An alternative approach to field-aligned coordinates for plasma turbulence simulations

Turbulence simulation codes can exploit the flute-like nature of plasma turbulence to reduce the effective number of degrees of freedom necessary to represent fluctuations. This can be achieved by employing magnetic coordinates of which one is aligned along the magnetic field. This work presents an approach in which the position along the field lines is identified by the toroidal angle, rather than the most commonly used poloidal angle. It will be shown that this approach has several advantages. Among these, periodicity in both angles is retained. This property allows moving to an equivalent representation in Fourier space with a reduced number of toroidal components. It will be shown how this duality can be exploited to transform conventional codes that use a spectral representation on the magnetic surface into codes with a field-aligned coordinate. It is also shown that the new approach can be generalised to get rid of magnetic coordinates in the poloidal plane altogether, for a large class of models. Tests are carried out by comparing the new approach with the conventional approach employing a uniform grid, for a basic ion temperature gradient (ITG) turbulence model implemented by the two corresponding versions of the ETAI3D code. These tests uncover an unexpected property of the model, that localized large parallel gradients can intermittently appear in the turbulent regime. This leaves open the question whether this is a general property of plasma turbulence, which may lead one to reconsider some of the usual assumptions on micro-turbulence dynamics.Comment: 19 pages (once in pdf format). 1 LaTeX file and 10 eps figures in the zip folde

Adjuvant radiochemotherapy for gastric cancer. Should we use prognostic factors to select patients?

Radiotherapy has a not well-established role in the pre-operative and in the post-operative setting in gastric cancer (GC) patients. Randomized trials report controversial outcomes and impact on survival. In the D2 loco-regional node resection era, after a well-performed radical surgery, local treatment using radiotherapy combined to chemotherapy should be considered for locally advanced GC. Prognostic factors could help the better selection of subgroups that present high risk of loco-regional recurrence. Then, the addition of radiotherapy could improve the disease-free survival and also quality of life. There are no large prospective studies that have assessed specific factors predicting for recurrence or survival, but only retrospective series, some of them including high number of patients with homogeneous characteristics. In locally advanced GC adding radiotherapy to the post-operative chemotherapy seems to improve outcomes and quality of life. Prognostic factors such as T-stage, N-status, nodal ratio, and other histological factors should be considered to submit patients to post-operative combined treatment. Larger prospective series are necessary to investigate the role of combined chemoradiation after radical D2-resection, especially in locally advanced GC. Further prospective investigations are needed to suggest prognostic factors that have significant impact on survival and recurrence, improving the management and outcomes, particularly in locally advanced GC patients

Sintesi di nuovi sistemi triciclici aromatici lineari. Triazolochinoloni, imidazochinoloni e 4-osso-piridochinossaline quali potenziali agenti DNA intercalanti

Recentemente abbiamo riportato la sintesi di alcuni nuovi sistemi triciclici lineari aromatici azotati che per la loro tipicità, una volta opportunamente funzionalizzati, potranno essere saggiati al fine di valutarne la potenzialità farmacologia

The role of stereotactic body radiation therapy in oligometastatic colorectal cancer

Rationale: Regorafenib is the new standard third-line therapy in metastatic colorectal cancer (mCRC). However, the reported 1-year overall survival rate does not exceed 25%. Patient concerns: A 55-year-old man affected by mCRC, treated with regorafenib combined with stereotactic body radiotherapy (SBRT), showing a durable response. Interventions: After 6 months of regorafenib, a PET/CT scan revealed a focal uptake in a solid lung nodule which was treated with SBRT, whereas continuing regorafenib administration. Fourteen months later, the patient had further progression in a parasternal lymph node, but treatment with regorafenib was continued. The regorafenib-associated side effects, such us the hand-foot syndrome, were favorable managed by reducing the dose from 160 to 120 mg/day. Outcomes: Patient-reported outcome was characterized by a progression-free survival of approximately 3 years. Lessons: in presence of oligometastatic progression, a local SBRT while retaining the same systemic therapy may be a better multidisciplinary approach. Moreover, disease progression is no longer an absolute contraindication for continuing the regorafenib treatment

