bluuebunny/crossref_metadata_2025 huggingface dataset:
Oxygen Trap Hypothesis in Silicon Oxide
Authors: Kageshima Hiroyuki , Uematsu Masahi , Akiyama Toru , Ito Tomonori
Published: October 2006

A hypothesis on the atomic structure of silicon oxide is proposed to explain the discrepancy between theoretical and experimental studies on the oxygen diffusion and the interfacial reaction during the thermal silicon oxidation process. The hypothesis says that silicon oxide contains “oxygen traps”, in which the molecular oxygen can be located with almost 0 dissolving enthalpy. The density of the “traps” is ∼1016 cm-3. A possible local structure is also proposed based on the first-principles calculations.
The Dependence of Thermal-Cycling-Induced Failure Mechanism on Topological Feature of Passivated Metallic Conductors in Plastic-Encapsulated Microelectronic Devices
Authors: Lee Seong-Min
Published: October 2006

This work presents how thermal-cycling-induced cracking in a device pattern is influenced by manipulating the topological feature of passivated metallic conductors. The modification of the topological feature is done by the variation of the sidewall slope of metallic conductors. In order to compare thermal-cycling reliability in two kinds of devices with different surface morphologies, each device is prepared to have pre-existing cracks along its edge region. The propagation behavior of the cracks is then investigated for each device. Discontinuous but fast crack propagation is observed for the device with the poor topological feature (i.e., 70°-sidewall slope) during thermal-cycling from -65 to 150 °C. On the other hand, continuous but limited crack growth is detected for the device with the improved topological feature (i.e., 130°-sidewall slope). The reason why cracking behavior differs, depending on the different re-entrant angle of each device pattern, is explained by numerical calculation. Finite-element method (FEM) work shows that the concentration of shear stress at the re-entrant corner of the passivated metallic conductor with the steep sidewall slope is responsible for such discontinuous crack propagation. Therefore, if the topological feature of passivated metallic conductors is improved, the rapid propagation of the pre-existing crack such as sawing-induced damage into the active device pattern will be effectively prevented to ensure thermal-cycling reliability.
p-Substrate Partially Inverted Buried Heterostructure Distributed Feedback Laser Diode Performance Improvement by Inserting Zn Diffusion-Stopping Layer
Authors: Kadoiwa Kaoru , Ono Kenichi , Nishiguchi Harumi , Matsumoto Keisuke , Ohkura Yuji , Yagi Tetsuya
Published: October 2006

The leakage current mechanism of p-substrate partially inverted buried heterostructure (PPIBH) distributed feedback laser diode (DFB-LD) grown on a p-InP substrate was studied in equivalent circuit simulations and experiments. The results showed that the p-InP buffer layer, which adheres to the active layer, has an important role and increasing its carrier concentration reduces the leakage current. High doping in the buffer layer caused the LD characteristics to deteriorate, which was caused by Zn diffusion into the active layer from the substrate. To prevent this diffusion, an undoped InP as a Zn diffusion stopping layer inserted between the buffer layer and the substrate was proposed. The LD with this layer showed superior characteristics with a second intermodulation distortion of -50 dBc and an R
d of 2.9 Ω.
Diode-Pumped Passively Q-Switched Mode-Locked c-Cut Nd:GdVO4 Laser with Cr4+:YAG Saturable Absorber
Authors: Li Ming , Zhao Shengzhi , Yang Kejian , Li Guiqiu , Li Dechun , Wang Jing , An Jing
Published: October 2006

A diode-pumped passively Q-switched and mode-locked (QML) c-cut Nd:GdVO4 laser with Cr4+:YAG saturable absorber is realized in a V-type folded cavity. The mode-locked pulse inside the Q-switched pulse has a repetition rate of 143 MHz, and its average pulse width is estimated to be about 460 ps. About 90% modulation depth for the mode-locked pulses has been obtained. Basing on a hyperbolic secant function method, a developed rate equation model for Q-switched and mode-locked lasers was introduced, in which not only the Gaussian distribution of the intracavity photon density and the influences of the continuous pump rate were considered, but the stimulated radiation lifetime of the active medium as well as the excited-state lifetime of the saturable absorber were taken into account. The numerical solutions of the equations are in good agreement with the experimental results.
Reduction of Acoustic Waves Induced by Discharge in High Repetition Rate ArF Excimer Laser Cavity to Obtain Narrow-Bandwidth Laser Light
Authors: Kakizaki Koji , Yabu Takayuki , Hori Tsukasa , Mizoguchi Hakaru , Sakai Yosuke
Published: October 2006

The suppression of acoustic waves caused by discharge in a laser chamber, which is a technical challenge we face in the development of next-generation 6 kHz ArF lasers for lithography, is studied. In this paper, we describe, firstly, that the acoustic waves produced in an ArF laser medium were observed by a Schlieren method and analyzed by computer simulation. The simulation results successfully explained the gas density fluctuation pattern obtained in Schlieren photographs. On the basis of these results, the inner configuration of a laser chamber for 6-kHz-repetition-rate operation was newly designed. The new laser chamber provided narrow-bandwidth laser light up to a repetition rate of 6 kHz as a result of a marked suppression of acoustic waves.
Anomalous Reflection from Colloidal Crystals of Core–Shell Particles
Authors: Harada Masashi , Ishii Masahiko , Nakamura Hiroshi
Published: October 2006

