Lowest order stabilization free Virtual Element Method for the Poisson equation

We introduce and analyse the first order Enlarged Enhancement Virtual Element Method (E^2VEM) for the Poisson problem. The method has the interesting property of allowing the definition of bilinear forms that do not require a stabilization term. We provide a proof of well-posedness and optimal order a priori error estimates. Numerical tests on convex and non-convex polygonal meshes confirm the theoretical convergence rates

SUPG-stabilized stabilization-free VEM: a numerical investigation

We numerically investigate the possibility of defining stabilization-free Virtual Element (VEM) discretizations of advection-diffusion problems in the advection-dominated regime. To this end, we consider a SUPG stabilized formulation of the scheme. Numerical tests comparing the proposed method with standard VEM show that the lack of an additional arbitrary stabilization term, typical of VEM schemes, that adds artificial diffusion to the discrete solution, allows to better approximate boundary layers, in particular in the case of a low order scheme.Comment: 15 page

Lowest order stabilization free Virtual Element Method for the Poisson equation

We introduce and analyse the first order Enlarged Enhancement Virtual Element Method (E$^2$VEM) for the Poisson problem. The method has the interesting property of allowing the definition of bilinear forms that do not require a stabilization term. We provide a proof of well-posedness and optimal order a priori error estimates. Numerical tests on convex and non-convex polygonal meshes confirm the theoretical convergence rates.Comment: 29 pages, 6 figure

Film inorganici per la protezione dell'acciaio inox

Deposizione di un coating di silice su substrati in acciaio inox attraverso una tecnica innovativa e caratterizzazione del film ottenutoope

Analysis of the relationships between wild ungulates and forest in the Northern Apennines, Italy

I explored some ecological aspects of the interaction between wild ungulates and forest environment. I reviewed the existent literature on the topic, and I found the relationship to be part of a extended ecological network, that includes several biotic and abiotic factors. The most advocated cause for elevated ungulate impact on forest is ungulate overabundance. Hence, I assessed the precision and applicability of three different census methods (drive census, pellet-group count, camera trapping method – REM) for roe deer in a mountainous forest. I found the R.E.M. method to be the best compromise, with intermediate precision and low demands. Moreover, I analyzed the browsing pressure of roe deer in several areas over a density gradient. I found the impact to be directly related to densities, and that the early-stage effects of browsing pressure will result in long-term differences in volume, between browsed and unbrowsed trees, even several years later the clear-cutting. Finally, to understand the effects of roe deer impact on the forest development, I used a forest development model (LANDIS-II) to simulate 200 years of forest development, considering harvesting and roe deer impact. I found that both disturbances influence species richness, abundance, and forest structure. Roe deer impact does not significantly affect harvesting yield, and the disturbances combined do not seem to represent an hazard for forest functionality

Model-aware Deep Learning Method for Raman Amplification in Few-Mode Fibers

One of the most promising solutions to overcome the capacity limit of current optical fiber links is space-division multiplexing, which allows the transmission on various cores of multi-core fibers or modes of few-mode fibers. In order to realize such systems, suitable optical fiber amplifiers must be designed. In single mode fibers, Raman amplification has shown significant advantages over doped fiber amplifiers due to its low-noise and spectral flexibility. For these reasons, its use in next-generation space-division multiplexing transmission systems is being studied extensively. In this work, we propose a deep learning method that uses automatic differentiation to embed a complete few-mode Raman amplification model in the training process of a neural network to identify the optimal pump wavelengths and power allocation scheme to design both flat and tilted gain profiles. Compared to other machine learning methods, the proposed technique allows to train the neural network on ideal gain profiles, removing the need to compute a dataset that accurately covers the space of Raman gains we are interested in. The ability to directly target a selected region of the space of possible gains allows the method to be easily generalized to any type of Raman gain profiles, while also being more robust when increasing the number of pumps, modes, and the amplification bandwidth. This approach is tested on a 70 km long 4-mode fiber transmitting over the C+L band with various numbers of Raman pumps in the counter-propagating scheme, targeting gain profiles with an average gain in the interval from 5 dB to 15 dB and total tilt in the interval from 1.425 dB to 1.425 dB. We achieve wavelengthand mode-dependent gain fluctuations lower than 0.04 dB and 0.02 dB per dB of gain, respectively

A lowest order stabilization-free mixed Virtual Element Method

We initiate the design and the analysis of stabilization-free Virtual Element Methods for the laplacian problem written in mixed form. A Virtual Element version of the lowest order Raviart-Thomas Finite Element is considered. To reduce the computational costs, a suitable projection on the gradients of harmonic polynomials is employed. A complete theoretical analysis of stability and convergence is developed in the case of quadrilateral meshes. Some numerical tests highlighting the actual behaviour of the scheme are also provided

Early and long-term impacts of browsing by roe deer in oak coppiced woods along a gradient of population density

