1,064 research outputs found
Seismotomography of the crust in the transition zone between the southern Tyrrhenian and Sicilian tectonic domains
A crustal tomography of seismic wave velocity was performed in the contact zone between the southern Tyrrhenian, Sicilian and Ionian tectonic units, a zone where the lithospheric structure can be expected to furnish evident signatures of dynamics related to the Tyrrhenian subduction process. A dataset of 10241 P and 5597 S readings from 932 local earthquakes recorded between 1978 and 2001 by stations operating in Sicily and Calabria was inverted by the SIMULPS12 algorithm for simultaneous computation of hypocenter parameters and Vp and Vp/Vs three dimensional distributions. The study brought significant improvement in the knowledge of the local velocity structure, furnishing new information useful to better identify the local tectonic units. The results appear to be compatible with the most recent hypotheses regarding the geodynamics of the study region
Seismic strain and seismogenic stress regimes in the crust of the southern Tyrrhenian region
An investigation has been performed to identify and characterize the seismic deformation zones active over the last decades in the region of Italy that has experienced the strongest seismicity during the last centuries. The study is based on the estimate of hypocenter locations, fault plane solutions, seismogenic stress and seismic strain tensor orientations carried out using the entire dataset of the national and local seismic networks, and the recently improved three-dimensional (3D) crustal velocity model of the study area. A series of simulation tests have been performed to evaluate the significance of the earthquake space distribution obtained and whether it was influenced by network geometry problems related to the sea and the lack of ocean bottom seismometers. In the sectors where hypocentral location was synthetically proved to be reliable, space distributions of earthquakes located with epicenter and focal depth errors less than 3 and 4 km, respectively, have been compared with local geology in order to identify seismogenic faults. The dataset of 32 fault plane solutions estimated with fault parameter errors less than 20° has been used to investigate space variations of seismogenic stress and seismic strain orientations over the study area. Stress was found to be uniform in the Messina Strait and southern Calabria where inversion of the available set of 11 fault plane solutions showed clear evidence of an extensional regime. The different orientations of the minimum compressive stress and strain found in this sector, together with the information available on local geology and tectonics, lead us to propose that the seismicity occurring over the last decades in the Messina Strait and southern Calabria was not in general produced at the main faults, but at minor faults activated by the main tectonic stress field acting in the area. To the west, in the sector including western Etna, the Nebrodi chain and the western Aeolian Islands, analysis of the available set of 16 fault plane solutions revealed a certain degree of stress heterogeneity with an apparent prevalence of north–south compression. This east to west change of stress–strain regimes is evaluated in the light of current hypotheses regarding the geodynamics of the study region
Nucleation Induced Undulative Instability in Thin Films of nCB Liquid Crystals
A surface instability is reported in thin nematic films of 5CB and 8CB,
occurring near the nematic--isotropic phase transition.
Although this instability leads to patterns reminiscent of spinodal
dewetting, we show that it is actually based on a nucleation mechanism. Its
characteristic wavelength does not depend markedly on film thickness, but
strongly on the heating rate.Comment: 4 pages, 5 figure
Localizzazione probabilistica 3D (NonLinLoc) applicata all’area calabro-peloritana
Sono presentati e discussi i risultati
preliminari relativi ad una ri-localizzazione
probabilistica non-lineare 3D dei terremoti
dell’area compresa tra il Tirreno meridionale
e l’Arco Calabro-Peloritano (Italia
meridionale).
Scopo del lavoro è dimostrare che
l’applicazione di un’approccio probabilistico
non-lineare nella localizzazione dei terremoti
può fornire dei risultati più accurati ai fini
della sorveglianza, ovviando al problema
degli outlier, rispetto alle tecniche di
localizzazione lineari (e.g. Hypoellipse), che
minimizzano simultaneamente tutti i residui
tra fasi osservate e calcolate.
Il programma utilizzato è NonLinLoc
[Lomax, et al., 2000; Lomax, et al., 2001;
Lomax, 2005; http://www.alomax.net/nlloc;
NonLinLoc di seguito] il quale permette di
effettuare un’efficiente ricerca globale dello
spazio dei parametri ipocentrali (coordinate
spaziali e tempo origine) ottenendo una
stima della funzione densità di probabilitÃ
(pdf, probability density function) a
posteriori. La pdf fornisce una descrizione
completa della localizzazione e delle sue
incertezze; il campionamento dello spazio
dei parametri ipocentrali è stato fatto
mediante la tecnica Oct-tree nella regione
compresa tra 37.75 e 39.40 N in latitudine e
tra 14.80 e 16.80 E in longitudine, e
utilizzando tutti gli eventi con profondità H
≤30 km.
