607 research outputs found
Core-mantle boundary deformations and J2 variations resulting from the 2004 Sumatra earthquake
The deformation at the core-mantle boundary produced by the 2004 Sumatra
earthquake is investigated by means of a semi-analytic theoretical model of
global coseismic and postseismic deformation, predicting a millimetric
coseismic perturbation over a large portion of the core-mantle boundary.
Spectral features of such deformations are analysed and discussed. The
time-dependent postseismic evolution of the elliptical part of the gravity
field (J2) is also computed for different asthenosphere viscosity models. Our
results show that, for asthenospheric viscosities smaller than 10^18 Pa s, the
postseismic J2 variation in the next years is expected to leave a detectable
signal in geodetic observations.Comment: 14 pages, 8 figures, 1 table. It will appear in Geophysical Journal
Internationa
Environmental magnetic records of mid-late Pleistocene drift sedimentary sequences from the Antarctic Peninsula, Pacific margin
The Pacific Continental Margin of the Antarctic Peninsula was the area of interest of the Sediment Drift of The Antarctic Offshore Project (SEDANO Project). A paleomagnetic and environmental study was carried out on four Pleistocene sequences from Drift 7. High resolution measurements were performed on u-channels and about forty-three discrete samples. This work focus on the definition of the mineralogy of the main magnetic carriers which is still matter of debate and on the study of the short time variability of magnetite grain-size which results particularly evident during the last glaciation. ARM/κ magnetic parameter resulted to be a good record of such variability and reflects changes in the sedimentation on the rise when the ice sheet was probably closer to the continental shelf edge. An integrated age model has been provided for cores SED-12 and -13, which have the higher sedimentation rates
Paleogene calcareous nannofossil biostratigraphic updates from equatorial Indian Ocean
Biostratigrafia e paleoceanografia di sedimenti provenienti dall'Oceano indiano equatorial
Anomalous last interglacial Tyrrhenian sea levels and Neanderthal settling at Guattari and Moscerini caves (central Italy)
We present a geological-stratigraphical study aimed to provide chronologic constraints to the sea-level markers occurring at two coastal caves of central Italy (Grotta Guattari and Grotta dei Moscerini) and to the Neanderthal frequentation of these caves, in the light of recent archaeological and geomorphological-geochronological studies suggesting similar sea levels during MIS 5.5 and MIS 5.3, and only few m below the Present during MIS 5.1 in this region. Based on the review of previous literature data, combined with new stratigraphic observations at Grotta Guattari and re-analysis of archive material including unpublished field notes from Grotta dei Moscerini, we reconstruct a plausible sea-level history accounting for the lithological and paleoenvironmental features of their sedimentary fillings. In particular, we outline the abundant occurrence of well-rounded pumice clasts within the sedimentary deposits of Moscerini Cave, attesting for the proximity to the beach where this pumice was gathered by wave action. Through the petrographic and geochemical analysis of this pumice we evidence provenance from Phlegraean Fields and Ischia Island volcanic districts, framing their chronology in the time span 118–40 ka, consistent with literature ESR-U/Th dates providing ages ranging 101 ± 5–74 ± 7 ka for the sedimentary filling of both Moscerini and Guattari caves
Environmental magnetic records of Mid-Late Pleistocene drift sedimentary sequences from the Antarctic Peninsula, Pacific Margin
The Pacific Continental Margin of the Antarctic Peninsula was the area of interest of the Sediment Drift of The Antarctic Offshore Project (SEDANO Project). A paleomagnetic and environmental study was carried out on four Pleistocene sequences from Drift 7. High resolution measurements were performed on u-channels and about forty-three discrete samples. This work focus on the definition of the mineralogy of the main magnetic carriers which is still matter of debate and on the study of the short time variability of magnetite grain-size which results particularly evident during the last glaciation. ARM/k magnetic parameter resulted to be a good record of such variability and reflects changes in the sedimentation on the rise when the ice sheet was probably closer to the continental shelf edge. An integrated age model has been provided for cores SED-12 and -13, which have the higher sedimentation rates
Rehabilitation of Neonatal Brachial Plexus Palsy: Integrative Literature Review
This integrative literature review has been carried out with the aim of analyzing the scientific literature aimed at identifying and describing existing rehabilitation treatments/therapies for neonatal brachial plexus palsy (NBPP). NBPP is a frequent consequence of difficult birthing, and it impairs the function of the brachial plexus in newborns. This is why knowledge on rehabilitation strategies deserves special attention. The data collection was carried out in January 2019, in the EBSCOhost and BVS (Biblioteca Virtual em Saúde) platforms, in the CINAHL Complete, MEDLINE Complete, LILACS and PubMed databases. Thirteen articles were included in this integrative literature review, based on a literature search spanning title, abstract and full text, and considering the inclusion criteria. Two main treatments/therapies for NBPP rehabilitation were identified: conservative treatment and surgical treatment. Conservative treatment includes teamwork done by