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Search Results: 1 - 10 of 148353 matches for " K. Plaud-Ramos "
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Tests of cosmic ray radiography for power industry applications
J. M. Durham,E. Guardincerri,C. L. Morris,J. Bacon,J. Fabritius,S. Fellows,K. Plaud-Ramos,D. Poulson,J. Renshaw
Physics , 2015,
Abstract: In this report, we assess muon multiple scattering tomography as a non-destructive inspection technique in several typical areas of interest to the nuclear power industry, including monitoring concrete degradation, gate valve conditions, and pipe wall thickness. This work is motivated by the need for radiographic methods that do not require the licensing, training, and safety controls of x-rays, and by the need to be able to penetrate considerable overburden to examine internal details of components that are otherwise inaccessible, with minimum impact on industrial operations. In some scenarios, we find that muon tomography may be an attractive alternative to more typical measurements.
Silicon Encapsulated Carbon Nanotubes
Katar SriLakshmi,Labiosa AzlinBiaggi,Plaud Amairy,Mosquera-Vargas Edgar
Nanoscale Research Letters , 2009,
Abstract: A dual stage process of depositing bamboo-like carbon nanotubes (BCNTs) by hot filament chemical vapor deposition (HFCVD) and coating Si using Radio frequency sputtering (RFS) technique. The films were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electron field emission studies (EFE). SEM results suggest a dense network of homogeneous silicon-coated BCNTs. From the comprehensive analysis of the results provided by these techniques emerges the picture of Si encapsulated BCNTs.
Forma o para a docência universitária: uma reflex o sobre o desafio de humanizar a cultura científica
Carlinda Leite,Kátia Ramos
Revista Portuguesa de Educa??o , 2012,
Abstract: During the last years the pedagogical and didactical training of university teachers has become the focus of several institutions, a situation that was not common at this level of education. The importance of this aspect of teaching was present in the World Declaration on Higher Education (1998) and won more expression with the Bologna Declaration (1999). It is in the recognition that the training of university teachers must also pass by the pedagogicaldidactical component that some higher education institutions have been conducting training operations for updating, which constitute opportunities for reflection on teaching. This being the problem in this text, we feature in it challenges to teaching in this beginning of the XXI century and analyze an experience developed at the University of Porto, questioning the possibilities of these actions to configure spaces for dialogue between humanistic culture and scientific culture and contribute to a (re)contextualization of the know-how.
Mechanisms of Gene Duplication and Translocation and Progress towards Understanding Their Relative Contributions to Animal Genome Evolution
Olivia Mendivil Ramos,David E. K. Ferrier
International Journal of Evolutionary Biology , 2012, DOI: 10.1155/2012/846421
Abstract: Duplication of genetic material is clearly a major route to genetic change, with consequences for both evolution and disease. A variety of forms and mechanisms of duplication are recognised, operating across the scales of a few base pairs upto entire genomes. With the ever-increasing amounts of gene and genome sequence data that are becoming available, our understanding of the extent of duplication is greatly improving, both in terms of the scales of duplication events as well as their rates of occurrence. An accurate understanding of these processes is vital if we are to properly understand important events in evolution as well as mechanisms operating at the level of genome organisation. Here we will focus on duplication in animal genomes and how the duplicated sequences are distributed, with the aim of maintaining a focus on principles of evolution and organisation that are most directly applicable to the shaping of our own genome. 1. Introduction New genes constitute some of the major raw material for the evolution of biodiversity. They do not arise out of thin air. Some instances of new gene evolution from previously non-coding sequence have now been discovered [1, 2]. Also, new genes can be formed by shuffling of pre-existing nucleotide sequences. The relatively recent discovery of large numbers of taxonomically restricted genes also demands a closer investigation of their mode(s) of origin [3]. Nevertheless, a major mechanism for the generation of new genes is via duplication. Such duplicates are called paralogues, to reflect their homologous relationship being due to a duplication event rather than a speciation event (see Figure 1). Figure 1: Overview of the current terminology. The different panels represent term(s) for duplicated genes. (a) Orthologues. The square blue arrows represent an orthologous relationship between the two genes. (b) Paralogues. The square green arrows represent paralogous relationships between the genes. (c) Proto-orthologue. The square red arrow represents the pro-orthologue relationship of gene a/b from Branchiostoma floridae to gene a from Mus musculus. (d) Semi-orthologue. The square orange arrow represents the semi-orthologous relationship of gene a of Mus musculus to gene a/b from Branchiostoma floridae. (e) Inparalogues and Outparalogues. The square yellow arrows represent the outparalogous relationship in which human and mouse a genes are outparalogous to human and mouse b genes. As a set, genes a and b from mouse and human represents coorthologues. The square purple arrows represent the inparalogous relationship
A Comparison of Spatial Interpolation Methods for Estimation of Average Electromagnetic Field Magnitude
Marco A. Azpurua;K. Dos Ramos
PIER M , 2010, DOI: 10.2528/PIERM10083103
Abstract: Several georeferenced measurements of electric field were done in a pilot area of Caracas, Venezuela, to verify that the magnitude of radio frequency electromagnetic fields is below the human exposure limits, recommended by the International Commission on Non-Ionizing Radiation Protection. The collected data were analyzed using geographical information systems, with the objective of using interpolation techniques to estimate the average electromagnetic field magnitude, to obtain a continuous dataset that could be represented over a map of the entire pilot area. This paper reviews the three methods of interpolation used: SPLINE, Inverse Distance Weighting (IDW) and KRIGING. A statistical assessment of the resultant continuous surfaces indicates that there is substantial difference between the estimating ability of the three interpolation methods and IDW performing better overall.