La struttura dell’Oct-tree è stata imposta in
100,000 celle ed un insieme di queste celle
viene poi salvata in modo da poter
rappresentare graficamente la pdf mediante
nubi di punti a diversa densità .
Il dataset utilizzato per le nostre analisi è
composto da 1,304 terremoti, di 1.0<M<4.3,
registrati nel periodo compreso tra il 1994 e
il 2006; il modello di velocità 3D adottato è
stato ottenuto da Barberi et al., 2008 [poster
presentato a questo convegno] invertendo lo stesso dataset, mediante l’utilizzo del
software TomoDD.
I risultati ottenuti sono stati confrontati sia
con le localizzazioni 1D (Hypoellipse) che
con quelle 3D. Si evidenzia una maggiore
clusterizzazione degli eventi e, soprattutto,
un evidente miglioramento della qualità delle
localizzazioni utilizzando il modello di
velocità crostale 3D. Per cui riteniamo che,
l’applicazione del metodo probabilistico
associato ad un buon modello di velocità 3D,
può essere utilizzato ai fini di sorveglianza
Seismic location improvements from an OBS/H temporary network in Southern Tyrrhenian Sea
We present the first investigation performed on the seismicity of Southern Tyrrhenian Sea, off-shore Sicily
with the contribution of data from broad-band ocean bottom seismometers and hydrophones (OBS/H). Offshore
data were recorded during the TYrrhenian Deep sea Experiment (TYDE) from December 2000 to May
2001 in the Southern Tyrrhenian Sea. Hypocenter locations of a cluster of 53 seismic events occurred in
March 2001 in north-eastern Sicily were estimated by the integration of land (permanent network) and offshore
(temporary network) data and compared with locations estimated from land data only. The scatter of
the cluster was evaluated by dispersion parameters. The off-shore data significantly reduced the scatter of
the swarm hypocenters also restricting the depth range of the cluster. Moreover, space trends of the event
distribution originally shown by the land data were only partially confirmed by the land-sea joint data.
In order to assess the efficiency in terms of hypocenter mislocations in the subject area, of a land-sea
integrated network with respect to a land-based network, we performed simulations by assuming a grid
distribution of earthquakes and a recent local 3D velocity model, computing synthetic arrival times of body
waves to the stations of both network configurations (integrated and land-based) perturbing the computed
times and relocating earthquakes by inversion. The results of the synthetic tests demonstrated that the
presence of sea bottom stations in the Tyrrhenian basin can reduce the mislocations of large magnitude
and/or superficial earthquakes in the southernmost Calabria and Messina Strait and of low magnitude and/or
deep earthquakes in north-eastern Sicily. The major accuracy of synthetic earthquake locations obtained
including OBS/H data provides an additional support to the interpretation of the cluster occurred in March
2001 and to the opportunity of long-term installation of an off-shore network like TYDE in the study region
Tectonics and seismicity of the Tindari Fault System, southern Italy: Crustal deformations at the transition between ongoing contractional and extensional domains located above the edge of a subducting slab
The Tindari Fault System (southern Tyrrhenian Sea, Italy) is a regional zone of brittle deformation located at the transition between ongoing contractional and extensional crustal compartments and lying above the western edge of a narrow subducting slab. Onshore structural data, an offshore seismic reflection profile, and earthquake data are analyzed to constrain the
present geometry of the Tindari Fault System and its tectonic evolution since Neogene, including the present seismicity. Results show that this zone of deformation consists of a broad NNW trending system of faults including sets of right-lateral, left-lateral, and extensional faults as well as early strike-slip faults
