分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: By considering the quantum Oppenheimer-Snyder model in loop quantum cosmology, a new quantum black hole model whose metric tensor is a suitably deformed Schwarzschild one is derived. The quantum effects imply a lower bound on the mass of the black hole produced by the collapsing dust ball. For the case of larger masses where the event horizon does form, the maximal extension of the spacetime and its properties are investigated. By discussing the opposite scenario to the quantum Oppenheimer-Snyder, a quantum Swiss Cheese model is obtained with a bubble surrounded by the quantum universe. This model is analogous to black hole cosmology or fecund universes where the big bang is related to a white hole. Thus our models open a new window to cosmological phenomenology.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: Given the non-graph-changing Hamiltonian $\widehat{H[N]}$ in Loop Quantum Gravity (LQG), $\langle\widehat{H[N]}\rangle$, the coherent state expectation value of $\widehat{H[N]}$, admits an semiclassical expansion in $\ell^2_{\rm p}$. In this paper, as presenting the detailed derivations of our previous work arXiv:2012.14242, we explicitly compute the expansion of $\langle\widehat{H[N]}\rangle$ to the linear order in $\ell^2_{\rm p}$ on the cubic graph with respect to the coherent state peaked at the homogeneous and isotropic data of cosmology. In our computation, a powerful algorithm is developed, supported by rigorous proofs and several theorems, to overcome the complexity in the computation of $\langle \widehat{H[N]} \rangle$. Particularly, some key innovations in our algorithm substantially reduce the complexity in computing the Lorentzian part of $\langle\widehat{H[N]}\rangle$. Additionally, some quantum correction effects resulting from $\langle\widehat{H[N]}\rangle$ in cosmology are discussed at the end of this paper.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: Given the Loop-Quantum-Gravity (LQG) non-graph-changing Hamiltonian $\widehat{H[N]}$, the coherent state expectation value $\langle\widehat{H[N]}\rangle$ admits an semiclassical expansion in $\ell^2_{\rm p}$. In this paper, we compute explicitly the expansion of $\langle\widehat{H[N]}\rangle$ on the cubic graph to the linear order in $\ell^2_{\rm p}$, when the coherent state is peaked at the homogeneous and isotropic data of cosmology. In our computation, a powerful algorithm is developed to overcome the complexity in computing $\langle \widehat{H[N]} \rangle$. In particular, some key innovations in our algorithm substantially reduce the computational complexity in the Lorentzian part of $\langle\widehat{H[N]}\rangle$. Moreover, the algorithm developed in the present work makes it possible to compute the expectation value of arbitrary monomial of holonomies and fluxes on one edge up to arbitrary order of $\ell_{\rm p}^2$.
分类: 生物学 >> 生物化学 提交时间: 2020-02-12
摘要: 最近,在中国武汉爆发了肺炎病例,由一种名为2019-CoV的新型冠状病毒引起。我们之前的研究中,根据中国深圳的12例2019-nCoV感染患者的临床特征,所有病例均患有肺炎,一半病例发展为急性呼吸窘迫综合征(ARDS)。本文中,我们针对这12例患者的血浆因子表达谱进行了研究。我们测试了2019-nCoV感染患者血浆中的48个因子的表达,其中38个因子与健康个体相比显着升高;2019-nCoV感染的重症患者血浆中的高细胞因子血症水平显著低于A型流感病毒H7N9感染患者,而略高于细菌感染患者。在这38个细胞因子中,有17个与2019-CoV病毒载量相关,其中的15个(M-CSF,IL-10,IFN-α2,IL-17,IL-4,IP-10,IL-7,IL-1受体拮抗剂,G-CSF,IL-12 (p40),IFN-γ,IL-1α,IL-2,HGF和PDGF-BB)与肺损伤Murray评分高度相关,可用来预测2019-nCoV感染患者的疾病严重程度。我们的研究结果表明,这15种高细胞因子可能是衡量2019-nCoV感染患者疾病严重程度的潜在生物标志物,影响这些信号传递介质的因子可能是针对新型2019-nCoV大流行的潜在药物。
分类: 生物学 >> 生物化学 提交时间: 2020-02-08
摘要: 新型冠状病毒(2019-nCoV)自2019年12月在湖北省武汉市爆发,并迅速传播到中国多地及其他国家。在本研究中,我们报告了来自中国深圳早期的2019-nCoV感染患者的流行病学、临床指标、生化指标和影像学特征,以及可用于预测疾病严重程度的潜在生物标记物。所有12例2019-nCoV感染的肺炎患者均发展为肺炎,其中一半患者进一步发展为急性呼吸窘迫综合征(acute respiratory distress syndrome,ARDS)。最常见的实验室检测生化指标异常是低白蛋白(albumine,ALB)血症、淋巴细胞(lymphocytes,LYM)计数减少,淋巴细胞百分比和中性粒细胞(neutrophils,NEU)百分比降低,C反应蛋白(C-reactive protein,CRP)和乳酸脱氢酶(lactate dehydrogenase,LDH)水平升高,以及CD8细胞计数降低。从患者呼吸道特别是下呼吸道检测到的2019-nCoV病毒滴度与肺部疾病的严重程度正相关。 ALB、LYM、LYM(%)、LDH、NEU(%)和CRP的水平与急性肺损伤程度高度相关。年龄、病毒滴度、肺损伤评分和血液生化指标:ALB、CRP、LDH、LYM(%)、LYM和NEU(%)可能是疾病严重程度的预测指标。此外, 2019-nCoV感染患者的血浆血管紧张素II水平显着升高,并且与病毒滴度和肺损伤程度线性相关。我们的研究结果提供了多种潜在的可用于诊断的生物标志物, 并提出了血管紧张素 II受体阻滞剂(angiotensin II receptor blocker,ARB)药物或可作为治疗2019-nCoV感染的潜在药物进行深入研究。