3,325 research outputs found
Higher-dimensional Clifford-Severi equalities
No full textLet X be a smooth complex projective variety, a: X → A a morphism to an abelian variety such that pic0(A) injects into pic0(X) and let L be a line bundle on X; denote by ha0(X,L) the minimum of h0(X,LS - a-α) for α Pic0(A). The so-called Clifford-Severi inequalities have been proven in [M. A. Barja, Generalized Clifford-Severi inequality and the volume of irregular varieties, Duke Math. J. 164(3) (2015) 541-568; M. A. Barja, R. Pardini and L. Stoppino, Linear systems on irregular varieties, J. Inst. Math. Jussieu (2019) 1-39; doi:10.1017/S1474748019000069]; in particular, for any L there is a lower bound for the volume given by: vol(L) ≥ n!ha0(X,L), and, if KX - L is pseudoeffective, vol(L) ≥ 2n!ha0(X,L). In this paper, we characterize varieties and line bundles for which the above Clifford-Severi inequalities are equalities
Severi varieties
No full text8 pagesR. Hartshorne conjectured and F. Zak proved that any n-dimensional smooth non-degenerate complex algebraic variety X in a m-dimensional projective space P satisfies Sec(X)=P if m<3n/2+2. In this article, I deal with the limiting case of this theorem, namely the Severi varieties, defined by the conditions m=3n/2+2 and Sec(X) different from P. I want to give a different proof of a theorem of F. Zak classifying all Severi varieties: I will prove that any Severi variety is homogeneous and then deduce their classification and the following geometric property : the derivatives of the equation of Sec(X), which is a cubic hypersurface, determine a birational morphism of P
Sviluppo e validazione di procedure innovative per l'aumento osseo peri-implantare
No full textLa deiscenza peri-implantare (BD) è l’esposizione, sull’aspetto vestibolare dell’impianto, della superficie ruvida di un impianto. Le BD sono una evenienza comune quando impianti di diametro standard vengono posizionati in regioni anatomiche della cavità orale come le regioni posteriori mascellari e mandibolari. Inoltre, una BD può formarsi durante la fase iniziale di guarigione di un impianto come conseguenza del riassorbimento verticale e orizzontale del piatto osseo vestibolare peri-implantare (PBBP) dopo il posizionamento implantare.
La presenza di una BD residua dopo una procedura ricostruttiva è stata associata elevata incidenza di mucosite peri-implantare e peri-implantite (Schwarz et al. 2012). Inoltre, quando veniva indotta una peri-implantite, la sua progressione era più rapida rispetto a quella indotta su impianti circondati da osso (Monje et al. 2019).
Di conseguenza, lo scopo di questa tesi di Dottorato è stato valutare l’efficacia di una nuova tecnica di gestione dei tessuti molli (la Sub-periosteal Peri-implant Augmented Layer, SPAL; Trombelli et al. 2018), rispondendo alle seguenti domande:
1. Qual è l’efficacia della SPAL, contestuale al posizionamento implantare, nel prevenire o correggere una BD?
2. Esistono differenze nelle condizioni dei tessuti peri-implantari a breve termine in pazienti trattati con SPAL rispetto a pazienti che presentavano un PBBP spesso (≥ 2 mm) al posizionamento implantare?
3. E’ possible effettuare un aumento osseo su siti con BD combinando la tecnica SPAL e un blocco di osso bovino (bDBBM)?
4. Qual è l’efficacia della SPAL nel trattamento di difetti ossei causati dalla peri-implantite?
Sono stati condotti i seguenti studi:
I.TROMBELLI L, SEVERI M, PRAMSTRALLER M, FARINA R (2019) A simplified soft tissue management for peri-implant bone augmentation. The International Journal of Oral and Maxillofacial Implants 34, 197–204.
II. TROMBELLI L, PRAMSTRALLER M, SEVERI M, SIMONELLI A, FARINA R (2020a)
Peri-implant tissue conditions at implants treated with Sub-periosteal Peri-implant Augmented Layer technique: A retrospective case series. Clinical Oral Implant Research 31, 992-1001.
III. TROMBELLI L, SEVERI M, ORTENSI L, FARINA R (2021) Peri-implant bone augmentation by the sub-periosteal peri-implant augmented layer technique and a bovine-derived bone block: A case report Clinical Advance in Periodontics, ahead of print, doi: 10.1002/cap.10172
IV. TROMBELLI L, SEVERI M, FARINA R, SIMONELLI A (2020b) Sub-periosteal peri-implant augmented layer technique to treat peri-implantitis lesions Clinical Advance in Periodontics, 0, 1-6
Sulla base della presente evidenza possono essere tratte le seguenti conclusioni:
1. La tecnica SPAL rappresenta un valido approccio chirurgico semplificato associato a un basso livello di complicanze nel trattamento della BD e nell’aumento orizzontale dei tessuti peri-implantari.
