Search results for "Correlation"
showing 10 items of 2282 documents
COMMUNICATION. OBSERVATIONS ON THE 121-Sb MÖSSBAUER PARAMETERS OF ANTIMONY (III) COMPOUNDS FEATURING A PYRAMIDAL SbS3SKELETAL UNIT
1991
Abstract A linear correlation between the chemical isomer shift and the quadrupole coupling constant for a number of antimony tris-thiolates has been evidenced. This behaviour can be rationalized on considering a modulation of the s/p character of the lone pair of electrons from the influence of secondary bonds.
Sparse model-based network inference using Gaussian graphical models
2010
We consider the problem of estimating a sparse dynamic Gaussian graphical model with L1 penalized maximum likelihood of structured precision matrix. The structure can consist of specific time dynamics, known presence or absence of links in the graphical model or equality constraints on the parameters. The model is defined on the basis of partial correlations, which results in a specific class precision matrices. A priori L1 penalized maximum likelihood estimation in this class is extremely difficult, because of the above mentioned constraints, the computational complexity of the L1 constraint on the side of the usual positive-definite constraint. The implementation is non-trivial, but we sh…
Sign and Rank Covariance Matrices: Statistical Properties and Application to Principal Components Analysis
2002
In this paper, the estimation of covariance matrices based on multivariate sign and rank vectors is discussed. Equivariance and robustness properties of the sign and rank covariance matrices are described. We show their use for the principal components analysis (PCA) problem. Limiting efficiencies of the estimation procedures for PCA are compared.
Dynamic light scattering by preserved skimmed cow milk: A comparison of two-colour and three-dimensional cross-correlation experiments
2008
We investigate the dynamic light scattering of preserved skimmed cow milk and compare the performance of a standard two-colour (2C) cross-correlation setup with the recently developed three-dimensional (3D) cross-correlation setup. Undiluted milk could only be investigated using the 3D setup because of too low signal-to-noise ratio of the 2C setup. A tenfold diluted milk, however, could be investigated by both setups, and comparable results for the dynamics of the sample were obtained thus demonstrating the equivalence of the decorrelation schemes. On the other hand, we found that the dynamics of the milk is strongly altered upon dilution. This finding elucidates the benefits of the new 3D …
Cross-Cultural Adaptation and Reliability of the Back Pain and Body Posture Evaluation Instrument (BackPEI) to the Spanish Adolescent Population
2021
The prevalence of back pain (BP) among children and adolescents has increased over recent years. Some authors advocate promoting back-health education in the school setting. It is therefore important to adopt a uniform suite of assessment instruments to measure the various constructs. The present study aimed to perform a cultural adaptation of a validated measurement instrument (BackPEI), beginning with a translation and cultural adaptation phase, followed by a second phase to test reliability using a test-retest design. The translation and cross-cultural adaptation were performed based on the guidelines. Reliability was tested by applying the questionnaire to 224 secondary school students,…
Cross-Cultural Adaptation, Translation, and Validation of the Spanish Foot and Ankle Outcome Score Questionnaire
2020
The Spanish Foot and Ankle Outcome Score questionnaire (FAOS‐S) may be considered a health evaluation tool with 42 questions for assessing foot health disorders. To date, FAOS has been validated in different languages, but a Spanish version was lacking. Consequently, the purpose of this study was to translate and validate the Spanish version of the FAOS (FAOS es). A suitable method was developed for the translation protocol and cross‐cultural validation from Swedish to Spanish. Regarding the total marks from each domain, agreement degrees and confidence were analysed using the Cronbach's α and intraclass correlation coefficient, respectively. In addition, the mean ± SD differences between p…
Trauma in cirrhosis: an indicator of the pattern of alcohol abuse in different societies.
1991
While some morbidities associated with the excessive use of alcohol are related to the total amount of alcohol consumed--cirrhosis being an example--other pathologies, such as trauma and those of psycho-social origin, are mainly related to the frequency of acute alcoholic intoxication rather than to the total amount consumed. The balance between these two types of alcohol-associated morbidities can provide an indication of the relative frequency of intoxication, and thus of the pattern of alcohol abuse in a population. Since trauma is highly associated with acute alcoholic intoxication, the prevalence of bone fractures was determined in cirrhotics in nine countries. The prevalence of rib an…
Repeatability and reliability of the diabetic foot self-care questionnaire in Arabic patients: A transcultural adaptation.
2022
Abstract Purpose The diabetic foot self-care questionnaire is considered a self-care evaluation tool with 16 questions for assessing diabetic foot health disorders. To date, the DFSQ has been validated in different languages, but an Arabic version was lacking. Consequently, the purpose of this study was to translate and validate the Arabic version of the DFSQ (DFSQ-AR). Method A suitable method was developed for the translation protocol and cross-cultural validation from Spanish to Arabic. Regarding the total marks from each sub-scale, agreement degrees and confidence were analyzed using Cronbach's α and intraclass correlation coefficient (ICC), respectively. In addition, the mean ± standar…
Automatic Extraction of Blood Vessels, Bifurcations and End Points in the Retinal Vascular Tree
2008
In this paper we present an effective algorithm for automated extraction of the vascular tree in retinal images, including bifurcations, crossovers and end-points detection. Correct identification of these features in the ocular fundus helps the diagnosis of important systematic diseases, such as diabetes and hypertension. The pre-processing consists in artefacts removal based on anisotropic diffusion filter. Then a matched filter is applied to enhance blood vessels. The filter uses a full adaptive kernel because each vessel has a proper orientation and thickness. The kernel of the filter needs to be rotated for all possible directions. As a consequence, a suitable kernel has been designed …
Spatial Localization in Manufacturing: A Cross-Country Analysis
2009
This paper employs a homogenous firms' database to investigate industry localiza- tion in European countries. More specifically, we compare, across industries and countries, the predictions of two of the most popular localization indices, i.e., the Ellison and Glaeser index (Ellison and Glaeser, 1997) and the Duranton and Over- man index (Duranton and Overman, 2005). We find that, independently from the index used, localization is a pervasive phenomenon in all countries studied, but the degree of localization is very uneven across industries in each country. Furthermore, we find that the two indices significantly diverge in predicting the intensity of the forces generating localization with…