Ursula Gonzales-barron - Academia.edu (original) (raw)

Papers by Ursula Gonzales-barron

Research paper thumbnail of State-of-the-Art of Livestock Movement Monitoring Using Computer Vision Systems

Zenodo (CERN European Organization for Nuclear Research), Nov 20, 2006

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Research paper thumbnail of Statistical and spectral texture analysis methods for discrimination of bread crumb images

13th World Congress of Food Science & Technology, 2006

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Research paper thumbnail of Discrimination of crumb grain visual appearance of organic and non-organic bread loaves by image texture analysis

Journal of Food Engineering, Feb 1, 2008

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Research paper thumbnail of The use of meta-analytical tools in risk assessment for food safety

Food Microbiology, Jun 1, 2011

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Research paper thumbnail of A Bayesian approach to estimating the uncertainty in the distribution of Cronobacter spp. in powdered infant formula arising from microbiological criteria test outcomes

Microbial Risk Analysis, Dec 1, 2016

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Research paper thumbnail of A comparison between the discrete Poisson-gamma and Poisson-lognormal distributions to characterise microbial counts in foods

Food Control, Aug 1, 2011

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Research paper thumbnail of Use of a Poisson-gamma model to assess the performance of the EC process hygiene criterion for Enterobacteriaceae on Irish sheep carcasses

Food Control, May 1, 2012

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Research paper thumbnail of Review of biometric and electronic systems of livestock identification

Zenodo (CERN European Organization for Nuclear Research), Sep 27, 2005

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Research paper thumbnail of Count data distributions and their zero-modified equivalents as a framework for modelling microbial data with a relatively high occurrence of zero counts

International Journal of Food Microbiology, 2010

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Research paper thumbnail of Modelling the concentration of Salmonella in Irish fresh pork sausage from most probable number (MPN) data

As part of a second-order model quantifying the risk of salmonellosis from consumption of fresh p... more As part of a second-order model quantifying the risk of salmonellosis from consumption of fresh pork sausage in Ireland, a separate sub-model was conducted to estimate the initial concentration of Salmonella Typhimurium in fresh pork sausage at retail using most probable number (MPN) results. This approach provided a more informed second-order distribution of CFU/g that would have been possible by the ordinary practice of fitting a distribution to the MPN/g.

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Research paper thumbnail of Fractal texture analysis of bread crumb digital images

European Food Research and Technology, Feb 14, 2007

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Research paper thumbnail of A longitudinal study of the effect of time on the matching performance of a retinal recognition system for lambs

Computers and Electronics in Agriculture, Dec 1, 2008

... To this aim, a longitudinal study was devised to observe the evolution of matching scores (ms... more ... To this aim, a longitudinal study was devised to observe the evolution of matching scores (ms) of lamb retinal images (n = 38) acquired from 1 to 22 weeks after birth. ... 2. Materials and methods. 2.1. Longitudinal study of lamb's retinal images. ...

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Research paper thumbnail of A comparison of seven thresholding techniques with the k-means clustering algorithm for measurement of bread-crumb features by digital image analysis

Journal of Food Engineering, May 1, 2006

... Image segmentation is the first step of image analysis which aims at either a description of ... more ... Image segmentation is the first step of image analysis which aims at either a description of an image or a classification. Hundreds of segmentation techniques are present in the literature and almost all are ad hoc in nature (Fu & Mui, 1981). ...

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Research paper thumbnail of An alternative framework to conduct inferential statistics for low microbial counts in foods: the poisson-gamma regression

The objective of this article was to compare four Poisson-gamma regression models to assess the e... more The objective of this article was to compare four Poisson-gamma regression models to assess the effect of chilling on the concentration of coliforms from beef carcasses. A total of 600 carcasses were sampled before and after chilling at eight large Irish abattoirs, and the total coliforms were determined. With a coded variable (pre-chill/post-chill) as treatment, and extracting the variability of batches nested in abattoirs, random-effects models confirmed that chilling had a decreasing effect on the overall recovery of coliforms. Furthermore, the expected coliforms concentrations on pre-chill and post-chill carcasses were estimated on a CFU/cm2 scale, as well as their between-batch variability. This study introduced an alternative conceptual framework that can find interesting applications in stochastic risk assessment and in the design of more efficient sampling plans.info:eu-repo/semantics/publishedVersio

