Optical stimulation of neural tissue in vivo

For more than a century, the traditional method of stimulating neural activity has been based on electrical methods, and it remains the gold standard to date. We report a technological breakthrough in neural activation in which low-level, pulsed infrared laser light is used to elicit compound nerve and muscle potentials in mammalian peripheral nerve in vivo. Optically induced neural action potentials are spatially precise, artifact free, and damage free and are generated by use of energies well below tissue ablation threshold. Thus optical stimulation presents a simple yet novel approach to contact-free in vivo neural activation that has major implications for clinical neurosurgery, basic neurophysiology, and neuroscience.     

Real-time image linearization in a rotating prism-pair scanning system by using laser-diode encoding techniques

Rotating prism-pair scanning is a conventional method used to achieve large angles with a straight-line configuration. A disadvantage of prism scanners for line scanning is that the sinusoidal scan produces a non-linear image. We use a laser-diode encoding technique to carry out real-time image linearization in a rotating prism-pair scanning system. In this study, we report on the results obtained in a thermal image system.     

Solid-State Oxygen and Hydrogen Sensing Devices Based on Copper Dicyanoanthraquinone Diimines

Substituted dicyanoanthraqumone diimines (DCNAQI) and their related copper complexes, Cu(DCNAQI), have been synthesized and characterized. Most Cu(DCNAQI) complexes possess an activation energy 80–400 meV and strongly absorb in the IR range. Electrochemical investigations with polycrystailine electrodes as thin films reveal that Cu(DCNAQI) behaves as an n-type semiconductor. Under bandgap excitation (4000 cm^?1), the photoconductance measured with these Cu(DCNAQI) electrodes was greatly promoted under nitrogen, but very sensitive to O₂ or H₂. When the conductance difference, Δσ/σ_dark = (σ_light - σ _dark)σ _dark, was plotted vs the partial pressure of the target molecule, a nearly linear relationship was observed. Among Cu(DCNAQI), Cu(β-methyl-DCNAQI) gave the greatest senstivity for detection of hydrogen, but Cu(α,α′-dichloro-DCNAQI) appeared most sensitive toward oxygen. This remarkable relationship is likely due to retardation of the mobility of electron or hole by interaction with oxygen or hydrogen at the Cu(DCNAQI) electrode surface; a solid-state oxygen/hydrogen sensing device based on these organic semiconductors is proposed.     

Surface-plasmon-polariton dispersion of semiconductors with depletion layers

For a sample with plasma frequency varying exponentially from ω_ps at the surface to a larger value ω_pb in the bulk, and moderate damping, we find, contrary to other calculations, that the long wavelength surface plasmon dispersion has a single branch that is reentrant at ω = ω_ps.     

Regiospecific Syntheses of Sulfoxides and Sulfones of the (Z)-Configuration

A convenient synthesis for varions (Z)-1-alkanesulfinyl-2-phenylethenes has been developed. This involves addition of different sodium thiolates to phenylacetylene in ethanol, and oxidation of the resulting (Z)-1-alkanesulfenyl-2-phenylethenes [(Z)-styryl alkyl thioethers] with sodium metaperiodate supported on acidic alumina. The corresponding sulfones can be obtained by oxidation of these (Z)-styryl alkyl thioethers with hydrogen peroxide in glycial acetic acid, or, alternatively by reduction of the β-iodostyrylsulfones with zinc in acetic acid. These β-iodostyrylsulfones were obtained by addition of the corresponding sulfonyl iodides to phenylacetylene under the catalytic action of cupric chloride and triethylaminium chloride.     

Rheologie von konzentrierten kugelförmigen Suspensionen. I. Einwirkung der Grenzfläche flüssig-fest

Ohne Zusammenfassung     

Reentrant two-mirror ring resonator for generation of a single-frequency green laser

A nonplanar, reentrant two-spherical-mirror ring cavity is demonstrated. It is compact and free of astigmatism. Unidirectional operation is achieved by use of reciprocal and nonreciprocal polarization rotators to differentiate round-trip loss. A single-frequency green laser is generated by intracavity frequency doubling. Amplitude noise as low as 0.25% is achieved.     

Ferromagnetic resonance study of sputtered Co|Ni multilayers

We report on room temperature ferromagnetic resonance (FMR) studies of [ t Co|2t Ni]  × N sputtered films, where 0.1 ≤ t ≤ 0.6 nm. Two series of films were investigated: films with the same number of Co|Ni bilayer repeats (N = 12), and samples in which the overall magnetic layer thickness is kept constant at 3.6 nm (N = 1.2/t). The FMR measurements were conducted with a high frequency broadband coplanar waveguide up to 50 GHz using a flip-chip method. The resonance field and the full width at half maximum were measured as a function of frequency for the field in-plane and field normal to the plane, and as a function of angle to the plane for several frequencies. For both sets of films, we find evidence for the presence of first and second order anisotropy constants, K₁ and K₂. The anisotropy constants are strongly dependent on the thickness t, and to a lesser extent on the total thickness of the magnetic multilayer. The Landé g-factor increases with decreasing t and is practically independent of the multilayer thickness. The magnetic damping parameter α, estimated from the linear dependence of the linewidth ΔH, on frequency, in the field in-plane geometry, increases with decreasing t. This behaviour is attributed to an enhancement of spin-orbit interactions with decreasing Co layer thickness and in thinner films, to a spin-pumping contribution to the damping.     

Two-step sputtered ZnO piezoelectric films for film bulk acoustic resonators

This study investigates high-performance ZnO piezoelectric films used for thin film bulk acoustic resonators (TFBAR). The ZnO piezoelectric film was deposited on a Pt/Ti electrode using an RF magnetron sputter by a two-step method at room temperature. The Pt/Ti electrode was deposited by a DC sputtering system, on which, ZnO piezoelectric films were deposited in one step and in two steps to minimize roughness in the first step and produce the preferred orientation in the second. Both field-emission scanning electron microscopy (FESEM) and atom force microscopy (AFM) revealed that ZnO piezoelectric film deposited by two-step sputtering exhibited favorable characteristics, such as a rigidly precise surface structure with surface roughness of 7.37 nm, even better than in one-step sputtering. Examining the ZnO thin film by X-ray diffraction (XRD) showed a much higher c-axis-preferring orientation than in one-step sputtering. The reflection coefficient of the resonator device was measured using an HP8720 network analyzer. The frequency response of the FBAR device exhibited a return loss of -25 dB at a resonant frequency of 2212 MHz with a high coupling coefficient of 6.7%. PACS 68.55.Jk; 43.35.Ns; 81.15.-z     

Anisotropic power-law inflation of the five dimensional scalar–vector and scalar-Kalb–Ramond model

We will study the cosmological implications of the five dimensional scalar–vector and scalar-Kalb–Ramond model. In particular, a new set of Bianchi type I power-law analytic solution will be obtained for this model. The cosmic no-hair conjecture can be shown to break down in the presence of the scalar–vector and scalar-Kalb–Ramond couplings. The effect of the Kalb–Ramond field in the presence of the power-law solution will be shown explicitly. We will also show that the presence of a phantom field does, however, destabilize the corresponding Bianchi type I power-law inflationary solutions.