1,721,159 research outputs found
Magnetic structural evidences of the 41° parallel zone (Tyrrhenian Sea) inferred from potential field data: the 3D model of the discontinuity
No full textPotential field data hold a leading role in the geologic-structural
application. Their use becomes even more important if applied
to extremely inaccessible zones as oceanic basins or no-antropized area. By an
areo-naval survey it is possible to cover large areas, in a short time, to
define their deep crustal features that are otherwise not accessible
by other direct methods. The analysis of the magnetic field data is
particularly
effective in the study of the crustal portions characterized by lateral
variation of the magnetic susceptibility. The magnetic analysis is often
applied to areas where sub-volcanic bodies or relic portion of
oceanic nature in sedimentary deposits are located.
The aim of this thesis is the development of a tridimensional model about
the 41st parallel zone starting from potential field data.
The name 41st parallel indicates a geographic zone aligned along
N41st of latitude. This area is longitudinally defined between the
Continental Campanian Margin (Naplean Gulf, Ischia and Procida island) and
the northwestern portion of the Sardinia Island.
From a geological point of view, the 41st parallel represents a
complicate area. Several geological structures are located along this zone:
submerged volcanic bodies such as the Etruschi,
Vercelli and Cassinis seamounts, emerged edifices connected to the
Pliocenic-Quaternary volcanism of the Central Tyrrhenian sea (Palmarola,
Zenone, Ponza, Ischia and Procida) and several
deep fault structures such as the E-W fault of Ponza.
The formation and the development of this particular zone is not clear and
is still object of discussion in literature. The structural setting of
41st
parallel zone is highlighted only by magnetic field data. By the
observation of the magnetic anomalous field it is possible to see an
alignment of several magnetic anomalies along the N41st latitude.
These anomalies take place on the main structural evidences of the area.
The bathymetric data and information don't suggest
these features. To this aim, I use the magnetic data to analyse in quantitative
way, the 41st parallel zone.
The magnetic data used for the development of the 3D magnetic model derived by
the dataset of the Aeromagnetic Anomaly Map of Italy (Caratori Tontini
et al., 2004).
The original magnetic dataset includes the total intensity field
of Italy and its surrounding seas acquired partly during the aeromagnetic
surveys performed by Agip (now Eni-Spa) between 1971 and 1980 and during
new surveys in the years 2001-2002(Eni,Exploration & Production Division -
Igmar, La Spezia). The magnetic data were recorded, in a homogeneous way,
by using a cesium-magnetometer.
By the successive reprocessing of the row magnetic data
the revised magnetic anomaly map is obtained showing a strong
informative contribution and a good agreement with the sea-level
map of Chiappini et al. (2002).
In the first chapter of this thesis I describe the geological and structural
features of the Tyrrhenian sea in general way. However, I analyse the
41st parallel zone starting from the literature data. In the second
chapter I evaluate the Bouguer gravity field of the Tyrrhenian Sea by using
two methodologies for an evaluation of the optimal Bouguer reduction density.
Using a free-air gravimetric satellite data set of the Tyrrhenian sea, I
perform a map of isostatic level of the central Tyrrhenian area. In the third
chapter I describe the properties of the Geomagnetic field and its
representation focusing my interest on the time and spatial dependencies of the
field. The successive section provides information about the row magnetic
data used for the quantitative
elaboration describing the characteristics of the anomaly field of the
studied area. In the fifth chapter, the properties of the magnetic signal is
studied by using a statistical analysis of the power spectrum
(Spector and Grant, 1970) and by the Continuous Wavelet Transform.
After these analyses, in the sixth chapter I introduce the concept of magnetic
basement and the relationship between magnetic signal and temperature.
Starting from
the regional heat-flow data (Della Vedova et al., 2001) of the Central
Tyrrhenian area the Curie Isotherm surface is modeled defining the
maximum depth of the magnetic-thermal basement. The boundaries of the
magnetic sources (top and bottom) represents the base-line for the successive
phases of quantitative analysis.
By using a 2D inversion algorithm I obtain
the map of apparent susceptibility. In the seventh chapter, I apply this
algorithm to the magnetic evidence of the 41st parallel zone and to
the Selli Line region. This procedure suggests a distribution of magnetization
that permits to connect the 41st parallel zone and the structural
elements of the Southern Tyrrhenian Sea such as the Magnaghi Basin and the
Selli Line faults system.
Starting form the results obtained by the apparent magnetization maps,
I perform a 3D inversion of magnetic data providing information about the
vertical distribution of the sources. In the eighth chapter,
that represents an important part of the thesis, I introduce the inverse
problem in the potential field analysis by a new 3D algorithm capable to
evaluate the depth to the bottom of the source.
