2,698 research outputs found

    Formation of spin and charge ordering in the extended Hubbard model during a finite-time quantum quench

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    We investigate the formation of charge and spin ordering by starting from a non-interacting state and studying how it evolves in time under a Hamiltonian with finite electronic interactions. We consider the one-dimensional, half-filled extended Hubbard model, which we solve within time-dependent density matrix renormalization group. By employing linear finite-time quenches in the onsite and nearest-neighbor interactions, we find the existence of impulse, intermediate, and adiabatic regimes of time evolution. For the quenches we analyze, we observe that the adiabatic regime is reached with distinct ramping time scales depending on whether the charge density wave (CDW) or the spin density wave (SDW) is formed. The former needs to be slower than the latter to prevent entangled excited states from being accessed during the quench. More interestingly, in the intermediate regime, we observe an enhancement of the entanglement entropy with respect to its initial value, which precedes the formation of the CDW ordering; a similar enhancement is not seen in the quench towards SDW. Our findings also show that the breaking of the system integrability, by turning on the nearest-neighbor interactions, does not give rise to significant changes in the non-equilibrium behavior within the adiabatic approximation

    Sources of uncertainty in the closed-loop supply chain of lithium-ion batteries for electric vehicles

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    Due to increasing demand for electric vehicles and short innovation circles of battery, production, and recycling technology, different uncertainties need to be faced at different stages of the supply chain. However, a qualitative analysis of the uncertainties and their sources is missing. Therefore, in this paper the authors propose an empirical approach to the identification of uncertainty occurring in the closed-loop supply chain of lithium-ion batteries from electric vehicles (uncertainty in supply, process, demand, control, and environmental uncertainty). The investigation methodology consists of a content analysis of press media documents related to electric vehicles and the automotive industry. The final content analysis comprises 102 evidences of uncertainty. Consequently, the evidences of uncertainty found are classified in a spectrum between statistical uncertainty and total ignorance (levels of uncertainty). Graphs and data are described to provide detailed information. The results signal predominant environmental uncertainty besides the uncertainty within control and supply of the closed-loop. A conclusion on the investigation shows cobalt as a raw material responsible for increasing uncertainty (boomerang effect). Additionally, the content analysis evidences uncertainty with the availability, quantity, stock control policies, government regulations, and political instability with cobalt, lithium, and nickel.publishersversionpublishe

    Influence of Aerobic Training on the Reduced Vasoconstriction to Angiotensin II in Rats Exposed to Intrauterine Growth Restriction: Possible Role of Oxidative Stress and AT(2) Receptor of Angiotensin II

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    Intrauterine growth restriction (IUGR) is associated with impaired vascular function, which contributes to the increased incidence of chronic disease. the aim of this study was to investigate whether aerobic training improves AngII-induced vasoconstriction in IUGR rats. Moreover, we assess the role of superoxide dismutase (SOD) isoforms and NADPH oxidase-derived superoxide anions in this improvement. Female Wistar rats were randomly divided into two groups on day 1 of pregnancy. A control group was fed standard chow ad libitum, and a restricted group was fed 50% of the ad libitum intake throughout gestation. At 8 weeks of age, male offspring from both groups were randomly assigned to 4 experimental groups: sedentary control (SC), trained control (TC), sedentary restricted (SRT), and trained restricted (TRT). the training protocol was performed on a treadmill and consisted of a continuous 60-min session 5 days/week for 10 weeks. Following aerobic training, concentration-response curves to AngII were obtained in endothelium-intact aortic rings. Protein expression of SOD isoforms, AngII receptors and the NADPH oxidase component p47(phox) was assessed by Western blot analysis. the dihydroethidium was used to evaluate the in situ superoxide levels under basal conditions or in the presence of apocynin, losartan or PD 123,319. Our results indicate that aerobic training can prevent IUGR-associated increases in AngII-dependent vasoconstriction and can restore basal superoxide levels in the aortic rings of TRT rats. Moreover, we observed that aerobic training normalized the increased p47(phox) protein expression and increased MnSOD and AT(2) receptor protein expression in thoracic aortas of SRT rats. in summary, aerobic training can result in an upregulation of antioxidant defense by improved of MnSOD expression and attenuation of NADPH oxidase component p47(phox). These effects are accompanied by increased expression of AT(2) receptor, which provide positive effects against Ang II-induced superoxide generation, resulting in attenuation of AngII-induced vasoconstriction.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Federal de São Paulo, Sch Med, Div Nephrol, São Paulo, BrazilUniv São Paulo, Dept Pharmacol, São Paulo, BrazilUniv São Paulo, Dept Physiol, São Paulo, BrazilUniversidade Federal de São Paulo, Sci & Technol Inst, São Paulo, BrazilUniversidade Federal de São Paulo, Sch Med, Dept Physiol, São Paulo, BrazilUniversidade Federal de São Paulo, Sch Med, Div Nephrol, São Paulo, BrazilUniversidade Federal de São Paulo, Sci & Technol Inst, São Paulo, BrazilUniversidade Federal de São Paulo, Sch Med, Dept Physiol, São Paulo, BrazilFAPESP: 2007/58044-2FAPESP: 2010/51904-9Web of Scienc

