437 research outputs found
Renormalization: a quasi-shuffle approach
In recent years, the usual BPHZ algorithm for renormalization in perturbative
quantum field theory has been interpreted, after dimensional regularization, as
a Birkhoff decomposition of characters on the Hopf algebra of Feynman graphs,
with values in a Rota-Baxter algebra of amplitudes. We associate in this paper
to any such algebra a universal semi-group (different in nature from the
Connes-Marcolli "cosmical Galois group"). Its action on the physical amplitudes
associated to Feynman graphs produces the expected operations: Bogoliubov's
preparation map, extraction of divergences, renormalization. In this process a
key role is played by commutative and noncommutative quasi-shuffle bialgebras
whose universal properties are instrumental in encoding the renormalization
process
O SUICÍDIO COMO ACIDENTE DE TRABALHO
The subject of this article is suicide as a work accident. The following problem was investigated: can suicide be considered a work accident? The following hypotheses were considered: "work organization as a condition for psychic imbalance and suicide" and "the relationship between work and fear". The overall objective is "characterization of suicide as an occupational accident". The specific objectives are: "legal concept of work accident", "worker's psychic impact on work organization" and "causal link between work and suicide". This work is important from an individual perspective because of the complexity of the man-work relationship. For science, it is relevant for providing a breakthrough in the discipline of work psychopathology. It adds to society because it is a social problem to be faced, breaking cultural, social and religious barriers. This is a theoretical qualitative research lasting six months.O tema deste artigo é o suicídio como acidente de trabalho. Investigou-se o seguinte problema: o suicídio pode ser considerado um acidente de trabalho?. Cogitou-se as seguintes hipóteses, "organização do trabalho como condição para um desequilíbrio psíquico e para o suicídio" e "a relação trabalho e medo". O objetivo geral é "caracterização do suicídio como acidente de trabalho". Os objetivos específicos são: "conceito legal de acidente de trabalho", "impacto psíquico do trabalhador frente í organização do trabalho" e "nexo causal entre trabalho e suicídio". Este trabalho é importante em uma perspectiva individual, pela complexidade da relação homem-trabalho. Para a ciência, é relevante por proporcionar um avanço na disciplina de psicopatologia do trabalho. Agrega í sociedade pelo fato de ser um problema social a ser enfrentado, quebrando barreiras culturais, sociais e religiosas. Trata-se de uma pesquisa qualitativa teórica com duração de seis meses
Identification of two new protective pre-erythrocytic malaria vaccine antigen candidates
<p>Abstract</p> <p>Background</p> <p>Despite years of effort, a licensed malaria vaccine is not yet available. One of the obstacles facing the development of a malaria vaccine is the extensive heterogeneity of many of the current malaria vaccine antigens. To counteract this antigenic diversity, an effective malaria vaccine may need to elicit an immune response against multiple malaria antigens, thereby limiting the negative impact of variability in any one antigen. Since most of the malaria vaccine antigens that have been evaluated in people have not elicited a protective immune response, there is a need to identify additional protective antigens. In this study, the efficacy of three pre-erythrocytic stage malaria antigens was evaluated in a <it>Plasmodium yoelii</it>/mouse protection model.</p> <p>Methods</p> <p>Mice were immunized with plasmid DNA and vaccinia virus vectors that expressed one, two or all three <it>P. yoelii </it>vaccine antigens. The immunized mice were challenged with 300 <it>P. yoelii </it>sporozoites and evaluated for subsequent infection.</p> <p>Results</p> <p>Vaccines that expressed any one of the three antigens did not protect a high percentage of mice against a <it>P. yoelii </it>challenge. However, vaccines that expressed all three antigens protected a higher percentage of mice than a vaccine that expressed PyCSP, the most efficacious malaria vaccine antigen. Dissection of the multi-antigen vaccine indicated that protection was primarily associated with two of the three <it>P. yoelii </it>antigens. The protection elicited by a vaccine expressing these two antigens exceeded the sum of the protection elicited by the single antigen vaccines, suggesting a potential synergistic interaction.</p> <p>Conclusions</p> <p>This work identifies two promising malaria vaccine antigen candidates and suggests that a multi-antigen vaccine may be more efficacious than a single antigen vaccine.</p
Platinum–Vanadium Oxide Nanotube Hybrids
