Aprendiendo racismo. Racismo estructural en libros de texto

La hipótesis de este trabajo es que la educación formal es uno de los espacios donde se transmiten las representaciones e instituciones que mantienen y refuerzan el racismo estructural. Para investigar esta hipótesis hemos seleccionado los libros de historia utilizados en los 4 años de la Educación Secundaria Obligatoria (ESO) de las dos principales editoriales españolas: Anaya y Santillana. A partir de la lectura de estos libros hemos buscado los indicios de los elementos que pueden ser responsables del mantenimiento de representaciones e instituciones sociales que validan y fortalecen el racismo estructural en las sociedades modernas, y específicamente en la España actual.Fac. de Ciencias Políticas y SociologíaTRUEpu

Extrato hidroalcoólico de rosela (Hibiscus sabdariffa L.) na alimentação do peixe Mato Grosso (Hyphessobrycon eques)

This study evaluated the inclusion of hydroalcoholic rosela extract (Hibiscus sabdariffa) in diets of the thick-bush fish (Hyphessobrycon eques).  120 fish (0.51± 0.06 g), were randomly distributed in 12 polyethylene aquariums of 20L, in a water recirculation system, with the storage density of 10 fish per aquarium. Fish were fed for 21 days per diet (40.88% CP and 4374.8 Kcal kg-1), plus rosela alcohol extract (control; 0.12; 0.25 and 0.50mg of EHR/kg of feed). The inclusion of concentrations of 0.25 and 0.50 EHR/kg promoted an improvement in zootechnical indices, in weight gain, total length, standard length and feed conversion. The fish presented alteration of chroma a*(shades of green and red), there was no increase in intensity in relation to chroma b* luminosity (shades of blue and yellow). The use of 0.25 and 0.50 EHR/kg reflected decreased activity of AST and ALT enzymes. An increase in catalase activity was observed in concentrations with higher rates of hydroalcoholic rosela extracts in the diet. The hydroalcoholic extract of Rosela is efficient in feeding Mato Grosso at the concentration of 0.50 mg EHR/kg.O objetivo deste estudo foi avaliar a inclusão do extrato hidroalcoólico de rosela (Hibiscus sabdariffa) em dietas do peixe Mato Grosso (Hyphessobrycon eques). Foram utilizados 120 peixes (0,51± 0,06 g), que foram distribuídos aleatoriamente em 12 aquários de polietileno de 20L, em sistema de recirculação de água, com a densidade de estocagem de 10 peixes por aquário. Os peixes foram alimentados por 21 dias com uma dieta (40,88% PB e 4374,8 Kcal kg-1), acrescida de extrato hidroalcoólico de rosela - EHR (controle; 0,12; 0,25 e 0,50 mg de EHR/kg de ração). A inclusão de concentração de 0,25 e 0,50 EHR/kg, promoveu uma melhora nos índices zootécnicos, comprimento padrão e eficiência alimentar. Os peixes apresentaram alteração de croma a*(tonalidades de verde e vermelho), entretanto, não houve aumento de intensidade em relação à luminosidade croma b* (tonalidades de azul e amarelo). A utilização de 0,25 e 0,50 EHR/kg refletiu em diminuição da atividade das enzimas AST e ALT. Observou-se o aumento da atividade catalase em concentrações com maiores índices de extratos hidroalcoólicos de rosela na dieta. O extrato hidroalcoólico de rosela é eficiente na alimentação de peixe Mato Grosso na concentração de 0,50 mg EHR/kg

Extrato hidroalcoólico de rosela (Hibiscus sabdariffa L.) na alimentação do peixe Mato Grosso (Hyphessobrycon eques)

O objetivo deste estudo foi avaliar a inclusão do extrato hidroalcoólico de rosela (Hibiscus sabdariffa) em dietas do peixe Mato Grosso (Hyphessobrycon eques). Foram utilizados 120 peixes (0,51± 0,06 g), que foram distribuídos aleatoriamente em 12 aquários de polietileno de 20L, em sistema de recirculação de água, com a densidade de estocagem de 10 peixes por aquário. Os peixes foram alimentados por 21 dias com uma dieta (40,88% PB e 4374,8 Kcal kg-1), acrescida de extrato hidroalcoólico de rosela - EHR (controle; 0,12; 0,25 e 0,50 mg de EHR/kg de ração). A inclusão de concentração de 0,25 e 0,50 EHR/kg, promoveu uma melhora nos índices zootécnicos, comprimento padrão e eficiência alimentar. Os peixes apresentaram alteração de croma a*(tonalidades de verde e vermelho), entretanto, não houve aumento de intensidade em relação à luminosidade croma b* (tonalidades de azul e amarelo). A utilização de 0,25 e 0,50 EHR/kg refletiu em diminuição da atividade das enzimas AST e ALT. Observou-se o aumento da atividade catalase em concentrações com maiores índices de extratos hidroalcoólicos de rosela na dieta. O extrato hidroalcoólico de rosela é eficiente na alimentação de peixe Mato Grosso na concentração de 0,50 mg EHR/kg

