Statistical classification based on observations of random Gaussian fields

The problem of classification of objects located in domain D ⊂ R2 based on observations of random Gaussian fields with a factorized covariance function is considered. The first‐order asymptotic expansion for the expected error regret is presented. Obtained numerical results allow us to compare suggested expansion for some widely applicable models of spatial covariance function. Statistinis klasifikavimas remiantis atsitiktinių Gauso laikų stebėjimais Santrauka Nagrinejamas uždavinys apie objektu iš srites D C R 2 klasifikavima, remiantis atsitiktiniu Gauso lauku stebejimais. Pateikti asimptotiniai laukiamos paklaidos iverčiai. Atlikus skaitinio modeliavimo eksperimenta naujasis skleidinys lyginamas su kitais žinomais skleidimais. First Published Online: 14 Oct 201

Exotoxin-encoding gene content in community-acquired and hospital-acquired methicillin-resistant Staphylococcus aureus

AbstractReports of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) causing hospital infections are increasing, and it is questionable whether the existing molecular definition of CA-MRSA is suitable for the characterization of all strains involved. The 821 methicillin-resistant S. aureus (MRSA) isolates recovered from patients in Health Region East, Norway during the period 1991—2006 were characterized by multilocus sequence typing (MLST), staphylococcal cassette chromosome mec (SCCmec) typing, staphylococcal protein A (spa) gene typing, and their content of exotoxin-encoding genes. Cluster analysis based on exotoxin-encoding gene content was performed to separate the MRSA isolates into valid clusters with respect to microbiological characteristics. The analysis gave a four-cluster structure, and the four toxin clusters differed in the genetic lineages they included and in the diversity of the genetic lineages. A few genetic lineages were present in several toxin clusters. These results support the theory that mobile genetic elements encoding virulence genes do not move randomly among genetic lineages, but are restricted by the clonal lineages’ genetic background. Using the molecular criteria, MLST type, SCCmec type and the presence of the lucS/F-Panton–Valentine leukocidin (PVL) gene to define a CA-MRSA isolate, it was found that the CA-MRSA isolates mainly grouped together in two toxin clusters with a low prevalence of exotoxin-encoding genes. Statistical analyses supported the conclusion that toxin clusters with CA-MRSA genetic lineages were characterized by a low prevalence of exotoxin-encoding genes, whereas toxin clusters with hospital-acquired MRSA genetic lineages were characterized by a higher prevalence of exotoxin-encoding genes

Comparison of two estimators of mean function in LDA of spatially correlated Gaussian data

The problem of linear discriminant analysis of an observation of Gaussian random field into one of two populations is considered. In this paper we analyze the performance of the plug‐in linear discriminant function, when unknown means are estimated from the training samples. The generalized least squares and the ordinary least squares estimators are used. Obtained asymptotic expansions for the expected error rate are compared numerically in the case of spherical models for population covariances. Dviejų vidurkio įvertinių palyginimas tiesinėje erdvėje koreliuotų Gauso stebėjimų diskriminantinėje analizėje Santrauka Straipsnyje sprendžiamas atsitiktinio Gauso lauko stebejimu tiesines diskriminantines analizes uždavinys dvieju klasiu atveju. Gauti pirmos eile asimptotiniai tiketinos klasifikavimo klaidos skleidiniai atvejui, kai i Bajeso klasifikavimo taisykle istatome maksimalaus tiketinumo bei empirini vidurkiu iverčius. Atliktas skaitinis asimptotiniu klasifikavimo klaidu palyginimas tam tikrai kaimynystes schemai bei sferinei koreliaciju funkcijai.  First Published Online: 14 Oct 201

Change in psychotropic drug use in Norwegian nursing homes between 2004 and 2011

BACKGROUND: We aimed to assess whether there were any changes in the use of psychotropic drugs in Norwegian nursing homes between 2004 and 2011. Also, we investigated whether the predictors of use of specific psychotropic drug groups have changed. METHODS: We conducted a secondary analysis of two cohort studies of two Norwegian nursing home samples (2004/05 and 2010/11). Multivariate models were applied. RESULTS: We found a significant decrease in the prescription of antipsychotic drugs between 2004 and 2011 (0.63 OR, 95%CI = 0.49-0.82, p < 0.001) even after adjusting for relevant demographic and clinical variables. There are only minor changes for the other psychotropic drugs. We found that (1) the use of specific psychotropic drug groups as well as the number of psychotropic drugs used was associated with more affective symptoms and (2) the use of specific psychotropic drug groups as well as the number of psychotropic drugs used was associated with lower scores on the Physical Self-Maintenance scale. CONCLUSION: This is the first study to show a robust decrease in antipsychotic drug use in nursing home patients with dementia unrelated to possible changes in case mix. The change might be explained by treatment recommendations against its use except in the most severe conditions of aggression or psychosis. Our findings indicate that it takes several years to implement scientific knowledge in clinical practice in nursing homes