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Search Results: 1 - 10 of 4374 matches for " Medina "
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Coulomb Stress Perturbations Related to the Al Hoceima (Morocco) Earthquakes of 1994 and 2004  [PDF]
Fida Medina
Open Journal of Earthquake Research (OJER) , 2015, DOI: 10.4236/ojer.2015.41004
Abstract: This paper exposes the results of the study of the stress perturbations caused by the Al Hoceima (Morocco) earthquakes of 1994 and 2004 by means of Coulomb modeling. Modeling was based on the compilation of all the studies carried out after both events, including seismological (location and depth of the main shocks and aftershocks), seismotectonic (source parameters, stress field), geodetic (GPS), tomographic and geological ones. It shows that the first earthquake is likely to have induced the second one when adopting appropriate epicenter locations, source and receiver fault planes. In detail, the model shows that motion along the N23E oriented Bousekkour-Aghbal fault in 1994 activated the eastern segment of a previously unknown NW-SE fault located at its southern end, which in turn originated the 2004 earthquake. The model also provides a suitable explanation for the distribution of the aftershock clusters. Finally, an attempt of prediction of the next event shows that it is likely to occur on NE-SW planes located to the NW (Bokkoya and offshore) and SE (reaching the Nekor fault) of the NW-SE fault, while Al Hoceima city should remain in a shadow zone.
Cost Analysis of Diffusion Tensor Imaging and MR Tractography of the Brain  [PDF]
Christopher Hancock, Byron Bernal, Camila Medina, Santiago Medina
Open Journal of Radiology (OJRad) , 2014, DOI: 10.4236/ojrad.2014.43034
Abstract: Purpose: To determine the total direct costs (fixed and variable costs) of diffusion tensor imaging (DTI) and MR tractography reconstruction of the brain. Materials and Methods: The direct fixed and variable costs of DTI with MR tractography were determined prospectively with time and motion analysis in a 1.5-Tesla MR scanner using 15 encoding directions. Seventeen patients with seizure disorders, 9 males & 8 females, with mean age of 13 years (age range 2 - 33 years) were studied. Total direct costs were calculated from all direct fixed and variable costs. Sensitivity analyses between 1.5 versus a 3-Tesla MR system, and 15 versus 32 encoding directions were done. Results: The total direct costs of DTI and MR tractography for a 1.5-T system with 15 encoding directions were US $97. Variable cost was $76.80 and fixed cost was $20.20. Total direct costs for a 3-T system with 15 directions decreased to US $94.5 because of the shorter scan time despite the higher cost of the 3-T system. The most costly component of the direct cost was post-processing analysis at US $46.00. Conclusion: DTI with MR tractography has important total direct costs with variable costs higher than the fixed costs. The post processing variable cost is the most expensive component. Developing more accurate automated post-processing software for DTI and MR tractography is important to decrease this variable labor cost. Given the added value of DTI-MR tractography and the costs involved reimbursement codes should be considered.
On the Relationship between the Pure Delay and the Natural Period of Oscillation  [PDF]
Daniel Chuk, Gustavo Rodriguez Medina
Applied Mathematics (AM) , 2016, DOI: 10.4236/am.2016.76046
Abstract: This paper provides a proof of the well-known relationship between the pure delay and the natural period of oscillation in industrial systems.
Accurate solution estimates for vector difference equations
Rigoberto Medina
International Journal of Mathematics and Mathematical Sciences , 2003, DOI: 10.1155/s016117120321022x
Abstract: Accurate estimates for the norms of the solutions of a vector difference equation are derived. They give us stability conditions and bounds for the region of attraction of the stationary solution. Our approach is based on estimates for the powers of a constant matrix. We also discuss applications of our main results to partial reaction-diffusion difference equations and to a Volterra difference equation.
Estimates for the norms of solutions of delay difference systems
Rigoberto Medina
International Journal of Mathematics and Mathematical Sciences , 2002, DOI: 10.1155/s0161171202013017
Abstract: We derive explicit stability conditions for delay difference equations in ℂn (the set of n complex vectors) and estimates for the size of the solutions are derived. Applications to partial difference equations, which model diffusion and reaction processes, are given.
Estimates for the norms of solutions of difference systems with several delays
Rigoberto Medina
International Journal of Mathematics and Mathematical Sciences , 2004, DOI: 10.1155/s016117120430801x
Abstract: We derive explicit stability conditions for time-dependent difference equations with several delays in Cn (the set of n complex vectors) and estimates for the size of the solutions. The growth rates obtained here are not necessarily decay rates.