reworked under late extension. Earthquakes and other neotectonic data provide evidence that the Tindari Fault System is still active in the central and northern sectors and mostly accommodates extensional or rightlateral transtensional displacements on a diffuse array of faults. From these data, a multiphase tectonic history is inferred, including an early phase as a right-lateral strike-slip fault and a late extensional reworking under the influence of the subductionrelated processes, which have led to the formation of the Tyrrhenian back-arc basin. Within the present, regional, geodynamic context, the Tindari Fault System is interpreted as an ongoing accommodation zone between the adjacent contractional and extensional crustal compartments, these tectonic compartments relating to the complex processes of plate convergence occurring in the region. The Tindari
Fault System might also be included in an incipient, oblique-extensional, transfer zone linking the ongoing contractional belts in the Calabrian-Ionian and southern Tyrrhenian compartments
Variations of Procalcitonin Serum Levels in Neonatal Period
PCR and qPCR detection of HCV, HBV, Dengue, HIV, HSV, H5, CMV, M. tuberculosis, C. trachomatis and N. gonorrhoeae. This method has been being employed for all PCR diagnostic tests carried out at our laboratory, as well as at other diagnostic laboratories where our PCR diagnostic kits are being used. Conclusion: This method has a broad application potential since it can be used in diagnostic laboratories which are capable of doing PCR to detect human pathogens. Additionally, it can be helpful for developing the standard criteria for diagnostic PCR
Localizzazione probabilistica 3D (NonLinLoc) applicata all’area calabro-peloritana
Sono presentati e discussi i risultati
preliminari relativi ad una ri-localizzazione
probabilistica non-lineare 3D dei terremoti
dell’area compresa tra il Tirreno meridionale
e l’Arco Calabro-Peloritano (Italia
meridionale).
Scopo del lavoro è dimostrare che
l’applicazione di un’approccio probabilistico
non-lineare nella localizzazione dei terremoti
può fornire dei risultati più accurati ai fini
della sorveglianza, ovviando al problema
degli outlier, rispetto alle tecniche di
localizzazione lineari (e.g. Hypoellipse), che
minimizzano simultaneamente tutti i residui
tra fasi osservate e calcolate.
Il programma utilizzato è NonLinLoc
[Lomax, et al., 2000; Lomax, et al., 2001;
Lomax, 2005; http://www.alomax.net/nlloc;
NonLinLoc di seguito] il quale permette di
effettuare un’efficiente ricerca globale dello
spazio dei parametri ipocentrali (coordinate
spaziali e tempo origine) ottenendo una
stima della funzione densità di probabilitÃ
(pdf, probability density function) a
posteriori. La pdf fornisce una descrizione
completa della localizzazione e delle sue
incertezze; il campionamento dello spazio
dei parametri ipocentrali è stato fatto
mediante la tecnica Oct-tree nella regione
compresa tra 37.75 e 39.40 N in latitudine e
tra 14.80 e 16.80 E in longitudine, e
utilizzando tutti gli eventi con profondità H
≤30 km.
La struttura dell’Oct-tree è stata imposta in
100,000 celle ed un insieme di queste celle
viene poi salvata in modo da poter
rappresentare graficamente la pdf mediante
nubi di punti a diversa densità .
Il dataset utilizzato per le nostre analisi è
composto da 1,304 terremoti, di 1.0<M<4.3,
registrati nel periodo compreso tra il 1994 e
il 2006; il modello di velocità 3D adottato è
stato ottenuto da Barberi et al., 2008 [poster
presentato a questo convegno] invertendo lo stesso dataset, mediante l’utilizzo del
software TomoDD.
I risultati ottenuti sono stati confrontati sia
con le localizzazioni 1D (Hypoellipse) che
con quelle 3D. Si evidenzia una maggiore
clusterizzazione degli eventi e, soprattutto,
un evidente miglioramento della qualità delle
localizzazioni utilizzando il modello di
velocità crostale 3D. Per cui riteniamo che,
l’applicazione del metodo probabilistico
associato ad un buon modello di velocità 3D,
può essere utilizzato ai fini di sorveglianza
Wide band gap materials as a new tuning strategy for dye doped cholesteric liquid crystals laser
A new tuning strategy for mirror-less liquid crystals laser is presented. A three layer cell is prepared with two cholesteric layers sandwiching a layer containing an isotropic mixture of a photoluminescent dye. One of the chiral layers contains a wide band gap material while the second layer consists of a series of small band gap materials. Through the combination of these two layers, a set of mirrors that can selectively reflect different wavelengths is obtained. A different laser wavelength is emitted from different regions of the cell under the pumping beam irradiation. (C) 2009 Optical Society of Americ
- …