391 research outputs found

    Considering the stiffness of the forming tools in the numerical analysis of the ironing process

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    Ironing can occur in cylindrical cup drawing whenever the thickness of the drawn flange is larger than the gap between the punch and the die. This is particularly relevant for materials that present r-values lower than 1.0, such as the aluminium alloys, since they tend to present more thickening of the flange. The aim of this study is to evaluate numerically the impact of the elastic deformation of the forming tools on the final cup geometry, i.e., the earing profile and the evolution of thickness along the circumferential direction, at different heights. Different contact conditions are also analysed since they strongly affect both the thickness strain and the earing profile. The process conditions considered are the ones from EXACT, the ESAFORM Benchmark 2021, enabling the comparison with experimental results. Considering the deformation of the forming tools mainly impacts the ironing stage, enabling predicting wall thickness values larger than the gap between the punch and the die.The authors gratefully acknowledge the financial support of the Portuguese Foundation for Science and Technology (FCT) under projects with reference 2022.08459.PTDC, UIDB/00285/2020 and LA/P/0112/2020

    On the effect of the tension-compression ratio on forming of isotropic materials

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    It is generally believed that the choice of the yield criterion used to describe the plastic behaviour of isotropic metallic materials does not affect much the accuracy of the predictions of forming operations. For this reason, the von Mises yield criterion is widely used for modelling their plastic behaviour. However, according to the von Mises yield criterion, the ratio between the yield stresses in tension and compression is always 1.0. Nevertheless, materials can present same asymmetry, i.e. a strength differential (SD) effect. In this work, the yield criterion proposed by Cazacu et al. [1], is adopted to describe the mechanical behaviour of isotropic materials, with different levels of tension-compression asymmetry. Numerical simulations of the deep drawing of a cylindrical cup were performed considering these different virtual isotropic materials, in order to evaluate its impact on the thickness distribution and cup height. The analysis of the stress and strain paths, for material points initially located in the flange is performed, enabling the correlation between the thickness distributions predicted and the plastic strain ratios obtained analytically, using the yield function and the normality rule. The results show that even small changes in the tension-compression stress ratio can influence the strains distribution, in isotropic materials.The authors gratefully acknowledge the financial support of the projects POCI-01-0145-FEDER30592 (PTDC/EME-EME/30592/2017) and UIDB/00285/2020 financed by the Operational Program for Competitiveness and Internationalization, in its FEDER/FNR component, and the Portuguese Foundation of Science and Technology (FCT), in its State Budget component (OE)

    Temperate facultative cleaner wrasses selectively remove ectoparasites from their client-fish in the Azores

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    Cleaner fishes are key contributors to the health of fish communities. However, much of the information in the literature refers to tropical systems, while fewer studies have examined the activity of cleaner fish inhabiting temperate ecosystems. Facultative cleaner fish are assumed to clean only during their juvenile phase, and have a broader diet than obligatory cleaner fish. Here, we focused on 2 facultative cleaner fish species, Coris julis and Thalassoma pavo, that live along the temperate coasts of the Azorean island of São Miguel. We found that these species focused their cleaning activities on relatively few species of clients, which supports the general idea that facultative cleaner fishes in temperate waters are less dependent on cleaning interactions than obligatory cleaner fishes in tropical waters. Both cleaner species were found to give more bites per host when inspecting larger clients, likely because the latter typically host more parasites. We found that C. julis consumed a greater diversity of food items, which included gnathiid larvae and fewer caligid copepods, compared to T. pavo where no ectoparasites were found. All cleaner fish that we collected after observations of cleaning had eaten gnathiid isopod larvae but not caligid copepods, even though caligid copepods were the most abundant ectoparasite found on the body of 7 selected fish species (including both client and non-client species), suggesting that both species selectively feed on gnathiid isopods. This study is the first to demonstrate that temperate facultative cleaner fish species actively and selectively inspect and remove ectoparasites from their client-fish species.Fundação para a Ciência e Tecnologia (FCT, grant PTDC/MAR/105276/2008. European Regional Development Fund (ERDF) COMPETE - Operational Competitiveness Programme. FCT - Foundation for Science and Techno - project PEst-C/MAR/LA0015/2011.info:eu-repo/semantics/publishedVersio

