4/spl times/10 GHz mode-locked multiple-wavelength fiber laser

We demonstrate a four-wavelength 10-GHz mode-locked erbium-doped fiber laser, with wavelength spacings of 3.5-5 nm. Nearly transform-limited Gaussian pulses of 11- to 14-ps duration are measured and all wavelengths are synchronous.     

Hyperbranched Polymers Containing Cyclopentadienyliron Complexes

A number of hyperbranched polymers containing cyclopentadienyliron moieties were prepared using the A₂+B₃ method. The A₂ compounds used were common diols, dithiols or dichloroarenecomplexes. B₃ compounds included either prepared star-shaped molecules or a purchased triol. The effect of the reaction conditions on the properties of the products was probed. Analysis of the prepared polymers was conducted using ¹H and ¹³C NMR, viscometry, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Viscometry values were generally found to be low, in the range of 0.175–0.300 dl/g. TGA showed losses starting at approximately 230°C and ending at 280°C, corresponding to the decomposition of the cyclopentadienyliron moiety. Degradation of the polyether backbone was found to occur starting at 390–567°C. Glass transition temperatures were found to be between 60 and 134°C, whereas melting temperatures ranged from 155 to 190°C.     

Estimation of yellow starthistle abundance through CASI-2 hyperspectral imagery using linear spectral mixture models

The invasive weed yellow starthistle (Centaurea solstitialis) has infested between 4 and 6 million hectares in California. It often forms dense infestations and rapidly depletes soil moisture, preventing the establishment of other species. Precise assessment of its canopy cover, especially low-density abundance in the earlier growing season, is the key to effective management. Compact Airborne Spectrographic Imager 2 (CASI-2) hyperspectral imagery was acquired at the western edge of California's Central Valley grasslands on July 15, 2003. Four linear spectral mixture models (LSMM) were investigated from the original CASI-2 data. Band selections based upon residual analysis and feature extraction (PCA) were further explored to reduce the data dimension. All approaches, except four band-selection unconstrained LSMMs, provide consistent results. The uncertainty of the PCA-based LSMM was estimated through a Monte-Carlo simulation. The maximum standard deviation was approximately 11%. The results suggest that unmixing CASI-2 imagery could be used for estimating and mapping yellow starthistle for larger regional areas.     

Process optimization for high electron mobility in nMOSFETs with aggressively scaled HfO/sub 2//metal stacks

The performance of aggressively scaled (1.4nm相似文献   

High-speed Ga0.47In0.53As/InP infra-redSchottky-barrier photodiodes

The authors report a new high-speed InP-based Ga_1-xIn _xAs infra-red Schottky-barrier photodiode. The photodiodes were fabricated on both p- and n-GaInAs epilayers using Schottky barrier height enhancement technology. The response speed was measured by the impulse response and autocorrelation method; the risetimes of 85 ps for p-GaInAs and 180 ps for n-GaInAs photodiodes were obtained, which correspond to the 3 dB cutoff frequency of 2-4 GHz. The intrinsic response speed was 12 GHz for n-GaInAs and 18 GHz for p-GaInAs photodiodes based on SPICE simulation with measured device parameters. The photodiodes had the responsivity as high as 0.55 A/W and the quantum efficiency of up to 45% at 1.3-1.6 μm without antireflection coating     

Isolation of Vibrio parahaemolyticus from fecal specimens on mannitol salt agar

Kittens of 25 and 50 days of age were tested on a passive avoidance task in a 2-compartment black-white shuttle box. Latency to enter the dark side of the box was the same for both groups on Day 1, but the latency to enter the dark side on Day 2 was much shorter for the younger kittens. Other kittens were trained in a step-up active avoidance task also at 25 and 50 days of age. No differences were found in active avoidance performance between the younger and older animals, indicating that active and passive avoidance tasks may possibly reflect separate developmental processes that mature at different rates in the cat.     

Reaction hot-pressing of zircon-alumina mixtures

Measurements have been made of the concurrent rates of reaction and of densification during the hot-pressing of mixtures of alumina and zircon powders. The results can be interpreted in terms of a liquid-phase sintering model and evidence is presented for separable stages of particle rearrangement, diffusion-controlled densification and residual reaction subsequent to attainment of zero porosity.