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Research paper thumbnail of Omnibus Modeling of Listeria monocytogenes Growth Rates at Low Temperatures

Foods

Listeria monocytogenes is a pathogen of considerable public health importance with a high case fa... more Listeria monocytogenes is a pathogen of considerable public health importance with a high case fatality. L. monocytogenes can grow at refrigeration temperatures and is of particular concern for ready-to-eat foods that require refrigeration. There is substantial interest in conducting and modeling shelf-life studies on L. monocytogenes, especially relating to storage temperature. Growth model parameters are generally estimated from constant-temperature growth experiments. Traditionally, first-order and second-order modeling (or primary and secondary) of growth data has been done sequentially. However, omnibus modeling, using a mixed-effects nonlinear regression approach, can model a full dataset covering all experimental conditions in one step. This study compared omnibus modeling to conventional sequential first-order/second-order modeling of growth data for five strains of L. monocytogenes. The omnibus model coupled a Huang primary model for growth with secondary models for growth ...

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Research paper thumbnail of Modelling the inhibitory effect of LAB on L. monocytogenes and Enterobacteriaceae in a fermented sausage during ripening

Earlier research has shown that the survivability of Enterobacteriaceae (ENT) and L. monocytogene... more Earlier research has shown that the survivability of Enterobacteriaceae (ENT) and L. monocytogenes (LM) in a Portuguese fermented sausage (linguiça) decreases during the ripening stage, and that such inhibition arises from the adverse conditions caused by the competition with autochthonous lactic acid bacteria (LAB) and the progressively lower water activity and pH. The objective of this work was to mathematically characterise the competition or interactions between LAB, LM and ENT that takes place in fermenting linguiça during ripening.info:eu-repo/semantics/publishedVersio

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Research paper thumbnail of State-of-the-Art of Livestock Movement Monitoring Using Computer Vision Systems

Whitepaper of The BioTrack Project: "Development of a protocol for biometric-based animal tr... more Whitepaper of The BioTrack Project: "Development of a protocol for biometric-based animal tracking and tracing". Biosystems Engineering, University College Dublin, Ireland.

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Research paper thumbnail of Poisson-Gamma and Poisson-Lognormal models for the characterisation of within-batch and between-batch variability in microbial counts in foods

In modelling risk management strategies (i.e., with in-lot batch testing, statistical process con... more In modelling risk management strategies (i.e., with in-lot batch testing, statistical process control), two basic assumptions have been normally made: that the true concentration of microorganisms are log-normally distributed within a batch, and that the variance of the samples is the same for a little or highly contaminated lot. These assumptions were evaluated by characterisin g the between-batch and within-batch variability in microbial counts within a heterogeneous Poisson the oretical interpretation; this is a gamma or a logno rmal true or population distribution for the unknown microbial concentration and a Pois s n measurement distribution that produces a discrete Poisson-gamma or a Poisson -lognormal distribution of observed plate counts. Two variants of random-effects regressions based o n the Poisson-gamma (m,1/k) and the Poissonlognormal (μ,σ) models were fitted to two microbial data sets of TVC (high counts) and Escherichia coli (low counts) on pre-chill beef carcasses s...

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Research paper thumbnail of Use of a Poisson-Gamma regression model to assess the process hygiene criterion for Enterobacteriaceae on Irish sheep carcasses

The new Poisson-gamma modelling framework for low b acterial counts has been used to characterise... more The new Poisson-gamma modelling framework for low b acterial counts has been used to characterise withi nbatch and between-batch variability in Enterobacteriaceae in pre-chill sheep carcasses using counts data from five abattoirs sampled on four different occas ion . The negative correlation between the mean and dispersion parameters of the within-batch true dist ribu ions (gamma) was accounted by a correlated ran omeffects model. Since no assumption of within-batch constant variance was followed, all probability estimations could be performed with confidence inte rvals arising from the variability in the within-ba tch spread given a certain within-batch mean. The model was used in the assessment of the actual performan ce of the process hygiene criterion set by EC 2073/2005, and estimated that only 0.93% (95% CI: 0-4.08%) of the batches of pre-chill sheep carcasses produced in Ir eland would be found to be above the m limit of 1.5 log CFU/cm (~88 CFU/cm) and no batches would be fou...

