Análise isocinética da articulação do cotovelo em crianças com paralisia cerebral

A quantidade de torque aplicado na articulação é uma medida de aptidão física importante para crianças com paralisia cerebral. O presente estudo analisou parâmetros cinéticos na articulação do cotovelo em crianças saudáveis e com paralisia cerebral. Participaram 10 crianças com paralisia cerebral e 10 crianças sem comprometimento neurológico. Avaliou-se a média do pico de torque, média do ângulo do pico de torque, coeficiente de variação do torque e aceleração angular do movimento de flexo-extensão do cotovelo nas velocidades com um dinamômetro isocinético. A média de pico de torque (extensão), aceleração (flexão) e coeficiente de variação (flexão e extensão) são diferentes entre grupos. Conclui-se que o torque e aceleração sofreram interferências no movimento de flexo-extensão; as principais diferenças encontradas foram entre os extremos das velocidades; não houve diferenças no ângulo do pico de torque. A espasticidade não interferiu na força dos músculos agonistas do movimento de flexão da articulação do cotovelo.

Evaluation of vertical forces in the pads of Pitbulls with cranial cruciate ligament rupture

Background: Cranial cruciate ligament rupture (CCLR) is one of the most important stifle injuries and a common cause of lameness in dogs. Our objective was to measure the vertical forces in the pads of Pitbulls with cranial cruciate ligament rupture (CCLR) using a pressure sensitive walkway. A pressure sensitive walkway was used to collect vertical force data from the pads of 10 Pitbulls affected with unilateral CCLR. Ten healthy Pitbulls were included in the study as controls. Velocity varied between 1.3 and 1.6 m/s and acceleration was kept below ± 0.1 m/s2. Differences between groups and between pads in the same limb within groups were investigated using ANOVA and the Tukey test. The paired Student t-test was employed to assess gait symmetry (p < 0.05). Results: Peak vertical forces (PVF) were lower in the affected limb, particularly in the metatarsal pad. Increased PVF values in the forelimb and the contralateral hind limb pads of affected dogs suggest a compensatory effect. Conclusions: A consistent pattern of vertical force distribution was observed in the pads of dogs with CCLR. These data are important for increased understanding of vertical force distribution in the limb of dogs with CCLR disease. Kinetic analysis using pressure sensitive walkways can be useful in follow-up assessment of surgically treated dogs regardless of the surgical technique employed.

Stochastic gravito-inertial modes discovered by CoRoT in the hot Be star HD51452

Context. Be stars are rapidly rotating stars with a circumstellar decretion disk. They usually undergo pressure and/or gravity pulsation modes excited by the κ-mechanism, i.e. an effect of the opacity of iron-peak elements in the envelope of the star. In the Milky Way, p-modes are observed in stars that are hotter than or equal to the B3 spectral type, while g-modes are observed at the B2 spectral type and cooler. Aims. We observed a B0IVe star, HD51452, with the high-precision, high-cadence photometric CoRoT satellite and high-resolution, ground-based HARPS and SOPHIE spectrographs to study its pulsations in great detail. We also used the lower resolution spectra available in the BeSS database. Methods. We analyzed the CoRoT and spectroscopic data with several methods: Clean-NG, FreqFind, and a sliding window method. We also analyzed spectral quantities, such as the violet over red (V/R) emission variations, to obtain information about the variation in the circumstellar environment. We calculated a stellar structure model with the ESTER code to test the various interpretation of the results. Results. We detect 189 frequencies of variations in the CoRoT light curve in the range between 0 and 4.5 c d−1. The main frequencies are also recovered in the spectroscopic data. In particular we find that HD51452 undergoes gravito-inertial modes that are not in the domain of those excited by the κ-mechanism. We propose that these are stochastic modes excited in the convective zones and that at least some of them are a multiplet of r-modes (i.e. subinertial modes mainly driven by the Coriolis acceleration). Stochastically excited gravito-inertial modes had never been observed in any star, and theory predicted that their very low amplitudes would be undetectable even with CoRoT. We suggest that the amplitudes are enhanced in HD51452 because of the very rapid stellar rotation. In addition, we find that the amplitude variations of these modes are related to the occurrence of minor outbursts. Conclusions. Thanks to CoRoT data, we have detected a new kind of pulsations in HD51452, which are stochastically excited gravito-inertial modes, probably due to its very rapid rotation. These modes are probably also present in other rapidly rotating hot Be stars.

Type Ia Supernovae : Homogeneity and Diversity

The use of type Ia supernovae as distance estimators has shown that about 75% of the energy content of the universe has a negative equation of state parameter and thus, drives the acceleration of the universe. Constraining the exact nature of this energy is one of the main goals in cosmology. As the statistics of observed high-redshift supernovae increases, systematic effects become the limiting factor to pursue such investigations, thus deeper understanding of the physical properties of SNe is of great importance. In this thesis we investigate spectral homogeneity and diversity of local and high redshift supernovae. Special emphasis has been given to the analysis of optical spectra of local peculiar supernovae 1999aa and 1999ac. The study of the spectra of SN 1999aa pointed out that this SN could be a link between the extreme peculiar SN 1991T and normal SNe. Moreover, the identification of a high velocity component of Ca II and possibly of a low velocity component of C III suggests some degree of asphericity in the ejecta of this supernova. Evidence for a deflagration of a C+O white dwarf was found in the early spectra of SN 1999ac. The spectral proprieties of a vast sample of local SNe are also studied by means of newly introduced spectral indicators. These were used to possibly improve the intrinsic spread of SN peak magnitudes to 0.15 mag, independently of light curve parameters. The first quantitative comparison between local and high redshift supernova is carried out. No evidence for extreme peculiar sub-luminous SNe was found in our data set including 13 SNe with redshift range z=0.279-0.912. Furthermore, SN2002fd (z=0.279) was found to show spectral characteristics similar to SN 1991T/SN 1999aa-like supernovae. We also present a feasibility study of the Hubble diagram in rest frame I-band up to z~0.5, and show the possibility to probe the presence of intergalactic dust, which could possibly mimic the effect of dark energy in the Hubble diagram.

