养生重点在“三间”

自我保健应该贯穿整个人生。从少年时代懂得“自我保护”时开始,一直到人生的终点。在一天二十四小时之内,除了睡着以外,每时每刻都应该注意保护自己的身体。

基于“三间距离”理论概念的旅游客源市场开发研究——以江门市为例

江门旅游客源市场有着巨大挖掘潜力,特提出用三间距离理论作为指导江门旅游客源市场开发的指导思想,提出要充分认识三间距离的互动作用,有针对性开拓不同距离的游客市场,利用各种媒介对特色旅游景点宣传,打造特色拳头旅游产品,构建更加完善的旅游环境等措施。

Three-dimensional conjugate gradient inversion of magnetotelluric sounding data

Based on the analysis of the conjugate gradient algorithm, we implement a threedimensional （3D） conjugate gradient inversion algorithm with magnetotelluric impedance data. During the inversion process, the 3D conjugate gradient inversion algorithm doesn＇ t need to compute and store the Jacobian matrix but directly updates the model from the computation of the Jacobian matrix. Requiring only one forward and four pseudo-forward modeling applications per frequency to produce the model update at each iteration, this algorithm efficiently reduces the computation of the inversion. From a trial inversion with synthetic magnetotelluric data, the validity and stability of the 3D conjugate gradient inversion algorithm is verified.

The numerical simulation for a 3D two-phase anisotropic medium based on BISQ model

Biot-flow and squirt-flow are the two most important fluid flow mechanisms in porous media containing fluids. Based on the BISQ （Biot-Squirt） model where the two mechanisms are treated simultaneously, the elastic wave-field simulation in the porous medium is limited to two-dimensions and two-components （2D2C） or two-dimensions and three-components （2D3C）. There is no previous report on wave simulation in three- dimensions and three-components. Only through three dimensional numerical simulations can we have an overall understanding of wave field coupling relations and the spatial distribution characteristics between the solid and fluid phases in the dual-phase anisotropic medium. In this paper, based on the BISQ equation, we present elastic wave propagation in a three dimensional dual-phase anisotropic medium simulated by the staggered-grid high-order finite-difference method. We analyze the resulting wave fields and show that the results are an improvement.

屈原是伟大的人民教育家(一)──屈原的教育实践

湖湘文化源远流长。澧县“彭头山文化遗址”和“城头山文化遗址”的出土，用铁的事实证实，湖南洞庭湖地区是中华民族文化的摇篮之一，很多方面比黄河流域还早。屈原就是先秦湖湘文化集大成者。他不仅是位伟大思想家、政治家、文学家，而且是位伟大人民教育家。本刊将全面介绍屈原从事教育方面的业绩，以抛砖引玉，望能引起专家学者对这方面注意和研究。

High-level Stark Effect and Spectrum of Spherical Nanometer System

In the electric field and layer-to-layer interaction energy, the law of split-level of high-level Stark effect of spherical nanometer system is explored as well as the frequency of spectrum, intensity and size effect of coefficient of spontaneous radiation. Taking three layers CdS/HgS spherical nanometer system as an example, the influence of the electric field and layer-to- layer interaction energy is explored on Stark effect and spectrum. The results show that in the Stark effect system, the energy level is split based on 1, 3, ..., （2n-1）, when it is in the electric field only, similar to the hydrogen atoms; and in the electric field and layer-to-layer interaction, it is split based on 1, 4, ~ -., n2; with the quantum transition, the frequency of the spectrum decreases with the increasing size of the system; apart from a few spectral lines, the intensity of most spectral lines will decreased as the size increases; while the coefficient of spontaneous radiation will increase with the increasing size; the electric field will cause the changes of spectrum frequency; its spectrum frequency shift is proportional to the square of the electric field intensity; apart from a few spectral lines, the frequency shift of spectral lines that is caused by the electric field and layer-to-layer interaction will decrease as the size increases; the interaction will make the level of electronic energy level lower slightly （the order of magnitude is between 10-7-10-9 eV）, the slightly increased spectrum intensity and the slightly increased value of coefficient of spontaneous radiation, but it will not influence the frequency of spectrum, intensity, and the trend that coefficient of spontaneous radiation changes with the size; when the size is smaller, the layer-to-layer interaction effect will be significant.

Simulation Study of the Workspace of the Parallel Machine Tool

A new three dimensional simulation method is introduced to study the workspace of a 6 PSS (P denotes a prismatic kinematic pair, S denotes a spherical kinematic pair) parallel machine tool. This algorithm adopts the method of numerical analysis to investigate the boundary points in a series of sections which form the surface of the workspace. That is, to study such points that have the largest polar radius on a certain section in a system of polar coordinates according to conditions of constraint. The constraint conditions considered in the article include the maximum and minimum displacements of each dieblock, the maximum and minimum angles of oscillation in each hinge. By converting the constraint inequalities into constraint equations, the largest polar radius corresponding to every constraint condition can be evaluated and the minimum one is used to decide the boundary point. This algorithm greatly simplifies the computational process and can be used to analyze any section of the workspace. It provides a theoretical basis for the structural design of such a machine tool.

