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Search Results: 1 - 10 of 593298 matches for " Léa Goldenstein "
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Léa Goldenstein,Manoel Seabra
Revista do Departamento de Geografia , 1982, DOI: 10.7154/rdg.v0i1.292
Efeitos do carbono na evolu??o de segundas-fases e na densifica??o do nitreto de alumínio com Y2O3
Molisani, A. L.;Goldenstein, H.;Yoshimura, H. N.;
Ceramica , 2010, DOI: 10.1590/S0366-69132010000400004
Abstract: the effect of carbon addition on the second-phases evolution and on the densification of aln with 4wt.%.y2o3 was investigated. the change of second-phase composition of aln with y2o3 was induced by the addition of 0.5wt.% and 1.0wt.% carbon. sintering under nitrogen atmosphere was performed in tungsten heated furnace between 1650 oc and 1850 oc. the second-phase evolution had a tendency to form y-richer phases with increasing carbon content, which delayed the densification of aln with y2o3 due to the increase of liquid-phase formation temperature. the harmful effect caused by the addition of carbon was diminished with increasing sintering temperature, since all samples achieved almost full densification after sintering at 1800 oc. the addition of carbon induced significant evaporation of compounds during sintering, but the densification behavior was little influenced by the reduction in liquid-phase fraction formed at sintering temperature or the entrapped gas inside the closed pores.
Efeito do teor de Y2O3 na sinteriza??o do nitreto de alumínio
Molisani, A. L.;Yoshimura, H. N.;Goldenstein, H.;
Ceramica , 2006, DOI: 10.1590/S0366-69132006000200006
Abstract: y2o3 is the main sintering aid for high thermal conductivity aln ceramics for the production of electronic devices. the effect of varying the amount of y2o3 as sintering aid for aln from 0.5 to 4 wt% was investigated. the effects of different amounts of y2o3 were correlated with results of density and microstructural analysis, as well as the evolution of second phases, as a function of sintering temperature. green bodies were sintered in nitrogen atmosphere using a tungsten element furnace, between 1650 and 2000 oc for 1 h. the results showed the densification of aln samples with y2o3 by solid state sintering up to 1700 oc; above this temperature, densification occurred by liquid-phase sintering. the melting of a yag phase caused the formation of liquid phase at around 1725 oc, in samples of aln with up to 4 wt% y2o3. the amount of liquid-phase increased with increasing sintering aid content only after the full densification of the samples, due to the melting of large refractory particles of yttrium aluminates (yap and yam) at high temperatures. as a result, the increase of the y2o3 content (0.5 to 4 wt%) did not cause significant variations in the densification behavior of the aln, as the amount of liquid-phase was similar for all temperatures in the range at which densification occurred. the addition of only 0.5 wt% y2o3 increased significantly the sinterability of aln. the use of y2o3 with large particle size distribution in relation to aln did not cause the formation of large pores. the results showed a trend towards oxide compounds evaporation in aln samples with y2o3, when sintered above 1850 oc.
Efeito da porosidade nas propriedades mecanicas de uma alumina de elevada pureza
Yoshimura, H. N.;Molisani, A. L.;Siqueira, G. R.;Camargo, A. C. de;Narita, N. E.;Cesar, P. F.;Goldenstein, H.;
Ceramica , 2005, DOI: 10.1590/S0366-69132005000300011
Abstract: a high purity alumina doped with mgo was sintered between 1300 and 1700 °c in order to prepare samples with different porosities. the following properties were determined: four-point flexural strength, fracture toughness, by sevnb method, vickers hardness, (transversal and longitudinal) sonic velocities, and elastic constant (n, e, g e k), by ultrasonic pulse-echo method. the results were compared with models based on stress concentration (sc) and models based on minimum solid area (msa). the porosity of the samples varied between 0.8% and 35%. generally, the properties lowered with increasing porosity. this lowering was weaker in sonic velocities and stronger in hardness. the poisson's ratio lowered only above 19% porosity. the analytical model (sc) which best fitted the results of e and g moduli was the hashin-rosen model for cylindrical pores aligned transversally to the applied stress. analysis by asm models indicated that, until 19% porosity, the model for spherical pores in cubic stacking was predominant and, above this porosity, the model for spherical particles in cubic stacking also acted.