Contador de repeticiones en ejercicios

[ES] Aplicación para dispositivos móviles Android que, ayudada por acelerómetros y giroscopios, da soporte al desarrollo de actividades físicas que necesiten un plan de trabajo basado en repeticiones y rutinas de ejercicios. El App ayuda a contabilizar las repeticiones de cada ejercicio, informando al usuario mediante sonido, para que este pueda mantener un ritmo continuo. El App permite la realización de ejercicios individuales hasta alcanzar un número objetivo de repeticiones o repeticiones libres; o permite la realización de una serie de ejercicios que forman parte de una rutina de ejercicios. Es posible crear rutinas de ejercicios personalizadas, eliminar rutinas o editar rutinas ya existentes (añadiendo o eliminando ejercicios y repeticiones). El reconocimiento de movimientos para la contabilización de repeticiones se realiza usando el valor absoluto del vector de aceleración generado a partir de los datos del acelerómetro del dispositivo. Este método, aunque no permite la precisión de reconocimiento de movimientos que permitiría el modelado tridimensional de la aceleración lineal del dispositivo, permite un reconocimiento menos computacionalmente costoso, ignorando ciertos factores exteriores y sin la necesidad de entrenamiento previo de la aplicación.

Procedimenti di ottimizzazione di sistemi smorzati

La presente tesi riguarda lo studio di procedimenti di ottimizzazione di sistemi smorzati. In particolare, i sistemi studiati sono strutture shear-type soggette ad azioni di tipo sismico impresse alla base. Per effettuare l’ottimizzazione dei sistemi in oggetto si agisce sulle rigidezze di piano e sui coefficienti di smorzamento effettuando una ridistribuzione delle quantità suddette nei piani della struttura. È interessante effettuare l’ottimizzazione di sistemi smorzati nell’ottica della progettazione antisismica, in modo da ridurre la deformata della struttura e, conseguentemente, anche le sollecitazioni che agiscono su di essa. Il lavoro consta di sei capitoli nei quali vengono affrontate tre procedure numerico-analitiche per effettuare l’ottimizzazione di sistemi shear-type. Nel primo capitolo si studia l’ottimizzazione di sistemi shear-type agendo su funzioni di trasferimento opportunamente vincolate. In particolare, le variabili di progetto sono le rigidezze di piano, mentre i coefficienti di smorzamento e le masse di piano risultano quantità note e costanti durante tutto il procedimento di calcolo iterativo; per effettuare il controllo dinamico della struttura si cerca di ottenere una deformata pressoché rettilinea. Tale condizione viene raggiunta ponendo le ampiezze delle funzioni di trasferimento degli spostamenti di interpiano pari all’ampiezza della funzione di trasferimento del primo piano. Al termine della procedura si ottiene una ridistribuzione della rigidezza complessiva nei vari piani della struttura. In particolare, si evince un aumento della rigidezza nei piani più bassi che risultano essere quelli più sollecitati da una azione impressa alla base e, conseguentemente, si assiste ad una progressiva riduzione della variabile di progetto nei piani più alti. L’applicazione numerica di tale procedura viene effettuata nel secondo capitolo mediante l’ausilio di un programma di calcolo in linguaggio Matlab. In particolare, si effettua lo studio di sistemi a tre e a cinque gradi di libertà. La seconda procedura numerico-analitica viene presentata nel terzo capitolo. Essa riguarda l’ottimizzazione di sistemi smorzati agendo simultaneamente sulla rigidezza e sullo smorzamento e consta di due fasi. La prima fase ricerca il progetto ottimale della struttura per uno specifico valore della rigidezza complessiva e dello smorzamento totale, mentre la seconda fase esamina una serie di progetti ottimali in funzione di diversi valori della rigidezza e dello smorzamento totale. Nella prima fase, per ottenere il controllo dinamico della struttura, viene minimizzata la somma degli scarti quadratici medi degli spostamenti di interpiano. Le variabili di progetto, aggiornate dopo ogni iterazione, sono le rigidezze di piano ed i coefficienti di smorzamento. Si pone, inoltre, un vincolo sulla quantità totale di rigidezza e di smorzamento, e i valori delle rigidezze e dei coefficienti di smorzamento di ogni piano non devono superare un limite superiore posto all’inizio della procedura. Anche in questo caso viene effettuata una ridistribuzione delle rigidezze e dei coefficienti di smorzamento nei vari piani della struttura fino ad ottenere la minimizzazione della funzione obiettivo. La prima fase riduce la deformata della struttura minimizzando la somma degli scarti quadrarici medi degli spostamenti di interpiano, ma comporta un aumento dello scarto quadratico medio dell’accelerazione assoluta dell’ultimo piano. Per mantenere quest’ultima quantità entro limiti accettabili, si passa alla seconda fase in cui si effettua una riduzione dell’accelerazione attraverso l’aumento della quantità totale di smorzamento. La procedura di ottimizzazione di sistemi smorzati agendo simultaneamente sulla rigidezza e sullo smorzamento viene applicata numericamente, mediante l’utilizzo di un programma di calcolo in linguaggio Matlab, nel capitolo quattro. La procedura viene applicata a sistemi a due e a cinque gradi di libertà. L’ultima parte della tesi ha come oggetto la generalizzazione della procedura che viene applicata per un sistema dotato di isolatori alla base. Tale parte della tesi è riportata nel quinto capitolo. Per isolamento sismico di un edificio (sistema di controllo passivo) si intende l’inserimento tra la struttura e le sue fondazioni di opportuni dispositivi molto flessibili orizzontalmente, anche se rigidi in direzione verticale. Tali dispositivi consentono di ridurre la trasmissione del moto del suolo alla struttura in elevazione disaccoppiando il moto della sovrastruttura da quello del terreno. L’inserimento degli isolatori consente di ottenere un aumento del periodo proprio di vibrare della struttura per allontanarlo dalla zona dello spettro di risposta con maggiori accelerazioni. La