Showing papers by "Universidade Federal de Minas Gerais published in 2002"
01 Jun 2002
TL;DR: A taxonomy for characterizing Web data extraction fools is proposed, a survey of major web data extraction tools described in the literature is briefly surveyed, and a qualitative analysis of them is provided.
Abstract: In the last few years, several works in the literature have addressed the problem of data extraction from Web pages. The importance of this problem derives from the fact that, once extracted, the data can be handled in a way similar to instances of a traditional database. The approaches proposed in the literature to address the problem of Web data extraction use techniques borrowed from areas such as natural language processing, languages and grammars, machine learning, information retrieval, databases, and ontologies. As a consequence, they present very distinct features and capabilities which make a direct comparison difficult to be done. In this paper, we propose a taxonomy for characterizing Web data extraction fools, briefly survey major Web data extraction tools described in the literature, and provide a qualitative analysis of them. Hopefully, this work will stimulate other studies aimed at a more comprehensive analysis of data extraction approaches and tools for Web data.
760 citations
TL;DR: In this article, a simple model of the incentives to commit crimes is proposed, which explicitly considers possible causes of the persistence of crime over time (criminal inertia), and a panel-data based GMM methodology is used to estimate a dynamic model of national crime rates.
654 citations
TL;DR: In this article, a cellular automata model called dinamica is used to simulate spatial patterns of land-use and land-cover changes produced by the Amazonian colonists in clearing the forest, cultivating the land and eventually abandoning it for vegetation succession.
536 citations
TL;DR: In this paper, G-band resonance Raman spectra of single-wall carbon nanotubes (SWNTs) at the singlenanotube level have been reported and conclusively determined the dependence of the two most intense features on the nanotube structure.
Abstract: We report G-band resonance Raman spectra of single-wall carbon nanotubes ~SWNTs! at the singlenanotube level. By measuring 62 different isolated SWNTs resonant with the incident laser, and having diameters dt ranging between 0.95 nm and 2.62 nm, we have conclusively determined the dependence of the two most intense G-band features on the nanotube structure. The higher-frequency peak is not diameter dependent (v G 51591 cm 21 ), while the lower-frequency peak is given by v G 5v G 2C/dt , with C being different for metallic and semiconducting SWNTs (CM.CS). The peak frequencies do not depend on nanotube chiral angle. The intensity ratio between the two most intense features is in the range 0.1 ,I v G /I v G,0.3 for most of the isolated SWNTs (;90%). Unusually high or low Iv G /I v G ratios are observed for a few spectra coming from SWNTs under special resonance conditions, i.e., SWNTs for which the incident photons are in resonance with the E44 interband transition and scattered photons are in resonance with E33 . Since the Eii values depend sensitively on both nanotube diameter and chirality, the ( n,m) SWNTs that should exhibit such a special G-band spectra can be predicted by resonance Raman theory. The agreement between theoretical predictions and experimental observations about these special G-band phenomena gives additional support for the (n,m) assignment from resonance Raman spectroscopy.
485 citations
TL;DR: In this paper, the adsorption features of activated carbon and the magnetic properties of iron oxides were combined in a composite to produce magnetic adsorbents, which can be used as adsorbent for a wide range of contaminants in water and can subsequently be removed from the medium by simple magnetic procedure.
477 citations
TL;DR: The data indicate that a poorly modulated T-cell response in mucosal leishmaniasis patients leads to production of high levels of proinflammatory cytokines, such as IFN-γ and TNF-α, as well as a decreased ability of IL-10 and TGF-β to modulate this response.
