RADIATION-INDUCED CRYSTAL DEFECTS IN PTFE

Changes induced in the crystal structure of PTFE by irradiation at different temperatures have been investigated. In the dose and temperature range examined, the density of PTFE was observed to increase continuously with increasing dose due to the radiation-induced increase in crystallinity, while after post-irradiation annealing at 380-degrees-C, the density was observed to increase for samples irradiated at 20-degrees-C, and to begin to decrease after a certain dose for samples irradiated at 150 and 200-degrees-C. On the basis of the observation of radiation-induced separation of the melting peak of PTFE and its stability relative to the change in the rate of heating, the observed decrease in density was explained as being due to the radiation-induced crosslinking and/or branching inhibiting the process of crystallization and existing in the crystalline region as defects.

Suppression of zebrafish VEGF gene by cytomegalovirus promoter-driven short hairpin constructs induces vascular development defects and down regulation NRP1 expression

The usage of RNA interference for gene knockdown in zebrafish through expression of the small interfering RNA mediators from DNA vectors has created a lot of excitement in the research community. In this work, the ability of human cytomegalovirus immediate early promoter (CMV promoter)-driven short hairpin RNA (shRNA) expression vector to induce shRNA against vascular endothelial growth factor (VEGF) gene in zebrafish was tested, and its effects on VEGF-mediated vasculogenesis and angiogenesis were evaluated. Altogether four vectors targeting various locations of VEGF gene were constructed, and pSI-V4 was proven to be the most effective one. Microinjection of pSI-V4 into the zebrafish embryos resulted in defective vascular formation and down regulation of VEGF expression. In situ hybridization analysis indicated that silencing VEGF gene expression by pSI-V4 resulted in down regulation of neuropilin-1 (NRP1), a potent VEGF receptor. Knockdown of VEGF expression by morpholino gave the same result. This provided evidence that the VEGF-mediated angiogenesis in zebrafish was in part dependent on NRP1 expression. The results contributed to a better understanding of molecular mechanisms of cardiovascular development and provided a potential promoter for making inducible knockdown in zebrafish.

VEGF gene silencing by cytomegalovirus promoter driven ShRNA expression vector results in vascular development defects in zebrafish

Zebrafish has been generally considered as an excellent model in case of drug screening, disease model establishment, and vertebrate embryonic development study. In this work, the ability of human cytomegalovirus immediate early promoter (CMV promoter)-driven short hairpin RNA (shRNA) expression vector to induce shRNA against VEGF gene in zebrafish was tested, and its effect on vascular development was assed, too. Using RT-qPCR, blood vessel staining, and in situ hybridization, we confirmed certain transcriptional activity and down regulation of gene expression by the vector. In situ hybridization analysis indicated selective inhibition of NRP1 expression in the VEGF gene loss of function model, which might imply in turn that VEGF could not only activate endothelial cells directly but also could contribute to stimulating angiogenesis in vivo by a mechanism that involved up-regulation of its cognate receptor expression in zebrafish. This contributed to a better understanding of molecular mechanisms of cardiovascular development. The system improved the success rate in making inducible knockdown and widened the possibilities for better therapeutic targets in zebrafish.

Joint statistical distribution of two-point sea surface elevations in finite water depth

Based on the second-order random wave solutions of water wave equations in finite water depth, a joint statistical distribution of two-point sea surface elevations is derived by using the characteristic function expansion method. It is found that the joint distribution depends on five parameters. These five parameters can all be determined by the water depth, the relative position of two points and the wave-number spectrum of ocean waves. As an illustrative example, for fully developed wind-generated sea, the parameters that appeared in the joint distribution are calculated for various wind speeds, water depths and relative positions of two points by using the Donelan and Pierson spectrum and the nonlinear effects of sea waves on the joint distribution are studied. (C) 2003 Elsevier B.V. All rights reserved.

