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Search Results: 1 - 10 of 144461 matches for " F. Frassetto "
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Single-Grating Monochromators for Extreme-Ultraviolet Ultrashort Pulses
Luca Poletto,Fabio Frassetto
Applied Sciences , 2013, DOI: 10.3390/app3010001
Abstract: A single-grating monochromator can be used for the spectral selection of ultrashort pulses without altering in a significant way the pulse duration, provided that the number of illuminated grooves is equal to the resolution. Two configurations are compared: the classical-diffraction mount (CDM) and the off-plane mount (OPM). The advantages and drawbacks of both configurations are presented. The two geometries can be joined in a new and innovative design of a monochromator with two interchangeable diffracting stages both used at grazing incidence, one with the gratings in the CDM and the other in the OPM. The use of two stages gives great flexibility: the OPM stage is used for sub-50 fs time response and low spectral resolution and the CDM stage for 100-200 fs time response and high spectral resolution. The design overcomes the limits of the two single configurations, giving on the same instrument either ultrafast response with low spectral resolution or slower response with higher resolution.
Ischemic preconditioning reduces peripheral oxidative damage associated with brain ischemia in rats
Frassetto S.S.,Schetinger M.R.C.,Webber A.,Sarkis J.J.F.
Brazilian Journal of Medical and Biological Research , 1999,
Abstract: Brain ischemia followed by reperfusion causes neuronal death related to oxidative damage. Furthermore, it has been reported that subjects suffering from ischemic cerebrovascular disorders exhibit changes in circulating platelet aggregation, a characteristic that might be important for their clinical outcome. In the present investigation we studied tert-butyl hydroperoxide-initiated plasma chemiluminescence and thiol content as measures of peripheral oxidative damage in naive and preconditioned rats submitted to forebrain ischemia produced by the 4-vessel occlusion method. Rats were submitted to 2 or 10 min of global transient forebrain ischemia followed by 60 min or 1, 2, 5, 10 or 30 days of reperfusion. Preconditioned rats were submitted to a 10-min ischemic episode 1 day after a 2-min ischemic event (2 + 10 min), followed by 60 min or 1 or 2 days of reperfusion. It has been demonstrated that such preconditioning protects against neuronal death in rats and gerbils submitted to a lethal (10 min) ischemic episode. The results show that both 2 and 10 min of ischemia cause an increase of plasma chemiluminescence when compared to control and sham rats. In the 2-min ischemic group, the effect was not present after reperfusion. In the 10-min ischemic group, the increase was present up to 1 day after recirculation and values returned to control levels after 2 days. However, rats preconditioned to ischemia (2 + 10 min) and reperfusion showed no differences in plasma chemiluminescence when compared to controls. We also analyzed plasma thiol content since it has been described that sulfhydryl (SH) groups significantly contribute to the antioxidant capacity of plasma. There was a significant decrease of plasma thiol content after 2, 10 and 2 + 10 min of ischemia followed by reperfusion when compared to controls. We conclude that ischemia may cause, along with brain oxidative damage and cell death, a peripheral oxidative damage that is reduced by the preconditioning phenomenon.
Ischemic preconditioning reduces peripheral oxidative damage associated with brain ischemia in rats
Frassetto, S.S.;Schetinger, M.R.C.;Webber, A.;Sarkis, J.J.F.;Netto, C.A.;
Brazilian Journal of Medical and Biological Research , 1999, DOI: 10.1590/S0100-879X1999001000017
Abstract: brain ischemia followed by reperfusion causes neuronal death related to oxidative damage. furthermore, it has been reported that subjects suffering from ischemic cerebrovascular disorders exhibit changes in circulating platelet aggregation, a characteristic that might be important for their clinical outcome. in the present investigation we studied tert-butyl hydroperoxide-initiated plasma chemiluminescence and thiol content as measures of peripheral oxidative damage in naive and preconditioned rats submitted to forebrain ischemia produced by the 4-vessel occlusion method. rats were submitted to 2 or 10 min of global transient forebrain ischemia followed by 60 min or 1, 2, 5, 10 or 30 days of reperfusion. preconditioned rats were submitted to a 10-min ischemic episode 1 day after a 2-min ischemic event (2 + 10 min), followed by 60 min or 1 or 2 days of reperfusion. it has been demonstrated that such preconditioning protects against neuronal death in rats and gerbils submitted to a lethal (10 min) ischemic episode. the results show that both 2 and 10 min of ischemia cause an increase of plasma chemiluminescence when compared to control and sham rats. in the 2-min ischemic group, the effect was not present after reperfusion. in the 10-min ischemic group, the increase was present up to 1 day after recirculation and values returned to control levels after 2 days. however, rats preconditioned to ischemia (2 + 10 min) and reperfusion showed no differences in plasma chemiluminescence when compared to controls. we also analyzed plasma thiol content since it has been described that sulfhydryl (sh) groups significantly contribute to the antioxidant capacity of plasma. there was a significant decrease of plasma thiol content after 2, 10 and 2 + 10 min of ischemia followed by reperfusion when compared to controls. we conclude that ischemia may cause, along with brain oxidative damage and cell death, a peripheral oxidative damage that is reduced by the preconditioning phenomenon.