Cryopreservation of Cat’s Claw (Uncaria tomentosa)  [PDF]
J. Perez, A. Guillen, K. Ramos, F. Engelmann, A. Abdelnour-Esquivel
American Journal of Plant Sciences (AJPS) , 2015, DOI: 10.4236/ajps.2015.618291
Abstract: Uncaria tomentosa presents tomentum that resembles cat’s claws, hence its common name, is a plant that produces various secondary metabolites that are traditionally used in alternative medicine. The natural distribution of this species has been affected by indiscriminate harvesting from its habitat. In the present research, cryopreservation (liquid nitrogen, LN, -196°C) was evaluated as an option for ex situ conservation of this species. The following techniques were evaluated: vitrification and encapsulation-dehydration of apices, vitrification of cell suspensions, and seed desiccation and vitrification. Preculture conditions and exposure times to LS and PVS2 were evaluated. Apex survival was the highest (82%) with preculture in 0.25 M sucrose followed by incubation for 20 and 30 min in LS and PVS2, respectively, prior to cooling in LN. The encapsulation-dehydration technique was evaluated by using sucrose preculture and different capsule moisture contents. Survival of apices cooled in LN was not significantly different between treatments and varied from 31.8% to 52.9% for capsule moisture contents between 22.7% and 20.3%. For cell suspensions precultured in 0.5 M sucrose, cell multiplication and formation of calli with very good appearance were observed in 61.1% of the cultures following vitrification. For cryopreservation of seeds, germination was 89.5% using the desiccation technique and 67.6% to78.1% using vitrification.
Evidence for two Lambda(1405) resonance states
E. Oset,V. K. Magas,A. Ramos
Physics , 2005, DOI: 10.1063/1.2176491
Abstract: The $K^- p \to \pi^0 \pi^0 \Sigma^0$ reaction is studied within a chiral unitary model. The distribution of $\pi^0 \Sigma^0$ states forming the $\Lambda(1405)$ shows, in agreement with a recent experiment, a peak at 1420 MeV and a relatively narrow width of $\Gamma = 38$ MeV. We use these data in combination with those of the $\pi^- p \to K^0 \pi \Sigma$ reaction and elements of chiral unitary theory to prove that there are two $\Lambda(1405)$ states instead of one as so far assumed.
The Pt isotopes: comparing the Interacting Boson Model with Configuration Mixing and the Extended Consistent-Q formalism
J. E. Garcia-Ramos,K. Heyde
Physics , 2009, DOI: 10.1016/j.nuclphysa.2009.04.003
Abstract: The role of intruder configurations in the description of energy spectra and B(E2) values in the Pt region is analyzed. In particular, we study the differences between Interacting Boson Model calculations with or without the inclusion of intruder states in the even Pt nuclei $^{172-194}$Pt. As a result, it shows that for the description of a subset of the existing experimental data, i.e., energy spectra and absolute B(E2) values up to an excitation energy of about 1.5 MeV, both approaches seem to be equally valid. We explain these similarities between both model spaces through an appropriate mapping. We point out the need for a more extensive comparison, encompassing a data set as broad (and complete) as possible to confront with both theoretical approaches in order to test the detailed structure of the nuclear wave functions.
Critical review of [K- ppn] bound states
V. K. Magas,E. Oset,A. Ramos
Physics , 2008, DOI: 10.1103/PhysRevC.77.065210
Abstract: We make a thorough study of the process of three body kaon absorption in nuclei, in connection with a recent FINUDA experiment which claims the existence of a deeply bound kaonic state from the observation of a peak in the Lambda d invariant mass distribution following K- absorption on Li6. We show that the peak is naturally explained in terms of K- absorption from three nucleons leaving the rest as spectators. We can also reproduce all the other observables measured in the same experiment and used to support the hypothesis of the deeply bound kaon state. Our study also reveals interesting aspects of kaon absorption in nuclei, a process that must be understood in order to make progress in the search for K- deeply bound states in nuclei.
Avalanche prediction in Self-organized systems
O. Ramos,E. Altshuler,K. J. Maloy
Physics , 2008, DOI: 10.1103/PhysRevLett.102.078701
Abstract: It is a common belief that power-law distributed avalanches are inherently unpredictable. This idea affects phenomena as diverse as evolution, earthquakes, superconducting vortices, stock markets, etc; from atomic to social scales. It mainly comes from the concept of ``Self-organized criticality" (SOC), where criticality is interpreted in the way that at any moment, any small avalanche can eventually cascade into a large event. Nevertheless, this work demonstrates experimentally the possibility of avalanche prediction in the classical paradigm of SOC: a sandpile. By knowing the position of every grain in a two-dimensional pile, avalanches of moving grains follow a distinct power-law distribution. Large avalanches, although uncorrelated, are preceded by continuous, detectable variations in the internal structure of the pile that are monitored in order to achieve prediction.
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