Cost-effective and accurate interlaminar stress modeling of composite Kirchhoff plates via immersed isogeometric analysis and equilibrium

The interest for composites has constantly grown in recent years, especially in the aerospace and automotive industries, as they can be moulded in complex form and geometry, as well as exhibit enhanced engineering properties. Nevertheless, despite the accelerated diffusion of laminated composites, the design of these materials is often restrained by the lack of cost-effective modeling techniques. In fact, the existing numerical strategies allowing for cheap simulations of laminated structures usually fail to directly capture out-of-plane through-the-thickness stresses, which are typically responsible for failure modes such as delamination. In this context, a stress recovery approach based on equilibrium has been recently shown to be an efficient modeling strategy in the framework of isogeometric analysis. Since immersed approaches like the finite cell method have been proven to be a viable alternative to mesh-conforming discretization for dealing with complex/dirty geometries as well as trimmed surfaces, we herein propose to extend the stress recovery approach combining the finite cell method, isogeometric analysis and equilibrium to model the out-of-plane behavior of Kirchhoff laminated plates. Extensive numerical tests showcase the effectiveness of the proposed approach

Solution of the stationary stokes and navier-stokes equations using the modified finite particle method in the framework of a least squares residual method

The present work is concerned with the solution of stationary Stokes and Navier-Stokes flows using the Modified Finite Particle Method for spatial derivative approximations and the Least Square Residual Method for the solution of the linear system deriving from the collocation procedure. The combination of such approaches permits to easily handle the numerical difficulty of the inf-sup conditions, without distinguishing between the discretizations of velocity and pressure fields. The obtained results, both in the cases of linear and non-linear flows, show the robustness of the proposed algorith

A focal plane detector design for a wide-band Laue-lens telescope

The energy range above 60 keV is important for the study of many open problems in high energy astrophysics such as the role of Inverse Compton with respect to synchrotron or thermal processes in GRBs, non thermal mechanisms in SNR, the study of the high energy cut-offs in AGN spectra, and the detection of nuclear and annihilation lines. Recently the development of high energy Laue lenses with broad energy bandpasses from 60 to 600 keV have been proposed for a Hard X ray focusing Telescope (HAXTEL) in order to study the X-ray continuum of celestial sources. The required focal plane detector should have high detection efficiency over the entire operative range, a spatial resolution of about 1 mm, an energy resolution of a few keV at 500 keV and a sensitivity to linear polarization. We describe a possible configuration of the focal plane detector based on several CdTe/CZT pixelated layers stacked together to achieve the required detection efficiency at high energy. Each layer can operate both as a separate position sensitive detector and polarimeter or work with other layers to increase the overall photopeak efficiency. Each layer has a hexagonal shape in order to minimize the detector surface required to cover the lens field of view. The pixels would have the same geometry so as to provide the best coupling with the lens point spread function and to increase the symmetry for polarimetric studies.Comment: 10 pages, 9 figure

Lamotrigine versus valproic acid as first-line monotherapy in newly diagnosed typical absence seizures: an open-label,randomized, parallel-group study

Purpose: To compare the efficacy of lamotrigine (LTG) and valproic acid (VPA) in newly diagnosed children and adolescents with typical absence seizures. Methods: A randomized, open-label parallel-group design was used. After undergoing an awake video-EEG recording, which included one to two trials of 3 min of hyperventilation and intermittent photic stimulation, eligible patients were randomized to receive LTG or VPA. LTG was initiated at a daily dose of 0.5 mg/kg for 2 weeks in two divided doses, followed by 1.0 mg/kg/day for an additional 2 weeks. Thereafter, doses were increased in 1-mg/kg/day increments every 5 days until seizures were controlled, intolerable adverse effects occurred, or a maximum dose of 12 mg/kg/day had been reached. VPA was equally uptitrated according to clinical response, starting at 10 mg/kg and increasing by 5 mg/kg/24 h every 3 days, if required, to a maximum of 30 mg/kg/day in three divided doses. Patients were seen in the clinic every month for ≤12 months.The primary efficacy end point at each visit was seizure freedom, defined as lack of clinically observed seizures since the previous visit and lack of electroclinical seizures during ambulatory 24-h EEG testing and a video-EEG session with hyperventilation. Results: Thirty-eight children (17 boys, 21 girls), aged from 3 to 13 years (mean, 7.5 years), all newly diagnosed with childhood or juvenile typical absence seizures, were enrolled. After 1 month of treatment, 10 (52.6%) of 19 children taking VPA and one (5.3%) of 19 taking LTG were seizure free (p = 0.004). By the 3-month follow-up, 12 (63.1%) children taking VPA and seven (36.8%) taking LTG were controlled (p = 0.19). After 12 months, 13 children taking VPA (dose range, 20–30 mg/kg/day; mean serum level, 76.8 mg/L; range, 51.4–91 mg/L) and 10 taking LTG (dose range, 2–11 mg/kg/day; mean serum level, 8.1 mg/L; range, 1.1–18 mg/L) were seizure free (p=0.51). Side effects were mostly mild and transient and were recorded in two (10.6%) children treated with VPA and in six (31.8%) treated with LTG. Conclusions: Both VPA and LTG can be efficacious against absence seizures, although VPA shows a much faster onset of action, at least in part because of its shorter titration schedule. KeyWords: Lamotrigine—Valproic acid—Typical absences— Monotherapy. Valproic acid (VPA) and ethosuximide (ESM) have been shown to be equally effective as monotherapy for typical absence seizures (1,2), and, at present, they are generally considered first-choice drugs for this seizure type. VPA controls absences in∼75% of patients, in addition to being effective against generalized tonic–clonic seizures (70%) and myoclonic seizures (75%). However, its use may involve safety risks for postmenarchal women (3). ESM produces complete control of absences in 70% of treated patients (4,5), but it is unsuitable as monotherapy Accepted Ma