principale peculiarità dell’isolamento alla base è la possibilità di eliminare completamente, o quantomeno ridurre sensibilmente, i danni a tutte le parti strutturali e non strutturali degli edifici. Quest’ultimo aspetto è importantissimo per gli edifici che devono rimanere operativi dopo un violento terremoto, quali ospedali e i centri operativi per la gestione delle emergenze. Nelle strutture isolate si osserva una sostanziale riduzione degli spostamenti di interpiano e delle accelerazioni relative. La procedura di ottimizzazione viene modificata considerando l’introduzione di isolatori alla base di tipo LRB. Essi sono costituiti da strati in elastomero (aventi la funzione di dissipare, disaccoppiare il moto e mantenere spostamenti accettabili) alternati a lamine in acciaio (aventi la funzione di mantenere una buona resistenza allo schiacciamento) che ne rendono trascurabile la deformabilità in direzione verticale. Gli strati in elastomero manifestano una bassa rigidezza nei confronti degli spostamenti orizzontali. La procedura di ottimizzazione viene applicata ad un telaio shear-type ad N gradi di libertà con smorzatori viscosi aggiunti. Con l’introduzione dell’isolatore alla base si passa da un sistema ad N gradi di libertà ad un sistema a N+1 gradi di libertà, in quanto l’isolatore viene modellato alla stregua di un piano della struttura considerando una rigidezza e uno smorzamento equivalente dell’isolatore. Nel caso di sistema sheat-type isolato alla base, poiché l’isolatore agisce sia sugli spostamenti di interpiano, sia sulle accelerazioni trasmesse alla struttura, si considera una nuova funzione obiettivo che minimizza la somma incrementata degli scarti quadratici medi degli spostamenti di interpiano e delle accelerazioni. Le quantità di progetto sono i coefficienti di smorzamento e le rigidezze di piano della sovrastruttura. Al termine della procedura si otterrà una nuova ridistribuzione delle variabili di progetto nei piani della struttura. In tal caso, però, la sovrastruttura risulterà molto meno sollecitata in quanto tutte le deformazioni vengono assorbite dal sistema di isolamento. Infine, viene effettuato un controllo sull’entità dello spostamento alla base dell’isolatore perché potrebbe raggiungere valori troppo elevati. Infatti, la normativa indica come valore limite dello spostamento alla base 25cm; valori più elevati dello spostamento creano dei problemi soprattutto per la realizzazione di adeguati giunti sismici. La procedura di ottimizzazione di sistemi isolati alla base viene applicata numericamente mediante l’utilizzo di un programma di calcolo in linguaggio Matlab nel sesto capitolo. La procedura viene applicata a sistemi a tre e a cinque gradi di libertà. Inoltre si effettua il controllo degli spostamenti alla base sollecitando la struttura con il sisma di El Centro e il sisma di Northridge. I risultati hanno mostrato che la procedura di calcolo è efficace e inoltre gli spostamenti alla base sono contenuti entro il limite posto dalla normativa. Giova rilevare che il sistema di isolamento riduce sensibilmente le grandezze che interessano la sovrastruttura, la quale si comporta come un corpo rigido al di sopra dell’isolatore. In futuro si potrà studiare il comportamento di strutture isolate considerando diverse tipologie di isolatori alla base e non solo dispositivi elastomerici. Si potrà, inoltre, modellare l’isolatore alla base con un modello isteretico bilineare ed effettuare un confronto con i risultati già ottenuti per il modello lineare.

Centrifuge Modeling of Sandy Slopes

Slope failure occurs in many areas throughout the world and it becomes an important problem when it interferes with human activity, in which disasters provoke loss of life and property damage. In this research we investigate the slope failure through the centrifuge modeling, where a reduced-scale model, N times smaller than the full-scale (prototype), is used whereas the acceleration is increased by N times (compared with the gravity acceleration) to preserve the stress and the strain behavior. The aims of this research “Centrifuge modeling of sandy slopes” are in extreme synthesis: 1) test the reliability of the centrifuge modeling as a tool to investigate the behavior of a sandy slope failure; 2) understand how the failure mechanism is affected by changing the slope angle and obtain useful information for the design. In order to achieve this scope we arranged the work as follows: Chapter one: centrifuge modeling of slope failure. In this chapter we provide a general view about the context in which we are working on. Basically we explain what is a slope failure, how it happens and which are the tools available to investigate this phenomenon. Afterwards we introduce the technology used to study this topic, that is the geotechnical centrifuge. Chapter two: testing apparatus. In the first section of this chapter we describe all the procedures and facilities used to perform a test in the centrifuge. Then we explain the characteristics of the soil (Nevada sand), like the dry unit weight, water content, relative density, and its strength parameters (c,φ), which have been calculated in laboratory through the triaxial test. Chapter three: centrifuge tests. In this part of the document are presented all the results from the tests done in centrifuge. When we talk about results we refer to the acceleration at failure for each model tested and its failure surface. In our case study we tested models with the same soil and geometric characteristics but different angles. The angles tested in this research were: 60°, 75° and 90°. Chapter four: slope stability analysis. We introduce the features and the concept of the software: ReSSA (2.0). This software allows us to calculate the theoretical failure surfaces of the prototypes. Then we show in this section the comparisons between the experimental failure surfaces of the prototype, traced in the laboratory, and the one calculated by the software. Chapter five: conclusion. The conclusion of the research presents the results obtained in relation to the two main aims, mentioned above.

