4,922 research outputs found
Geomagnetic field observations in Antarctica at the geomagnetic observatories at Terra Nova Bay and DomeC
During the 1986-87 austral summer a geomagnetic observatory was installed at the Italian Antarctic Base
Mario Zucchelli Station (TNB, geographic coordinates:74.7S, 164.1E; corrected geomagnetic coordinates:
80.0S, 307.7E; magnetic local time MLT=UT-8). In the first years the measurements of the geomagnetic field
were carried out only during summer expeditions. Since 1991 the recording was implemented with an
automatic acquisition system operating through the year. More recently,after two short test surveys, from
October 2004 a geomagnetic French-Italian observatory was installed on the Antarctic plateau (Dome C,
DMC), very close to the geomagnetic pole (geographic coordinates: 75.1S, 123.4E; corrected geomagnetic
coordinates:88.8S, 55.6E; magnetic local time MLT=UT-1). In this work we present some results obtained
from TNB observations coming from almost twenty years of observations and also the preliminary results
obtained from the analysis of the first year of data from DMC
EARTH'S MAGNETISM AT THE SOUTH POLE: A VIEW FROM INLAND AND COASTAL STATIONS AND FROM TEMPORARY INSTALLATIONS
Contributions to the knowledge of the Earth’s magnetism from polar regions is extremely important to understand the planetary phenomena which occur both below and above the Earth’s surface. At those areas the Earth’s magnetic field is stronger and the spatial and temporal changes are enhanced. At the same time polar regions are areas scarcely covered by observations for the adverse environmental conditions. We report the experience gained in years of management and maintenance of permanent stations (Mario Zucchelli, Dumont d’Urville (Victoria Land) and Concordia stations, Dome C) as well as temporary installations (Talos Dome) in Antarctica, showing how different acquisition systems, analysis and interpretation of data allow the scientific communities to contribute to originating important theories, models and results
Fourteen years of geomagnetic daily variation at Mario Zucchelli Station (Antarctica)
During the 1986-87 austral summer a geomagnetic observatory was installed
at the Italian Antarctic Base Mario Zucchelli Station. In the first three years
continuous time variation monitoring and absolute measurements of the
geomagnetic field were carried out only during summer expeditions. Starting
1991 an automatic acquisition system, operating through all the year, was put
in operation. We present here some peculiarities of the daily variation as
observed for fourteen years (1987-2000). The availability of a long series of
data has allowed the definition of seasonal, as well as solar cycle effects, on
short time variations as observed at a cusp-cap observatory. In particular,
contrary to mid latitude behaviour, a clear dependence of the daily variation
amplitude on the global geomagnetic K index was well defined
Geomagnetic field observations in Antarctica at the geomagnetic observatories at Terra Nova Bay and DomeC
During the 1986-87 austral summer a geomagnetic observatory was installed at the Italian Antarctic Base
Mario Zucchelli Station (TNB, geographic coordinates:74.7S, 164.1E; corrected geomagnetic coordinates:
80.0S, 307.7E; magnetic local time MLT=UT-8). In the first years the measurements of the geomagnetic field
were carried out only during summer expeditions. Since 1991 the recording was implemented with an
automatic acquisition system operating through the year. More recently,after two short test surveys, from
October 2004 a geomagnetic French-Italian observatory was installed on the Antarctic plateau (Dome C,
DMC), very close to the geomagnetic pole (geographic coordinates: 75.1S, 123.4E; corrected geomagnetic
coordinates:88.8S, 55.6E; magnetic local time MLT=UT-1). In this work we present some results obtained
from TNB observations coming from almost twenty years of observations and also the preliminary results
obtained from the analysis of the first year of data from DMC
Oxidative stress neuroinflammation and cellular stress response in sensorineural hearing loss: novel nutritional therapeutical approaches