The reflection from colloidal crystals of core–shell particles is evaluated by the calculation of photonic band structures, and is compared with the prediction of the Bragg condition. Although the results of the calculation of the photonic band structures are consistent with those of the Bragg condition, generally, the photonic band structures predict another reflection which has no origin in the Bragg condition, when the shell of the particle is sufficiently thin and the difference in refractive index between the core and the shell is relatively large. Moreover, no reflection is expected in the case of moderate shell thickness and moderate refractive index difference.
Two-Dimensional and Three-Dimensional Analysis of Taper Structures for Coupling into and out of Photonic Crystal Slab Waveguides
Authors: Chau Yuan-Fong , Sun Yuh-Sien , Tsai Din Ping
Published: October 2006

The appropriate technique for coupling light efficiently from the conventional silica waveguide (SWG) entrance and exit of a photonic crystal slab waveguide (PCSWG) in a square lattice of dielectric rods is determined by calculation using the two-dimensional (2D) and three-dimensional (3D) finite-difference time-domain method. Four types of taper structure as the interface between SWG and PCSWG have been investigated. Coupling efficiency is found to be highly sensitive to the taper structure, defect rod configuration, and slab thickness. We find that when the type D tapered structure with a pair of larger defect rods, which is more flexible during fabrication, is placed between input/output SWG and PCSWG, if alters the mode properties of the guide mode so that mode matching can be achieved by determining the optimum defect configurations. Also, detailed computations of the 2D device and 3D slab version are given.
Lifetime and Electric Characteristics of Encapsulated Organic Light-Emitting Devices
Authors: Yang Yong Suk , Chu Hye Yong , Lee Jeong-Ik , Park Sang-Hee Ko , Hwang Chi Sun , Chung Sung Mook , Do Lee-Mi , Kim Gi Heon , Ko Jun-Bin
Published: October 2006

Organic light-emitting devices (OLEDs) with tris-(8-hydroxyquinoline)aluminum (Alq3), which is typically a green emitter, have been studied by many researchers because of their potential for facilitating the development of flexible electronics. In this paper, the luminance characteristics, current, capacitance, and dispersion factor for degraded OLEDs, which were obtained by applying various bias currents (0.5≤I
Bias≤9 mA), are studied. The current dependences of lifetime were divided at approximately 2 mA, and they represented nearly linear behaviors but had different slopes in a logarithmic plot of lifetime versus ubias current. With OLEDs emitting, the anomaly of capacitance, as shown in the capacitance–voltage curve, occurred because of two factors, polarization in the bulk of organic materials and the interface between the metal and organic layers. In decayed OLEDs that had lower bias currents of less than 2 mA, it was found that the degradation of luminance was related to both the decrease in polarization and to the lowering of the injection barrier.
Laser Induced Modifications of Carbon Nanotube Composite Surfaces
Authors: Bassil A. , Puech P. , Bacsa W. , Pizani P. S. , Jasinevicius R. G. , Demont Ph. , Barrau S. , Lacabanne C. , Bacsa R. , Flahaut E.
Published: October 2006

Carbon nanotubes epoxy composites have been processed with high power laser pulses and micro-machined with a single crystal diamond tool. The effect of the dispersion of the carbon nanotubes (CNTs, 0.4 wt %) in the epoxy resin and carbon nanotube interaction with the composite matrix have been probed using spectroscopic Raman mapping. While the micro-machined surface maintains a good electrical conductivity after machining, the surface is poorly conductive after laser ablation. Laser processing (power 150 J/pulse, 1064 nm) transforms the surface of the carbon nanotube nanocomposite up to a distance of 25 µm. AFM images show that the diamond machined surface reduces the composite surface roughness.
Three-Dimensional Finite-Difference Time-Domain Simulation of Optical Absorption Properties of Al–N Films with Mesoscopic Surface Roughness
Authors: Ishiguro Takashi , Iijima Hirofumi
Published: October 2006

Incompletely nitrided sputtered aluminum (Al–N) films with mesoscopic surface roughness have a promising function of high solar absorptance [T. Ishiguro et al.: Jpn. J. Appl. Phys. 41 (2002) 292]. In this paper, we present an application by three-dimensional finite-difference time-domain (FDTD) method to the simulation of the optical properties of Al–N films. From the observed data, the optical and structural parameters of the specimen are determined. The simulation reproduces the systematic changes in the surface roughness dependences of absorptance and reflectance. The evaluated distribution of the local Poynting vector shows the refraction effect at the slope of protuberances on a rough surface. Additionally, energy absorption mainly takes place at the surface skin depth. As a result, it is confirmed that the FDTD method is useful for understanding local optical behavior in specimens with mesoscopic surface roughness.
Photoluminescence Characteristics of Sn-Doped, Molecular-Beam-Epitaxy-Grown ZnSe Crystal Layers
Authors: Kuronuma Ryouichi , Miyamoto Yoshinobu , Mita Yoh
Published: October 2006

A novel, distinct blue photoluminescence emission peaking at a 490 nm wavelength has been observed in Sn-doped, molecular-beam-epitaxy-grown ZnSe crystal layers at low temperatures, which bears characteristics analogous to those of the green emission previously reported in Pb-doped ZnSe crystal layers. The blue emission appears in Sn-doped crystal layers having good crystallographic quality and cannot be observed in the crystal layers with inferior quality. The blue emission shows a superlinear dependence on the excitation intensity. Discussions are presented on the nature of the blue emission due to Sn, particularly in conjunction with that of the green emission in Pb-doped ZnSe crystal layers.
Effects of Oxygen Vacancies on Relaxation Behavior of Mg-Doped BaTiO3
Authors: Cha Seon Ho , Han Young Ho
Published: October 2006

