Equilibrium points and periodic orbits in irregular gravitational fields are significant for an understanding of dynamical behaviors around asteroids as well as deep space exploring missions. The dipole segment is a g...Equilibrium points and periodic orbits in irregular gravitational fields are significant for an understanding of dynamical behaviors around asteroids as well as deep space exploring missions. The dipole segment is a good alternative model to study qualitative dynamical properties near dumbbell-shaped asteroids. In this paper, the dipole segment model and its equilibrium points are simply introduced. The stability of the two triangular equilibrium points of the system is numerically examined. Next, periodic orbits are presented around the dipole segment model in two different cases, in which triangular equilibria are linearly stable and unstable,respectively. New types of periodic orbits are illustrated in detail, including their orbital shapes, periods and the Jacobi integral.The orbital stability, topological classification and bifurcations of these orbits are also analyzed with numerical continuations.展开更多
AIM: To study sleep aspects and parameters in cirrhotic patients and assess the role of liver dysfunction severity in polysomnographic results. METHODS: This was a case-control study. Patients with a diagnosis of live...AIM: To study sleep aspects and parameters in cirrhotic patients and assess the role of liver dysfunction severity in polysomnographic results. METHODS: This was a case-control study. Patients with a diagnosis of liver cirrhosis were consecutively enrolled in the study. Clinical examinations and laboratory liver tests were performed in all patients, and disease severity was assessed using the Child-Pugh score. The control group consisted of ageand gender-matched healthy volunteers. All individuals answered a questionnaire about habits, behaviors, and complaints related to sleep and were submitted to polysomnography. Sleep parameters were compared between the two groups, and separate analyses were performed among classesof Child-Pugh classification in the cirrhotic group. RESULTS: Forty-two cirrhotic patients and forty-two controls were enrolled. Compared to the control group, the cirrhotic group exhibited lower sleep efficiency (mean ± SD: 73.89% ± 14.99% vs 84.43% ± 8.55%, P < 0.01), increased latency (151.27 ± 93.24 min vs 90.62 ± 54.74 min, P < 0.01) and a lower percentage of rapid eye movement (REM) sleep (14.04% ± 5.64% vs 20.71% ± 6.77%, P < 0.05) as well as a higher frequency of periodic limb movements (10.56 ± 2.85/h vs 2.79 ± 0.61/h, P < 0.01). The comparison of sleep parameters among Child A, B and C cirrhotic patients revealed a significant reduction of REM sleep stage occurrence in individuals with severe liver disease (Child C patients) compared to Child A/B patients (polysomnography percentage of REM sleep stage of patients Child A: 16.1% ± 1.2%; Child B: 14.9% ± 1.2%; Child C: 8.6% ± 1.6%, P < 0.05). CONCLUSION: Cirrhosis was associated with shorter sleep time, reduced sleep efficiency, increased sleep latency, increased REM latency and reduced REM sleep. Additionally, disease severity influences sleep parameters.展开更多
For d particular Riccati equation on torns T2,an exact relation (28) between the generators of its monodromy group and theparameter A E R is obtained, so that the dependence of the properties of themonodromy group on ...For d particular Riccati equation on torns T2,an exact relation (28) between the generators of its monodromy group and theparameter A E R is obtained, so that the dependence of the properties of themonodromy group on the parameter A can be discussed globally. It is provedthat the limit set of the monodromy group has a fractal structure if and only if展开更多
In this artical the existence, stability and asymptoticity of periodic solutionfor Abel equation :as well as ones for its special cases are discussed, where a(t), b(t), c(t) and d(t)are real periodic functions.
In this paper, the existence and uniqueness of periodic solutions of linearfunctional differential equat,ions, including neutral equations, with constant coef-ficients are investigated, necessary and sufficient condit...In this paper, the existence and uniqueness of periodic solutions of linearfunctional differential equat,ions, including neutral equations, with constant coef-ficients are investigated, necessary and sufficient conditions for the existence anduniqueness of periodic solutions of linear neutral functional differential equationsand some of their special oases are given via systems of linear algebraic equations. Especially, the problems of existonce and Uniqueness of periodic solutions ofgeneral linear functional differential equations of non-neutral type are completelysolved.展开更多
古土壤形成于过去环境,是揭示环境变化历史的重要材料。新近纪(23.03 M a)以前形成的古土壤,年代久远、埋藏深、受成岩作用改造强烈,其发生学特征研究是古环境重建的基础。本文通过对白垩纪时期不同地点的钙质古土壤的发生学研究,拟恢...古土壤形成于过去环境,是揭示环境变化历史的重要材料。新近纪(23.03 M a)以前形成的古土壤,年代久远、埋藏深、受成岩作用改造强烈,其发生学特征研究是古环境重建的基础。本文通过对白垩纪时期不同地点的钙质古土壤的发生学研究,拟恢复研究区域古环境。研究表明,古土壤剖面中的A层和B层形态分别产生变化,但层次差异依然明显,且表层土壤有机质含量一般高于表下层,钙积层(Bk)普遍发生并富含碳酸盐结核。可以观察到古土壤中方解石沿根孔淀积特征以及具滑擦面。钙质古土壤质地偏粗,为壤质砂土和砂质壤土。古土壤Bk层中的Ca、Mn、Sr相对富集,其余常量元素与Ba、Sc、Nb、Th、U、Cr、V、Co、N i等元素降低;δCe和δEu负异常以及相对富集重稀土元素。分别按照中国土壤分类系统和美国土壤系统分类两种分类体系进行了古土壤分类。由古土壤类型和特征可以推断白垩纪不同时期,在四川盆地梓潼—巴中地区、辽宁金岭寺—羊山盆地和松辽盆地出现过半湿润至半干旱的气候环境。展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.11602019&11572035)the Young Elite Scientist Sponsorship Program by China Association for Science and Technology(Grant No.2016QNRC001)Excellent Young Teachers Program of Beijing Institute of Technology(Grant No.2015YG0605)
文摘Equilibrium points and periodic orbits in irregular gravitational fields are significant for an understanding of dynamical behaviors around asteroids as well as deep space exploring missions. The dipole segment is a good alternative model to study qualitative dynamical properties near dumbbell-shaped asteroids. In this paper, the dipole segment model and its equilibrium points are simply introduced. The stability of the two triangular equilibrium points of the system is numerically examined. Next, periodic orbits are presented around the dipole segment model in two different cases, in which triangular equilibria are linearly stable and unstable,respectively. New types of periodic orbits are illustrated in detail, including their orbital shapes, periods and the Jacobi integral.The orbital stability, topological classification and bifurcations of these orbits are also analyzed with numerical continuations.