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Research paper thumbnail of Food additives composition of a Portuguese traditional fermented sausage (chouriço) after drying

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Research paper thumbnail of State-of-the-Art of Livestock Movement Monitoring Using Computer Vision Systems

Zenodo (CERN European Organization for Nuclear Research), Nov 20, 2006

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Research paper thumbnail of Statistical and spectral texture analysis methods for discrimination of bread crumb images

13th World Congress of Food Science & Technology, 2006

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Discrimination of crumb grain visual appearance of organic and non-organic bread loaves by image texture analysis

Journal of Food Engineering, Feb 1, 2008

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Research paper thumbnail of The use of meta-analytical tools in risk assessment for food safety

Food Microbiology, Jun 1, 2011

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Research paper thumbnail of A Bayesian approach to estimating the uncertainty in the distribution of Cronobacter spp. in powdered infant formula arising from microbiological criteria test outcomes

Microbial Risk Analysis, Dec 1, 2016

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Research paper thumbnail of A comparison between the discrete Poisson-gamma and Poisson-lognormal distributions to characterise microbial counts in foods

Food Control, Aug 1, 2011

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Research paper thumbnail of Use of a Poisson-gamma model to assess the performance of the EC process hygiene criterion for Enterobacteriaceae on Irish sheep carcasses

Food Control, May 1, 2012

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Research paper thumbnail of Review of biometric and electronic systems of livestock identification

Zenodo (CERN European Organization for Nuclear Research), Sep 27, 2005

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Research paper thumbnail of Count data distributions and their zero-modified equivalents as a framework for modelling microbial data with a relatively high occurrence of zero counts

International Journal of Food Microbiology, 2010

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Modelling the concentration of Salmonella in Irish fresh pork sausage from most probable number (MPN) data

As part of a second-order model quantifying the risk of salmonellosis from consumption of fresh p... more As part of a second-order model quantifying the risk of salmonellosis from consumption of fresh pork sausage in Ireland, a separate sub-model was conducted to estimate the initial concentration of Salmonella Typhimurium in fresh pork sausage at retail using most probable number (MPN) results. This approach provided a more informed second-order distribution of CFU/g that would have been possible by the ordinary practice of fitting a distribution to the MPN/g.

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Research paper thumbnail of Fractal texture analysis of bread crumb digital images

European Food Research and Technology, Feb 14, 2007

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Research paper thumbnail of A longitudinal study of the effect of time on the matching performance of a retinal recognition system for lambs

Computers and Electronics in Agriculture, Dec 1, 2008

... To this aim, a longitudinal study was devised to observe the evolution of matching scores (ms... more ... To this aim, a longitudinal study was devised to observe the evolution of matching scores (ms) of lamb retinal images (n = 38) acquired from 1 to 22 weeks after birth. ... 2. Materials and methods. 2.1. Longitudinal study of lamb's retinal images. ...

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Research paper thumbnail of A comparison of seven thresholding techniques with the k-means clustering algorithm for measurement of bread-crumb features by digital image analysis

Journal of Food Engineering, May 1, 2006

... Image segmentation is the first step of image analysis which aims at either a description of ... more ... Image segmentation is the first step of image analysis which aims at either a description of an image or a classification. Hundreds of segmentation techniques are present in the literature and almost all are ad hoc in nature (Fu & Mui, 1981). ...

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Research paper thumbnail of An alternative framework to conduct inferential statistics for low microbial counts in foods: the poisson-gamma regression

The objective of this article was to compare four Poisson-gamma regression models to assess the e... more The objective of this article was to compare four Poisson-gamma regression models to assess the effect of chilling on the concentration of coliforms from beef carcasses. A total of 600 carcasses were sampled before and after chilling at eight large Irish abattoirs, and the total coliforms were determined. With a coded variable (pre-chill/post-chill) as treatment, and extracting the variability of batches nested in abattoirs, random-effects models confirmed that chilling had a decreasing effect on the overall recovery of coliforms. Furthermore, the expected coliforms concentrations on pre-chill and post-chill carcasses were estimated on a CFU/cm2 scale, as well as their between-batch variability. This study introduced an alternative conceptual framework that can find interesting applications in stochastic risk assessment and in the design of more efficient sampling plans.info:eu-repo/semantics/publishedVersio

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Research paper thumbnail of Omnibus Modeling of Listeria monocytogenes Growth Rates at Low Temperatures

