821 research outputs found

    Controlling inflation with timid monetary-fiscal regime changes

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    Can monetary policy control inflation when both monetary and fiscal policies change over time? When monetary policy is active, a long-run fiscal principle entails flexibility in fiscal policy that preserves determinacy even when deviating from passive fiscal, substantially for brief periods or timidly for prolonged periods. To guarantee a unique equilibrium, monetary and fiscal policies must coordinate not only within but also across regimes, and not simply on being active or passive, but also on their extent. The amplitude of deviations from the active monetary/passive fiscal benchmark determines whether a regime is Ricardian: timid deviations do not imply wealth effects

    The role of filler wire and scanning strategy in laser welding of difficult-to-weld aluminum alloys

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    Laser welding of dissimilar aluminum alloys has gained interest over recent years, especially for the production of lightweight components. Pore and crack formation is one of the most critical factors to be taken into consideration for such applications, in particular when one or more parts are produced by die casting or additive manufacturing (AM). Current laser systems offer several methods for defect reduction and process control, while optimized process strategies must be correlated to key factors influencing welding outcomes. In light of these aspects, the current paper investigates the welding of AA6082 sheets with AlSi10Mg parts produced by AM in a lap-joint configuration typical of battery housings in the e-mobility industry. Both laser welding with and without filler wire are investigated, along with the potential advantages of using a wobbling scanning strategy, in order to understand the impact of process strategies on weld bead quality. The importance of process parameter optimization is highlighted for all of the employed strategies, with special emphasis on defects, weld bead chemical composition, joint morphology, and dilution between the materials involved. The findings demonstrate that by introducing filler wire and employing active wobbling, highly reflective alloys can be welded correctly (porosity below 1%, equivalent ultimate strength up to 204 MPa) with good tolerance to variations in process parameters, while filler wire can be excluded in high-productivity welding where linear scanning is employed and detailed optimization of process parameters is performed (porosity below 2%, equivalent ultimate strength up to 190 MPa

    3D modelling of LASER hardening and tempering of hypo-eutectoid steels

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    In this paper a mathematical model solved by means of the finite differences method (FDM) for laser surface hardening of complex geometries is presented. The 3-D transient model characterizes a software package named Laser Hardening Simulator (LHS), which makes it possible to predict the extension of the treated area into the mechanical components and thus the hardened depth into the bulk material. The obtained microstructures and the resulting hardness with respect to the laser parameters and to the laser beam path strategy can be determined by considering the quenching and the tempering effects due to the overlapping trajectories. The initial workpiece microstructure is taken into account in the simulation by a digitized photomicrograph of the ferrite-pearlite distribution before the thermal cycle. In order to show the accuracy of the model, experimental trials were conducted on the keyway for spline machined on a hub made of SAE 1043. The domain discretization for the solution of the heat flux problem into the workpiece and for the diffusion of the carbon is carried out by means of a mesh generator strategy implemented into the code

    A new in situ test for the assessment of the rock-burst alarm threshold during tunnelling

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    Rock-burst is one of the most serious risks associated with hard rock tunnelling and mining at high depths. Monitoring of acoustic emissions emitted by the rock-mass during excavation and their interpretation now permits the early assessment of failure events and makes the safe management of the construction works possible. A reliable set-up of the alarm threshold is thus fundamental for the correct implementation of the procedures planned to minimise rock-burst related risk. This paper focuses on a novel in situ test specifically developed to provide an experimental basis for a more accurate assessment of the alarm threshold during tunnelling, representative of the local geomechanical conditions. The test, thanks to the compression induced by two flat jacks at the tunnel side wall, produces an artificial failure process during which acoustic emissions are measured and correlated to the mechanical response of the rock-mass, without the typical limitations of scale that characterised the laboratory experiments. The new methodology, named the Mules method, was successfully tested during the excavation of some stretches of the Brenner Base Tunnel in the Brixner granite, affected by mild spalling episodes. The case-history is fully described in the paper to illustrate the practical application of the proposed approach

    Simple technique for evacuation of traumatic subcutaneous haematomas under tension

