602 research outputs found

    Implicit Resolution

    Full text link
    Let \Omega be a set of unsatisfiable clauses, an implicit resolution refutation of \Omega is a circuit \beta with a resolution proof {\alpha} of the statement "\beta describes a correct tree-like resolution refutation of \Omega". We show that such system is p-equivalent to Extended Frege. More generally, let {\tau} be a tautology, a [P, Q]-proof of {\tau} is a pair (\alpha,\beta) s.t. \alpha is a P-proof of the statement "\beta is a circuit describing a correct Q-proof of \tau". We prove that [EF,P] \leq p [R,P] for arbitrary Cook-Reckhow proof system P

    Implicit Resolution

    Full text link

    Optical appearance of Einstein-{\AE}ther black hole surrounded by thin disk

    Full text link
    In Einstein-{\AE}ther theory, the Lorentz symmetry is locally broken in the high-energy regime due to the presence of the{\AE}ther field. This shall leave significant imprint on astronomical observation. In this paper, we investigate the optical appearance of two types of the static and spherically symmetric black holes in Einstein-{\AE}ther theory. Via Euler-Lagrange equation, we obtain the equations of motion of the photon and calculate the total deflection angle of the photon trajectory around the black hole. By classifying the light rays with the total number of orbits, we study the effects of coupling constants on the direct image, lensing ring, and photon ring. The features of the light trajectories are also investigated by comparing with the Einstein-{\AE}ther theory and general relativity. Moreover, we also show the explicit optical appearance of black holes surrounded by thin disk emissions with three characteristic emitted models. The results indicate that the direct image gives the main contribution to the total flux, and the lensing ring just gives a very small contribution, whereas the role of the photon ring is negligible. The optical appearances are also found to significantly rely on these coupling constants.Comment: 19 pages, 6 figure

    Effect of ligustrazine injection on the change of oxidative stress system during renal ischemia reperfusion injury in rabbits

    Get PDF
    目的  通过由兔肾脏缺血/再灌注损伤(IRI)导致的氧化应激体系中的变化,研究中药川芎嗪对IRI干预下的作用机制。方法  建立持续性阻断兔双侧肾动脉血流1h,再灌注5h的肾IRI动物模型。日本大耳兔32只,随机分成3组(n=10):假手术组(sham,S组),缺血/再灌注组(ischemia-reperfusion,IR组),川芎嗪干预缺血/再灌注组(ligustrazine+ ischemia-reperfusion,LZ组),另外两只作为补充实验中意外死亡之用。于缺血前、缺血1h、再灌注1h、3h和5h依次经颈总动脉抽血用以检测超氧化物歧化酶(SOD)活力、黄嘌呤氧化酶(XO)活力以及丙二醛(MDA)含量。在实验结束后取兔肾组织依次检测SOD、XO活力以及MDA含量,并对其进行电镜观察。结果  随着肾缺血和再灌注时间的增加,IR组和LZ组血浆中的XO活力和MDA含量逐渐呈上升趋势,但同时间点LZ组较于IR组明显降低(均P<0.01);SOD活力随着肾缺血和再灌注时间的增加而逐渐呈下降趋势,但同时间点下,LZ组较于IR组均明显偏高(均P<0.01)。IR组和LZ组相较于S组,肾组织XO活力、MDA含量均明显升高,SOD活力均明显降低(均P<0.01);而LZ组肾组织中的XO活力、MDA含量均显著低于IR组,SOD活力均显著高于IR组,差异有非常显著性(均P<0.01),LZ组肾组织细胞的超微结构异常改变较IR组显著减轻。结论  川芎嗪能够使氧自由基水平降低,氧化应激损伤减轻,具有保护肾缺血/再灌注损伤的作用。Objective: To investigate the change of oxidative stress system during renal ischemia-reperfusion injury, and to study the mechanism of Ligustrazine on IRI under the intervention. Methods: Establish the IRI animal model by persistent blocking rabbits’ bilateral renal artery blood flow for 1 hour, then reperfusion for another 5 hours. Japanese big ear rabbits, 32, were randomly divided into three groups (n=10): sham operation group (group S), ischemia/reperfusion group (group IR), the effect of ligustrazine on ischemia/ reperfusion group (LZ group), the other two being added in the experiment for accidental death. In 1 hour before ischemia, ischemia, reperfusion 1h, 3h and 5h in turn to check the enzyme activity of superoxide dismutase (SOD), xanthine oxidase (XO) and the content of malondialdehyde (MDA) by getting the blood from common carotid artery. At the end of the experiment, the rabbit’s kidney was used to check the enzyme activity of XO, SOD and the content of MDA, then to observe the morphological changes under the electron microscopy. Results: With the increase of renal ischemia and reperfusion time, XO activity and MDA content of IR group and LZ group in plasma gradually up, they were significantly lower in LZ group than in IR group at same time point (all P<0.01), the activity of SOD in plasma was shown a time-dependent decline in both IR group and LZ group, whereas it was significant higher in LZ group compared with IR group at same time point during ischemia reperfusion (all P<0.01). SOD activity gradually decreased with the increase of renal ischemia and reperfusion time, but at the same time point, LZ group compared with IR group were significantly higher (P<0.01), however, for LZ group, as compared with IR group, activity of XO, content of MDA were increased remarkably while activity of SOD was decreased significantly in kidney tissue (all P<0.01) the abnormal changes of ultrastructure were mitigated significantly. Conclusion: Ligustrazine may attenuate renal ischemia-reperfusion injury by dropping oxygen free radical generation and enhancing oxygen free radical scavenge so that it can antagonize oxidative stress
    corecore