Modeling of the Rheological Properties of Asphalt Binder and Asphalt Mortar Containing Recycled Asphalt Material

Abstract The use of recycled materials in asphalt pavements increased significantly over the years, determining well known environmental and economic benefits. Many research agencies and road authorities evaluated the impact of Recycled Asphalt Pavement (RAP) on pavement performance. Nevertheless, the mechanism governing the interaction between virgin asphalt binder and aged RAP binder is not well understood. In this paper, the effect of RAP on the rheological properties of asphalt binders and mortars is experimentally evaluated, and theoretically modeled with the objective of defining a relationship between the linear viscoelastic (LVE) properties of binders and those of the corresponding mortars. Three asphalt binder types, obtained by blending a hard and a soft binder at three different percentages, were mixed with three different contents of a Selected fraction of Recycled Asphalt Pavement, called SRAP, for preparing the asphalt mortar samples. Dynamic Shear Rheomether tests were performed on binders and mortars to determining the complex modulus over a wide range of temperatures and frequencies. The rheological properties of the compound of virgin and RAP binder were evaluated by using a new approach based on a modified version of the Nielsen model, avoiding the extraction and recovery method. The results were then modelled by using the analogical 2S2P1D model, consisting of one spring, two parabolic and one-dashpot elements combined in series and then assembled together with a second spring in parallel. Based on test results, a simple experimental relationship between the characteristic times of the binder and the percentage of RAP in the mortar was found

Investigation of Low Temperature Properties of Asphalt Mixture Containing Recycled Asphalt Materials

