1,721,025 research outputs found
Digital Mammography: physical priciples and future applications
No full textMammography is currently considered the best tool for the detection of breast cancer, pathology with a rate of incidence in constant increase. To produce the radiological picture a screen film combination is conventionally used. One of the inherent limitations of screen- film combination is the fact that the detection, display and storage processes are one and the same, making it impossible to separately optimize each stage. These limitations can be overcome with digital systems. In this work we evaluate the main characteristics of digital detectors available on the market and we compare the performance of digital and conventional systems. Digital mammography, due to the possibility to process images, offers many potential advantages, among these the possibility to introduce the dual-energy technique which employs the composition of two digital images obtained with two different energies to enhance the inherent contrast of pathologies by removing the uniform background. This technique ..
Application of the K-edge X-ray technique to map pigments of art paintings: Preliminary results
No full textThe synapsins: key actors of synapse function and plasticity
No full textThe synapsins are a family of neuronal phosphoproteins evolutionarily conserved in invertebrate and vertebrate organisms. Their best-characterised function is to modulate neurotransmitter release at the presynaptic terminal, by reversibly tethering synaptic vesicles (SVs) to the actin cytoskeleton. However, many recent data have suggested novel functions for synapsins in other aspects of the presynaptic physiology, such as SV docking, fusion and recycling. Synapsin activity is tightly regulated by several protein kinases and phosphatases, which modulate the association of synapsins to SVs as well as their interaction with actin filaments and other synaptic proteins. In this context, synapsins act as a link between extracellular stimuli and the intracellular signalling events activated upon neuronal stimulation. Genetic manipulation of synapsins in various in vivo models has revealed that, although not essential for the basic development and functioning of neuronal networks, these proteins are extremely important in the fine-tuning of neuronal plasticity, as shown by the epileptic phenotype and behavioural abnormalities characterising mouse lines lacking one or more synapsin isoforms.
In this review, we summarise the current knowledge about how the various members of the synapsin family are involved in the modulation of the presynaptic physiology. We give a comprehensive description of the molecular basis of synapsin function, as well as an overview of the more recent evidence linking mutations in the synapsin proteins to the onset of severe central nervous system diseases such as epilepsy and schizophrenia
Homeostatic Plasticity in Epilepsy
Full text linkIn the healthy brain, neuronal excitability and synaptic strength are homeostatically regulated to keep neuronal network activity within physiological boundaries. Epilepsy is characterized by episodes of highly synchronized firing across in widespread neuronal populations, due to a failure in regulation of network activity. Here we consider epilepsy as a failure of homeostatic plasticity or as a maladaptive response to perturbations in the activity. How homeostatic compensation is involved in epileptogenic processes or in the chronic phase of epilepsy, is still debated. Although several theories have been proposed, there is relatively little experimental evidence to evaluate them. In this perspective, we will discuss recent results that shed light on the potential role of homeostatic plasticity in epilepsy. First, we will present some recent insights on how homeostatic compensations are probably active before and during epileptogenesis and how their actions are temporally regulated and closely dependent on the progression of pathology. Then, we will consider the dual role of transcriptional regulation during epileptogenesis, and finally, we will underline the importance of homeostatic plasticity in the context of therapeutic interventions for epilepsy. While classic pharmacological interventions may be counteracted by the epileptic brain to maintain its potentially dysfunctional set point, novel therapeutic approaches may provide the neuronal network with the tools necessary to restore its physiological balance
Il gioco delle grandi potenze. La competizione nel Mediterraneo allargato
No full textLe grandi potenze sono tornate a competere per la più importante delle poste in gioco possibili: la ridefinizione dell’ordine internazionale. Una partita in cui ogni mossa contribuisce ad alterare gli equilibri internazionali. Chi ne uscirà vincitore? Per rispondere occorre riflettere su quell’intreccio di interessi e rapporti di potere che caratterizza le relazioni internazionali contemporanee e che trova nel Mediterraneo allargato uno dei suoi scacchieri principali. Il libro prende in esame alcuni dei Paesi più influenti dell’area – dall’Arabia Saudita all’Iran, da Israele alla Turchia – e altrettanti dossier di sicurezza – dall’eredità delle primavere arabe, alla penetrazione russa e cinese in Nordafrica e Sahel, passando per le incertezze in materia di immigrazione e politiche energetiche – nel tentativo di comprendere le sfide di oggi e gli scenari di domani
La valvulopatia mitro-aortica. Trattamento chirurgico mediante commissuroplastica mitralica e sostituzione aortica
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