A hybrid-Trefftz finite element for the postbuckling analysis of composite shell structures

A corotational mixed flat shell element for the geometrically nonlinear analysis of laminated composite structures is presented. The stress interpolation is derived from the linear elastic solution for symmetric composite materials.Displacement and rotation fields are only assumed along the contour of the element. As such, all the operators are efficiently obtained through analytical contour integration. The geometrical nonlinearity is introduced by means of a corotational formulation. The proposed finite element, named MISS-4c, proves to be locking free and shows no rank defectiveness. A multimodal Koiter's algorithm is used to obtain the initial postbuckling response. Results show good accuracy and high convergence rate in the geometrically nonlinear analysis of composite shell structures

Estrogens in males: what have we learned in the last 10 years?

This review focuses on the role of estrogen in men, mainly in male reproduction. The continuing increase in data obtained, and recent discoveries in this area will enable a better understanding of male physiology; these, in turn, will have important clinical implications

Centrality of Striatal Cholinergic Transmission in Basal Ganglia Function

Work over the past two decades revealed a previously unexpected role for striatal cholinergic interneurons in the context of basal ganglia function. The recognition that these interneurons are essential in synaptic plasticity and motor learning represents a significant step ahead in deciphering how the striatum processes cortical inputs, and why pathological circumstances cause motor dysfunction. Loss of the reciprocal modulation between dopaminergic inputs and the intrinsic cholinergic innervation within the striatum appears to be the trigger for pathophysiological changes occurring in basal ganglia disorders. Accordingly, there is now compelling evidence showing profound changes in cholinergic markers in these disorders, in particular Parkinson's disease and dystonia. Based on converging experimental and clinical evidence, we provide an overview of the role of striatal cholinergic transmission in physiological and pathological conditions, in the context of the pathogenesis of movement disorders

An Isogeometric Solid-Shell Model for Postbuckling Optimisation Strategies

The optimal design of shell structures undergoing buckling phenomena is nowadays an open problem, whose solution would provide interesting answers to both academy and industry. The main difficulty is represented by the high computational cost required for optimising a full-scale structure characterised by a relatively complex postbuckling behaviour. In this work, this topic is addressed by proposing an isogeometric solid-shell model. The equilibrium path is evaluated through a multimodal Koiter's method. The resulting postbuckling analysis turns out to be efficient and accurate, as shown by numerical examples

Seismic vulnerability of masonry structures through a mechanical-based approach

Enhancing the territorial resilience to natural events, such as earthquakes, is assuming a primary role in the current political debate. In the context of Disaster Risk Management, developing reliable vulnerability models for the seismic risk assessment at a territorial scale is an aspect of crucial importance. In this perspective, the paper presents a mechanical-based method for the evaluation of local-scale seismic fragility curves for unreinforced masonry buildings, based on the exposure data collected in the Italian CARTIS database. It uses a bidimensional finite element model and static nonlinear analyses to obtain the structural behaviour. Monte Carlo simulations are performed to propagate the uncertainties. Both local and global scale structural behaviour are considered to define the damage grade. A case-study regarding the city centre of Cosenza, in southern Italy, validates the proposal

Prevalence of olfactory and other developmental anomalies in patients with central hypogonadotropic hypogonadism