Fully-tunable femtosecond laser source in the ultraviolet spectral range
B. Mahieu,S. Coraggia,C. Callegari,M. Coreno,G. De Ninno,M. Devetta,F. Frassetto,D. Garzella,M. Negro,C. Spezzani,C. Vozzi,S. Stagira,L. Poletto
Physics , 2011,
Abstract: We demonstrate experimentally the full tunability of a coherent femtosecond source in the whole ultraviolet spectral region. The experiment relies on the technique of high-order harmonic generation driven by a near-infrared parametric laser source in krypton gas. By tuning the drive wavelength in the range between 1100 to 1900 nm, we generated intense harmonics from near to extreme ultraviolet. A number of photons per shot of the order of 10^7 has been measured for the first harmonic orders. Many novel scientific prospects are expected to benefit from the use of such a table-top tunable source.
Aspectos da leptina na anorexia nervosa: possíveis efeitos benéficos no tratamento da hiperatividade
Frassetto, Silvana Soriano;Bitencourt, Graziela Oliveira de;
Revista de Nutri??o , 2009, DOI: 10.1590/S1415-52732009000500014
Abstract: recent studies have demonstrated a direct relationship between leptin and the regulation of energy balance, and as a factor involved in eating disorders. acting on the central nervous system, leptin affects food intake, glucose metabolism, body weight, the production of sexual hormones, and physical activity. studies with humans and animals indicate that low leptin levels are related to symptoms of anorexia nervosa: low food intake, excessive loss of body weight, amenorrhea and hyperactivity. thus, the degree of hypoleptinemia is not only a strong indication of low reserves of adipose tissue, but also of a severe disorder, and leptin levels can be used to better evaluate the seriousness of the disease. research has aimed to study the use of leptin in the treatment of patients with an, and positive results have been obtained in the reduction of hyperactivity. it is possible that leptin treatment associated with medication and psychotherapy can be beneficial for extremely active anorexia nervosa patients, making them more susceptible to further treatment. adequate food intake, medication, psychotherapy, and a comfortable environment during leptin treatment should be ensured. thus, this article aims to describe leptin and aspects related to anorexia, and discuss how this information can be important in the clinical evaluation of patients with this eating disorder.
Brain ischemia alters platelet ATP diphosphohydrolase and 5'-nucleotidase activities in naive and preconditioned rats
Frassetto, S.S.;Schetinger, M.R.C.;Schierholt, R.;Webber, A.;Bonan, C.D.;Wyse, A.T.;Dias, R.D.;Netto, C.A.;Sarkis, J.J.F.;
Brazilian Journal of Medical and Biological Research , 2000, DOI: 10.1590/S0100-879X2000001100017
Abstract: the effects of transient forebrain ischemia, reperfusion and ischemic preconditioning on rat blood platelet atp diphosphohydrolase and 5'-nucleotidase activities were evaluated. adult wistar rats were submitted to 2 or 10 min of single ischemic episodes, or to 10 min of ischemia 1 day after a 2-min ischemic episode (ischemic preconditioning) by the four-vessel occlusion method. rats submitted to single ischemic insults were reperfused for 60 min and for 1, 2, 5, 10 and 30 days after ischemia; preconditioned rats were reperfused for 60 min 1 and 2 days after the long ischemic episode. brain ischemia (2 or 10 min) inhibited atp and adp hydrolysis by platelet atp diphosphohydrolase. on the other hand, amp hydrolysis by 5'-nucleotidase was increased after 2, but not 10, min of ischemia. ischemic preconditioning followed by 10 min of ischemia caused activation of both enzymes. variable periods of reperfusion distinctly affected each experimental group. enzyme activities returned to control levels in the 2-min group. however, the decrease in atp diphosphohydrolase activity was maintained up to 30 days of reperfusion after 10-min ischemia. 5'-nucleotidase activity was decreased 60 min and 1 day following 10-min ischemia; interestingly, enzymatic activity was increased after 2 and 5 days of reperfusion, and returned to control levels after 10 days. ischemic preconditioning cancelled the effects of 10-min ischemia on the enzymatic activities. these results indicate that brain ischemia and ischemic preconditioning induce peripheral effects on ecto-enzymes from rat platelets involved in nucleotide metabolism. thus, atp, adp and amp degradation and probably the generation of adenosine in the circulation may be altered, leading to regulation of microthrombus formation since adp aggregates platelets and adenosine is an inhibitor of platelet aggregation.
