Enrico Fabrizi

Biodiversity among Lactobacillus helveticus Strains Isolated from Different Natural Whey Starter Cultures as Revealed by Classification Trees

ABSTRACT Lactobacillus helveticus is a homofermentative thermophilic lactic acid bacterium used extensively for manufacturing Swiss type and aged Italian cheese. In this study, the phenotypic and genotypic diversity of strains isolated from different natural dairy starter cultures used for Grana Padano, Parmigiano Reggiano, and Provolone cheeses was investigated by a classification tree technique. A data set was used that consists of 119 L. helveticus strains, each of which was studied for its physiological characters, as well as surface protein profiles and hybridization with a species-specific DNA probe. The methodology employed in this work allowed the strains to be grouped into terminal nodes without difficult and subjective interpretation. In particular, good discrimination was obtained between L. helveticus strains isolated, respectively, from Grana Padano and from Provolone natural whey starter cultures. The method used in this work allowed identification of the main characteristics that permit discrimination of biotypes. In order to understand what kind of genes could code for phenotypes of technological relevance, evidence that specific DNA sequences are present only in particular biotypes may be of great interest.

Hierarchical Bayes multivariate estimation of poverty rates based on increasing thresholds for small domains

A model-based small area method for calculating estimates of poverty rates based on different thresholds for subsets of the Italian population is proposed. The subsets are obtained by cross-classifying by household type and administrative region. The suggested estimators satisfy the following coherence properties: (i) within a given area, rates associated with increasing thresholds are monotonically increasing; (ii) interval estimators have lower and upper bounds within the interval (0, 1); (iii) when a large domain-specific sample is available the small area estimate is close to the one obtained using standard design-based methods; (iv) estimates of poverty rates should also be produced for domains for which there is no sample or when no poor households are included in the sample. A hierarchical Bayesian approach to estimation is adopted. Posterior distributions are approximated by means of MCMC computation methods. Empirical analysis is based on data from the 2005 wave of the EU-SILC survey.

Pre-school children have better spoken language when early implanted

OBJECTIVES The objectives of this study were: (1) to investigate the effect of age at cochlear implantation (CI) on vocabulary development; (2) to evaluate the age effect at CI surgery on the syntactic development; and (3) to examine the role of gender, age at first diagnosis and maternal education level on spoken language development. MATERIAL AND METHODS Retrospective study. Thirty children with congenital severe- to -profound sensorineural hearing loss (SNHL) were sampled. They were diagnosed and fitted with hearing aids through six months of age. They were implanted between 8 and 17 months of age. The MacArthur-Bates Communicative Development Inventory (MCDI) was administrated at the age of 36 months. The total productive vocabulary (word number raw score), the mean length of utterance (M3L) and the sentences complexity were analysed. RESULTS The average word number raw score was 566.3 for the children implanted before 12 months of age versus 355 for those implanted later. The M3L was 8.3 for those implanted under 1 year versus 4.2 of those implanted later. The average sentences complexity was 82.3% for those receiving CI before 12 months, while it was 24.4% for those underwent at CI after 12 months. Regression analysis revealed a highly significant and negative linear effect of age at CI surgery on all outcomes. Females had better outcomes. Age at diagnosis was not correlated with the linguistic results. The mothers education level had a positive significant effect on sentences complexity. CONCLUSION The CI in pre-school children with SNHL implanted under 1 year has a positive effect on spoken language. Females seem to have better linguistic results. Finally high maternal educational level appears to have some positive effect on language development.

Outlier robust model-assisted small area estimation

Small area estimation with M-quantile models was proposed by Chambers and Tzavidis (). The key target of this approach to small area estimation is to obtain reliable and outlier robust estimates avoiding at the same time the need for strong parametric assumptions. This approach, however, does not allow for the use of unit level survey weights, making questionable the design consistency of the estimators unless the sampling design is self-weighting within small areas. In this paper, we adopt a model-assisted approach and construct design consistent small area estimators that are based on the M-quantile small area model. Analytic and bootstrap estimators of the design-based variance are discussed. The proposed estimators are empirically evaluated in the presence of complex sampling designs.