2. Dopo 6 mesi di carico protesico, i pazienti trattati con SPAL mostrano una infiammazione mucosa limitata associata a una ridotta profondità di sondaggio e quantità adeguata di mucosa cheratinizzata. Negli impianti trattati con SPAL, tuttavia, il livello osseo radiografico interprossimale è risultato apicale rispetto alla sua posizione ideale.
3. La combinazione di SPAL e bDBBM può essere usata con successo per ottenere un incremento nello spessore del tessuto vestibolare nella porzione più coronale di un impianto esposto.
4. La tecnica SPAL con o senza CTG può risultare in una remissione clinical di difetti legati alla peri-implantite di Classe Ib/Ic technique with or without additional CTG. Quanto questi effetti possano essere mantenuti a lungo termine ed estesi a difetti di differente configurazione deve ancora essere valutato.The purpose of this Ph.D. thesis was to evaluate the effectiveness of a novel surgical soft tissue management (the Sub-periosteal Peri-implant Augmented Layer, SPAL; Trombelli et al. 2018) by addressing the following questions:
1. What is the clinical effectiveness of SPAL technique in the preventing or correcting a peri-implant bone dehiscence or at implant placement?
2. Is there any difference in peri-implant tissue conditions on the short-term at patients receiving SPAL technique compared to patients with adequate thickness (≥ 2 mm) of PBBP at implant placement?
3. May bone augmentation be performed successfully at peri-implant dehiscence sites with a combination of SPAL and a deproteinized bovine bone mineral (DBBM) block?
4. What is the clinical effectiveness of SPAL technique in the regenerative treatment of peri-implantitis bone defects?
On the basis of the produced evidence, the following conclusions can be drawn:
1. SPAL technique represents a valuable simplified approach in the prevention or correction of peri-implant bone dehiscence
2. After 6 months of prosthetic loading, patients treated with SPAL technique show limited peri-implant mucosal inflammation in association with shallow PD and adequate KM. At implants receiving SPAL technique, however, interproximal RBL was found apical to its ideal position.
3. The combination of SPAL and bDBBM may be successfully used to achieve an increase in buccal tissue thickness at the most coronal portion of an exposed implant.
4. SPAL technique with or without additional CTG may result in the clinical remission of Class Ib/Ic peri-implantitis defects. Whether and to what extent these beneficial effects may be maintained long-term needs be carefully assessed
Cambios en los hábitos alimentarios y actividad física durante el aislamiento físico durante el COVID -19: estudio descriptivo sobre una muestra de trabajadores (Uruguay, abril 2020)
No full textC. Severi: Departamento de Medicina Preventiva y Social, Facultad de Medicina, Universidad de la República.--
M. Medina, Facultad de Medicina, Universidad de la República. Doctoranda de la Universidad de Granada.--Antecedentes: La aparición en Uruguay del coronavirus, hizo que el gobierno declarara emergencia sanitaria Entre otras medidas sugirió a la población evitar en forma voluntaria, la circulación fuera de su casa. Esto trajo algunas consecuencias en el cambio de hábitos alimentarios y la actividad física.Objetivo: Identificar los cambios en el comportamiento respecto a la alimentación y la actividad física en la emergencia sanitaria, en los trabajadores donde se implementó trabajo a distancia.Metodología: Se aplicó una encuesta telefónica sobre una muestra por conveniencia de 170 trabajadores de una empresa sobre sus hábitos alimentarios y actividad física. Resultados: La tercera parte de los trabajadores (30,6 %) perciben incremento de peso, y cambiaron su comportamiento, casi el 47 % manifiesta que come más o con mayor frecuencia. Respecto al tipo de alimentos la mayor parte refiere que incrementaron alimentos ricos en carbohidratos y ultra procesados. En un porcentaje alto la población redujo su actividad física. En gran parte de los hogares conviven niños, lo que genera un ambiente obesogénico, que incrementa el riego de exceso de peso a corto y mediano plazo. Conclusión: Existen cambios de comportamiento alimentario y de actividad física no saludables y que promueven el riego de enfermedades crónicas no transmisibles. Se sugiere tomar medidas que acompañen las ya realizadas para contener la transmisión del coronavirus en la comunidad
Cell-specific dynamic clamp analysis of the role of funny If current in cardiac pacemaking