Abstract: The cytokine profile produced by peripheral blood mononuclear cells (PBMC) in response to leishmania antigens and the ability of interleukin-10 (IL-10) and transforming growth factor β (TGF-β) to modulate the immune response were evaluated in 21 mucosal leishmaniasis patients. Patients with mucosal disease exhibited increased gamma interferon (IFN-γ) and tumor necrosis factor alpha (TNF-α) secretion and decreased IL-10 secretion compared to patients with classical cutaneous leishmaniasis. CD4+ Th1 cells were the main source of IFN-γ and TNF-α production in mucosal leishmaniasis patients. Evaluation of cytokine gene expression in PBMC of these patients showed that there was strong up-regulation of IFN-γ transcripts upon stimulation with leishmania antigen, in contrast to the baseline levels of IL-10 mRNA. IL-10 suppressed IFN-γ production by 48% in cell cultures from cutaneous leishmaniasis patients and by 86% in cell cultures from healthy subjects stimulated with purified protein derivative, whereas in similar conditions IL-10 suppressed IFN-γ production by 19% in cell cultures from mucosal leishmaniasis patients stimulated with leishmania antigen. TGF-β suppressed IFN-γ levels to a greater extent in healthy subjects than in mucosal leishmaniasis and cutaneous leishmaniasis patients. These data indicate that a poorly modulated T-cell response in mucosal leishmaniasis patients leads to production of high levels of proinflammatory cytokines, such as IFN-γ and TNF-α, as well as a decreased ability of IL-10 and TGF-β to modulate this response. These abnormalities may be the basis for the pathological findings observed in this disease.
315 citations
TL;DR: In this article, the authors presented an investigation of the cure rate of specific chemotherapy with benznidazole in patients with both acute and chronic Chagas disease, applying quantitative conventional serological tests as the base of the criterion of cure.
Abstract: The aim of this article is to present an investigation of cure rate, after long follow up, of specific chemotherapy with benznidazole in patients with both acute and chronic Chagas disease, applying quantitative conventional serological tests as the base of the criterion of cure. Twenty one patients with the acute form and 113 with one or other of the various chronic clinical forms of the disease were evaluated, after a follow up period of 13 to 21 years, for the acute, and 6 to 18 years, for the chronic patients. The duration of the acute as well as the chronic disease, a condition which influences the results of the treatment, was determined. The therapeutic schedule was presented, with emphasis on the correlation between adverse reactions and the total dose of 18 grams, approximately, as well as taking into consideration precautions to assure the safety of the treatment. Quantitative serological reactions consisting of complement fixation, indirect immunofluorescence, indirect hemagglutination, and, occasionally, ELISA, were used. Cure was found in 76 per cent of the acute patients but only in 8 per cent of those with chronic forms of the disease. In the light of such contrasting results, fundamentals of the etiological therapy of Chagas disease were discussed, like the criterion of cure, the pathogenesis and the role of immunosuppression showing tissue parasitism in long standing chronic disease, in support of the concept that post-therapeutic consistently positive serological reactions mean the presence of the parasite in the patient's tissues. In relation to the life-cycle of T. cruzi in vertebrate host, there are still some obscure and controversial points, though there is no proof of the existence of resistant or latent forms. However, the finding over the last 15 years, that immunosuppression brings about the reappearance of acute disease in long stand chronic patients justifies a revision of the matter. Facts were quoted in favor of the treatment of chronic patients.
287 citations
TL;DR: In this article, a quantum eraser experiment using a Young double slit to create interference was reported. But the experiment was performed under ''delayed erasure'' circumstances, which is not the case in this paper.
Abstract: We report a quantum eraser experiment which actually uses a Young double slit to create interference. The experiment can be considered an optical analogy of an experiment proposed by Scully, Englert, and Walther [Nature (London) 351, 111 (1991)]. One photon of an entangled pair is incident on a Young double slit of appropriate dimensions to create an interference pattern in a distant detection region. Quarter-wave plates, oriented so that their fast axes are orthogonal, are placed in front of each slit to serve as which-path markers. The quarter-wave plates mark the polarization of the interfering photon and thus destroy the interference pattern. To recover interference, we measure the polarization of the other entangled photon. In addition, we perform the experiment under ``delayed erasure'' circumstances.
