Time--Splitting Schemes and Measure Source Terms for a Quasilinear Relaxing System

Several singular limits are investigated in the context of a $2 \times 2$ system arising for instance in the modeling of chromatographic processes. In particular, we focus on the case where the relaxation term and a $L^2$ projection operator are concentrated on a discrete lattice by means of Dirac measures. This formulation allows to study more easily some time-splitting numerical schemes

Inestabilidad de tanques de petróleo durante su construcción : Estudio de caso

Este trabajo analiza, en forma numérica y experimental, la estabilidad de un tanque cilíndrico de acero de pared delgada sin techo (en etapa de construcción) no anclado, frente a cargas de viento. El tanque estudiado se encuentra en la zona Norte de la Patagonia y colapsó por viento a una velocidad de 50Km/h. Las normas que permiten diseñar los tanques de almacenamiento se concentran en su comportamiento finalizada la construcción, descuidando la etapa constructiva. El presente estudio se desarrolla en dos etapas. En una primera etapa se realiza un análisis fluido-dinámico midiendo presiones sobre modelos de tanques en túnel de viento. En la segunda etapa se analiza la respuesta estructural evaluando numéricamente las cargas que producen pandeo. Para el estudio numérico se simula la estructura por elementos finitos con un código de propósitos múltiples(ABAQUS), mediante análisis de bifurcación lineal y análisis no lineal geométrico con imperfecciones. Los resultados experimentales muestran que las presiones a barlovento en las paredes del tanque se incrementan un 40% debido a las presiones internas y, además, las presiones actuando en la base tienden a levantarla. Los resultados numéricos permiten vincular la carga de colapso en el tanque con las velocidades registradas en el lugar.Publicado en: Mecánica Computacional vol. XXXV no.38Facultad de Ingenierí

A nonlinear model for marble sulphation including surface rugosity: Theoretical and numerical results

We consider an evolution system describing the phenomenon of marble sulphation of a monument, accounting of the surface rugosity. We first prove a local in time well posedness result. Then, stronger assumptions on the data allow us to establish the existence of a global in time solution. Finally, we perform some numerical simulations that illustrate the main feature of the proposed model

miRNA-guided reprogramming of glucose and glutamine metabolism and its impact on cell adhesion/migration during solid tumor progression

MicroRNAs (miRNAs) are small, non-coding RNAs about 22 nucleotides in length that regulate the expression of target genes post-transcriptionally, and are highly involved in cancer progression. They are able to impact a variety of cell processes such as proliferation, apoptosis and differentiation and can consequently control tumor initiation, tumor progression and metastasis formation. miRNAs can regulate, at the same time, metabolic gene expression which, in turn, influences relevant traits of malignancy such as cell adhesion, migration and invasion. Since the interaction between metabolism and adhesion or cell movement has not, to date, been well understood, in this review, we will specifically focus on miRNA alterations that can interfere with some metabolic processes leading to the modulation of cancer cell movement. In addition, we will analyze the signaling pathways connecting metabolism and adhesion/migration, alterations that often affect cancer cell dissemination and metastasis formation

Surgical site infection after caesarean section. Space for post-discharge surveillance improvements and reliable comparisons

Surgical site infections (SSI) after caesarean section (CS) represent a substantial health system concern. Surveying SSI has been associated with a reduction in SSI incidence. We report the findings of three (2008, 2011 and 2013) regional active SSI surveillances after CS in community hospital of the Latium region determining the incidence of SSI. Each CS was surveyed for SSI occurrence by trained staff up to 30 post-operative days, and association of SSI with relevant characteristics was assessed using binomial logistic regression. A total of 3,685 CS were included in the study. A complete 30 day post-operation follow-up was achieved in over 94% of procedures. Overall 145 SSI were observed (3.9% cumulative incidence) of which 131 (90.3%) were superficial and 14 (9.7%) complex (deep or organ/space) SSI; overall 129 SSI (of which 89.9% superficial) were diagnosed post-discharge. Only higher NNIS score was significantly associated with SSI occurrence in the regression analysis. Our work provides the first regional data on CS-associated SSI incidence, highlighting the need for a post-discharge surveillance which should assure 30 days post-operation to not miss data on complex SSI, as well as being less labour intensive

VENTILAÇÃO CONTROLADA COM PRESSÃO EXPIRATÓRIA FINAL POSITIVA EM SUÍNOS ANESTESIADOS COM ISOFLURANO OU HALOTANO E SUBMETIDOS A PNEUMOPERITÔNIO OU PNEUMOTÓRAX COM CO2

