236 research outputs found
GDS (Geomagnetic Depth Sounding) in Italy: applications and perspectives
No full textThe analysis of geomagnetic field variations is a useful tool to detect electrical conductivity contrasts within the Earth. Lateral resolution of outlined patterns depends on the array dimensions and density of measurement sites over the investigated area. The inspection depth is constrained by the period of geomagnetic variations considered in data processing. Regions with significant geological features such as boundaries of continental plates, marginal areas of contact between tectonic units or other geodynamical processes, are of primary interest for the application of the MagnetoVariational (MV) method. In the last ten years, in the frame of the ElectroMagnetic (EM) sounding techniques in applied geophysics, this method has been applied in Italy by researchers of the Istituto Nazionale di Geofisica, Rome, the Dipartimento di Scienze della Terra, Universitá di Genova and the Czech Science Academy of Prague. The Ivrea body in the Northwestern Alps and their junction with the Apennine chain, the micro-plate of the Sardinian-Corsican system and, recently, the central part of the peninsula along Tyrrhenian-Adriatic lithospheric transects were investigated. Studies in time and frequency-domain used in the first investigations, have been followed by more refined analysis involving tests on the induced EM field dimension, computations of single site Transfer Functions (TFs) through Parkinson arrows' and Fourier maps in the Hypothetical Event technique (HE). It was possible to describe the electrical conductivity distribution in the inner part of the SW Alpine arc and to confirm the presence of lithospheric and asthenospheric anomalies obtained by other geophysical methods. For the Sardinia-Corsica system, 2D and 3D inversion models highlighted the existence of two major conducting bodies, one north of Corsica, and the other south of Sardinia. In Central Italy, the regional electrical conductivity distribution pointed out a deep conductive structure beneath the Apennines and a very resistive root for this part of the mountain chain
Magnetotelluric investigations of the seismically active region of Northwest Bohemia: preliminary results
No full textComplete nucleotide sequence of an Indian isolate of Carnation etched ring virus and its homology with other caulimoviruses.
No full textCarnation etched ring virus (CERV) is a member of
Caulimovirus with double stranded DNA genome of
approx. 8 kb. CERV has been previously characterized
from Holland and the present article is an effort to
completely characterize the Asian isolate of CERV.
Primers were designed for amplification of all genes
encoded by the CERV, viz. movement protein, aphid
transmission factor, DNA binding protein, coat protein,
poly protein and inclusion body matrix genes, including
the complete genome. The CERV genome was sequenced
by amplifying the complete genome of CERV
using primers from 5¢- and 3¢-end and with internal
primers that amplify individual genes and parts of the
genes. The genome was found to comprise of 7924 bp,
with GC content of 37%. The different genes encoded
by CERV were compared with other known CERV
isolates and caulimoviruses. They were found most
conserved with respect to poly protein region (37–65%
amino acid similarity), while least with respect to inclusion
body matrix protein (5–37% amino acid similarity).
CERV isolates from India and Holland when compared
for different genes, showed 96–99% homology
between different genes at the amino acid level. Multiplex
PCR protocols were standardized to amplify
different genes of the CERV genome in one reaction.
Phylogenetic analysis based on different genes indicated
that CERV has independently evolved among caulimoviruses,
but is closely related to Cauliflower mosaic virus
Geomagnetic depth sounding in the Northern Apennines (Italy).