构造复杂区变速成图方法研究

In the complex structure areas, velocity field building and structure mapping are important for seismic exploration. With the development of seismic exploration, the methods of structure mapping, reservoir prediction and reservoir description all require high precious velocity field. And more accurate depth-structure maps are required for well site design. Aiming at the problems and defects in velocity analysis and structure mapping in oil seismic exploration, the paper which is based on the studies of real data in several areas combines the theories with practical application, and analyzes the precision and applicability of several methods of velocity model building. After that, the following methods are mainly studied: the coherence inversion methods based on the pre-stack CMP gathers or stacking velocity; the interval velocity inversion methods constrained by multi-well; the Random Simulation method; 3D Image Ray Map Migration method and the structure mapping in floating datum and in fixed datum, and then we conclude the method of building high precious seismic velocity field and structure mapping with variable velocity. Firstly, the paper analyses the distributing rule of the velocity variation in the areas with complex structures in the northwest of China, then points out that velocity is a crucial factor which influences the precision of structure mapping, and the velocity variations have something to do with the shapes of the structures, the variety of lithology and so on. The key point of improving the precision of seismic velocity field is to obtain a structure mapping with high precision. We also describe the range and conditions of these methods. Secondly, by comparing many popular methods of velocity model building, we propose a new method in the use of velocity model building. The new method is more effective in velocity model building under every kind of complex condition and is worthy of spreading. At last, the paper fingers out that it is a system engineering to study variable velocity mapping in every kind of complex structure areas. Every step of the work can affect the final results. So it is important to build high efficient and practical velocity model and the flows of mapping processing. The paper builds the flows and gives some examples. The method has been applied in more than ten exploring surveys. The application proves that this method could bring good effect on researching on low-amplitude trap, reservoir prediction, reservoir description and the integrated research of oil&gas geology. Keywords: structure mapping velocity model building complex structure variable velocity media

Direct observation of subsurface oxygen on the defects of Pd(100)

Oxygen adsorption and desorption on a Pd(100) surface with a mesoscopic defect were studied by photoemission electron microscopy (PEEM). The defect surface, with an area of approximately 200 x 60 mu m(2), behaved differently from the perfect Pd(100) surface towards the adsorption of oxygen. When saturated, both surface oxygen and subsurface oxygen coexisted on the defect surface, whereas only surface oxygen was present on the Pd(100) surface. Upon heating, subsurface oxygen diffused back to the surface and desorbed with surface oxygen at the same time. The difference in oxygen adsorption ability between the defect surface and the perfect Pd(100) surface can be attributed to different structures of these two surfaces. (C) 1999 Elsevier Science B.V. All rights reserved.

The magnetic structure of a coronal X-ray bright point

Brown, D.S., Parnell, C.E., Deluca, E., McMullen, R. and Golub, L., 2001, The magnetic structure of a coronal X-ray bright point, Solar Physics, 201, 305-321.

Automatic point correspondence and registration based on linear structures

R. Marti, R. Zwiggelaar, C.M.E. Rubin, 'Automatic point correspondence and registration based on linear structures', International Journal of Pattern Recognition and Artificial Intelligence 16 (3), 331-340 (2002)

Who has the Right to Govern Online Activity? A Criminal and Civil Point of View

Kohl, U. (2004). Who has the right to govern online activity? A criminal and civil point of view. International Review of Law, Computers & Technology 18 (3), 387-410 RAE2008

'Citizen of nowhere' or 'the point where circles intersect'? Impartialist and embedded cosmopolitanisms?

Erskine, Toni, 'Citizen of nowhere' or 'the point where circles intersect'? Impartialist and embedded cosmopolitanisms', Review of International Studies (2002) 28(3) pp.457-477 RAE2008

The aesthetics of he eyes and mouth position in a three-point face schema

Oculographical research of people watching a human face indicates than beholder's eyes stop most often and for the longest period of time on the eyes and the mouth of the face looked at and that they move among these three points most frequently. The position of the eyes and mouth in relation to one another can be described with a single number being a measure of an angle with the vertex in the middle of the mouth and with arms crossing the centers of the eye pupils. The angles were measured from photographs of people from all over the world, as well as of residents of Lublin. Subsequently, the subjects from Lublin were asked to make face schemas by positioning the eyes and the mouth in the way they considered most attractive. The eye-mouth-eye angle of these schemas was measured. Additionally, measurements of the same angle were taken from the faces depicted in icons. The schemas of the most attractive - according to the subjects - faces were characterized by angles approximating the mean angle from the photographs, and significantly greater than the mean angle from the icons.