Changes in stuttering frequency as a function of various intervals of delayed auditory feedback.

5 different intervals of delayed auditory feedback (DAF) were presented to 6 severe stutterers while they read aloud. Results indicate that the continuous presentation of DAF significantly reduced stuttering frequency. Fluency enhancement was generally greatest during the shortest DAF intervals tested. No evidence was found for the carryover of fluency generated by DAF into the period immediately following Ss' experience on DAF. Results are consistent with a view that stuttering is based on a defect in the processing of auditory feedback. (15 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Exotic quantum effects in the laboratory?

This article provides a brief (non-exhaustive) review of some recent developments regarding the theoretical and possibly experimental study of 'exotic' quantum effects in the laboratory with special emphasis on cosmological particle creation, Hawking radiation and the Unruh effect.     

Caged capsaicins: New tools for the examination of TRPV1 channels in somatosensory neurons

The vanilloid capsaicin, N-(4-hydroxy-3-methoxybenzyl)-8-methylnon-6-enamide, is the pungent ingredient of chili peppers and is used in pain research as an activating ligand of heat-sensitive transduction channels in nociceptive neurons. Here we describe the synthesis and application of two capsaicin derivatives modified at the hydroxy function of the vanillyl motif: alpha-carboxy-4,5-dimethoxy-2-nitrobenzyl-caged (CDMNB-caged) capsaicin and {7-[bis(carboxymethyl)amino]coumarin-4-yl}methoxycarbonyl-caged (BCMACMOC-caged) capsaicin. These compounds show dramatically reduced pungency, but release active capsaicin upon irradiation with UV light. CDMNB-caged capsaicin can be used to perform concentration-jump experiments, while BCMACMOC-caged capsaicin is membrane-impermeant and can be applied selectively to the intracellular or extracellular sides of a plasma membrane. Both compounds can serve as valuable research tools in pain physiology.     

Spectral contrasts for landmark navigation

Visual robot navigation in outdoor environments would benefit from an illumination-independent representation of images. We explore how such a representation, comprising a black skyline of objects in front of a white sky, can be obtained from dual-channel spectral contrast measures. Light from sky and natural objects under different conditions of illumination was analyzed by five spectral channels: ultraviolet, blue, green, red, and near infrared. Linear discriminant analysis was applied to determine the optimal linear separation between sky and object points. A statistical comparison shows that contrasts with large differences in the wavelength of the two channels, specifically ultraviolet-infrared, blue-infrared, and ultraviolet-red, yield the best separation. Within a single channel, the best separation was obtained for ultraviolet light. The gain in separation quality when all five channels were included is relatively small.     

Role of optics in the accuracy of depth-from-defocus systems: comment

In their paper "Role of optics in the accuracy of depth-from-defocus systems" [J. Opt. Soc. Am. A24, 967 (2007)] the authors Blayvas, Kimmel, and Rivlin discuss the effect of optics on the depth reconstruction accuracy. To this end they applied an approach in Fourier space. An alternative derivation of their result in the spatial domain, based on geometrical optics, is presented and compared with their outcome. A better agreement with experimental data is achieved if some unclarities are refined.     

High-performance carbon nanotube field effect transistors with a thin gate dielectric based on a self-assembled monolayer

Individual single-walled carbon nanotube (SWCNT) field effect transistors (FETs) with a 2 nm thick silane-based organic self-assembled monolayer (SAM) gate dielectric have been manufactured. The FETs exhibit a unique combination of excellent device performance parameters. In particular, they operate with a gate-source voltage of only -1 V and exhibit good saturation, large transconductance, and small hysteresis (相似文献   

Amphiphilic conjugated block copolymers: synthesis and solvent-selective photoluminescence quenching

A novel, amphiphilic, conjugated block copolymer is described, which was prepared by a Suzuki-type cross-coupling of 2-bromo-[9,9-bis(2-ethylhexyl)fluorene]-7-pinacolato boronate as an AB-type monomer and monobromo-substituted poly[3-(6-bromohexyl)thiophene] (Br-P3BrHT) as a polymeric end capper in the key step. PF-P3PHT (P2; PF = poly(9,9-dialkylfluorene); P3PHT = poly[3-(6-diethylphosphonato-hexyl)thiophene]) as the amphiphilic target polymer was then generated in a polymer-analogous conversion of the alkyl bromide side chains of the PF-P3BrHT (P1) precursor into polar alkyl phosphonate groups by reaction with triethyl phosphite. P2 shows a strong influence of the solvent polarity on the optical spectra (absorption, emission). Treatment of solutions of P2 in tetrahydrofuran (THF), a nonselective solvent, with increasing amounts of solvents that are selective for the polar polythiophene blocks (water) or the nonpolar polyfluorene blocks (hexane), respectively, results in the formation of two different types of core-shell aggregates, which show rather different optical properties (photoluminescence quenching, excitation energy transfer).