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    BACKGROUND: Traumatic subcutaneous haematomas are common cases in the accident and emergency department. Occasionally, urgent evacuation is required to prevent skin necrosis. METHODS: We present a simple and safe technique, based on a principle similar to liposuction to evacuate traumatic subcutaneous haematomas under tension. Instruments readily available in the accident and emergency department are used without the need of general anaesthesia. RESULTS: The technique was performed in six cases without complication such as infection or re-collection of the haematoma under tension. We present two typical scenarios where urgent evacuation was indicated and the technique performed. CONCLUSION: The technique is useful as an urgent and safe procedure in the accident and emergency department setting

    Surface modification of mild steel using a combination of laser and electrochemical processes

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    Traditional methods for achieving hierarchical surface structures include highly specified, deterministic approaches to create features to meet design intention. In this study microstructural alteration was undertaken using laser apparatus and secondary texturing was achieved via succeeding electrochemical processes. Electrochemical jet machining (EJM) was performed on mild steel subjected to laser pre-treatment using power densities of 4167 and 5556 W/cm2 with pulse durations from 0.3 - 1.5 seconds. Results show that in combination, laser pre-treatment and EJM can alter the exposed surface textures and chemistries. Here, machined surface roughness (Sa) was shown to increase from approximately 0.45 µm for untreated surfaces to approximately 18 µm for surfaces subjected to extreme laser pretreatments. After pre-treatments materials were characterised to appraise microstructural changes, shown to be martensite formation, reinforced by complementary simulation data, and significant increases in observable hardness from approximately 261 HV for the asreceived material to over 700 HV after pre-treatment. The greater hardness was retained after EJM. Exposed martensitic lath structures at machined surfaces are shown to be partially responsible for surface roughness increases. The surfaces were explored with energy dispersive X-ray spectroscopy (EDS) and Raman spectroscopy demonstrating changes in apparent surface chemistry. This analysis revealed increasing oxide formation at the surface of the pre-treated EJM surface, a further contributory factor to surface roughness increases. This new process chain will be of interest to manufacturers seeking to control surface morphology for applications including micro-injection mould/die manufacture. While demonstrated here for steel similar mechanisms are exploitable in other material systems. A new technique has been demonstrated, resulting from the models and processes presented to couple laser and electrolyte jet processing for complex surface preparation

    Mutational screening of splicing factor genes in cases with autosomal dominant retinitis pigmentosa.

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    PURPOSE: Mutations in genes encoding proteins from the tri-snRNP complex of the spliceosome account for more than 12% of cases of autosomal dominant retinitis pigmentosa (adRP). Although the exact mechanism by which splicing factor defects trigger photoreceptor death is not completely clear, their role in retinitis pigmentosa has been demonstrated by several genetic and functional studies. To test for possible novel associations between splicing factors and adRP, we screened four tri-snRNP splicing factor genes (EFTUD2, PRPF4, NHP2L1, and AAR2) as candidate disease genes. METHODS: We screened up to 303 patients with adRP from Europe and North America who did not carry known RP mutations. Exon-PCR and Sanger methods were used to sequence the NHP2L1 and AAR2 genes, while the sequences of EFTUD2 and PRPF4 were obtained by using long-range PCRs spanning coding and non-coding regions followed by next-generation sequencing. RESULTS: We detected novel missense changes in individual patients in the sequence of the genes PRPF4 and EFTUD2, but the role of these changes in relationship to disease could not be verified. In one other patient we identified a novel nucleotide substitution in the 5' untranslated region (UTR) of NHP2L1, which did not segregate with the disease in the family. CONCLUSIONS: The absence of clearly pathogenic mutations in the candidate genes screened in our cohort suggests that EFTUD2, PRPF4, NHP2L1, and AAR2 are either not involved in adRP or are associated with the disease in rare instances, at least as observed in this study in patients of European and North American origin

    Informação, a melhor forma de incentivar a mulher a tornar-se protagonistas de suas escolhas

