2,222 research outputs found
Impact of global seismicity on sea level change assessment
We analyze the effect of seismic activity on sealevel variations, by
computing the time-dependent vertical crustal movement and geoid change due to
coseismic deformations and postseismic relaxation effects. Seismic activity can
affect both the absolute sealevel, by changing the Earth gravity field and
hence the geoid height, and the relative sealevel, i.e. the radial distance
between seafloor and geoid level. By using comprehensive seismic catalogues we
assess the net effect of seismicity on tidal relative sealevel measurements as
well as on the global oceanic surfaces, and we obtain an estimate of absolute
sealevel variations of seismic origin.
Our results confirm that, on a global scale, most of the signal is associated
with few giant thrust events, and that RSL estimates obtained using tide-gauge
data can be sensibly affected by the seismic driven sealevel signal.
The recent measures of sealevel obtained by satellite altimetry show a wide
regional variation of sealevel trends over the oceanic surfaces, with the
largest deviations from the mean trend occurring in tectonically active
regions. While our estimates of average absolute sealevel variations turn out
to be orders of magnitude smaller than the satellite measured variations, we
can still argue that mass redistribution associated with aseismic tectonic
processes may contribute to the observed regional variability of sealevel
variations.Comment: 34 pages, submitted to Journal of Geophysical Researc
Modeling sea level changes and geodetic variations by glacial isostasy: the improved SELEN code
We describe the basic features of SELEN, an open source Fortran 90 program
for the numerical solution of the so-called "Sea Level Equation" for a
spherical, layered, non-rotating Earth with Maxwell viscoelastic rheology. The
Sea Level Equation was introduced in the 70s to model the sea level variations
in response to the melting of late-Pleistocene ice-sheets, but it can be also
employed for predictions of geodetic quantities such as vertical and horizontal
surface displacements and gravity variations on a global and a regional scale.
SELEN (acronym of SEa Level EquatioN solver) is particularly oriented to
scientists at their first approach to the glacial isostatic adjustment problem
and, according to our experience, it can be successfully used in teaching. The
current release (2.9) considerably improves the previous versions of the code
in terms of computational efficiency, portability and versatility. In this
paper we describe the essentials of the theory behind the Sea Level Equation,
the purposes of SELEN and its implementation, and we provide practical
guidelines for the use of the program. Various examples showing how SELEN can
be configured to solve geodynamical problems involving past and present sea
level changes and current geodetic variations are also presented and discussed
Extracting the top-quark running mass using +1-jet events produced at the Large Hadron Collider
We present the calculation of the next-to-leading order QCD corrections for
top-quark pair production in association with an additional jet at hadron
colliders, using the modified minimal subtraction scheme to renormalize the
top-quark mass. The results are compared to measurements at the Large Hadron
Collider run I. In particular, we determine the top-quark running mass from a
fit of the theoretical results presented here to the LHC data
On the AGN radio luminosity distribution and the black hole fundamental plane
We have studied the dependence of the AGN nuclear radio (1.4 GHz) luminosity
on both the AGN 2-10 keV X-ray and the host-galaxy K-band luminosity. A
complete sample of 1268 X-ray selected AGN (both type 1 and type 2) has been
used, which is the largest catalogue of AGN belonging to statistically well
defined samples where radio, X and K band information exists. At variance with
previous studies, radio upper limits have been statistically taken into account
using a Bayesian Maximum Likelihood fitting method. It resulted that a good fit
is obtained assuming a plane in the 3D L_R-L_X-L_K space, namely logL_R= xi_X
logL_X + xi_K logL_K + xi_0, having a ~1 dex wide (1 sigma) spread in radio
luminosity. As already shown, no evidence of bimodality in the radio luminosity
distribution was found and therefore any definition of radio loudness in AGN is
arbitrary. Using scaling relations between the BH mass and the host galaxy
K-band luminosity, we have also derived a new estimate of the BH fundamental
plane (in the L_5GHz -L_X-M_BH space). Our analysis shows that previous
measures of the BH fundamental plane are biased by ~0.8 dex in favor of the
most luminous radio sources. Therefore, many AGN studies, where the BH
fundamental plane is used to investigate how AGN regulate their radiative and
mechanical luminosity as a function of the accretion rate, or many AGN/galaxy
co-evolution models, where radio-feedback is computed using the AGN fundamental
plane, should revise their conclusions.Comment: Submitted to MNRAS. Revised version after minor referee comments. 12
pages, 12 figure
A spatial model for sporadic tree species distribution in support of tree oriented silviculture
This technical note describes how a spatial model for sporadic tree species distribution in the territory of the Unione di Comuni Montana Colline Metallifere (UCMCM) was built using the Random Forest (RF) algorithm and 48 predictors, including reflectance values from ground cover - provided by satellite sensors - and ecological factors. The P.Pro.SPO.T. project - Policy and Protection of Sporadic tree species in Tuscany forest (LIFE 09 ENV/IT/000087) is currently carried out in this area with the purpose of initiating the implementation of tree oriented silviculture in the Tuscany forests. Tree oriented silviculture aims at obtaining both forest biodiversity protection and local production of valuable timber. After creating a map showing the probability of presence of sporadic tree species, it was possible to identify the most suitable areas for sporadic tree species which are under protection according to the regulation of the Tuscany Region.Using data and software provided free of charge, and applying the RF algorithm, distribution models could be developed in order to identify the most suitable areas for the application of tree oriented silviculture. This can provide a support to forestry planning that includes tree oriented silviculture, thus reducing its implementation cost