Bayesian Estimation of Log-Normal Means with Finite Quadratic Expected Loss

The log-normal distribution is a popular model in biostatistics and other fields of statistics. Bayesian inference on the mean and median of the dis- tribution is problematic because, for many popular choices of the prior for the variance (on the log-scale) parameter, the posterior distribution has no finite mo- ments, leading to Bayes estimators with infinite expected loss for the most common choices of the loss function. We propose a generalized inverse Gaussian prior for the variance parameter, that leads to a log-generalized hyperbolic posterior, for which it is easy to calculate quantiles and moments, provided that they exist. We derive the constraints on the prior parameters that yield finite posterior moments of or- der r. We investigate the choice of prior parameters leading to Bayes estimators with optimal frequentist mean square error. For the estimation of the lognormal mean we show, using simulation, that the Bayes estimator under quadratic loss compares favorably in terms of frequentist mean square error to known estimators.

Narrative abilities in early implanted children

To investigate the effect of age at cochlear implant activation on oral narrative ability in children implanted before 2.5 years of age and to examine the role of other variables (gender, parental education level, stimulation modality) in narrative skills.

Unemployment outflows: the relevance of gender and marital status in Italy and Spain

Purpose - – The purpose of this paper is to shed light on transitions from the state of unemployment to that of employment and of inactivity in Italy and Spain. Design/methodology/approach - – First, the paper investigates the determinants of unemployment outflows in these two Mediterranean labour markets. Then, the paper examines discrepancies and similarities between specific outflow determinants, especially the interactions between gender and marital status, by comparing results obtained across countries. Findings - – The findings of the paper suggest that gender and marital status influence the probability of unemployment outflows in both countries, although not in the same way, especially with reference to marital status. Discrepancies also emerge in relation to the role of geographical area of residence. Originality/value - – International comparisons of unemployment outflows are rather new in the literature, and as far as we know none have been performed using European Union Statistics on Income and Living Conditions data. Further, although studies quite often examine the issue of gender-related labour mobility using the European Community Household Panel survey that took place in the 1990s (Arulampalam

Small area estimation of the Gini concentration coefficient

The Gini coefficient is a popular concentration measure often used in the analysis of economic inequality. Estimates of this index for small regions may be useful to properly represent inequalities within local communities. However, the small area estimation for the Gini coefficient has not been thoroughly investigated. A method based on area level models, thereby avoiding the assumption of the availability of Census data at the micro level, is proposed. A modified design based estimator for the coefficient with reduced small sample bias is suggested as input for the small area model, while a hierarchical Beta mixed regression model is introduced to combine survey data and auxiliary information. The methodology is illustrated by means of an example based on Italian data from the European Union Survey on Income and Living Conditions.

Production of infant scale evaluation (PRISE) in Italian normal hearing children: a validation study.

OBJECTIVES Parental questionnaires are important tools in the evaluation of auditory and language skills of very young children affected by sensorineural hearing loss. One of these instruments is the Production on Infant Scale Evaluation (PRISE). The purposes of this study were to adapt and validate the PRISE on Italian children with normal hearing; and to obtain normative data. METHODS A back translation technique was used to adapt the Italian version of PRISE. The PRISE was submitted to parents of 234 normal children aged between 3 and 18 months of life. All of them passed local universal newborn hearing screenings and they presented no audiological risk factors. RESULTS The PRISE internal reliability (Cronbachs alpha) was 0.87. Split-half reliability indexes were λ(4) = 0.89 and λ(6) = 0.89. Corrected item-total correlation coefficients were significant for all items. The correlation of PRISE with a modified Infant Toddler Meaningful Auditory Integration Scale (IT-MAIS), collected for convergent validity measurement purposes, was good (r = 0.743). A positive correlation of PRISE scores with age was found, reflecting on the age-dependence of pre-verbal skills. CONCLUSION These findings demonstrate high reliability and convergent validity of the Italian PRISE version. This questionnaire constitutes a robust tool for assessing early language development in infants and toddlers with normal hearing. It seems particularly sensitive to the normal language development in the first years of life, which can be very useful for early rehabilitation of hearing loss.

Social conversational skills development in early implanted children

Social conversational skills are a salient aspect of early pragmatic development in young children. These skills include two different abilities, assertiveness and responsiveness. This study investigated the development of these abilities in early implanted children and their relationships with lexical development and some language‐sensitive variables.