A Stability Study of some Mixed Finite Elements for Large Deformation Elasticity Problems

We consider the finite elasticity problem for incompressible materials, proposing a simple bidimensional problem for which we provide an indication on the solution stability. Furthermore, we study the stability of discrete solutions, obtained by means of some well-known mixed finite elements, and we present several numerical experiments

Haemodynamic Benefit of Cardiac Resynchronisation Therapy Requires Left Bundle Branch Block: A Case Report

A 55-year-old woman with dilated cardiomyopathy and rate-dependent left bundle branch block had a cardiac resynchronisation therapy (CRT) device implanted. During implantation, the maximum rate of left ventricular pressure rise (dP/dtmax) was measured invasively. This case presents a description of the acute negative effect of a left bundle branch block on dP/dtmax, and the different effect of CRT on left ventricular haemodynamic function in the presence and absence of a left bundle branch block

Topiramate in children and adolescents with epilepsy and mental retardation: a prospective study on behavior and cognitive effects.

The aim of the present study was to assess the behavioral and cognitive effects following treatment with topiramate in children and adolescents with epilepsy with mild to profound mental retardation. The study group comprised 29 children, 16 males and 13 females, aged 3 to 19 years, affected by partial (4) and generalized (25) crypto/symptomatic epilepsy and mental retardation (7 mild, 5 moderate, 15 severe, 2 profound), who were administered topiramate (TPM) as add-on therapy to their baseline antiepileptic treatment. At baseline, 3 months, 6 months, and 12 months, parents or caregivers of each patient were administered a questionnaire based on the Holmfrid Quality of Life Inventory. After a 3-month follow-up, the add-on topiramate caused overall mild to moderate cognitive/behavioral worsening in about 70% of children and adolescents with mental retardation and epilepsy. After 6 and 12 months of follow-up, global worsening persisted in 31 and 20.1% of cases, respectively. In conclusion, this trial confirms that TPM can have significant adverse cognitive and behavioral side effects, even in mentally disabled children and adolescents. 2007 Elsevier Inc. All rights reserved

A novel layered topology of auxetic materials based on the tetrachiral honeycomb microstructure

Microstructured honeycomb materials may exhibit exotic, extreme and tailorable mechanical properties, suited for innovative technological applications in a variety of modern engineering fields. The paper is focused on analysing the directional auxeticity of tetrachiral materials, through analytical, numerical and experimental methods. Theoretical predictions about the global elastic properties have been successfully validated by performing tensile laboratory tests on tetrachiral samples, realized with high precision 3D printing technologies. Inspired by the kinematic behaviour of the tetrachiral material, a newly-design bi-layered topology, referred to as bi-tetrachiral material, has been theoretically conceived and mechanically modelled. The novel topology virtuously exploits the mutual collaboration between two tetrachiral layers with opposite chiralities. The bi-tetrachiral material has been verified to outperform the tetrachiral material in terms of global Young modulus and, as major achievement, to exhibit a remarkable auxetic behaviour. Specifically, experimental results, confirmed by parametric analytical and computational analyses, have highlighted the effective possibility to attain strongly negative Poisson ratios, identified as a peculiar global elastic property of the novel bi-layered topology