Is organic diet really necessary for children?

The presentation focuse on the impact of pesticides on growing organisms, such as infants and young childre

Pediatric liver diseases: current challenges and future perspectives

Chronic liver diseases in children represent a rising problem with significant effects on public health. In fact, several pediatric liver diseases are precursors of adult chronic hepatopathies, cirrhosis and hepatocellular carcinoma. The prevalence of liver diseases in children is unknown. In the USA, every year, 15,000 children are hospitalized for liver diseases, but these disorders continue to be under-recognized or diagnosed late. The main reason is due to the frequent absence of symptoms in the vast majority of liver diseases, especially in the early stages. In the last few decades several advances have been made in understanding the pathogenesis of liver diseases, permitting the discovery of new therapeutic targets to treat liver diseases, thus improving the natural history of these disorders. In this article we discuss the most recent advances in the understanding of the pathogenesis, diagnosis and treatment of the most frequent pediatric liver diseases

Accuracy in the Identification of a Generator Thermal Bow

Model-based diagnostic techniques can be used to identify the faults that affect rotating machines. In general, the most important faults and malfunctions can be modelled by means of a suitable set of equivalent excitations that are applied to the nodes of a finite element model of the machine rotor train. Weighted least-squares error methods can be used to identify the set of forces and moments that minimize the error between experimental transient vibrations and the rotor system response obtained with the simulating model. However, the accuracy of the fault identification can be significantly influenced by the adequacy of the fault model as well as by the accuracy of the rotating machine model. This paper shows some methods, based on basic statistics, which enable the accuracy of the fault identification to be evaluated. The capabilities of the proposed methods have been proved by the results of the identification of the shaft thermalbow of a power unit generator that exhibited abnormal vibrations during machine coastdowns. The accuracy with which the location and the severity of the fault have been estimated is analyzed. In addition to this, the results obtained by the identification of the actual faults have been compared with those provided by the identification of false faults that cause similar symptoms

Climate resilient development index: theoretical framework, selection criteria and fit for purpose indicators

This report aims to contribute to the debate on climate change policies and their link to development. A climate resilient perspective is adopted to understand how climate change policy objectives can be reconciled with development goals. The report reviews the main theoretical concepts that characterise the scientific literature on climate risk and vulnerability assessments, and identifies climate resilient fit-for-purpose indicators accordingly. This makes it possible to build the theoretical foundations to improve understanding of the implications of climate aid financing. The novelty of this report lies in the emphasis given to economic aspects of climate risk, most notably: the concepts of loss and damage, the understanding of factors that enhance economic resilience, the links between climate change policies and development (besides economic growth) and the acknowledgment of the role of natural capital in pursuing development policies. By reviewing grey and peer-reviewed literature, 102 suitable indicators are identified and grouped into six components. A case study is proposed which involves building three climate resilient development indices. The three indices are built for climate resilient development using the same components and indicators but adopting different political perspectives. Our case study demonstrates that although there is some agreement on which indicators should be included in an index for climate resilient development, a single approach to building a global index for climate resilient development does not exist. The high number of differences between the scores of the three indices indicates that a single index in the climate resilient development domain is a sort of chimera. Any index should address a specific policy request with a clear objective. This is a first step to building a fit-for-purpose index.JRC.H.7-Climate Risk Managemen

Analysis of the Instability Phenomena Caused by Steam in High-pressure Turbines

Instability phenomena in steam turbines may happen as a consequence of certain characteristics of the steam flow as well as of the mechanical and geometrical properties of the seals. This phenomenon can be modeled and the raise of the steam flow and pressure causes the increase of the cross coupled coefficients used to model the seal stiffness. As a consequence, the eigenvalues and eigenmodes of the mathematical model of the machine change. The real part of the eigenvalue associated with the first flexural normal mode of the turbine shaft may become positive causing the conditions for unstable vibrations. The original contribution of the paper is the application of a model-based analysis of the dynamic behavior of a large power unit, affected by steam-whirl instability phenomena. The model proposed by the authors allows studying successfully the experimental case. The threshold level of the steam flow that causes instability conditions is analyzed and used to define the stability margin of the power unit