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    Trabalho apresentado no II Congresso Nacional do PROJETO RONDON, realizado em Florianópolis, SC, no período de 23 a 25 de setembro de 2015 - Universidade Federal de Santa Catarina.Introdução: Segundo dados do ano de 2011, da Política Nacional de Atenção Integral à Saúde da Mulher, a maior parte da população brasileira é do sexo feminino, motivo pelo qual considerou-se relevante a propositura de ações que motivassem a valorização da mulher Arariense, em vários e amplos aspectos, podendo-se citar como exemplos, a saúde reprodutiva, em consequência a maternidade, saúde e doenças de outros sistemas que não o reprodutivo, e, além das questões biológicas da mulher, o enfrentamento das desigualdades sociais e de gênero. Após esta análise, fez-se relevante a propositura, e posterior efetivação desta atividade, realizada no Rondon 2015.1 Operação Jenipapo, que preconizou atender a mulher no maior número possível de questões, em todos os seus âmbitos anteriormente citados, ou na maioria deles. Metodologia: A fim de atingir esse objetivo, a atividade foi planejada e posteriormente realizada em cinco módulos, que foram apresentados num total de oito horas de curso, tais quais, autoconhecimento físico e psicológico, câncer de colo de útero e de mama, doenças sexualmente transmissíveis, planejamento familiar com discussão de métodos anticoncepcionais e direitos da mulher. Para o efetivo desenvolvimento da proposta utilizou-se de materiais, como Datashow e caixa de som, para exposição de imagens e vídeos, protótipos, dos órgãos sexuais feminino e masculino, e material bibliográfico como cartilhas informativas relacionadas à saúde e a Lei Maria da Penha, além de preservativos para posterior distribuição entre as presentes. A metodologia ainda deu-se de forma dinâmica, por meio de perguntas (para o grupo ou para pessoas direcionadas), relato de experiências e manuseio do material, a fim de que as participantes não se intimidassem e pudessem aproveitar as informações e tirarem dúvidas. Resultado/Discussão: Tornar a mulher protagonista do auto-cuidado, além de empoderá-la a conhecer seu real papel e importância na sociedade e dentro da família da qual faz parte, por meio do conhecimento de seus direitos e deveres como cidadã foi a principal proposta desta ação. Sendo a metodologia dinâmica, instigante e participativa, o objetivo da atividade foi cumprido, tendo, ao final das atividades propostas, o número total de 50 mulheres presentes, de todas as faixas etárias, gestantes ou não. Conclusão: A ação possibilitou que as participantes se tornassem mais conscientes sobre a sua saúde e sua sexualidade como um todo. Estas informações, muitas vezes novas, aliadas às informações de seus Direitos contribuem para que as mesmas se tornassem protagonistas de suas escolhas

    The combined effects of the microcirculatory status and cardiopulmonary bypass on platelet count and function during cardiac surgery

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    ACKGROUND: Cardiac surgery with cardiopulmonary bypass is associated with important changes in the microcirculation, usually attributed to endothelial dysfunction. Another common finding of cardiac surgery is postoperative thrombocytopenia and platelet loss of function. OBJECTIVE: To investigate the association between microvascular flow pattern and postoperative changes in platelet count and function in cardiac surgery patients. METHODS: Twelve adult cardiac surgery patients received microvascular circulation (sidestream darkfield sublingual mucosa analysis) and platelet count and function (multiple electrode aggregometry ADPtest and TRAPtest) assessment before and after cardiopulmonary bypass. RESULTS: After cardiopulmonary bypass, sublingual microcirculation showed a significantly (P = 0.001) decreased microvascular flow index and increased heterogeneity index (P = 0.006). Platelet function significantly decrease after cardiopulmonary bypass both at ADPtest (P = 0.011) and TRAPtest (P = 0.002). Preoperative patterns of poor microvascular perfusion (low perfused vessels density and total vessels density) were significantly associated with lower values of post-cardiopulmonary bypass platelet function (ADPtest, P = 0.009, TRAPtest, P = 0.031) and count (P = 0.048). CONCLUSIONS: A preoperative disturbance of the microcirculation is associated with a greater postoperative platelet dysfunction. Endothelial damage, chemical and mechanical stimuli are the possible link between the two patterns
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