A homeostase hemodinâmica e respiratória nas vídeo cirurgias onde se emprega insuflação abdominal ou torácica requer métodos especiais de ventilação como a pressão expiratória final positiva (PEEP). Este experimento teve por objetivo avaliar a hemodinâmica e a oxigenação de suínos submetidos anestesia geral com isoflurano ou halotano onde foi realizado pneumoperitôneo a uma pressão constante de 15 mmHg ou pneumotórax de 5 mmHg com CO2 e ventilados com pressão expiratória zero ou 10 cm de H2O. Foram estudadas as variáveis pressão arterial (sistólica, média e diastólica), freqüência cardíaca e respiratória, saturação de oxigênio na hemoglobina (SpO2), volume corrente e minuto, eletrocardiografia e ainda pressão parcial de dióxido de carbono expirado. Onde foram observados valores de SpO2 mais elevados nos grupos submetidos a PEEP e maior hipotensão nos suínos anestesiados com halotano, nos permitindo concluir que quando comparado com o grupo que recebeu pressão expiratória final zero o uso de 10 cm de água de PEEP melhora a SpO2 e o isoflurano é superior ao halotano na manutenção da função cardiovascular de suínos submetidos à insuflação intra-abdominal ou intratorácica com CO2. Controlled ventilation with Positive End-Expiratory Pressure in isoflurane or halotane anesthetized pigs submitted to pneumoperitoneum or pneumothorax with CO2 Abstract Hemodynamic and respiratory homeostasy in the video surgeries need special ventilatory methods as positive end-expiratory pressure (PEEP). This study aimed to investigate the hemodynamic and oxygenation effects in isoflurane or halotane anesthetized pigs, submitted to constant 15 mm Hg CO2 abdominal pressure or 5 mm Hg CO2 intrathoracic pressure of 10 cm of H2O of PEEP or 0 cm of H2O (ZEEP). Variables studied were arterial pressure (systolic, diastolic and mean) heart rate, respiratory rate, SpO2, tidal volume, minute volume, electrocardiogram and expiratory end-tidal carbon dioxide. Were observed improved in SpO2 with 10 cm of H2O PEEP and more hypotension in the halotane anesthetized group. We conclude that when compared to ZEEP group, 10 cm of H2O PEEP ventilation improves SPO2, while isoflurane is better to maintain the cardiovascular function to anesthetized pigs submitted to 15 mm Hg intra-abdominal and 5 mm Hg intratoracic pressure insufflations with CO2

Design of a modular Autonomous Underwater Vehicle for archaeological investigations

MARTA (MARine Tool for Archaeology) is a modular AUV (Autonomous Underwater Vehicle) designed and developed by the University of Florence in the framework of the ARROWS (ARchaeological RObot systems for the World's Seas) FP7 European project. The ARROWS project challenge is to provide the underwater archaeologists with technological tools for cost affordable campaigns: i.e. ARROWS adapts and develops low cost AUV technologies to significantly reduce the cost of archaeological operations, covering the full extent of an archaeological campaign (underwater mapping, diagnosis and cleaning tasks). The tools and methodologies developed within ARROWS comply with the "Annex" of the 2001 UNESCO Convention for the protection of Underwater Cultural Heritage (UCH). The system effectiveness and MARTA performance will be demonstrated in two scenarios, different as regards the environment and the historical context, the Mediterranean Sea (Egadi Islands) and the Baltic Sea

Global food security and food riots – an agent-based modelling approach

Due to negative consequences of climate change for agriculture and food production shocks affecting different areas of the world, the past two decades saw the conditions of global food security increasingly worsen. This has resulted in negative consequences for the world economy, partly causing international food price spikes and social upheavals. In this paper we present statistical findings along with a preliminary version of an original agent-based model called the Dawe Global Security Model that simulates the global food market and the political fragility of countries. The model simulates the effects of food insecurity on international food prices and how these, coupled with national political fragility and international food trade can, in turn, increase the probability of food riots in countries. The agents in the model are the 213 countries of the world whose characteristics reflect empirical data and the international trade of food is also simulated based on real trade partnerships and data. The model has been informed, calibrated and validated using real data and the results of these procedures are presented in the paper. To further test the model we also present the model’s forecasts for the near future in terms of food prices and incidence of food riots. The Dawe Global Security Model can be used to test scenarios on the evolution of shocks to global food production and analyse consequences for food riots. Further developments of the model can include national responses to food crises to investigate how countries can influence the spread of global food crises