No full textA Geomagnetic Depth Sounding (GDS) survey covering the Northern Apennines of Italy has been carried out
in the period 1992–94. Induction arrows maps and hypothetical event Fourier maps were constructed to obtain an
electromagnetic imaging of this area. Since the two dimensional (2-D) character comes out from those maps for
periods greater than 32 minutes, a 2-D inverse modeling was carried out. The model responses show that a deep
conductive layer (>5000 S) underlies the Apennine chain at about 20 km depth. The transition between the Adriatic
and the Tyrrhenian domains is marked by a rather sharp vertical offset in this conducting layer. In the northwest
sector of the studied area an anomalous high conductivity behavior is superimposed on the regional trend, which
corresponds to the geothermal field of Larderello-Travale
Stochastic interpretation of magnetotelluric data, comparison of methods
No full textGlobal optimization and stochastic approaches to the interpretation of measured data have recently gained particular
attraction as tools for directed search for and/or verification of characteristic structural details and quantitative
parameters of the deep structure, which is a task often arising when interpreting geoelectrical induction
data in seismoactive and volcanic areas. We present a comparison of three common global optimization and stochastic
approaches to the solution of a magnetotelluric inverse problem for thick layer structures, specifically the
controlled random search algorithm, the stochastic sampling by the Monte Carlo method with Markov chains
and its newly suggested approximate, but largely accelerated, version, the neighbourhood algorithm. We test the
algorithms on a notoriously difficult synthetic 5-layer structure with two conductors situated at different depths,
as well as on the experimental COPROD1 data set standardly used to benchmark 1D magnetotelluric inversion
codes. The controlled random search algorithm is a fast and reliable global minimization procedure if a relatively
small number of parameters is involved and a search for a single target minimum is the main objective of the
inversion. By repeated runs with different starting test model pools, a sufficiently exhaustive mapping of the parameter
space can be accomplished. The Markov chain Monte Carlo gives the most complete information for the
parameter estimation and their uncertainty assessment by providing samples from the posterior probability distribution
of the model parameters conditioned on the experimental data. Though computationally intensive, this
method shows good performance provided the model parameters are sufficiently decorrelated. For layered models
with mixed resistivities and layer thicknesses, where strong correlations occur and even different model classes
may conform to the target function, the method often converges poorly and even very long chains do not guarantee
fair distributions of the model parameters according to their probability densities. The neighbourhood resampling
procedure attempts to accelerate the Monte Carlo simulation by approximating the computationally expensive
true target function by a simpler, piecewise constant interpolant on a Voronoi mesh constructed over a
set of pre-generated models. The method performs relatively fast but seems to suggest systematically larger uncertainties
for the model parameters. The results of the stochastic simulations are compared with the standard
linearized solutions both for thick layer models and for smooth Occam solutions.JCR Journalope
Adaptation of the questionnaire of experiences related to video games in young peruvians
No full textThe objective was to adapt the Questionnaire of Experiences Related to Video Games (CERV) for young people in Oxapampa, 2021. Following an instrumental design, the sample used consisted of 500 young men and women, aged 16 to 18 years, non-probabilistic snowball sampling. The CERV was modified to adapt it to sample sociocultural characteristics. The findings indicated an optimal Aiken’s V index, which implies that the items have an adequate degree of representativeness, clarity and relevance. The two-dimensional structure explained 63% of the variance of scores, dimensions: dependence and avoidance, and negative consequences. These obtained optimal fit indices in the confirmatory factor analysis (CMIN = 1.887; RMSEA = 0.042; IFC = 0.986; TLI = 0.993). Reliability analysis determined that the dimensions had adequate internal consistency (Ω > .80). It is concluded that the modified version of CERV demonstrated optimal validity and reliability, supporting its relevance for measuring video game dependence in this population.El objetivo fue adaptar el cuestionario de experiencias relacionadas con videojuegos (CERV) en jóvenes de Oxapampa, 2021. Siguiendo método instrumental, la muestra utilizada consistió en 500 jóvenes, hombres y mujeres, con edades de 16 a 18 años, usando el muestreo de bola de nieve no probabilístico. El CERV fue modificado para adaptarlo a características socioculturales de muestra. Los hallazgos indicaron existe índice óptimo de Aiken "V", que implica que los ítems tienen un grado adecuado de representatividad, claridad y relevancia. La estructura bidimensional explicó 63% de variabilidad de puntajes, dimensiones: dependencia y evitación, y consecuencias negativas, obtuvieron índices óptimos de ajuste mediante análisis factorial confirmatorio (CMIN = 1,887; RMSEA = 0,042; CFI = 0,986; TLI = 0,993), el análisis de confiabilidad determinó que las dimensiones tenían consistencia interna adecuada (Ω > ,80). Concluyéndose que la versión modificada del (CERV) evidencia óptima validez y confiabilidad en sus puntajes, que implica su relevancia para medir dependencia de videojuegos en población
Adaptação do questionário de experiências relacionadas a videogames em jovens peruanos.