The effects of oxygen vacancy on the dielectric properties of Mg-doped BaTiO3 were studied as a function of frequency in the temperature range of 150–450 °C. In Ba(Ti1-x
Mg
x
)O3-x
, the Curie point (T
c) shifted to lower temperatures as the Mg content (x) was increased. Dielectric loss (tan
δ) peaks moved to higher frequencies with increasing Mg content (x) in the Ba(Ti1-x
Mg
x
)O3-x
system (0.0005≤x≤0.01) at 250 °C, whose peaks appeared at 0.5–6.9 kHz for x=0.0005–0.01. Loss (tan
δ) peaks also moved to higher frequencies with increasing temperature regardless of Mg content (x). The activation energy was estimated to be 0.46–0.53 eV at 150–300 °C and 1.08–1.12 eV at 350–450 °C. The activation energy at higher temperatures could be due to the extra energy required for the dissociation of the dipolar complex (Mg''Ti–VO
••) in addition to the dipolar motion of oxygen vacancies.
Dielectric Properties of BaTiO3 Thin Films Prepared by Laser Ablation
Authors: Fujita Junya , Suzuki Keigo , Wada Nobuyuki , Sakabe Yukio , Takeuchi Kazuo , Ohki Yoshimichi
Published: October 2006

To study the minimum particle size for a ferroelectric material at which ferroelectricity is retained, thin films composed of stoichiometric BaTiO3 nanoparticles were prepared by laser ablation of a Ba–Ti–O ceramic target using a differential mobility analyzer. Highly densified films of various uniform grain sizes were obtained after post-annealing at 600, 700, 800, and 900 °C in an oxygen atmosphere. The dielectric constants of the post-annealed films varied from 100 to 300, depending on the grain size from 65 to 136 nm. These values are comparable to those of BaTiO3 nano-granular films fabricated by metallorganic decomposition or the sol-crystal method. From the capacitance vs bias-voltage relationship and its hysteresis observed for the post-annealed films, it became clear that a phase transformation from paraelectric to ferroelectric occurs at a grain size of approximately 76 nm. It was also clarified from piezoresponse images of the post-annealed films obtained using a scanning probe microscope that ferroelectricity emerges in BaTiO3 nano-size grains at a grain size of approximately 55 nm.
Study on Birefringent Color Generation for a Reflective Ferroelectric Liquid Crystal Display
Authors: Valyukh Sergiy , Valyukh Iryna , Xu Peizhi , Chigrinov Vladimir
Published: October 2006

We study the possibility of a layer of a surface stabilized ferroelectric liquid crystal coupled with several retardation plates for birefringent color generation. Double and single polarizer reflective bistable dichromatic ferroelectric liquid crystal displays are considered. We demonstrate that one or two retardation plates are sufficient for a display having good color characteristics and high brightness. Optimal parameters for green/red and blue/yellow ferroelectric liquid crystal displays are found.
Characterization of Thick Amorphous Carbon Films Formed by Pulse Bias Filtered Cathodic Vacuum Arc
Authors: Yasui Nobuto , Inaba Hiroshi , Chiba Hiromu , Yang Xudong , Lau Shu Ping
Published: October 2006

To form several-micrometer-thick diamond-like carbon (DLC) films, pulse bias filtered cathodic vacuum arc deposition was performed. In this study, nonhydrogenated DLC films were evaluated using visible and ultraviolet Raman spectroscopy, an electron energy loss spectroscopy (EELS) and a nano indenter. All observations indicated that the sp3 ratio of the DLC films decreases with increasing applied pulse bias. However, a moderately high sp3 ratio of 42.3% was obtained for 500-nm-thick DLC films with a compressive stress of 3.5 GPa formed at a pulse bias of 500 V, a pulse width of 25 µs, and a frequency of 1500 Hz.
Effect of Low-Energy Ion Flux Irradiation on Synthesis of Superhard Nanocomposite Films
Authors: Li Zhuguo , Miyake Shoji , Wu Yixiong
Published: October 2006

Ti–Si–N films were deposited on the grounded Si(100) substrates by inductively coupled plasma (ICP)-assisted magnetron sputtering. The incident ion flux density at the substrate was varied by controlling the RF power. The effects of low-energy ion flux irradiation on the growth, microstructure and mechanical properties of the Ti–Si–N films have been investigated. An increase in ion flux density causes a transfer of the preferred orientation from TiN(111) to TiN(200). Under the conditions of high-density (∼2.0 mA/cm2) low-energy (∼20 eV) ion irradiation, low-stressed superhard nanocrystalline TiN/amorphous Si3N4 (nc-TiN/a-Si3N4) film was synthesized at the relatively low deposition temperature of 300 °C.
Numerical Simulation of High-Frequency Driven Dielectric Barrier Microdischarge with Coplanar Electrode Configuration in Ar
Authors: Otsuka Shin , Tochikubo Fumiyoshi , Uchida Satoshi
Published: October 2006

Two-dimensional numerical simulation based on the fluid model was carried out to investigate the fundamental property of high-frequency driven dielectric barrier microdischarge (DBMD) with a coplanar electrode configuration. For the simulation conditions, the gas is Ar at 100 Torr and the driving frequency of the applied voltage is 10 MHz. A gradual increase in electron density due to repeated electron avalanche in the rf electric field causes the gaseous breakdown of DBMD. The microdischarge structure such as the cathode sheath and arcuate bulk plasma is established after exceeding the electron density of 1013cm-3. The DBMD in the periodic steady-state is maintained by electron-impact ionization at the plasma-sheath boundary in front of the instantaneous cathode. The effects of gap length and electrode width on the DBMD characteristics are investigated. Gap length controls the gaseous breakdown voltage and electrode width controls discharge power and plasma density. We also showed that a high-frequency driven microplasma array provided a relatively uniform distribution of excited species.
Ratio of Transverse Diffusion Coefficient to Mobility of Electrons in High-Pressure Xenon and Xenon Doped with Hydrogen
Authors: Kobayashi Shingo , Hasebe Nobuyuki , Hosojima Takehiro , Ishizaki Takeshi , Iwamatsu Kazuhiro , Mimura Mitsuteru , Miyachi Takashi , Miyajima Mitsuhiro , Pushkin Kirill , Tezuka Chikara , Doke Tadayoshi , Kobayashi Masanori , Shibamura Eido , Ishizuka Akihiro
Published: October 2006

