bluuebunny/crossref_metadata_2025 huggingface dataset:
Two-Dimensional Simulation of Quantum Tunneling across Barrier with Surface Roughness
Authors: Sakai Atsushi , Kamakura Yoshinari , Taniguchi Kenji
Published: December 2005

We present two-dimensional simulation of quantum tunneling across a potential barrier with surface roughness using quantum lattice–gas automata. The impact of the nonuniformity of the barrier thickness on the transmission coefficient is discussed by comparing the results of one- and two-dimensional tunneling simulations. The dependence of the transmission coefficient on the parallel momentum of the incident electron is also investigated, and it is demonstrated that the scattering by the surface roughness on the incident side of the interface causes the violation of the parallel momentum conservation. We discuss the effect of the obtained results on the gate current modeling for the scaled metal–oxide–semiconductor field-effect transistors.
Synchrotron Radiation Photoelectron Emission Study of SiO2 Film Formed by Hyperthermal O-Atom Beam at Room Temperature
Authors: Tagawa Masahito , Sogo Chie , Yokota Kumiko , Hachiue Syunsuke , Yoshigoe Akitaka , Teraoka Yuden
Published: December 2005

An ultrathin SiO2 overlayer on a Si(001) surface formed by a 5 eV O-atom beam at room temperature was analyzed by synchrotron radiation photoelectron spectroscopy (SR-PES). SR-PES spectra clearly indicated that the SiO2 layer formed by a hyperthermal O-atom beam at room temperature contains a small amount of suboxides compared with that formed by high-temperature oxidation in O2 atmosphere. Quantitative analysis suggests that the thickness of the structural transformation layer was less than a monolayer and the amount of suboxides was independent of the film thickness. The translational energy dependence of SR-PES spectra suggests that the reaction probability with a Si-atom increases with the translational energy of the O atoms in the range between 1 to 5 eV. The role of inverse diffusion of interstitial Si atoms in the kinetics of hyperthermal O-atom-beam oxidation is suggested.
Investigations of δ-Doped InAlAs/InGaAs/InP High-Electron-Mobility Transistors with Linearly Graded InxGa1-xAs Channel
Authors: Huang Jun-Chin , Hsu Wei-Chou , Lee Ching-Sung , Chen Yeong-Jia , Huang Dong-Hai , Chen Hsin-Hung
Published: December 2005

Comprehensive investigations of the various static and microwave performances of InAlAs/InGaAs/InP high-electron-mobility transistor (HEMT) with a linearly graded In
x
Ga1-x
As channel (LGC-HEMT) have been conducted. LGC-HEEMT was compared with the same HEMT having a conventional lattice-matched In0.53Ga0.47As channel (LM-HEMT). Improved carrier transport characteristics and confinement capability achieved by employing a linearly graded channel have contributed to a high extrinsic transconductance (g
m) of 319 mS/mm, a high unity-gain cutoff frequency ( f
t) of 37 GHz, and a maximum oscillation frequency ( f
max) of 51 GHz at 300 K for a gate length of 0.65 µm. The improved gate-voltage swing, turn-on and output power characteristics of LGC-HEMT have also been discussed.
Performance Degradation Induced by Fringing Field-Induced Barrier Lowering and Parasitic Charge in Double-Gate Metal–Oxide–Semiconductor Field-Effect Transistors with High-κ Dielectrics
Authors: Autran Jean-Luc , Munteanu Daniela , Houssa Michel , Castellani-Coulié Karine , Said Ahmed
Published: December 2005

The electrical behavior of a decananometer double-gate (DG) metal–oxide–semiconductor field-effect transistor (MOSFET) with high-permittivity (high-κ) and stacked-gate dielectrics has been investigated using two-dimensional (2D) quantum numerical simulation. We show that in spite of a quasi-ideal control of the channel by the gates in the double-gate structure, the device performances can be significantly degraded when using high-κ dielectrics due to two important electrostatic limitations of high-κ materials: i) the fringing field-induced barrier lowering effect (FIBL) and ii) the presence of discrete fixed charges in the gate stack. The FIBL compromises the performance of short-channel devices when simultaneously increasing the dielectric constant and its physical thickness, whereas the charges trapped in the high-κ layer induce 2D potential fluctuations in the structure and degrades the subthreshold behaviour of the drain current.
Defect Reduction Treatment for Plasma–Tetraethylorthosilicate–SiO2 by High-Pressure H2O Vapor Heat Treatment
Authors: Watakabe Hajime , Sameshima Toshiyuki , Strutz Thomas , Oitome Teruki , Kohno Atsushi
Published: December 2005