    Climate change and impact on renewable energies in the Azores strategic visions for sustainability

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    The energy sector is the largest contributor to global greenhouse gas emissions, but could also be seriously affected by climate change, calling into question society’s current consumption patterns. In this communication, climate projections based on a set of numerical models of global circulation are used to simulate the climate until the end of the century and keep in mind the alternative scenarios of pollutant emissions. Apart from solar energy, the results for the Azores region show a negative impact on the production and consumption of renewable energies. In the regional context, this issue assumes special relevance, given the geographical constraints, such as territorial discontinuity and insularity. Based on these assumptions, measures and recommendations are pointed out for the sectors that most penalize greenhouse gas emissions, considering the energy sustainability in the Azores and the commitments and goals assumed under international agreements.info:eu-repo/semantics/publishedVersio

    Organizational Practices for Learning with work accidents

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    O SHO 2010, Colóquio Internacional de Segurança e Higiene OcupacionaAs estatísticas europeias revelam que os acidentes de trabalho representam ainda um problema social importante para a nossa sociedade (Comissão Europeia, 2004) e, ao mesmo tempo, tem sido reconhecida a necessidade de usar a informação dos acidentes para a prevenção, através da aprendizagem (p. ex., Koornneef, 2000; Toft & Reynolds, 1997). O enfoque na aprendizagem salienta a necessidade de se ter informação disponível, disseminada, discutida, e mudanças implementadas. De acordo com Reason (1997) a aprendizagem decorre ao longo de um ciclo que começa com a observação de um acontecimento e termina com a acção que permite evitar a sua repetição. Até à data foram realizados poucos estudos que tenham abrangido todo o processo e etapas da aprendizagem ao longo do ciclo. O presente estudo visa contribuir para o aumento da compreensão sobre o modo como as empresas estão a usar a informação dos acidentes de trabalho para o desenvolvimento de estratégias e práticas de aprendizagem, tendo em consideração todas as fases do ciclo. Realizaram-se dezassete estudos de caso com organizações portuguesas que operam em diferentes sectores de actividade que foram identificadas como tendo “boas práticas”.Os dados foram recolhidos por meio de entrevistas semi- estruturadas realizadas com pessoas-chave na área da Segurança e/ou Recursos Humanos. Os resultados sugerem que as organizações estudadas têm alguns procedimentos bem definidos para a recolha, registo, codificação e análise de informações de acidentes. Simultaneamente, observa-se que alguns procedimentos são caracterizados pela não-padronização. Palavras-chave: apEuropean statistics show that accidents at work are still a major social problem for our society (European Commission, 2004) and at the same time, it has been recognized the need to use the information for accident prevention through learning (eg., Koornneef, 2000; Toft & Reynolds, 1997). The focus on learning emphasizes the need to have information available, disseminated, discussed, and changes need to be implemented. According to Reason (1997) learning takes place over a cycle that begins with the observation of an event and ends with action to prevent its recurrence. To date few studies have been conducted that have covered the whole process and stages of learning throughout the cycle. This study aims to contribute to increased understanding of how companies are using the information on accidents at work to develop strategies and practices of learning, taking into account all phases of the cycle. Seventeen case studies were conducted within Portuguese organizations from different activity sectors that have been identified as having "good practice". Data were collected through semi-structured interviews with key people in the area of safety and/or Human Resources Management. The results suggest that the organizations studied have some well-defined procedures for the collection, recording, coding and analysis of accidents. Simultaneously, we observed that some procedures are characterized by nonstandardization

    Trypsin purification using magnetic particles of azocasein-iron composite

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    This work presents an inexpensive, simple and fast procedure to purify trypsin based on affinity binding with ferromagnetic particles of azocasein composite (mAzo). Crude extract was obtained from intestines of fish Nile tilapia (Oreochromis niloticus) homogenized in buffer (01 g tissue/ml). This extract was exposed to 100mg of mAzo and washed to remove unbound proteins by magnetic field. Trypsin was leached off under high ionic strength (3 M NaCl). Preparation was achieved containing specific activity about 60 times higher than that of the crude extract. SDS-PAGE showed that the purified protein had molecular weight (24 kDa) in concordance with the literature for the Nile tilapia trypsin. The mAzo composite can be reused and applied to purify trypsin from other sources.Authors are thankful to CNPq (grant 307273/2013-0) and CAPES (Scholarship to MHMEA) Brazil agencies as well as FCT (Scholarship to SICS and CN) Portugal Agencie