APPLICATION OF SQUEEZE FILM DAMPERS

The level of the vibrations and the presence of instability are the two most critical aspects regarding the operations of turbomachinery. To cope with this issues that may compromise the operation of the machines, squeeze film dampers (SFD) are often used in many industrial applications. Unfortunately, many complex phenomena characterize the dynamic behavior of these compo-nents and determine the high complexity of the modeling of these components. The most relevant phenomena involved in the characterization of SFDs are indi-viduated after a comprehensive investigation of the state of the art. Among them, the oil film cavitation, the air ingestion, and the effect of the inertia are intro-duced. A modeling strategy based on the Reynolds equation is then presented. The boundary conditions to be adopted for the feeding and discharging of oil are investigated and implemented. Eventually, the finite difference model is applied to a practical example to evaluate the possibility to minimize the vibration level and to reduce the effect of the instability if a SFD is added to a rotodynamic system. Meaningful information about the modeling of SFDs is provided in this work. The critical aspects of these components and their modeling are high-lighted and discussed

Thermally Induced Vibrations due to Rub in Real Rotors

The analysis of the effects of the rotor-to-stator rub in the rotor dynamics field has produced many models, often nonlinear or with particular attention to chaotic behaviour, but with scarce correspondence with real rotors since Jeffcott-like rotors are mainly used without thermal transients, or sometimes real rotors are used but with very simple thermal modelling. One of the most remarkable aspects of the rotor-to-stator rub at operating speed is the possibility of observing spiral vibration phenomena in the synchronous vibration, i.e. the vibration vector changes its amplitude and rotates even at the rated speed. This is due to the combined effect of the contact forces which introduce heat and of the resulting thermal bow. The phenomenon is also called vector turning or thermally induced vibrations. It is interesting to analyse the dynamical behaviour of the machine: the spirals can have a self-propagating trend or conversely a self-correcting trend. The model presented in the paper for the analysis of the spiral vibration has a unique characteristic in that it allows real machines to be analysed, since it uses a fully assembled machine model (rotor, bearings and foundation) and implements a rather sophisticated thermal and contact model. The experimental validation of the proposed model is performed on data coming from a real machine: the generator of a 50 MW combined cycle power plant, in which unstable spiral vibrations were observed at the operating speed during a power increase

Estrategias de lectura para la identificación de la idea central de textos expositivos

El presente estudio tiene como finalidad identificar las estrategias de lectura que utilizan algunos estudiantes de una institución preuniversitaria de Lima para hallar la idea central en textos expositivos y comprender cómo las usan. Para ello, mediante un método cualitativo y un diseño metodológico epistemológico realista, se entrevistó a 12 estudiantes que cursaban el ciclo regular 2021 de abril-julio de la institución y que postulaban a carreras de Ciencias. Fueron divididos en dos grupos: alto rendimiento (n=8) y bajo rendimiento (n=4) en comprensión de lectura según los resultados de un subtest de comprensión de lectura. Las entrevistas se llevaron a cabo luego de que el estudiante leyera un texto asignado con el fin de indagar sobre las estrategias de lectura que se activaron en dicho proceso. Se analizó el contenido de la transcripción de las entrevistas por medio del software Atlas.ti. Los resultados evidenciaron que los estudiantes de bajo rendimiento, a diferencia de los de alto rendimiento, no usaron estrategias de lectura para reconstruir la idea central de un texto expositivo, ni ajustaron sus estrategias de lectura al propósito de la tarea, ni al tipo de texto, ni a sus características textuales, sino que activaron procesos poco eficaces para la tarea. Asimismo, leían de manera literal, mostraron un menor nivel de dominio de la lectura, insuficientes destrezas de la memoria de trabajo y en sus procesos metacognitivos, así como baja motivación, autoeficacia y gusto por la lectura.The present study aimed to identify reading strategies used by students from a pre-university institute in Lima for the purpose of finding the main idea of an expository text, and to comprehend how they use these strategies. A qualitative method and an epistemological realistic design were used to interview 12 students from the April-July, 2021 regular program, who were applying for science careers. The interviewed students were divided into two groups according to the outcome attained in a reading comprehension subtest: high achieving (n = 8) and poor achieving students (n = 4). Each interview was carried out just after the student had read an assigned text, in order to inquire about the reading strategies that were activated in their mental process while reading this text. Interviews’ transcripts were content analyzed using the Atlas.ti software. Results showed that poor-achieving students, unlike the high-achieving students, did not use reading comprehension strategies to find the main idea of an expository text, nor did they adjust their reading to the purpose of the task, nor to the type and characteristics of the text, but rather activated processes that were not efficient for the task. Likewise, they reached just a literal reading level, that showed an elementary reading development level, insufficient working memory skills and metacognitive processes, as well as, low motivation, poor self-efficacy and little enjoyment of reading