Ocupa??o cabocla e extrativismo madeireiro no alto capim: uma estratégia de reprodu??o camponesa
Medina, Gabriel;
Acta Amazonica , 2004, DOI: 10.1590/S0044-59672004000200017
Abstract: as the timber industry advances throughout the amazon basin, communities located along logging frontiers are increasingly approached to sell the rights to their timber. such communities consider several aspects to assess the value of forest products. locally perceived value and behaviors towards tropical forest resources contrast sharply with globally constructed views of tropical forest value. this locally perceived value is based on representations regarding the importance of forest products and on the context in which these representations are formed. to explore this theme, the paper begins with a historical reconstruction of a caboclo community focusing on forest resource use and dynamics during the last hundred years. for the households within the study communities, timber always represented a natural heritage that could be spent over time. it was the principal product with market value and, during initial timber sales, extraction did not significantly reduce access to other forest products. therefore, timber resources represented an inheritance with exchange value and little conflicting use. four socioeconomic factors were identified which influenced communities to sell timber despite the losses in non-timber forest products that they began to experience over time: 1) paternalistic relationships among buyers and caboclos; 2) difficulties in common property resource management; 3) quick cash gained from timber sales guaranteed access to market products and; 4) expanding market involvement required increased cash to meet increasing needs.
Prevalencia de maloclusiones dentales en un grupo de pacientes pediátricos
Medina,Carolina;
Acta Odontológica Venezolana , 2010,
Abstract: objective: to determine the prevalence of dental malocclusion presented by pediatric patients treated at the interceptive orthodontics clinic, pediatric dentistry postgraduate program, ucv. materials and methods: orthodontic diagnostic records of 479 patients were used. classification was made based on angle?s criteria, using dewey-anderson?s modifications. results: 64.30% of the simple presented with class i malocclusion, 20.67% with class ii and 15.03% with class iii. 97,29 % of the patients were ages 5 to 12, being mean age 8 years old at evaluation. frequency of boys (52,82%) was slightly higher than girls (47,18 %). conclusion: class i maloclusión was most frequent, followed by class ii and class iii. the prevalence of each malocclusion differs from other studies due to methodological variations in the selection and classification of patients and characteristics inherent to this particular group
Tradición poética y mito en la poesía de Elí Galindo
Medina,Celso;
Letras , 2009,
Abstract: we attempt an in-depth look into the poetry of eli galindo, with the poetic tradition and myth as reading guidelines. as he continues a poetic trend started in venezuela by josé antonio ramos sucre, and further worked by francisco pérez perdomo, galindo builds up a work that creates a poetic mood on the basis of great archetypes, whose fundamental intertext is dante?s devine comedy. masks and polyphony are essential strategies in a poetics that, despite its little prolixity, stands as a valuable landmark in venezuelan poetry. that mythical plinth that supports the work of eli galindo reflects a suis generis philosophy, that hands the readers a vision of the world where existentialist issues, such as death and solitude, weave themselves into a quite original thought in our poetry. for the research we intend here, we will use his book san baudelaire, which comprises the very short, but dense, poetic work of eli galindo. we will carry out this exploration on the basis of phenomenology, in the very particular view of gastón bachelard, for whom the materiality of the poetic incarnates not in the metaphoric world but in an imaginary of things in its most naked reality. we start from the hypothesis that what galindo?s poetry says is what it shows at first; form that we device our analysis, from there we configure a cosmologic philosophy that accounts for the poetic ontology of this venezuelan writer.
INTRAHISTORIA, COTIDIANIDAD Y LOCALIDAD
MEDINA,CELSO;
Atenea (Concepción) , 2009, DOI: 10.4067/S0718-04622009000200009
Abstract: in this article, we place in discussion the polemical concept of intra-history, introduced by the spanish philosopher miguel de unamuno in his book en torno al casticismo, edited in 1895. our objective is to correlate it to the vision of history developed in the 20th century called micro-history, whose principal ideologue was the italian carlo ginzburg. we begin with the following premise: unamuno’s intra-history views history from a minimalist version of social events, which helps us to link his concept to the study of the everyday and the local. for unamuno, history should be interested in the routes whose principle leading roles are played by its peripheral actors; that is to say, the paths followed by those men who make history in an unconscious manner, by those who do not aspire to the title of heroes. and so the writer places his bets on the "living tradition", the paradoxical tradition of the present. furthermore, we can observe in these ideas of unamuno a rejection of tragic history which is woven through the force of intrigues. where do unamuno’s and ginzburg’s thought meet? we believe that they coincide in the reduction in scale of the study of history. the historical event is not the monumental fresco that encourages the mythification of politicians, military men and priests, the traditional heroes of history; it is more precisely demotic in the sense understood by the spaniard, or in the study of "the cultures of the subaltern classes", according to the vision of the italian. correlating the ideas of both writers can be a productive path in understanding the complexity of local culture in light of the latin american cultural climate.
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