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排序方式: 共有251条查询结果,搜索用时 15 毫秒
1.
Z Ma S Ramanadham K Kempe Z Hu J Ladenson J Turk 《Canadian Metallurgical Quarterly》1996,1308(2):151-163
We prepared polymers having a phospholipid polar group, poly [omega-methacryloyloxyalkyl phosphorylcholine (MAPC)-co-n-butyl methacrylate(BMA)], as new biomedical materials and evaluated their blood compatibility with attention to protein adsorption and platelet adhesion. The total amount of proteins adsorbed on the polymer surface from human plasma was determined, and the distribution of adsorbed proteins on the plasma-contacting surface was analyzed. The amount of proteins adsorbed on every poly (MAPC-co-BMA) was small compared with that observed on polymers without the phospholipid polar group. However, there was no significant difference in the amount of adsorbed proteins on the poly(MAPC-co-BMA) even when the methylene chain length between the phospholipid polar group and the backbone in the MAPC moiety was altered. Platelet adhesion on the polymer surface from a platelet suspension in a buffered solution was evaluated with and without plasma treatment on the surface. When a rabbit platelet suspension was brought into contact with the poly(BMA) surface after treatment with plasma, many platelets adhered and aggregated. However, a reduced amount of platelet adhered on the poly(BMA) was found in the case of direct contact with the platelet suspension. On the other hand, the poly(MAPC-co-BMA)s could inhibit platelet adhesion under both conditions. Based on these results, it can be concluded that the proteins adsorbed on the surface play an important role in determining the platelet adhesion and suppression of the protein adsorption on the surface, which is one of the most significant ways of inhibiting platelet adhesion. 相似文献
2.
The recent demonstration that myocardial Ca(2+)-independent phospholipase A2 exists as a complex of catalytic and regulatory polypeptides that is modulated by ATP has suggested a novel mechanisms through which alterations in glycolytic flux can be coupled to the generation of eicosanoids which facilitate insulin secretion. To determine the potential relevance of this mechanism, we examined the kinetic characteristics, substrate specificities, and cellular locus of phospholipase A2 activity in pancreatic islets. Rat pancreatic islets contain a Ca(2+)-independent phospholipase A2 activity which is optimal at physiologic pH, preferentially hydrolyzes phospholipid substrates containing a vinyl ether linkage at the sn-1 position, and prefers arachidonic acid compared to oleic acid in the sn-2 position. Rat islet Ca(2+)-independent phospholipase A2 activity is inhibited by the mechanism-based inhibitor (E)-6-(bromomethylene)-3-(1-naphthalenyl)-2H-tetrahydropyran-2-one and is stimulated by ATP. Purification of beta-cells from dispersed pancreatic islet cells by fluorescence-activated cell sorting demonstrated that beta-cells (but not non-beta-cells) contain Ca(2+)-independent, ATP-stimulated phospholipase A2 activity. Remarkably, clonal RIN-m5f insulinoma cells, which possess a defect in glucose-induced insulin secretion, contain a Ca(2+)-independent phospholipase A2 which is not modulated by alterations in ATP concentration. Collectively, these results and those of an accompanying paper [Ramanadham et al. (1993) Biochemistry (following paper in this issue)] implicate Ca(2+)-independent phospholipase A2 as a putative glucose sensor which can couple alterations in glycolytic metabolism to the generation of biologically active eicosanoids and thereby facilitate glucose-induced insulin secretion. 相似文献
3.
