scale of enterprise, and property of enterprise were more prominent. CONCLUSION: Occupational injuries are related with multiple social and economic factors, which often interact on each other. The prevention and control of occupational injuries should require a comprehensive approach, including training and education of work safety, improving workers' consciousness of self-protection, and enhancing proprietors' consciousness of work safety.

Accidents, Occupational↗

PubMed2005

Recipes for the linear analysis of EEG.

In this paper, we describe a simple set of "recipes" for the analysis of high spatial density EEG. We focus on a linear integration of multiple channels for extracting individual components without making any spatial or anatomical modeling assumptions, instead requiring particular statistical properties such as maximum difference, maximum power, or statistical independence. We demonstrate how corresponding algorithms, for example, linear discriminant analysis, principal component analysis and independent component analysis, can be used to remove eye-motion artifacts, extract strong evoked responses, and decompose temporally overlapping components. The general approach is shown to be consistent with the underlying physics of EEG, which specifies a linear mixing model of the underlying neural and non-neural current sources.

Algorithms↗

PubMed2006

Assessing heavy metal sources in agricultural soils of an European Mediterranean area by multivariate analysis.

According to the European Thematic Strategy for Soil Protection, the characterization of the content and source of heavy metals in soils are necessary to establish quality standards on a regional level that allow the detection of sampling sites affected by pollution. In relation to this, the surface horizons of 54 agricultural soils under vegetable crops in the Alicante province (Spain), a representative area of the European Mediterranean region, were sampled to determine the content of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn. Analytical determinations were performed by atomic absorption spectroscopy after microwave sample digestion in acid solution. Results indicated that heavy metal levels were similar to those reported by authors working on agricultural soils from other parts of the Mediterranean region, with the exception of Cu and Pb in some samples. Multivariate analysis (principal component analysis and cluster analysis) was performed to identify a common source for heavy metals. Moreover, soil properties were determined in order to characterize agricultural soils and to analyze relationships between heavy metal contents and soil properties. The content of Co, Cr, Fe, Mn, Ni and Zn were associated with parent rocks and corresponded to the first principal component called the lithogenic component. A significant correlation was found between lithogenic metals and some soil properties such as soil organic matter, clay content, and carbonates, indicating an important interaction among them. On the other hand, elements such as Cd, Cu and Pb were related to anthropic activities and comprised the second (Cu and Pb) and third principal components (Cd), designated the anthropogenic components. Generally, Cd, Cu and Pb showed a lower correlation with soil properties due to the fact that they remain in available forms in these agricultural soils. Taking into account these results and other achieved in other parts of the European Mediterranean region, it can be concluded that soil quality standards are highly needed to declare soils affected by human induced pollution. This is particularly relevant for anthropogenic metals (Cd, Cu and Pb, and in some areas also Zn). Further research in other agricultural areas of the region would improve the basis for proposing such soil quality standards.

Agriculture↗

PubMed1990

Structure of ischemic heart disease risk factors in the North Khanty population of western Siberia.

The relationships between serum lipids, blood pressures, anthropometric traits, age, and ischemic changes of the electrocardiogram (ECG) in the North Khanty population were studied. To this end, eight morphophysiological variables--presumably risk factors for ischemic heart disease--have been subjected to a principal components analysis. Two principal components were extracted. The first revealed age dependency of the traits not associated with ischemic changes of myocardium in both sexes. A comparative analysis of the second component has shown that the chosen traits correlated with ischemic heart disease in males but not in females. Interpretation is given of the components obtained.

Age Factors↗

PubMed1994

Alcohol dependence and cue reactivity.

A group of 35 severely dependent male alcoholic patients undergoing cue exposure treatment were studied. Thirty-one subjects had complete data and their physiological and subjective responses to drink cues on the first day of the cue exposure program were subjected to a principal components analysis. The principal component loadings were then used to construct a single measure of responsivity and this responsivity measure was found to correlate significantly with Severity of Alcohol Dependence Questionnaire (SADQ) scores. Further analysis of the relationship between responsivity and the subscales of the SADQ showed that the experience of affective withdrawal symptoms, craving for alcohol and drinking to relieve withdrawal symptoms were the most strongly correlated with responsivity.