    Epidemiological Profile of Precocious Neonatal Mortality in the Period 2008 to 2015 in Porto Velho, Rondonia, Brazil

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    The objective of this study was to describe the epidemiological profile of precocious neonatal infant mortality in the city of Porto Velho, Rondonia. A quantitative, descriptive study with an ecological approach was carried out. The data source used was secondary, originating from the linkage between SINASC and SIM databases, from the Health Surveillance Agency of the Rondonia Health Department. For treatment, absolute frequency analyzes were performed. The neonatal infant mortality rate was 9.7 deaths per thousand live births, with a predominance of the preterm neonatal patient: 7.2 deaths per thousand live births. Of the deaths, 482 (72.8%) occurred in the precocious neonatal period (0 to 6 days) and 164 (24.7%) in the late neonatal 7 to 27 days of life. The findings indicate the need to improve the quality of health care services available in the city, both prenatal and obstetric care in the neonatal period

    Hemoglobinopatias no Distrito Federal, Brasil

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    Em uma amostra de 3137 pessoas, residentes no Distrito Federal, foram detectadas as seguintes hemoglobinas: em 3009(95,92%) HbAA; em 91 (2,90%) HbAS; em 20(0,64%) HbAC; em 8 (0,26%) talassemia beta minor; em 5(0,16%) HbAJ alfa; em 3 (0,09%) HbAM e em 1 (0,03%) talassemia major associada com HbAS. A HbAS têm as seguintes freqüências, quanto ao grupo racial: branco - 1,84%; mulato claro 2,55%; mulato médio-3,68%; mulato escuro - 6,80%; negro -10,43% e mestiço de índio -3,85%.The hemoglobins of 3137 persons from the Federal District, Brazil was studied. The identified types of hemoglobins were: HbAA (3009 - 95,92%); HbAS (91 - 2,90%); HbAC (20 - 0,64%) beta thalassemia minor (8 - 0,26%); HbAJ alpha (5 - 0,16%); HbAM (3 - 0,09%) and beta thalassemia major/HbS (1 - 0,03%). The frequencies of sickle cell trait (HbAS) of each racial class were: white (1,84%); light mulatto (2,55%); medium mulatto (3,68%); dark mulatto(6,80%), negro (10,43%)and indian mestizo (3,85%)

    Relação pescoço-coxa como índice antropométrico para diagnóstico da síndrome metabólica em universitários brasileiros: promoção da saúde e prevenção de enfermidades

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    Cartel presentado en el 3er Congreso Internacional de Comunicación en Salud (3ICHC), celebrado los días 19 y 20 de octubre de 2017 en la Universidad Carlos III de Madrid.O objetivo deste estudo é investigar a RPC como índice antropométrico para diagnóstico da Síndrome Metabólic

    Mediterranean diet intervention alters the gut microbiome in older people reducing frailty and improving health status : the NU-AGE 1-year dietary intervention across five European countries

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    Objective Ageing is accompanied by deterioration of multiple bodily functions and inflammation, which collectively contribute to frailty. We and others have shown that frailty co-varies with alterations in the gut microbiota in a manner accelerated by consumption of a restricted diversity diet. The Mediterranean diet (MedDiet) is associated with health. In the NU-AGE project, we investigated if a 1-year MedDiet intervention could alter the gut microbiota and reduce frailty. Design We profiled the gut microbiota in 612 non-frail or pre-frail subjects across five European countries (UK, France, Netherlands, Italy and Poland) before and after the administration of a 12-month long MedDiet intervention tailored to elderly subjects (NU-AGE diet). Results Adherence to the diet was associated with specific microbiome alterations. Taxa enriched by adherence to the diet were positively associated with several markers of lower frailty and improved cognitive function, and negatively associated with inflammatory markers including C-reactive protein and interleukin-17. Analysis of the inferred microbial metabolite profiles indicated that the diet-modulated microbiome change was associated with an increase in short/branch chained fatty acid production and lower production of secondary bile acids, p-cresols, ethanol and carbon dioxide. Microbiome ecosystem network analysis showed that the bacterial taxa that responded positively to the MedDiet intervention occupy keystone interaction positions, whereas frailty-associated taxa are peripheral in the networks. Conclusion Collectively, our findings support the feasibility of improving the habitual diet to modulate the gut microbiota which in turn has the potential to promote healthier ageing.Peer reviewe
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