57 result(s)
Page Size: 10, 20, 50
Export: bibtex, xml, json, csv
Order by:

CNR Author operator: and / or
more
Typology operator: and / or
Language operator: and / or
Date operator: and / or
more
Rights operator: and / or
2009 Article Unknown

A heavy-tailed empirical Bayes method for replicated microarray data
Salas-gonzalez D., Kuruoglu E. E., Ruiz D. P.
DNAmicroarray has been recognized as being an important tool for studying the expression of thousands of genes simultaneously. These experiments allow us to compare two different samples of cDNA obtained under different conditions. A novel method for the analysis of replicated microarray experiments based upon the modelling of gene expression distribution as a mixture of alpha-stable distributions is presented. Some features of the distribution of gene expression, such as Pareto tails and the fact that the variance of any given array increases concomitantly with an increase in the number of genes studied, suggest the possibility of modelling gene expression distribution on the basis of alpha-stable density. The proposed methodology uses very well known properties of alpha-stable distribution, such as the scale mixture of normals. A Bayesian log-posterior odds is calculated, which allows us to decide whether a gene is expressed differentially or not. The proposed methodology is illustrated using simulated and experimental data and the results are compared with other existing statistical approaches. The proposed heavy-tail model improves the performance of other distributions and is easily applicable to microarray gene data, specially if the dataset contains outliers or presents high variance between replicates.Source: Computational statistics & data analysis (Print) 53 (2009): 1535–1546. doi:10.1016/j.csda.2008.08.008
DOI: 10.1016/j.csda.2008.08.008

See at: DOI Resolver | CNR People | www.sciencedirect.com


2009 Article Unknown

Astrophysical image separation by blind time-frequency source separation methods
Ozgen M. T., Kuruoglu E. E., Herranz D.
In this paper, two prevalent blind time-frequency (TF) source separation methods in the literature are adapted to astrophysical image mixtures and four algorithms are developed to separate them into their astrophysical components. The components considered in this work are cosmic microwave background (CMB) radiation, galactic dust and synchrotron, among which the CMB component is emphasized. These simulated components mixed via realistic coefficients are subjected to simulated additive, nonstationary Gaussian noise components of realistic power levels, to yield image mixtures on which our orthogonal and nonorthogonal TF algorithms are applied. The developed algorithms are compared with the FastICA algorithm and CMB component is found to be recovered with an improvement reaching to 3.25 decibels from CMB-synchrotron mixtures. The proposed techniques are believed to be generically applicable in separating other types of astrophysical components as well.Source: Digital signal processing (Print) 19 (2009): 360–369. doi:10.1016/j.dsp.2007.12.003
DOI: 10.1016/j.dsp.2007.12.003

See at: DOI Resolver | CNR People | www.sciencedirect.com


2009 Article Unknown

Finite mixture of alpha-stable distributions
Salas-gonzalez D., Kuruoglu E. E., Ruiz D. P.
Over the last decades, the ±-stable distribution has proved to be a very efficient model for impulsive data. In this paper, we propose an extension of stable distributions, namely mixture of ±-stable distributions to model multimodal, skewed and impulsive data. A fully Bayesian framework is presented for the estimation of the stable density parameters and the mixture parameters. As opposed to most previous work on mixture models, the model order is assumed unknown and is estimated using reversible jump Markov chain Monte Carlo. It is important to note that the Gaussian mixture model is a special case of the presented model which provides additional flexibility to model skewed and impulsive phenomena. The algorithm is tested using synthetic and real data, accurately estimating ±-stable parameters, mixture coefficients and the number of components in the mixture.Source: Digital signal processing (Print) 19 (2009): 250–264. doi:10.1016/j.dsp.2007.11.004
DOI: 10.1016/j.dsp.2007.11.004

