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Search Results: 1 - 10 of 45483 matches for " Marco Antonio; "
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Sex-biased expression of microRNAs in Drosophila melanogaster
Antonio Marco
Quantitative Biology , 2013, DOI: 10.1098/rsob.140024
Abstract: Most animals have separate sexes. The differential expression of gene products, in particular that of gene regulators, is underlying sexual dimorphism. Analyses of sex-biased expression have focused mostly in protein coding genes. Several lines of evidence indicate that microRNAs, a class of major gene regulators, are likely to have a significant role in sexual dimorphism. This role has not been systematically explored so far. Here I study the sex-biased expression pattern of microRNAs in the model species Drosophila melanogaster. As with protein coding genes, sex biased microRNAs are associated with the reproductive function. Strikingly, contrary to protein-coding genes, male biased microRNAs are enriched in the X chromosome whilst female microRNAs are mostly autosomal. I propose that the chromosomal distribution is a consequence of high rates of de novo emergence, and a preference of new microRNAs to be expressed in the testis. I also suggest that demasculinization of the X chromosome may not affect microRNAs. Interestingly, female biased microRNAs are often encoded within protein coding genes that are also expressed in females. MicroRNAs with sex-biased expression do not preferentially target sex-biased gene transcripts. These results strongly suggest that the sex-biased expression of microRNAs is mainly a consequence of high rates of microRNA emergence in the X (male bias) or hitch-hiked expression by host genes (female bias).
Finite Elements Based on Deslauriers-Dubuc Wavelets for Wave Propagation Problems  [PDF]
Rodrigo Bird Burgos, Marco Antonio Cetale Santos
Applied Mathematics (AM) , 2016, DOI: 10.4236/am.2016.714128
Abstract: This paper presents the formulation of finite elements based on Deslauriers-Dubuc interpolating scaling functions, also known as Interpolets, for their use in wave propagation modeling. Unlike other wavelet families like Daubechies, Interpolets possess rational filter coefficients, are smooth, symmetric and therefore more suitable for use in numerical methods. Expressions for stiffness and mass matrices are developed based on connection coefficients, which are inner products of basis functions and their derivatives. An example in 1-D was formulated using Central Difference and Newmark schemes for time differentiation. Encouraging results were obtained even for large time steps. Results obtained in 2-D are compared with the standard Finite Difference Method for validation.
Comercializa??o no ensino superior: é possível manter a idéia de bem público?
Dias, Marco Antonio Rodrigues;
Educa??o & Sociedade , 2003, DOI: 10.1590/S0101-73302003000300005
Abstract: one of the promoters of the brazilian debate on the impact on education of the measures taken by the wto, the author wonders whether we can still maintain the idea that higher education is a public good, as advocated by the world conference on higher education in paris, 1998. the academic community lost the opportunity to react efficiently when, in 1994, the general agreement on trade in services (gats) was signed. yet, private providers are not enough to make a service commercial. although the basic principles protecting the public goods are maintained under regulation, the figures of concession, delegation and authorization persist. within the wto, the anglo-saxon countries act inconsistently, closing the very doors they ask the others to open. the bigger danger, nowadays, is an attempt to create an international accreditation system, without the participation of latin america
Dez anos de antagonismo nas políticas sobre ensino superior em nível internacional
Dias, Marco Antonio Rodrigues;
Educa??o & Sociedade , 2004, DOI: 10.1590/S0101-73302004000300012
Abstract: ex-vice-director of and retired professor from the unb, the author was, for over 17 years (1981-1999), the director of the unesco higher education division. he thus supervised the elaboration of the unesco higher education policy documents and coordinated the organization of this organization's world conference on higher education, in 1998. he considers that there is no neutrality in that matter, most particularly in his case, because of the responsibilities he assumed during almost two decades at unesco. he remembers that, ten years ago, two documents concerning higher education policies were issued at the international level by the world bank and by the unesco. both were based on similar diagnoses, but came to totally diverse conclusions, since they were the produce of radically different visions of society. one side considered higher education as a tool to consolidate the market, while the other saw it as a collective entity that should be taken into account according to its cultural and social specificities. nowadays, with the interference of new actors, such as the wto for example, the officials from these two organizations are getting closer in their positions, and one cannot predict which thrust the academic community and the states members of these organizations will adopt in the future.
