74 research outputs found
Sistemi di trasmissione ibridi per applicazioni off-highway: le macchine elettriche, la loro alimentazione e il loro controllo. Analisi dei vantaggi competitivi ottenibili attraverso schemi e soluzioni innovative
No full textHybridization and electrification of mobile working machinery are becoming promising areas of research and development for the off-highway industry. In this context, numerical modeling plays a fundamental role in predicting the performance of the vehicle transmission system and in optimizing its operation. A good design of the mechanical and electrical components of a hybrid transmission can be achieved only through an integrated approach.
Regarding the hybrid electric traction, by means of the Ph.D. with high level training apprenticeship contract, I proceeded to the identification and analysis of some schemes in order to develop innovative solutions for the off-highway industry.
I dealt with innovative solutions focusing on the modeling of industrial hybrid electric transmissions and agricultural electric powersplit transmissions. I chose to use AMESim as 1D multi-domain dynamic simulation tool. The results showed that an industrial vehicle equipped with an electric-hydrodynamic hybrid transmission, demonstrates 8% lower fuel consumption than a conventional vehicle. A representative working cycle defined by the author on the basis of the company experience and the data collected in literature was proposed as basis for comparison. Within the agricultural transmissions the electric variator has proved to be more competitive even better than conventional hydrostatic variator for power-split applications.
I went into detail about the design of electrical machines and their related power and control technologies adopted for off-highway hybrid transmission considering also their integration into the mechanical system. This activity, aimed at the design of an electric drive for an industrial application, has allowed me to develop a model of electric motor, taking into account iron and copper losses, to be integrated in the simulation model of the complete vehicle. In this way, the electromagnetic and thermal design aspects were examined, identifying the parameters of optimization and the trade-offs that play a role in the design of a permanent magnet synchronous electric machine and in the development of the control algorithms.
Having identified and quantified the benefits of hybrid solutions compared to conventional designs, thanks to the skills that I have acquired during the training period inside the company, my research has focused on the development of a preliminary design for a hybrid transmission, addressing also constructive aspects: from mechanical design to manufacturing and assembly. This concept will be tested in the research and development department of the company upon completion of the detailed design
The kinetics of the IPSC, the heterogeneity and the noise affect the firing coherence of a population of inhibitory interneurons
No full textThe Fast Spiking interneurons are coupled by both inhibitory and electrical synapses and the experimental findings suggest they operate as clockworks affecting the neural information processing. At present, the functional role of the electrical synapses in a network of inhibitory interneurons is not well understood. In this paper, this issue is investigated by using a single compartment biophysical interneuron model of a Fast Spiking cell. In particular, the parameter values leading to the emergence of synchronous regimes in a network model of inhibitory interneurons coupled by chemical and electrical synapses are determined theoretically in the weak-coupling limit. Moreover, the effects on the firing coherence, arising from heterogeneity and noise, are studied by means of numerical simulations, both for a pair of Fast Spiking cells and for larger size networks
Sleep-wake cycle: a new analysis for the two-step process model
No full textIl ciclo sonno-veglia é oggetto di studio per molti scienziati e matematici da più di trent’anni ma nonostante ciò molti quesiti non trovano ancora una risposta. Capire i meccanismi e le dinamiche del ciclo sonno-veglia è un problema molto importante perché le sue alterazioni possono avere conseguenze significative sulla salute umana.
In questo lavoro viene presentato un modello matematico, con basi biologiche, del ciclo sonno-veglia. La principale novità rispetto ai modelli precedenti è l’utilizzo di un accurato modello neuronale, il modello di Hodgkin-Huxley, che permette di descrivere il sistema usando connessioni sinaptiche realistiche.
