67,632 research outputs found
Conclusions: Late Chalcolithic Northern Mesopotamia. Setting the Agenda in the Debate on the Rise of Urbanization in the Ancient Near East
No full text(not requested
Evoluzione morfologica della Sciara del Fuoco (Isola di Stromboli) durante l’eruzione del 2002-2003 mediante l’utilizzo della fotogrammetria digitale multi-temporale
No full textDopo un periodo di attività anomala del vulcano Stromboli (Arcipelago delle Isole Eolie, figura 1), il 30 dicembre 2002 il versante nord-est dell’Isola, in corrispondenza alla depressione della “Sciara del Fuoco”, è stato interessato da una frana di grandi proporzioni, che ha coinvolto anche la parte sottomarina dell’edificio vulcanico. La frana, provocando il distacco di alcune decine di milioni di metri cubi di materiale, ha innescato uno tsunami con onde di altezza di diversi metri che hanno danneggiato edifici ed imbarcazioni nei villaggi di Stromboli e Ginostra. Negli ultimi anni, progetti di ricerca finanziati dal Gruppo Nazionale per la Vulcanologia (GNV) sono stati dedicati alla ricostruzione dettagliata della morfologia sub-aerea e sottomarina del vulcano con lo scopo di individuare e studiare i fenomeni di instabilità provocati principalmente dall’attività eruttiva. L’eruzione del 2002-2003, verificandosi prima della fine dei progetti, è stata analizzata a partire dai dati acquisiti nel biennio 2001-2002. L’attività effusiva, iniziata il 28 dicembre 2002, si è conclusa in luglio 2003 rimodellando il pendio attraverso processi di erosione e accumulo di lava. Durante la crisi l’attività di monitoraggio, coordinata dal Dipartimento della Protezione Civile, si è basata su diverse metodologie, tra le quali la fotogrammetria digitale (Kraus, 1998), utili alla valutazione dei fenomeni di instabilità in corso (Baldi et al., 2000; Baldi et al., 2002; Mora et al., 2003). L’attività di fotogrammetria digitale, coordinata dal gruppo di ricerca del progetto n.13 finanziato dal GNV (Programma Quadro 1999-2001), ha reso possibile la ricostruzione dettagliata della morfologia sub-aerea della Sciara del Fuoco, con lo scopo di individuare e studiare i fenomeni di instabilità provocati principalmente dall’attività eruttiva. Il confronto tra i dati ottenuti prima dell’eruzione e quelli acquisiti il 5 gennaio 2003, assieme ad un rilievo batimetrico, hanno consentito di definire la geometria e di stimare i volumi coinvolti dalle frane.
I successivi 13 rilievi fotogrammetrici (da gennaio a settembre 2003, tabella 1), effettuati dall’Aeronautica Militare e dalla società Nuova Avioriprese, hanno permesso il monitoraggio continuo delle variazioni morfologiche indotte dall’effusione lavica e dall’evoluzione dei fenomeni di instabilità. I modelli digitali del terreno ottenuti, sono stati utilizzati per estrarre mappe morfologiche dettagliate (estremamente importanti in zone di difficile o impossibile accesso come in aree vulcaniche), per determinare e mappare i cambiamenti successivi, per quantificare le deformazioni, per localizzare le bocche eruttive e per individuare e classificare i siti potenzialmente soggetti a rischio di croll
Forced vibrations of a nonhomogeneous string
No full textWe prove existence of vibrations of a nonhomogeneous string under a nonlinear time periodic forcing term in the case in which the forcing frequency avoids resonances with the vibration modes of the string (nonresonant case). The proof relies on a Lyapunov–Schmidt reduction and a Nash–Moser iteration scheme
Ernia di Richter: a case report. Considerazioni clinico-terapeutiche.
No full text[Richter's hernia: a clinical case and the clinico-therapeutic considerations]. Fornaro R, Terrizzi A, Davini MD, Canaletti M, Baldi E, Bonfante P, Sticchi C, Cavaliere D, Ferraris R.
The authors report a case of Richter's hernia. They underline main clinical and therapeutic patterns, emphasizing the need of an early diagnosis and surgery. This is a hernia of abdominal wall with partial entrapment of bowel wall (antimesenteric site) through a small ring. The incidence increased in the last years because of diffusion of laparoscopic techniques. Richter's hernia could be asymptomatic for a long time or show vanish sign. Sometimes this hernia can be diagnosed during surgery. The clinical signs are conclamated if hernia is complicated by strangulation. High mortality is justified by performing too late diagnosis and operation
L’emangiopericitoma renale. Considerazioni anatomo patologiche e clinico-terapeutiche. Descrizione di un caso.