    Leptin Downregulates LPS-Induced Lung Injury: Role of Corticosterone and Insulin

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    Background/Aims: We investigated the effects of leptin in the development of lipopolysaccharide (LPS)-induced acute lung inflammation (ALI) in lean mice. Methods: Mice were administered leptin (1.0 mu g/g) or leptin (1.0 mu g/g) followed by LPS (1.5 mu g/g) intranasally. Additionally, some animals were given LPS (1.5 mu g/g) or saline intranasally alone, as a control. Tissue samples and fluids were collected six hours after instillation. Results: We demonstrated that leptin alone did not induce any injury. Local LPS exposure resulted in significant acute lung inflammation, characterized by a substantial increase in total cells, mainly neutrophils, in bronchoalveolar lavages (BAL). We also observed a significant lymphocyte influx into the lungs associated with enhanced lung expression of chemokines and cytokines (KC, RANTES, TNF-alpha, IFN-beta, GM-CSF and VEGF). LPS-induced ALI was characterized by the enhanced expression of ICAM-1 and iNOS in the lungs. Mice that received LPS showed an increase in insulin levels. Leptin, when administered prior to LPS instillation, abolished all of these effects. LPS induced an increase in corticosterone levels, and leptin potentiated this event. Conclusion: These data suggest that exogenous leptin may promote protection during sepsis, and downregulation of the insulin levels and upregulation of corticosterone may be important mechanisms in the amelioration of LPS-induced ALI.Copyright (c) 2014 S. Karger AG, BaselConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Complex Fluids INCTFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Univ São Paulo, Inst Biomed Sci 1, Dept Pharmacol, Lab Hypertens, BR-1524 São Paulo, BrazilUniv São Paulo, Inst Biomed Sci, Dept Immunol, Lab Transplantat Immunobiol, BR-1524 São Paulo, BrazilUniv São Paulo, Lab Inflammat & Vasc Pharmacol, BR-05508 São Paulo, BrazilUniversidade Federal de São Paulo, Div Nephrol, Lab Clin & Expt Immunobiol, São Paulo, BrazilUniversidade Federal de São Paulo, Div Nephrol, Lab Clin & Expt Immunobiol, São Paulo, BrazilFAPESP: 12/51104-8FAPESP: 10/01404-0FAPESP: 12/02270-2FAPESP: 12/10512-6Web of Scienc

    Organizational Practices for Learning with work accidents

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    O SHO 2010, Colóquio Internacional de Segurança e Higiene OcupacionaAs estatísticas europeias revelam que os acidentes de trabalho representam ainda um problema social importante para a nossa sociedade (Comissão Europeia, 2004) e, ao mesmo tempo, tem sido reconhecida a necessidade de usar a informação dos acidentes para a prevenção, através da aprendizagem (p. ex., Koornneef, 2000; Toft & Reynolds, 1997). O enfoque na aprendizagem salienta a necessidade de se ter informação disponível, disseminada, discutida, e mudanças implementadas. De acordo com Reason (1997) a aprendizagem decorre ao longo de um ciclo que começa com a observação de um acontecimento e termina com a acção que permite evitar a sua repetição. Até à data foram realizados poucos estudos que tenham abrangido todo o processo e etapas da aprendizagem ao longo do ciclo. O presente estudo visa contribuir para o aumento da compreensão sobre o modo como as empresas estão a usar a informação dos acidentes de trabalho para o desenvolvimento de estratégias e práticas de aprendizagem, tendo em consideração todas as fases do ciclo. Realizaram-se dezassete estudos de caso com organizações portuguesas que operam em diferentes sectores de actividade que foram identificadas como tendo “boas práticas”.Os dados foram recolhidos por meio de entrevistas semi- estruturadas realizadas com pessoas-chave na área da Segurança e/ou Recursos Humanos. Os resultados sugerem que as organizações estudadas têm alguns procedimentos bem definidos para a recolha, registo, codificação e análise de informações de acidentes. Simultaneamente, observa-se que alguns procedimentos são caracterizados pela não-padronização. Palavras-chave: apEuropean statistics show that accidents at work are still a major social problem for our society (European Commission, 2004) and at the same time, it has been recognized the need to use the information for accident prevention through learning (eg., Koornneef, 2000; Toft & Reynolds, 1997). The focus on learning emphasizes the need to have information available, disseminated, discussed, and changes need to be implemented. According to Reason (1997) learning takes place over a cycle that begins with the observation of an event and ends with action to prevent its recurrence. To date few studies have been conducted that have covered the whole process and stages of learning throughout the cycle. This study aims to contribute to increased understanding of how companies are using the information on accidents at work to develop strategies and practices of learning, taking into account all phases of the cycle. Seventeen case studies were conducted within Portuguese organizations from different activity sectors that have been identified as having "good practice". Data were collected through semi-structured interviews with key people in the area of safety and/or Human Resources Management. The results suggest that the organizations studied have some well-defined procedures for the collection, recording, coding and analysis of accidents. Simultaneously, we observed that some procedures are characterized by nonstandardization