Improved ground motion intensity measures for reliability-based demand analysis of structures

In Performance-Based Earthquake Engineering (PBEE), evaluating the seismic performance (or seismic risk) of a structure at a designed site has gained major attention, especially in the past decade. One of the objectives in PBEE is to quantify the seismic reliability of a structure (due to the future random earthquakes) at a site. For that purpose, Probabilistic Seismic Demand Analysis (PSDA) is utilized as a tool to estimate the Mean Annual Frequency (MAF) of exceeding a specified value of a structural Engineering Demand Parameter (EDP). This dissertation focuses mainly on applying an average of a certain number of spectral acceleration ordinates in a certain interval of periods, Sa,avg (T1,…,Tn), as scalar ground motion Intensity Measure (IM) when assessing the seismic performance of inelastic structures. Since the interval of periods where computing Sa,avg is related to the more or less influence of higher vibration modes on the inelastic response, it is appropriate to speak about improved IMs. The results using these improved IMs are compared with a conventional elastic-based scalar IMs (e.g., pseudo spectral acceleration, Sa ( T(¹)), or peak ground acceleration, PGA) and the advanced inelastic-based scalar IM (i.e., inelastic spectral displacement, Sdi). The advantages of applying improved IMs are: (i ) "computability" of the seismic hazard according to traditional Probabilistic Seismic Hazard Analysis (PSHA), because ground motion prediction models are already available for Sa (Ti), and hence it is possibile to employ existing models to assess hazard in terms of Sa,avg, and (ii ) "efficiency" or smaller variability of structural response, which was minimized to assess the optimal range to compute Sa,avg. More work is needed to assess also "sufficiency" and "scaling robustness" desirable properties, which are disregarded in this dissertation. However, for ordinary records (i.e., with no pulse like effects), using the improved IMs is found to be more accurate than using the elastic- and inelastic-based IMs. For structural demands that are dominated by the first mode of vibration, using Sa,avg can be negligible relative to the conventionally-used Sa (T(¹)) and the advanced Sdi. For structural demands with sign.cant higher-mode contribution, an improved scalar IM that incorporates higher modes needs to be utilized. In order to fully understand the influence of the IM on the seismis risk, a simplified closed-form expression for the probability of exceeding a limit state capacity was chosen as a reliability measure under seismic excitations and implemented for Reinforced Concrete (RC) frame structures. This closed-form expression is partuclarly useful for seismic assessment and design of structures, taking into account the uncertainty in the generic variables, structural "demand" and "capacity" as well as the uncertainty in seismic excitations. The assumed framework employs nonlinear Incremental Dynamic Analysis (IDA) procedures in order to estimate variability in the response of the structure (demand) to seismic excitations, conditioned to IM. The estimation of the seismic risk using the simplified closed-form expression is affected by IM, because the final seismic risk is not constant, but with the same order of magnitude. Possible reasons concern the non-linear model assumed, or the insufficiency of the selected IM. Since it is impossibile to state what is the "real" probability of exceeding a limit state looking the total risk, the only way is represented by the optimization of the desirable properties of an IM.

A variable reactant transducer to study the oscillations of a pendulum and the value of local gravity

[EN]We describe a method for studying the classicalexperiment of the simple pendulum, consisting of a body of magnetic material oscillating through a thin conducting coil (magnetic pendulum), which according to Faraday’s law of induction generates a fluctuating current in the coil that can be transferred into a periodic signal in an oscilloscope. The set up described here allows to study the motion of the pendulum beyond what is normally considered in more basic settings, including a detailed analysis of both small and large oscillations, and the determination of the value of the acceleration of gravity.

Sviluppo e validazione di un modello di film fluido per simulazioni CFD di motori a combustione interna

A wall film model has been implemented in a customized version of KIVA code developed at University of Bologna. Under the hypothesis of `thin laminar ow' the model simulates the dynamics of a liquid wall film generated by impinging sprays. Particular care has been taken in numerical implementation of the model. The major phenomena taken into account in the present model are: wall film formation by impinging spray; body forces, such as gravity or acceleration of the wall; shear stress at the interface with the gas and no slip condition on the wall; momentum contribution and dynamic pressure generated by the tangential and normal component of the impinging drops; film evaporation by heat exchange with wall and surrounding gas. The model doesn't consider the effect of the wavy film motion and suppose that all the impinging droplets adhere to the film. The governing equations have been integrated in space by using a finite volume approach with a first order upwind differencing scheme and they have been integrated in time with a fully explicit method. The model is validated using two different test cases reproducing PFI gasoline and DI Diesel engine wall film conditions.