We have obtained the ratio of the transverse diffusion coefficient to the mobility of electrons multiplied by the elementary charge, in Xe and Xe+H2 under electric fields at a higher pressure of 1 MPa in comparison with those in preceding experiments. The results show that the density effect (nonlinear effect) of the ratio in both pure Xe and Xe+H2 is ≤15% below 1 MPa over the reduced electric field range from 0.08 to 0.6×10-17 V·cm2. We also found that the diffusion of an electron swarm is suppressed by adding trace amount of hydrogen to high-pressure xenon gas. We discuss the application of Xe+H2 gas to a new gamma-ray camera.
Reorganization of Redshifted Band in Merocyanine–Cd Arachidate Mixed Langmuir–Blodgett Films Induced by Hydrothermal Treatments
Authors: Mouri Syuji , Morita Shin-ichi , Miura Yasuhiro F. , Sugi Michio
Published: October 2006

The effect of hydrothermal treatments (HTT) on merocyanine (MS)–Cd arachidate mixed Langmuir–Blodgett (LB) films has been studied. At temperatures ranging from 30 to 90 °C, the redshifted J-band in the as-deposited state has been found to reorganize under the condition of 100% relative humidity, forming a new phase of further redshifted bands with spectra sharper than those of the as-deposited J-band. The HTT-induced phase closely resembles that induced by the heat treatment without humidity control, while the occurrence of the latter is limited to 60–70 °C. The water content introduced into the LB system during HTT is suggested to play a catalytic role in facilitating the reorganization by its lubricating and/or hydrolyzing effects to soften the film structure.
Development of Fiber-Coupled Compact Terahertz Time-Domain Spectroscopy Imaging Head
Authors: Inoue Ryotaro , Ohno Yasuhiro , Tonouchi Masayoshi
Published: October 2006

The development of a fiber-coupled compact terahertz time-domain spectroscopy (THz-TDS) imaging system is reported. We focus the THz waves by means of two silicon hyper-hemispherical lenses with no parabolic reflectors. The THz transmission image of an IC card clearly shows that the spatial resolution of the system is less than 0.75 mm, which is quantitatively consistent with the THz beam diameter at the focal point estimated by knife-edge measurement. The discrepancy between the effective frequency of THz broadband pulses and the frequency which gives the maximum dynamic range in the THz spectrum is considered to be due to the coherent high-frequency components of THz pulses.
Measurements and Characterization of Cerenkov Light in Fiber-Optic Radiation Sensor Irradiated by High-Energy Electron Beam
Authors: Lee Bongsoo , Cho Dong Hyun , Jang Kyoung Won , Chung Soon-Cheol , Lee Jeong-Whan , Kim Sin , Cho Hyosung
Published: October 2006

In general, Cerenkov light can cause a problem in detecting a real light signal that is generated in a fiber-optic radiation sensor using an organic scintillator for dose measurements of high-energy electron beams. In this study, the intensity of Cerenkov light is measured and characterized as functions of incident angles, energy, and field size of the electron beam from a LINAC (linear accelerator). To remove or minimize Cerenkov light, a subtraction method using a background optical fiber is investigated.
Electroosmotic Flow Driven by DC and AC Electric Fields in Curved Microchannels
Authors: Chen Jia-Kun , Luo Win-Jet , Yang Ruey-Jen
Published: October 2006

The purpose of this study is to investigate electroosmotic flows driven by externally applied DC and AC electric fields in curved microchannels. For the DC electric driving field, the velocity distribution and secondary flow patterns are investigated in microchannels with various curvature ratios. We use the Dean number to describe the curvature effect of the flow field in DC electric field. The result implies that the effect of curvatures and the strength of the secondary flows become get stronger when the curvature ratio of C/A (where C is the radius of curvature of the microchannel and A is the half-height of rectangular curved tube.) is smaller. For the AC electric field, the velocity distribution and secondary flow patterns are investigated for driving frequencies in the range of 2.0 kHz (Wo=0.71) to 11 kHz (Wo=1.66). The numerical results reveal that the velocity at the center of the microchannel becomes lower at higher frequencies of the AC electric field and the strength of the secondary flow decreases. When the applied frequency exceeds 3.0 kHz (Wo=0.87), vortices are no longer observed at the corners of the microchannel. Therefore, it can be concluded that the secondary flow induced at higher AC electric field frequencies has virtually no effect on the axial flow field in the microchannel.
In Situ High-Resolution Transmission Electron Microscopy of Elastic Deformation and Fracture of Nanometer-Sized Fullerene C60 Whiskers
Authors: Kato Ryoei , Asaka Koji , Miyazawa Kun'ichi , Kizuka Tokushi
Published: October 2006

We deformed crystalline whiskers composed of fullerene C60 molecules inside a high-resolution transmission electron microscope. The diameters of the whiskers ranged from 200 to 1000 nm and the length extended to the submillimeter scale. We selected one whisker with a body-centered tetragonal structure with a typical diameter, i.e., 540 nm, for analyses of deformation. It was found that the whisker arched elastically and the radius of curvature decreased to 20 µm until fracture, showing that the whisker's fracture strain was 0.013. Fracture occurred along {100} of the whisker, perpendicular to its longer growth axis.
Naturally occurring hypertension in New World nonhuman primates: potential role of the perifornical hypothalamus
Authors: Smith Orville A. , Astley Cliff A.
Published: October 2006

