Search results for "multivariate"
showing 10 items of 1520 documents
Disentangling directional and fluctuating asymmetry in a genome-wide association study.
2018
8 pages; International audience; Although directional and fluctuating asymmetry have been frequently assessed independently, they are indeed associated concepts both in theory and in practice. However, they can be difficult to disentangle in genome-wide association studies, where the appropriate shape statistics are not fully developed. Although the usage of Procrustes distances to overcome this problem may be tempting, this does not reliably help to identify the underlying genetic components of directional and fluctuating asymmetries. Here, similarities and differences among different approaches have revealed that the genetic component of the skull asymmetry in this population of mice is m…
Recurrent lumbar disc herniation: Is there a correlation with the surgical technique? A multivariate analysis
2019
Purpose: The recurrence of a lumbar disc herniation (LDH) is a common cause of poor outcome following lumbar discectomy. The aim of this study was to assess a potential relationship between the incidence of recurrent LDH and the surgical technique used. Furthermore, we tried to define the best surgical technique for the treatment of recurrent LDH to limit subsequent recurrences. Materials and Methods: A retrospective study was conducted on 979 consecutive patients treated for LDH. A multivariate analysis tried to identify a possible correlation between (1) the surgical technique used to treat the primary LDH and its recurrence; (2) technique used to treat the recurrence of LDH and the secon…
TP53 mutations and S-phase fraction but not DNA-ploidy are independent prognostic indicators in laryngeal squamous cell carcinoma
2005
To prospectively evaluate the prognostic significance of TP53, H-, K-, and N-Ras mutations, DNA-ploidy and S-phase fraction (SPF) in patients affected by locally advanced laryngeal squamous cell carcinoma (LSCC). Eight-one patients (median follow-up was 71 months) who underwent resective surgery for primary operable locally advanced LSCC were analyzed. Tumor DNA was screened for mutational analysis by PCR/SSCP and sequencing. DNA-ploidy and SPF were performed by flow cytometric analyses. Thirty-six patients (44%) had, at least, a mutation in the TP53 gene. Of them, 22% (8/36) had double mutations and 3% (1/36) had triple mutations. In total, 46 TP53 mutations were observed. The majority (41…
Representation of Stationary Multivariate Gaussian Processes Fractional Differential Approach
2011
In this paper, the fractional spectral moments method (H-FSM) is used to generate stationary Gaussian multivariate processes with assigned power spectral density matrix. To this aim, firstly the N-variate process is expressed as sum of N fully coherent normal random vectors, and then, the representation in terms of HFSM is used.
Modelling Systemic Cojumps with Hawkes Factor Models
2013
Instabilities in the price dynamics of a large number of financial assets are a clear sign of systemic events. By investigating a set of 20 high cap stocks traded at the Italian Stock Exchange, we find that there is a large number of high frequency cojumps. We show that the dynamics of these jumps is described neither by a multivariate Poisson nor by a multivariate Hawkes model. We introduce a Hawkes one factor model which is able to capture simultaneously the time clustering of jumps and the high synchronization of jumps across assets.
A class of multivariate type I generalized logistic distributions
2010
The logistic distribution has found important applications in many different fields and several different forms of generalizations have been proposed in the literature. However it seems, with a few exceptions, that there are not in the literature forms of multivariate generalized logistic distributions. In this paper we focus on the type I generalized logistic distribution and, based on a procedure of multivariate transformation of multivariate exponential distributions, we introduce a class of multivariate type I generalized logistic distributions. We provide some examples of bivariate and multivariate distributions of this class.
Virtudes escolares percibidas por estudiantes y docentes ecuatorianos: diferencias según sexo, establecimiento y roles
2020
El objetivo del estudio es evaluar la virtuosidad percibida en organizaciones escolares y las diferencias por tipo de centro educativo (fiscal, municipal); sexo (mujer, hombre) y rol (estudiantes, docentes). Se trató de un estudio instrumental basado en el análisis de la estructura factorial y la fiabilidad de un cuestionario para evaluar virtudes percibidas en escuelas (VPOE); y, de un estudio descriptivo transversal que analizó diferencias por sexo, rol y tipo de organizaciones escolares con relación a las virtudes percibidas. Se trabajó con una muestra de 550 estudiantes (49.28 % mujeres) y 105 docentes (47.62% mujeres). El análisis factorial determinó un modelo de cuatro factores que pe…
Univariate and multivariate properties of wind velocity time series
2009
We analyze the time series of hourly average wind speeds measured at 29 different stations located in Sicily, a region with a complex morphology. The investigation, performed from the univariate as well as the multivariate point of view, evidences that the statistical properties of wind at the single sites have features that are not reproduced by standard models and, thus, require specific modeling. Moreover, the synchronous evolution of wind velocity presents a cluster structure, obtained with different algorithms, that persists in the standard deviation too.
Assessment of Knowledge, Attitudes, and Propensity towards HPV Vaccine of Young Adult Students in Italy
2020
Background: Human Papillomavirus (HPV) is a common sexually transmitted infection (STI), representing the main cause of genital warts and cervical cancer. This cross-sectional study evaluated knowledge and attitudes about HPV infection, related diseases, and prevention and propensity towards HPV vaccine among undergraduate students. Methods: An online and written survey about HPV and its prevention, targeted to young adults of both genders, was addressed to students attending health sciences and other schools at Universities of Genoa and Bari. Results: The overall median knowledge and attitude scores were 56.3% (25&ndash
Obesity and survival in operable breast cancer patients treated with adjuvant anthracyclines and taxanes according to pathological subtypes: a pooled…
2013
Obesity is an unfavorable prognostic factor in breast cancer (BC) patients regardless of menopausal status and treatment received. However, the association between obesity and survival outcome by pathological subtype requires further clarification. METHODS: We performed a retrospective analysis including 5,683 operable BC patients enrolled in four randomized clinical trials (GEICAM/9906, GEICAM/9805, GEICAM/2003-02, and BCIRG 001) evaluating anthracyclines and taxanes as adjuvant treatments. Our primary aim was to assess the prognostic effect of body mass index (BMI) on disease recurrence, breast cancer mortality (BCM), and overall mortality (OM). A secondary aim was to detect differences o…