See at: DOI Resolver | CNR People | www.sciencedirect.com


2009 Conference object Unknown

ICA by maximizing non-stability
Wang B., Kuruoglu E. E., Zhang J.
We propose a new approach for ICA by maximizing the non-stability contrast function in this paper. This new version of ICA is motivated by the Generalized Central Limit Theorem (GCLT), an important extension of classical CLT. We demonstrate that the classical ICA based on maximization of non-Gaussianity is a special case of the new approach of ICA we introduce here which is based on maximization of non-Stability with certain constraints. To be able to quantify non-stability, we introduce a new measure of stability namely Alpha-stable negentropy. A numerical gradient ascent algorithm for the maximization of the alpha-stable negentropy with the objective of source separation is also introduced in this paper. Experiments show that ICA by maximum of non-stability performs very successfully in impulsive source separation problems.Source: Independent Component Analysis and Signal Separation. 8th International Conference, pp. 179–186, Paraty, Rio Janerio, Brasile, 15-18 Marzo 2009
DOI: 10.1007/978-3-642-00599-2_23

See at: DOI Resolver | link.springer.com | CNR People


2009 Article Unknown

Modelling and assessing differential gene expression using the alpha stable distribution
Salas-gonzalez D., Kuruoglu E. E., Ruiz D. P.
After normalization, the distribution of gene expressions for very different organisms have a similar shape, usually exhibit heavier tails than a Gaussian distribution, and have a certain degree of asymmetry. Therefore, this distribution has been modeled in the literature using different parametric families of distributions, such the Asymmetric Laplace or the Cauchy distribution. Moreover, it is known that the tails of spot-intensity distributions are described by a power law and the variance of a given array increases with the number of genes. These features of the distribution of gene expression strongly suggest that the alpha-stable distribution is suitable to model it. In this work, we model the error distribution for gene expression data using the alpha-stable distribution. This distribution is tested successfully for four different datasets. The Kullback-Leibler, Chi-square and Hellinger tests are performed to compare how alpha-stable, Asymmetric Laplace and Gaussian fit the spot intensity distribution. The alpha-stable is proved to perform much better for every array in every dataset considered. Furthermore, using an alpha-stable mixture model, a Bayesian log-posterior odds is calculated allowing us to decide whether a gene is differently expressed or not. This statistic is based on the Scale Mixture of Normals and other well known properties of the alpha-stable distribution. The proposed methodology is illustrated using simulated data and the results are compared with the other existing statistical approach.Source: The international journal of biostatistics 5 (2009): 16–24. doi:10.2202/1557-4679.1120
DOI: 10.2202/1557-4679.1120

See at: DOI Resolver | www.bepress.com | CNR People


2009 Article Unknown

Permittivity range profile reconstruction of multilayered structures from microwave backscattering data by using particle swarm optimization
Genovesi S., Salerno E., Monorchio A., Manara G.
A method for the investigation of multilayered structures by using microwave probes is proposed. An iterative optimization procedure reconstructs the permittivity range profiles of such structures from backscattering data by optimizing a functional with a data term and a regularization term, including a line process to overcome the global smoothness enforced by classical regularization.Source: Microwave and optical technology letters (Print) 51 (2009): 2390–2394. doi:10.1002/mop.24642
DOI: 10.1002/mop.24642

See at: DOI Resolver | onlinelibrary.wiley.com | CNR People


2009 Article Unknown

Heart deformation pattern analysis through shape modelling
Moroni D., Colantonio S., Salvetti O., Salvetti M.
In this paper, we present an approach to the description of time-varying anatomical structures. The main goal is to compactly but faithfully describe the whole heart cycle in such a way to allow for deformation pattern characterization and assessment. Using such an encoding, a reference database can be built, thus permitting similarity searches or data mining procedures.Source: Pattern recognition and image analysis 19 (2009): 262–270. doi:10.1134/S1054661809020084
DOI: 10.1134/S1054661809020084

See at: DOI Resolver | link.springer.com | CNR People


2009 Article Unknown

Il Web semantico
Martinelli M.
Interview on Semantic WebSource: Internet magazine (Lond.) 135 F (2009): 82–83.