Hypertension is a prominent underlying factor in the genesis of cardiovascular-related morbidity and mortality. A major impediment to the investigation into the causes of the disease is the paucity of naturally occurring animal models of the disease. There is evidence that some species of New World primates spontaneously become hypertensive. We used chronically implanted pressure transducers to assess normally occurring blood pressure and heart rate levels at rest and during routine laboratory procedures in a group of one of these New World primates ( Aotus sp.). Resting mean arterial pressure ranged from 72 to 130 mmHg. Three animals were judged to have resting mean arterial pressure levels in the hypertensive range (≥110 mmHg). In all of the animals, pressor responses to routine laboratory events were exaggerated (average highest mean pressure during 1 min from any session was 97–196 mmHg). Subsequently, the region of the perifornical/lateral hypothalamus known to produce elevated blood pressure and heart rate responses to electrical stimulation was removed, and the blood pressure responses to the laboratory routines were significantly decreased and, in some cases, eliminated. Control lesions in nearby tissue had no effect on these responses. This region may play a critical role in initiating or exacerbating cardiovascular responses that contribute to the development of essential hypertension.
Effects of assuming constant optical scattering on measurements of muscle oxygenation by near-infrared spectroscopy during exercise
Authors: Ferreira Leonardo F. , Hueber Dennis M. , Barstow Thomas J.
Published: October 2006

The aim of this study was to examine the effects of assuming constant reduced scattering coefficient (μ[Formula: see text]) on the muscle oxygenation response to incremental exercise and its recovery kinetics. Fifteen subjects (age: 24 ± 5 yr) underwent incremental cycling exercise. Frequency domain near-infrared spectroscopy (NIRS) was used to estimate deoxyhemoglobin concentration {[deoxy(Hb+Mb)]} (where Mb is myoglobin), oxyhemoglobin concentration {[oxy(Hb+Mb)]}, total Hb concentration (Total[Hb+Mb]), and tissue O2 saturation (Sti[Formula: see text]), incorporating both continuous measurements of μ[Formula: see text] and assuming constant μ[Formula: see text]. When measuring μ[Formula: see text], we observed significant changes in NIRS variables at peak work rate Δ[deoxy(Hb+Mb)] (15.0 ± 7.8 μM), Δ[oxy(Hb+Mb)] (−4.8 ± 5.8 μM), ΔTotal[Hb+Mb] (10.9 ± 8.4 μM), and ΔSti[Formula: see text](−11.8 ± 4.1%). Assuming constant μ[Formula: see text] resulted in greater ( P < 0.01 vs. measured μ[Formula: see text]) changes in the NIRS variables at peak work rate, where Δ[deoxy(Hb+Mb)] = 24.5 ± 15.6 μM, Δ[oxy(Hb+Mb)] = −9.7 ± 8.2 μM, ΔTotal[Hb+Mb] = 14.8 ± 8.7 μM, and ΔSti[Formula: see text]= −18.7 ± 8.4%. Regarding the recovery kinetics, the large 95% confidence intervals (CI) for the difference between those determine measuring μ[Formula: see text] and assuming constant μ[Formula: see text] suggested poor agreement between methods. For the mean response time (MRT), which describes the overall kinetics, the 95% confidence intervals were MRT − [deoxy(Hb+Mb)] = 26.7 s; MRT − [oxy(Hb+Mb)] = 11.8 s, and MRT − Sti[Formula: see text]= 11.8 s. In conclusion, μ[Formula: see text] changed from light to peak exercise. Furthermore, assuming a constant μ[Formula: see text] led to an overestimation of the changes in NIRS variables during exercise and distortion of the recovery kinetics.
Inflammatory Response After Influenza Vaccination in Men With and Without Carotid Artery Disease
Authors: Carty Cara L. , Heagerty Patrick , Nakayama Karen , McClung E. Clair , Lewis Julieann , Lum Dawn , Boespflug Erin , McCloud-Gehring Carrie , Soleimani Behrooz R. , Ranchalis Jane , J. Bacus Tamara , E. Furlong Clement , Jarvik Gail P.
Published: October 2006

Objective—

Inflammatory markers are associated with vascular disease; however, variation in the acute phase response (APR) has not been evaluated. We evaluated whether the APR magnitude in men with severe carotid artery disease (CAAD) (>80% stenosis) differed from that of men without stenosis (<15% stenosis).

Methods and Results—

White males with (n=43) and without (n=61) severe CAAD receiving clinical influenza vaccinations were recruited. Their baseline and 24-hour after -vaccination blood samples were assayed for C-reactive protein (CRP), IL-6, and serum amyloid-a (SAA). In vivo APR to vaccination was measurable and varied among subjects. Adjusted for age, smoking, oral hypoglycemics, aspirin, and stain use, the relative 24-hour changes in levels of ln(CRP), ln(IL-6), and ln(SAA) were higher in men with CAAD than in men without, but only the SAA response was significant (
P
=0.02); the relative SAA response was 1.6 (95% confidence interval, 1.1 to 2.5) times higher in men with than without CAAD. The APR for all markers appeared to be independent of baseline levels.

Conclusions—

Influenza vaccination results in a mild, but measurable, APR in men with and without CAAD. SAA APR variability may be a predictor of severe vascular disease that is independent of basal SAA level.
Tissue Factor Pathway Inhibitor-2 Is Upregulated by Vascular Endothelial Growth Factor and Suppresses Growth Factor-Induced Proliferation of Endothelial Cells
Authors: Xu Zhenhua , Maiti Debasish , Kisiel Walter , Duh Elia J.
Published: October 2006

Objective—

The purpose of this study is to investigate the expression and regulation of type-2 tissue factor pathway inhibitor (TFPI-2) in endothelial cells, as well as the regulation of human endothelial cell (EC) function by TFPI-2.

