1,638 research outputs found

    Tunnelling effect of charged and magnetized particles from the Kerr–Newman–Kasuya black hole

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    AbstractIn this Letter, we extend the Parikh–Wilczek tunnelling framework to calculate the emission rate of a particle with electric and magnetic charges. We first reconstruct the electromagnetic field tensor and the Lagrangian of the field corresponding to the source with electric and magnetic charges. Then, in the background of Kerr–Newman–Kasuya black hole spacetime, we calculate the emission spectrum of the outgoing particles with electric and magnetic charges. For the sake of simplicity, we only consider the case that the rate of electric and magnetic charge of the emission particle is constant and equals that of the black hole. In this case, the emission spectrum deviates from the pure thermal spectrum, but it is consistent with an underlying unitary theory and takes the same functional form as that of uncharged massless particles. Finally, discussions about the result are presented

    Separation of Different Contributions to the Total X-ray Luminosity in Gamma-ray Loud Blazars

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    The relativistic beaming model has been successfully used to explain many of the observational properties of active galactic nuclei. In this model the total emission is formed by two components, one beamed, one unbeamed. However, the exact contribution from each component in unresolved sources is still not clear. In the radio band, the core and extended emissions are clearly separated. We adopt the method proposed by Kembhavi to separate the two contributions in the X-ray emissions in a sample of 19 gamma-ray loud blazars. It is clearly shown that the beamed emission dominates the X-ray flux and the unbeamed X-ray emission is correlated with the extended radio emission of the considered objects. We also find that the ratio of the beamed to the unbeamed X-ray luminosity is correlated with the X-ray spectral index, an effect that should be a consequence of the underlying X-ray emission mechanism.Fil: Fan, Jun Hui. Guangzhou University. Center for Astrophysics; ChinaFil: Romero, Gustavo Esteban. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Wang, Yong Xiang. College of Science and Trade; ChinaFil: Zhang, Jiang Shui. Guangzhou University. Center for Astrophysics; Chin

    Beaming and precession in the inner jet of 3C273 II: the central engine

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    The quasar 3C 273 is a well-known superluminal source. More than 10 radio components have been detected moving away from the nucleus with different superluminal speeds and position angles. The pattern of ejection suggests the existence of a precessing inner jet, whose kinematics has been discussed by Abraham & Romero (1999). We now present a binary black hole model for the central engine of 3C 273 where the rapid precession is tidally induced in the primary accretion disk inner region by a secondary black hole in a non-coplanar orbit. Using γ- and X-ray data we estimate upper limits for the mass of the primary, and then we compute the relevant parameters of the system for a variety of disk models. We also discuss some of the implications of the model for the electromagnetic and gravitational radiation from 3C 273.Fil: Romero, Gustavo Esteban. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Chajet, L.. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Abraham, Zulema. Universidade de Sao Paulo; BrasilFil: Fan, Jun Hui. Guangzhou Normal University; Chin

    Beaming and precession in the inner jet of 3C 273 : II. The central engine

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    The quasar 3C 273 is a well-known superluminal source. More than 10 radio components have been detected moving away from the nucleus with different superluminal speeds and position angles. The pattern of ejection suggests the existence of a precessing inner jet, whose kinematics has been discussed by Abraham & Romero (1999). We now present a binary black hole model for the central engine of 3C 273 where the rapid precession is tidally induced in the primary accretion disk inner region by a secondary black hole in a non-coplanar orbit. Using γ- and X-ray data we estimate upper limits for the mass of the primary, and then we compute the relevant parameters of the system for a variety of disk models. We also discuss some of the implications of the model for the electromagnetic and gravitational radiation from 3C 273.Facultad de Ciencias Astronómicas y GeofísicasInstituto Argentino de Radioastronomí

    Video-assisted thoracoscopic surgery is more favorable than thoracotomy for administration of adjuvant chemotherapy after lobectomy for non-small cell lung cancer

