Search results for "multivariate statistics"
showing 10 items of 290 documents
Multivariate analysis of the modifications induced by an environmental acoustic cue on rat exploratory behavior.
2007
The aim of the present paper is to study by means of a multivariate analysis the modifications induced by an environmental acoustic cue on the structure of rat exploratory behavior. Adult male Wistar rats were observed during the exploration of a soundproof observation box. Each rat was acoustically stimulated after 150 s from the beginning of the experimental session, lasting 300 s, and recorded through a digital videocamera. A frame by frame analysis was thereafter carried out using a professional video-recording system. Thirteen behavioral patterns were selected: immobility, immobile-sniffing, walking, rearing, climbing, chewing, paw-licking, face-grooming, body-grooming, head-turning, t…
Extended Granger causality: a new tool to identify the structure of physiological networks.
2015
Granger causality (GC) is a very popular tool for assessing the presence of directional interactions between two time series of a multivariate data set. In its original formulation, GC does not account for zero-lag correlations possibly existing between the observed time series. In the present study we compare the GC with a novel measure, termed extended GC (eGC), able to capture instantaneous causal relationships. We present a two-step procedure for the practical estimation of eGC based on first detecting the existence of zero-lag correlations, and then assigning them to one of the two possible causal directions using pairwise measures of non-Gaussianity. The proposed method was validated …
Treating missing data in a clinical neuropsychological dataset--data imputation.
2001
Missing data frequently reduce the applicability of clinically collected data in research requiring multivariate statistics. In data imputation, missing values are replaced by predicted values obtained from models based on auxiliary information. Our aim was to complete a clinical child neuropsychological data set containing 5.2% of missing observations. This was to be used in research requiring multivariate statistics. We compared four data imputation methods by artificially deleting some data. A real-donor imputation method which preserved the parameter estimates and which predicted the observed values with acceptable accuracy was used to complete the data set. In addressing the lack of st…
Pimonidazole labelling and response to fractionated irradiation of five human squamous cell carcinoma (hSCC) lines in nude mice: The need for a multi…
2006
To investigate the influence on local control after fractionated radiotherapy of hypoxia measured in unirradiated tumours using the hypoxic marker Pimonidazole, using multivariate approaches.Five human squamous cell carcinoma lines (FaDu, UT-SCC-15, UT-SCC-14, XF354, and UT-SCC-5) were transplanted subcutaneously into the right hind-leg of NMRI nude mice. Histological material was collected from 60 unirradiated tumours after injection of Pimonidazole. The relative hypoxic area within the viable tumour area (Pimonidazole hypoxic fraction, pHF) was determined in seven serial 10 microm cross-sections per tumour by fluorescence microscopy and computerized image analysis. Local tumour control wa…
Effects of ambient temperature, humidity, and other meteorological variables on hospital admissions for angina pectoris.
2012
Background: Seasonal peaks in cardiovascular disease incidence have been widely reported, suggesting weather has a role. Design The aim of our study was to determine the influence of climatic variables on angina pectoris hospital admissions. Methods: We correlated the daily number of angina cases admitted to a western Sicilian hospital over a period of 12 years and local weather conditions (temperature, humidity, wind force and direction, precipitation, sunny hours and atmospheric pressure) on a day-to-day basis. A total of 2459 consecutive patients were admitted over the period 1987–1998 (1562 men, 867 women; M/F – 1:8). Results: A seasonal variation was found with a noticeable winter pea…
Comparison of different statistical approaches to evaluate morphometric sperm subpopulations in men.
2016
This study was designed to characterize morphometric sperm subpopulations in normozoospermic men by using different statistical methods and examining their suitability to classify correctly different sperm nuclear morphologies present in human ejaculates. Ejaculates from 21 normozoospermic men were collected for the study. After semen collection and analysis, samples were prepared for morphometric determination. At least 200 spermatozoa per sample were assessed for sperm morphometry by computer-assisted sperm morphometry analysis (CASA-Morph) using fluorescence. Clustering and discriminant procedures were performed to identify sperm subpopulations from the morphometric data obtained. Cluste…
Influence of climatic variables on acute myocardial infarction hospital admissions
2009
BACKGROUND: Seasonal peaks in acute myocardial infarction (AMI) incidence have been widely reported. Weather has been postulated to be one of the elements at the basis of this association. The aim of our study was to determine the influence of seasonal variations and weather on AMI hospital admissions. METHODS: We correlated the daily number of AMI cases admitted to a western Sicily hospital over twelve years and weather conditions on a day-to-day basis. Information on temperature, humidity, wind force and direction, precipitation, sunny hours and atmospheric pressure was obtained from the local Birgi Air Force base. A total of 3918 consecutive patients were admitted with AMI over the perio…
Intravenous bisphosphonate-related osteonecrosis of the jaws: Influence of coadjuvant antineoplastic treatment and study of buccodental condition
2012
Objectives: To determine whether coadjuvant antineoplastic treatment can influence the number and size of bone exposures among patients with intravenous bisphosphonate-related osteonecrosis of the jaws (iBRONJ), and to analyze the buccodental condition of these patients. Material and methods: The study sample comprised 67 patients with iBRONJ, 53 patients without iBRONJ receiving treatment with intravenous bisphosphonates, and 36 healthy subjects. In all three groups, measurements were made of the CAO index and of resting whole saliva and stimulated whole saliva. In the patients with iBRONJ, the size (cm) and number of bone exposures were recorded. The data obtained were subjected to analys…
Gender differences in original Archivos de Bronconeumología publications, 2001-2018
2021
Abstract Introduction Gender inequality exists in scientific publications. The aim of this study was to determine changing patterns in gender differences and factors associated with the positioning of authors’ names in original articles published in Archivos de Bronconeumologia (AB). Methods We performed a bibliometric study of articles published in AB between 2001 and 2018. Author gender was analyzed in four scenarios: first author, last author, middle authors, and mentee authors. Comparisons were made by authors’ specialties, funding received, multicenter studies, specialist areas, and others. Multivariate models adjusted for the percentage of registered physicians in the Spanish health s…
Periodic limb movements during sleep and blood pressure changes in sleep apnoea: Data from the European Sleep Apnoea Database
2020
International audience; Background and objective: OSA and PLMS are known to induce acute BP swings during sleep. Our current study aimed to address the independent effect of PLMS on BP in an unselected OSA patient cohort.Methods: This cross-sectional analysis included 1487 patients (1110 males, no previous hypertension diagnosis or treatment, mean age: 52.5 years, mean BMI: 30.5 kg/m2 ) with significant OSA (defined as AHI ≥ 10) recruited from the European Sleep Apnoea Cohort. Patients underwent overnight PSG. Patients were stratified into two groups: patients with significant PLMS (PLMSI > 25 events/hour of sleep) and patients without significant PLMS (PLMSI < 25 events/hour of sleep). SBP…