基金Supported by Grants from the Associao Fundo de Incentivo a Pesquisa and FAPESP-CEPID-Proc. 95/14303-3
文摘AIM: To study sleep aspects and parameters in cirrhotic patients and assess the role of liver dysfunction severity in polysomnographic results. METHODS: This was a case-control study. Patients with a diagnosis of liver cirrhosis were consecutively enrolled in the study. Clinical examinations and laboratory liver tests were performed in all patients, and disease severity was assessed using the Child-Pugh score. The control group consisted of ageand gender-matched healthy volunteers. All individuals answered a questionnaire about habits, behaviors, and complaints related to sleep and were submitted to polysomnography. Sleep parameters were compared between the two groups, and separate analyses were performed among classesof Child-Pugh classification in the cirrhotic group. RESULTS: Forty-two cirrhotic patients and forty-two controls were enrolled. Compared to the control group, the cirrhotic group exhibited lower sleep efficiency (mean ± SD: 73.89% ± 14.99% vs 84.43% ± 8.55%, P < 0.01), increased latency (151.27 ± 93.24 min vs 90.62 ± 54.74 min, P < 0.01) and a lower percentage of rapid eye movement (REM) sleep (14.04% ± 5.64% vs 20.71% ± 6.77%, P < 0.05) as well as a higher frequency of periodic limb movements (10.56 ± 2.85/h vs 2.79 ± 0.61/h, P < 0.01). The comparison of sleep parameters among Child A, B and C cirrhotic patients revealed a significant reduction of REM sleep stage occurrence in individuals with severe liver disease (Child C patients) compared to Child A/B patients (polysomnography percentage of REM sleep stage of patients Child A: 16.1% ± 1.2%; Child B: 14.9% ± 1.2%; Child C: 8.6% ± 1.6%, P < 0.05). CONCLUSION: Cirrhosis was associated with shorter sleep time, reduced sleep efficiency, increased sleep latency, increased REM latency and reduced REM sleep. Additionally, disease severity influences sleep parameters.
文摘For d particular Riccati equation on torns T2,an exact relation (28) between the generators of its monodromy group and theparameter A E R is obtained, so that the dependence of the properties of themonodromy group on the parameter A can be discussed globally. It is provedthat the limit set of the monodromy group has a fractal structure if and only if
文摘In this artical the existence, stability and asymptoticity of periodic solutionfor Abel equation :as well as ones for its special cases are discussed, where a(t), b(t), c(t) and d(t)are real periodic functions.
文摘In this paper, the existence and uniqueness of periodic solutions of linearfunctional differential equat,ions, including neutral equations, with constant coef-ficients are investigated, necessary and sufficient conditions for the existence anduniqueness of periodic solutions of linear neutral functional differential equationsand some of their special oases are given via systems of linear algebraic equations. Especially, the problems of existonce and Uniqueness of periodic solutions ofgeneral linear functional differential equations of non-neutral type are completelysolved.
文摘古土壤形成于过去环境,是揭示环境变化历史的重要材料。新近纪(23.03 M a)以前形成的古土壤,年代久远、埋藏深、受成岩作用改造强烈,其发生学特征研究是古环境重建的基础。本文通过对白垩纪时期不同地点的钙质古土壤的发生学研究,拟恢复研究区域古环境。研究表明,古土壤剖面中的A层和B层形态分别产生变化,但层次差异依然明显,且表层土壤有机质含量一般高于表下层,钙积层(Bk)普遍发生并富含碳酸盐结核。可以观察到古土壤中方解石沿根孔淀积特征以及具滑擦面。钙质古土壤质地偏粗,为壤质砂土和砂质壤土。古土壤Bk层中的Ca、Mn、Sr相对富集,其余常量元素与Ba、Sc、Nb、Th、U、Cr、V、Co、N i等元素降低;δCe和δEu负异常以及相对富集重稀土元素。分别按照中国土壤分类系统和美国土壤系统分类两种分类体系进行了古土壤分类。由古土壤类型和特征可以推断白垩纪不同时期,在四川盆地梓潼—巴中地区、辽宁金岭寺—羊山盆地和松辽盆地出现过半湿润至半干旱的气候环境。
