Prefrontal white matter abnormalities in young adult with major depressive disorder: A diffusion tensor imaging study

Prefrontal impairments have been hypothesized to be most strongly associated with the cognitive and emotional dysfunction in depression. Recently, white matter microstructural abnormalities in prefrontal lobe have been reported in elderly patients with ma

Reduced swimming abilities in fast-growing transgenic common carp Cyprinus carpio associated with their morphological variations

Critical swimming speeds (U-crit) and morphological characters were compared between the F-4 generation of GH-transgenic common carp Cyprinus carpio and the non-transgenic controls. Transgenic fish displayed a mean absolute U-crit value 22.3% lower than the controls. Principal component analysis identified variations in body shape, with transgenic fish having significantly deeper head, longer caudal length of the dorsal region, longer standard length (L-S) and shallower body and caudal region, and shorter caudal length of the ventral region. Swimming speeds were related to the combination of deeper body and caudal region, longer caudal length of the ventral region, shallower head depth, shorter caudal length of dorsal region and L-S. These findings suggest that morphological variations which are poorly suited to produce maximum thrust and minimum drag in GH-transgenic C. carpio may be responsible for their lower swimming abilities in comparison with non-transgenic controls.

Fast-growing transgenic common carp mounfing compensatory growth

Compensatory growth is a phase of accelerated growth apparent when favourable conditions are restored after a period of growth depression. To investigate if F-2 common 'all-fish' growth hormone gene transgenic common carp (Cyprinus carpio) could mount compensatory growth, a 9 week study at 29 degrees C was performed. The control group was fed to satiation twice a day throughout the experiment. The other two groups were deprived of feed for 1 or 2 weeks, respectively, and then fed to satiation during the re-feeding period. At the end of the experiment, the live masses of fish in the deprived groups were still significantly lower than those of the controls. During the re-feeding period, size-adjusted mean specific growth rates and mean feed intakes were significantly higher in the deprived fish than in the controls, indicating a partial compensatory growth response in these fish. No significant differences were found in food conversion efficiency between the deprived and control fish during re-feeding, suggesting that hyperphagia was the mechanism responsible for increased growth rates. The proximate composition of the deprived fish at the end of the experiment was similar to that of the control fish. This study is, to our knowledge, the first to report that fast-growing transgenic fish can achieve partial compensation of growth following starvation. (c) 2007 The Authors Journal compilation (c) 2007 The Fisheries Society of the British Isles.

Application of fast Pade approximation in simulating photonic crystal nanocavities by FDTD technology

The exact calculation of mode quality factor Q is a key problem in the design of high-Q photonic crystal nanocavity. On the basis of further investigation on conventional Pade approximation, FDM and DFT, Pade approximation with Baker's algorithm is enhanced through introducing multiple frequency search and parabola interpolation. Though Pade approximation is a nonlinear signal processing method and only short time sequence is needed, we find the different length of sequence requirements for 2D and 3D FDTD, which is very important to obtain convergent and accurate results. By using the modified Pade approximation method and 3D FDTD, the 2D slab photonic crystal nanocavity is analyzed and high-Q multimode can be solved quickly instead of large range high-resolution scanning. Monitor position has also been investigated. These results are very helpful to the design of photonic crystal nanocavity devices. (C) 2008 Elsevier B.V. All rights reserved.

Photoluminescence study of AlGaInP/GaInP quantum well intermixing induced by zinc impurity diffusion

AlGaInP/GaInP quantum well intermixing phenomena induced by Zn impurity diffusion at 540 degrees C were studied using room-temperature photo luminescence (PL) spectroscopy. As the diffusion time increased from 40 to 120 min, PL blue shift taken on the AlGaInP/GaInP quantum well regions increased from 36.3 to 171.6 meV. Moreover, when the diffusion time was equal to or above 60 min, it was observed firstly that a PL red shift occurred with a PL blue shift on the samples. After detailed analysis, it was found that the red-shift PL spectra were measured on the Ga0.51In0.49P buffer layer of the samples, and the mechanism of the PL red shift and the PL blue shift were studied qualitatively. (C) 2007 Elsevier B.V. All rights reserved.

Compact non-binary fast adders using single-electron devices

This paper proposes compact adders that are based on non-binary redundant number systems and single-electron (SE) devices. The adders use the number of single electrons to represent discrete multiple-valued logic state and manipulate single electrons to perform arithmetic operations. These adders have fast speed and are referred as fast adders. We develop a family of SE transfer circuits based on MOSFET-based SE turnstile. The fast adder circuit can be easily designed by directly mapping the graphical counter tree diagram (CTD) representation of the addition algorithm to SE devices and circuits. We propose two design approaches to implement fast adders using SE transfer circuits the threshold approach and the periodic approach. The periodic approach uses the voltage-controlled single-electron transfer characteristics to efficiently achieve periodic arithmetic functions. We use HSPICE simulator to verify fast adders operations. The speeds of the proposed adders are fast. The numbers of transistors of the adders are much smaller than conventional approaches. The power dissipations are much lower than CMOS and multiple-valued current-mode fast adders. (C) 2009 Elsevier Ltd. All rights reserved.