Involvement of haptoglobin in prevention of oxidative stress cause by hemoglobin in preeclampsia  [PDF]
Hagit Goldenstein, Nina Levy, Andrew Levy
Advances in Bioscience and Biotechnology (ABB) , 2012, DOI: 10.4236/abb.2012.327126
Abstract: Haptoglobin (Hp) is a hemoglobin (Hb) binding protein which plays an important role in neutralizing oxidation reactions stimulated by heme-derived iron. Differences in Hp types due to the polymorphic nature of the gene have led to the discovery that individuals carrying the Hp 2-2 genotype are at increased risk of developing vascular complications in the setting of diabetes. Preeclampsia is a pregnancy related disease that is thought to be caused by increases in oxidative stress. The role of Hp polymorphism is determining preeclampsia has been addressed by several clinical studies but the results have been contradictory. Larger longitudinal studies are needed to answer this important question.
Increased Fas and Bcl-2 Expression on Peripheral Blood T and B Lymphocytes from Juvenile-Onset Systemic Lupus Erythematosus, but not from Juvenile Rheumatoid Arthritis and Juvenile Dermatomyositis
Bernadete L. Liphaus,Maria H. B. Kiss,Solange Carrasco,Claudia Goldenstein-Schainberg
Clinical and Developmental Immunology , 2006, DOI: 10.1080/17402520600877786
Abstract: Defective regulation of apoptosis may play a role in the development of autoimmune diseases. Fas and Bcl-2 proteins are involved in the control of apoptosis. The aims of this study were to determine the expression of Fas antigen and Bcl-2 protein on peripheral blood T and B lymphocytes from patients with juvenile-onset systemic lupus erythematosus (JSLE), juvenile rheumatoid arthritis (JRA) and juvenile dermatomyositis (JDM). Thirty-eight patients with JSLE, 19 patients with JRA, 10 patients with JDM and 25 healthy controls entered the study. Freshly isolated peripheral blood mononuclear cells (PBMC) were stained for lymphocyte markers CD3, CD4, CD8, CD19 and for Fas and Bcl-2 molecules. Expressions were measured by three-color flow cytometry. Statistical analysis was performed using Kruskal–Wallis test. Percentages of freshly isolated T lymphocytes positively stained for Fas protein from JSLE patients were significantly increased compared to healthy controls, patients with JRA and patients with JDM. Percentages of B lymphocytes positive for Fas from JSLE patients were higher than healthy controls and JRA patients. In addition, Fas expression on T cells from patients with JRA was increased compared to JDM patients. Otherwise, Fas expression on T and B cells from JRA and JDM patients were similar to healthy controls. MFI of Bcl-2 positive T lymphocytes from JSLE patients were significantly increased compared to healthy controls and JRA patients. MFI of Bcl-2 protein on B lymphocytes from JSLE patients was similar to healthy controls and patients with JRA and JDM. Bcl-2 expression did not differ between JRA and JDM patients and healthy controls. In conclusion, increased expression of Fas and Bcl-2 proteins observed in circulating T and B lymphocytes from patients with JSLE, but not from patients with JRA and JDM, suggests that abnormalities of apoptosis may be related to the pathogenesis of JSLE and probably are not a result of chronic inflammation.
Decreased high-density lipoprotein cholesterol levels in polyarticular juvenile idiopathic arthritis
Marangoni, Roberta Gon?alves;Hayata, Andre L;Borba, Eduardo F;Azevedo, Pedro M;Bonfá, Eloisa;Schainberg, Claudia Goldenstein;
Clinics , 2011, DOI: 10.1590/S1807-59322011000900007
Abstract: objectives: to investigate the prevalence of dyslipoproteinemia in a homogeneous cohort of polyarticular juvenile idiopathic arthritis patients. methods: based on the national cholesterol education program, fasting lipoprotein levels and risk levels for coronary artery disease were determined in 28 patients with polyarticular juvenile idiopathic arthritis. the exclusion criteria included diabetes, thyroid dysfunction, smoking, proteinuria, lipid-lowering drugs, and hormone/diuretic therapy. disease activity, disease duration, and therapy with corticosteroids and/or chloroquine were defined at the time of lipid measurements. results: dyslipoproteinemia was identified in 20 of the 28 (71%) patients with polyarticular juvenile idiopathic arthritis. the primary lipoprotein risk factor was decreased high-density lipoprotein cholesterol (57%), followed by elevated levels of low-density lipoprotein cholesterol (18%), triglycerides (14%), and total cholesterol (7%). the male patients had decreased high-density lipoprotein cholesterol levels than the female patients (p<0.05). the incidence of decreased high-density lipoprotein cholesterol levels did not seem to be affected by disease activity or therapy because the incidence was similar in patients with active or inactive disease, with or without corticosteroid use and with or without chloroquine use. in addition, the frequency of decreased high-density lipoprotein cholesterol levels was similar in patients with short (≤5 years) vs. long (>5 years) disease duration. conclusions: dyslipoproteinemia is highly prevalent in patients with polyarticular juvenile idiopathic arthritis and is primarily related to decreased high-density lipoprotein cholesterol levels; therefore, early intervention is essential.