Improvements in the electrical and structural properties of tetraethylorthosilicate (TEOS) SiO2 films fabricated by plasma-enhanced chemical vapor deposition (PECVD) method were investigated using high-pressure H2O vapor heat treatment. The density of interface trap states was reduced from 3.3×1012 (initial) to 5.1×1010 cm-2 eV-1 by 1.3×106 Pa H2O vapor heat treatment at 260°C for 9 h. The density of fixed charges was also reduced from 6.1×1011 to 1.3×1011 cm-2. The full width at half-maximum (FWHM) of the optical absorption band corresponding to vibration of Si–O–Si bonding was reduced from 82.9 to 78.1 cm-1. Narrowing in FWHM of the Si 2p core level peak measured by X-ray photoelectron spectroscopy (XPS) was also observed. The reduction in the FWHM probably results from improvement of the Si–O bonding network.
Roles of Colloidal Silicon Dioxide Particles in Chemical Mechanical Polishing of Dielectric Silicon Dioxide
Authors: Choi Wonseop , Singh Rajiv K.
Published: December 2005

Chemical mechanical polishing (CMP) is carried out using slurry particles in contact with a wafer and a pad. The size and distribution of particles between the wafer and the pad play a crucial role in achieving desired CMP performance. Polishing rates and friction forces were measured as a function of particle size and solids loading, and surface finishes of silica wafers polished with colloidal silica particles were analyzed to validate the polishing mechanism. On the basis of polishing rate, friction force and surface finish, polishing occurring at the pad-particles-wafer interface was analyzed and an interfacial contact model was proposed. Understanding the polishing mechanism using colloidal particles makes it possible to achieve desired CMP performance.
Localized Oxidation of the Cu Surface after Chemical Mechanical Planarization Processing
Authors: Kodera Masako , Nishioka Yukiko , Shima Shohei , Fukunaga Akira , Tsujimura Manabu
Published: December 2005

After chemical mechanical planarization (CMP) processing of a Cu/low-k structure device, defects are often observed and some of them induce problems in manufacturing very large scale integrated circuit (VLSI) devices. As an example of defects, watermarks and protrusions on the Cu are detected. We found that the number of watermarks or protrusions is strongly affected by the cleaning conditions. The energy dispersive X-ray analysis (EDX) showed that these protrusions were composed of Cu and O. Moreover, atomic force microscopy (AFM) observations revealed that these protrusions grew during the storage time after the postcleaning. Electrochemical measurements also indicated that the protrusions were oxidized copper formed in the cleaning solutions due to the difference in corrosion current densities for various conditions of the Cu surface. Therefore, optimization of the post-CMP cleaning processing is a key issue for the reduction of defects such as protrusions.
Stress Analyses during Chemical Mechanical Planarization Processing with Cu/Porous Low-k Structures of LSI Devices
Authors: Kodera Masako , Fukuda Akira , Mochizuki Yoshihiro , Hiyama Hirokuni , Tokushige Katsuhiko , Fukunaga Akira , Tsujimura Manabu
Published: December 2005

Porous low-k materials are required for the construction of 45-nm-node LSI devices. However, the extremely low Young's modulus values of these materials result in the stress corrosion cracking (SCC) of the Cu interconnects during chemical mechanical planarization (CMP). We performed finite element method analyses of the stress at each step during the CMP. The results showed that the horizontal tensile stress was especially concentrated at the edges of the isolated fine wiring, and that higher tensile stresses appeared at the step of the barrier CMP. Moreover, the maximum values of the tensile stress increased with a decrease in Young's modulus in the low-k films. The cause of the horizontal tensile stress was the downward CMP pressure, which indented the low-k films. These results suggest that CMP with a lower downward pressure and an LSI structure with a Cu dummy pattern were effective for avoiding SCC.
The Effect of Cerium Precursor Agglomeration on the Synthesis of Ceria Particles and Its Influence on Shallow Trench Isolation Chemical Mechanical Polishing Performance
Authors: Kim Dae-Hyeong , Kim Sang-Kyun , Kang Hyun-Goo , Park Jea-Gun , Paik Ungyu
Published: December 2005