Methods and Results—

Real-time polymerase chain reaction (PCR) and Western blot analysis revealed that vascular endothelial growth factor (VEGF) induced both time- and dose-dependent increase in TFPI-2 mRNA and protein expression in endothelial cells. TFPI-2 mRNA expression was also significantly upregulated by IL-1β, and modestly increased by both tumor necrosis factor (TNF)-α and fibroblast growth factor (FGF)-2, but not placental growth factor (PlGF). VEGF upregulation of TFPI-2 was dramatically reduced by inhibition of the MEK pathway. Administration of TFPI-2 protein suppressed both VEGF and FGF-2 stimulation of EC proliferation in a dose-dependent manner. A recombinant preparation of the first Kunitz-type domain of TFPI-2 (KD1) did not suppress growth factor stimulation of EC proliferation, suggesting a mechanism distinct from the proteinase inhibitory activity of TFPI-2. Exogenously added TFPI-2 protein suppressed VEGF-induced EC migration in 2 different assays. Recombinant wt-KD1 or the R24K mutant of KD1, but not the R24Q mutant, dramatically suppressed VEGF-induced EC migration. TFPI-2 protein, but not recombinant KD1, blocked VEGF-induced activation of both Akt and ERK1/2 in ECs. At higher doses, TFPI-2 protein blocked VEGFR2 activation.

Conclusion—

Our data suggest that VEGF-upregulation of TFPI-2 expression in endothelial cells may represent a mechanism for negative feedback regulation and modulation of its pro-angiogenic action on endothelial cells. TFPI-2, or derivatives of TFPI-2, may be novel therapeutics for treatment of angiogenic disease processes.
Cellular Mechanism Through Which Parathyroid Hormone–Related Protein Induces Proliferation in Arterial Smooth Muscle Cells
Authors: Fiaschi-Taesch Nathalie , Sicari Brian M. , Ubriani Kiran , Bigatel Todd , Takane Karen K. , Cozar-Castellano Irene , Bisello Alessandro , Law Brian , Stewart Andrew F.
Published: October 2006

Parathyroid hormone–related protein (PTHrP) is present in vascular smooth muscle (VSM), is markedly upregulated in response to arterial injury, is essential for normal VSM proliferation, and also markedly accentuates neointima formation following rat carotid angioplasty. PTHrP contains a nuclear localization signal (NLS) through which it enters the nucleus and leads to marked increases in retinoblastoma protein (pRb) phosphorylation and cell cycle progression. Our goal was to define key cell cycle molecules upstream of pRb that mediate cell cycle acceleration induced by PTHrP. The cyclin D/cdk-4,-6 system and its upstream regulators, the inhibitory kinases (INKs), are not appreciably influenced by PTHrP. In striking contrast, cyclin E/cdk-2 kinase activity is markedly increased by PTHrP, and this is a result of a specific, marked, PTHrP-induced proteasomal degradation of p27
kip1
. Adenoviral restoration of p27
kip1
fully reverses PTHrP-induced cell cycle progression, indicating that PTHrP mediates its cell cycle acceleration in VSM via p27
kip1
. In confirmation, adenoviral delivery of PTHrP to murine primary vascular smooth muscle cells (VSMCs) significantly decreases p27
kip1
expression and accelerates cell cycle progression. p27
kip1
is well known to be a central cell cycle regulatory molecule involved in both normal and pathological VSM proliferation and is a target of widely used drug-eluting stents. The current observations define a novel “PTHrP/p27
kip1
pathway” in the arterial wall and suggest that this pathway is important in normal arterial biology and a potential target for therapeutic manipulation of the arterial response to injury.
The Matricellular Protein CCN1 Is Essential for Cardiac Development
Authors: Mo Fan-E , Lau Lester F.
Published: October 2006

The matricellular protein CCN1 (formerly named CYR61) regulates cell adhesion, migration, proliferation, survival, and differentiation through binding to integrin receptors and heparan sulfate proteoglycans. Here we show that
Ccn1
-null mice are impaired in cardiac valvuloseptal morphogenesis, resulting in severe atrioventricular septal defects (AVSD). Remarkably, haploinsufficiency for
Ccn1
also results in delayed formation of the ventricular septum in the embryo and persistent ostium primum atrial septal defects (ASD) in ≈20% of adults. Mechanistically,
Ccn1
is not required for epithelial-to-mesenchymal transformation or cell proliferation and differentiation in the endocardial cushion tissue. However,
Ccn1
deficiency leads to precocious apoptosis in the atrial junction of the cushion tissue and impaired gelatinase activities in the muscular component of the interventricular septum at embryonic day 12.5, when fusion between the endocardial cushion tissue and the atrial and ventricular septa occurs, indicating that these defects may underlie the observed AVSD. Moreover, human
CCN1
maps to 1p21-p31, the chromosomal location of an AVSD susceptibility gene. Together, these results provide evidence that deficiency in matrix signaling can lead to autosomal dominant AVSD, identify
Ccn1
+/−
mice as a genetic model for ostium primum ASD, and implicate
CCN1
as a candidate gene for AVSD in humans.
Data Quality of the Meteo-France C-Band Polarimetric Radar
Authors: Gourley Jonathan J. , Tabary Pierre , Parent du Chatelet Jacques
Published: October 2006