See at: CNR People


2009 Conference object Unknown

A decision support system for aiding heart failure management
Colantonio S., Martinelli M., Moroni D., Salvetti O., Chiarugi F., Emmanouilidou D.
The purpose of this paper is to present an effective way to achieve a high-level integration of a Clinical Decision Support System in the general process of Heart Failure care and to discuss the advantages of such an approach. In particular, the relevant and significant medical knowledge and experts' know-how have been modelled according to an ontological formalism extended with a base of rules for inferential reasoning. These have been also combined with advanced analytical tools for data processing. In particular, methods for the segmentation of echocardiographic image sequences and algorithms for ECG processing have been implemented and integrated into the system.Source: Ninth International Conference on Intelligent Systems Design and Applications, pp. 351–356, Pisa, 30 NOvember -2 December 2009
DOI: 10.1109/ISDA.2009.117

See at: DOI Resolver | ieeexplore.ieee.org | CNR People


2009 Conference object Unknown

Brass instrument making in Milan: 1800 - 1850
Carreras F., Meroni C.
Source: Romantic Brass Symposium, Berna, 2009

See at: CNR People


2009 Conference object Unknown

Agostino Rampone e il brevetto del 1879 sugli strumenti a fiato metallici a doppia parete
Carreras F.
Wind instruments built using two coaxial pipes have introduced in Europe at the beginning of hte XIXth century. In Italy the patent by Agostino Rampone iin 1879 is the first example of the original application of these ideas to metal wind musical instruments. Other makers followed his example in the last decades of the century and in the eraly XXth century.Source: Sedicesimo Convegno Annuale SIdM, Roma, 30 ottobre 2009

See at: CNR People


2009 Conference object Unknown

Event recognition with time varying Hidden Markov Model
Wang Z., Kuruoglu E. E., Yang X., Xu Y., Yu S.
Standard Hidden Markov Model (HMM) and the more general Dynamic Bayesian Network (DBN) models assume stationarity of state transition distribution. However, this assumption does not hold for many real life events of interest. In this paper, we propose a new time sequence model that extends HMM to time varying scenario. The time varying property is realized in our model by explicitly allowing the change of state transition density as the time spent in a particular state passes by. Rather than keeping transition densities at different time spots independent of each other, we exploit their temporal correlation by applying a hierarchical Dirichlet prior. This leads to a more robust time varying model, especially when training data are scarce. We also employ Markov Chain Monte Carlo (MCMC) sampling in learning the MAP estimate of time varying parameters, with a transition kernel incorporating linear optimization. The proposed model is applied to recognizing real video events, and is shown to outperform existing HMM-based methods.Source: IEEE International Conference on Acoustics, Speech and Signal Processing, pp. 1761–1764, Taipei, Taiwan, 19-24 April 2009
DOI: 10.1109/ICASSP.2009.4959945

See at: DOI Resolver | ieeexplore.ieee.org | CNR People


2009 Conference object Unknown

Filtering in the time-frequency domain for the detection of compact objects
Herranz D., Sanz J. L., Kuruoglu E. E.
In this work we propose a detection method for compact sources in the Time-Frequency domain. By exploring the joint Time-Frequency distribution of data and by calculating the time-frequency profile of the compact sources it is possible to improve the detectability of faint point sources. We propose the detection of sources by identification of local maxima (peaks) in the time-frequency Wigner-Ville distribution of the data, previously filtered with a two-dimensional correlator filter. The filter serves the double purpose of enhancing the signal and of reducing cross-terms derived from the Wigner-Ville transform. We test ourmethod and compare it with a the case of the detection in the time domain (filtered with the appropriate one-dimensional correlator), for a situation in which we have faint sources embedded in stationary white Gaussian noise. The detection in the time-frequency domain gives us better significance levels of faint sources (signal-to-noise ratio near 1) than the detection in just the time domain.Source: 17th European Signal Processing Conference, pp. 2067–2071, Glasgow, Scotland, 24-28 August 2009

See at: CNR People


2009 Conference object Unknown

Sparse representatios versus the matched filter
Martinelli F., Sanz J. L.
We have considered the problem of detection and estimation of compact sources immersed in a background plus instrumental noise. Sparse approximation to signals deals with the problem of finding a representation of a signal as a linear combination of a small number of elements from a set of signals called dictionary. The estimation of the signal leads to a minimization problem for the amplitude associated to the sources. We have developed a methodology that minimizes the lp-norm with a constraint on the goodness-of-fit and we have compared different norms against the matched filter.Source: Signal Processing with Adaptive Sparse Structured Representations, Saint-Malo, 06-09 aprile 2009

See at: hal.inria.fr | CNR People


2009 Report Unknown

Error estimation in harmonic CCA
Bedini L., Salerno E.
We complete here what we have reported in [2008-B4-007] with respect to the error estimation for our harmonic CCA solution to the blind identification problem of diffuse component separation in the Planck mission. For our specific case, we evaluate a formula that is also valid when the objective function to be optimized is not a probability density.

