53 research outputs found
Sviluppo di metodi per la gestione di razze autoctone italiane
The aim of this work is to give a review of official performance recordings performed by the Italian Breeders Association underlining the role of official recordings for all species and breeds of zoo-technical interest. Information and data collected with official performance recordings have allowed to analyze many aspects related to the conservation of autochthonous cattle breeds recorded at the Anagrafic Register of native cattle populations (R.A.B.), which are not subject to any national selection scheme, and to analyze some aspect of genetic improvement for autochthonous Herdbook breeds, focusing on the native Valdostana Red Pied breed. In the first chapter the Italian geographic distribution of heads and milk production has been described for year 2011. Evolution of productive and reproductive parameters are also analyzed for years 2004-2011 in large population breeds. A cluster analysis shows the degree of proximity between breeds recorded. This work concerns the identification of a (co)variance structure that allows a better interpretation of performance recording time series data by analyzing the phenotypic trend within breed in the period 2004-2011. Data show high concentration of official milk recording in the north of the country (79% herds and 86-87% of recorded cattle and milk production), the significant gap in milk production of Friesian over the other breeds, or in milk quality of Jersey, Brown Swiss and Valdostana Red Pied over the other breeds; whereas regarding to the fertility performances, Friesian has shown worst results, certainly due to its specialization in milk production. Focusing on cross breeding production and reproduction performance data, it can be noticed a similarity to Friesian performances, suggesting a most likely proximity to this breed than to other genetic types. The second chapter is a survey of the genetic variability of the sixteen autochthonous Italian cattle breeds recorded at the Anagrafic Register of native cattle populations (R.A.B.). The purpose was to analyze the genetic diversity of each population by the study of demographic and parentage index (i.e.: number of founders, number of ancestors, relatedness average between individuals, etc.) and the evaluation of inbreeding performance using a standard classification (Mc Parland, 2007). As a result, the effect of R.A.B. activity on autochthonous breeds conservation performed by the Italian Breeders Association was evaluated. A different scenario in pedigree completeness for different breeds has raised up from this work. In particular, Sardinian breeds (Sarda and Sardo Bruna breeds) and Agerolese have the most incomplete pedigrees while Tuscany breeds (Calvana, Garfagnina, Mucca Pisana e Pontremolese breeds), Varzese and Burlina breeds have deepest pedigrees. Regarding to the degree of relatedness average of each breed it can be seen that large size breeds (Sardo, Sardo Bruna, Sardo Modicana and Modicana breeds) have higher values of within herd average relatedness whereas have low values of within breed average relatedness (AR%), this is due to the rare use of artificial insemination and the infrequent exchange of bulls between farmers. The third chapter focuses on the development of a test-day model for genetic evaluation of autochthonous Valdostana Red Pied breed with the aim to review the current total lactation yield method versus a more sophisticated and accurate test-day yield method in order to give more efficient answers to selection needs. The work is a comparison of two different test-day models, one worked out by University of Padua and the other by the Research and Development office of Italian Breeders Association (A.I.A). In detail, the first comparison considered two different Repeatability TD models (below named as RP-TDm1 and RP-TDm2), afterwards the comparison has involved two different Random Regression TD models (below named as RR-TDm1 and RR-TDm2). The aim was to evaluate which model (1 Vs 2) and which method (RP Vs RR) were more appropriate for peculiar Valdostana Red Pied breed’s characteristics, and to build the best proposal to the Valdostana Red Pied National Breeders Association (A.Na.Bo.Ra.Va.). These comparisons were analyzed in terms of variance and covariance components estimation, then in terms of heritability for milk yield, fat percentage, protein percentage and somatic cell count and also in terms of Rank Correlation between the models. The work shows that random regression models can barely adapt to the reality of the Valdostana breed, which is characterized by a high level of calving seasonality and by the practice of summer pasture, which causes the rare number of test days in the tail of lactations. The two different methods (RP and RR) tested have both manifested a considerable difficulty in estimating the extremes of the lactation curve. Ali-Shaeffer model (RRm1), in fact, has produced a strong overestimation in early lactation phase for all traits, while the model based on Legendre’s polynomial (RRm2) produces a strong overestimation at the end of lactation phase. Instead, repeatability models (RPm) have produced comparable estimations between model 1 and model 2 and with results published in literature: milk yield 18-21% di h2, fat percentage 18% di h2, protein percentage 34-36% di h2 e SCS 10-12% di h2. The rank correlations of bulls or cows with greatest index accuracy were rather good for fat and protein indexes, the selection index IRC, which is based on the fat and protein indexes, has rank correlations between 87 and 94%. Rank correlations for milk genetic index were between 81 and 82%, these low values are worth of farther investigation
Stress-based performance evaluation of osseointegrated dental implants by finite-element simulation
In this paper biomechanical interaction between osseointegrated dental implants and bone is numerically investigated through 3D
linearly elastic finite-element analyses, when static functional loads occur. Influence of some mechanical and geometrical