The French operational radar network is being upgraded and expanded from 2002 to 2006 by Meteo-France in partnership with the French Ministry of the Environment. A detailed examination of the quality of the raw polarimetric variables is reported here. The analysis procedures determine the precision of the measurements and quantify errors resulting from miscalibration, near-radome interference, and noise effects. Correction methods to remove biases resulting from effective noise powers in the horizontal and vertical channels, radar miscalibration, and the system offset in differential propagation phase measurements are presented and evaluated. Filtering methods were also required in order to remove azimuthal dependencies discovered with fields of differential reflectivity and differential propagation phase. The developed data quality analysis procedures may be useful to the agencies that are in the process of upgrading their radar networks with dual-polarization capabilities.
B-cell extrinsic CR1/CR2 promotes natural antibody production and tolerance induction of anti-αGAL–producing B-1 cells
Authors: Shimizu Ichiro , Kawahara Toshiyasu , Haspot Fabienne , Bardwell Philip D. , Carroll Michael C. , Sykes Megan
Published: October 2006

B-1b cells produce IgM natural antibodies against α1-3Galβ1-4GlcNAc (αGal). These can be tolerized by nonmyeloablative induction of mixed chimerism using αGal-positive (αGal+) donor marrow. We assessed the role of CR1/2 in this model for induction of tolerance of B-1b cells. Mixed hematopoietic chimerism was induced in α1-3galactosyltransferase (GalT−/−) and GalT−/−Cr2−/− mice with αGal+ BALB/c marrow donors. Anti-αGal Ab and anti-αGal Ab–producing B cells became undetectable in GalT−/− chimeras, whereas they persisted in chimeric GalT−/−Cr2−/− mice. To determine whether CR1/2 expression on stromal cells and/or hematopoietic cells was critical for B-1–cell tolerance, we generated GalT−/− radiation chimeras in which CR1/CR2 was expressed on either stromal cells, hematopoietic cells, neither, or both. After induction of mixed chimerism from αGal+ allogeneic bone marrow (BM) donors, anti-αGal–producing B cells were rendered tolerant in reconstituted recipients expressing only stromal CR1/CR2. Our results suggest a possible role for follicular dendritic cells that pick up immune complexes via CR1/CR2 receptors in the tolerization of B-1b cells.
Skeleton-binding protein 1 functions at the parasitophorous vacuole membrane to traffic PfEMP1 to the Plasmodium falciparum–infected erythrocyte surface
Authors: Maier Alexander G. , Rug Melanie , O'Neill Matthew T. , Beeson James G. , Marti Matthias , Reeder John , Cowman Alan F.
Published: October 2006

A key feature of Plasmodium falciparum, the parasite causing the most severe form of malaria in humans, is its ability to export parasite molecules onto the surface of the erythrocyte. The major virulence factor and variant surface protein PfEMP1 (P falciparum erythrocyte membrane protein 1) acts as a ligand to adhere to endothelial receptors avoiding splenic clearance. Because the erythrocyte is devoid of protein transport machinery, the parasite provides infrastructure for trafficking across membranes it traverses. In this study, we show that the P falciparum skeleton-binding protein 1 (PfSBP1) is required for transport of PfEMP1 to the P falciparum–infected erythrocyte surface. We present evidence that PfSBP1 functions at the parasitophorous vacuole membrane to load PfEMP1 into Maurer clefts during formation of these structures. Furthermore, the major reactivity of antibodies from malaria-exposed multigravid women is directed toward PfEMP1 because this is abolished in the absence of PfSBP1.
The fission yeast DNA structure checkpoint protein Rad26ATRIP/LCD1/UVSD accumulates in the cytoplasm following microtubule destabilization
Authors: Baschal Erin E , Chen Kuan J , Elliott Lee G , Herring Matthew J , Verde Shawn C , Wolkow Tom D
Published: October 2006

Background

DNA structure checkpoints are conserved eukaryotic signal transduction pathways that help preserve genomic integrity. Upon detecting checkpoint signals such as stalled replication forks or double-stranded DNA breaks, these pathways coordinate appropriate stress responses. Members of the PI-3 kinase related kinase (PIKK) family are essential elements of DNA structure checkpoints. In fission yeast, the Rad3 PIKK and its regulatory subunit Rad26 coordinate the detection of checkpoint signals with pathway outputs.

Results

We found that untreatedrad26Δcells were defective for two microtubule-dependent processes: chromosome segregation and morphogenesis. Interestingly, cytoplasmic accumulation of Rad26-GFP occurred following treatment with microtubule destabilizing drugs, but not during treatment with the genotoxic agent Phleomycin. Cytoplasmic accumulation of Rad26-GFP depended on Rad24, a 14-3-3 protein also required for DNA structure checkpoints and morphogenesis. Results of over expression and epistasis experiments confirm that Rad26 and Rad24 define a response to microtubule destabilizing conditions.

Conclusion

Two DNA structure checkpoint proteins with roles in morphogenesis define a response to microtubule destabilizing conditions.
Dog Y chromosomal DNA sequence: identification, sequencing and SNP discovery
Authors: Natanaelsson Christian , Oskarsson Mattias CR , Angleby Helen , Lundeberg Joakim , Kirkness Ewen , Savolainen Peter
Published: October 2006

Background

Population genetic studies of dogs have so far mainly been based on analysis of mitochondrial DNA, describing only the history of female dogs. To get a picture of the male history, as well as a second independent marker, there is a need for studies of biallelic Y-chromosome polymorphisms.

However, there are no biallelic polymorphisms reported, and only 3200 bp of non-repetitive dog Y-chromosome sequence deposited in GenBank, necessitating the identification of dog Y chromosome sequence and the search for polymorphisms therein. The genome has been only partially sequenced for one male dog, disallowing mapping of the sequence into specific chromosomes. However, by comparing the male genome sequence to the complete female dog genome sequence, candidate Y-chromosome sequence may be identified by exclusion.

