Modeling and simulation results of a pulse skipping modulated buck converter for applications involving a source with widely varying voltage conditions with loads requiring constant voltage from full load down to no l...Modeling and simulation results of a pulse skipping modulated buck converter for applications involving a source with widely varying voltage conditions with loads requiring constant voltage from full load down to no load is presented. The pulses applied to the switch are blocked or released on output voltage crossing a predetermined value. The regulator worked satisfactorily over a wide input voltage range with good transient response but with higher ripple content. Input current spectrum indicates a good EMI performance with crowding of components at audio frequency range for the se-lected switching frequency.展开更多
Objective: To study mechanisms by which human gliomas may escape immune surveillance Methods: The effect of supernatant (SN) obtained from cultured media of malignant glioma cell lines on the proliferation of phyto...Objective: To study mechanisms by which human gliomas may escape immune surveillance Methods: The effect of supernatant (SN) obtained from cultured media of malignant glioma cell lines on the proliferation of phytohemagglutinin p stimulated peripheral blood lymphocytes (PBLs) from healthy subjects and patients with gliomas was examined by MTT assay The immunosuppressive factor which might be existed in the SN was identified by neutralization method with specific antibodies and Northern blot hybridization of glioma cells In addition, the cellular immunity of patients with gliomas and relevant hormone and catecholamine were determined Results: It was found that the malignant glioma cells could release an immunosuppressive factor in an autocrine fashion which was further identified as the transforming growth factor β 2 (TGF β 2) It was also demonstrated that the plasma levels of norepinephrine in glioma patients were significantly reduced and correlated well with the suppression of the patients' own cellular immunity Conclusions: Two distinct mechanisms by which human gliomas may evade immune surveillance: 1 The secretion of an immunosuppressive factor which was identified as TGF β 2; 2 The dysfunction of Neuro Immune modulation in the presence of cerebral gliomas展开更多
文摘Modeling and simulation results of a pulse skipping modulated buck converter for applications involving a source with widely varying voltage conditions with loads requiring constant voltage from full load down to no load is presented. The pulses applied to the switch are blocked or released on output voltage crossing a predetermined value. The regulator worked satisfactorily over a wide input voltage range with good transient response but with higher ripple content. Input current spectrum indicates a good EMI performance with crowding of components at audio frequency range for the se-lected switching frequency.
文摘Objective: To study mechanisms by which human gliomas may escape immune surveillance Methods: The effect of supernatant (SN) obtained from cultured media of malignant glioma cell lines on the proliferation of phytohemagglutinin p stimulated peripheral blood lymphocytes (PBLs) from healthy subjects and patients with gliomas was examined by MTT assay The immunosuppressive factor which might be existed in the SN was identified by neutralization method with specific antibodies and Northern blot hybridization of glioma cells In addition, the cellular immunity of patients with gliomas and relevant hormone and catecholamine were determined Results: It was found that the malignant glioma cells could release an immunosuppressive factor in an autocrine fashion which was further identified as the transforming growth factor β 2 (TGF β 2) It was also demonstrated that the plasma levels of norepinephrine in glioma patients were significantly reduced and correlated well with the suppression of the patients' own cellular immunity Conclusions: Two distinct mechanisms by which human gliomas may evade immune surveillance: 1 The secretion of an immunosuppressive factor which was identified as TGF β 2; 2 The dysfunction of Neuro Immune modulation in the presence of cerebral gliomas