The level of agglomeration in the cerium precursor and its effect on the physicochemical properties of the synthesized ceria particles and how these properties influence shallow trench isolation chemical mechanical polishing (STI CMP) performance were investigated. Two different types of ceria particles were synthesized from cerium precursors of different degrees of agglomeration. The crystallinity and particle size distribution of the synthesized ceria particles were markedly different between these two types of particles. The ceria particles synthesized from agglomerated cerium precursors had a smaller crystallite size than the other particles due to the incomplete decarbonation reaction, which resulted in large agglomerations of particles. The different physical characteristics of the ceria particles resulted in remarkable discrepancies between the STI CMP performances of the ceria slurries, such as the oxide removal rate, the selectivity and the uniformity.
Tunable Terahertz Electromagnetic Wave Generation Using Birefringent Crystal and Grating Pair
Authors: Yano Ryuzi , Gotoh Hideki
Published: December 2005

We generated frequency-tunable terahertz (THz) waves with stable carrier-envelope phases (CEPs) by exciting a photoconductive antenna with intensity-modulated laser pulses. The modulation of a laser pulse by using a birefringent crystal and a grating pair produced two chirped laser pulses with a fixed time separation, or in other words, an intensity-modulated laser pulse. The stability of the CEP of the THz waves was governed by the stability of the time separation of the two laser pulses generated by the birefringent crystal. Because the crystal thickness was fixed, the CEP of the THz wave was stable and not affected by the mechanical vibration of the optical components. We also demonstrated the CEP control of the THz wave.
Effects of RF Power and Substrate Temperature during RF Magnetron Sputtering on Crystal Quality of ZnO Thin Films
Authors: Kim Choongmo , Kim Sookjoo , Lee Chongmu
Published: December 2005

The effects of rf power and substrate temperature on the crystal quality of ZnO thin films deposited on sapphire (001) substrates by rf magnetron sputtering are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and photoluminescence (PL) spectroscopy analyses. A ZnO thin film with the highest crystal quality is obtained by rf magnetron sputtering at a substrate temperature of 600°C and an rf power of 80 W. The crystal quality of the film is markedly improved by annealing. Excess rf power deteriorates the crystallinity and surface roughness of the film. PL spectroscopy analysis results confirm that rf magnetron sputtering yields ZnO films with a low density of crystallographic defects. Therefore, high-quality ZnO films can be obtained by optimizing the substrate temperature and rf power when using the rf magnetron sputtering technique and by annealing.
Compact Y-Branch-Type Polymeric Optical Waveguide Devices with Large-Core Connectable to Plastic Optical Fibers
Authors: Mizuno Hirotaka , Sugihara Okihiro , Kaino Toshikuni , Okamoto Naomichi , Ohama Motoshi
Published: December 2005

Y-branch-type polymeric optical waveguides with a large core size of 1000 µm, branching angles from 2 to 10° and a branching top-part radius of 200 µm were fabricated by hot embossing. An output power ratio of 1:1 from each output port and an excessive loss of ∼1.0 dB depending on branching angle were realized. A compact size Y-branch-type waveguide device with a wide branching angle was proposed.
Synthesis and Properties of [Bi0.5(Na1-xAgx)0.5]1-yBayTiO3 Piezoelectric Ceramics
Authors: Wu Lang , Xiao Ding-Quan , Lin Dun-Min , Zhu Jian-Guo , Yu Ping
Published: December 2005