No full text[Renal hemangiopericytoma. Anatomo-pathologic and clinico-therapeutic considerations. A case report]. G Chir. 1999 Jan-Feb;20(1-2):20-4. Fornaro R, Terrizzi A, Secco GB, Canaletti M, Baldi E, Bonfante P, Sticchi C, Baccini P, Cittadini G Jr, Fiorini G, Ferraris R. Cattedra di Semeiotica Chirurgica I, Università degli Studi di Genova. The Authors report a case of renal hemangiopericytoma, whose interest is related to the extreme rarity (24 cases reported until today), its insidious growth, the late in diagnosis, its uncertain clinical-biological evolution, not always predictable. Considering chemotherapy and radiotherapy ineffectiveness, an adequate treatment for such a neoplasm requires the surgical therapy, which must
be followed by a careful follow-up
The high resolution topographic model of Panarea Island (Italy)
No full textAerial digital photogrammetry, aerial laser scanning and multibeam bathymetry, play a fundamental role in the generation of Digital Terrrain Models (DTM) of subaerial and submarine areas. Integrating these survey techniques is crucial for providing accurate and homogeneous digital terrain models along narrow coastal zones that often cannot be adequately surveyed due to logistical limitations of collecting bathymetric data in shallow water. In this poster, three aerial photogrammetric surveys, two multibeam bathymetric surveys and a LIDAR survey are analyzed and integrated together to generate the first 3D high resolution DTMM (Digital Terrain and Marine Model) of the volcanic island of Panarea (Aeolian islands, Italy). This is an active area that underwent a submarine gas eruption on November 2002, and produced impacts on the environment and potential hazards for the local population. Our DTMM shows the morphological features of this volcanic area at an average grid size resolution of 1 m and a maximum elevation error of 1 m. Here we show and discuss our integrated DTMM co-registered in the same reference system. This DTMM will significantly improve geophysical and geomorphological studies of this active volcanic island for reducing hazar
A note on KAM theory for quasi-linear and fully nonlinear forced KdV
No full textWe present recent results concerning quasi-periodic solutions for quasilinear and fully nonlinear forced perturbations of KdV equations. For Hamiltonian or reversible nonlinearities the solutions are linearly stable. The proofs are based on a combination of different
ideas and techniques: (i) a Nash-Moser iterative scheme in Sobolev scales. (ii) A regularization procedure, which conjugates the linearized operator to a differential operator with constant coefficients
plus a bounded remainder. These transformations are obtained by changes of variables induced by diffeomorphisms of the torus and pseudo-differential operators. (iii) A reducibility KAM scheme,
which completes the reduction to constant coefficients of the linearized operator, providing a sharp asymptotic expansion of the perturbed eigenvalues
KAM for autonomous quasi-linear perturbations of KdV
No full textWe prove the existence and the stability of Cantor families of quasi-periodic, small amplitude solutions of quasi-linear (i.e. strongly nonlinear) autonomous Hamiltonian differentiable perturbations of KdV. This is the first result that extends KAM theory to quasi-linear autonomous and parameter independent PDEs. The core of the proof is to find an approximate inverse of the linearized operators at each approximate solution and to prove that it satisfies tame estimates in Sobolev spaces. A symplectic decoupling procedure reduces the problem to the one of inverting the linearized operator restricted to the normal directions. For this aim we use pseudo-differential operator techniques to transform such linear PDE into an equation with constant coefficients up to smoothing remainders. Then a linear KAM reducibility technique completely diagonalizes such operator. We introduce the “initial conditions” as parameters by performing a “weak” Birkhoff normal form analysis, which is well adapted for quasi-linear perturbations
KAM for quasi-linear and fully nonlinear forced perturbations of Airy equation
No full textWe prove the existence of small amplitude quasi-periodic solutions for quasi-linear and fully nonlinear forced perturbations of the linear Airy equation. For Hamiltonian or reversible nonlinearities we also prove their linear stability. The key analysis concerns the reducibility of the inearized operator at an approximate solution, which provides a sharp asymptotic expansion of its eigenvalues. For quasi-linear perturbations this cannot be directly obtained by a KAM iteration. Hence we first perform a regularization procedure, which conjugates the linearized operator to an operator with constant coefficients plus a bounded remainder. These transformations are obtained by changes of variables induced by diffeomorphisms of the torus and pseudo-differential operators. At this point we implement a Nash-Moser iteration (with second order Melnikov non-resonance conditions) which completes the reduction to constant coefficients
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