OSMOTIC STRESS DECREASES THE ACTIVITY OF ATPASE ASSOCIATED WITH THE ROOT CAP PLASMODESMATAIN ZEA MAYS

With light and electron microscopy the substructural change and the ATPase activity of corn (Zea mays L.) root cap cells after short-term osmotic stress were studied. Some spoke-like fine strands originating from the departed periplasm and stretching towards cell wall could be observed even after plasmolysis. By observing the precipitation of ATPase activity product (lead phosphate) at plasma membrane and plasmodesmata, it was found that the fine strands were plasma membrane-lined channels surrounding the cytoplasm and that they still firmly connected to the plasmodesmata during plasmolysis. Compared with the control (unstressed), a sharp decrease of ATPase activity in the plasmodesmata of the stressed cells was observed. Inhibition of energy metabolism in these limited locales would affect the physiological activity, maybe including the regulation of permeability and the change of size exclusion limit (SEL) of plasmodesmata.

养生重点在三间

自我保健应该贯穿整个一生,从少年时代懂得“自我保护”时开始,一直到人生的终点。在一天24小时之内,除了睡眠以外,每时每刻都应该注意保护自己的身体。 不过,一天之中,最适宜养生的重点时间应该是“三间”——晨间、午间和晚间。有人称之为养生的“焦点时刻”。科学研究和实践—

Nonlinear Optical Properties of Al-Doped nc-Si-SiO_2 Composite Films

The nonlinear optical properties of Al-doped nc-Si-SiO2 composite films have been investigated using the time-resolved four-wave mixing technique with a femtosecond laser. The off-resonant third-order nonlinear susceptibility is observed to be 1.0 × 10-10 esu at 800nm. The relaxation time of the optical nonlinearity in the films is as short as 60fs. The optical nonlinearity is enhanced due to the quantum confinement of electrons in Si nanocrystals embedded in the SiO2 films. The enhanced optical nonlinearity does not originate from Al dopant because there are no Al clusters in the films.

Preparation and characterization of ternary magnetic g-C_3N_4 composite photocatalysts for removal of tetracycline under visible light

A stable PNIPAM/Fe_3O_4/g-C_3N_4 composite photocatalyst was designed and prepared by a thermal photoinitiation technology.The structure and properties of the materials were characterized and the composite photocatalyst was found to show good stability for tetracycline degradation.The sample not only retained the magnetic properties of Fe_3O_4,allowing it to be recycled,but its photocatalytic properties could also be changed by controlling the temperature of the reaction system.The degradation intermediate products of tetracycline were further investigated by MS.This work provides a new facile strategy for the development of intelligent and recyclable photocatalytic materials.

Three-dimensional arbitrarily anisotropic modeling for time-domain airborne electromagnetic surveys

Electrically anisotropic strata are abundant in nature, so their study can help our data interpretation and our understanding of the processes of geodynamics. However, current data processing generally assumes isotropic conditions when surveying anisotropic structures, which may cause discrepancies between reality and electromagnetic data interpretation. Moreover, the anisotropic interpretation of the time-domain airborne electromagnetic （TDAEM） method is still confined to one dimensional （1D） cases, and the corresponding three-dimensional （3D） numerical simulations are still in development. In this study, we expanded the 3D TDAEM modeling of arbitrarily anisotropic media. First, through coordinate rotation of isotropic conductivity, we obtained the conductivity tensor of an arbitrary anisotropic rock. Next, we incorporated this into Maxwell＇s equations, using a regular hexahedral grid of vector finite elements to subdivide the solution area. A direct solver software package provided the solution for the sparse linear equations that resulted. Analytical solutions were used to verify the accuracy and feasibility of the algorithm. The proven model was then applied to analyze the effects of arbitrary anisotropy in 3D TDAEM via the distribution of responses and amplitude changes, which revealed that different anisotropy situations strongly affected the responses of TDAEM.