A new group of ABO3-type lead-free piezoelectric ceramics, [Bi0.5(Na1-x
Ag
x
)0.5]1-y
Ba
y
TiO3, was developed, and the corresponding invention patent was submitted. The ceramics were synthesized by the conventional ceramic sintering technique using electronic grade raw materials, and the preparation techniques are very stable and convenient. The crystalline phase, microstructure and electric properties of the ceramics were also investigated. All the ceramics have high densities of about 5.70–5.84 g/cm3, which are more than 95% of the theoretical values. This system provides high piezoelectric performances: d
33=168 pC/N, k
p=0.31 when x=0.06, y=0.06. Moreover, the samples doped with a moderate amount of Mn could increase the mechanical quality factor Q
m and reduce the dielectric loss tgδ simultaneously. The temperature dependence of piezoelectric properties measured show that at up to 180°C, d
33 can still remain 126 pC/N for [Bi0.5(Na0.96Ag0.04)0.5]0.90Ba0.10TiO3 ceramics, which has a d
33 of 137 pC/N at room temperature.
Effect of Inner Electrode on Electrical Properties of (Zn,Mg)TiO3-Based Multilayer Ceramic Capacitor
Authors: Lee Wen-His , Su Chi-Yi , Huang Cheng-Liang , Lee Ying-Chieh , Hu Ching-Li , Yang Jackey , Yang Tong , Lin Shih-Pin
Published: December 2005

In this study, different proportions of silver–palladium alloy used as an inner electrode are adopted to fabricate (Zn,Mg)TiO3-based multilayer ceramic capacitors. Effects of sintering temperature, and measuring frequency on the dielectric properties of the samples with different proportions of the Pd–Ag inner electrode are investigated. The continuity of the inner electrode and the proportion of Pd–Ag of the inner electrode of samples sintered at different temperatures play important roles in determining the dielectric properties.
Temperature Dependence of Azimuthal Anchoring Strength of Liquid Crystals on Microgrooved Glass Substrate
Authors: Lin Yea-Feng , Lu Shin-Ying , Pan Ru-Pin
Published: December 2005

The temperature dependence of the azimuthal anchoring strength of the nematic liquid crystal (LC) 4'-n-pentyl-4-cyanobiphenyl (5CB) on parallel grooved glass substrates has been studied. The U-shaped grooves are prepared by reactive ion etching. Two parallel grooved substrates with chiral doped 5CB sandwiched in between are used to form an LC cell. The azimuthal anchoring strength in the nematic temperature range is determined by measuring the twist angle in the LC cells using an optical method at two laser wavelengths. The anchoring strength decreases steadily with increasing temperature. The change in the anchoring strength is attributed to the change in the elastic constant K
22 unless the temperature is close to the clearing point.
Formation of Yttrium Oxysulfide Phosphor at Room Temperature
Authors: Shoji Masahiko , Sakurai Kenji
Published: December 2005

Europium-doped yttrium oxysulfide (Y2O2S:Eu) phosphor was successfully synthesized at room temperature from yttrium oxide, europium oxide, and sulfur. The method employs high-energy ball milling to enable a substitution reaction between oxygen and sulfur, unlike conventional methods, such as heating in a sulfurizing atmosphere. It was found that the material is fluorescent through X-ray irradiation, and the luminescence spectra exhibit four peaks in the wavelength region from 500 to 800 nm.
Microstructure and Optical Properties of Ba0.65Sr0.35TiO3 Thin Films Prepared by RF Magnetron Sputtering
Authors: Zhang Tianjin , Li Songzhan , Zhang Baishun , Pan Ruikun , Jiang Juan , Huang Weihua
Published: December 2005

Ba0.65Sr0.35TiO3 thin films have been prepared by RF magnetron sputtering. The crystallization and microstructure of the films were characterized by X-ray diffraction (XRD), scan electronic microstructure (SEM) and atom force microstructure (AFM). As-deposited thin films were found to be amorphous. The more intense characteristic diffraction peaks and improved crystallization can be observed in (Ba,Sr)TiO3 (BST) thin films deposited at high temperatures and annealed at higher than 650°C. Optical constants were determined from transmittance spectra by using the envelope method. The refractive index increased from 1.778 to 1.961 as the substrate temperature increased from 560 to 650°C. Both the refractive index and extinction coefficient increased with annealing temperature. The refractive index and extinction coefficient increased when the oxygen-to-argon ratio increased from 1:4 to 1:1. The dispersion of relation of the extinction coefficient vs wavelength was also investigated. The optical band gap of BST thin films was found to be about 3.56 eV, which decreased apparently with increasing annealing temperature.
A Field-Emission Display with an Asymmetric Electrostatic-Quadrupole Lens Structure
Authors: Oh Tae Sik , Lee Jeong Hee , Lee Seong Eui , Min Kyoung Won , Kang Sung Kee , Yoo Ji Beom , Park Chong Yun , Kim Jong Min
Published: December 2005