Foods

Listeria monocytogenes is a pathogen of considerable public health importance with a high case fa... more Listeria monocytogenes is a pathogen of considerable public health importance with a high case fatality. L. monocytogenes can grow at refrigeration temperatures and is of particular concern for ready-to-eat foods that require refrigeration. There is substantial interest in conducting and modeling shelf-life studies on L. monocytogenes, especially relating to storage temperature. Growth model parameters are generally estimated from constant-temperature growth experiments. Traditionally, first-order and second-order modeling (or primary and secondary) of growth data has been done sequentially. However, omnibus modeling, using a mixed-effects nonlinear regression approach, can model a full dataset covering all experimental conditions in one step. This study compared omnibus modeling to conventional sequential first-order/second-order modeling of growth data for five strains of L. monocytogenes. The omnibus model coupled a Huang primary model for growth with secondary models for growth ...

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Research paper thumbnail of Modelling the inhibitory effect of LAB on L. monocytogenes and Enterobacteriaceae in a fermented sausage during ripening

Earlier research has shown that the survivability of Enterobacteriaceae (ENT) and L. monocytogene... more Earlier research has shown that the survivability of Enterobacteriaceae (ENT) and L. monocytogenes (LM) in a Portuguese fermented sausage (linguiça) decreases during the ripening stage, and that such inhibition arises from the adverse conditions caused by the competition with autochthonous lactic acid bacteria (LAB) and the progressively lower water activity and pH. The objective of this work was to mathematically characterise the competition or interactions between LAB, LM and ENT that takes place in fermenting linguiça during ripening.info:eu-repo/semantics/publishedVersio

Bookmarks Related papers MentionsView impact

Research paper thumbnail of State-of-the-Art of Livestock Movement Monitoring Using Computer Vision Systems

Whitepaper of The BioTrack Project: "Development of a protocol for biometric-based animal tr... more Whitepaper of The BioTrack Project: "Development of a protocol for biometric-based animal tracking and tracing". Biosystems Engineering, University College Dublin, Ireland.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Poisson-Gamma and Poisson-Lognormal models for the characterisation of within-batch and between-batch variability in microbial counts in foods

In modelling risk management strategies (i.e., with in-lot batch testing, statistical process con... more In modelling risk management strategies (i.e., with in-lot batch testing, statistical process control), two basic assumptions have been normally made: that the true concentration of microorganisms are log-normally distributed within a batch, and that the variance of the samples is the same for a little or highly contaminated lot. These assumptions were evaluated by characterisin g the between-batch and within-batch variability in microbial counts within a heterogeneous Poisson the oretical interpretation; this is a gamma or a logno rmal true or population distribution for the unknown microbial concentration and a Pois s n measurement distribution that produces a discrete Poisson-gamma or a Poisson -lognormal distribution of observed plate counts. Two variants of random-effects regressions based o n the Poisson-gamma (m,1/k) and the Poissonlognormal (μ,σ) models were fitted to two microbial data sets of TVC (high counts) and Escherichia coli (low counts) on pre-chill beef carcasses s...

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Research paper thumbnail of Use of a Poisson-Gamma regression model to assess the process hygiene criterion for Enterobacteriaceae on Irish sheep carcasses

The new Poisson-gamma modelling framework for low b acterial counts has been used to characterise... more The new Poisson-gamma modelling framework for low b acterial counts has been used to characterise withi nbatch and between-batch variability in Enterobacteriaceae in pre-chill sheep carcasses using counts data from five abattoirs sampled on four different occas ion . The negative correlation between the mean and dispersion parameters of the within-batch true dist ribu ions (gamma) was accounted by a correlated ran omeffects model. Since no assumption of within-batch constant variance was followed, all probability estimations could be performed with confidence inte rvals arising from the variability in the within-ba tch spread given a certain within-batch mean. The model was used in the assessment of the actual performan ce of the process hygiene criterion set by EC 2073/2005, and estimated that only 0.93% (95% CI: 0-4.08%) of the batches of pre-chill sheep carcasses produced in Ir eland would be found to be above the m limit of 1.5 log CFU/cm (~88 CFU/cm) and no batches would be fou...

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Research paper thumbnail of Food additives composition of a Portuguese traditional fermented sausage (chouriço) after drying

Bookmarks Related papers MentionsView impact