Introduction: Hypogonadotropic hypogonadism (HH) is a heterogeneous disease caused by mutations in several genes. Based on the presence of hyposmia/anosmia it is distin- guished into Kallmann syndrome (KS) and isolated HH. The prevalence of other develop- mental anomalies is not well established. Methods: We studied 36 patients with HH (31 males, 5 females, mean age 41.5), 9 with familial and 27 with sporadic HH (33 congenital, 3 adult-onset), by physical examination, smell test (BSIT Sensonics), audiometry, renal ultrasound, and magnetic resonance imag- ing of the olfactory structures. Results: Based on the smell test, patients were classified as normosmic (n = 21, 58.3%) and hypo/anosmic (n = 15, 41.6%). Hypoplasia/agenesis of olfactory bulbs was found in 40% of patients (10/25; 75% hypo/anosmic, 7.6% normosmic, p<0.01, Fisher’s test). Remarkably, olfactory structures were normal in two anosmic patients, while one nor- mosmic patient presented a unilateral hypoplastic bulb. Fourteen of 33 patients (42.4%) presented neurosensorial hearing loss of various degrees (28.5% hypo/anosmic, 52.6% normosmic, p=NS). Renal ultrasound revealed 27.7% of cases with renal anomalies (26.6% hypo/anosmic, 28.5% normosmic, p = NS). At least one midline defect was found in 50% of the patients (53.3% hypo/anosmic, 47.6% normosmic, p = NS), including abnor- mal palate, dental anomalies, pectus excavatum, bimanual synkinesis, iris coloboma, and absent nasal cartilage. Anamnestically 4/31 patients reported cryptorchidism (25% hypo/anosmic, 5.2% normosmic, p = NS). Conclusion: Hypo/anosmia is significantly related to anatomical anomalies of the olfac- tory bulbs/tracts but the prevalence of other developmental anomalies, especially midline defects and neurosensorial hearing loss, is high both in HH and KS and independent of the presence of anosmia/hyposmia. From the clinical standpoint KS and normosmic HH should be considered as the same complex, developmental disease

Koiter asymptotic analysis of thin-walled cold-formed steel members

Abstract An imperfection sensitivity analysis of cold-formed steel members in compression is presented. The analysis is based on Koiter's approach and Monte Carlo simulation. If the modes interaction is correctly accounted, than the limit load and the erosion of critical buckling load can be easily evaluated. Thousands of imperfection can be analysed with very low computational cost and an effective statistical evaluation of limit performance can be carried out. The analysis is done on pallet rack uprights in compression, based on an intensive experimental study carried out at the Politehnica University of Timisoara

Robust and Efficient Large Deformation Analysis of Kirchhoff–love Shells: Locking, Patch Coupling and Iterative Solution

Isogeometric Kirchhoff-Love elements have received an increasing attention in geometrically nonlinear analysis of thin walled structures. They make it possible to meet the C1requirement in the interior of surface patches, to avoid the use of finite rotations and to reduce the number of unknowns compared to shear flexible models. Locking elimination, patch coupling and iterative solution are crucial points for a robust and efficient nonlinear analysis and represent the main focus of this work. Patch-wise reduced integrations are investigated to deal with locking in large deformation problems discretized via a standard displacement-based formulation. An optimal integration scheme for third order C2NURBS, in terms of accuracy and efficiency, is identified, allowing to avoid locking without resorting to a mixed formulation. The Newton method with mixed integration points (MIP) is used for the solution of the discrete nonlinear equations with a great reduction of the iterative burden and a superior robustness with respect to the standard Newton scheme. A simple penalty approach for coupling adjacent patches, applicable to either smooth or non-smooth interfaces, is proposed. An accurate coupling, also for a nonmatching discretization, is obtained using an interface-wise reduced integration while the MIP iterative scheme allows for a robust and efficient solution also with very high values of the penalty parameter

Outlining a Population “at Risk” of Parkinson’s Disease: Evidence from a Case-Control Study

The multifactorial pathogenesis of Parkinson’s Disease (PD) requires a careful identification of populations “at risk” of developing the disease. In this case-control study we analyzed a large Italian population, in an attempt to outline general criteria to define a population “at risk” of PD. We enrolled 300 PD patients and 300 controls, gender and age matched, from the same urban geographical area. All subjects were interviewed on demographics, family history of PD, occupational and environmental toxicants exposure, smoking status, and alcohol consumption. A sample of 65 patients and 65 controls also underwent serum dosing of iron, copper, mercury, and manganese by means of Inductively Coupled-Plasma-Mass-Spectrometry (ICP-MS). Positive family history, toxicants exposure, non-current-smoker, and alcohol nonconsumer status occurred as significant risk factors in our population. The number of concurring risk factors overlapping in the same subject impressively increased the overall risk. No significant differences were measured in the metal serum levels. Our findings indicate that combination of three to four concurrent PD-risk factors defines a condition “at risk” of PD. A simple stratification, based on these questionnaires, might be of help in identifying subjects suitable for neuroprotective strategies