An asymmetric electrostatic-quadrupole lens (AEQL) system for high definition field emission displays (HD-FEDs) was proposed. It was applied to the double-gated structure where the emitters are a thick layer of carbon nanotube paste such as a flat surface emitter. The AEQL structure was designed with two opposing planar electrodes of noncircular apertures which generate the quadrupole electric field. Utilizing a design of field emitter arrays (FEAs) with AEQL, an optimized beam shape with horizontal reduction and vertical elongation was obtained. According to three-dimensional (3D) simulation results, this AEQL structure exhibited excellent focusing effects that satisfied the aspects of pixel size and shape in HD-FEDs.
Measurements of Dose-Averaged Linear Energy Transfer Distributions in Water Using CR-39 Plastic Nuclear Track Detector for Therapeutic Carbon Ion Beams
Authors: Kohno Ryosuke , Yasuda Nakahiro , Takeshi Himukai , Kase Yuki , Ochiai Keiko , Komori Masataka , Matsufuji Naruhiro , Kanai Tatsuaki
Published: December 2005

A CR-39 plastic nuclear track detector was used as a linear energy transfer (LET) detector for carbon ion radiotherapy. We compared dose-averaged LET distributions in water obtained using the CR-39 detector for a monoenergetic beam and spread-out Bragg peak beam by calculations using the one-dimensional heavy-ion transport code used in the current heavy-ion treatment planning. We confirmed that the CR-39 detector could measure the high LET particles that are dominant contributors to dose-averaged LET. On the other hand, the CR-39 result was overestimated in the tail region of the distal edge in depth-dose distributions, due to its detection limit for lower LET particles. However, physical dose in the region is quite small. Namely, the effect of this difference on the biological dose distribution is also small. These results demonstrate that the CR-39 detector is a useful detector for measuring the LET distribution in carbon ion radiotherapy.
Microscopic Imaging of Phase Separation in Giant Liposome by Using Laurdan at Video Rate
Authors: Ohba Tetsuhiko , Tsuchiya Seigo , Kumeta Takaaki , Ohki Kazuo
Published: December 2005

Laurdan is a useful fluorescence dye for observation of physical properties of membranes. An optical system was constructed in order to image generalized polarization (GP), that characterizes the change of the spectrum of laurdan. The fluorescence images through the optical system were recorded on a digital video recorder and the images were processed to GP images, which made it possible to measure the spatial distribution of membrane fluidity quantitatively at video rate. Using this imaging instrument, the change of membrane fluidity at every moment of phase transition was observed in a giant liposome of pure dimyristoylphosphatidylcholine and the dynamics of phase separation was observed in a giant liposome composed of dimyristoylphosphatidylcholine and dimyristoylphosphatidylethanolamine after an annealing process. A clear phase separation was observed in the giant liposome in the cooling process from 43 to 40°C. The GP value of the phase-separated region on the liposome was related to the shape of the same region. The linear part of the liposome had a high GP value and the hinge part had a low GP value.
Testing thrust tectonic models at mountain fronts: where has the displacement gone?
Authors: Tozer R.S.J. , Butler R.W.H. , Chiappini M. , Corrado S. , Mazzoli S. , Speranza F.
Published: December 2005

The alternative relationships that can exist between a mountain front and the adjacent foreland basin have been recognized for many years. However, seismic reflection data from such areas are commonly of poor quality and therefore structural models may contain large uncertainties. In view of scientific and commercial interest in mountain belts, we have reviewed the methods for discriminating between alternative interpretations using a case study from the Montagna dei Fiori in the central Apennines, Italy. In this area Mesozoic and Tertiary carbonate sediments are juxtaposed with a foredeep basin containing up to 7 km of Messinian and Plio-Pleistocene siliciclastic sediments. A new structural model for this area demonstrates how the structures in this area form a kinematically closed system in which displacement is transferred from the thrust belt to blind structures beneath the present-day foreland. Growth strata show that Pliocene shortening was initially rapid (15 mm a
−1
) followed by slower rates during the final stages of deformation. Variations in structural elevation indicate a component of basement involvement during thrusting, and this is further supported by magnetic modelling. The results illustrate the interaction of thin- and thick-skinned structures in the central Apennines, and the methods for discriminating between alternative structural models.
Geochronology of Carboniferous–Permian magmatism in the Midland Valley of Scotland: implications for regional tectonomagmatic evolution and the numerical time scale
Authors: Monaghan Alison A. , Parrish R.R.
Published: December 2005

