1,721,495 research outputs found
Post-orogenic extension in southern Tuscany: distinct extensional episodes or progressive exhumation?
No full textA detailed structural analysis of the Pseudoverrucano Unit at Punta delle Rocchette, southwestern Tuscany, Italy, reveals a complex kinematic evolution for well-ex- posed marly limestones and shales of the the Punta delle Rocchette Fm. of Middle Liassic age. These rocks, defor- med under very-low metamorphic conditions, are affected by W-verging, asymmetrical chevron folds that were first recognized in the '60s. The folds are characterized by horizontal to moderately ESE-dipping axial surfaces and sub-horizontal, NNE trending axes. These structures are intimately associated to W-dipping, low-angle normal faults cutting across the Punta delle Rocchette Fm. and small stepped faults cutting across the fold reverse limbs. The latter are mainly isolated, but occasionally they are linked to form extensional duplex structures with an overall top-to-the- west sense of shear. Low-angle normal faults trend parallel to fold axes, and are cut by a set of high-angle normal faults. Both normal fault sets are parallel in trend and dip, and are kinematically consistent to all previously de- scribed structures. The NNE trending high-angle normal faults separate the Punta delle Rocchette Fm. from the conformably underlying Upper Triassic Clastic basal Fm. (Pseudoverrucano s.s.) to the east, and from Upper Oligo- cene Macigno costiero Fm. and other terrains of the un- metamorphosed Falda Toscana Unit, to the west. Because of the close geometric and kinematic consistency between folds, low-angle and high-angle normal faults, it seems reasonable that folding of the Punta delle Rocchette Fm. was due to vertical shortening (i.e. flattening) accompanied by top-to-the-west shear. Detailed examination of the deformation fabrics associated with each recognised class of structures reveals that folding was dominantly ductile, whereas low-angle and high-angle normal faults were developed under brittle-ductile and brittle deformation conditions, respectively. Folds and normal faults postdate the development of top-to-the east duplexes hence an episode of horizontal shortening
West-directed deformations within the Pseudoverrucano Unit, SW Tuscany, Italy: An example of extensional folding? [Pieghe con vergenza occidentale nell'Unità dello Pseudoverrucano, Toscana meridionale: un esempio di deformazione distensiva?]
No full textComunemente le pieghe sono interpretate come il ri- sultato di deformazioni caratterizzate da raccorciamenti orizzontali tipiche di regimi compressivi. Tuttavia, duran- te gli ultimi decenni sono stati descritti diversi esempi di pieghe sviluppate in regimi estensionali caratterizzati invece da raccorciamenti verticali ed estensione orizzontale. I primi esempi di piegamento collegato a estensione orizzontale riportati in letteratura sono rappresentati da pieghe aperte con piano assiale sub-verticale sviluppate in seguito all’attività di faglie listriche come pieghe di tipo roll-over oppure al piegamento per riequilibrio isostatico del letto di faglie a basso angolo di importanza regionale. Altri esempi di pieghe sviluppate a seguito di estensione orizzontale con profilo da chiuso a isoclinale e accompagnate dallo sviluppo di una foliazione di piano assiale sub-orizzontale sono state per lo più descritte all’interno di zone milonitiche nel let- to di importanti faglie a basso angolo od in rocce appartenenti a livelli strutturali profondi. Più rari sono invece gli esempi di pieghe caratterizzate da piano assiale sub-orizzontale, descritte all’interno di rocce non metamorfiche o affette da metamorfismo di basso e bassissimo grado in livelli strut- turali poco profondi; strutture di questo tipo sono state interpretate come pieghe sviluppate a seguito di deformazioni estensionali. Tra questi alcuni esempi notevoli sono stati segnalati in rocce non metamorfiche e di basso grado metamorfico dell’Appennino toscano.