Application of FTIR microscopy to cultural heritage materials

Research in art conservation has been developed from the early 1950s, giving a significant contribution to the conservation-restoration of cultural heritage artefacts. In fact, only through a profound knowledge about the nature and conditions of constituent materials, suitable decisions on the conservation and restoration measures can thus be adopted and preservation practices enhanced. The study of ancient artworks is particularly challenging as they can be considered as heterogeneous and multilayered systems where numerous interactions between the different components as well as degradation and ageing phenomena take place. However, difficulties to physically separate the different layers due to their thickness (1-200 µm) can result in the inaccurate attribution of the identified compounds to a specific layer. Therefore, details can only be analysed when the sample preparation method leaves the layer structure intact, as for example the preparation of embedding cross sections in synthetic resins. Hence, spatially resolved analytical techniques are required not only to exactly characterize the nature of the compounds but also to obtain precise chemical and physical information about ongoing changes. This thesis focuses on the application of FTIR microspectroscopic techniques for cultural heritage materials. The first section is aimed at introducing the use of FTIR microscopy in conservation science with a particular attention to the sampling criteria and sample preparation methods. The second section is aimed at evaluating and validating the use of different FTIR microscopic analytical methods applied to the study of different art conservation issues which may be encountered dealing with cultural heritage artefacts: the characterisation of the artistic execution technique (chapter II-1), the studies on degradation phenomena (chapter II-2) and finally the evaluation of protective treatments (chapter II-3). The third and last section is divided into three chapters which underline recent developments in FTIR spectroscopy for the characterisation of paint cross sections and in particular thin organic layers: a newly developed preparation method with embedding systems in infrared transparent salts (chapter III-1), the new opportunities offered by macro-ATR imaging spectroscopy (chapter III-2) and the possibilities achieved with the different FTIR microspectroscopic techniques nowadays available (chapter III-3). In chapter II-1, FTIR microspectroscopy as molecular analysis, is presented in an integrated approach with other analytical techniques. The proposed sequence is optimized in function of the limited quantity of sample available and this methodology permits to identify the painting materials and characterise the adopted execution technique and state of conservation. Chapter II-2 describes the characterisation of the degradation products with FTIR microscopy since the investigation on the ageing processes encountered in old artefacts represents one of the most important issues in conservation research. Metal carboxylates resulting from the interaction between pigments and binding media are characterized using synthesised metal palmitates and their production is detected on copper-, zinc-, manganese- and lead- (associated with lead carbonate) based pigments dispersed either in oil or egg tempera. Moreover, significant effects seem to be obtained with iron and cobalt (acceleration of the triglycerides hydrolysis). For the first time on sienna and umber paints, manganese carboxylates are also observed. Finally in chapter II-3, FTIR microscopy is combined with further elemental analyses to characterise and estimate the performances and stability of newly developed treatments, which should better fit conservation-restoration problems. In the second part, in chapter III-1, an innovative embedding system in potassium bromide is reported focusing on the characterisation and localisation of organic substances in cross sections. Not only the identification but also the distribution of proteinaceous, lipidic or resinaceous materials, are evidenced directly on different paint cross sections, especially in thin layers of the order of 10 µm. Chapter III-2 describes the use of a conventional diamond ATR accessory coupled with a focal plane array to obtain chemical images of multi-layered paint cross sections. A rapid and simple identification of the different compounds is achieved without the use of any infrared microscope objectives. Finally, the latest FTIR techniques available are highlighted in chapter III-3 in a comparative study for the characterisation of paint cross sections. Results in terms of spatial resolution, data quality and chemical information obtained are presented and in particular, a new FTIR microscope equipped with a linear array detector, which permits reducing the spatial resolution limit to approximately 5 µm, provides very promising results and may represent a good alternative to either mapping or imaging systems.

Language and Embodiment: sensory-motor and linguistic-social experience. Evidence on sentence comprehension

In this work I address the study of language comprehension in an “embodied” framework. Firstly I show behavioral evidence supporting the idea that language modulates the motor system in a specific way, both at a proximal level (sensibility to the effectors) and at the distal level (sensibility to the goal of the action in which the single motor acts are inserted). I will present two studies in which the method is basically the same: we manipulated the linguistic stimuli (the kind of sentence: hand action vs. foot action vs. mouth action) and the effector by which participants had to respond (hand vs. foot vs. mouth; dominant hand vs. non-dominant hand). Response times analyses showed a specific modulation depending on the kind of sentence: participants were facilitated in the task execution (sentence sensibility judgment) when the effector they had to use to respond was the same to which the sentences referred. Namely, during language comprehension a pre-activation of the motor system seems to take place. This activation is analogous (even if less intense) to the one detectable when we practically execute the action described by the sentence. Beyond this effector specific modulation, we also found an effect of the goal suggested by the sentence. That is, the hand effector was pre-activated not only by hand-action-related sentences, but also by sentences describing mouth actions, consistently with the fact that to execute an action on an object with the mouth we firstly have to bring it to the mouth with the hand. After reviewing the evidence on simulation specificity directly referring to the body (for instance, the kind of the effector activated by the language), I focus on the specific properties of the object to which the words refer, particularly on the weight. In this case the hypothesis to test was if both lifting movement perception and lifting movement execution are modulated by language comprehension. We used behavioral and kinematics methods, and we manipulated the linguistic stimuli (the kind of sentence: the lifting of heavy objects vs. the lifting of light objects). To study the movement perception we measured the correlations between the weight of the objects lifted by an actor (heavy objects vs. light objects) and the esteems provided by the participants. To study the movement execution we measured kinematics parameters variance (velocity, acceleration, time to the first peak of velocity) during the actual lifting of objects (heavy objects vs. light objects). Both kinds of measures revealed that language had a specific effect on the motor system, both at a perceptive and at a motoric level. Finally, I address the issue of the abstract words. Different studies in the “embodied” framework tried to explain the meaning of abstract words The limit of these works is that they account only for subsets of phenomena, so results are difficult to generalize. We tried to circumvent this problem by contrasting transitive verbs (abstract and concrete) and nouns (abstract and concrete) in different combinations. The behavioral study was conducted both with German and Italian participants, as the two languages are syntactically different. We found that response times were faster for both the compatible pairs (concrete verb + concrete noun; abstract verb + abstract noun) than for the mixed ones. Interestingly, for the mixed combinations analyses showed a modulation due to the specific language (German vs. Italian): when the concrete word precedes the abstract one responses were faster, regardless of the word grammatical class. Results are discussed in the framework of current views on abstract words. They highlight the important role of developmental and social aspects of language use, and confirm theories assigning a crucial role to both sensorimotor and linguistic experience for abstract words.