Four new U–Pb isotope dilution thermal ionization mass spectrometry dates from Carboniferous igneous rocks of the Midland Valley of Scotland are integrated with 16 recently published
40
Ar/
39
Ar dates. The numerical and stratigraphical ages of the dated samples are compatible to stage level, allowing improved intrabasinal and regional correlations. Early Carboniferous extension-related volcanism in the Midland Valley was pulsed, with a date of 343.4 ± 1.0 Ma from the Garleton Hills Volcanic Formation and dates of 334.7 ± 1.7 and 335.2 ± 0.8 Ma from the Clyde Plateau Volcanic Formation. The magmatic pulses are synchronous with synrift phases in the Northumberland–Solway Basin. Volcanism continued in mid- to Late Carboniferous time contemporaneous with dextral strike-slip tectonics, in contrast to a post-rift tectonic setting in northern England. After Late Carboniferous basin inversion, tholeiitic magmatism dated at 307.6 ± 4.8 Ma provides a maximum Westphalian D age for post-Variscan magmatism and extension–dextral transtension across Scotland and northern England. In the Early Permian, as rift systems developed across NW Europe, alkaline extension-related magmatism resumed in the Midland Valley from
c
. 298 to 292 Ma. The improved geochronology provides important data for poorly constrained parts of the numerical Carboniferous time scale such as stages within the Viséan, and provides a well-controlled tie-point that supports a Tournaisian–Viséan boundary age of
c
. 345.4 Ma.
Mesozoic extensional structures of the Fangshan tectonic dome and their subsequent reworking during collisional accretion of the North China Block
Authors: Yan Dan-Ping , Zhou Mei-Fu , Song Hong-Lin , Wang Gen-Hou , Sun Min
Published: December 2005

The Fangshan area, SW of Beijing, lies at the junction of the NNE-trending Taihang mountain range and the southeastern portion of the Yanshan intraplate orogenic belt and has undergone at least five stages of deformation. Mid- to late Triassic extensional deformation (D
1
) is represented by the formation of the Fangshan tectonic dome during SE-directed extensional tectonics. This deformation was later modified by NNW-directed thrusting in the late Triassic (D
2
) and WNW-directed thrusting in the late Jurassic (D
3
). These D
1
–D
3
structures were deformed by the arcuate Beiling syncline (D
4
), which formed during the intrusion of the 133–128 Ma Fangshan pluton. D
5
deformation is represented by Cretaceous to Quaternary NNE-striking high-angle normal faults. The ages of these events demonstrate that the principal ENE-trending tectonic framework of the Yanshan intraplate orogenic belt was established mainly in the mid- to late Triassic (the Indosinian event). The Jurassic to Cretaceous Yanshanian deformation with thick-skinned thrusting was associated with intrusion of numerous plutons, and strongly modified the older structures. The tectonic evolution of the Fangshan tectonic dome was linked genetically with the collision of the North China Block and the Siberian Craton, and the later collision of the North and South China blocks.
Sequence of tuffs between the KBS Tuff and the Chari Tuff in the Turkana Basin, Kenya and Ethiopia
Authors: Brown Francis H. , Haileab Bereket , McDougall Ian
Published: December 2005