Measuring spin diffusion of electrons in bulk n-GaAs using circularly dichromatic absorption difference spectroscopy of spin gratings

Circular dichromatic absorption difference spectroscopy is developed to measure the spin diffusion dynamics of electrons in bulk n-GaAs. This spectroscopy has higher detection sensitivity over homodyne detection of spin-grating-diffracted signal. A model to describe circular dichromatic absorption difference signal is derived and used to fit experimental signal to retrieve decaying rate of spin gratings. A spin diffusion constant of D-s=201 +/- 25 cm(2)/s for bulk n-GaAs has been measured at room temperature using this technique and is close to electron diffusion constant (D-c), which is much different from the case in GaAs quantum wells where D-s is markedly less than D-c.

Silicon-on-insulator thermo-optic variable attenuator module with fast response

A thermo-optic variable optical attenuator module composed of a silicon-on-insulator attenuator chip and driving circuit was designed and fabricated. The module exhibited a maximum attenuation of 21.8 dB and a response time of 10 mu s. (c) 2005 Society of Photo-Optical Instrumentation Engineers.

Rearrangeable nonblocking SOI waveguide thermooptic 4x4 switch matrix with low insertion loss and fast response

A rearrangeable nonblocking 4 x 4 thermooptic silicon-on-insulator waveguide switch matrix at 1.55-mu m integrated spot size converters is designed and fabricated for the first time. The insertion losses and polarization-dependent losses of the four channels are less than 10 and 0.8 dB, respectively. The extinction ratios are larger than 20 dB. The response times are 4.6 mu s for rising edge and 1.9 mu s for failing edge.

A silicon-on-insulator-based thermo-optic waveguide switch with low insertion loss and fast response

A silicon-on-insulator-based thermo-optic waveguide switch integrated with spot size converters is designed and fabricated by inductively coupled plasma reactive ion etching. The device shows good characteristics, including low, insertion loss of 8 +/- 1 dB for wavelength 1530-1580 nm and fast response times of 4.6 As for rising edge and 1.9 mu s for failing edge. The extinction ratios of the two channels are 19.1 and 18 dB, respectively.

Ferromagnetism in Mn and Cr doped GaN by thermal diffusion

Doping of magnetic element Mn and Cr in GaN was achieved by thermal diffusion. The conductivity of the samples, which were all n-type, did not change significantly after the diffusion doping. X-ray diffraction measurements revealed no secondary phase in the samples. Experiments using superconducting quantum interference device (SQUID) showed that the samples were ferromagnetic at 5 and 300 K, implying the Curie temperature to be around or over 300 K, despite their n-type conductivity. (c) 2004 Elsevier B.V. All rights reserved.

Fabrication and analysis of 2x2 thermo-optic SOI waveguide switch with low power consumption and fast response by anisotropy chemical etching

A low power consumption 2 x 2 thermo-optic switch with fast response was fabricated on silicon-on-insulator by anisotropy chemical etching. Blocking trenches were etched on both sides of the phase-shifting arms to shorten device length and reduce power consumption. Thin top cladding layer was grown to reduce power consumption and switching time. The device showed good characteristics, including a low switching power of 145 mW and a fast switching speed of 8 +/- 1 mus, respectively. Two-dimensional finite element method was applied to simulate temperature field in the phase-shifting arm instead of conventional one-dimensional method. According to the simulated result, a new two-dimensional index distribution of phase-shifting arm was determined. Consequently finite-difference beam propagation method was employed to simulate the light propagation in the switch, and calculate the power consumption as well as the switching speed. The experimental results were in good agreement with the theoretical estimations. (C) 2004 Elsevier B.V. All rights reserved.

Silicon-on-insulator-based waveguide switch with fast response

Based on thermo-optical effect of silicon, a 2 x 2 switch is fabricated in silicon-on-insulator by chemical etching. The switch presents an extinction ratio of 26 dB and a power consumption of 169 mW. The response time F similar to 10.5 mus.

A study on the minority carrier diffusion length in n-type GaN films

The minority carrier diffusion length of n-type GaN films grown by metalorganic chemical vapor deposition (MOCVD) has been studied by measuring the surface photovoltaic (PV) spectra. It was found that the minority carrier diffusion length of undoped n-type GaN is considerably larger than that in lightly Si-doped GaN. However, the data suggested that the dislocation and electron concentration appear not to be responsible for the minority carrier diffusion length. It is suggested that Si doping plays an important role in decreasing the minority carrier diffusion length.

As-doped p-type ZnO films by sputtering and thermal diffusion process

As-doped p-type ZnO films were grown on GaAs by sputtering and thermal diffusion process. Hall effect measurements showed that the as-grown films were of n-type conductivity and they were converted to p-type behavior after thermal annealing. Moreover, the hole concentration of As-doped p-type ZnO was very impressible to the oxygen ambient applied during the annealing process. In addition, the bonding state of As in the films was investigated by x-ray photoelectron spectroscopy. This study not only demonstrated an effective method for reliable and reproducible p-type ZnO fabrication but also helped to understand the doping mechanism of As-doped ZnO. (c) 2006 American Institute of Physics.