Volume transfer constant (K) maps from dynamic contrast enhanced MRI as potential guidance for MR-guided high intensity focused ultrasound treatment of hypervascular uterine fibroids

Higher perfusion of uterine fibroids at baseline is recognized as cause for poor efficacy of MR-guided high intensity focused ultrasound (HIFU) ablation, and higher acoustic power has been suggested for the treatment of high-perfused areas inside uterine fibroids. However, considering the heterogeneously vascular distribution inside the uterine fibroids especially with hyper vascularity, it is not easy to choose the correct therapy acoustic power for every part inside fibroids. In our study, we presented two cases of fibroids with hyper vascularity, to show the differences between them with different outcomes. Selecting higher therapy acoustic powers to ablate high-perfused areas efficiently inside fibroids might help achieving good ablation results. Volume transfer constant (K^trans) maps from dynamic contrast-enhanced (DCE) imaging at baseline helps visualizing perfusion state inside the fibroids and locating areas with higher-perfusion. In addition, with the help of K^trans maps, appropriate therapy acoustic power could be selected by the result of initial test and therapy sonications at different areas with significantly different perfusion state inside fibroids.     

啁啾光脉冲在类时间透镜介质中的传播

利用空间－时间类似和光线光学方法得到啁啾高斯光脉冲在类时间透镜介质中传播的解析解，讨论了光脉冲宽度和啁啾参数随传播距离的演变，并与光脉冲在克尔介质中传播的特征作了比较。     

Time-Domain Mapping of Electromagnetic Ray Movement Inside 2D Anisotropic Region

The paper presents the extension of the time-domain mapping method applied to 2D billiard problem inside an anisotropic region bounded by ellipse [1]. In this paper, it has been considered the ray movement inside 2D anisotropic region bounded by arbitrary differentiable curve. It has been proved that the problem can be one-to-one mapped onto 2D mathemeatical billiard problem inside the region possessing isotropic properties by linear transformation of group velocity hodograph and boundary with the same coefficient, which is equal to anisotropy of the ray group velocity, simultaneously. The main features of the ray movement inside 2D anistropic region are discussed.     

曲率对Rh在锯齿型单壁碳纳米管内外吸附影响的研究

利用密度泛函理论系统的研究了单壁碳纳米管的曲率对Rh原子在锯齿型碳管内外的吸附行为, 发现Rh原子在管外吸附比管内稳定; 随着碳管管径的增加, 曲率减小, 管内外吸附能的差值逐渐减小, 接近Rh原子在石墨烯上的吸附能. 电荷密度分析表明, 由于卷曲效应使碳纳米管管外的电荷密度大于管内, 随着曲率减小, 这种差别逐渐减小. 管内外吸附Rh原子的Bader电荷差值及局域态密度差别亦随着曲率的下降而减小, 这与Rh原子在管内外吸附能的变化规律相一致.     

二次曲面线圈中的均匀磁场

基于对旋转椭球内部磁场的讨论,采用Matlab数值计算的方法计算了旋转椭球的内部磁场.对于旋转抛物球和双曲球面,用相同方法绕制线圈也能得到均匀的磁场.印证了内部磁场计算的公式,并提出了一种产生大范围均匀磁场的方法.     

原子的选择测量对原子纠缠特性和场熵的影响*

考虑初始处于W态的三个二能级原子,将其中两个原子同时注入处于真空态的单模腔中,并与光场发生共振相互作用的情况。采用数值计算方法,通过对是否进行原子态选择性测量情况下,腔内原子间的纠缠性质和场熵的比较,讨论了对腔外原子的态选择性测量对腔内原子间的纠缠性质和场熵演化的影响。研究结果表明：对腔外原子的选择性测量,可增强腔内原子间的纠缠,但会减弱腔內原子与光场的关联。     

Laser beam transmission and focusing inside media

A mathematical model for analyzing laser beam transmission and focusing inside media is developed. The reflection and refraction on the interface between two different media and the absorption inside media are considered. Based on the mathematical model a computer program, which allows us to analyze the focusing and transmission processes of laser beam as well as to obtain the beam parameters and intensity profile inside media, is created.     

Optical Ray Movement Inside Dielectric Sphere

The paper presents results of numerical investigations of electromagnetic (optical) ray propagation inside a sphere, made of optically uniaxial crystal. The types of caustics formed by the ray trajectory inside the sphere are cleared up. It has been demonstrated the difference between types of caustics formed by the extraordinary ray trajectory inside the sphere made of optically positive and negative crystals. Results are discussed on the basis of one-to-one mapping of 2D billiard problem inside isotropic region bounded by ellipse onto anisotropic one.     

Topological changes in bipolar nematic droplets under flow

Bipolar liquid crystal drops moving inside microchannels exhibit periodic director field transformations due to induced circulating flows inside them. These modifications are characterized by changes in the type of point surface disclinations; they periodically change from splay to bend disclinations, implying the drop changes between bipolar and escaped concentric configurations. Upon stopping the flow, this structure does not relax to the lower energy bipolar configuration; we argue this is due to drop flattening inside the channels.     