This paper describes a sequence of tuffs between the KBS and the Chari Tuff of Omo Group formations in Kenya and Ethiopia. These tuffs have recently been shown to be 1.87 ± 0.02 Ma and 1.38 ± 0.03 Ma in age, respectively. The sequence of tuffs that is derived is consistent with
40
Ar/
39
Ar ages reported separately, and provides the stratigraphic framework for interpreting those ages. Further, new correlations are established to the Konso Formation in southern Ethiopia. As drainage from the Ethiopian Rift to the Omo–Turkana Basin developed after deposition of the Konso Formation, pumice clasts in tuffs of the Omo–Turkana Basin probably were transported there by the Omo River. The tuffs are divided into five groups on the basis of their stratigraphic position in relation to extensive ash layers. The sequence of tuffs has import for the placement and age of archaeological sites in the Koobi Fora Formation, and for ages of mammalian faunas (including hominids). Many tuffs were deposited during a 90 ka interval during which Mediterranean sapropels are lacking, suggesting that Nile flow was reduced, and that the level of a lake that occupied the Omo–Turkana Basin at the time was low. Thus the record of climatic influence on deposition in the Omo–Turkana Basin, previously shown for the Kibish Formation (≤200 ka), extends at least to early Pleistocene time.
Active deformation within the Zagros Mountains deduced from GPS measurements
Authors: Hessami Khaled , Nilforoushan Faramarz , Talbot Christopher J.
Published: December 2005

We present and interpret the results of Global Positioning System (GPS) measurements at 35 stations in and beside the Zagros Mountain belt, SW Iran, for three campaigns ending March 1998, December 1999 and June 2001. Preliminary motion estimates show clearly the change in character along the strike of the belt. Stations to the SE move at 13–22 ± 3 mm a
−1
towards N 7 ± 5°E with respect to Eurasia. Most of the shortening indicated by the GPS velocities seems to occur in the SE Zagros along two major seismic zones and along the Zagros front. To the NW, stations move oblique to the trend of the belt towards N 12 ± 8°W, at 14–19 ± 3 mm a
−1
. Most of the shortening in the NW Zagros seems to occur along the Mountain Front Fault with its major earthquakes as well as along the Zagros front. The change in direction and magnitude of the velocity vectors across the north–south-trending Kazerun and Karebas faults involves extension of up to 4 mm a
−1
along the strike of the Zagros belt.
The Current and Future Dynamics of Disease in Plant Communities
Authors: Burdon Jeremy J. , Thrall Peter H. , Ericson and Lars
Published: December 2005

Abstract  Pathogens are powerful evolutionary forces shaping the structure and dynamics of both individual species and of the communities of which they are part, at a broad range of genetic, ecological, spatial, and temporal scales. At all these levels their impact varies from the subtle and little recognized through to the most obvious destruction. Today the direct role of pathogens in natural plant communities is better recognized than at previous times, although the nuances of their interactions and the cascade of ramifications that can flow through changing biotic and abiotic effects are only now gaining recognition. However, as human influence on pathogens increases—either directly through enhanced if accidental dispersal, or through anthropogenic impacts on climate—we may expect to see increasing evidence of pathogens affecting plant species, community structure, and ecosystem function.
Fetal programming of hypertension
Authors: Alexander Barbara T.
Published: December 2005

Numerous epidemiological studies suggest an inverse relationship between low birth weight (LBW) and hypertension, an observation now supported by numerous animal studies. The mechanisms linking LBW and hypertension appear to be multifactorial and involve alterations in the normal regulatory systems and renal functions involved in the long-term control of arterial pressure. Recent studies using animal models of fetal programming suggest that programming during fetal life occurs in response to an adverse fetal environment and results in permanent adaptive responses that lead to structural and physiological alterations and the subsequent development of hypertension. This review summarizes the adaptive responses observed in the different models used to induce a suboptimal fetal environment and discusses insights into the mechanisms mediating the fetal programming of hypertension.
D5dopamine receptor regulation of reactive oxygen species production, NADPH oxidase, and blood pressure
Authors: Yang Zhiwei , Asico Laureano D. , Yu Peiying , Wang Zheng , Jones John E. , Escano Crisanto S. , Wang Xiaoyan , Quinn Mark T. , Sibley David R. , Romero Guillermo G. , Felder Robin A. , Jose Pedro A.
Published: December 2005