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    <p>Abstract</p> <p>Background</p> <p>Video-assisted thoracoscopic surgery (VATS) lobectomy is a newly developed type of surgery for lung cancer and has been demonstrated obvious minimally-invasive advantages compared with traditional thoracotomy. Theoretically, that less trauma leads to quicker recovery and may facilitate administration of adjuvant chemotherapy. We tested this hypothesis in this study.</p> <p>Methods</p> <p>One hundred and ten NSCLC patients underwent lobectomy and adjuvant chemotherapy from June 2004 to June 2010 was analyzed. The baseline characteristic criteria, variables related to surgery and accomplishing status of chemotherapy were analyzed.</p> <p>Results</p> <p>All 110 patients underwent lobectomy through VATS (n = 54) or thracotomy (n = 56) and adjuvant chemotherapy. There was no significant difference in patients' age, preoperative pulmonary function, co-morbidity, pathologic staging between the two groups, whereas, blood loss, operation time and postoperative complications, chest tube duration and length of stay were less in VATS group. There were no significant differences in time to initiation chemotherapy. Cases in VATS group received more cycles of chemotherapy (3.6 vs. 3.0, p = 0.002). A higher proportion of patients received full dose on schedule in VATS group (57.4% vs. 33.9%, p = 0.013) and a higher proportion of patients completed ≥75% planed dose, (88.9% vs. 71.4%, p = 0.022); slightly higher proportion of patients in thoracotomy group had grade 3 or more toxicity (20.4% vs. 35.7%, p = 0.074).</p> <p>Conclusions</p> <p>Patients underwent lobectomy by VATS have better compliance and fewer delayed or reduced dose on adjuvant chemotherapy than those by thoracotomy.</p

    Overcoming the Circular Problem for \gamma-ray Bursts in Cosmological Global Fitting Analysis

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    Due to the lack of low redshift long Gamma-Ray Bursts (GRBs), the circular problem has been a severe obstacle for using GRBs as cosmological candles. In this paper, we present a new method to deal with such a problem in MCMC global fitting analysis. Assuming that a certain type of correlations between different observables exists in a subsample of GRBs, for the parameters involved in the correlation relation, we treat them as free parameters and determine them simultaneously with cosmological parameters through MCMC analysis on GRB data together with other observational data. Then the circular problem is naturally eliminated in this procedure. We take the Ghirlanda relation as an example while keeping in mind the debate about its physical validity. Together with SNe Ia, WMAP and SDSS data, we include 27 GRBs with the reported Ghirlanda relation in our study, and perform MCMC global fitting. We consider the Λ\LambdaCDM model and dynamical dark energy models. In each case, in addition to the constraints on the relevant cosmological parameters, we obtain the best fit values as well as the distributions of the correlation parameters AA and CC. We find that the observational data sets other than GRBs can affect AA and CC considerably through their degeneracies with the cosmological parameters. The results on AA and CC for different cosmological models are in well agreement within 1σ1\sigma range. The best fit value of AA in all models being analyzed is A∼1.53A\sim 1.53 with σ∼0.08\sigma \sim 0.08. For CC, we have the best value in the range of 0.94−0.980.94-0.98 with σ∼0.1\sigma\sim 0.1. It is also noted that the distributions of AA and CC are generally broader than the priors used in many studies in literature. (Abriged)Comment: 9 pages, 2 figures, 2 tables, Accepted for publication in Ap

    Anti-tumor effects of CIK combined with oxaliplatin in human oxaliplatin-resistant gastric cancer cells in vivo and in vitro

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    <p>Abstract</p> <p>Background</p> <p>Drug resistance remains a great challenge in the treatment of gastric cancer. The goal of this study was to explore the anti-tumor effects and mechanism of cytokine-induced killer (CIK) cell combined with oxaliplatin (L-OHP) in human oxaliplatin-resistant gastric cancer cells.</p> <p>Methods</p> <p>After producing oxaliplatin-resistant gastric cancer cells, cell morphology, growth and doubling time were observed, followed by detection of cell cycle distribution and apoptosis, drug sensitivity (e.g., L-OHP) and expression of P-gp and livin. MTT assay, in vivo pharmacodynamics and pathomorphology experiments were used to detect killing activities of CIK combined with L-OHP.</p> <p>Results</p> <p>Compared with parental gastric cancer cells, oxaliplatin-resistant gastric cancer cells in S phase were reduced and cell apoptosis rate was increased (P < 0.05), the inhibition rate of 10 chemotherapeutics on oxaliplatin-resistant gastric cancer cells was significantly lower and the expression of P-gp was significantly higher (P < 0.05). However, there was no significant difference in livin expression between parental gastric cancer cells and oxaliplatin-resistant gastric cancer cells (P > 0.05). The in vitro killing activity of CIK combined with L-OHP on parental cells and oxaliplatin-resistant cells were significantly enhanced compared with L-OHP or CIK alone. And it showed greater synergetic effects against oxaliplatin-resistant cells compared with parental cells (P < 0.05). In addition, survival rate, abdominal circumference and pathomorphology results revealed stronger in vivo anti-tumor effects when the two therapies were combined.</p> <p>Conclusions</p> <p>The mechanism of oxaliplatin-resistant cell secondary multidrug resistance was correlated with the variation of cell cycle distribution, extension of doubling time and upregulation of P-gp expression. The synergistic effect of CIK in combination with L-OHP on killing activity against oxaliplatin-resistant cells was shown in vivo and in vitro.</p
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