Then, I apply this algorithm to the real magnetic dataset of the
41st and Selli Line regions. The recovered models show the shape,
location in depth and direction of development
of the magnetic generating sources suggesting the geometric relationship
between the different sources. These information are important for evaluating
the crustal setting of the study area. Finally, in the last
chapter I interpret the results of inversion process evaluating
the relationship between the 41 st
parallel and the Selli Line region. Starting from the magnetic recovered models
of these two regions I provide a chronological reconstruction of the geodynamic
evolution of the Central Tyrrhenian Sea.Università di BolognaUnpublished3.3. Geodinamica e struttura dell'interno della Terra3.4. Geomagnetismo3.5. Geologia e storia dei sistemi vulcaniciope
Magnetic structural evidences of the 41° parallel zone (Tyrrhenian Sea) inferred from potential field data: the 3D model of the discontinuity
No full textPotential field data hold a leading role in the geologic-structural
application. Their use becomes even more important if applied
to extremely inaccessible zones as oceanic basins or no-antropized area. By an
areo-naval survey it is possible to cover large areas, in a short time, to
define their deep crustal features that are otherwise not accessible
by other direct methods. The analysis of the magnetic field data is
particularly
effective in the study of the crustal portions characterized by lateral
variation of the magnetic susceptibility. The magnetic analysis is often
applied to areas where sub-volcanic bodies or relic portion of
oceanic nature in sedimentary deposits are located.
The aim of this thesis is the development of a tridimensional model about
the 41st parallel zone starting from potential field data.
The name 41st parallel indicates a geographic zone aligned along
N41st of latitude. This area is longitudinally defined between the
Continental Campanian Margin (Naplean Gulf, Ischia and Procida island) and
the northwestern portion of the Sardinia Island.
From a geological point of view, the 41st parallel represents a
complicate area. Several geological structures are located along this zone:
submerged volcanic bodies such as the Etruschi,
Vercelli and Cassinis seamounts, emerged edifices connected to the
Pliocenic-Quaternary volcanism of the Central Tyrrhenian sea (Palmarola,
Zenone, Ponza, Ischia and Procida) and several
deep fault structures such as the E-W fault of Ponza.
The formation and the development of this particular zone is not clear and
is still object of discussion in literature. The structural setting of
41st
parallel zone is highlighted only by magnetic field data. By the
observation of the magnetic anomalous field it is possible to see an
alignment of several magnetic anomalies along the N41st latitude.
These anomalies take place on the main structural evidences of the area.
The bathymetric data and information don't suggest
these features. To this aim, I use the magnetic data to analyse in quantitative
way, the 41st parallel zone.
The magnetic data used for the development of the 3D magnetic model derived by
the dataset of the Aeromagnetic Anomaly Map of Italy (Caratori Tontini
et al., 2004).
The original magnetic dataset includes the total intensity field
of Italy and its surrounding seas acquired partly during the aeromagnetic
surveys performed by Agip (now Eni-Spa) between 1971 and 1980 and during
new surveys in the years 2001-2002(Eni,Exploration & Production Division -
Igmar, La Spezia). The magnetic data were recorded, in a homogeneous way,
by using a cesium-magnetometer.
By the successive reprocessing of the row magnetic data
the revised magnetic anomaly map is obtained showing a strong
informative contribution and a good agreement with the sea-level
map of Chiappini et al. (2002).
In the first chapter of this thesis I describe the geological and structural
features of the Tyrrhenian sea in general way. However, I analyse the
41st parallel zone starting from the literature data. In the second
chapter I evaluate the Bouguer gravity field of the Tyrrhenian Sea by using
two methodologies for an evaluation of the optimal Bouguer reduction density.
Using a free-air gravimetric satellite data set of the Tyrrhenian sea, I
perform a map of isostatic level of the central Tyrrhenian area. In the third
chapter I describe the properties of the Geomagnetic field and its
representation focusing my interest on the time and spatial dependencies of the
field. The successive section provides information about the row magnetic
data used for the quantitative
elaboration describing the characteristics of the anomaly field of the
studied area. In the fifth chapter, the properties of the magnetic signal is
studied by using a statistical analysis of the power spectrum
(Spector and Grant, 1970) and by the Continuous Wavelet Transform.
After these analyses, in the sixth chapter I introduce the concept of magnetic
basement and the relationship between magnetic signal and temperature.
Starting from
the regional heat-flow data (Della Vedova et al., 2001) of the Central
Tyrrhenian area the Curie Isotherm surface is modeled defining the
maximum depth of the magnetic-thermal basement. The boundaries of the
magnetic sources (top and bottom) represents the base-line for the successive
phases of quantitative analysis.
