880 nm LD pumped passive mode-locked TEM00 Nd:YVO4 laser based on SESAM

We report on an 880 nm LD pumped passive mode-locked TEM00 Nd:YVO4 laser based on a semiconductor saturable absorber mirror (SESAM) for the first time. When the incident pump power was 16 W, 4.76 W average output power of continuous-wave mode-locked laser with an optical-to-optical conversion efficiency of 30% was achieved. The repetition rate of mode-locked pulse was 80 MHz with 25 ps pulse width. The maximum pulse energy and peak power were 60 nJ and 2.4 kW, respectively.

LD Side-Pumped Passive Mode-Locked TEM00 Nd:YAG Laser Based on SESAM

We report an LD side-pumped continuous-wave passive mode-locked Nd:YAG laser with a Z-type folded cavity based on a semiconductor saturable absorber mirror (SESAM). The average output power 2.95 W of mode-locked laser with electro-optical conversion efficiency of 1.3% and high beam quality (M-x(2) = 1.25 and M-y(2) = 1.22) is achieved. The repetition rate of mode-locked pulse of 88 MHz with pulse energy of 34 nJ is obtained.

Strain effects on optical polarisation properties in (11(2)over-bar2) plane GaN films

We present the theoretical results of the electronic band structure of wurtzite GaN films under biaxial strains in the (11 (2) over bar2)-plane The calculations are performed by the kappa p perturbation theory approach through using the effective-mass Hamiltonian for an arbitrary direction The results show that the transition energies decrease with the biaxial strains changing from -0 5% to 0 5% For films of (11 (2) over bar2)-plane, the strains are expected to be anisotropic in the growth plane Such anisotropic strains give rise to valence band mixing which results in dramatic change in optical polarisation property The strain can also result in optical polarisation switching phenomena Finally, we discuss the applications of these properties to the (11 (2) over bar2) plane GaN based light emitting diode and lase diode

Effects of oriented substrates on cell morphology, the cell cycle, and the cytoskeleton in Ros 17/2.8 cells

Absence of gravity or microgravity influences the cellular functions of bone forming osteoblasts. The underlying mechanism, however, of cellular sensing and responding to the gravity vector is poorly understood. This work quantified the impact of vector-directional gravity on the biological responses of Ros 17/2.8 cells grown on upward-, downward- or edge-on-oriented substrates. Cell morphology and nuclear translocation, cell proliferation and the cell cycle, and cytoskeletal reorganization were found to vary significantly in the three orientations. All of the responses were duration-dependent. These results provide a new insight into understanding how osteoblasts respond to static vector-directional gravity.

X射线诱导的HeLa细胞旁效应中ROS和NO关系研究

活性氧(ROS)和一氧化氮(NO)是辐射诱导的旁效应信号通路中的两个重要信号分子。实验研究了这两种信号分子在HeLa细胞旁效应信号通路中的关系。通过微核实验,发现X射线辐照过的HeLa细胞及其旁观者细胞微核形成明显增加,而二甲亚砜(DMSO)预处理显著抑制了微核形成。另外还发现,接受条件培养基的旁观者细胞的增殖速率增加,而DMSO预处理产生条件培养基的受辐照细胞则使旁观者细胞的增殖速率降低。以上的结果从不同角度证实了HeLa细胞存在X射线诱导的旁效应,且其可以被DMSO预处理所抑制。Western blotting和DAF-FMDA荧光探针检测分别显示出辐照后细胞的诱导型一氧化氮合酶(iNOS)和NO水平均升高,而DMSO预处理则降低其水平。因此,可以推测X射线诱导的HeLa旁效应当中ROS是NO的上游信号。

超对称电磁相互作用系统的BRST量子化及其正则Ward恒等式

运用Becchi-Rouet-Stora-Tyutin路径积分量子化方法对超对称电磁相互作用系统进行了量子化.在相空间中化简了超对称电磁相互作用系统Hamiltonian量,进而使该系统的量子化被化简.构造体系的BRST生成元,得到了系统的BRST变换;给出了有效作用量,得到了Green函数生成泛函;构造了体系的规范生产元,并得到了系统的规范对称变换.最后,基于正则系统的Noether定理,给出了规范变换的Ward-Takahashi恒等式,进而讨论了正规顶角和传播子的关系,给出了正规顶角和传播子的两个关系式.

周期轨道与求迹公式-可积系统

选择二维无关联四次振子系统作为理论模型来验证Berry-Tabor公式的有效性 .在有理环面上积分Hamiltonian运动方程得到一系列的周期轨道 ,细致构造有理环面附近的轨道得到能量面上的曲率 ,并应用Berry -Tabor求迹公式经过Fourier变换得到的作用量函数 ,在作用量S <3 0的区间上 ,与得到的相应量子作用量函数进行了比较 ,其结果的一致性验证了求迹公式的有效性 .最后 ,对量子作用量函数RQM(S ,E) -S图上经典周期轨道作用量处出现的δ峰进行了讨论

可积系统——求迹公式和逆谱分析(英文)

研究了二维无关联四次振子系统 ,有理环面上积分 Hamiltonian运动方程给出了系统一系列周期轨道和经典物理量 ,使用半经典近似下的 Berry- Tabor求迹公式 ,得到了半经典的态密度 .应用 Fourier变换分析了每条周期轨道对态密度的贡献 ,并与量子态密度的 Fourier变换结果比较证实了半经典求迹公式的有效性