HPC in global geodynamics: Advances in normal-mode analytical modeling
Analytical models based on normal-mode theory have been successfully employed for decades in the modeling of global response of the Earth to seismic dislocations, postglacial rebound and wave propagation. Despite their limited
capabilities with respect to fully numerical approaches, they are yet a valuable modeling tool, for instance in benchmarking applications or when automated procedures
have to be implemented, as in massive inversion problems when a large number of forward models have to be solved. The availability of high-performance computer systems ignited new applications for analytical modeling, allowing to remove limiting approximations and to carry out extensive simulations on large global datasets
On the earthquake predictability of fault interaction models
Space-time clustering is the most striking departure of large earthquakes occurrence process from randomness. These clusters are usually described ex-post by a physics-based model in
which earthquakes are triggered by Coulomb stress changes induced by other surrounding earthquakes. Notwithstanding the popularity of this kind of modeling, its ex-ante skill in terms of earthquake predictability gain is still unknown. Here we show that even in synthetic systems that are rooted on the physics of fault interaction using the Coulomb stress changes, such a kind of modeling often does not increase significantly earthquake predictability. Earthquake predictability of a fault may increase only when the Coulomb stress change induced by a nearby earthquake is much larger than the stress changes caused by earthquakes on other faults and by the intrinsic variability of the earthquake occurrence process
Quality and properties of titanium used in orthopedic surgery
Puesto que en los momentos actuales se está usando el titanio de manera habitual como componente de todas las endoprótesis, y de manera cada vez más importante se está incluyendo en la fabricación de los implantes de osteosíntesis y estabilización osteoarticular, es necesario que los cirujanos ortopédicos nos acerquemos al conocimiento de sus bondades o de sus inconvenientes.
Tratamos por ello de situarlo en sus coordenadas de aplicación clínica, resaltando sus virtudes en los aspectos biomecánicos, en las garantías de biocompatibilidad que permiten que se pueda realizar por parte del hueso receptor el fenómeno de la osteointegración, y en general en la respuesta del huésped ante este metal no desde el punto de vista de la unión al mismo, sino de las reacciones adversas o no, que pueda ocasionar sistémica o localmente. Desde el punto de vista biomecánico, su ductilidad y resistencia y su gran capacidad de autorreparación por el mecanismo de la pasivación inmediata anulando por tanto el fenómeno corrosivo, son sus mejores credenciales. Biológicamente, su compatibilidad con el medio que lo recibe permitiendo el crecimiento hístico a su alrededor sin interferirlo, junto a su baja o nula capacidad de reacción a cuerpo extraño y mucho menos en la producción de fenómenos de sensibilidad son las otras características que avalan su uso. Como material endoprotésico, junto a indudables constataciones clínicas y de laboratorio que le sitúan como el mejor metal proosteointegración, otras tratan de encontrar sombras para su empleo
Perencanaan dan Pembuatan Usaha Kebab Telor "Bablor Rame" (Tinjauan Aspek Pemasaran)"
This final project has a special pupose for knowing segmenting, targeting, positioning, marketing mix, obstacles and solutions to the in method project in its setup consists of a project preparation plan, and a project reporting plan. The result of this project is a geodefis outlook on Bengkalis region. Demgra rate of all kinds. A robust, fast food consumer caliphate. suggesting that all circles could consume this product. Lie a healthy fast food tray. The marketing kebab telor bablor Rame are wrapped in a paper wrap with a price that and talkers production and marketing cost and makes the price Rp. 8.000,- and the projects marketing site is promoted throught advertising and direct sales. the problem is the rain plungking weather and pandemic covid-19 which interfere with direct marketing and with product sticker logos not printed at the time of the market. Solution was a problem for intense promotion at sicial media and for immediate printing sticker logos product
SELEN 4 (SELEN version 4.0): a Fortran program for solving the gravitationally and topographically self-consistent sea-level equation in glacial isostatic adjustment modeling
Abstract. We present SELEN4 (SealEveL EquatioN solver), an open-source program written in
Fortran 90 that simulates the glacial isostatic adjustment (GIA) process in response
to the melting of the Late Pleistocene ice sheets. Using a pseudo-spectral approach complemented
by a spatial discretization on an icosahedron-based spherical geodesic grid, SELEN4 solves a
generalized sea-level equation (SLE) for a spherically symmetric Earth with linear viscoelastic
rheology, taking the migration of the shorelines and the rotational feedback on sea level into
account. The approach is gravitationally and topographically self-consistent, since it considers
the gravitational interactions between the solid Earth, the cryosphere, and the oceans, and
it accounts for the evolution of the Earth's topography in response to changes in sea level.
The SELEN4 program can be employed to study a broad range of geophysical effects of GIA,
including past relative sea-level variations induced by the melting of the Late Pleistocene ice
sheets, the time evolution of paleogeography and of the ocean function since the Last Glacial
Maximum, the history of the Earth's rotational variations, present-day geodetic signals observed
by Global Navigation Satellite Systems, and gravity field variations detected by satellite gravity
missions like GRACE (the Gravity Recovery and Climate Experiment). The "GIA fingerprints"
constitute a standard output of SELEN4. Along with the source code, we provide a supplementary
document with a full account of the theory, some numerical results obtained from a standard run,
and a user guide. Originally, the SELEN program was conceived by Giorgio Spada (GS) in 2005 as a tool for students eager
to learn about GIA, and it has been the first SLE solver made available to the
community
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