286 citations
University of South Florida1, University of Manchester2, Florida International University3, University of Waikato4, Massey University5, Kaohsiung Medical University6, University of the Witwatersrand7, Universidade Federal de Minas Gerais8, University of Ljubljana9, Babeș-Bolyai University10, University of Navarra11, University of Texas at El Paso12, Bulgarian Academy of Sciences13, University of Santiago, Chile14, Tokyo Keizai University15, Lingnan University16, Ghent University17, Tel Aviv University18, Trinity Western University19, Nofer Institute of Occupational Medicine20
TL;DR: Managers from 24 geopolitical entities provided data on work locus of control, job satisfaction, psychological strain, physical strain, and individualism/collectivism, with the hypothesis that the salut...
Abstract: Managers from 24 geopolitical entities provided data on work locus of control, job satisfaction, psychological strain, physical strain, and individualism/collectivism. The hypothesis that the salut...
282 citations
06 Nov 2002
TL;DR: A thorough characterization of what is believed to be the first significant live Internet streaming media workload in the scientific literature is presented, and a model for live media workload generation is presented that incorporates many of the findings, and which is implemented in GISMO.
Abstract: We present what we believe to be the first thorough characterization of live streaming media content delivered over the Internet. Our characterization of over 3.5 million requests spanning a 28-day period is done at three increasingly granular levels, corresponding to clients, sessions, and transfers. Our findings support two important conclusions. First, we show that the nature of interactions between users and objects is fundamentally different for live versus stored objects. Access to stored objects is user driven, whereas access to live objects is object driven. This reversal of active/passive roles of users and objects leads to interesting dualities. For instance, our analysis underscores a Zipf-like profile for user interest in a given object, which Is in contrast to the classic Zipf-like popularity of objects for a given user. Also, our analysis reveals that transfer lengths are highly variable and that this variability is due to the stickiness of clients to a particular live object, as opposed to structural (size) properties of objects. Second, by contrasting two live streaming workloads from two radically different applications, we conjecture that some characteristics of live media access workloads are likely to be highly dependent on the nature of the live content being accessed. In our study, this dependence is clear from the strong temporal correlations observed in the traces, which we attribute to the synchronizing impact of live content on access characteristics. Based on our analyses, we present a model for live media workload generation that incorporates many of our findings, and which we implement in Gismo [19].
269 citations
TL;DR: This paper focuses on the development of a system that takes speech acoustics as input, and gives as output the coefficients necessary to animate natural face and head motion.
TL;DR: This paper argued that different kinds of lit- eracy have resulted from different modalities of written communi- cation, and that literacy is not a single, homogeneous phenomenon.
Abstract: In the context of two different cultures - print cul- ture and electronic culture, or cyberculture -, this article seeks a clearer comprehension of literacy opposing typographic and digi- tal technologies of reading and writing. Through the differences regarding the writing space and the mechanisms of producing, re- producing and diffusing ideas, it argues that different kinds of lit- eracy - that is, different social, cognitive and discursive effects - have resulted from such different modalities of written communi- cation. Since literacy is not a single, homogeneous phenomenon, it finally suggests this word should be used in its plural rather than singular form: literacies.
TL;DR: In this paper, the phase behavior of linear poly(N-isopropylacrylamide) (PNIPA) in water-solvent mixtures was investigated.
TL;DR: The results indicate that the competition for nutrients among normal and cancer cells may be a determining factor in generating papillary tumor morphology.
Abstract: A nutrient-limited model for avascular cancer growth including cell proliferation, motility, and death is presented. The model qualitatively reproduces commonly observed morphologies for primary tumors, and the simulated patterns are characterized by its gyration radius, total number of cancer cells, and number of cells on tumor periphery. These very distinct morphological patterns follow Gompertz growth curves, but exhibit different scaling laws for their surfaces. Also, the simulated tumors incorporate a spatial structure composed of a central necrotic core, an inner rim of quiescent cells and a narrow outer shell of proliferating cells in agreement with biological data. Finally, our results indicate that the competition for nutrients among normal and cancer cells may be a determining factor in generating papillary tumor morphology.
