Livio Corain

Age estimation in the Mediterranean bottlenose dolphin Tursiops truncatus (Montagu 1821) by bone density of the thoracic limb

The determination of age is an important step in defining the life history traits of individuals and populations. Age determination of odontocetes is mainly based on counting annual growth layer groups in the teeth. However, this useful method is always invasive, requiring the cutting of at least one tooth, and sometimes the results are difficult to interpret. Based on the concept that bone matrix is constantly deposited throughout life, we analysed the bone mineral density of the arm and forearm of a series of bottlenose dolphins (Tursiops truncatus, Montagu 1821) stranded along the Italian coast of the Adriatic Sea or maintained in confined waters. The bone mineral density values we obtained were evaluated as possible age predictors of the Mediterranean population of this species, considering age as determined by counting growth layer groups in sections of the teeth and the total body length of the animal as references. Comparisons between left and right flipper showed no difference. Our results show that bone mineral density values of the thoracic limb are indeed reliable age predictors in Tursiops truncatus. Further investigations in additional odontocete species are necessary to provide strong evidence of the reliability of bone mineral density as an indicator of growth and chronological wear and tear in toothed‐whales.

A Non-parametric Method for Defining a Global Preference Ranking of Industrial Products

Abstract Although experimentation is a crucial stage in the process of research and development of industrial products, no satisfactory procedure is available to deal with the common but rather important industrial problem of defining a preference ranking among all the studied product prototypes on the basis of performances. In this paper we propose a two-stage non-parametric procedure in which we firstly perform a set of C-sample testing procedures, followed by multiple comparisons, in this way evaluating a set of partial preference rankings, and secondly synthesise the partial rankings by combining them into a global ranking that provides a general product preference rule. The proposed method is particularly useful in the context of industrial experimentation and offers several advantages such as effectiveness, high flexibility and practical adherence to real problems where preference ranking is a natural goal.

Long-term results of sequential vein coronary artery bypass grafting compared with totally arterial myocardial revascularization: a propensity score-matched follow-up study

OBJECTIVES The aim of the study was to analyse the early and long-term outcomes of a consecutive series of patients who underwent sequential coronary artery bypass grafting (CABG) and to compare them with a matched population of totally arterial revascularized patients. METHODS From January 1994 to December 1996, 209 patients underwent total arterial myocardial revascularization at our institution [arterial (ART) group]. In the same period, 2097 patients underwent CABG with left internal thoracic artery on left anterior descending and great saphenous vein on the right and circumflex branches sequentially [sequential vein (SV) group]. The propensity score methodology was used to obtain risk-adjusted outcome comparisons between the two groups (209 vs 243 patients in the ART group and SV group, respectively). RESULTS In-hospital mortality was 1% in the ART group and 0.4% in the SV group (P = 0.86). Mean follow-up was 14 ± 4 years. Long-term survival was comparable among the two study groups [actuarial 5- and 15-year survival rates were 97 vs 93% and 82 vs 79% in the ART group and the SV group, respectively (P = 0.29)]. At follow-up, recurrence of angina (17 vs 18%; P = 0.99), acute myocardial infarction (MI) (3 vs 5%; P = 0.72) and repeated percutaneous coronary intervention (19 vs 21%; P = 0.69) were similar in the ART group compared with the SV group. In the Cox regression analysis, type of revascularization was not an independent predictor of any long-term outcomes (death or major adverse cardiac events). In asymptomatic patients, exercise stress test at follow-up was comparable between the two groups (P = 0.14). CONCLUSIONS Sequential vein CABG appears to have good early and long-term clinical outcomes. Also, early and long-term incidence of acute MI was not significantly higher in the SV group. However, further studies with a larger population are warranted in order to confirm the present results.

Nonparametric Hypothesis Testing: Rank and Permutation Methods with Applications in R

Description: A novel presentation of rank and permutation tests, with accessible guidance to applications in R Nonparametric testing problems are frequently encountered in many scientific disciplines, such as engineering, medicine and the social sciences. This book summarizes traditional rank techniques and more recent developments in permutation testing as robust tools for dealing with complex data with low sample size. Key Features: Examines the most widely used methodologies of nonparametric testing. Includes extensive software codes in R featuring worked examples, and uses real case studies from both experimental and observational studies. Presents and discusses solutions to the most important and frequently encountered real problems in different fields. Features a supporting website containing all of the data sets examined in the book along with ready to use R software codes. Nonparametric Hypothesis Testing combines an up to date overview with useful practical guidance to applications in R, and will be a valuable resource for practitioners and researchers working in a wide range of scientific fields including engineering, biostatistics, psychology and medicine.

