MRI analysis of right ventricular function in normal and spontaneously hypertensive rats

Right ventricular structure and function were characterized in spontaneously hypertensive rats (SHR) using non-invasive magnetic resonance imaging (MRI) techniques. These studies therefore complement previous reports preoccupied with left ventricular changes associated with this condition. Eight SHR and eight control normotensive Wistar-Kyoto (WKY) rats were each subdivided into equal age-matched groups of 8 and 12 weeks. The right ventricle was imaged through a series of twelve contiguous 1.37–1.75 mm transverse sections at twelve equally spaced time-points that covered both systole and most of diastole thereby completely reconstructing right ventricular anatomy. This gave measurements of right ventricular myocardial mass that were consistent through all twelve time-points in all four experimental groups throughout their cardiac cycles. However, spontaneous hypertension increased this right ventricular myocardial mass, as well as the end-diastolic (EDV) and end-systolic volumes (ESV). Although stroke volume (SV) was conserved, decreases in ejection fraction (EF), a positive shift in the relationship between SV and EDV, and reduced indices of systolic ejection rates in SHR rats compared with the age-matched normal WKY controls indicated significant systolic dysfunction. Additionally, reductions in the rates of diastolic relaxation suggested the onset of diastolic dysfunction. Thus, the non-invasive nature of MRI has made it possible for the first time to demonstrate alterations in structure of the right ventricle and in quantitative indicators of its systolic and diastolic function in the SHR model of hypertension.     

Asymptotically Local Minimax Estimation of Infinitely Smooth Density with Censored Data

The problem of the nonparametric minimax estimation of an infinitely smooth density at a given point, under random censorship, is considered. We establish the exact asymptotics of the local minimax risk and propose the efficient kernel-type estimator based on the well known Kaplan-Meier estimator.     

时空奇点和黑洞——2020年诺贝尔物理学奖解读

2020年度诺贝尔物理学奖于北京时间2020年10月6日晚揭晓,其中一半奖金授予罗杰·彭罗斯(Roger Penrose),表彰他"发现黑洞的形成是广义相对论的必然预言";另一半奖金授予莱因哈德·根泽尔(Reinhard Genzel)和安德里亚·格兹(Andrea Ghez),因为他们"在银河系中心发现了一个超大质量...     

随机删失下位置-刻度模型中的强相合与渐近正态估计

在删失分布未知的情形下,证明了所定义的位置─刻度模型中参数估计的强相合性与渐近正态性．在证明估计的渐近正态性时,使用了点过程鞅方法．     

The almost sure behavior of the oscillation modulus for PL-process and cumulative hazard process under random censorship

The local behavior of oscillation modulus of the product-limit (PL) process and the cumulative hazard process is investigated when the data are subjected to random censoring. Laws of the iterated logarithm of local oscillation modulus for the PL-process and the cumulative hazard process are established. Some of these results are applied to obtain the almost sure best rates of convergence for various types of density estimators as well as the Bahadur-Kiefer type process. Project supported in part by the National Natural Science Foundation of China (Grant No. 19701037).     

正三角型结构三光纤出射光场干涉理论模型及其实验

利用三根光纤以正三角形的方式组合在一起,实现了三光纤Moiré干涉,建立了纤端出射场干涉模型,并进行了理论计算.实验结果与理论计算结果符合较好.为光纤莫尔传感技术的应用和发展提供了理论和实验依据.     

Weak cosmic censorship conjecture and thermodynamics in quintessence AdS black hole under charged particle absorption

Considering the cosmological constant as the pressure, this study addresses the laws of thermodynamics and weak cosmic censorship conjecture in the Reissner-Nordstr?m-AdS black hole surrounded by quintessence dark energy under charged particle absorption. The first law of thermodynamics is found to be valid as a particle is absorbed by the black hole. The second law, however, is violated for the extremal and near-extremal black holes, because the entropy of these black hole decrease. Moreover, we find that the extremal black hole does not change its configuration in the extended phase space, implying that the weak cosmic censorship conjecture is valid. Remarkably, the near-extremal black hole can be overcharged beyond the extremal condition under charged particle absorption. Hence, the cosmic censorship conjecture could be violated for the near-extremal black hole in the extended phase space. For comparison, we also discuss the first law, second law, and the weak cosmic censorship conjecture in normal phase space, and find that all of them are valid in this case.     

Revisiting black hole thermodynamics in massive gravity: charged particle absorption and infalling shell of dust

In this study, we apply two methods to consider the variation of massive black holes in both normal and extended thermodynamic phase spaces. The first method considers a charged particle being absorbed by the black hole, whereas the second considers a shell of dust falling into it. With the former method, the first and second laws of thermodynamics are always satisfied in the normal phase space; however, in the extended phase space, the first law is satisfied but the validity of the second law?of?thermodynamics depends upon the model parameters. With the latter method, both laws are valid. We argue that the former method's violation of the second law of thermodynamics may be attributable to the assumption that the change of internal energy of the black hole is equal to the energy of the particle. Finally, we demonstrate that the event horizon always ensures the validity of weak cosmic censorship in both phase spaces; this means that the violation of the second law of thermodynamics, arising under the aforementioned assumption, does not affect the weak cosmic censorship conjecture. This further supports our argument that the assumption in the first method is responsible for the violation and requires deeper treatment.     

Thermodynamics and weak cosmic censorship conjecture of 4D Gauss-Bonnet-Maxwell black holes via charged particle absorption

Recently, the non-trivial solutions for 4-dimensional black holes of Einstein-Gauss-Bonnet gravity had been discovered. In this paper, considering a charged particle entering into a 4-dimensional Gauss-Bonnet-Maxwell black hole, we calculate the black hole thermodynamic properties using the Hamilton-Jacobi equation. In the normal phase space, the cosmological constant and Gauss-Bonnet parameter are fixed, the black hole satisfies the first and second laws of thermodynamics, and the weak cosmic censorship conjecture (WCCC) is valid. On the other hand, in the case of extended phase space, the cosmological constant and Gauss-Bonnet parameter are treated as thermodynamic variables. The black hole also satisfies the first law of thermodynamics. However, the increase or decrease in the black hole's entropy depends on some specific conditions. Finally, we observe that the WCCC is violated for the near-extremal black holes in the extended phase space.     

Thermodynamics and weak cosmic censorship conjecture of an AdS black hole with a monopole in the extended phase space

The first law of black hole thermodynamics has been shown to be valid in the extended phase space.However,the second law and the weak cosmic censorship conjecture have not been investigated extensively.We investigate the laws of thermodynamics and the weak cosmic censorship conjecture of an AdS black hole with a global monopole in the extended phase space in the case of charged particle absorption.It is shown that the first law of thermodynamics is valid,while the second law is violated for the extremal and near-extremal black holes.Moreover,we find that the weak cosmic censorship conjecture is valid only for the extremal black hole,and that it can be violated for the near-extremal black holes,which is different from the previous results.