TL;DR: In this article, a model was presented, for which the absorbed microwave power was obtained by solving Maxwell's equations and then incorporated as a source term in the transient heat equation, and the proposed methodology was then applied to simulate microwave heating of foodstuffs.
TL;DR: A review is presented on the observation of the resonant Raman spectra from one isolated single wall carbon nanotubes, focusing on the important structural information that is provided by single nanotube spectroscopy including the (n, m) determination of the individual tubes.
Abstract: A review is presented on the observation of the resonant Raman spectra from one isolated single wall carbon nanotube, focusing on the important structural information that is provided by single nanotube spectroscopy including the (n, m) determination of the individual tubes. The special sensitivity of the radial breathing mode to the (n, m) determination is emphasized, and the corroboration of this (n, m) assignment by diameter- and chirality-dependent phenomena in other Raman modes, such as the G-band, D-band, and G‘-band features is also discussed. The significance of single nanotube spectroscopy for future nanotube research in general is briefly reviewed.
TL;DR: The stimuli and mechanisms underlying chemokine production following infection in vitro and in vivo are examined and the ability of chemokines to coordinate the influx of inflammatory and immune cells to the site of parasite infection, and to control T. cruzi growth is examined.
DOI•
01 Jan 2002TL;DR: In this article, a trabalho discute o papel das atividades praticas no ensino de ciencias e reve como o laboratorio escolar de Ciença tem been used.
Abstract: Este trabalho discute o papel das atividades praticas no ensino de ciencias e reve como o laboratorio escolar de ciencias tem sido usado. Discute os pressupostos sobre a natureza do conhecimento que suportam esses usos e os equivocos a que conduzem. Descreve algumas alternativas potencialmente mais relevantes e pedagogicamente interessantes que temos estudado, em contraste com os tipos de atividades fortemente estruturadas tradicionalmente utilizadas pelos professores. Em particular, defende a adocao de uma ampla gama de atividades pratico-experimentais − nao necessariamente dirigidas como os tradicionais roteiros experimentais − e uma mudanca de foco do trabalho no laboratorio, com o objetivo de deslocar o nucleo das atividades dos estudantes da exclusiva manipulacao de equipamentos, preparacao de montagens e realizacao de medidas, para outras atividades que se aproximam mais do fazer ciencia. Essas atividades mais envolvem a manipulacao de interpretacoes e ideias sobre observacoes e fenomenos que objetos, com o proposito de produzir conhecimento. Entre elas: a analise e interpretacao dos resultados, a reflexao sobre as implicacoes destes e a avaliacao da qualidade das evidencias que suportam as conclusoes obtidas.
TL;DR: It is shown that after ischemia and reperfusion (I/R) injury, TSG-14tg mice have an impaired survival rate, which appeared secondary to a markedly increased inflammatory response, as assessed by the local (duodenum and ileum) and remote (lung) enhancement in vascular permeability, hemorrhage, and neutrophil accumulation.
Abstract: TSG-14/PTX3 is a gene inducible by tumor necrosis factor (TNF)-α, interleukin-1β, and lipopolysaccharide in fibroblasts, macrophages, and endothelial cells. It encodes a 42-kd secreted glycoprotein that belongs to the pentraxin family of acute-phase proteins. Recently, we demonstrated that TSG-14 transgenic mice (TSG-14tg) overexpressing the murine TSG-14 gene under control of its own promoter are more resistant to lipopolysaccharide-induced shock and to polymicrobial sepsis caused by cecal ligation and puncture. Here we show that after ischemia and reperfusion (I/R) injury, TSG-14tg mice have an impaired survival rate, which appeared secondary to a markedly increased inflammatory response, as assessed by the local (duodenum and ileum) and remote (lung) enhancement in vascular permeability, hemorrhage, and neutrophil accumulation. Moreover, tissue concentrations of TNF-α, interleukin-1β, KC, and MCP-1 were higher in TSG-14tg as compared to wild-type mice after I/R injury. Of note, elevated TNF-α concentrations in serum were only observed in TSG-14tg mice and blockage of TNF-α action prevented lethality of TSG-14tg mice. These results demonstrate that transgenic expression of TSG-14 induces an enhanced local and systemic injury and TNF-α-dependent lethality after I/R. Taken together, our data point to a critical role of TSG-14 in controlling acute inflammatory response in part via the modulation of TNF-α expression.
