Search results for "statistical [methods]"
showing 10 items of 1664 documents
Assessing the MALDI-TOF MS sample preparation procedure to analyze the influence of thermo-oxidative ageing and thermo-mechanical degradation on poly…
2011
[EN] Multiple processing by means of successive injection cycles was used to simulate the thermo-mechanical degradation effects on the oligomeric distribution of PLA under mechanical recycling. Likewise, an accelerated thermal ageing over PLA glass transition was performed in order to simulate its service life. MALDI-TOF MS was used for the analysis and the sample preparation procedure was assessed by means of a statistical Design of Experiments (DoE). The quality effects in use for the analysis were signal-to-noise ratio and Resolution. Different matrixes, analyte/matrix proportions and the use of NaTFA as cationization agent were considered. A deep inspection of the statistical results pr…
Southern-Tyrrhenian seismicity in space-time-magnitude domain
2006
An analysis is conducted on a catalogue containing more than 2000 seismic events occurred in the southern Tyrrhenian Sea between 1988 and October 2002, as an attempt to characterise the main seismogenetic processes active in the area in space, time and magnitude domain by means of the parameters of phenomenological laws. We chose to adopt simple phenomenological models, since the low number of data did not allow to use more complex laws. The two main seismogenetic volumes present in the area were considered for the purpose of this work. The first includes a nearly homogeneous distribution of hypocentres in a NW steeply dipping layer as far as a…
Topology of correlation-based minimal spanning trees in real and model markets
2003
We present here a topological characterization of the minimal spanning tree that can be obtained by considering the price return correlations of stocks traded in a financial market. We compare the minimal spanning tree obtained from a large group of stocks traded at the New York Stock Exchange during a 12-year trading period with the one obtained from surrogated data simulated by using simple market models. We find that the empirical tree has features of a complex network that cannot be reproduced, even as a first approximation, by a random market model and by the one-factor model.
Suppression of the speckle noise in solid polymer samples: a light scattering study
1994
The speckle effect disturbs the measurement of spatial correlation functions in solid polymer samples by light scattering. To be able to extract the desired correlations from the measurements, the speckle noise must be suppressed. This is possible by moving the sample during the measurement. In this paper we demonstrate that a sufficient reduction of speckle contrast can be achieved even in samples of restricted dimensions or with a preferential direction.
Performance potential for simulating spin models on GPU
2012
Graphics processing units (GPUs) are recently being used to an increasing degree for general computational purposes. This development is motivated by their theoretical peak performance, which significantly exceeds that of broadly available CPUs. For practical purposes, however, it is far from clear how much of this theoretical performance can be realized in actual scientific applications. As is discussed here for the case of studying classical spin models of statistical mechanics by Monte Carlo simulations, only an explicit tailoring of the involved algorithms to the specific architecture under consideration allows to harvest the computational power of GPU systems. A number of examples, ran…
Prenatal exposure to organochlorine compounds and lung function during childhood
2019
Introduction: Prenatal exposure to organochlorine compounds (OCs) can increase the risk of reported respiratory symptoms in children. It remains unclear whether these compounds can also impact on lung function. We assessed the association between prenatal exposure to OCs and lung function during childhood. Methods: We included 1308 mother-child pairs enrolled in a prospective cohort study. Prenatal concentrations of p,p′-dichlorodiphenyltrichloroethane [p,p′-DDT], p,p′-dichlorodiphenyldichloroethylene [p,p′-DDE], hexachlorobenzene [HCB], and seven polychlorinated biphenyls [PCBs] were measured in cord blood. Spirometry was performed in the offspring at ages 4 (n = 636) and 7 years (n = 1192…
Measuring lung function in asthmatic children: A spirometry and forced oscillation technique (FOT) comparison
2016
Background: Spirometry is the most common pulmonary function test used in asthma diagnosing. However, it requires good patient co-operation. FOT has gained increasing attention for the measurement of pulmonary function in children because it is performed at steady state breathing. Aim: To compare spirometry and FOT in order to discriminate severity of asthma according to GINA. Methods: Spirometry and FOT were performed in 176 out-patient asthmatic children (5-16 year), 100 (57%) with naive Persistent Asthma (PA) and 76 (43%) with Intermittent Asthma (IA), consecutively enrolled at the IBIM pediatric clinic. Two principal component analyses (PCA) were performed, the first (PCA1) based on FEV…
Tabula 0.3 beta
2010
The final aim of the majority of statistical analyses is to create a set of statistical tables for publication. Generally complex statistical survey reports contain a lot of tables which usually have more than two entries. In order to create tables like these, you have first to run a lot of Stata commands and to write them by hand. This process is error prone and it’s difficult to create tables with more than four entries using ordinary Stata commands. Tabula is not a Stata command but a complete software written in C++, with a user-friendly GUI. The main aims of Tabula are to automate the production of reports and to minimize human errors. It allows you to create your statistical table thr…
Non-Equilibrium Markov State Modeling of the Globule-Stretch Transition
2016
We describe a systematic approach to construct coarse-grained Markov state models from molecular dynamics data of systems driven into a nonequilibrium steady state. We apply this method to study the globule-stretch transition of a single tethered model polymer in shear flow. The folding and unfolding rates of the coarse-grained model agree with the original detailed model. We demonstrate that the folding and unfolding proceeds through the same narrow region of configuration space but along different cycles.
Statistical correlation of fractional oscillator response by complex spectral moments and state variable expansion
2016
Abstract The statistical characterization of the oscillator response with non-integer order damping under Gaussian noise represents an important challenge in the modern stochastic mechanics. In fact, this kind of problem appears in several issues of different type (wave propagation in viscoelastic media, Brownian motion, fluid dynamics, RLC circuit, etc.). The aim of this paper is to provide a stochastic characterization of the stationary response of linear fractional oscillator forced by normal white noise. In particular, this paper shows a new method to obtain the correlation function by exact complex spectral moments. These complex quantities contain all the information to describe the r…