Adult↗

PubMed2000

Are baseline frequencies of SCEs, CAs, and MN in human lymphocytes related to hematological values?

In the present study, the correlation among several hematic values and the baseline frequencies of sister chromatid exchanges (SCEs), chromosome aberrations (CAs), and micronucleus (MN) were evaluated in human peripheral blood lymphocytes from a group of 1429 volunteers. Donors were selected to be representative of the general population of people living in the city of Pisa (Italy). By the use of the principal component analysis (PCA), principal components (PCs) were extracted from the complex pattern of correlations intrinsic in the hematic values (for example such as those among hemoglobin content, hematocrit, and erythrocyte count), and were tested for correlation on SCE, CA and MN frequencies. The seven PCs extracted (among 20 hematic values) were either positively or negatively correlated with the three cytogenetic endpoints. However, after correction by independent confounding factors (such as the age), with the use of the coefficient of partial correlation (CPC) analysis, only one PC significantly held the correlation with MN frequencies. This PC had the main contribution from the correlation between the concentration of potassium and the activity of alkaline phosphatase. These variables are known to be markers for bone (calcium) metabolism and are negatively correlated with MN frequencies. Because MN can arise from aneuploidy, the hematic concentrations of calcium may be important for stabilizing the mitotic process in stimulated lymphocytes. Finally, our study shows that the analysis of the hematic values adds very little information and removes a meaningless part of variance of the total variability observed for SCEs, CAs and MN.

Adult↗

PubMed2003

Feasibility study on the use of visible and near-infrared spectroscopy together with chemometrics to discriminate between commercial white wines of different varietal origins.

The use of visible (vis) and near-infrared spectroscopy (NIR) was explored as a tool to discriminate between samples of Australian commercial white wines of different varietal origins (Chardonnay and Riesling). Discriminant models were developed using principal component analysis (PCA), principal component regression (PCR), and discriminant partial least-squares (DPLS) regression. The samples were randomly split into two sets, one used as a calibration set (n = 136) and the remaining samples as a validation set (n = 133). When used to predict the variety of the validation set samples, the DPLS models correctly classified 100% of Riesling and up to 96% of Chardonnay wines. These results showed that vis-NIR might be a suitable and alternative technology that can be easily implemented by the wine industry to discriminate Riesling and Chardonnay commercial wine varieties. However, the relatively limited number of samples and varieties involved in the present work suggests caution in extending the potential of such a technique to other wine varieties.

Discriminant Analysis↗

PubMed1997

Seasonal fluctuations in the cervical smear detection rates for (pre)malignant changes and for infections.

The detection of diseases can exhibit seasonal fluctuations. This can be studied in cervical smears. Over a 9-year observation span (January 1983-January 1992) a series of 504,093 cervical smears obtained from a routine cytology laboratory in The Netherlands were examined for infections (monilia, trichomonas, actinomyces, human papilloma virus [HPV], chlamydia, and herpes) as well as for mild, moderate, and severe dysplasias, carcinoma in situ, and squamous carcinoma. Statistical analysis (principal component analysis) demonstrates clear seasonal rhythms in the detection of infections as well as in precursor lesions. These findings suggest that we are dealing with "true" detection rhythms. For the detection of (pre)malignancy and HPV, yearly fluctuations in women being screened might be the explanation for our observations.

Actinomycosis↗

PubMed2000

Resampling as a cluster validation technique in fMRI.

Exploratory, data-driven analysis approaches such as cluster analysis, principal component analysis, independent component analysis, or neural network-based techniques are complementary to hypothesis-led methods. They may be considered as hypothesis generating methods. The representative time courses they produce may be viewed as alternative hypotheses to the null hypothesis, i.e., "no activation." We present here a resampling technique to validate the results of exploratory fuzzy clustering analysis. In this case an alternative hypothesis is represented by a cluster centroid. For both simulated and in vivo functional magnetic resonance imaging data, we show that by permutation-based resampling, statistical significance may be computed for each voxel belonging to a cluster of interest without parametric distributional assumptions.

Brain↗

PubMed2000

Foaming characteristics of chemical and enzymatic hydrolysates of bovine beta-lactoglobulin.