Crediamo fermamente che questo argomento meriti una investigazione dettagliata, non solo per il contenuto fisico e matematico, ma anche per il suo potenziale impatto sulla ricerca nel campo della sanità
Modelli biofisici di interneuroni e fenomeni di sincronizzazione
No full textIn questa tesi vengono studiate le proprietà di sincronizzazione di una rete di interneuroni FS accoppiati da sinapsi inibitorie ed elettriche. Lo studio si basa su un nuovo modello biofisico per la singola cellula, costituito da un sistema non lineare di equazioni differenziali, che descrive la dinamica del potenziale di membrana e la cinetica delle variabili di gating legate alla conduttanza della membrana cellulare. Il modello utilizzato è stato costruito partendo dai dati sperimentali sugli interneuroni FS presenti in letteratura, in modo da riprodurre quanto più accuratamente possibile le loro principali caratteristiche elettrofisiologiche
Environmental enrichment strengthens corticocortical interactions and reduces amyloid-β oligomers in aged mice
No full textBrain aging is characterized by global changes which are thought to underlie age-related cognitive decline. These include variations in brain activity and the progressive increase in the concentration of soluble amyloid-β (Aβ) oligomers, directly impairing synaptic function and plasticity even in the absence of any neurodegenerative disorder. Considering the high social impact of the decline in brain performance associated to aging, there is an urgent need to better understand how it can be prevented or contrasted. Lifestyle components, such as social interaction, motor exercise and cognitive activity, are thought to modulate brain physiology and its susceptibility to age-related pathologies. However, the precise functional and molecular factors that respond to environmental stimuli and might mediate their protective action again pathological aging still need to be clearly identified. To address this issue, we exploited environmental enrichment (EE), a reliable model for studying the effect of experience on the brain based on the enhancement of cognitive, social and motor experience, in aged wild-type mice. We analyzed the functional consequences of EE on aged brain physiology by performing in vivo local field potential (LFP) recordings with chronic implants. In addition, we also investigated changes induced by EE on molecular markers of neural plasticity and on the levels of soluble Aβ oligomers. We report that EE induced profound changes in the activity of the primary visual and auditory cortices and in their functional interaction. At the molecular level, EE enhanced plasticity by an upward shift of the cortical excitation/inhibition balance. In addition, EE reduced brain Aβ oligomers and increased synthesis of the Aβ-degrading enzyme neprilysin. Our findings strengthen the potential of EE procedures as a non-invasive paradigm for counteracting brain aging processes
Indium-111 Oxine platelets survival in patients suffering of cardiac and cerebral artheriosclerosis
No full textIndium-111 Oxine Platelets Survival In Patients Suffering Of Cardiac And Cerebral Arteriosclerosis
No full textEnvironmental enrichment modulates cortico-cortical interactions in the mouse
No full textEnvironmental enrichment (EE) is an experimental protocol based on a complex sensorimotor stimulation that dramatically affects brain development. While it is widely believed that the effects of EE result from the unique combination of different sensory and motor stimuli, it is not known whether and how cortico-cortical interactions are shaped by EE. Since the primary visual cortex (V1) is one of the best characterized targets of EE, we looked for direct cortico-cortical projections impinging on V1, and we identified a direct monosynaptic connection between motor cortex and V1 in the mouse brain. To measure the interactions between these areas under standard and EE rearing conditions, we used simultaneous recordings of local field potentials (LFPs) in awake, freely moving animals. LFP signals were analyzed by using different methods of linear and nonlinear analysis of time series (cross-correlation, mutual information, phase synchronization). We found that EE decreases the level of coupling between the electrical activities of the two cortical regions with respect to the control group. From a functional point of view, our results indicate, for the first time, that an enhanced sensorimotor experience impacts on the brain by affecting the functional crosstalk between different cortical areas
Dual inhibition of MAPK/ERK and BMP signaling induces entorhinal-like identity in mouse ESC-derived pallial progenitors
No full text: The mechanisms that determine distinct embryonic pallial identities remain elusive. The central role of Wnt signaling in directing dorsal telencephalic progenitors to the isocortex or hippocampus has been elucidated. Here, we show that timely inhibition of MAPK/ERK and BMP signaling in neuralized mouse embryonic stem cells (ESCs) specifies a cell identity characteristic of the allocortex. Comparison of the global gene expression profiles of neural cells generated by MAPK/ERK and BMP inhibition (MiBi cells) with those of cells from early postnatal encephalic regions reveals a pallial identity of MiBi cells, distinct from isocortical and hippocampal cells. MiBi cells display a unique pattern of gene expression and connectivity, and share molecular and electrophysiological features with the entorhinal cortex. Our results suggest that early changes in cell signaling can specify distinct pallial fates that are maintained by specific neuronal lineages independent of subsequent embryonic morphogenetic interactions and can determine their functional connectivity
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