physiatrists, physiotherapists and occupational therapists. These professionals use rehabilitation techniques and resources in a complementary way, such as electrostimulation, botulinum toxin injection, immobilizing splints, and constraint induced movement therapy of the non-injured limb. Professionals and family members work jointly. Surgical treatment includes primary surgeries, indicated for children who do not present any type of spontaneous rehabilitation in the first three months of life; and secondary surgeries, recommended in children who after primary surgery have some limitation of injured limb function, or in children who have had some spontaneous recovery, yet still have significant functional deficits. Treatment options for NBPP are defined by clinical evaluation/type of injury, but regardless of the type of injury, it is unanimous that conservative treatment is always started as early as possible. It should be noted that there was no evidence in the literature of other types of rehabilitation and techniques used in clinical practice, such as preventive positioning of contractures and deformities, hydrotherapy/aquatic therapy, among others, so we consider there is a need for further studies at this level in this area.info:eu-repo/semantics/publishedVersio
Paleomagnetic constraints on the Plio-Pleistocene geodynamic evolution of the external central-northern Apennines (Italy)
We report on new paleomagnetic results obtained from 27 sites sampled in the Plio-Pleistocene sequences at the external front of the central-northern Apennines. Previous analyses of Miocene (Messinian) sediments indicated that the present shape of the northern Apenninic arc is due to the oroclinal bending of an originally straight belt oriented around N320° and that vertical axis rotations accompanied the migration of the thrust fronts toward the Adriatic
foreland [F. Speranza et al., J. Geophys. Res. 102 (1997) 3153-3166]. We tried to provide new paleomagnetic constraints for the timing and rates of the oroclinal bending process during the Pliocene and the Pleistocene. The results suggest that CCW rotations observed in the northern part of the studied area are possibly younger than 3 Ma. No regional rotation is recorded in the Pliocene and Pleistocene sediments from the southern part of the study area, analogously to the Messinian sediments of the 'Acquasanta' domain of Speranza et al. [F. Speranza et al., J. Geophys. Res. 102 (1997) 3153-3166]. A local significant CCW rotation (23° ± 10°) is identified in the Early Pleistocene sediments that crop out along the Adriatic coast between Ascoli and Pescara, indicating differential motion of the thrust sheets. This rotation must be younger than 1.43 Ma
Palaeomagnetic results from an archaeological site near Rome (Italy): new insights for tectonic rotation during the last 0.5 Myr
Approximately 20 km north-east of Rome, along the modern trace of the Tiburtina road, recent archaeological diggings have brought to light a system of aqueduct galleries constructed by Roman engineers. This site falls inside the Acque Albule Basin, a travertine plateau Upper Pleistocene in age, that has been interpreted as a rhombshaped pull-apart basin created by strike-slip faulting within a N-S shear zone. This study provides evidence that two narrow water channels of this aqueduct system were significantly deformed by tectonic movement that occurred subsequent to their construction (II-III century A.D.). The geometry of the deformation pattern is compatible with that expected for a shear zone bounded by N-S oriented, right-lateral faults. The palaeomagnetic study of the volcanic formation («Pozzolane Rosse» Formation, 457± 4 kyr) containing the Roman aqueduct system evidences significant clockwise rotation around sub-vertical axis, consistent with the above-mentioned tectonic style
Орнаментальні форми кримськотатарського традиційного мистецтва
Historically Crimea was the land of culture of various tribes. And it had its influence on the Art style. The study of Crimea-Tatar Ornament dates to the 1880th. Its elements creates the system of symbols which gives the possibility to see the genetic ties of Crimea-Tatars with others ethnos. The author analyzed types of ornaments and their symbolic meanings
Core-mantle boundary deformations triggered by the Sumatra earthquake
The devastating megathrust earthquake of December 26 2004 off the west coast of northern Sumatra has been probably the largest since the 1960 Chile event. The occurrence of this event revived the debate, among the scientific community, upon several open geophysical problems possibly connected with the energy release of giant earthquakes. One of these problems concerns the origin of geomagnetic jerks and its eventual relationship with large seismic activity. Though a final answer to this question seems not to be at hand presently, this answer (whatever positive or negative) appears to be connected with the possibility that giant seismic events could cause significant changes in the CMB topography. Until now, no attempts have been made to compute the impact of a seismic event on the CMB: the great Sumatra earthquake, for the first time, gave unambiguous instrumental evidence that the deformation field associated with a giant event is detectable at distances up to several thousands of km with a magnitude of the displacements of the order of 1 mm. Since perturbations to the CMB even smaller than this value are likely to be able to produce a geomagnetic jerk, a precise evaluation of the CMB topography perturbation associated with a giant earthquake like Sumatra has become an important scientific question
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