1,721,177 research outputs found
Polymorphic light eruption: What's new in pathogenesis and management
No full textPolymorphic light eruption is the commonest photosensitive disorder, characterized by an intermittent eruption of non-scarring erythematous papules, vesicles or plaques that develop within hours of ultraviolet radiation exposure of patient skin. Together with the lesions, a terrible itch starts and increases with the spreading of the disease, sometimes aggravated by a sort of burning sensation. Clinical picture and symptoms can improve during the rest of the summer with further solar exposures. In the last years many advances have been performed in the knowledge of its pathogenesis and some news have been proposed as preventive, as well as therapeutic options. All this has been discussed in the current mini review
Fatigue analysis of a post-buckled composite single-stringer specimen taking into account the local stress ratio
Full text linkThe fatigue life prediction of post-buckled composite structures represents still an unresolved issue due to the complexity of the phenomenon and the high costs of experimental testing. In this paper, a novel numerical approach, called “Min-Max Load Approach”, is used to analyze the behavior of a composite single-stringer specimen with an initial skin-stringer delamination subjected to post-buckling fatigue compressive load. The proposed approach, based on cohesive zone model technique, is able to evaluate the local stress ratio during the delamination growth, performing, in a single Finite Element analysis, the simulation of the structure at the maximum and minimum load of the fatigue cycle. The knowledge of the actual value of the local stress ratio is crucial to correctly calculate the crack growth rate. At first, the specimen is analyzed under quasi-static loading conditions, then the fatigue simulation is performed. The results of the numerical analysis are compared with the data of an experimental campaign previously conducted, showing the capabilities of the proposed approach
Analysis of local stress ratio for delamination in composites under fatigue loads
Full text linkAn approach based on the cohesive zone model for analyzing delamination in composite laminates under cyclic fatigue loading is presented. The proposed technique, called “min-max load approach,” is able to dynamically capture the local stress ratio during the progression of delamination. The possibility to know the local stress ratio is relevant in all the situations where its value is different from the applied load ratio and cannot be determined a priori. The methodology analyzes in a single finite element analysis two identical models with two different constant loads, the minimum and the maximum load of the fatigue cycle. The two models interact with each other, exchanging information to calculate the crack growth rate. At first, the approach has been validated in simulations of mode I and mixed-mode propagation using double cantilever beam and mixed-mode bending tests. Then, to prove the effectiveness of the developed methodology, a modified version of the mixed-mode bending test has been analyzed. Mode I and mode II components of the load are decoupled and applied independently, resulting in a local stress ratio different from the applied load ratio. The results obtained from the simulations, compared with the analytical model obtained using the corrected beam theory, show that the proposed approach is able to predict the local stress ratio and thereby to correctly evaluate the crack growth rate during the propagation of the damage
L'aborto dopo la legge 194/78: rischio tutelato o escluso nell'assicurazione privata contro le malattie?
No full textA numerical approach for the evaluation of the local stress ratio in fatigue-driven delamination analysis
No full textAn approach based on the cohesive zone model for analyzing fatigue-driven delamination in composite structures under cyclic loading is presented. The proposed technique, called “Min-Max Load Approach”, is able to dynamically capture the local stress ratio during the evolution of damage. The possibility to know the local stress ratio is relevant in all the situations where its value is different from the applied load ratio and cannot be determined a priori. In a single Finite Element analysis, two identical models are analyzed with two different constant loads, the minimum and the maximum load during the fatigue cycle. The implemented methodology allows the two models to interact with each other, by exchanging information to correctly calculate the crack growth rate. At first, the approach has been validated in simulations of mode I and mixed-mode propagation by using Double Cantilever Beam and Mixed-Mode Bending. Then, to prove the effectiveness of the developed methodology, a modified version of the Mixed-Mode Bending test has been numerically investigated. In this test, the mode I and mode II components of the load are decoupled and applied independently, resulting in a local stress ratio different from the applied load ratio
Atopic dermatitis: Epidemiology and clinical phenotypes
No full textAtopic dermatitis (AD) is a chronic, lifelong, relapsing condition. The wide spectrum of the possible clinical presentations, depending on patient' s age, age of onset of disease, topography and morphology of dermatitis, limits the epidemiologic information on its prevalence and incidence. A clear definition of the different clinical AD phenotypes and epidemiology is essential for an appropriate patient's treatment and management, in particular for adults. This review summarizes the most recent epidemiologic data from the 21st century, on AD prevalence and incidence rates either in children or adults, with a special focus on their trends in Europe. Moreover, an effort to categorize diverse AD clinical expressions, has been made, aiming to facilitate differential diagnosis and speed up the start of the correct therapy
A robust numerical approach for the simulation of skin–stringer debonding growth in stiffened composite panels under compression
No full textIn this paper, a numerical study on skin–stringer debonding growth in stiffened composite panels has
been carried out. A novel numerical methodology is proposed here to investigate the compressive behaviour
of a stiffened composite panel in the presence of skin–stringer partial separation. The novel numerical
methodology, able to overcome the mesh size and time increment dependency of the standard
Virtual Crack Closure Technique (VCCT), is an evolution of a previously developed and tested numerical
approach for the circular delaminations growth. The enhancements, with respect to the previously developed
approach, rely mainly in the capability to deal with the different defect shapes characterising a
skin–stringer debonding. The proposed novel methodology has been implemented in a commercial finite
element platform and tested over single stiffener composite panels. The effectiveness of the suggested
numerical methodology, in predicting the compressive behaviour of stiffened panels with skin stringer
debondings, has been preliminary confirmed by comparisons, in terms of load versus applied displacement
and debonding size at failure, with literature experimental data and numerical results obtained
with the standard VCCT approach
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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