parameters on bone stress distribution is highlighted and risk indicators relevant to critical overloading of bone are introduced. Insertions both in mandibular and maxillary molar segments are analyzed, taking into account different crestal bone loss configurations. Stress-based performances of five commercially-available dental implants are evaluated, demonstrating as the optimal choice of an endosseous implant is strongly affected by a number of shape parameters as well as by anatomy and mechanical properties of the site of placement. Moreover, effectiveness of some double-implant devices is addressed. The first one is relevant to a partially edentulous arch restoration, whereas other applications regard single-tooth restorations based on non-conventional endosteal mini-implants. Starting from computer tomography images and real devices, numerical models have been generated through a parametric algorithm based on a fully 3D approach. Furthermore, effectiveness and accuracy of finite-element simulations have been validated by
means of a detailed convergence analysis
Three-dimensional finite-element analysis of osseointegrated dental implants
In this paper the biomechanical interaction between osseointegrated dental implants and bone is investigated by numerical simulations. The influence of some mechanical and geometrical parameters on bone stress distributions is highlighted and some risk-measures relevant to critical overloading are furnished. Load transfer mechanisms of several dental implants are analyzed by means of linearly elastic finite-element analyses, when static functional loads occur. For a given implant the variation of its performance with the placement is investigated, considering insertions both in mandibular and maxillary molar segments. The mechanical properties of the bone regions (cortical and cancellous) are approximated with those of a type II bone and the geometry of crestal bone loss after an healing period is modelled. Five commercially-available dental implants are analyzed, demonstrating as the optimal choice of an endosseous implant is strongly affected by a number of shape parameters as well as by anatomy and mechanical properties of the site of placement. Numerical results clearly proof as a given implant device exhibits very different performance on mandibular or maxillary bone segments, resulting in higher compressive stresses when maxillary placement is experienced. Finally, the effectiveness of several multiple-implant restorative applications is investigated. The first one is related to a partially edentulous arch restoration, based on a double-implant device involving a retaining bar. Other applications regard single-tooth restorations based on non-conventional devices consisting in a mini-bar supported by two mini endosteal implants, possibly reproducing the natural roots orientation of a multiple-root tooth
Association of kidney disease measures with risk of renal function worsening in patients with type 1 diabetes
Background: Albuminuria has been classically considered a marker of kidney damage progression in diabetic patients and it is routinely assessed to monitor kidney function. However, the role of a mild GFR reduction on the development of stage 653 CKD has been less explored in type 1 diabetes mellitus (T1DM) patients. Aim of the present study was to evaluate the prognostic role of kidney disease measures, namely albuminuria and reduced GFR, on the development of stage 653 CKD in a large cohort of patients affected by T1DM. Methods: A total of 4284 patients affected by T1DM followed-up at 76 diabetes centers participating to the Italian Association of Clinical Diabetologists (Associazione Medici Diabetologi, AMD) initiative constitutes the study population. Urinary albumin excretion (ACR) and estimated GFR (eGFR) were retrieved and analyzed. The incidence of stage 653 CKD (eGFR < 60 mL/min/1.73 m2) or eGFR reduction > 30% from baseline was evaluated. Results: The mean estimated GFR was 98 \ub1 17 mL/min/1.73m2 and the proportion of patients with albuminuria was 15.3% (n = 654) at baseline. About 8% (n = 337) of patients developed one of the two renal endpoints during the 4-year follow-up period. Age, albuminuria (micro or macro) and baseline eGFR < 90 ml/min/m2 were independent risk factors for stage 653 CKD and renal function worsening. When compared to patients with eGFR > 90 ml/min/1.73m2 and normoalbuminuria, those with albuminuria at baseline had a 1.69 greater risk of reaching stage 3 CKD, while patients with mild eGFR reduction (i.e. eGFR between 90 and 60 mL/min/1.73 m2) show a 3.81 greater risk that rose to 8.24 for those patients with albuminuria and mild eGFR reduction at baseline. Conclusions: Albuminuria and eGFR reduction represent independent risk factors for incident stage 653 CKD in T1DM patients. The simultaneous occurrence of reduced eGFR and albuminuria have a synergistic effect on renal function worsening
Ragionamenti varii di Lorenzo Capelloni, sobra essempii: con accidenti misti, seguiti, et occorsi, non mai veduti in luce...
En port. grab. xil. esc. ducalMarca tip. al finApostillas marginalesColofĂłnEnc. HolandesaSign.: a-d4, A-Z4, AA
Mechanical characterization of human dentin: a critical review
In the last years, several experimental techniques have been improved to measure mechanical properties of human dentin. Dentin exhibits a behavior like a functionally graded material with properties dependent on tubule density and orientation. This work describes and critically analyzes the elastic, anelastic and plastic characteristics of dentin on the basis of scientific literature, in particular data of Youngs modulus, shear modulus, Poissons ratio, yield and ultimate stress, hardness, fatigue, fracture toughness, creep, stress relaxation and damping have been considered. Finally, a new indentation technique (FIMEC test) is proposed to characterize the mechanical properties of dentin on a local scale.</jats:p
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