Surface characterization of plasma-modified resist patterns by ToF-SIMS analysis

We report the use of the time-of-flight secondary ion mass spectrometry (ToF-SIMS) technique to determine whether the patterned bank is suitable for inkjet printing, by evaluating the phobicity contrast between two regions, the glass substrate inside pixels and the surface of the resist bank. We first examined the effect of plasma treatment on the ink spreading behavior inside pixels. The phobicity contrast was optimized by removing residues inside the pixels and by providing high phobicity on the bank surface. We show that ToF-SIMS spectra and mass-resolved images are effective tools in examining the existence of organic contaminants inside pixels and predicting the actual inkjet printing behavior. The ToF-SIMS technique will find promising applications that are related to surface characteristics where conventional contact angle measurement is hard to apply due to geometrical and technical restrictions.     

Moisture gradient vector calculation as a new method for evaluating NMR images of corn (Zea Mays L.) kernels during drying.

Magnetic resonance imaging (MRI) was used to study the moisture migration inside single corn kernel during artificial drying. MRI data were taken every half an hour during drying while the intact kernel was kept inside the magnet. The moisture distribution was not uniform inside the kernel during drying, with the fastest moisture loss being detected in the endosperm, whilst the scutellum maintained the water. Resultant gradient vectors were visualized, as a new evaluation method, from each pixel of the subtraction of segmented MRI images showing the movement of proton density inside the kernel. The data matrix containing the gradient vectors can be stored for latter use as input parameters and to check the mass transfer models.     

内源全息术的原理和数学描述

以往的全息术在对原子成像时,在相干光源、探测器空间分辨和信号强度三个方面遇到了难以克服的困难. 阐述了内源全息术克服这些困难的原理,研究了内源全息术的记录和再现全过程,推导出内源球面全息图的再现公式,并在散射因子球对称近似和能量无关近似下,推导出以δ函数表示原子全息再现像的解析表达式. 关键词： 内源全息术 同步辐射 晶体结构 傅里叶变换     

Resonant holography

We present a method of enhancing the diffraction efficiency of a hologram by placing it inside a resonant optical cavity. The diffraction efficiency improves on account of the multiple passes that the incident light undergoes inside the optical cavity. The resonance condition in this case turns out to involve both mirror reflectivity and the optical path length inside the cavity. Experimental results for a resonantly enhanced angle-multiplexed holographic memory and an optical three-port element are shown.     

微小圆通道内流动沸腾换热特性的研究

微小通道内相变换热具有热流密度高、单位体积内换热面积大、结构紧凑等特点,成为高效紧凑式换热器设计的重要途径。本文以氟利昂R113为工质,完成了0.7、1.1和1.4 mm的圆形小通道内的流动沸腾实验,对小通道内流动沸腾换热特性进行了分析,拟合了计算沸腾换热特性的实验关联式,为工程实际应用提供参考。     

Observation of reduced heat transport inside the magnetic island O point in the large helical device

Evidence for a reduction of heat transport inside the magnetic island O point is observed from the propagation of a cold pulse produced by a tracer encapsulated solid pellet in the Large Helical Device. A small peak and slow propagation of the cold pulse are observed inside the island. A significant result is that electron heat diffusivity inside the island is estimated to be 0.2 m(2)/s which is smaller than that outside the island by an order of magnitude.     

Bound states of Dirac electrons in a graphene-based magnetic quantum dot

We investigate the magnetically confined states of the massless Dirac fermions in a graphene quantum dot formed by the inhomogeneous distributions of the magnetic fields inside and outside the dot. The calculated energy spectrum exhibits quite different features with and without the magnetic field inside the dot. It is found that the degeneracy of the relativistic Landau level with negative angular momenta can be lifted, and this degeneracy breaking can be modulated by the magnetic field inside the dot. Moreover, such a system can form the strongly localized states within the dot and along its boundary, especially with the magnetic field inside the dot.     

Focusing of X-Rays inside a single crystal under the temperature gradient

A method for experimental investigation of the effect of X-ray focusing inside a single crystal subject to temperature gradient is proposed. The definition of diffracted X-ray focusing inside the crystal is shown to increase depending on the value of temperature gradient.     

Radiation heat transfer in axisymmetric quartz glass tubes

A mathematical model is proposed to describe the heat transfer in quartz glass axisymmetric tubes. Heat is transferred inside the glass by radiation and conduction. Scattering of thermal radiation inside the glass is ignored. At the boundaries of the tube the radiative intensity is specularly reflected. The spectral dependent radiative intensity and the temperature distribution inside the tube are determined. The model is applied to simulate the cooling process of a quartz glass tube. The calculated temperature is in agreement with that obtained from an experiment. Furthermore, steady-state temperature distributions in quartz glass tubes of different lengths have been determined.     

用行波速率方程组确定半导体激光器的输出场

为了解决在平均场近似速率方程中自洽地由激光器腔内平均场来确定输出场的问题,以半导体激光器为例,采用集总形式的端面反射率,通过求解行波速率方程组,得出了半导体激光器腔内平均光子数密度与输出光子数密度的解析关系式.结果表明,半导体激光器输出场与腔内平均场之比是一个与泵浦电流有关的量,把它当成常数是有偏见的.     

一种准二维柱面爆炸波加载装置的设计与验证

基于竖直爆轰管和径向Hele-Shaw Cell,设计并搭建了一套准二维柱面爆炸波加载装置,可以实现对Hele-Shaw Cell内部材料界面的径向冲击加载.竖直爆轰管内部的预混气体在底部点燃后,形成向上传播的冲击波,冲击波冲破爆轰管开口与Hele-Shaw Cell底板开孔之间的隔膜后,被Hele-Shaw Cell...