Vibration as a method for muscular stimulation

Human reactions to vibration have been extensively investigated in the past. Vibration, as well as whole-body vibration (WBV), has been commonly considered as an occupational hazard for its detrimental effects on human condition and comfort. Although long term exposure to vibrations may produce undesirable side-effects, a great part of the literature is dedicated to the positive effects of WBV when used as method for muscular stimulation and as an exercise intervention. Whole body vibration training (WBVT) aims to mechanically activate muscles by eliciting neuromuscular activity (muscle reflexes) via the use of vibrations delivered to the whole body. The most mentioned mechanism to explain the neuromuscular outcomes of vibration is the elicited neuromuscular activation. Local tendon vibrations induce activity of the muscle spindle Ia fibers, mediated by monosynaptic and polysynaptic pathways: a reflex muscle contraction known as the Tonic Vibration Reflex (TVR) arises in response to such vibratory stimulus. In WBVT mechanical vibrations, in a range from 10 to 80 Hz and peak to peak displacements from 1 to 10 mm, are usually transmitted to the patient body by the use of oscillating platforms. Vibrations are then transferred from the platform to a specific muscle group through the subject body. To customize WBV treatments, surface electromyography (SEMG) signals are often used to reveal the best stimulation frequency for each subject. Use of SEMG concise parameters, such as root mean square values of the recordings, is also a common practice; frequently a preliminary session can take place in order to discover the more appropriate stimulation frequency. Soft tissues act as wobbling masses vibrating in a damped manner in response to mechanical excitation; Muscle Tuning hypothesis suggest that neuromuscular system works to damp the soft tissue oscillation that occurs in response to vibrations; muscles alters their activity to dampen the vibrations, preventing any resonance phenomenon. Muscle response to vibration is however a complex phenomenon as it depends on different parameters, like muscle-tension, muscle or segment-stiffness, amplitude and frequency of the mechanical vibration. Additionally, while in the TVR study the applied vibratory stimulus and the muscle conditions are completely characterised (a known vibration source is applied directly to a stretched/shortened muscle or tendon), in WBV study only the stimulus applied to a distal part of the body is known. Moreover, mechanical response changes in relation to the posture. The transmissibility of vibratory stimulus along the body segment strongly depends on the position held by the subject. The aim of this work was the investigation on the effects that the use of vibrations, in particular the effects of whole body vibrations, may have on muscular activity. A new approach to discover the more appropriate stimulus frequency, by the use of accelerometers, was also explored. Different subjects, not affected by any known neurological or musculoskeletal disorders, were voluntarily involved in the study and gave their informed, written consent to participate. The device used to deliver vibration to the subjects was a vibrating platform. Vibrations impressed by the platform were exclusively vertical; platform displacement was sinusoidal with an intensity (peak-to-peak displacement) set to 1.2 mm and with a frequency ranging from 10 to 80 Hz. All the subjects familiarized with the device and the proper positioning. Two different posture were explored in this study: position 1 - hack squat; position 2 - subject standing on toes with heels raised. SEMG signals from the Rectus Femoris (RF), Vastus Lateralis (VL) and Vastus medialis (VM) were recorded. SEMG signals were amplified using a multi-channel, isolated biomedical signal amplifier The gain was set to 1000 V/V and a band pass filter (-3dB frequency 10 - 500 Hz) was applied; no notch filters were used to suppress line interference. Tiny and lightweight (less than 10 g) three-axial MEMS accelerometers (Freescale semiconductors) were used to measure accelerations of onto patient’s skin, at EMG electrodes level. Accelerations signals provided information related to individuals’ RF, Biceps Femoris (BF) and Gastrocnemius Lateralis (GL) muscle belly oscillation; they were pre-processed in order to exclude influence of gravity. As demonstrated by our results, vibrations generate peculiar, not negligible motion artifact on skin electrodes. Artifact amplitude is generally unpredictable; it appeared in all the quadriceps muscles analysed, but in different amounts. Artifact harmonics extend throughout the EMG spectrum, making classic high-pass filters ineffective; however, their contribution was easy to filter out from the raw EMG signal with a series of sharp notch filters centred at the vibration frequency and its superior harmonics (1.5 Hz wide). However, use of these simple filters prevents the revelation of EMG power potential variation in the mentioned filtered bands. Moreover our experience suggests that the possibility of reducing motion artefact, by using particular electrodes and by accurately preparing the subject’s skin, is not easily viable; even though some small improvements were obtained, it was not possible to substantially decrease the artifact. Anyway, getting rid of those artifacts lead to some true EMG signal loss. Nevertheless, our preliminary results suggest that the use of notch filters at vibration frequency and its harmonics is suitable for motion artifacts filtering. In RF SEMG recordings during vibratory stimulation only a little EMG power increment should be contained in the mentioned filtered bands due to synchronous electromyographic activity of the muscle. Moreover, it is better to remove the artifact that, in our experience, was found to be more than 40% of the total signal power. In summary, many variables have to be taken into account: in addition to amplitude, frequency and duration of vibration treatment, other fundamental variables were found to be subject anatomy, individual physiological condition and subject’s positioning on the platform. Studies on WBV treatments that include surface EMG analysis to asses muscular activity during vibratory stimulation should take into account the presence of motion artifacts. Appropriate filtering of artifacts, to reveal the actual effect on muscle contraction elicited by vibration stimulus, is mandatory. However as a result of our preliminary study, a simple multi-band notch filtering may help to reduce randomness of the results. Muscle tuning hypothesis seemed to be confirmed. Our results suggested that the effects of WBV are linked to the actual muscle motion (displacement). The greater was the muscle belly displacement the higher was found the muscle activity. The maximum muscle activity has been found in correspondence with the local mechanical resonance, suggesting a more effective stimulation at the specific system resonance frequency. Holding the hypothesis that muscle activation is proportional to muscle displacement, treatment optimization could be obtained by simply monitoring local acceleration (resonance). However, our study revealed some short term effects of vibratory stimulus; prolonged studies should be assembled in order to consider the long term effectiveness of these results. Since local stimulus depends on the kinematic chain involved, WBV muscle stimulation has to take into account the transmissibility of the stimulus along the body segment in order to ensure that vibratory stimulation effectively reaches the target muscle. Combination of local resonance and muscle response should also be further investigated to prevent hazards to individuals undergoing WBV treatments.