The foaming properties of bovine beta-lactoglobulin (BLG), BNPS-skatole (2-(2'-nitrophenylsulfenyl)-3-methyl-3'-bromoindolenine) (BNPS), trypsin (T) and pepsin in 25, 30 and 40% ethanol (P25, P30, P40) hydrolysates were investigated in the 0.2 to 1 mg/ml range. Foaming capacity and foam stability were assessed in terms of drained liquid volume and foam volume. Foam texture was analyzed from video images obtained during foam decay. The foaming capacity of BNPS, P30 and P40 was similar to that of BLG and greater than that of T or P25. All hydrolysates except BNPS were less stable than BLG at all concentrations tested. This result was insured by texture analysis. Principal component analysis confirmed the distribution of the samples into three groups based on their increasing stability: (i): P25, (ii): P30 and P40, and (iii): BLG and BNPS. Tryptic hydrolysate had the poorest foaming properties. The results are considered in relation to the molecular characteristics of the peptides, particularly their size and hydrophobicity.

Animals↗

PubMed2004

Geographic distribution of environmental factors influencing human skin coloration.

Skin coloration in indigenous peoples is strongly related to levels of ultraviolet radiation (UVR). In this study, the relationships of skin reflectance to seasonal UVR levels and other environmental variables were investigated, with the aim of determining which variables contributed most significantly to skin reflectance. The UVR data recorded by satellite were combined with environmental variables and data on human skin reflectance in a geographic information system (GIS). These were then analyzed visually and statistically through exploratory data analysis, correlation analysis, principal components analysis, least-squares regression analysis, and nonlinear techniques. The main finding of this study was that the evolution of skin reflectance could be almost fully modeled as a linear effect of UVR in the autumn alone. This linear model needs only minor modification, by the introduction of terms for the maximum amount of UVR, and for summer precipitation and winter precipitation, to account for almost all the variation in skin reflectance. A further significant finding was that the effect of summer UVR seems to reach a threshold beyond which further adaptation is difficult.

Environmental Exposure↗

PubMed2003

Cranial allometry, phylogeography, and systematics of large-bodied papionins (primates: Cercopithecinae) inferred from geometric morphometric analysis of landmark data.

The cranial morphology of the African Old World monkeys Mandrillus, Papio, and Theropithecus (i.e., baboons) has been the subject of a number of studies investigating their systematic relationships, patterns of scaling, and growth. In this study, we use landmark-based geometric morphometrics and multivariate analysis to assess the effects of size, sex, taxonomy, and geographic location on cranial shape. Forty-five landmarks were digitized in three dimensions on 452 baboon crania and subjected to generalized Procrustes analysis (GPA), which standardizes geometric size but leaves scaling-based shape differences in the data. The resulting shape coordinates were submitted to regression analysis, principal components analysis (PCA), partial least-squares (PLS) analysis, and various clustering techniques. Scaling (shape differences correlated with size) was the largest single factor explaining cranial shape variation. For instance, most (but not all) of the shape differences between the sexes were explained by size dimorphism. However, central tendencies of shape clearly varied by taxon (both specific and subspecific) even after variations in size and sex were adjusted out. Within Papio, about 60% of the size- and sex-adjusted shape variations were explained by the geographic coordinates of the specimen's provenance, revealing a stepped cline in cranial morphology, with the greatest separation between northern and southern populations. Based on evidence from genetic studies, and the presence of at least two major hybrid/interbreeding zones, we interpret the phylogeographic pattern of cranial variation as indicating that these populations are best ranked as subspecies of a single species, rather than as two or more distinct biological species. This objective approach can be applied to other vertebrate species or species groups to help determine the taxonomic rank of problematic taxa.

Africa↗

PubMed2006

Use of FTIR spectroscopy to distinguish between capsular types and capsular quantities in Streptococcus pneumoniae.

Fourier transform infrared (FTIR) spectroscopy has shown remarkable ability in distinguishing between bacterial species and identifying bacterial colony structures, when used in tandem with methods such as cluster analysis, principal component analysis, or linear discriminant analysis. The present work was aimed to evaluate the potential of FTIR-microscopy (FTIR-MSP) to distinguish between different serotypes and capsular quantities of Streptococcus pneumoniae. In general, the results obtained have consistently proven that the spectral information at the region 900-1,185 cm(-1) was sufficient to distinguish between various pneumococcal serotypes. Moreover, the method was able to differentiate between S. pneumoniae phase variants on the basis of their relative carbohydrate content. The unsupervised cluster analysis of the samples showed differences, not only in the carbohydrate content, but also in the region 1,350-1,480 cm(-1), which is dominated by absorptions due to lipids and phospholipids. This approach proved to be useful for the distinction between S. pneumoniae serotypes and between phase variants, which were shown to acquire different pathogenic capacity.