TL;DR: Hexane, chloroform and ethanol extracts of six marine macroalgae from North Ceara coast (Northeast Brazil) were evaluated for antibacterial activity by the single disk method and best results were shown by the hexane extracts of Amansia multifida against enteric Gram-negative strains.
TL;DR: In this paper, the authors analyzed the room-temperature linewidth for several Raman features (i.e., the radial breathing mode, the G band, the D band, and the ${G}^{\ensuremath{'}}$ ) observed for individual isolated single-wall carbon nanotubes (SWNTs).
Abstract: In this work we analyze the room-temperature linewidth for several Raman features (i.e., the radial breathing mode, the G band, the D band, and the ${G}^{\ensuremath{'}}$ band) observed for individual isolated single-wall carbon nanotubes (SWNTs). Temperature-dependent measurements on SWNT bundles and isolated SWNTs show that anharmonic effects are not important for linewidth broadening at room temperature. Measurements on a large number of samples (170 isolated SWNTs) allow us to filter out the effect from extrinsic SWNT properties (e.g., defects, tube deformations, substrate roughness) and to obtain information about intrinsic properties related to phonon and electron dispersion relations, curvature and Breit-Wigner-Fano effects, single- vs double-resonance Raman scattering processes, and the resonance condition itself through a linewidth analysis. We also use observations at the single-nanotube level to understand linewidth effects in SWNT bundles.
TL;DR: Propolis collected from a cerrado area in Minas Gerais State, Brazil, was subjected to chromatography on silica gel column and to partition between immiscible solvents and yielded fractions which were active against bacteria.
TL;DR: The evitability approach of perinatal deaths in Brazil is highly recommended, as mortality rates are still very high and most of the deaths are considered avoidable.
Abstract: This is a literature review onperinatal mortality focusing its evitability. A Medline and Lilacs (Latin-America and Caribbean) search was conducted for the 90s. There are few research studies on this subject in Brazil due to the great number of underreported fetal deaths and the low quality information provided in death certificates. Different proposals for perinatal death classification are presented. Most are based on grouping the underlying causes of deaths in a functional system in order to facilitate the analysis. In the Wigglesworth classification system, one of the most recommended methods, deaths are related to the different stages of care for pregnant women and children, evidencing the possibilities of their prevention. The evitability approach of perinatal deaths in Brazil is highly recommended, as mortality rates are still very high and most of the deaths are considered avoidable. Premature deaths could be avoided improving the quality of health care. Besides improving the medical assistance, the organization of health care regarding pre-natal, birth and neonatal care must also be better developed to ensure access to qualified assistance.
01 Feb 2002
TL;DR: This paper presents DEByE (Data Extraction By Example), an approach to extracting data from Web sources, based on a small set of examples specified by the user, which adopts nested tables as its visual paradigm.
Abstract: In this paper we present DEByE(Data Extraction By Example), an approach to extracting data from Web sources, based on a small set of examples specified by the user. The novelty is in the fact that the user specifies examples according to a structure of his liking and that this structure is described at example specification time. For the specification of the examples, the user interacts with a tool we developed which adopts nested tables as its visual paradigm. Nested tables are simple, intuitive, and allow shielding the user from technical details (such as HTML tags, formatting operators, and learning automata) related to the extraction problem. The examples provided by the user are then used to generate patterns which allow extracting data from new documents. For the extraction, DEByE adopts a new bottom-up procedure we proposed which is very effective with various Web sources, as demonstrated by our experiments.