Diagnostic techniques for EHD and MHD interaction

The impact of plasma technologies is growing both in the academic and in the industrial fields. Nowadays, a great interest is focused in plasma applications in aeronautics and astronautics domains. Plasma actuators based on the Magneto-Hydro-Dynamic (MHD) and Electro- Hydro-Dynamic (EHD) interactions are potentially able to suitably modify the fluid-dynamics characteristics around a flying body without utilizing moving parts. This could lead to the control of an aircraft with negligible response time, more reliability and improvements of the performance. In order to study the aforementioned interactions, a series of experiments and a wide number of diagnostic techniques have been utilized. The EHD interaction, realized by means of a Dielectric Barrier Discharge (DBD) actuator, and its impact on the boundary layer have been evaluated by means of two different experiments. In the first one a three phase multi-electrode flat panel actuator is used. Different external flow velocities (from 1 to 20m/s) and different values of the supplied voltage and frequency have been considered. Moreover a change of the phase sequence has been done to verify the influence of the electric field existing between successive phases. Measurements of the induced speed had shown the effect of the supply voltage and the frequency, and the phase order in the momentum transfer phenomenon. Gains in velocity, inside the boundary layer, of about 5m/s have been obtained. Spectroscopic measurements allowed to determine the rotational and the vibrational temperature of the plasma which lie in the range of 320 ÷ 440°K and of 3000 ÷ 3900°K respectively. A deviation from thermodynamic equilibrium had been found. The second EHD experiment is realized on a single electrode pair DBD actuator driven by nano-pulses superimposed to a DC or an AC bias. This new supply system separates the plasma formation mechanism from the acceleration action on the fluid, leading to an higher degree of the control of the process. Both the voltage and the frequency of the nano-pulses and the amplitude and the waveform of the bias have been varied during the experiment. Plasma jets and vortex behavior had been observed by means of fast Schlieren imaging. This allowed a deeper understanding of the EHD interaction process. A velocity increase in the boundary layer of about 2m/s had been measured. Thrust measurements have been performed by means of a scales and compared with experimental data reported in the literature. For similar voltage amplitudes thrust larger than those of the literature, had been observed. Surface charge measurements led to realize a modified DBD actuator able to obtain similar performances when compared with that of other experiments. However in this case a DC bias replacing the AC bias had been used. MHD interaction experiments had been carried out in a hypersonic wind tunnel in argon with a flow of Mach 6. Before the MHD experiments a thermal, fluid-dynamic and plasma characterization of the hypersonic argon plasma flow have been done. The electron temperature and the electron number density had been determined by means of emission spectroscopy and microwave absorption measurements. A deviation from thermodynamic equilibrium had been observed. The electron number density showed to be frozen at the stagnation region condition in the expansion through the nozzle. MHD experiments have been performed using two axial symmetric test bodies. Similar magnetic configurations were used. Permanent magnets inserted into the test body allowed to generate inside the plasma azimuthal currents around the conical shape of the body. These Faraday currents are responsible of the MHD body force which acts against the flow. The MHD interaction process has been observed by means of fast imaging, pressure and electrical measurements. Images showed bright rings due to the Faraday currents heating and exciting the plasma particles. Pressure measurements showed increases of the pressure in the regions where the MHD interaction is large. The pressure is 10 to 15% larger than when the MHD interaction process is silent. Finally by means of electrostatic probes mounted flush on the test body lateral surface Hall fields of about 500V/m had been measured. These results have been used for the validation of a numerical MHD code.