Bacterial Capsules↗

PubMed1977

Pattern recognition II: Investigation of structure--activity relationships.

A simple form of pattern recognition is successfully used to classify a set of structurally diverse therapeutic agents. By using only organic structural information, the major pharmacological classes present were correctly identified and the pharmacologically unrelated compounds were separated out. One technique of factor analysis--principal component analysis--is shown to be readily adaptable in preprocessing the data. Simple graphical representation of the results enables their direct interpretation.

Chemistry, Pharmaceutical↗

PubMed2026

Validation of a Turkish Translation of the Stress in Emergency Healthcare Professionals: The Stress Factors and Manifestations Scale.

AIM: The primary duties of emergency healthcare professionals (EHPs) are to provide emergency patient care to acutely ill and injured individuals. Due to the nature of their work, EHPs operate under constant stress, often requiring rapid decision-making, swift action, and the delivery of necessary medical care in life-or-death situations, sometimes under inadequately safe conditions. Therefore, the aim of this study is to determine the validity and reliability of the Emergency Healthcare Professional Stress Factors and Symptoms (SEHP:SFMS) Scale in Turkish for identifying stress factors and symptoms in emergency medical care professionals providing emergency patient care services. DESIGN: A methodological study design was used in this study. METHODS: The study was conducted with the participation of 211 EHPs from employees working in emergency care institutions affiliated with the Muğla Provincial Health Directorate between November 2023 and June 2024. Data were collected via a face-to-face survey. Data were analysed using Lawshe content validity ratio, Kaiser-Meyer-Olkin coefficient, Bartlett test, exploratory factor analysis, principal component analysis, Varimax factor rotation method, confirmatory factor analysis, Cronbach's α internal consistency coefficient, convergent validity, discriminant validity, test-retest, and Spearman correlation coefficient tests. RESULTS: The linguistic translation and cultural adaptation of the SEHP:SFMS showed strong performance. The scope validity index of the scale is 0.83. The item-total correlation values of the scale were found to be between 0.486 and 0.794, and the factor loadings were between 0.474 and 0.816. Confirmatory factor analysis fit indices: χ2 = 248.727; df = 101; n = 211; p = 0.000; χ2/df = 2.463; RMSEA = 0.083; CFI = 0.914, SRMR = 0.052, which was found to be compatible and acceptable with the proposed 3-factor model. The Cronbach's α reliability coefficient of the scale was 0.931, and the total variance was 61.97%. CONCLUSIONS: SEHP:SFMS is a valid and reliable tool to assess stress factors and symptoms of Turkish emergency healthcare professionals. Its use improves the quality of emergency care. PATIENT OR PUBLIC CONTRIBUTION: These study findings have been used to create a tool with Turkish validity and reliability that allows for the examination of stress factors among healthcare professionals working in emergency and critical services. Identifying and reducing stress factors among healthcare professionals is crucial for the delivery of quality healthcare services. It can also be used to develop targeted interventions and ongoing strategies to facilitate improved clinical supervision and mentoring. IMPLICATION FOR NURSING PRACTICE: Nurses in emergency departments, which are among the most stressful, dynamic, intense, life-saving, and critical environments in healthcare institutions, and where life-saving treatment is administered, are at high risk of experiencing psychological trauma. Trauma experienced in the work environment is a significant problem for nursing. The consequences of trauma negatively affect nurses and institutions. Studies show that post-traumatic stress, anxiety, depression, and burnout are commonly observed in emergency department nurses. In this sense, understanding the stress and stress factors experienced by nurses can guide future interventions. The results of this study are considered important in making visible the stress and stress factors experienced by nurses in the emergency department, and also in guiding managers and nurses working in this field in terms of preventive and protective measures.

Humans↗

PubMed1996

Application of multivariate curve resolution to voltammetric data. II. Study of metal-binding properties of the peptides.

