oalib

OALib Journal期刊

ISSN: 2333-9721

费用:99美元

投稿

时间不限

2017 ( 402 )

2016 ( 854 )

2015 ( 15213 )

2014 ( 19835 )

自定义范围…

匹配条件: “ Alexandrina Fül p” ,找到相关结果约461454条。
列表显示的所有文章,均可免费获取
第1页/共461454条
每页显示
Geochronology of the Neogene calc-alkaline intrusive magmatism in the "Subvolcanic Zone" of the Eastern Carpathians (Romania)
Zoltán Pécskay, Ioan Seghedi, Marinel Kovacs, Alexandru Szakács, , Alexandrina Fül p
Geologica Carpathica , 2009, DOI: 10.2478/v10096-009-0012-5
Abstract: The Poiana Botizei- ible -Toroiaga-Rodna-Bargau intrusive area (PBTTRB), northwest Romania, known as the "Subvolcanic Zone", is located between the Gutai (NW) and Calimani (SE) volcanic massifs. It consists of rocks displaying a wide range of compositions and textures: equigranular or porphyritic with holocrystalline groundmass (gabbro-diorites, diorites, monzodiorites and granodiorites), and/or porphyritic with fine holocrystalline or glassycryptocrystalline groundmass, similar with effusive rocks: basalts, basaltic andesites, andesites, dacites and rhyolites. The time-span of intrusive rocks emplacement is similar with the nearest calc-alkaline volcanic rocks from Gutai (NW) and Calimani (SE) massifs. They are represented by stocks, laccoliths, dykes and sills typical for an upper crustal intrusive environment. In the absence of biostratigraphic evidence, a comprehensive K-Ar study of intrusive rocks using whole rock samples, groundmass and monomineral fractions (biotite, hornblende) has been carried out in order to understand the magmatic evolution of the area. The oldest K-Ar ages recorded in the analysed rocks are close to 11.5 Ma and magmatism continued to develop until about 8.0 Ma. The inception of intrusion emplacement in the PBTTRB is coeval with intrusive activity spatially related to volcanism within the neighbouring Gutai and Calimani massifs. However, its culmination at ca. 8 Ma ago is younger than the interruption of this activity at ca. 9.2 Ma in Gutai and Calimani Mts where intrusive activity resumed for ca. 1 Myr. These circumstances strongly suggest that the geodynamic evolution of the area controlled the development of both volcanic and intrusive activity and their reciprocal relationships. The overall geological data suggest that in the PBTTRB intra-lithospheric transpressional-transtensional tectonic processes controlled the generation and emplacement of intrusive bodies between ca. 12-8 Ma.
On the age of the Dej Tuff, Transylvanian Basin (Romania)
Alexandru Szakács, , Zoltán Pécskay, Lóránd Silye, Kadosa Balogh, Daniela Vlad, Alexandrina Fül p
Geologica Carpathica , 2012, DOI: 10.2478/v10096-012-0011-9
Abstract: The Dej Tuff is an important stratigraphic marker in the Transylvanian Basin. However, its Early Badenian age is known only on biostratigraphical grounds so far. A number of radiometric dating techniques including K-Ar, Ar-Ar and fission-track have been used in order to constrain more precisely its age, allowing the calibration of the Transylvanian Basin's evolutionary models. Although individual dating methods could not provide a unique, reliable and accurate radiometric age, comparison and evaluation of multiple methods gives 14.8-15.1 Ma as the most likely formation age of the Dej Tuff.
Biomaterial Based on Doped Calcium Carbonate-Phosphate for Active Osteogenesis  [PDF]
Lyubov F. Koroleva, L. P. Larionov, N. P. Gorbunova
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2012, DOI: 10.4236/jbnb.2012.32028
Abstract: Doped calcium carbonate-phosphate is a biocompatible material that influence actively on the osteogenesis, bone regenerate, strengthening of bone and dental tissues including through the skin. A mechanism of the synthesis reactions of doped nanocrystalline calcium carbonate-phosphate an oscillating type of model for these reactions is proposed. The results indicate that the synthesis involves the formation of hydroxy carbonate complexes from the three calcium carbonate polymorphs (calcite, vaterite, and aragonite) in a solution of ammonium chloride and ammonium carbonate, followed by reaction with orthophosphoric acid. The formation of nanocrystalline calcium carbonate-phosphate doped with Fe2+, Mg2+, Zn2+, K+, Si4+, and Mn2+, has been studied by X-ray diffraction, IR spectroscopy, differential thermal analysis, and energy dispersive X-ray fluorescence analysis. This ensures the preparation of a bioactive material based on octacalcium hydrogen phosphate, and calcium chloride hydroxide phosphates containing cation vacancies. Particle-size analysis data show that the materials contain nanoparticles down to 10 nm in size. Heat treatment of the doped calcium carbonate phosphates produces calcium hydroxyapatite containing cation vacancies, which can be used as a bioactive ceramic.
Relativistic quantum mechanics on the SL(2,R) spacetime
T. Fülp
Physics , 1996, DOI: 10.1063/1.531885
Abstract: The Schr\"odinger-type formalism of the Klein-Gordon quantum mechanics is adapted for the case of the $SL(2,\R)$ spacetime. The free particle case is solved, the results of a recent work are reproduced while all the other, topologically nontrivial solutions and the antiparticle modes are also found, and a deeper insight into the physical content of the theory is given.
Structural Analysis and Static Simulation of Coastal Planktonic Networks  [PDF]
Gilberto C. Pereira, Lúcio P. Andrade, Rogério P. Espíndola, Nelson F. F. Ebecken
Journal of Intelligent Learning Systems and Applications (JILSA) , 2014, DOI: 10.4236/jilsa.2014.62009
Abstract:

The coastal marine habitats are often characterized by high biological activity. Therefore, monitoring programs and conservation plans of coastal environments are needed. So, in order to contribute to decision making process of the Brazilian Information System of Coastal Management, this paper presents a preliminary analysis of the effects of simulated deletions of individual organisms within a planktonic network as knowledge acquisition platform. An in situ scanning flow cytometer was used to data acquisition. A static and undirected food web is generated and represented by a fuzzy graph structure. Our results show through a series of indices the main changes of these networks. It was also verified similar traits and properties with other food webs found in the literature.

Sujeitos governados da EJA: reverbera es discursivas nas difíceis rela es entre saberes matemáticos
Alexandrina Monteiro,Jackeline Rodrigues Mendes,Maria Fátima Guimar?es
Reflex?o & A??o , 2012,
Abstract: Este artigo é fruto das discuss es realizadas pelo grupo de pesquisa em estudos de Foucault da Universidade S o Francisco. Alguns dos exemplos focalizados já foram temas de apresenta es em congressos nacionais e internacionais. Eles s o tomados como provoca es para algumas reflex es ancoradas em determinados episódios relacionados às aulas de matemática para alunos da Educa o de Jovens e Adultos (EJA). Nestas, muitas vezes, deparamo-nos com a cren a de que o uso de saberes mobilizados em práticas n o escolares, privilegiadamente daquelas práticas relacionadas às quest es financeiras ou de compra e venda, facilitaria a aprendizagem. A problematiza o proposta visa desconstruir a cren a do que entendemos ser uma tentativa de homogeneiza o em atividades escolares de práticas que, ao adentrarem na escola, se fortalecem ao serem legitimadas enquanto um discurso instituído disciplinarmente a partir de uma dada experiência docente que, muitas vezes, tende a desconsiderar as outras racionalidades trazidas pelos alunos. Para tanto, tomamos como mote de nossa discuss o alguns aspectos da legisla o que constituem o espa o normatizador da EJA, ou seja, o discurso de sua governamentalidade e, na sequencia, abordamos um episódio ocorrido em uma aula de matemática na EJA. Abstract Este artículo es el resultado de los debates del grupo de investigación en los estudios de Foucault de la Universidad en San Francisco. Algunos de los ejemplos que se han centrado fueran temas de presentaciones en conferencias nacionales e internacionales. Los ejemplos han tomado como provocación para algunos pensamientos anclados en ciertos episodios relacionados con las clases de matemáticas para estudiantes de la Educación de Jóvenes y Adultos (EJA). En estas clases, a menudo, nos dimos cuenta de la creencia de que el uso del conocimiento movilizados en prácticas no escolares, especialmente las prácticas relacionadas con asuntos financieros de compra y venta, pueden facilitar el aprendizaje. Lo debate aquí propuesto pretende deconstruir la creencia en lo que entendemos es un intento de homogeneización en las actividades escolares prácticas que, cuando se aventuran en la escuela, se fortalecen al ser legitimada como un discurso instituido por un procedimiento disciplinario a partir de una experiencia docente que, a menudo, tiende a no considerar otras racionalidades presentadas por los estudiantes. Así, tomamos como lema de nuestra discusión algunos aspectos de la legislación que constituyen el espacio normativo de EJA, es decir, el discurso de su gobernabilidad y, en la segunda parte
Evaluation of titanium dental implants after early failure of osseointegration by means of X-ray photoelectron spectoscopy, electron microscopy and histological studies  [PDF]
P. Lázaro, M. Herrero, F. J. Gil
Journal of Biomedical Science and Engineering (JBiSE) , 2010, DOI: 10.4236/jbise.2010.311139
Abstract: In this work, we analysed 56 clinically failed and retrieved implants by means of scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and histological studies. The surface contamination was compared to that of unused control implants and with that of the same implants after cleaning in a basic medium. The surfaces of the unused implants presented considerable contamination. In particular, high levels of carbon were detected. The nature of this C was elucidated by XPS analysis of the lubricant used in the machining process. The same contamination was observed in the retrieved implants. Histological studies were carried out by means of light microscopy. Fibrosis and granulomatous lesions were detected in the tissues. XPS analysis indicated the presence of traces of other elements (Na, Ca, Zn, S, F, etc.) that were not related to impurities in cpTi. We examined a cleaning process in a basic medium that eliminates the organic components of the implant surfaces. The cleaned implants were implanted in the patients and the results were excellent. None of the implants failed in following 7 months.
Want to Cure Cancer? Then Revisit the Past; “Warburg Was Correct”, Cancer Is a Metabolic Disease  [PDF]
Robert L. Elliott, Xian P. Jiang, Jonathan F. Head
Journal of Cancer Therapy (JCT) , 2014, DOI: 10.4236/jct.2014.53036
Abstract:

I want to make it very clear at the beginning of this communication; this is a controversial opinion review. However, I believe it is time to rethink our approach to cancer research and therapy. Many cancer researchers, especially those involved in cancer genomic research will disagree. I welcome the disagreement and hope it will stimulate an honest debate and dialog between all disciplines of cancer research and treatment. I am convinced that a vast disconnection exists between those involved in basic research and those in the clinical arena that treat this disease. Cancer researchers in all areas should not ignore the role of cancer metabolism in tumorigenesis, progression and metastasis.

New records of larval hostplants for ithomiinae butterflies (Nymphalidae)
COSTA, F. A. P. L.;
Revista Brasileira de Biologia , 1999, DOI: 10.1590/S0034-71081999000300010
Abstract: seventeen new records of larval hostplants are given for ithomiinae butterflies (lepidoptera: nymphalidae) in southeastern minas gerais, and one in brasília, df. at the present state of knowledge, generalizations about larval feeding habits of these insects may be premature.
Self-organized criticality in solar flares: a cellular automata approach
L. F. Morales,P. Charbonneau
Nonlinear Processes in Geophysics (NPG) , 2010,
Abstract: We give an overview of a novel lattice-based avalanche model that reproduces well a number of observed statistical properties of solar flares. The anisotropic lattice is defined as a network of vertically-connected nodes subjected to horizontal random displacements mimicking the kinks introduced by random motions of the photospheric footpoints of magnetic fieldlines forming a coronal loop. We focus here on asymmetrical driving displacements, which under our geometrical interpretation of the lattice correspond to a net direction of twist of the magnetic fieldlines about the loop axis. We show that a net vertical electrical current density does build up in our lattice, as one would expect from systematic twisting of a loop-like magnetic structure, and that the presence of this net current has a profound impact on avalanche dynamics. The presence of an additional energy reservoir tends to increase the mean energy released by avalanches, and yield a probability distribution of released energy in better agreement with observational inferences than in its absence. Symmetrical driving displacements are in better conceptual agreement with a random shuffling of photospheric footpoint, and yield a power-law distribution of energy release with exponent larger than 2, as required in Parker's nanoflare model of coronal heating. On the other hand, moderate asymmetrical driving generate energy distribution exponents that are similar to those obtained from SOHO EUV observations.
第1页/共461454条
每页显示


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.