By using a 2D inversion algorithm I obtain
the map of apparent susceptibility. In the seventh chapter, I apply this
algorithm to the magnetic evidence of the 41st parallel zone and to
the Selli Line region. This procedure suggests a distribution of magnetization
that permits to connect the 41st parallel zone and the structural
elements of the Southern Tyrrhenian Sea such as the Magnaghi Basin and the
Selli Line faults system.
Starting form the results obtained by the apparent magnetization maps,
I perform a 3D inversion of magnetic data providing information about the
vertical distribution of the sources. In the eighth chapter,
that represents an important part of the thesis, I introduce the inverse
problem in the potential field analysis by a new 3D algorithm capable to
evaluate the depth to the bottom of the source.
Then, I apply this algorithm to the real magnetic dataset of the
41st and Selli Line regions. The recovered models show the shape,
location in depth and direction of development
of the magnetic generating sources suggesting the geometric relationship
between the different sources. These information are important for evaluating
the crustal setting of the study area. Finally, in the last
chapter I interpret the results of inversion process evaluating
the relationship between the 41 st
parallel and the Selli Line region. Starting from the magnetic recovered models
of these two regions I provide a chronological reconstruction of the geodynamic
evolution of the Central Tyrrhenian Sea.Università di BolognaUnpublished3.3. Geodinamica e struttura dell'interno della Terra3.4. Geomagnetismo3.5. Geologia e storia dei sistemi vulcaniciope
Depth-to-the-bottom optimization for magnetic data inversion: Magnetic structure of the Latium volcanic region, Italy
No full textWe present an algorithm for the linear inversion of two-dimensional (2-D) surface magnetic data to obtain 3-D models of the susceptibility of the source. The forward model is discretized by a mesh of prismatic cells with constant magnetization that allows the recovery of a complete 3-D generating source. As the number of cells are normally greater than the amount of available data, we have to solve an underdetermined linear inverse problem. A Tikhonov regularization of the solution is introduced as a depth-weighting function adapted from Li and Oldenburg (1996) to close the source toward the bottom. The main novelty of this method is a first-stage optimization that gives information about the depth to the bottom of the generating source. This parameter permits both the evaluation of the appropriate vertical extension of the mesh and the definition of the shape of the regularizing depth-weighting distribution. After discussing the performance of this method by showing the results of various synthetic tests, we invert the magnetic anomalies of the volcanic edifices in the Latium region in central Italy to define their 3-D source distribution. Copyright 2006 by the American Geophysical Union
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
The Trees of the Pisa Botanic Garden under Climate Change Scenarios: What Are We Walking into?
Full text linkBotanical gardens are dynamic systems of high scientific, ecological, cultural, and historical value. They are irreplaceable places to cultivate, manage, study, and preserve tree diversity. One of the ongoing biggest challenges worldwide in managing and preserving trees is climate change, which exposes specimens to more stressful and severe environmental conditions, causing an increase in mortality. In our research, we aimed to assess the future climate change impact on the tree collection of Botanic Garden of Pisa in order to outline the expected consequences about tree cultivation and management. Under the most pessimistic scenario, in 2090 more than 60% of the tree species cultivated in the Botanic Garden of Pisa are expected to fall outside of their climatic niche. Future chances and pitfalls in managing urban green areas, focusing on the botanical garden community, are also explored
Endogenous sex hormones affect the mutagen-induced chromosome damage by altering a caffeine-sensitive checkpoint
No full textIn the present study we analysed the effect of endogenous sex hormones on the SCE frequencies induced in vitro by mitomycin C (MMC), a bifunctional alkylating agent producing high chromosome damage and mitotic arrest. The analysis has been performed on lymphocytes obtained at three different phases of menstrual cycle, from women with regular cycle and hormones dosage. At all phases we further analysed the effect of a post-treatment with caffeine, an agent that it is known to overrride the DNA damage checkpoints. After MMC, the cultures obtained at ovulation and luteal phases have SCE frequencies statistically higher than the cultures obtained at the progestogenic phase, showing increases of 15 and 25%, respectively. After caffeine, the MMC treated cultures which were set up at the progestogenic phase show a high potentiation of SCE frequencies (28%) whereas the treated cultures set up at ovulatory and luteal phases show little or no potentiation. These findings demonstrate that the endogenous hormones greatly modulate the SCE frequencies induced by the mutagen; they also indicate that hormones action competes with the caffeine effect. Caffeine acts by abrogating the mitotic arrest produced by DNA damage and induced cells with a higher chromosome damage into a premature mitosis. Our findings suggest that endogenous hormones could overcome the checkpoint controls activated in cells after mutagenic exposure. This action may be an epigenetic mechanism relevant in hormone carcinogenesis. © 2004 Elsevier B.V. All rights reserved
Reply to the comment by Trua (2024) on Gennaro et al. (2023), Lithos 456–457, 107325, Large silicic magma chambers at the Moho depth characterize the multi-level plumbing system of back-arc spreading ridges
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