Low-lying states of heavy nuclei within the nucleon pair approximation

In this article we perform systematic calculations on low-lying states of 33 nuclei with A=202-212, using the nucleon pair approximation of the shell model. We use a phenomenological shell-model Hamiltonian that includes single-particle energies, monopole and quadrupole pairing interactions, and quadrupole-quadrupole interactions. The building blocks of our model space include one J=4 valence neutron pair, and one J=4,6,8 valence proton pair, in addition to the usual S and D pairs. We calculate binding energies, excitation energies, electric quadrupole and magnetic dipole moments of low-lying states, and E2 transition rates between low-lying states. Our calculated results are reasonably consistent with available experimental data. The calculated quadrupole moments and magnetic moments, many of which have not yet been measured for these nuclei, are useful for future experimental measurements.

BRST quantization and canonical Ward identity of the supersymmetric electromagnetic interaction system

According to the method of path integral quantization for the canonical constrained system in Becchi-Rouet-Stora-Tyutin scheme, the supersymmetric electromagnetic interaction system was quantized. Both the Hamiltonian of the supersymmetric electromagnetic interaction system in phase space and the quantization procedure were simplified. The BRST generator was constructed, and the BRST transformations of supersymmetric fields were gotten; the effective action was calculated, and the generating functional for the Green function was achieved; also, the gauge generator was constructed, and the gauge transformation of the system was obtained. Finally, the Ward-Takahashi identities based on the canonical Noether theorem were calculated, and two relations between proper vertices and propagators were obtained.

A novel approach to isoscaling: The role of the order parameter m = N-f-Z(f)/A(f)

Isoscaling is derived within a recently proposed modified Fisher model where the free energy near the critical point is described by the Landau O(m(6)) theory. In this model m = N-f-Z(f)/A(f) is the order parameter, a consequence of (one of) the symmetries of the nuclear Hamiltonian. Within this framework we show that isoscaling depends mainly on this order parameter through the 'external (conjugate) field' H. The external field is just given by the difference in chemical potentials of the neutrons and protons of the two sources. To distinguish from previously employed isoscaling relationships, this approach is dubbed: m-scaling. We discuss the relationship between this framework and the standard isoscaling formalism and point out some substantial differences in interpretation of experimental results which might result. These should be investigated further both theoretically and experimentally. (C) 2010 Elsevier B.V. All rights reserved.

二维无关联振子系统的量子化及能谱中长程关联的理论分析

量子经典对应是人们一直关心的基本问题．早期的WKB量子论及其推广EBK理论分别给出了一维及多维可积系统周期轨道的作用量量子化条件，但是，这些理论都没有明确的给出周期轨道与量子能级之间的对应关系．另一方面，近年来，人们在数值计算中发现量子能谱中存在着与周期轨道有紧密联系的长程关联，但是目前对长程关联的研究大多局限于数值计算，其背后的动力学原因有待进一步的探讨。应用二维无关联振子系统具有的标度不变性，对量子态密度进行Fourier变换，得到二维无关联振子系统的回归函数．另一方面，在有理环面上积分Hamiltonian运动方程，数值计算给出二维无关联四次振子系统的半经典回归谱。对二维无关联四次振子系统的量子回归谱和经典回归谱进行比较，量子和经典回归谱中的峰(显示了能级之间存在着长程关联)的位置大致一定验证了Berry-Tabor求迹公式的有效性。从可积系统的Be：rry-Tabor公式出发，导出了二维可积系统周期轨道作用量量子化条件，考虑有理环面上周期轨道必须满足的周期性条件，找到了量子能级与经典周期轨道之间的对应关系．这一对应关系表明，二维无关联振子系统的一组能级与一组周期轨道之间存在着一一对应关系。这组能级对应的周期轨道具有相同的拓扑，但每条周期轨道对应的系统能量等于它所对应的量子能级。进一步的，我们用二维无关联振子系统的量子经典对应关系去分析量子能谱中的长程关联。分析表明，当二维无关联振子系统回归函数中的作用量取某一系统能量下某一周期轨道的作用量的值时，那些与这一周期轨道拓扑相同的周期轨道对应的量子能级对回归函数的贡献相干。这些具有相同拓扑的周期轨道对应的量子能级间存在着长程关联。

应用IBM-2对混合对称态的一些探讨

本文应用相互作用玻色子模型（IBM-2）的理论对混合对称态作了一些讨论。首先给出IBM-2普遍的和一种简化的Hamiltonian的Casimir算子展开式，通过对几种简化Hamiltonian动力学对称性和F-旋对称性的分析，并且考虑最主要的核子相互作用，选择了一种较理想的简化Hamiltonian。其次，用最小二乘法提取了部分U（5）类核和O（6）类核的玻色子等效电荷，并用此计算了它们的混合对称态的电磁跃迁几率。最后，用数值方法系统地计算和分析了~(150,152,154)Gd核混合对称态的能级和电磁跃迁几率，得到~(150)G和~(152,154)Gd核最低能量的混合对称态分别为2_M~+和I_M~+。另外，还详细讨论了Majorana相互作用参数对能级和电磁跃迁几率的影响