1,721,017 research outputs found
A Statistical Calibration Method based on Non-Linear Mixed Model for Affymetrix Probe Level Data
No full textGene expression microarrays allow a researcher to measure the simultaneous
response of thousands of genes to external conditions. Affymetrix GeneChipr expression
array technology has become a standard tool in medical research. Anyway, a preprocessing
step is usually necessary in order to obtain a gene expression measure. Aim of this
paper is to propose a calibration method to estimate the nominal concentration based on a
non-linear mixed model. This method is an enhancement of a method proposed in Mineo
et al. (2006). The relationship between raw intensities and concentration is obtained by
using the Langmuir isotherm theory
Modelling the background correction in microarray data analysis
No full textMicroarray technology has been adopted in many areas of biomedical research for quantitative and highly parallel measurements of gene expressions.
In this field, the high density oligonucleotide microarray technology is the most
used platform; in this platform oligonucleotides of 25 base pairs are used as probe
genes. Two types of probes are considered: perfect match (PM) and mismatch (MM)
probes. In theory, MM probes are used to quantify and remove two types of error:
optical noise and non specific binding. The correction of these two types of error is
known as background correction. Preprocessing is an essential step of the analysis
in which the intensity, read from each probe, is manipulated in order to obtain an
expression measure for each gene. In this paper, we introduce a new method for the
background correction by using a calibration approach based on a generalized linear
mixed model (GLMM)
A new proposal for microarray background correction by means of a GLMM
No full textLa tecnologia microarray ha il grosso pregio di misurare simultaneamente il
livello di espressione di migliaia di geni. All’elevata quantità d’informazione fornita da
un singolo chip si contrappone la necessità di un adeguato pretrattamento dei dati grezzi
al fine di ottenere una misura “affidabile” del livello di espressione genetico. Scopo del
lavoro è analizzare, attraverso un modello lineare generalizzato misto, il legame esistente
fra il livello d’intensità osservato ed il livello di concentrazione, attraverso l’utilizzo degli
esperimenti Spike-In forniti dall’Affymetrix. Si propone, quindi, un nuovo metodo per la
correzione del background
Prediction of the gene expression measure by means of a GLMM
No full textMicroarrays permit to scientists the screening of thousands of genes simultaneously to
determine, for example, whether those genes are active, hyperactive or silent in normal or
cancerous tissues. A primary task in microarray analysis is to obtain a good measure of the
gene expression that can be used for a so called higher level analysis. Different methods
have been proposed for high density oligonucleotide arrays (see Cope et al. (2004) for
a review). Aim of this paper is to obtain a new gene expression measure based on the
background correction model proposed by Mineo et al. (2006). The proposed method is
validated by means of a free available data-set called Spike-In133 experiment, where 42
genes are spiked in 42 arrays at known concentration from 0 to 512 pico-Molar (pM)
"Cytotoxicity and genotoxicity induced in human cells by commercial silica nanoparticles"
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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