277 research outputs found
Roughness Signature of Tribological Contact Calculated by a New Method of Peaks Curvature Radius Estimation on Fractal Surfaces
This paper proposes a new method of roughness peaks curvature radii calculation and its application to tribological contact analysis as characteristic signature of tribological contact. This method is introduced via the classical approach of the calculation of radius of asperity. In fact, the proposed approach provides a generalization to fractal profiles of the Nowicki's method [Nowicki B. Wear Vol.102, p.161-176, 1985] by introducing a fractal concept of curvature radii of surfaces, depending on the observation scale and also numerically depending on horizontal lines intercepted by the studied profile. It is then established the increasing of the dispersion of the measures of that lines with that of the corresponding radii and the dependence of calculated radii on the fractal dimension of the studied curve. Consequently, the notion of peak is mathematically reformulated. The efficiency of the proposed method was tested via simulations of fractal curves such as those described by Brownian motions. A new fractal function allowing the modelling of a large number of physical phenomena was also introduced, and one of the great applications developed in this paper consists in detecting the scale on which the measurement system introduces a smoothing artifact on the data measurement. New methodology is applied to analysis of tribological contact in metal forming process
Productive restructuring and the reallocation of work and employment: a survey of the “new” forms of social inequality
O propósito do presente artigo consiste
em questionar a inevitabilidade dos processos de
segmentação e precarização das relações de trabalho
e emprego, responsáveis pela inscrição de
“novas” formas de desigualdade social que alicerçam
o actual modelo de desenvolvimento das economias
e sociedades. Visa-se criticar os limites da
lógica econômica e financeira, de contornos globais,
que configuram um “novo espírito do capitalismo”,
ou seja, uma espécie de divinização da
ordem natural das coisas. Impõe-se fazer, por isso,
um périplo analítico pelas transformações em curso
no mercado de trabalho, acompanhado pela vigilância
epistemológica que permita enquadrar e
relativizar as (di)visões neoliberais e teses tecnodeterministas
dominantes. A perspectivação de cenários
sobre o futuro do trabalho encerrará este
périplo, permitindo-nos alertar para os condicionalismos
histórico-temporais, para a urgência de
se desocultar o que de ideológico e político existe
nas actuais lógicas de racionalização e para os
processos de ressimbolização do trabalho e emprego
enquanto “experiência social central” na
contemporaneidade.The scope of this paper is to question
the inevitability of the processes of segmentation
and increased precariousness of the relations
of labor and employment, which are responsible
for the introduction of “new” forms of
social inequality that underpin the current model
of development of economies and societies. It
seeks to criticize the limits of global financial and
economic logic, which constitute a “new spirit of
capitalism,” namely a kind of reverence for the
natural order of things. It is therefore necessary
to conduct an analytical survey of the ongoing
changes in the labor market, accompanied by epistemological
vigilance which makes it possible to
see neoliberal (di)visions and dominant technodeterministic
theses in context. The enunciation
of scenarios on the future of work will conclude
this survey and will make it possible to draw attention
to both the historical and temporal constraints
and to the urgent need to unveil what is
ideological and political in the prevailing logic of
rationalization and processes to reinstate work
and employment as a “central social experience”
in contemporary times
Clinical features and risk factors for severe and critical pregnant women with 2009 pandemic H1N1 influenza infection in China
<p>Abstract</p> <p>Background</p> <p>2009 pandemic H1N1 (pH1N1) influenza posed an increased risk of severe illness among pregnant women. Data on risk factors associated with death of pregnant women and neonates with pH1N1 infections are limited outside of developed countries.</p> <p>Methods</p> <p>Retrospective observational study in 394 severe or critical pregnant women admitted to a hospital with pH1N1 influenza from Sep. 1, 2009 to Dec. 31, 2009. rRT-PCR testing was used to confirm infection. In-hospital mortality was the primary endpoint of this study. Univariable logistic analysis and multivariate logistic regression analysis were used to investigate the potential factors on admission that might be associated with the maternal and neonatal mortality.</p> <p>Results</p> <p>394 pregnant women were included, 286 were infected with pH1N1 in the third trimester. 351 had pneumonia, and 77 died. A PaO<sub>2</sub>/FiO<sub>2 </sub>≤ 200 (odds ratio (OR), 27.16; 95% confidence interval (CI), 2.64-279.70) and higher BMI (i.e. ≥ 30) on admission (OR, 1.26; 95% CI, 1.09 to 1.47) were independent risk factors for maternal death. Of 211 deliveries, 146 neonates survived. Premature delivery (OR, 4.17; 95% CI, 1.19-14.56) was associated neonatal mortality. Among 186 patients who received mechanical ventilation, 83 patients were treated with non-invasive ventilation (NIV) and 38 were successful with NIV. The death rate was lower among patients who initially received NIV than those who were initially intubated (24/83, 28.9% vs 43/87, 49.4%; <it>p </it>= 0.006). Septic shock was an independent risk factor for failure of NIV.</p> <p>Conclusions</p> <p>Severe hypoxemia and higher BMI on admission were associated with adverse outcomes for pregnant women. Preterm delivery was a risk factor for neonatal death among pregnant women with pH1N1 influenza infection. NIV may be useful in selected pregnant women without septic shock.</p
Induction of the interleukin 6/ signal transducer and activator of transcription pathway in the lungs of mice sub-chronically exposed to mainstream tobacco smoke
<p>Abstract</p> <p>Background</p> <p>Tobacco smoking is associated with lung cancer and other respiratory diseases. However, little is known about the global molecular changes that precede the appearance of clinically detectable symptoms. In this study, the effects of mainstream tobacco smoke (MTS) on global transcription in the mouse lung were investigated.</p> <p>Methods</p> <p>Male C57B1/CBA mice were exposed to MTS from two cigarettes daily, 5 days/week for 6 or 12 weeks. Mice were sacrificed immediately, or 6 weeks following the last cigarette. High density DNA microarrays were used to characterize global gene expression changes in whole lung. Microarray results were validated by Quantitative real-time RT-PCR. Further analysis of protein synthesis and function was carried out for a select set of genes by ELISA and Western blotting.</p> <p>Results</p> <p>Globally, seventy nine genes were significantly differentially expressed following the exposure to MTS. These genes were associated with a number of biological processes including xenobiotic metabolism, redox balance, oxidative stress and inflammation. There was no differential gene expression in mice exposed to smoke and sampled 6 weeks following the last cigarette. Moreover, cluster analysis demonstrated that these samples clustered alongside their respective controls. We observed simultaneous up-regulation of <it>interleukin 6 </it>(<it>IL-6</it>) and its antagonist, <it>suppressor of cytokine signalling </it>(<it>SOCS3</it>) mRNA following 12 weeks of MTS exposure. Analysis by ELISA and Western blotting revealed a concomitant increase in total IL-6 antigen levels and its downstream targets, including phosphorylated signal transducer and activator of transcription 3 (Stat3), basal cell-lymphoma extra large (BCL-XL) and myeloid cell leukemia 1 (MCL-1) protein, in total lung tissue extracts. However, in contrast to gene expression, a subtle decrease in total SOCS3 protein was observed after 12 weeks of MTS exposure.</p> <p>Conclusion</p> <p>Global transcriptional analysis identified a set of genes responding to MTS exposure in mouse lung. These genes returned to basal levels following smoking cessation, providing evidence to support the benefits of smoking cessation. Detailed analyses were undertaken for IL-6 and its associated pathways. Our results provide further insight into the role of these pathways in lung injury and inflammation induced by MTS.</p
- …