224 research outputs found
Effects of mechanical agitation and of the addition of grain refiner on the microstructure and mechanical properties of castings of the Al-Sn alloy.
The aim of this article was to evaluate the effects of mechanical stirring and grain refiner addition in three different Al-10wt% Sn casting alloys on their resulting macro and microstructures and mechanical properties. These samples were obtained by using: i) die casting, ii) casting with mechanical stirring, iii) die casting using grain refiner (master alloy Al-5wt% Ti-1wt% B) and iv) die casting with grain refiner and mechanical stirring. Experimental results presented different mean grain sizes and different cooling rates when different casting procedures were applied. Cellular and dendritic morphologies were observed when ranges of cooling rates of about 0.6 to 0.75 degrees C/s and of 1.75 to 2.55 degrees C/s were employed, respectively. Porosity levels of all studied alloy samples were also analyzed. Results of the mechanical behavior, particularly, ultimate tensile strength, yield strength and specific elongation were correlated with mean grain sizes, dendritic arm and cellular spacings and porosity levels attained for the three different cast Al-10wt% Sn alloy samples. The control of the resulting microstructure of the as-cast product may be used as an alternative way to produce sound casting alloy components with improvement in the mechanical properties.14390691
Genetic relationship of diarrheagenic Escherichia coli pathotypes among the enteropathogenic Escherichia coli O serogroup
Trust transitivity in social networks
Non-centralized recommendation-based decision making is a central feature of
several social and technological processes, such as market dynamics,
peer-to-peer file-sharing and the web of trust of digital certification. We
investigate the properties of trust propagation on networks, based on a simple
metric of trust transitivity. We investigate analytically the percolation
properties of trust transitivity in random networks with arbitrary degree
distribution, and compare with numerical realizations. We find that the
existence of a non-zero fraction of absolute trust (i.e. entirely confident
trust) is a requirement for the viability of global trust propagation in large
systems: The average pair-wise trust is marked by a discontinuous transition at
a specific fraction of absolute trust, below which it vanishes. Furthermore, we
perform an extensive analysis of the Pretty Good Privacy (PGP) web of trust, in
view of the concepts introduced. We compare different scenarios of trust
distribution: community- and authority-centered. We find that these scenarios
lead to sharply different patterns of trust propagation, due to the segregation
of authority hubs and densely-connected communities. While the
authority-centered scenario is more efficient, and leads to higher average
trust values, it favours weakly-connected "fringe" nodes, which are directly
trusted by authorities. The community-centered scheme, on the other hand,
favours nodes with intermediate degrees, in detriment of the authorities and
its "fringe" peers.Comment: 11 pages, 9 figures (with minor corrections
Tabagismo associado a outros fatores comportamentais de risco de doenças e agravos crônicos não transmissíveis
Noncompliance in people living with HIV: accuracy of defining characteristics of the nursing diagnosis
Perceptions and practices of Angolan health care professionals concerning intimate partner violence against women
HPV infection and p53 and p16 expression in esophageal cancer: are they prognostic factors?
Background: Esophageal squamous cell carcinoma (ESCC) is a highly lethal malignant tumor. Currently, Human papillomavirus (HPV) is suggested as a potential risk factor for esophageal cancer (EC) in addition to the classic risk factors, alcohol and tobacco, but this hypothesis still remains contradictory. We sought to investigate wether HPV and well-known biomarkers (p16 and p53) and patient-related factors that may have impact on survival of ESCC.
Methods: We conducted a prospective cohort study. By using multiplex PCR, we determined the prevalence of high risk HPV in ESCC, and evaluated the immunohistochemical expression of p16 and p53, molecular markers related to esophageal carcinogenesis in order to verify the potential influence of these variables in patients's survival. Survival rates were estimated using Kaplan-Meier methods. A multivariate confirmatory model was performed using Cox proportional hazards regression.
Results: Twelve (13.8%) of 87 patients were HPV-DNA positive. Positive reactions of p16 and p53 were 10.7% and 68.6%, respectively. Kaplan-Meier analysis indicated that men (p = 0.025) had poor specific-cancer survival and a shorter progression-free survival (p = 0.050) as compared to women; III or IV clinical stage (p < 0.019) had poor specific-cancer survival and a shorter progression-free survival (p < 0.001) compared to I and II clinical stage; not submitted to surgery (< 0.001) and not submitted to chemoradiotherapy (p = 0.039) had a poor specific-cancer survival, as well. The multivariate analysis showed that HPV, p16 and p53 status are not predictive parameters of progression-free and specific-cancer survival.
Conclusion: HPV infection and p53 and p16 expression are not prognostic factors in ESCC.CNPq Universal for providing supplies to the largest study, of which this
study is a part of, entitled “The role of human papillomavirus (HPV) as the
etiologic agent of esophageal cancer. A cross-sectional study, case-control
and longitudinal at Barretos Cancer Hospital”; (Grant number 482666/2012–9
to ALF); INCT HPV [Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) [Grant number 08/57889–1 to LLV]; Conselho Nacional de
Desenvolvimento Científico e Tencnológico (CNPq) (Grant number 573799/
2008–3 to LLV)].info:eu-repo/semantics/publishedVersio
Dual-curing, self-adhesive resin cement: influence of the polymerization modes on the degree of conversion and microhardness
Motivos para frequentar um programa de educação permanente: relato dos alunos da universidade aberta à terceira idade da Escola de Artes, Ciências e Humanidades da Universidade de São Paulo
- …