E Zerovnik R Jerala R Virden L Kroon Zitko V Turk JP Waltho 《Canadian Metallurgical Quarterly》1998,32(3):304-313
In this report, we demonstrate the utility of interleukin-2 (IL-2) stimulation of spleen cell cultures and bivariate flow cytometry in the analysis and purification of the C57BL/6J mouse Y Chromosome. We determined that the DNA content of the C57BL/6J Y Chromosome is approximately 94.7 Mb, making it similar in size to human Chromosome 16 and significantly larger than previous estimates. In addition, we describe the bulk isolation of mouse Y Chromosomes and demonstrate enrichment of the isolated material using a fluorescence in situ hybridization strategy. We detail the construction of two small insert Y Chromosome-specific libraries, ideal for sampling Y Chromosome sequences. From these libraries 1566 clones were analyzed. We provide a detailed characterization of 103 clones, generating nearly 50 kb of sequence. For 30 of these clones, we identify regions of homology to known Y chromosomal sequences, confirming the enrichment of the sorted DNA. From the remaining characterized clones, we describe the development of 15 male-specific PCR assays and 19 male-female PCR assays potentially originating from the pseudoautosomal region or other areas of X-Y or autosome-Y homology. 相似文献
4.
Ian Turk Matthew Sin Xin''an Zhou Jun Tao Chaoli Wang Qi Liao 《International Journal of Software and Informatics》2016,10(3)
We present a visual analytics system to understand the operation data of a
company, GAStech, from IEEE VAST Challenge 2016. The data include proximity data
recording the locations and movements of employees, and heating, ventilation, and air
conditioning (HVAC) data recording the environmental conditions in the building.
Analyzing the data to detect the suspicious behaviors of some disgruntled employees is of
special interest. Our system provides coordinated multiple views to visualize the proximity
data and the HVAC data over time. Visual hints and comparisons are designed for users to
identify abnormal patterns and compare them. Furthermore, the system automatically
detects and correlates the anomalies in the data. We provide use cases to demonstrate the
effectiveness of our system. 相似文献
5.
In the course of their small angle x-ray scattering work, Winslow and Diamond also calculated the radius of gyration of the pores. Using its value for a paste, Diamond adopted two models for the average pore: a sphere and a cylinder of equal height and diameter. This model leads to absurd values for the surface area of the paste. Using a cylindrical model, and the radius of gyration plus the hydraulic radius, the present authors calculated for a similar paste the dimensions of the average pore and obtained the values: . The number of pores per gram of paste was 2.26 × 1017. The paper also discusses the surface area of hardened paste, and points out the extremely important contributions of Winslow and Diamond to the subject. 相似文献
6.
Kwatra Nipun Wojtan Chris Carlson Mark Essa Irfan A. Mucha Peter J. Turk Greg 《IEEE transactions on visualization and computer graphics》2010,16(1):70-80
We present an algorithm for creating realistic animations of characters that are swimming through fluids. Our approach combines dynamic simulation with data-driven kinematic motions (motion capture data) to produce realistic animation in a fluid. The interaction of the articulated body with the fluid is performed by incorporating joint constraints with rigid animation and by extending a solid/fluid coupling method to handle articulated chains. Our solver takes as input the current state of the simulation and calculates the angular and linear accelerations of the connected bodies needed to match a particular motion sequence for the articulated body. These accelerations are used to estimate the forces and torques that are then applied to each joint. Based on this approach, we demonstrate simulated swimming results for a variety of different strokes, including crawl, backstroke, breaststroke, and butterfly. The ability to have articulated bodies interact with fluids also allows us to generate simulations of simple water creatures that are driven by simple controllers. 相似文献
7.
Kar-Han Tan Feris R.S. Turk M. Kobler J. Jingyi Yu Raskar R. 《Computer Graphics and Applications, IEEE》2005,25(1):32-38
A method for capturing geometric features of real-world scenes relies on a simple capture setup modification. The system might conceivably be packaged into a portable self-contained device. The multiflash imaging method bypasses 3D geometry acquisition and directly acquires depth edges from images. In the place of expensive, elaborate equipment for geometry acquisition, we use a camera with multiple strategically positioned flashes. Instead of having to estimate the full 3D coordinates of points in the scene (using, for example, 3D cameras) and then look for depth discontinuities, our technique reduces the general 3D problem of depth edge recovery to one of 2D intensity edge detection. Our method could, in fact, help improve current 3D cameras, which tend to produce incorrect results near depth discontinuities. Exploiting the imaging geometry for rendering provides a simple and inexpensive solution for creating stylized images from real scenes. We believe that our camera will be a useful tool for professional artists and photographers, and we expect that it will also let the average user easily create stylized imagery. This article is available with a short video documentary on CD-ROM. 相似文献
8.