Measurements of indoor environmental conditions in Italian classrooms and their impact on children’s comfort

This study evaluates the indoor environmental conditions and children’s comfort levels in 8 classrooms in three Italian primary schools. It is a development of a pilot study previously carried out by the authors in other educational buildings. Spot and long-term measurements were made to evaluate microclimatic conditions (i.e. air temperature, relative humidity, CO2 concentration, and illuminance). A questionnaire, distributed three times, investigated the students’ perception of thermal and lighting comfort, their satisfaction with building-related factors, and their interactions with the environment. Predicted mean vote and predicted percentage dissatisfied indexes were calculated and an adaptive approach was also applied, but their results did not correspond to the students’ subjective evaluation of thermal comfort. An innovative multivariate ranking method was developed as a possible tool to assess building stocks in order to establish priorities for repair, maintenance, and refurbishment. The problem which the students complained about the most was the thermal comfort in the hot season and solar penetration. Moreover, the school with the worst microclimatic conditions was also judged the worst for building-related and psychological factors.

New insights on permutation approach for hypothesis testing on functional data

The permutation approach for testing the equality of distributions and thereby comparing two populations of functional data has recently received increasing attention thanks to the flexibility of permutation tests to handle complex testing problems. The purpose of this work is to present some new insights in the context of nonparametric inference on functional data using the permutation approach, more specifically we formally show the equivalence of some permutation procedures proposed in the literature and we suggest the use of the permutation and combination-based approach within the basis function approximation layout. Validation of theoretical results is shown by simulation studies.

Expression and localization of aromatase P450AROM, estrogen receptor-α, and estrogen receptor-β in the developing fetal bovine frontal cortex

The enzyme aromatase (P450(AROM)) converts testosterone (T) into 17-β estradiol (E(2)) and is crucial for the control of development of the central nervous system during ontogenesis. The effects of E(2) in various brain areas are mediated by the estrogen receptor alpha (ER-α) and the estrogen receptor beta (ER-β). During fetal development, steroids are responsible for the sexual differentiation of the hypothalamus. Estrogens are also able to exert effects in other brain areas of the fetus including the frontal cortex, where they act through estrogen receptors (ERs) modulating cognitive function and affective behaviors. In this study we have determined the expression profiles of P450(AROM) and ERs in the fetal bovine frontal cortex by quantitative Real-Time PCR (qRT-PCR) throughout the prenatal development. The data show that the patterns of expression of both ERs are strongly correlated during pregnancy and increase in the last stage of gestation. On the contrary, the expression of P450(AROM) has no correlation with ERs expression and is not developmentally regulated. Moreover, we performed immunochemical studies showing that fetal neurons express P450(AROM) and the ERs. P450(AROM) is localized in the cytoplasm and only seldom present in the fine extensions of the cells; ER-α is detected predominantly in the soma whereas ER-β is only present in the nucleus of a few cells. This study provides new data on the development of the frontal cortex in a long gestation mammal with a large convoluted brain.

Neurocognitive Effects in Welders Exposed to Aluminium: An Application of the NPC Test and NPC Ranking Methods

The aim of this study is to investigate the effects of exposure to aluminium on the cognitive sphere in a group of welders. Given the intrinsic complexity of the neurocognitive sphere, three different psychomotor variables were used for its investigation allowing the resulting problem to be naturally modelized into a multivariate framework and solved by a nonparametric combination of permutation tests (NPC test). In order to make the treated and control groups comparable, we also stratified the samples on the basis of a risk index that estimates the combined action of biological age and exposure time. Despite the fact that studies in the literature have reached conflicting results, our study highlights a significant drop in attention and memory performances in individuals exposed to aluminium. Finally, we identify a global criterion that summarises the information on the neurocognitive state by applying the nonparametric combination of dependent rankings method (NPC ranking).

Advantages of the Closed Testing Method in Multiple Comparisons Procedures

This article deals with the use of the Closed Testing approach in Multiple Comparison Procedures (MCPs). MCPs occur when after rejection of a global hypothesis of no effect of a given treatment, a set of pairwise comparisons between levels of that treatment are performed in order to find out significant differences between levels. Given a set of partial hypotheses, such as the pairwise comparisons of an MCP, the Closed Testing approach concentrates on testing the family of all the non empty intersections of these partial hypotheses. The results of our simulation study highlight the advantages of closed testing methods and prove that they are more powerful than other classic MCPs controlling the FWER.

A Critical Review and a Comparative Study on Conditional Permutation Tests for Two-Way ANOVA

Two-way ANOVA methodology is surely one of the most important models in the framework of the experimental design theory, as suggested by the great number of proposed solutions given in literature. Among these, some solutions are nonparametric and particularly, thanks to the availability of modern powerful computing equipments, those based on conditional on observations permutation test have gained great interest. The aim of this work is to present and compare such proposals and to illustrate their possible advantages and disadvantages when applied to some real data-sets.