L’uso di sempre maggiori quantita’ di Reclaimed Asphalt Pavement (RAP) nella costruzione di pavimentazioni stradali in conglomerato bituminoso e’ diventata una delle maggiori priorita’ per i suoi benefici economici e ambientali. Di recente, altri materiali quali Recycled Asphalt Shingles (RAS) hanno trovato stesso campo di applicazione. Tuttavia pochi sono gli studi eseguiti sull’impiego di RAP e RAS alle basse temperature. Questa tesi si occupa di studiare l’uso di tre materiali di riciclo, RAP, Tear off Scrap Shingles (TOSS) and Manufacturer Waste Scrap Shingles (MWSS) nelle miscele di conglomerato bituminoso alle basse temperature, tramite prove sperimentali, analisi statistica e modellazione. La parte sperimentale prevede prove di three-point bending creep con il Bending Beam Rheometer (BBR) su 17 miscele di conglomerato bituminoso. L’effetto di RAP, TOSS e MWSS su creep stiffness, m-value, thermal stress e critical temperature e’ stato valutato tramite analisi statistica, evidenziando come TOSS e MWSS influenzino le prestazioni del conglomerato bituminoso solo per specifici contenuti di RAP. Nella parte teorica, i provini di conglomerato bituminoso sono stati analizzati sulla base di digital image analysis, modelli micromeccanici e analogici e con simulazioni agli elementi finiti. La frazione volumica e la distribuzione granulometrica sono state stimate a aprtire dalle binary images attraverso digital processing. La frazione volumica e la distribuzione granulometrica media degli aggregati dei 17 conglomerati bituminosi analizzati sono risultate molto simili nonsotante siano stati impiegati differenti quantita’ di materiale riciclato per il loro confezionamento. La struttura interna delle miscele di conglomerato bituminoso e’ stata analizzata tramite la valutazione della spatial correlation functions dei provini di BBR. L’assenza di ampie fluttuazioni delle correlation functions ha indicato che la microstruttura delle differenti miscele non e’ influenzata dalla presenza di RAP, TOSS e MWSS. Due modelli, uno micromeccanico e uno analogico, sono stati usati per la backcalculation della creep stiffness del legante bituminoso per un numero ridotto di miscele e i risultati successivamente confrontati con la creep stiffness ottenuta sperimentalmente dal legante estratto. Questo ha permesso di notare come i riusltati della backcalculation diano valori di creep stiffness molto piu’ elevati rispetto a quelli del legante estratto. Infine i due modelli, micromeccanico e analogico, sono stati validati tramite simulazioni bidimensionali agli elementi finiti.The use of increased proportions of Reclaimed Asphalt Pavement (RAP) in the construction of asphalt pavements has become a top priority due to its economical and environmental benefits. Moreover other materials as Recycled Asphalt Shingles (RAS) have recently found their applicability in the same field. However in spite of a significant number of studies on the use of RAP and RAS, little was done to investigate the behavior at low temperature of pavement containing these two types of materials. In this thesis the effect of using three recycled materials RAP, Tear off Scrap Shingles (TOSS) and Manufacturer Waste Scrap Shingles (MWSS), on the asphalt mixture behavior at low temperature is investigated based on statistical analysis and modeling of an extensive set of experiments. The experimental part consisted of three-point bending creep tests performed on BBR (Bending Beam Rheometer) beams (6.25 × 12.5 × 100 mm) obtained from 17 different asphalt mixtures. Statistical analysis of the effect of RAP, TOSS and MWSS on creep stiffness, m-value, thermal stress and critical temperature was performed showing that TOSS and MWSS affect asphalt mixture performance only for specific amount of RAP. In the theoretical part, asphalt mixtures specimens were analyzed based on digital image analysis, micromechanical and analogical models and finite element simulations. The volumetric fractions and particle size distributions of the different asphalt mixtures were estimated from their binary images after digital processing. The volumetric fraction and the average size distribution of aggregates for the 17 asphalt mixtures investigated were found to be very similar despite of the varying amount of recycled material contained. Detailed information on the internal structure of asphalt mixture was investigated by estimating the spatial correlation functions of the beam specimens. No large fluctuation of the functions were detected meaning that the microstructure of the asphalt mixtures was not affected by the presence of RAP, TOSS and MWSS. Micromechanical and analogical models were used to backcalculate the creep stiffness of the binder for a limited number of mixtures and the prediction was compared to the creep stiffness obtained from the corresponding extracted binders. A noticeable difference was detected with the prediction having much higher values. Finally, two-dimensional finite element simulations of three point bending were used to validate the micromechanical an analogical model used

Uma Comparação Entre o Método dos Elementos de Contorno e o Método das Soluções Fundamentais em Problemas de Laplace.

Neste trabalho comparam-se os desempenhos numéricos dos Métodos dos Elementos de Contorno (MEC) e Método das Soluções Fundamentais Clássico (MSF) na solução de problemas governados pela Equação de Laplace. São métodos similares, que usam a idéia de uma solução fundamental, mas também apresentam algumas distinções importantes. É possível fazer com que estas diferentes técnicas interajam na solução de alguns problemas mais complexos, o que implica em maior conhecimento das particularidades do MSF, uma vez que o MEC é atualmente uma técnica muito mais conhecida, de reconhecida eficiência em diversas aplicações importantes. Já o MSF experimenta uma redescoberta a partir da intensificação das técnicas de discretização sem malha. Este trabalho compara a precisão dos dois métodos e examina algumas particularidades numéricas de ambos em exemplos simples, mas importantes para a identificação do alcance de cada técnica. Palavras chave: Método dos Elementos de Contorno, Método das Soluções Fundamentais, Problemas de Laplace, Comparação entre Métodos

How technology can help in oncologic patient management during COVID-19 outbreak

No abstract availabl

Vaitehii: the cradle of the basalt adze-blades on Nuku Hiva, Marquesas Islands

Vaitehii, Terre Déserte, is a well-known district by the hunters of Nuku Hiva, as an adze-production site. In 1998 Judit Antoni and Alfred Falchetto visited the region: we wanted to collect objects for future studies. Taking the opportunity, we try to show a little overview on these objects (debris of production, flakes and half-products)