CITIUS: an IR-XUV light source for fundamental and applied ultrafast science
C. Grazioli,C. Callegari,A. Ciavardini,M. Coreno,F. Frassetto,D. Gauthier,D. Golob,R. Ivanov,A. Kivim?ki,B. Mahieu,Bojan Bucar,M. Merhar,P. Miotti,L. Poletto,E. Polo,B. Ressel,C. Spezzani,G. De Ninno
Physics , 2013, DOI: 10.1063/1.4864298
Abstract: We present the main features of CITIUS, a new light source for ultrafast science, generating tunable, intense, femtosecond pulses in the spectral range from IR to XUV. The XUV pulses (about 10^5-10^8 photons/pulse in the range 14-80 eV) are produced by laser-induced high-order harmonic generation in gas. This radiation is monochromatized by a time-preserving monochromator, allowing also to work with high-resolution bandwidth selection. The tunable IR-UV pulses (10^{12}-10^{15} photons/pulse in the range 0.4-5.6 eV) are generated by an optical parametric amplifier, which is driven by a fraction of the same laser pulse that generates high order harmonics. The IR-UV and XUV pulses follow different optical paths and are eventually recombined on the sample for pump-probe experiments. The new light source will become the fulcrum of a new center located at the University of Nova Gorica, active in a wide range of scientific fields, including materials science, catalysis, biochemistry and magnetism. We also present the results of two pump-probe experiments: with the first one, we fully characterized the temporal duration of harmonic pulses in the time-preserving configuration; with the second one, we demonstrated the possibility of using CITIUS for studying of ultra-fast dynamics.
Possible observation of parametrically amplified coherent phasons in K0.3MoO3 using time-resolved extreme-ultraviolet ARPES
H. Y. Liu,I. Gierz,J. C. Petersen,S. Kaiser,A. Simoncig,A. L. Cavalieri,C. Cacho,I. C. E. Turcu,E. Springate,F. Frassetto,L. Poletto,S. S. Dhesi,Z. -A. Xu,T. Cuk,R. Merlin,A. Cavalleri
Physics , 2012, DOI: 10.1103/PhysRevB.88.045104
Abstract: We use time- and angle-resolved photoemission spectroscopy (tr-ARPES) in the Extreme Ultraviolet (EUV) to measure the time- and momentum-dependent electronic structure of photo-excited K0.3MoO3. Prompt depletion of the Charge Density Wave (CDW) condensate launches coherent oscillations of the amplitude mode, observed as a 1.7-THz-frequency modulation of the bonding band position. In contrast, the anti-bonding band oscillates at about half this frequency. We attribute these oscillations to coherent excitation of phasons via parametric amplification of phase fluctuations.
Leiomyosarcoma of Pulmonary Vein Presenting as Left Atrial Mass: An Outline of Management Principles
Philemon Gukop,Guido Frassetto,Georgios Karapanagiotidis,Venkatachalam Chandrasekaran
Case Reports in Cardiology , 2012, DOI: 10.1155/2012/396319
Abstract: Leiomyosarcoma of the pulmonary vein is rare and has poor prognosis. Its clinical features are nonspecific and mimic benign conditions. Early diagnosis is challenging. Most cases have been diagnosed only at autopsy or on postoperative histology specimens. Treatment is essentially palliative complete surgical excision. We outline the principles of management with the case of a 39-year-old man with leiomyosarcoma of the left pulmonary veins extending into the left atrium. Extensive investigation to achieve early diagnosis and determine extent of disease is essential. Frozen section guided adequate excision of all cardiac tumours and resection of involved lung tissue achieve local disease control. Adjuvant chemoradiotherapy has been shown to enhance survival.
Corre o de defeito ósseo femural em c es utilizando implante cortical homólogo conservado em mel
Amendola Gustavo Frassetto,Ilha Márcia,Berger Raquel,Stedile Rafael
Acta Cirurgica Brasileira , 2003,
Abstract: OBJETIVO: Avaliar a utiliza o de osso canino conservado em mel como implante em defeitos ósseos criados em fêmures de c es. MéTODOS: Doze caninos adultos foram submetidos a remo o de um segmento ósseo retangular compreendendo um ter o do diametro do osso por 2cm de comprimento da diáfise femural. Posteriormente foram inseridos dois pinos intramedulares e fixado um implante ósseo conservado de tamanho compatível com o defeito através de cerclagem com fio de a o. Os animais foram avaliados radiograficamente no dia da interven o cirúrgica e aos 30 e 60 dias. RESULTADOS: Após o final dos 60 dias foi possível verificar incorpora o do implante em oito animais enquanto que em quatro houve reabsor o do material implantado. CONCLUS O: O mel pode ser adequado como conservante de ossos.
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