L’analisi strutturale di dettaglio dell’Unità dello Pseudoverrucano, affiorante in località Punta delle Rocchette (Toscana meridionale), ha messo in evidenza un’evoluzione cinematica complessa della Formazione calcareo-marnosa di Punta delle Rocchette di età Liassica. Queste rocce, interessate da metamorfismo di basso grado, sono deformate da pieghe di tipo chevron asimmetriche con vergenza occidentale già riconosciute. Le pieghe sono caratterizzate da superfici assiali orizzontali o solo debolmente inclinate verso ESE e assi sub-orizzontali con direzione media NNE.Commonly, folds are interpreted as crustal shortening-related structures. However, in the past few decades, many examples of extension-related folds have been described. The earliest examples of folding during horizontal extension are represented by upright open folds associated to listric normal fault activity such as roll-over folds or buoyancy-related folding of detachment footwalls (HARRIS et alii, 2002 and references therein). Examples of extension-related folds showing close geometry and accompanied by subhorizontal axial planar foliation have been mainly described from mylonite zones along extensional detachments or within deep structural levels of collapsed orogens (DIRKS et alii, 1997; HARRIS et alii, 2002). Only few examples of folds characterized by subhorizontal axial plane and found in low-grade metamorphic rocks have been interpreted as extension-related structures (FROITZHEIM, 1992; BURG et alii, 1996; OROZCO et alii, 1998). Amongst the latter, remarkable cases have been described in both unmetamorphosed and low-grade metamorphic terrains of the Tuscan Apennines (CARMIGNANI et alii, 1993; ELTER & SANDRELLI, 1994; CAMPETTI et alii, 1999; LIOTTA, 2002). A detailed structural analysis of the Pseudoverrucano Unit at Punta delle Rocchette (fig. 1), southwestern Tuscany, Italy, reveals a complex kinematic evolution for well-exposed marly limestones and shales of the Punta delle Rocchette Fm. of Middle Liassic age (DECANDIA & LAZZAROTTO, 1980 and references therein). These rocks, deformed under very-low metamorphic conditions (LEONI et alii, 1993), are affected by W-verging, asymmetrical chevron folds that were first recognized by FAZZINI & PAREA (1966). The folds are characterized by horizontal to moderately ESE-dipping axial surfaces and sub-horizontal, NNE trending axes. These structures are intimately associated to W-dipping, low-angle normal faults cutting across the Punta delle Rocchette Fm. and small stepped faults cutting across the fold reverse limbs. The latter are mainly isolated, but occasionally they are linked to form extensional duplex structures with an overall top-to-the-west sense of shear (fig. 2). Low-angle normal faults trend parallel to fold axes, and are cut by a set of highangle normal faults. Both normal fault sets are parallel in trend and dip, and are kinematically consistent to all previously described structures. The NNE trending high-angle normal faults separate the Punta delle Rocchette Fm. from the conformably underlying Upper Triassic Clastic basal Fm. (Pseudoverrucano s.s.) to the east, and from Upper Oligocene Macigno costiero Fm. and other terrains of the unmetamorphosed Falda Toscana Unit, to the west (fig. 3). Because of the close geometric and kinematic consistency between folds, low-angle and high-angle normal faults, it seems reasonable that folding of the Punta delle Rocchette Fm. was due to vertical shortening (i.e. flattening) accompanied by top-to-the-west shear. Detailed examination of the deformation fabrics associated with each recognised class of structures reveals that folding was dominantly ductile, whereas low-angle and high-angle normal faults were developed under brittle-ductile and brittle deformation conditions, respectively. Folds, low-angle and high-angle normal faults may thus represent the effects of distinct episodes, or probably of distinct stages of a single episode of W-directed extension. The extensional folds described at Punta delle Rocchette may just be a manifestation of local deformations; however, the geometrical consistency of these structures with other fold systems reported from scattered outcrops of western Tuscany indicate that they are probably related to processes of regional, rather than local, tectonic importance. Irrespective of the driving force that was responsible for the development of these extensional deformations (syn-collisional back-sliding, late/post-collisional extension etc), the folds described in this study represent a further example of asymmetric extension-related folding of very low-grade metamorphic rocks
Programmi di riqualificazione urbana
No full textIl capitolo analizza le problematiche normative e giurisprudenziali connesse all'introduzione dei programmi di riqualificazione urban
Hydroxylation of 5H-3-oxo-2,3,6,7,8,9-hexahydro-imidazo-[1,2-a]-azepine derivatives by molecular oxygen
No full textBilateral noncalcified astrocytic hamartomas in retinitis pigmentosa: Multimodal imaging evaluation over 8 years of follow-up
No full textPurpose: To report the evolution of optic disk noncalcified astrocytic hamartomas in a patient with retinitis pigmentosa throughout 8 years of follow-up. Methods: Case report. Results: A 42-year-old white man with a diagnosis of retinitis pigmentosa was referred to our medical retinal center for the first time in 2010, for the development of a new optic nerve head lesion in the right eye. Fundus examination, fundus autofluorescence, fluorescein and green indocyanine angiography, spectral-domain optical coherence tomography were performed and confirmed the presence of a papillary noncalcified astrocytic hamartoma in the right eye. Four years later, multimodal imaging evaluation revealed in the left eye the presence of a first optic disk benign tumor, and in 2018, a second in the nasal retina, while in the right eye the sole papillary lesion increased slightly in size. Conclusions: Noncalcified astrocytic hamartomas can occur in patients with retinitis pigmentosa and can increase in size and number in time. A complete multimodal imaging evaluation is necessary to identify and classify any kind of new lesion that, as known, are associated with these group of hereditary retinal degenerations
Evidence for a double vergence in the Northern Apennines, Italy: Observations from the Arenarie di Poggio al Carpino Fm., Southern Tuscany, Italy [Evidenze di doppia vergenza nell'Appennino Settentrionale: osservazioni dalla Formazione delle Arenarie di Poggio al Carpino, Toscana Meridionale, Italia]
No full textL’analisi delle strutture mesoscopiche che caratteriz- zano la Formazione delle Arenarie di Poggio al Carpino (Permo-Triass) appartenente al Complesso Metamorfico Toscano, in località «I Canaloni» (Toscana meridionale), ha messo in evidenza la sovrapposizione di due fasi defor- mative principali a vergenza opposta. La prima fase è caratterizzata da trasporto tettonico top-to-the WSW. A questa fase è legato lo sviluppo di una foliazione attualmente preservata nei livelli più compe- tenti della Formazione. La seconda fase mostra senso di taglio top-to-the ENE ed è rappresentata da vene di estensione, pieghe asimmetriche, sovrascorrimenti con geometrie flat-ramp-flat e duplex.