The present contribution reports on the features of platinum-based systems supported on vanadium oxide nanotubes. The synthesis of nanotubes was carried out using a commercial vanadium pentoxide via hydrothermal route. The nanostructured hybrid materials were prepared by wet impregnation using two different platinum precursors. The formation of platinum nanoparticles was evaluated by applying distinct reduction procedures. All nanostructured samples were essentially analysed by X-ray diffraction and transmission electron microscopy. After reduction, transmission electron microscopy also made it possible to estimate particle size distribution and mean diameter calculations. It could be seen that all reduction procedures did not affect the nanostructure of the supports and that the formation of metallic nanoparticles is quite efficient with an indistinct distribution along the nanotubes. Nevertheless, the reduction procedure determined the diameter, dispersion and shape of the metallic particles. It could be concluded that the use of H2PtCl6 is more suitable and that the use of hydrogen as reducing agent leads to a nanomaterial with unagglomerated round-shaped metallic particles with mean size of 6–7 nm
Regional Comprehensive Economic Partnership (RCEP): Impact on the Integration of Textile and Apparel Supply Chain in the Asia-Pacific Region
this study intends to evaluate how will the implementation of the RCEP affect the integration of textile and apparel (T&A) supply chain in the Asia-Pacific region
Factors influencing the growth hormone peak and plasma insulin-like growth factor I in young adults with pituitary stalk interruption syndrome
Genetic characterization of morphologically variant strains of Paracoccidioides brasiliensis
Molecular characterization of Paracoccidioides brasiliensis variant strains that had been preserved under mineral oil for decades was carried out by random amplified polymorphic DNA analysis (RAPD). On P. brasiliensis variants in the transitional phase and strains with typical morphology, RAPD produced reproducible polymorphic amplification products that differentiated them. A dendrogram based on the generated RAPD patterns placed the 14 P. brasiliensis strains into five groups with similarity coefficients of 72%. A high correlation between the genotypic and phenotypic characteristics of the strains was observed. A 750 bp-RAPD fragment found only in the wild-type phenotype strains was cloned and sequenced. Genetic similarity analysis using BLASTx suggested that this RAPD marker represents a putative domain of a hypothetical flavin-binding monooxygenase (FMO)-like protein of Neurospora crassa.FiocruzBritish Council Progra
Digital subtraction radiographic analysis of the combination of bioabsorbable membrane and bovine morphogenetic protein pool in human periodontal infrabony defects
Objectives: This study assessed the bone density gain and its relationship with the
periodontal clinical parameters in a case series of a regenerative therapy procedure.
Material and Methods: Using a split-mouth study design, 10 pairs of infrabony defects from
15 patients were treated with a pool of bovine bone morphogenetic proteins associated with
collagen membrane (test sites) or collagen membrane only (control sites). The periodontal
healing was clinically and radiographically monitored for six months. Standardized presurgical
and 6-month postoperative radiographs were digitized for digital subtraction
analysis, which showed relative bone density gain in both groups of 0.034 ± 0.423 and
0.105 ± 0.423 in the test and control group, respectively (p>0.05). Results: As regards the
area size of bone density change, the influence of the therapy was detected in 2.5 mm2 in
the test group and 2 mm2 in the control group (p>0.05). Additionally, no correlation was
observed between the favorable clinical results and the bone density gain measured by
digital subtraction radiography (p>0.05). Conclusions: The findings of this study suggest
that the clinical benefit of the regenerative therapy observed did not come with significant
bone density gains. Long-term evaluation may lead to a different conclusions
Nuclear expression of Rac1 in cervical premalignant lesions and cervical cancer cells
<p>Abstract</p> <p>Background</p> <p>Abnormal expression of Rho-GTPases has been reported in several human cancers. However, the expression of these proteins in cervical cancer has been poorly investigated. In this study we analyzed the expression of the GTPases Rac1, RhoA, Cdc42, and the Rho-GEFs, Tiam1 and beta-Pix, in cervical pre-malignant lesions and cervical cancer cell lines.</p> <p>Methods</p> <p>Protein expression was analyzed by immunochemistry on 102 cervical paraffin-embedded biopsies: 20 without Squamous Intraepithelial Lesions (SIL), 51 Low- grade SIL, and 31 High-grade SIL; and in cervical cancer cell lines C33A and SiHa, and non-tumorigenic HaCat cells. Nuclear localization of Rac1 in HaCat, C33A and SiHa cells was assessed by cellular fractionation and Western blotting, in the presence or not of a chemical Rac1 inhibitor (NSC23766).</p> <p>Results</p> <p>Immunoreacivity for Rac1, RhoA, Tiam1 and beta-Pix was stronger in L-SIL and H-SIL, compared to samples without SIL, and it was significantly associated with the histological diagnosis. Nuclear expression of Rac1 was observed in 52.9% L-SIL and 48.4% H-SIL, but not in samples without SIL. Rac1 was found in the nucleus of C33A and SiHa cells but not in HaCat cells. Chemical inhibition of Rac1 resulted in reduced cell proliferation in HaCat, C33A and SiHa cells.</p> <p>Conclusion</p> <p>Rac1 is expressed in the nucleus of epithelial cells in SILs and cervical cancer cell lines, and chemical inhibition of Rac1 reduces cellular proliferation. Further studies are needed to better understand the role of Rho-GTPases in cervical cancer progression.</p
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