Observations of tropical cyclone structure from WindSat 总被引:1,自引:0,他引:1
Turk F.J. DiMichele S. Hawkins J. 《Geoscience and Remote Sensing, IEEE Transactions on》2006,44(3):645-655
Passive microwave (PMW) radiometric observations of clouds from multichannel imaging sensors onboard low Earth-orbiting environmental satellites are now a vital operational dataset. The first operational passive microwave sensor was the Special Sensor Microwave/Imager onboard the Defense Meteorological Satellite Program satellites, which has been gathering hydrological data records since 1987, and continued with the Tropical Rainfall Measuring Mission (TRMM) and the Advanced Microwave Scanning Radiometer onboard Aqua. These sensors view the underlying scene with an Earth incidence angle near 53/spl deg/ and with a variable azimuthal angle, depending upon the orbit direction and scan position. The WindSat sensor onboard the Coriolis satellite, launched in January 2003, is a five-channel polarimetric PMW radiometer designed to optimize ocean surface wind vector retrievals. While it does not have 85-GHz channels, an added feature is its unique fore-aft viewing capability across a portion of its fore scan swath. This provides a view of the underlying scene from two separate azimuthal directions, which provides added information on the three-dimensional (3-D) structure of clouds and their evolution. In this paper, we compare WindSat and TRMM Precipiation Radar observations of tropical cyclones (TCs) with Monte Carlo radiative transfer simulations performed on idealized 3-D convective cloud structures. The TC 3-D structure and possible tilt in the convective cloud structure are inferred from the difference between the 37-GHz equivalent blackbody brightness temperatures (T/sub B/) from the corresponding fore and aft view observations. The information gained from this analysis is important since asymmetries in the cloud vertical and horizontal structure may be an indication of upper level wind shear, which plays a major role in influencing changes of the TC intensity. 相似文献
9.
Huong Quynh Dinh Turk G. Slabaugh G. 《IEEE transactions on pattern analysis and machine intelligence》2002,24(10):1358-1371
We present a new method of surface reconstruction that generates smooth and seamless models from sparse, noisy, nonuniform, and low resolution range data. Data acquisition techniques from computer vision, such as stereo range images and space carving, produce 3D point sets that are imprecise and nonuniform when compared to laser or optical range scanners. Traditional reconstruction algorithms designed for dense and precise data do not produce smooth reconstructions when applied to vision-based data sets. Our method constructs a 3D implicit surface, formulated as a sum of weighted radial basis functions. We achieve three primary advantages over existing algorithms: (1) the implicit functions we construct estimate the surface well in regions where there is little data, (2) the reconstructed surface is insensitive to noise in data acquisition because we can allow the surface to approximate, rather than exactly interpolate, the data, and (3) the reconstructed surface is locally detailed, yet globally smooth, because we use radial basis functions that achieve multiple orders of smoothness. 相似文献
10.
The existence of a precursor of cathepsin D: evidence from autolysis, denaturation and activation studies 总被引:1,自引:0,他引:1
This report evidences that the single polypeptide chain of cathepsin D undergoes in vitro autolysis resulting in heavy (Mr about 30000) and light (Mr about 15000) polypeptide chains. These two chains are held together through non-covalent interaction, thus constituting a stable active conformation. Fluorescence and circular dichroism measurements demonstrate the irreversible denaturation of cathepsin D. The existence of cathepsin D precursor, cathepsinogen D, of about 50000 molecular weight was proved. Cathepsinogen D is converted to the active enzyme by intramolecular activation, releasing activation-inhibitory peptide(s). 相似文献