Dermatomiosite juvenil: revis?o e atualiza??o em patogênese e tratamento
Rosa Neto, Nilton Salles;Goldenstein-Schainberg, Cláudia;
Revista Brasileira de Reumatologia , 2010, DOI: 10.1590/S0482-50042010000300010
Abstract: juvenile dermatomyositis (jdm) is an autoimmune disease characterized by systemic vasculopathy. its main manifestations include symmetrical proximal muscle weakness, elevated serum muscle enzymes and cutaneous lesions, among which the heliotrope and gottron's papules are pathognomonic. early recognition and prompt therapy allow better prognosis and prevent the development of calcinosis. although the treatment is based on glucocorticoids, the more commonly associated immunosuppressors include methotrexate, azathioprine, cyclosporine, and cyclophosphamide, depending on the severity of disease. the use of immunobiologicals for refractory cases remains under investigation, but the results are controversial or inexpressive. in this review, we highlight recent updates on the pathogenesis and treatment of jdm.
Conceitos atuais e relevantes sobre artrite psoriásica
Goldenstein-Schainberg, Claudia;Favarato, Maria Helena Sampaio;Ranza, Roberto;
Revista Brasileira de Reumatologia , 2012, DOI: 10.1590/S0482-50042012000100010
Abstract: psoriatic arthritis (psa) is a systemic, polymorphic joint disease with variable presentation and clinical course. the outcome depends on the association with severe comorbidities such as diabetes, hypertension and dyslipidemia. early diagnosis requires a high degree of clinical suspicion, especially when skin manifestations are subtle and poorly defined. progressive erosive disease can occur in up to half of patients, associated with anatomical and functional changes in about 20%. thus, the prognosis of psa remains unclear, especially if diagnosis and treatment are delayed. based on extensive literature review (pubmed and lilacs) and experience of our services, new concepts of immunogenetics, pathophysiology, and clinical and therapeutic aspects are discussed. factors that reduce the quality of life and life expectancy of patients, as well as new guidelines for treatment, will be emphasized. control of inflammation, especially in enthesitis and axial forms of psa, was made possible due to the introduction of anti-tnf biologics. finally, the role of grappa (group for research and assessment of psoriasis and psoriatic arthritis) should be emphasized, since it promotes meetings and joint studies between rheumatologists and dermatologists to provide scientific evidence for the sweeping changes in clinical management and treatment of patients with psa
An approach to the correlation of security events based on machine learning techniques
Kleber Stroeh, Edmundo Roberto Mauro Madeira and Siome Klein Goldenstein
Journal of Internet Services and Applications , 2013, DOI: 10.1186/1869-0238-4-7
Abstract: Organizations face the ever growing challenge of providing security within their IT infrastructures. Static approaches to security, such as perimetral defense, have proven less than effective ? and, therefore, more vulnerable ? in a new scenario characterized by increasingly complex systems and by the evolution and automation of cyber attacks. Moreover, dynamic detection of attacks through IDSs (Instrusion Detection Systems) presents too many false positives to be effective. This work presents an approach on how to collect and normalize, as well as how to fuse and classify, security alerts. This approach involves collecting alerts from different sources and normalizes them according to standardized structures ? IDMEF (Intrusion Detection Message Exchange Format). The normalized alerts are grouped into meta-alerts (fusion, or clustering), which are later classified using machine learning techniques into attacks or false alarms. We validate and report an implementation of this approach against the DARPA Challenge and the Scan of the Month, using three different classifications ? SVMs, Bayesian Networks and Decision Trees ? having achieved high levels of attack detection with little false positives. Our results also indicate that our approach outperforms other works when it comes to detecting new kinds of attacks, making it more suitable to a world of evolving attacks.
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