This study is intended to validate the hypothesis that changes in the redox state of glutathione, the major endogenous antioxidant, associated with the abnormal expression and activity of cytoprotective vitagenes, which in normal conditions are expressed only at low level may represent a critical factor, involved in the physiopathological changes associated to degenerative damage occurring in cochlear diseases. Moreover modulation of stress responsive vitagenes by nutritional antioxidants can be an effective therapeutic strategy to minimize consequences of oxidative stress associated to the pathogenesis and course of sensorineural hearing loss. One therapeutic approach can be antioxidant substances, as cisteina and superoxide dismutase supplementation to burst vitagenes and confer neuroprotection. The damage caused in the inner ear by oxidative stress can induce apoptosis and necrosis of both the hair cells as neurons of the spiral ganglion. Reactive oxygen species (ROS) and free radicals are formed not only as by-products of various metabolic pathways but also for exposure to ototoxic substances such as aminoglycosides and cisplatin, for hypoxia/ischemia and to exposure to noise. Although the mechanism of production of ROS within the cochlea has not yet been precisely identified, it is conceivable that mitochondrial dysfunction and consequent burst in oxidative stress are major causative factors. Consistent with this notion, it is known that the base of the cochlea is more vulnerable to oxidative damage resulted from exposure to ototoxic substances than the apical portions. The difference in survival between the basal outer hair cells and the apical ones appear to be due to a significantly lower level of glutathione in the basal outer hair cells than the apical, a phenomenon that makes it easier basal cells vulnerable to damage from free radicals. © Mattioli 188
Fourteen years of geomagnetic daily variation at Mario Zucchelli Station (Antarctica)
During the 1986-87 austral summer a geomagnetic observatory was installed
at the Italian Antarctic Base Mario Zucchelli Station. In the first three years
continuous time variation monitoring and absolute measurements of the
geomagnetic field were carried out only during summer expeditions. Starting
1991 an automatic acquisition system, operating through all the year, was put
in operation. We present here some peculiarities of the daily variation as
observed for fourteen years (1987-2000). The availability of a long series of
data has allowed the definition of seasonal, as well as solar cycle effects, on
short time variations as observed at a cusp-cap observatory. In particular,
contrary to mid latitude behaviour, a clear dependence of the daily variation
amplitude on the global geomagnetic K index was well defined
Geomagnetic polar observatories: the role of Concordia station at Dome C, Antarctica
A geomagnetic observatory is a permanent facility where magnetic
declination and inclination are recorded in conjunction with the temporal
evolution of the magnetic field components. Polar regions are
scarcely covered by observational points then the contributions from observatories
located there are particularly relevant. The geomagnetic observatory
at Concordia station, Dome C - Antarctica is located in the
inner part of the continent, its position is favorable for two key reasons,
i) data are unaltered by the "coastal effect” and ii) crustal effect
is negligible due to the thickness, almost 3 km, of ice coverage. Nevertheless,
these latter conditions imply an unconsidered aspect which
characterizes the entire station and every structure laying on the ice
surface: the dome on which Concordia station resides is sliding horizontally
and moving vertically with a velocity of few millimeter to
centimeters per year as indicated by independent geodetic observations.
This slow and continuous movement has a puzzling effect on the
trend of horizontal components of the magnetic field, sampled in a
time window of a decade since the establishing of the observatory in
2005.During the International Polar Year (2007-2009) the observatory
was upgraded with new equipment fulfilling the requirements of the
Intermagnet consortium, and becoming an observatory member in
2011. In this paper are illustrated the strategy adopted to track any possible
displacement of the observatory reference points (i.e. the azimuth
mark, the pillar position) and all the ordinary and extraordinary actions
required for collecting high quality data
Two-photon excitation and relaxation of the 3d-4d resonance in atomic Kr
Two-photon excitation of a single-photon forbidden Auger resonance has been observed and investigated using the intense extreme ultraviolet radiation from the free electron laser in Hamburg. At the wavelength 26.9 nm (46 eV) two photons promoted a 3d core electron to the outer 4d shell. The subsequent Auger decay, as well as several nonlinear above threshold ionization processes, were studied by electron spectroscopy. The experimental data are in excellent agreement with theoretical predictions and analysis of the underlying multiphoton processes
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