Over the last few decades, wild ungulate populations have exhibited relevant geographic and demographic expansion in most European countries; roe deer is amongst the most widespread ungulate species. The increasing roe deer densities have led to strong impact on forest regeneration; the problem has been recently recognized in coppice woods, a silvicultural system which is widespread in Italy, where it amounts to about 56% of the total national forested area.In this study we investigated the effect of roe deer browsing on the vegetative regeneration of Turkey oak few years after coppicing, along a gradient of roe deer density. A browsing index revealed that browsing impact was high at any given roe deer density but increased at higher density, with the browsing rate ranging from 65% to 79%. We also analyzed the long-term impact of browsing six and eleven years after coppicing under a medium roe deer density. Results indicated the early impact are not ephemeral but produced prolonged impacts through time, with an average reduction in volume of -57% and -41% six and eleven years after coppicing, respectively. Based on these results we proposed integrating browsing monitoring with roe deer density estimation to allow identifying ungulate densities which are compatible with silvicultural and forest management objectives. The proposed browsing index can be regarded as an effective management tool, on account of its simplicity and cost-effectiveness, being therefore highly suitable for routine, large scale monitoring of browsing impact

Fatores associados ao nível de dor na admissão e na alta em vítimas de trauma

Introduction: Different factors may be associated with the genesis and maintenance of pain symptoms in trauma. the underevaluation and undertreatment of acute pain in emergency units have called in an unqualified care, increasing morbidity and length of hospital stay. the objective of this investigation was to determine the factors associated with the level of pain on admission and at discharge in trauma. Methodology: Cross-sectional study with 92 trauma victims treated at an emergency unit in southern Brazil. the intensity and location of pain were assessed, respectively, through the numerical pain scale and body diagram. data were analyzed with the aid of non-parametric statistics. Results: The results showed that were associated with more severe pain on admission or discharge characteristics like being male, younger age, non-white skin color, companion presence, burn-like lesions, presence of drug prescription, analgesic administration intravenously and longer than 30 minutes for pain relief with pharmacotherapy. Conclusion: The imposition of protocols or algorithms of measurement and treatment of pain by health professionals in emergency units should consider these characteristics in order to provide a resolutive and quality care  Introducción: Diferentes factores pueden estar asociados a la génesis y mantenimiento del cuadro de dolor en víctimas de trauma. La baja evaluación y el bajo tratamiento del dolor agudo en las unidades de urgencia han llevado a una atención descalificada, aumentando la morbilidad y el tiempo de internación. El objetivo de esta investigación fue verificar los factores asociados al nivel de dolor en la admisión y en el alta en víctimas de trauma. Metodología: Estudio transversal, realizado con 92 víctimas de trauma atendidas en una unidad de urgencia en el Sur de Brasil. La intensidad y ubicación del dolor fueron evaluadas, respectivamente, por medio de la escala numérica de dolor y diagrama corporal. Los datos fueron analizados con ayuda de la estadística no paramétrica. Resultados: Los hallazgos indicaron asociación del dolor más intenso en la admisión o en el alta a características como: sexo masculino, edad más joven, color de la piel no blanca, presencia de compañero, heridas ocasionadas por quemadura, presencia de prescripción medicamentosa, administración analgésica por vía endovenosa y tiempo superior a 30 minutos para mejora del dolor con la farmacoterapia. Conclusión: La institución de protocolos o algoritmos de medición y tratamiento del dolor por los profesionales de salud en las unidades de urgencia debe considerar tales características a fin de prestar una asistencia resolutiva y de calidad.Introdução: Diferentes fatores podem estar associados à gênese e manutenção do quadro álgico em vítimas de trauma. A subavaliação e o subtratamento da dor aguda nas unidades emergenciais têm acarretado em um atendimento desqualificado, aumentando a morbidade e o tempo de internação. O objetivo desta investigação foi verificar os fatores associados ao nível de dor na admissão e na alta em vítimas de trauma. Metodologia: Estudo transversal, realizado com 92 vítimas de trauma atendidas em uma unidade emergencial no Sul do Brasil. A intensidade e localização da dor foram avaliadas, respectivamente, por meio da escala numérica de dor e diagrama corporal. Os dados foram analisados com o auxílio de estatística não paramétrica. Resultados: Os achados demonstraram que estiveram associadas à dor mais intensa na admissão ou na alta características como: sexo masculino, idade mais jovem, cor da pele não branca, presença de companheiro, lesões do tipo queimadura, presença de prescrição medicamentosa, administração analgésica por via endovenosa e tempo superior a 30 minutos para melhora da dor com a farmacoterapia. Conclusão: A instituição de protocolos ou algoritmos de mensuração e tratamento da dor pelos profissionais de saúde nas unidades emergenciais deve considerar tais características a fim de se prestar uma assistência resolutiva e de qualidade