时空连续统中的颜色和显示

一种在空间域和时间域进行混色处理的合成显示颜色的新方法，能提高图像质量，改善彩色显示器的性能。     

Analytical comparison of sensor signal processing enhancements forNDT synthetic aperture ultrasonic imaging

The results of a detailed analytical study of the effects of sensor processing techniques on clutter suppression and image enhancement for nondestructive testing (NDT) systems are presented. A relatively simple beamforming/diffraction model is developed for near-field, wideband, synthetic aperture ultrasonic imaging in NDT systems. The physical model is used to quantitatively evaluate a variety of front-end sensor signal processing tradeoffs for the enhanced detection and sizing of defects. It is shown using statistical microscopic scattering calculations that a combination of increased spatial sampling and rectangular windowing can increase the signal-to-clutter ratio by ~10 dB while maintaining crack size resolutions well below future projected specifications. The sensor signal processing image enhancements are demonstrated by the construction of simulated strip-map SAFT (synthetic aperture focusing technique) images of metallic crack defects in the presence of large numbers of randomly distributed clutter (simulated grain boundary) scatterers.     

The evaluation of argon laser photocoagulation in a series of animal models of upper gastrointestinal bleeding

During the past five years we have evaluated argon laser photocoagulation in various canine models of upper gastrointestinal hemorrhage. In gastric erosions, the eight-watt argon laser was uniformly effective in stopping bleeding. In our standard acute ulcer model the seven-watt argon laser was effective in stopping bleeding from most ulcers and only occasionally produced deep injury. With the addition of a jet of CO2 exiting the laser catheter coaxial to the laser beam, the argon laser was 100% effective and no deep injury resulted. The application of the argon laser in a more physiologic canine bleeding model using a single bleeding vessel in an ulcer base is currently under study. The development of improved animal models of gastrointestinal bleeding should contribute to the identification of effective and safe endoscopic hemostatic methods.     

Locus of control and mastery in a reformatory: A field study of defensive externality.

145 males (mean age 21.9 yrs) enrolled in an incentive-based reformatory were administered Rotter's Internal–External Locus of Control (LOC) Scale, Marlowe–Crowne Social Desirability Scale, and several measures of expectancy/importance of success and failure. After success or failure at mastery attempts, Ss made causal attributions derived from both J. B. Rotter's (1966) and B. Weiner's (1972) theories. Results show that internal LOC inmates, relative to externals, demonstrated greater mastery and attributed more responsibility to themselves for success, even with social desirability controlled. Defensive externality hypotheses involving both major moderators of LOC, interpersonal trust and action taking, as well as 4 proposed aspects of defensive externality were not supported. Contrary to predictions, trust-defensive externals made more internal nondefensive attributions after failure than trust-congruent externals did. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ultrasound scattering model: 2-D cross-correlation and focusing criteria--theory, simulations, and experiments

A microscopic scattering model is developed to expedite simulation studies of ultrasound imaging in soft tissue using multichannel transducer probes. The model fully accounts for the physics of broadband signals, propagating wave packets, and time delay focusing. Analytical results are presented for 2-D transducer arrays; 1-D results can be trivially extracted by setting the number of rows equal to unity. The 2-D cross-correlation and the 2-D form of the Mallart-Fink (MF) focusing factor are calculated. It is demonstrated that the scattering model reduces to the 2-D form of the monochromatic van Cittert Zernike (VCZ) analysis. Simulation results for the focusing factor are presented, and comparisons are given between the values obtained from simulation, analytical theory, and actual water tank experiments. The comparative results are ail in close accord with each other     

Three distinct D-amino acid substitutions confer potent antiangiogenic activity on an inactive peptide derived from a thrombospondin-1 type 1 repeat

Mal II, a 19-residue peptide derived from the second type 1 properdin-like repeat of the antiangiogenic protein thrombospondin-1 (TSP-1), was inactive in angiogenesis assays. Yet the substitution of any one of three L-amino acids by their D-enantiomers conferred on this peptide a potent antiangiogenic activity approaching that of the intact 450-kDa TSP-1. Substituted peptides inhibited the migration of capillary endothelial cells with an ED50 of 8.5 nM for the D-Ile-15 substitution, 10 nM for the D-Ser-4 substitution, and 0.75 nM for the D-Ser-5 substitution. A peptide with D-Ile at position 15 could be shortened to its last seven amino acids with little loss in activity. Like whole TSP-1, the Mal II D-Ile derivative inhibited a broad range of angiogenic inducers, was selective for endothelial cells, and required CD36 receptor binding for activity. A variety of end modifications further improved peptide potency. An ethylamide-capped heptapeptide was also active systemically in that when injected i.p. it rendered mice unable to mount a corneal angiogenic response, suggesting the potential usefulness of such peptides as antiangiogenic therapeutics.     

YBCO nanofibers synthesized by electrospinning a solution of poly(acrylic acid) and metal nitrates

A versatile approach to the synthesis of YBCO (high temperature superconductor ceramics) nanofibers via electrospinning a polymer precursor solution is reported. The aqueous polymer precursor solution consists of poly(acrylic acid) (PAAc) and a mixture of yttrium nitrate, barium nitrate, and copper nitrate, henceforth termed (Y,Ba,Cu)–N. The conductivity of the polymer precursor solution at 27.1 °C was 14.70 mS/cm, its zero shear viscosity was 52.00 cP, and its pH was 1.88. Typical YBCO nanofibers were 50–100 nm in diameter and around of 10 μm length. The nanofibers also contain relatively small amounts of yttrium oxide and copper yttrium oxide.     

A water transport model for the creep response of the intervertebral disc

Time-dependence in the mechanical response of the intervertebral disc has previously been shown to arise from the transport of water out of the disc. A creep model has been devised which describes the water transport in terms of the disc structure. This model assumes that the flow of water is the result of a pressure gradient across the cartilage end-plates, caused by an externally applied stress. The fluid transport properties of the cartilage determine the flow rate. Several cases are studied; those that best fit the experimental results use either a straindependent or a time- and strain-dependent pressure gradient. The permeability of the disc system is in the range (0.20 to 0.85)×10^–17 m⁴N^–1 sec^–1 and depends on the stress level. These values are lower than those reported in the literature for articular cartilage, but this can be explained in part by the differences in water content of the cartilage types. Permeability is found to decrease with applied stress, and both the strain- and time-dependence parameters increase in magnitude with stress. It can be shown that the analytical models of the creep response of the disc are analogous to three- and four-parameter viscoelastic models that employ springs and dashpots.     

Dynamic 3-D computer graphics for designing a diagnostic tool for patients with schizophrenia

We introduce a novel procedure that uses dynamic 3-D computer graphics as a diagnostic tool for assessing disease severity in schizophrenia patients, based on their reduced influence of top-down cognitive processes in interpreting bottom-up sensory input. Our procedure uses the hollow-mask illusion, in which the concave side of the mask is misperceived as convex, because familiarity with convex faces dominates sensory cues signaling a concave mask. It is known that schizophrenia patients resist this illusion and their resistance increases with illness severity. Our method uses virtual masks rendered with two competing textures: (a) realistic features that enhance the illusion; (b) random-dot visual noise that reduces the illusion. We control the relative weights of the two textures to obtain psychometric functions for controls and patients and assess illness severity. The primary novelty is the use of a rotating mask that is easy to implement on a wide variety of portable devices and avoids the use of elaborate stereoscopic devices that have been used in the past. Thus our method, which can also be used to assess the efficacy of treatments, provides clinicians the advantage to bring the test to the patient’s own environment, instead of having to bring patients to the clinic.