    Adenosine inhibits human astrocyte proliferation independently of adenosine receptor activation

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    Brain adenosine concentrations can reach micromolar concentrations in stressful situations such as stroke, neurodegenerative diseases or hypoxic regions of brain tumours. Adenosine can act by receptor-independent mechanism by reversing the reaction catalysed by S-adenosylhomocysteine (SAH) hydrolase, leading to SAH accumulation and inhibition of S-adenosylmethionine (SAM)-dependent methyltransferases. Astrocytes are essential in maintaining brain homeostasis but their pathological activation and uncontrolled proliferation plays a role in neurodegeneration and glioma. Adenosine can affect cell proliferation, but the effect of increased adenosine concentration on proliferation of astrocytes is not clarified and was addressed in present work. Human astrocytes (HA) were treated for 3 days with test drugs. Cell proliferation/viability was assessed by the MTT assay and by cell counting. Cell death was evaluated by assessing lactate dehydrogenase (LDH) release and by western blot analysis of αII-Spectrin cleavage. 30µM-Adenosine caused a 40%±3% (p < .05, n = 5) reduction in cell proliferation/viability, an effect reversed by 2U/ml-adenosine deaminase, but unchanged in the presence of antagonists of any of the adenosine receptors. Adenosine alone did not induce cell death. 100µM-Homocysteine alone caused 16%±3% (p < .05) decrease in HA proliferation. Combined action of adenosine and homocysteine decreased HA proliferation by 76%±4%, an effect higher (p < .05) than the sum of the effect of adenosine and homocysteine alone (56%±5%). The inhibitory effect of adenosine on HA proliferation/viability was mimicked by two adenosine kinase inhibitors and attenuated in the presence of folate (100µM) or SAM (50-100µM). The results suggest that adenosine reduces HA proliferation by a receptor-independent mechanism probably involving reversal of SAH hydrolase-catalysed reaction.info:eu-repo/semantics/acceptedVersio

    Upregulation of ERK1/2-eNOS via AT2 Receptors Decreases the Contractile Response to Angiotensin II in Resistance Mesenteric Arteries from Obese Rats

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    It has been clearly established that mitogen-activated protein kinases (MAPKS) are important mediators of angiotensin II (Ang II) signaling via AT1 receptors in the vasculature. However, evidence for a role of these kinases in changes of Ang II-induced vasoconstriction in obesity is still lacking. Here we sought to determine whether vascular MAPKs are differentially activated by Ang II in obese animals. the role of AT2 receptors was also evaluated. Male monosodium glutamate-induced obese (obese) and non-obese Wistar rats (control) were used. the circulating concentrations of Ang I and Ang II, determined by HPLC, were increased in obese rats. Ang II-induced isometric contraction was decreased in endothelium-intact resistance mesenteric arteries from obese compared with control rats and exhibited a retarded AT1 receptor antagonist response. Blocking of AT2 receptors and inhibition of either endothelial nitric oxide synthase (eNOS) or extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) restored Ang II-induced contraction in obese rats. Western blot analysis revealed increased protein expression of AT2 receptors in arteries from obese rats. Basal and Ang II-induced ERK1/2 phosphorylation was also increased in obese rats. Blockade of either AT1 or AT2 receptors corrected the increased ERK1/2 phosphorylation in arteries from obese rats to levels observed in control preparations. Phosphorylation of eNOS was increased in obese rats. Incubation with the ERK1/2 inhibitor before Ang II stimulation did not affect eNOS phosphorylation in control rats; however, it corrected the increased phosphorylation of eNOS in obese rats. These results clearly demonstrate that enhanced AT2 receptor and ERK1/2-induced, NO-mediated vasodilation reduces Ang II-induced contraction in an endothelium-dependent manner in obese rats.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Univ São Paulo, Inst Biomed Sci, Dept Pharmacol, São Paulo, BrazilUniv Fed Goias, Div Cardiovasc Physiol, Dept Biol Sci, Jatai, BrazilUniversidade Federal de São Paulo, Div Nephrol, Dept Med, Escola Paulista Med, São Paulo, BrazilUniversidade Federal de São Paulo, Div Nephrol, Dept Med, Escola Paulista Med, São Paulo, BrazilFAPESP: 2007/58311-0FAPESP: 2008/51622-3FAPESP: 2010/03642-5Web of Scienc
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