No full textWe used the Dynamic Clamp technique for i) comparative validation of conflicting computational models of the hyperpolarization-activated funny current, If, and ii) quantification of the role of If in mediating autonomic modulation of heart rate. Experimental protocols based on the injection of a real-time recalculated synthetic If current in sinoatrial rabbit cells were developed. Preliminary results of experiments mimicking the autonomic modulation of If demonstrated the need for a customization procedure to compensate for cellular heterogeneity. For this reason, we used a cell-specific approach, scaling the maximal conductance of the injected current based on the cell's spontaneous firing rate. The pacemaking rate, which was significantly reduced after application of Ivabradine, was restored by the injection of synthetic current based on the Severi-DiFrancesco formulation, while the injection of synthetic current based on the Maltsev-Lakatta formulation did not produce any significant variation. A positive virtual shift of the If activation curve, mimicking the Isoprenaline effects, led to a significant increase in pacemaking rate (+17.3 ± 6.7%, p < 0.01), although of lower magnitude than that induced by real Isoprenaline (+45.0 ± 26.1%). Similarly, a negative virtual shift of the activation curve significantly lowered the pacemaking rate (-11.8 ± 1.9%, p < 0.001), as did the application of real Acetylcholine (-20.5 ± 5.1%). The Dynamic Clamp approach, applied to the If study in cardiomyocytes for the first time and rate-adapted to manage intercellular variability, indicated that: i) the quantitative description of the If current in the Severi-DiFrancesco model accurately reproduces the effects of the real current on rabbit sinoatrial cell pacemaking rate and ii) a significant portion (50-60%) of the physiological autonomic rate modulation is due to the shift of the If activation curve
Rate-adapted dynamic-clamp of the funny current in sinoatrial pacemaker cells
No full textA typical feature of sinoatrial node (SAN) pacemaker cells is the presence of an ionic current, named 'funny current', If, that activates upon hyperpolarization. We aimed to: 1) test the impact of different mathematical models of If (Maltsev-Lakatta and Severi-DiFrancesco) in real cells by using the Dynamic Clamp (DC) technique; 2) adapt the DC protocol to adequately simulate a shift of the If activation curve. Two different protocols were implemented: i) the If was selectively blocked by Ivabradine and substituted with a "synthetic" If dynamically reconstructed from the experimentally recorded action potentials of a single isolated rabbit SAN cell according to the mathematical models; ii) virtual negative shift of the If activation curve by the injection of a compensatory current using DC. The Severi-DiFrancesco model allowed the restoration of control pacemaking rate while the MaltsevLakatta model did not. The compensatory current used to reproduce the negative shift of the activation curve did not yield the expected results; we therefore adapted the Dynamic Clamp to the single-cell specific behavior by scaling the estimated If current based on the spontaneous firing rate. This adaptation protocol succeeded in reproducing the effects of a negative activation shift. The Ivabradine protocol was then repeated with this adjustment and the results were fully consistent with those previously obtained
Evolution of the Seminal O'Hara Rudy Model to More Accurately Simulate the Electrophysiology of Human Ventricular Cardiomyocytes
No full textThe aim of our work consists in developing a new model of the human ventricular cardiomyocyte, based on the O'Hara-Rudy model (ORd), to improve, in particular, the action potential duration (APD) dependence on the extracellular Ca2+ concentration (Cao). Moreover, the new model reproduces all the available experimental data on APD rate dependence, APD restitution, drug block effects, etc., when the experimental extracellular ionic concentrations are carefully reproduced in simulationsThe main differences between our and the ORd model are: a novel Markovian formulation for the L-type Ca2+ current; the Markovian rapid delayed rectifier K+ current formulation published by Li et al.; a new formulation of the Ca2+ release from the sarcoplasmic reticulum. Several model parameters were modifiedOur BS (Bartolucci-Severi) model successfully improved the ORd, one of the most detailed, used and influent models in computational cardiology, by reproducing the APD-Cao relationship while keeping all the original model features tested in the appropriate experimentally-matched conditions. Furthermore, the BS was suitability as baseline for the generation of in silico populations of models and for reproducing cardiac abnormalities such as early afterdepolarizations
M. Houseman & C. Severi, Naven ou Le donner à voir. Essai d'interprétation de l'action rituelle
No full textMonnerie Denis. M. Houseman & C. Severi, Naven ou Le donner à voir. Essai d'interprétation de l'action rituelle. In: L'Homme, 1998, tome 38 n°148. Lignage, mariage, héritage. pp. 268-270
Arthur Symons Translator of Gabriele D'Annunzio's Plays
No full textThe article analyzes Symons rythmic translations of D'Annunzio's plays, their performances and literary reception and adds a list of all of D'Annunzio's works in English as well as holograph letters of the author and his English translator
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