Le strutture della prima fase sono probabilmente collegate alle fasi Cretaceo-Paleogeniche alpine, caratterizzate in generale da condizioni di HP-LT, e potrebbero essersi sviluppate in seguito ad un processo precoce di subduzione con polarità orientale. Rocce metamorfiche di HP-LT sono attualmente esposte in altri settori dell’Appennino settentrionale (metaofioliti del Monte Argentario e rocce a Mg-carfolite).In locality «I Canaloni» (Southern Tuscany), the analysis of mesoscopic structures within the Arenarie di Poggio al Carpino sandstones Fm. (Permian-Triassic), belonging to the Tuscan Metamorphic Complex, highlighted the occurrence of two main deformational episodes with opposite sense of shear. The first episode is characterized by top-to-the WSW sense of shear and it is responsible for the development of a foliation preserved within the stiff layers of the Formation. The second episode shows top-to-the ENE shear sense and it is represented by extensional veins, asymmetric folds, thrusts showing flat-ramp-flat geometries and duplexes. The structures of the first deformational episode probably developed during Cretaceous-Paleogene alpine phases, generally characterised by HF-LT metamorphic conditions, and they may represent the evidence of an initial east-dipping subduction process. HP-LT metamorphic rocks are exposed in other locations along the inner zones of the Northern Apennines (Argentario Mt. meta-ophiolite and Mg-carpholite-bearing rocks)
Structure Activity Relationships of the Ficin Hydrolysis of X-Phenyl Hippurates. Comparison with Papain, Actinidin and Bromelain
No full text
Effects of high energy phosphates and L-arginine on the ion membrane conductance and excitability characteristics of ischemic and reperfused rat skeletal muscle fibers
No full textIn skeletal muscle, 4 h of ischemia followed by 30 min of reperfusion depolarizes the fibers, markedly increases the Cl- and glibenclamide-sensitive K+ conductances and reduces the excitability of the fibers. The ischemia-reperfusion also significantly decreases the ATP content of the muscles. In the present work, the electrical parameters of reperfused extensor digitorum longus muscle of rats were measured in vitro at 30 degrees C, by a computerized two-intracellular microelectrode technique, before and after in vivo pretreatment with equimolar doses of phosphocreatine disodium salt tetrahydrate, phosphocreatine di-L-arginine salt and L-arginine hydrochloride. In the same experimental situations the ATP content of the muscles was also measured. Both phosphocreatine salts prevented the increase of membrane ion conductance due to muscle reperfusion by preloading the muscle fibers with extra ATP. Phosphocreatine disodium salt also prevented the depolarization and restored the normal excitability of the reperfused fibers. In contrast, phosphocreatine di-L-arginine salt did not restore the resting potential nor the excitability of the fibers, but it decreased the amplitude of the action potential by reducing the overshoot. The pretreatment with L-arginine also failed to protect the electrical parameters of the fibers from the ischemic-reperfusion insult. Furthermore, the L-amino acid produced a more pronounced reduction of the excitability of the fibers by increasing the threshold current needed to elicit an action potential and reducing it overshoot. The in vitro application of L-arginine to the muscle also reduced the overshoot of the action potential, suggesting a direct interaction of the L-amino acid with Na+ channels
Radioactivity effects of Pb-17Li in fusion power reactors
No full textResearch on the eutectic Pb17Li is part of the blanket studies carried out in Europe for fusion power reactors. The use of this breeder makes easier some safety problems as compared to the case of lithium as a consequence of the lower chemical reactivity of Pb17Li. On the other hand, it increases the radioactivity problems due to the neutron activation of lead and impurities. This paper presents both short-term (accidents) and long-term (waste disposal and recycling) aspects of the Pb17Li activation products. They include the production, mobilization, release and environmental impact. Concerning accidents, a particular attention is given to Po-210 and Hg-203. Questions related to waste management are also revised. The most attractive solution seems that of recycling the spent Pb17Li. This will be possible about 20 y after removal from service. As an alternative to recycling, the breeder disposal as radioactive waste is discussed
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