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91.
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93.
This research extends the study of temporal resolution of the tactual sensory system through measurements of temporal-onset order discrimination for continuous tonal signals addressing (a) the effects of frequency separation of the two stimuli whose onset orders are to be discriminated and (b) the effects of redundant coding of frequency and site of stimulation on performance. Sinusoidal signals were presented either at two separate digits (thumb and index finger of the left hand) or at a single site of stimulation (left index finger) using a multifinger tactual stimulation system. Measurements were obtained using a one-interval two-alternative forced choice procedure in which each interval consisted of the random-order presentation of two different stimuli with roving values of amplitude and duration. Thresholds were estimated from psychometric functions of d' as a function of stimulus-onset asynchrony (SOA). On average, temporal onset-order thresholds were larger for one-finger conditions (mean SOA of 74.8 ms) than for two-finger conditions (mean SOA of 48.5 ms) and decreased as frequency separation increased, particularly for single-site presentation. Redundant coding of frequency and site of stimulation resulted in higher resolution by a factor of 1.5 compared to frequency alone and by a factor of 1.2 compared to site alone. 相似文献
94.
Taylor TJ Burress CN Pandey L Gabbaï FP 《Dalton transactions (Cambridge, England : 2003)》2006,(39):4654-4656
Both pentafluorophenylmercury chloride and trimeric perfluoro-ortho-phenylene mercury interact with phenanthrene to form phosphorescent adducts which exhibit extended binary stacks in the solid state. 相似文献
95.
Carrer C Stolz M Lewitzki E Rittmeyer C Kolbesen BO Grell E 《Analytical and bioanalytical chemistry》2006,385(8):1409-1413
Thermodynamic and kinetic studies of metal binding to proteins require the investigation of metal-free proteins, which are
often difficult to obtain. We have developed a very fast and mild method to eliminate metal ions from proteins by column chromatography
using a commercially available Ni-NTA-type stationary phase. This material, initially designed for protein purification purposes
in biotechnology, acts as a strong cation chelator when Ni2+ ions are removed. We have tested this new method with Ca-ATPase, an integral membrane protein exhibiting a strong affinity
for Ca2+. By eluting the protein over the Ni2+-free NTA gel, we could remove 95% of the total Ca2+ and obtain an essentially Ca2+-free protein. This method is efficient with only a small amount of NTA gel, and we suggest that it can be applied in general
for removal of metal ions from proteins. Moreover, as this procedure can be carried out under mild conditions, the chosen
protein kept its enzymatic activity. 相似文献
96.
Fish C Green M Jeffery JC Kilby RJ Lynam JM McGrady JE Pantazis DA Russell CA Willans CE 《Chemical communications (Cambridge, England)》2006,(13):1375-1377
The cationic cages nido-[C2Bu(t)2P2E]+ (E = As, Sb), which are isolobal to the cyclopentadienyl cation, adopt square based pyramidal structures with the heavy pnictogen atom at the apex; NMR and computational methods have been used to probe the dynamic behaviour of the complexes. 相似文献
97.
We study symplectic surfaces in ruled symplectic 4-manifolds which are disjoint from a given symplectic section. As a consequence,
in any symplectic 4-manifold, two homologous symplectic surfaces which are C
0 close must be Hamiltonian isotopic. 相似文献
98.
Summary: Macromolecuar chemistry and polymer science have had an enormous impact in many areas of science, engineering, medicine and our daily life. It has not only changed our way of life forever, but also continuously to improve our living standard. Macromolecuar chemistry now also encompasses bioengineering, biomimetics, designer biological materials and nanobiotechnology. Here we summarize a few classes of short peptides that we discovered and invented with broad applications including 3D tissue cell culture, reparative and regenerative medicine, tissue engineering, slow drug release, stabilization of membrane proteins for develop nanobiotechnology and molecular devices. Molecular design using short peptides as new materials will play increasingly important role in biomedical research, nanobiotechnology, clinical science and medicine. 相似文献
99.
Seebauer EG Dev K Jung MY Vaidyanathan R Kwok CT Ager JW Haller EE Braatz RD 《Physical review letters》2006,97(5):055503
The technologically useful properties of a crystalline solid depend upon the concentration of defects it contains. Here we show that defect concentrations as deep as 0.5 microm within a semiconductor can be profoundly influenced by gas adsorption. Self-diffusion rates within silicon show that nitrogen atoms adsorbed at less than 1% of a monolayer lead to defect concentrations that vary controllably over several orders of magnitude. The results show that previous measurements of diffusion and defect thermodynamics in semiconductors may have suffered from neglect of adsorption effects. 相似文献
100.
Sharp interface material models can be related to phase field models by introducing an order parameter, whose value is assigned to the different phases of a material. The elastic material law is coupled to the evolution equation of the order parameter and cracking is addressed as a phase transition problem instead of a moving boundary value problem. A regularization parameter ϵ controls the width of the diffuse cracks represented by the order parameter and the underlying sharp interface model can be recovered from the phase field model by the limit ϵ → 0. However, in numerical simulations using standard finite elements with linear shape functions, the minimum value of ϵ is restricted by the grid size and therefore the discretization of the crack field requires extensive mesh refinement for small values of ϵ. In this work, we construct special 2d shape functions which take into account the exponential character of the crack field and its dependence on the parameter ϵ. Especially in simulations with small values of ϵ and a rather coarse mesh, the elements with exponential shape functions perform significantly better than standard linear elements. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献