Scienza, Tecnica, Politica: Il Problema del Metodo nel Pensiero di Jacopo Aconcio

The aim of this PhD thesis is to study accurately and in depth the figure and the literary production of the intellectual Jacopo Aconcio. This minor author of the 16th century has long been considered a sort of “enigmatic character”, a profile which results from the work of those who, for many centuries, have left his writing to its fate: a story of constant re-readings and equally incessant oversights. This is why it is necessary to re-read Aconcio’s production in its entirety and to devote to it a monographic study. Previous scholars’ interpretations will obviously be considered, but at the same time an effort will be made to go beyond them through the analysis of both published and manuscript sources, in the attempt to attain a deeper understanding of the figure of this man, who was a Christian, a military and hydraulic engineer and a political philosopher,. The title of the thesis was chosen to emphasise how, throughout the three years of the doctorate, my research concentrated in equal measure and with the same degree of importance on all the reflections and activities of Jacopo Aconcio. My object, in fact, was to establish how and to what extent the methodological thinking of the intellectual found application in, and at the same time guided, his theoretical and practical production. I did not mention in the title the author’s religious thinking, which has always been considered by everyone the most original and interesting element of his production, because religion, from the Reformation onwards, was primarily a political question and thus it was treated by almost all the authors involved in the Protestant movement - Aconcio in the first place. Even the remarks concerning the private, intimate sphere of faith have therefore been analysed in this light: only by acknowledging the centrality of the “problem of politics” in Aconcio’s theories, in fact, is it possible to interpret them correctly. This approach proves the truth of the theoretical premise to my research, that is to say the unity and orderliness of the author’s thought: in every field of knowledge, Aconcio applies the rules of the methodus resolutiva, as a means to achieve knowledge and elaborate models of pacific cohabitation in society. Aconcio’s continuous references to method can make his writing pedant and rather complex, but at the same time they allow for a consistent and valid analysis of different disciplines. I have not considered the fact that most of his reflections appear to our eyes as strongly conditioned by the time in which he lived as a limit. To see in him, as some have done, the forerunner of Descartes’ methodological discourse or, conversely, to judge his religious theories as not very modern, is to force the thought of an author who was first and foremost a Christian man of his own time. Aconcio repeats this himself several times in his writings: he wants to provide individuals with the necessary tools to reach a full-fledged scientific knowledge in the various fields, and also to enable them to seek truth incessantly in the religious domain, which is the duty of every human being. The will to find rules, instruments, effective solutions characterizes the whole of the author’s corpus: Aconcio feels he must look for truth in all the arts, aware as he is that anything can become science as long as it is analysed with method. Nevertheless, he remains a man of his own time, a Christian convinced of the existence of God, creator and governor of the world, to whom people must account for their own actions. To neglect this fact in order to construct a “character”, a generic forerunner, but not participant, of whatever philosophical current, is a dangerous and sidetracking operation. In this study, I have highlighted how Aconcio’s arguments only reveal their full meaning when read in the context in which they were born, without depriving them of their originality but also without charging them with meanings they do not possess. Through a historical-doctrinal approach, I have tried to analyse the complex web of theories and events which constitute the substratum of Aconcio’s reflection, in order to trace the correct relations between texts and contexts. The thesis is therefore organised in six chapters, dedicated respectively to Aconcio’s biography, to the methodological question, to the author’s engineering activity, to his historical knowledge and to his religious thinking, followed by a last section concerning his fortune throughout the centuries. The above-mentioned complexity is determined by the special historical moment in which the author lived. On the one hand, thanks to the new union between science and technique, the 16th century produces discoveries and inventions which make available a previously unthinkable number of notions and lead to a “revolution” in the way of studying and teaching the different subjects, which, by producing a new form of intellectual, involved in politics but also aware of scientific-technological issues, will contribute to the subsequent birth of modern science. On the other, the 16th century is ravaged by religious conflicts, which shatter the unity of the Christian world and generate theological-political disputes which will inform the history of European states for many decades. My aim is to show how Aconcio’s multifarious activity is the conscious fruit of this historical and religious situation, as well as the attempt of an answer to the request of a new kind of engagement on the intellectual’s behalf. Plunged in the discussions around methodus, employed in the most important European courts, involved in the abrupt acceleration of technical-scientific activities, and especially concerned by the radical religious reformation brought on by the Protestant movement, Jacopo Aconcio reflects this complex conjunction in his writings, without lacking in order and consistency, differently from what many scholars assume. The object of this work, therefore, is to highlight the unity of the author’s thought, in which science, technique, faith and politics are woven into a combination which, although it may appear illogical and confused, is actually tidy and methodical, and therefore in agreement with Aconcio’s own intentions and with the specific characters of European culture in the Renaissance. This theory is confirmed by the reading of the Ars muniendorum oppidorum, Aconcio’s only work which had been up till now unavailable. I am persuaded that only a methodical reading of Aconcio’s works, without forgetting nor glorifying any single one, respects the author’s will. From De methodo (1558) onwards, all his writings are summae, guides for the reader who wishes to approach the study of the various disciplines. Undoubtedly, Satan’s Stratagems (1565) is something more, not only because of its length, but because it deals with the author’s main interest: the celebration of doubt and debate as bases on which to build religious tolerance, which is the best method for pacific cohabitation in society. This, however, does not justify the total centrality which the Stratagems have enjoyed for centuries, at the expense of a proper understanding of the author’s will to offer examples of methodological rigour in all sciences. Maybe it is precisely because of the reforming power of Aconcio’s thought that, albeit often forgotten throughout the centuries, he has never ceased to reappear and continues to draw attention, both as a man and as an author. His ideas never stop stimulating the reader’s curiosity and this may ultimately be the best demonstration of their worth, independently from the historical moment in which they come back to the surface.