1,721,027 research outputs found
Strategies to Promote Vaccine Uptake in the COVID-19 Pandemic: Exploring the "Ladder of Intrusiveness" in Three Countries
Get PDFContext: A key task for countries around the world facing the COVID-19 pandemic was to achieve high vaccination coverage of the population. To overcome "vaccination inertia," governments adopted a variety of policy instruments. These instruments can be placed along a "ladder of intrusiveness" based on their degree of constraint of individual freedoms. The aim of this study is to investigate how the governments of three European countries moved along the ladder of intrusiveness and how the choice of policy instruments was influenced by contextual factors. Methods: The study draws on secondary data sources, including academic and gray literature, policy documents, and opinion polls, over an observation period from December 2020 to summer 2022. The study employs inductive logic to analyze data and identify the factors explaining similarities and differences across England, Germany, and Italy. Findings: The study identifies similarities and differences in how the three countries advanced along the ladder of intrusiveness. Contextual factors such as policy legacy, social acceptability, and ideological orientation contribute to explain the observations. Conclusions: Country-specific contextual factors play an important role in understanding the choice of policy instruments adopted by the three countries. Policy makers should carefully consider these factors when planning immunization strategies
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Seismic attenuation and rheology of crustal rocks: results from numerical tests
No full textSeismic attenuation of the rocks mainly depends on their intrinsic anelasticity, which is the
dissipation of seismic energy as it propagates through the medium. Several studies have already
demonstrated that seismic attenuation, described by the Q-factor, is intrinsically related to the
rocks’ viscosity, considering their common dependency on composition, grain size, fluid content,
and T-P conditions. However, viscous deformation of the rocks occurs through different
mechanisms: diffusion creep, numerous mechanisms of the dislocation creep, pressure solution,
which are expressed by several Arrhenius-type constitutive laws. This makes more complex the
investigation of quantitative relationships between seismic attenuation and viscous rocks'
rheology.
The main purpose of this study is to investigate the mutual dependence of the seismic attenuation
and viscous deformation of the crustal rocks. To this aim, we performed several numerical tests to
check the variability of some physical properties (e.g., elastic modulus, Poisson’s ratio) and
improve the existing relationships between seismic attenuation and viscous deformation of
several natural rock samples. The Burgers mechanical model and Arrhenius relation are included
in these test series to achieve a closer approximation of the rocks’ viscous deformation.
In this way, it will be possible to predict the viscous rheology of rocks from the laws describing the
seismic attenuation and viceversa. The obtained results will be used to (1) constrain the Q-factor
and rheological (creep) parameters, which are still subjected to high uncertainties, (2)
validate/modify the existing seismic attenuation and rheological laws, (3) increase the robustness
of the geodynamic and rocks’ mechanics numerical codes and our understanding of the role that
rocks’ rheology exerts on the tectonic processe
How does seismic attenuation correlate to rheology of crustal rocks? Results from a numerical approach
Get PDFMost natural resources are distributed within the uppermost layer of the lithosphere and their exploitation is
limited by the transition from brittle to ductile rocks’ deformation (BDT), which coincides with a strong
reduction in rocks permeability. Therefore, knowledge of the physical and mechanical crustal properties is
crucial for improving our understanding of the exploitable potential. Previous studies have showcased the ex-
istence of a relation between rocks’ seismic attenuation and their viscous modes of deformations, considering
that both depend on intrinsic rocks characteristics (e.g., grain size, fluid content) and background P-T conditions.
In this study, we investigate such quantitative relationships between seismic attenuation and viscous rocks’
rheology across the domain where rocks transition from a dominant brittle to a more ductile deformation mode.
We rely on the Burgers and Gassmann mechanical model to derive shear wave attenuation (1/Qs), for several dry
and wet crustal rheology, thermal conditions, and different strain rates. This allows us to establish geothermal
and mechanical conditions at which the BDT occurs and cross-correlate this transition to computed shear seismic
wave attenuation values. In particular, we observe that Qs variation with depth is more sensitive to the input
strain rate than to the adopted rock‘s rheology and thermal conditions, so that a fixed amount of the Qs reduction
can be used to identify the average BDT depths for each strain rate used. Below the BDT depth, we observe a
significant drop in Qs (up to 10-4 % of the surface value), being also influenced by the background temperature
and rock rheology. Since the greatest Qs reduction is estimated for the highest input strain rate (10-13 s-1), our
results have implications for tectonically active/geothermal areas. Ongoing and future works will focus on a
further validation of the modelling implications by systematic analyses of observations derived from rocks’
laboratory experiments. The last ones can add constraints on the relationship found in this study between seismic
attenuation and adopted rheological flow law
How does seismic attenuation correlate to rheology of crustal rocks? First results from a numerical approach
No full textIntrinsic anelasticity of crustal rocks causes energy dissipation of seismic waves when they
propagate through the media. This dissipated energy can be quantified in terms of a seismic quality
factor (Q), which can be used as a potential attribute for subsurface characterization. This parameter
depends on the seismic frequency, as well as on temperature, water content, and grain size of the
rocks (e.g., Karato & Spetzler, 1990; Jackson & Faul, 2010). On the other hand, the viscous
deformation of crustal rocks occurs through different anelastic mechanisms including diffusion creep,
numerous mechanisms of the dislocation creep, pressure solution that exhibits dependency on their
structure, composition, and fluid content, as well as on their P-T conditions (e.g., Burov, 2011).