Overview of recent TJ-II stellarator results

The main results obtained in the TJ-II stellarator in the last two years are reported. The most important topics investigated have been modelling and validation of impurity transport, validation of gyrokinetic simulations, turbulence characterisation, effect of magnetic configuration on transport, fuelling with pellet injection, fast particles and liquid metal plasma facing components. As regards impurity transport research, a number of working lines exploring several recently discovered effects have been developed: the effect of tangential drifts on stellarator neoclassical transport, the impurity flux driven by electric fields tangent to magnetic surfaces and attempts of experimental validation with Doppler reflectometry of the variation of the radial electric field on the flux surface. Concerning gyrokinetic simulations, two validation activities have been performed, the comparison with measurements of zonal flow relaxation in pellet-induced fast transients and the comparison with experimental poloidal variation of fluctuations amplitude. The impact of radial electric fields on turbulence spreading in the edge and scrape-off layer has been also experimentally characterized using a 2D Langmuir probe array. Another remarkable piece of work has been the investigation of the radial propagation of small temperature perturbations using transfer entropy. Research on the physics and modelling of plasma core fuelling with pellet and tracer-encapsulated solid-pellet injection has produced also relevant results. Neutral beam injection driven Alfvénic activity and its possible control by electron cyclotron current drive has been examined as well in TJ-II. Finally, recent results on alternative plasma facing components based on liquid metals are also presentedThis work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014–2018 under Grant Agreement No. 633053. It has been partially funded by the Ministerio de Ciencia, Inovación y Universidades of Spain under projects ENE2013-48109-P, ENE2015-70142-P and FIS2017-88892-P. It has also received funds from the Spanish Government via mobility grant PRX17/00425. The authors thankfully acknowledge the computer resources at MareNostrum and the technical support provided by the Barcelona S.C. It has been supported as well by The Science and Technology Center in Ukraine (STCU), Project P-507F