Raman Scattering at Resonant or Near-Resonant Conditions： A Generalized Short-Time Approximation

We investigate the dynamics of resonant Raman scattering in the course of the frequency de- tuning. The dephasing in the time domain makes the scattering fast when the photon energy is tuned from the absorption resonance. This makes frequency detuning to act as a camera shutter with a regulated scattering duration and provides a practical tool of controlling the scattering time in ordinary stationary measurements. The theory is applied to resonant Raman spectra of a couple of few-mode model systems and to trans-1,3,5-hexatriene and guanine-cytosine （G-C） Watson-Crick base pairs （DNA） molecules. Besides some particular physical effects, the regime of fast scattering leads to a simplification of the spectrum as well as to the scattering theory itself. Strong overtones appear in the Raman spectra when the photon frequency is tuned in the resonant region, while in the mode of fast scattering, the overtones are gradually quenched when the photon frequency is tuned more than one vibra- tional quantum below the first absorption resonance. The detuning from the resonant region thus leads to a strong purification of the Raman spectrum from the contamination by higher overtones and soft modes and purifies the spectrum also in terms of avoidance of dissociation and interfering fluorescence decay of the resonant state. This makes frequency detuning a very useful practical tool in the analysis of the resonant Raman spectra of complex systems and considerably improves the prospects for using the Raman effect for detection of foreign substances at ultra-low concentrations.

Clinical value of CT three-dimensional imaging in diagnosing gastrointestinal tract diseases

AIM： To discuss the clinical value of CT three-dimensional （3-D） imaging in diagnosing gastrointestinal tract diseases.METHODS： Three-D imaging findings of 52 patients were retrospectively analyzed. Three-D imaging methods included shaded surface display （SSD）, volume rendering （VR）, virtual endoscopy （VE） and multiplanar reformatting （MPR）. The diagnosis results of CT 3-D were evaluated by comparison with those of endoscopy and/or surgical finding.RESULTS： Fifty-two patients with gastrointestinal tract diseases were diagnosed by CT 3-D imaging, of whom 50 cases were correctly diagnosed and 2 were misdiagnosed. There were 33 cases of gastric diseases （27 with carcinoma, 5 with peptic ulcer and 1 with leiomyoma） and 19 large intestinal diseases （10 with colon carcinoma, 2 with carcinoma of the rectum, 5 with colon polypus and 2 with tuberculosis of the ileocecal junction）. Twenty-two cases with prominent lesions （9 with subsequent hollow lesions）, 20 with stenosis of cavity （8 with concomitant prominent lesions） and 10 with hollow lesions （5 with concomitant prominent lesions） were shown in 3-D images. The minimal lesion shown was 1.0 cm × 0.8 cm × 0.5 cm.CONCLUSION： CT 3-D imaging, a non-invasive examination without pain, can display clearly and directly the lesions of gastrointestinal tract with accurate location and high diagnosis accuracy. It is an important complementary technique to endoscopy.

From 2D to 3D GIS for CyberCity

In order to understand the 3D landscape with many h igh buildings in a city, the 2D GIS has to be extended to 3D GIS. The further de velopment of CyberCity has to include various applications of 3D scenes from the outdoor scenes to the indoor ones. In thispaper, some key techniques, such as data management method and dynamicalvisualization method for the outdoor and the indoor scenes, are discussed.The indoor scene is compared with the outdoor one. The idea of integratedrepresentation of the outdoor and the indoor scenes in CyberCity GIS is discusse d.

New Exact Solutions and Conservation Laws to （3＋1）-Dimensional Potential-YTSF Equation

Using the modified find some new exact solutions to Lie point symmetry groups and also get conservation laws, of the CK＇s direct method, we build the relationship between new solutions and old ones and the （3＋1）-dimensional potentiaial-YTSF equation. Baaed on the invariant group theory, Lie symmetries of the （3＋1）-dimensional potential-YTSF equation are obtained. We equation with the given Lie symmetry.

3D electrical resistivity inversion using prior spatial shape constraints

To minimize the number of solutions in 3D resistivity inversion, an inherent problem in inversion, the amount of data considered have to be large and prior constraints need to be applied. Geological and geophysical data regarding the extent of a geological anomaly are important prior information. We propose the use of shape constraints in 3D electrical resistivity inversion, Three weighted orthogonal vectors （a normal and two tangent vectors） were used to control the resistivity differences at the boundaries of the anomaly. The spatial shape of the anomaly and the constraints on the boundaries of the anomaly are thus established. We incorporated the spatial shape constraints in the objective function of the 3D resistivity inversion and constructed the 3D resistivity inversion equation with spatial shape constraints. Subsequently, we used numerical modeling based on prior spatial shape data to constrain the direction vectors and weights of the 3D resistivity inversion. We established a reasonable range between the direction vectors and weights, and verified the feasibility and effectiveness of using spatial shape prior constraints in reducing excessive structures and the number of solutions. We applied the prior spatially shape-constrained inversion method to locate the aquifer at the Guangzhou subway. The spatial shape constraints were taken from ground penetrating radar data. The inversion results for the location and shape of the aquifer agree well with drilling data, and the number of inversion solutions is significantly reduced.