TL;DR: In this paper, the effect of the therapeutic range of ultrasound on NO induction and prostaglandin E 2 (PGE 2 ) production in vitro was investigated, and two ultrasound machines were evaluated, a traditional 1 MHz, pulsed 1:4, tested at four intensities, and a 45 kHz, continuous, also tested at different intensities.
TL;DR: The epidemiology of bovine, swine, ovine, caprine, and canine brucellosis in Brazil is reviewed and the zoonotic aspects of Brucella infection in Brazil are discussed.
TL;DR: The specific enterotoxins found in each of the two outbreaks implicate the source of contamination in the first out break to be the food handlers and for the second case cattle mastitis.
28 May 2002
TL;DR: To speed up the BP algorithm, it is augmented by a pruning procedure and a novel technique, inspired by the 20 Questions (divide-and-conquer) search strategy, called "focused message updating," resulting in an algorithm that detects and localizes shapes in grayscale images in as little as several seconds on an 850 MHz AMD processor.
Abstract: A novel deformable template is presented which detects and localizes shapes in grayscale images. The template is formulated as a Bayesian graphical model of a two-dimensional shape contour, and it is matched to the image using a variant of the belief propagation (BP) algorithm used for inference on graphical models. The algorithm can localize a target shape contour in a cluttered image and can accommodate arbitrary global translation and rotation of the target as well as significant shape deformations, without requiring the template to be initialized in any special way (e.g. near the target).The use of BP removes a serious restriction imposed in related earlier work, in which the matching is performed by dynamic programming and thus requires the graphical model to be tree-shaped (i.e. without loops). Although BP is not guaranteed to converge when applied to inference on non-tree-shaped graphs, we find empirically that it does converge even for deformable template models with one or more loops. To speed up the BP algorithm, we augment it by a pruning procedure and a novel technique, inspired by the 20 Questions (divide-and-conquer) search strategy, called "focused message updating." These modifications boost the speed of convergence by over an order of magnitude, resulting in an algorithm that detects and localizes shapes in grayscale images in as little as several seconds on an 850 MHz AMD processor.
TL;DR: Findings indicate the important role of endogenous IFN-γ and IRF-1 in the in vivo induction of the Trp-Kyn metabolic pathway during acute infection with Toxoplasma gondii.
Abstract: The induction of indoleamine 2,3-dioxygenase (INDO) expression and the tryptophan (Trp)-kynurenine (Kyn) metabolic pathway during in vivo infection with Toxoplasma gondii was investigated. Decreased levels of Trp and increased formation of Kyn were observed in the lungs, brain, and serum from mice infected with T. gondii. Maximal INDO mRNA expression and enzyme activity were detected in the lungs at 10 to 20 days postinfection. Further, the induction of INDO mRNA expression, Trp degradation and Kyn formation were completely absent in tissues from mice deficient in IFN-γ (IFN-γ−/−) or IFN regulatory factor -1 (IRF-1−/−). These findings indicate the important role of endogenous IFN-γ and IRF-1 in the in vivo induction of the Trp-Kyn metabolic pathway during acute infection with T. gondii. In contrast, expression of INDO mRNA and its activity was preserved in the tissues of TNF-receptor p55- or inducible nitric oxide synthase-deficient mice infected with T. gondii. Together with the results showing the extreme susceptibility of the IFN-γ−/− and the IRF-1−/− mice to infection with T. gondii, our results indicate a possible involvement of INDO and Trp degradation in host resistance to early infection with this parasite.
TL;DR: The nondominated sorting genetic algorithm (NSGA) is presented to solve multiobjective optimization problems solved by evolutionary algorithms and its performance is analyzed by comparing its results with those obtained with four other algorithms.
Abstract: In this paper, we discuss multiobjective optimization problems solved by evolutionary algorithms. We present the nondominated sorting genetic algorithm (NSGA) to solve this class of problems and its performance is analyzed by comparing its results with those obtained with four other algorithms. Finally, the NSGA is applied to solve the TEAM benchmark problem 22 without considering the quench physical condition to map the Pareto-optimum front. The results in both analytical and electromagnetic problems show its effectiveness.