See at: CNR People


2009 Report Unknown

La Domomeccatronica negli edifici a passività naturale
Borotto L., Bertini G.
Questa relazione è finalizzata ad analizzare concettualmente e progettualmente degli aspetti riguardanti l'utilità e le reali possibilità di integrazione tra Domomeccatronica e Passive Buildings. L'obiettivo è quello di verificare se nella fase di progettazione di una struttura architettonica a passività naturale vi siano le condizioni intrinseche (impiantistiche) per l'integrazione di un sistema domomeccatronico per il controllo e la gestione di ambienti a risposta intelligente. L'obiettivo è quello di mantenere stabile nel tempo la costante naturale di passività (K-Natural Liabilities) di un edificio passivo. Con questa finalità ci siamo posti inizialmente come obiettivi: Capire intrinsecamente ed estrinsecamente se la metodologia progettuale di una struttura architettonica a passività naturale può realmente definirsi una tecnica costruitiva esaustiva, mediante la presa in esame di una documentazione completa (documentazione fotografica, planimetrie, relazione materiali) attinente ad un progetto, già realizzato, per la costruzione di un edificio a passività naturale. Capire intrinsecamente quali possano essere le potenzialità dell'utilizzo della Domomeccatronica nelle strutture architettoniche a passività naturale (integrazione e gestione di ambienti a risposta intelligente).

See at: CNR People


2009 Report Unknown

Misure non invasive a microonde ed ultrasuoni su materiali lapidei
Algozino L.
During a stage at ISTI's Signals and Images Laboratory, I performed a number of nondestructive near-field microwave tests on lapideous materials relevant to cultural and architectural heritage (different marble samples), to detect and identify possible internal anomalies. The final goal is to experiment resonant microwave sensors developed at ISTI and to validate pre-existing measurements on the same samples, also comparing the results with the typical permittivity values found in the literature. The technique considered uses a narrowband patch antenna whose resonant frequency depends on the material illuminated. By inverting the formula for the resonant frequency, the permittivity of the material under test, averaged over the illuminated volume, can be estimated, thus allowing a map of this quantity to be reconstructed as a function of the sensor position. The results obtained are presented and discussed. Complementary measurements based on ultrasound transmission were not performed because of a delay in a previously scheduled field measurement campaign.

See at: CNR People


2009 Report Unknown

SIND - Descrizione del sistema
Chimenti M., Fantini E.
The report describes the functionality and the use of the H/S system SIND (System for Non-destructive Inspections), developed in the participation to the CNR Strategic Project SP1a. SIND is provided with probes, used for inspection made with ultrasonic waves, electric field and electromagnetic field. A graphic interface allows the user to navigate in a hierarchic menu, selecting processing modules, functions and procedures for different kinds of inspection. SIND offers a set of useful and easy to use tools for material characterization and anomalies or defect detection in objects under test.

See at: CNR People


2009 Report Unknown

Sampling the posterior density to estimate the CCA reconstruction error
Bedini L., Salerno E.
In addition to what we have done in [2008-B4-007] and [2009-B4-001], we propose here another strategy to estimate the reconstruction error affecting the harmonic version of CCA. We sample the CCA posterior density by a Metropolis-Hastings algorithm to find the ridge densities for the synchrotron and the dust spectral indices. On this basis, the densities of the individual source cross-spectra components can also be estimated. A Matlab code to sample the spectral indices is included.

See at: CNR People


2009 Report Unknown

Sonda per l'acquisizione di segnali a microonde
Gagliardi G.
The report describes the final prototype of a component of the H/S system SIND (System for Non-destructive Inspections), developed for inspections by means of electromagnetic fields. The described component is composed of a resonant antenna, working in the microwaves domain, and of several electronic circuits that are used for driving the antenna and for detecting the signal produced by the antenna when it is near to the object under test; information about the proximal layers of the object is obtained by analyzing the acquisition signals. The report describes the project criteria and the realization of the device; general specifics of the used electronic components are reported.

See at: CNR People