Results

The male dog genome sequence was analysed by Blast search against the human genome to identify sequences with a best match to the human Y chromosome and to the female dog genome to identify those absent in the female genome. Candidate sequences were then tested for male specificity by PCR of five male and five female dogs.

32 sequences from the male genome, with a total length of 24 kbp, were identified as male specific, based on a match to the human Y chromosome, absence in the female dog genome and male specific PCR results. 14437 bp were then sequenced for 10 male dogs originating from Europe, Southwest Asia, Siberia, East Asia, Africa and America. Nine haplotypes were found, which were defined by 14 substitutions. The genetic distance between the haplotypes indicates that they originate from at least five wolf haplotypes. There was no obvious trend in the geographic distribution of the haplotypes.

Conclusion

We have identified 24159 bp of dog Y-chromosome sequence to be used for population genetic studies. We sequenced 14437 bp in a worldwide collection of dogs, identifying 14 SNPs for future SNP analyses, and giving a first description of the dog Y-chromosome phylogeny.
Oxygen limitation modulates pH regulation of catabolism and hydrogenases, multidrug transporters, and envelope composition in Escherichia coli K-12
Authors: Hayes Everett T , Wilks Jessica C , Sanfilippo Piero , Yohannes Elizabeth , Tate Daniel P , Jones Brian D , Radmacher Michael D , BonDurant Sandra S , Slonczewski Joan L
Published: October 2006

Background

In Escherichia coli, pH regulates genes for amino-acid and sugar catabolism, electron transport, oxidative stress, periplasmic and envelope proteins. Many pH-dependent genes are co-regulated by anaerobiosis, but the overall intersection of pH stress and oxygen limitation has not been investigated.

Results

The pH dependence of gene expression was analyzed in oxygen-limited cultures of E. coli K-12 strain W3110. E. coli K-12 strain W3110 was cultured in closed tubes containing LBK broth buffered at pH 5.7, pH 7.0, and pH 8.5. Affymetrix array hybridization revealed pH-dependent expression of 1,384 genes and 610 intergenic regions. A core group of 251 genes showed pH responses similar to those in a previous study of cultures grown with aeration. The highly acid-induced gene yagU was shown to be required for extreme-acid resistance (survival at pH 2). Acid also up-regulated fimbriae (fimAC), periplasmic chaperones (hdeAB), cyclopropane fatty acid synthase (cfa), and the "constitutive" Na+/H+ antiporter (nhaB). Base up-regulated core genes for maltodextrin transport (lamB, mal), ATP synthase (atp), and DNA repair (recA, mutL). Other genes showed opposite pH responses with or without aeration, for example ETS components (cyo,nuo, sdh) and hydrogenases (hya, hyb, hyc, hyf, hyp). A hypF strain lacking all hydrogenase activity showed loss of extreme-acid resistance. Under oxygen limitation only, acid down-regulated ribosome synthesis (rpl,rpm, rps). Acid up-regulated the catabolism of sugar derivatives whose fermentation minimized acid production (gnd, gnt, srl), and also a cluster of 13 genes in the gadA region. Acid up-regulated drug transporters (mdtEF, mdtL), but down-regulated penicillin-binding proteins (dacACD, mreBC). Intergenic regions containing regulatory sRNAs were up-regulated by acid (ryeA, csrB, gadY, rybC).

Conclusion

pH regulates a core set of genes independently of oxygen, including yagU, fimbriae, periplasmic chaperones, and nhaB. Under oxygen limitation, however, pH regulation is reversed for genes encoding electron transport components and hydrogenases. Extreme-acid resistance requires yagU and hydrogenase production. Ribosome synthesis is down-regulated at low pH under oxygen limitation, possibly due to the restricted energy yield of catabolism. Under oxygen limitation, pH regulates metabolism and transport so as to maximize alternative catabolic options while minimizing acidification or alkalinization of the cytoplasm.
Trends in scientific activity addressing transmissible spongiform encephalopathies: a bibliometric study covering the period 1973–2002
Authors: Sanz-Casado Elías , Ramírez-de Santa Pau Margarita , Suárez-Balseiro Carlos A , Iribarren-Maestro Isabel , de Pedro-Cuesta Jesús
Published: October 2006

Background

The purpose of this study is to analyse the trends in scientific research on transmissible spongiform encephalopathies by applying bibliometric tools to the scientific literature published between 1973 and 2002.

Methods

The data for the study were obtained from Medline database, in order to determine the volume of scientific output in the above period, the countries involved, the type of document and the trends in the subject matters addressed. The period 1973–2002 was divided in three sub-periods.

Results

We observed a significant growth in scientific production. The percentage of increase is 871.7 from 1973 to 2002. This is more evident since 1991 and particularly in the 1996–2001 period. The countries found to have the highest output were the United States, the United Kingdom, Japan, France and Germany. The evolution in the subject matters was almost constant in the three sub-periods in which the study was divided. In the first and second sub-periods, the subject matters of greatest interest were more general, i.e Nervous system or Nervous system diseases, Creutzfeldt-Jakob disease, Scrapie, and Chemicals and Drugs, but in the last sub-period, some changes were observed because the Prion-related matters had the greatest presence.

Collaboration among authors is small from 1973 to 1992, but increases notably in the third sub-period, and also the number of authors and clusters formed. Some of the authors, like Gajdusek or Prusiner, appear in the whole period.

Conclusion

The study reveals a very high increase in scientific production. It is related also with the beginnings of research on bovine spongiform encephalopathy and variant Creutzfeldt-Jakob disease, with the establishment of progressive collaboration relationships and a reflection of public health concerns about this problem.