No full textThe objective was to adapt the Questionnaire of Experiences Related to Video Games (CERV) for young people in Oxapampa, 2021. Following an instrumental design, the sample used consisted of 500 young men and women, aged 16 to 18 years, non-probabilistic snowball sampling. The CERV was modified to adapt it to sample sociocultural characteristics. The findings indicated an optimal Aiken’s V index, which implies that the items have an adequate degree of representativeness, clarity and relevance. The two-dimensional structure explained 63% of the variance of scores, dimensions: dependence and avoidance, and negative consequences. These obtained optimal fit indices in the confirmatory factor analysis (CMIN = 1.887; RMSEA = 0.042; IFC = 0.986; TLI = 0.993). Reliability analysis determined that the dimensions had adequate internal consistency (Ω > .80). It is concluded that the modified version of CERV demonstrated optimal validity and reliability, supporting its relevance for measuring video game dependence in this population.El objetivo fue adaptar el cuestionario de experiencias relacionadas con videojuegos (CERV) en jóvenes de Oxapampa, 2021. Siguiendo método instrumental, la muestra utilizada consistió en 500 jóvenes, hombres y mujeres, con edades de 16 a 18 años, usando el muestreo de bola de nieve no probabilístico. El CERV fue modificado para adaptarlo a características socioculturales de muestra. Los hallazgos indicaron existe índice óptimo de Aiken "V", que implica que los ítems tienen un grado adecuado de representatividad, claridad y relevancia. La estructura bidimensional explicó 63% de variabilidad de puntajes, dimensiones: dependencia y evitación, y consecuencias negativas, obtuvieron índices óptimos de ajuste mediante análisis factorial confirmatorio (CMIN = 1,887; RMSEA = 0,042; CFI = 0,986; TLI = 0,993), el análisis de confiabilidad determinó que las dimensiones tenían consistencia interna adecuada (Ω > ,80). Concluyéndose que la versión modificada del (CERV) evidencia óptima validez y confiabilidad en sus puntajes, que implica su relevancia para medir dependencia de videojuegos en población
Adaptación de la escala de experiencias relacionadas con los videojuegos (CERV) en estudiantes universitarios de Ate, 2022
No full textLa presente investigación tuvo como objetivo determinar las propiedades
psicométricas de la escala de experiencias relacionadas con los videojuegos
CERV en estudiantes universitarios de Ate, 2022. El diseño de estudio
instrumental, tipo aplicada, el cuestionario permite evaluar dos dimensiones,
dependencia y evasión, y consecuencias negativas, fue aplicado a una muestra
de 780 estudiantes universitarios. Obteniendo como resultados que los ítems
miden el constructo a través de la de la V de Aiken de 17 ítems que presenta el
cuestionario, viendo con el criterio de >0.8 para ser aprobados. La escala
mediante prueba de esfericidad de Bartlett tiene una significancia de 0.0 y KMO
de .661, mediante el análisis factorial confirmatorio la sectorización de las dos
dimensiones y cada una de ellas con los ítems idóneos para una medición
estadísticamente proporcional, se calculó la confiabilidad mediante el Alfa de
Cronbach de .873, por lo tanto, se afirma que la prueba es confiable. En
conclusión, el instrumento es válido y confiable para su aplicación y como
referente para futuras investigacione
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