Phage display technology: applications and innovations
Arap, Marco Antonio;
Genetics and Molecular Biology , 2005, DOI: 10.1590/S1415-47572005000100001
Abstract: the expression of exogenous peptides on the surface of filamentous bacteriophage was initially described by smith in 1985. since his first study, different molecules such as small peptides and antibodies have been displayed on coat proteins of phage, greatly expanding the applications of the technology. the past decade has seen considerable progress in the techniques and applications of phage libraries. in addition, different screening methods have allowed isolation and characterization of peptides binding to several molecules in vitro, in the context of living cells, in animals and in humans. here we review the applications, recent innovations, and future directions of phage display technology.
A ama-de-leite e o bebê: reflex?es em torno do apagamento de uma face
Stancik, Marco Antonio;
História (S?o Paulo) , 2009, DOI: 10.1590/S0101-90742009000200023
Abstract: the objective of this short essay is to analyses a portrait of the late of xixth century. the portrait presents a wet nurse and a baby. it is believed that the picture may show the inequality and contradictions of social relations in the brazilian society, and exemplify the use of photographic sources in the historical researches.
O imaginário sobre o militar em cart?es-postais franceses (1900-1918)
Stancik, Marco Antonio;
História (S?o Paulo) , 2012, DOI: 10.1590/S0101-90742012000100007
Abstract: after the shameful defeat in the franco-prussian war (1870) and the seizure of alsace and lorraine, france fueled the desire for revenge against germany. in this context, the paper analyzes visual representations concerning alsace-lorraine and the french and german military, as transmitted by postcards produced and circulated in france on the eve and during of world war i (1914-1918). was observed the use of sentimental, nationalistic and bellicose images, in tune with the collective anti-german imaginary.
Hospício de doutores
Arantes, Marco Antonio;
História, Ciências, Saúde-Manguinhos , 2008, DOI: 10.1590/S0104-59702008000100004
Abstract: an impassioned writer, suburbano, black, daring, ironic, combative, accursed, and misunderstood by his contemporaries, afonso henriques de lima barreto (1881-1922) traveled to hell, experiencing the scorn of critics, failure as a writer, and his family's indifference towards his literary vocation. restless in his pain and heavy-handed with hypocrites, he grappled with the tragedies of madness, alcoholism, and prejudice at a time when assuming one's condition as a black was an act of courage. his conscious observations about doctors, the mad, and madness is the point of departure for this study, based on the writer's experience at the hospício nacional and on a review of significant excerpts from lima barreto's literary production. the latter stands as an institutional and political issue and a criticism of the discourses that played important roles in preserving the structures of domination in the old republic.
A circula??o do sangue, ou o movimento no conceito de movimento
Porto, Marco Antonio T.;
História, Ciências, Saúde-Manguinhos , 1994, DOI: 10.1590/S0104-59701994000100004
Abstract: the contemporary medical practice is enrolled in the rigid principles of a technological order. in order that the development and organization of the technological order would take place, and also material and objetively made concrete, it was essential that their products represented a materialization of a certain concept of human body and of health. this paper intends to be an introductory study of certain conditions of possibility for the construction of this technological order in the area of health. although this thought includes, necessarily, a historical dimension, we do not intend here a factual reconstitution that considers dates and personalities. its immediate goal will be to focus a moment of rupture, in which the introduction of the new concept of motion generated a new conception of human physiology. so, more important than one specific theory - of the blood circulation - or its effective results, is to understand the process of arising and/or changing of the concepts that allowed it to exist originally.
The nature of the chemical bond
Nascimento, Marco Antonio Chaer;
Journal of the Brazilian Chemical Society , 2008, DOI: 10.1590/S0103-50532008000200007
Abstract: in this paper we briefly review the basic requirements that must be satisfied by any wave function representing many-electron systems. following that, we examine the conditions under which the classical concepts of molecular structure, chemical structure and chemical bond can be translated into a quantum-mechanical language. essential to this aim is the utilization of an independent particle model (ipm) for a many-electron system. in spite of the great popularity of the hartree-fock (hf) model only valence-bond (vb) type wave functions with optimized, singly occupied and non necessarily orthogonal atomic-like orbitals, can provide a quantum-mechanical translation of the classical concepts of chemical structure and chemical bond, although the hf model can still be useful for translating the concept of molecular structure. finally, a quantum-dynamical-type of analysis allows us to conclude that, from the quantum mechanical point of view, the chemical bond is a consequence of interference effects. from the energetic point of view, the interference effect responsible for the bond formation manifests itself as a reduction of the kinetic energy of the electrons as the bond is formed.
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