The complexation of Cd2+ by glutathione (GSH), in 0.13 m borate buffer at pH 9.5, was studied by differential pulse polarography (DPP) and multivariate curve resolution. The Cd-GSH system has been chosen as a model to check the possibilities of this new polarographic approach to the study of metal ion complexation by peptides. Experimental data obtained by DPP for different Cd2+-to-GSH concentration ratios have been analyzed by a procedure which consists of using several chemometrical techniques based on factor analysis: principal component analysis, evolving factor analysis, and multivariate curve resolution with alternating least-squares (ALS) optimization. The use of different constraints during the ALS optimization process, such as nonnegativity and unimodality constraints, yields the optimal sought solution from a chemical point of view. In the present work, a new constraint has been implemented during ALS optimization to take into account the expected peak-shaped signal of DPP. This data treatment allows us to detect simultaneously the formation of 1:1 and 1:2 Cd:GSH complexes which were very difficult to detect by univariate analysis of DPP data. It is concluded that the described multivariate curve resolution method could be a reliable tool for studying metal-binding properties of peptides.

Cadmium↗

PubMed1994

A 3D QSAR approach to the search for geometrical similarity in a series of nonpeptide angiotensin II receptor antagonists.

A 3D QSAR methodology based on the combined use of conformational analysis and chemometrics was applied to perform a comparative analysis of the 3D conformational features of 13 nonpeptide angiotensin II receptor antagonists showing different levels of binding affinity. Conformational analysis by using a molecular mechanics MM2 method was carried out for each of these structures to obtain conformational minima. These minima were described by ten interatomic distances which define the relative spatial disposition of five significant atoms belonging to relevant functional groups present in all the 13 molecules. The structure-activity relationship between the interatomic distances and the biological activity was then assessed by using chemometric methods (cluster analysis, principal component analysis, classification methods). With our indirect approach based on the search for geometrical similarity it was possible, even though structural information on the receptor active site was lacking, to identify the 3D geometrical requirements for the binding affinity of nonpeptide angiotensin II receptor inhibitors.

Amino Acid Sequence↗

PubMed1977

[Assessment of the premorbid personality in endogenous psychoses. A factor-analytical study of the adjective check list of von Zerssen (author's transl)].

In order to get information about the premorbid personality of patients with endogenous psychosis, we examined the adjective check list of von Zerssen with regard to form and content on a sample of 126 schizophrenic and 31 affective-psychotic patients. The data gathering occured through retrospective evaluation by a close relative of each patient. One aim of the study was the development of a psychometric instrument in order to construct clinically relevant scales, which would allow us to objectify characterizations of the premorbid personality of patients with psychic illness. Another aim was to test the validity of this instrument by investigating the coherence between the obtained test results and the corresponding clinical psychiatric judgments of experts in the form of diagnoses. Finally, we sought to determine if typical premorbid characteristic features give a predisposition for specific aspects of psychotic diseases, in order to be able to differentiate between diverse psychiatric groups of diagnoses. By means of factor analysis (principal component analysis) with Varimax rotation we came to five easily distinguishable clinical-psychological well interpretable factors, from which we derived five scales. These scales seem to be appropriate for the characterization of premorbid personality traits. They represent the following clinical concepts: (1) cyclothymia, (2) sthenia, (3) anancasm, (4) hostility, (5) schizothymia. Formal examination of the factor-analytical proved scales according to criteria of classic test-theory (item-test correlation, reliability, distribution, intercorrelation) showed that we were able to measure rather independent dimensions of premorbid personality by our five scales with sufficient accuracy. To get evidence for the empirical validity of our scales we compared our test results (1) with three groups of different diagnoses concerning premorbid personality and (2) with the two diagnostic groups of schizophrenia and affective psychoses. We also tried to work out differential aspects within the diagnostic group of schizophrenia for four subgroups. As criteria for validity we sued clinical judgments of psychiatrists both for the premorbid personality and for the diagnosis of the present disease. On the whole our adjective check list turned out be as useful instrument to get a discriminating description of premorbid characteristic features which is better than a global evaluation in form of a single diagnosis. First First indications of the practical importance of our scales are discussed.

Affective Symptoms↗