Investigation of the magnetic topology of helical RFP plasmas

The work carried out during these three years is part of the research activity on controlled thermonuclear fusion as a (future) energy source that would meet the requirements of a clean, renewable and abundant resource. Fusion reactions are well known to physicists since 1930 and the ambitious idea is to reproduce in laboratory the process that powers the Sun and all the stars. Its reproduction on Earth in a fusion reactor is limited by the inability of confining high density and temperature plasmas, necessary to overcome the Coulomb repulsion between nuclei and bring the reactants within the range of their strong interaction. Civil research is mainly devoted to the study of magnetic plasma confinements. Presently Tokamak, Stellarator and Reversed Field Pinch (RFP) configurations are the most explored magnetic configurations, the first two being the most promising for a fusion reactor (the ITER Tokamak in Cadarache, France, and the Wendelstein--7X Stellarator in Greifswald, Germany, are now under construction as the next step in fusion research). The study of the reversed field pinch configuration is getting new momentum from recent results, and this thesis has been carried out in the largest RFP device in the world, which is in operation in Padova, Italy, since 1990: the RFX--mod device (previously called RFX). RFPs are Ohmically heated devices, with high currents flowing in the plasma. In the past, their performance has been limited by the intrinsic presence of many instabilities that degrade the confinement. At present, new high--plasma--current (higher than 1.5 MA in RFX--mod) states have been discovered, which show that as the plasma becomes hotter it spontaneously undergoes a transition to a state with improved confinement properties due to the emergence of an ordered spontaneous magnetic structure in the otherwise chaotic core. These states (named SHAx, Single Helical Axis) are characterized by magnetic surfaces winding around a helical axis and are therefore considered as the helical RFP states. The aim of this thesis is to investigate and model the magnetic topology related to helical SHAx state equilibria, taking into account both the core region and the edge. As a first step, new helical coordinates to well describe the helical shape of SHAx states on a torus has been defined. This has been carried out making use of the curvilinear metrics theory (to well consider the toroidicity of the helical system) and Hamiltonian mechanics tools applied to magnetic field (to make use of action--angle as a smart choice of coordinates). The practical outcome of this thesis is the code named SHEq (Single Helical Equilibria), which uses the complete definition of the helical metrics to compute all the (helical) equilibrium plasma quantities and can be therefore useful to interpret the data from different diagnostics. Furthermore, this should allow to verify if the equilibrium satisfies the Ohmic constraint, \emph{a posteriori} since the Ohm's law is not an initial constraint for SHEq's equilibrium reconstruction. This highlights that SHEq's equilibria are not steady state, and a part of this thesis has been carried out in collaboration with the Theory Group of TJ-II (Ciemat, Madrid), where I worked for about three months, in order to evolve in time helical equilibria accordingly to Ohm's law too. Finally, a more experimental part of the thesis concerns the edge region. From the point of view of plasma--wall interaction SHAx states appears with a regular helical pattern and a part of this thesis is also devoted to the study of some discharges (done during the 2011 RFX--mod experimental campaign) where particular boundary conditions were applied in order to favor and sustain both the helical deformation in the core and a more regular helical pattern in the plasma--wall interaction.Questa tesi si inserisce nel contesto della ricerca sulla fusione termonucleare controllata come possibile fonte alternativa di energia. La fusione il processo che alimenta il sole e tutte le altre stelle attive, il progetto quello di riprodurre questo processo in macchine da laboratorio: il progetto, affascinante ma di non facile realizzazione, si scontra soprattutto con la difficolt di confinare alte temperature e densit di plasma, stato ionizzato della materia (il cosiddetto quarto stato della materia). La ricerca civile in questo campo quasi interamente dedicata allo studio del confinamento dei plasmi da fusione con campi magnetici. Le configurazioni di campo magnetico pi studiate sono quelle dette Tokamak, Stellarator e Reversed--Field--Pinch (RFP), che confinano i plasmi in macchine toroidali. Tokamak e Stellarator sono le configurazioni che storicamente hanno dato i migliori risultati in termini di confinamento di particelle ed energia: vanno ricordati rispettivamente i due progetti per la futura generazione delle macchine da fusione, ITER (progetto di collaborazione internazionale oggi in costruzione a Cadarache, Francia) e Wendelstein--7X (progetto in costruzione a Greifswald, Germania). Per quanto riguarda il RFP, il pi grande esperimento oggi attivo l'esperimento RFX (oggi RFX--mod), in funzione a Padova dal 1990, dove si svolto questo lavoro di tesi. Nei RFP il plasma riscaldato per effetto ohmico da un'alta corrente che fluisce nel plasma, ma la presenza di molte instabilit, considerate intrinseche alla configurazione, ha storicamente condotto a bassi tempi di confinamento e quindi a poca fiducia nel RFP come possibile configurazione per un reattore. La ricerca su questo tipo di macchine oggi rivalutata da nuovi risultati, che dimostrano come all'aumentare della corrente il plasma spontaneamente si porti in uno stato meno caotico con propriet di confinamento migliorate. Questi stati sono chiamati SHAx (Single Helical Axis) perch caratterizzati da superfici magnetiche elicoidali. Obiettivo di questa tesi lo studio e la caratterizzazione della topologia magnetica degli equilibri SHAx (in RFX--mod ottenuti per correnti di plasma superiori a 1.5 MA), sia nella regione centrale del plasma (plasma core) che nella zona di bordo dove dominano gli effetti dell'interazione plasma--parete (plasma edge). Il primo passo per caratterizzare i nuovi equilibri elicoidali stato la ricerca di buone coordinate elicoidali. Si fatto uso per questo di coordinate curvilinee (per descrivere la geometria toroidale del sistema) e della meccanica hamiltoniana applicata ai campi magnetici in un toro (il che permette di usare le coordinate azione--angolo del sistema). Il risultato di questo studio un codice (SHEq, Single Helical Equilibria) che usa le metriche elicoidali per la ricostruzione delle quantit\`a di plasma (componenti del campo o dei flussi magnetici e della densit di corrente) durante gli stati SHAx, ed quindi per esempio utile per interpretare i dati sperimentali delle varie diagnostiche. Parte di questa tesi si svolta in collaborazione con il gruppo di Teoria di TJ--II (Ciemat, Madrid) per l'evoluzione temporale degli equilibri elicoidali di SHEq in accordo con la legge di Ohm (che non iniziale vincolo). La parte pi sperimentale di questa tesi riguarda lo studio della zona di bordo dove un'interazione regolare del plasma con la parete riflette la deformazione elicoidale della colonna di plasma. Una parte del tempo nella campagna sperimentale 2011 di RFX--mod stata dedicata allo studio di particolari condizioni al contorno per favorire e controllare la regolarit dell'interazione plasma--parete

Description of magnetic field lines without arcana

International audienceThis work is based on the variational principle for magnetic field lines introduced in 1983 by Cary and Littlejohn. The action principles for magnetic field lines and for Hamiltonian mechanics are recalled to be analogous. It is shown that the first one can be rigorously proved from first principles without analytical calculations. Not only the action principles are analogous, but also a change of canonical coordinates is recalled to be equivalent to a change of gauge. Furthermore, using the vector potential makes obvious the freedom in the choice of "time" for describing Hamiltonian dynamics. These features may be used for a new pedagogical and intuitive introduction to Hamiltonian mechanics. In the context of confined magnetic fields, the action principle for magnetic field lines makes practical calculations simpler and safer, with an intuitive background. In particular, with a new analytical result: the width of a magnetic island is proportional to the square root of an invariant flux related to this island, the magnetic flux through a ribbon whose edges are the field lines related to the O and X points of the island. This is the first expression of this width avoiding abstract Fourier components and obviously independent of the choice of coordinates. The same analytical calculation provides a simple way to compute numerically the width of a magnetic island. Also to apply Chirikov resonance overlap criterion. Moreover, a new formula provides explicitly the Boozer and Hamada magnetic coordinates from action-angle coordinates