Therefore, it is likely that seismic attenuation and the viscous modes of deformations of rocks can be
correlated, based on their dependency on the aforementioned conditions, as expressed by an
Arrhenius-type equation (Farina et al., 2019).
In this study, we investigate the quantitative relationships between seismic attenuation and
viscous rocks' rheology, especially across the domain where rocks transition from a dominant brittle
to a more ductile deformation mode (Brittle Ductile Transition, BDT). We rely on a Burgers
mechanical model to derive shear wave attenuation (1/Qs
), for several dry and wet crustal rheology,
thermal conditions, and different strain rates values. This allows us to establish geothermal and
mechanical conditions at which the BDT occurs and to cross-correlate this transition to computed
shear seismic wave attenuation values. In particular, we observe a relatively significant Qs
reduction
for strain rates of 10-13 s
-1
, despite the assumed rock‘s rheology and thermal conditions. These first
results confirm our hypothesis that variations in the Qs
factor can be effectively used to identify the
BDT’s depths in tectonically active areas. Ongoing and future works will focus on a further validation
of the modelling implications by systematic analyses of observations derived from rocks’ laboratory
experiments, which can add constraints on the relationship between seismic attenuation and
rheological flow laws
Modeling approach to estimate seismic attenuation from dry and wet upper crustal rock’s rheology
No full textThe elementary definition of the attenuation is referred to the damped harmonic oscillator as the fractional loss
of energy per wave cycle. In some cases, it is used to describe the physical properties of the system that cause
a disturbance (Stein and Wysession, 2003). For instance, the energy decay over time of some of the Earth’s
normal modes (directly analogous to a damped oscillator), exhibits attenuation due to the material distribution
in the earth. The attenuation can be quantified in terms of the seismic quality factor Q. At given absorption
bands, Q can be considered nearly constant and can be related to the superposition of different mechanisms
that causes the conversion of seismic energy into internal heat. These mechanisms in turn depend on the
material composition and grain size and vary with temperature and pressure, such that higher pressure
decreases attenuation, whereas higher temperature promotes the opposite (Stein and Wysession, 2003). On
the other hand, the viscous deformation of crustal rocks occurs through different anelastic mechanisms,
including diffusion creep, numerous mechanisms of the dislocation creep, pressure solution that exhibits
dependency on their structure, composition, and fluid content, as well as on their P-T conditions (e.g., Burov,
2011). Therefore, it is likely that seismic attenuation and the viscous modes of deformations of rocks can be
correlated, based on their dependency on the aforementioned conditions, as expressed by an Arrhenius-type
equation (Farina et al., 2019).
Despite many studies provided indications that rocks’ seismic attenuation and viscous deformation are
intrinsically related (considering their common dependency on composition, grain size, fluid content, and T-P
conditions), their quantitative relationships have been very poorly investigated. In this study, we explore
plausible relationships, implementing a modeling strategy to derive seismic attenuation from diverse rock’s
rheologies and to quantitatively estimate the reduction in the Q factor in correspondence to the depth of the
brittle-to-ductile transition (BDT). For that, we rely on a Burgers mechanical model to derive shear wave
attenuation (1/Qs
), for several dry and wet crustal rheology, thermal conditions, and different strain rates values.
This allows us to establish geothermal and mechanical conditions at which the BDT occurs and to cross-correlate
this transition to computed shear seismic wave attenuation values.
In particular, we observe a relatively significant Qs
reduction (10-8
) for strain rates of 10-13 s
-1
, despite the
assumed rock‘s rheology and thermal conditions. These first results confirm our hypothesis that variations in
the Qs
factor can be effectively used to identify the depth to the BDT in tectonically active areas. This effect is
particular relevant in the presence of fluid saturated rheology (Figure 1).
Ongoing and future works will focus on a further validation of the modelling implications by systematic analyses
of observations, derived from rocks’ laboratory experiments, which will be used to add constraints on the
relationship between seismic attenuation and rheological flow laws to be used for geodynamic modelling
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