Activation of D1-like receptors (D1and/or D5) induces antioxidant responses; however, the mechanism(s) involved in their antioxidant actions are not known. We hypothesized that stimulation of the D5receptor inhibits NADPH oxidase activity, and thus the production of reactive oxygen species (ROS). We investigated this issue in D5receptor-deficient (D5−/−) and wild-type (D5+/+) mice. NADPH oxidase protein expression (gp91phox, p47phox, and Nox 4) and activity in kidney and brain, as well as plasma thiobarbituric acid-reactive substances (TBARS) were higher in D5−/− than in D5+/+ mice. Furthermore, apocynin, an NADPH oxidase inhibitor, normalized blood pressure, renal NADPH oxidase activity, and plasma TBARS in D5−/− mice. In HEK-293 cells that heterologously expressed human D5receptor, its agonist fenoldopam decreased NADPH oxidase activity, expression of one of its subunits (gp91phox), and ROS production. The inhibitory effect of the D5receptor activation on NADPH oxidase activity was independent of cAMP/PKA but was partially dependent on phospholipase D2. The ability of D5receptor stimulation to decrease ROS production may explain, in part, the antihypertensive action of D5receptor activation.
Manifestation of Mirror Syndrome after Fetoscopic Laser Photocoagulation in Severe Twin-Twin Transfusion Syndrome
Authors: Hayashi Satoshi , Sago Haruhiko , Hayashi Reiko , Nakagawa Satoshi , Kitagawa Michihiro , Miyasaka Katsuyuki , Chiba Toshio , Natori Michiya
Published: December 2005

Mirror syndrome is a preeclampsia-like disease first described in a case of severe hydrops fetalis caused by rhesus isoimmunization, later reported in some cases of nonimmunological fetal hydrops. Twin-twin transfusion syndrome (TTTS) is a severe complication associated with monochorionic pregnancies, in particular, severe TTTS with one hydropic fetus leading to a poor prognosis. We report here a case of mirror syndrome that occurred after selective fetoscopic laser photocoagulation in severe TTTS at 24 weeks’ gestation.
Survey of Smoking Attitudes in Grade School Children in Greece: A Preliminary Study
Authors: Lazuras Lambros , Rodafinos Angelos
Published: December 2005

Aims: Tobacco use among children and adolescents is a major public health concern. Past literature has indicated that smoking attitudes are reliable predictors of teen smoking. The present study explored the smoking attitudes of 4th–6th grade Greek pupils. Methods: Data were obtained from 379 Greek elementary school students who completed a smoking attitudes survey, based on the Bogalusa Heart Study. Findings and Conclusions: Analysis of variance indicated that 4th graders expressed significantly more positive attitudes towards tobacco use in three statements related to the psychological consequences of cigarette use, and to peer pressures to smoke. No gender differences were evident. Overall, pupils across grades expressed relatively negative attitudes towards smoking. Differences between school grades in certain statements denoting the psychological properties of tobacco use, and in peer pressures were attributed to 4th graders’ lack of knowledge in the particular areas.
Pulmonary Balloon Valvuloplasty in a Fetus with Critical Pulmonary Stenosis/Atresia with Intact Ventricular Septum and Heart Failure
Authors: Galindo A. , Gutiérrez-Larraya F. , Velasco J.M. , De la Fuente P.
Published: December 2005

Outcome of fetuses with critical pulmonary stenosis (critical PS) or atresia of the pulmonary valve (PA) with intact ventricular septum (IVS) is closely related with right ventricle hypoplasia and its consequent hemodynamics. Fetal echocardiography not only allows early detection of this condition but also monitors its normally unfavorable evolution. These cases may benefit from intrauterine intervention relieving outflow tract obstruction in order to achieve a biventricular circulation. Successful valvuloplasty of the pulmonary valve was performed in a fetus with critical PS-IVS and heart failure at 25 weeks. After the procedure there was a significant improvement in fetal hemodynamics. Follow-up scans at 34 weeks detected a significant restenosis with signs of circulatory failure leading to premature delivery of the baby. An immediate postnatal valvuloplasty successfully completed the ultimate objective of biventricular repair. Fetal pulmonary valvuloplasty is feasible and may change the natural history of the disease in fetuses with critical PS-IVS.
Impact of Three-Phase Bone Scintigraphy on the Diagnosis and Treatment of Complex Regional Pain Syndrome Type I or Reflex Sympathetic Dystrophy
Authors: Shehab Dia , Elgazzar Abdelhamid , Collier B. David , Naddaf Sleiman , Al-Jarallah Khalid , Omar Abdelmoneim , Al-Mutairy Moudi
Published: December 2005

Objective: To determine the impact of three-phase bone scintigraphy (TPBS) on the diagnosis and management of complex regional pain syndrome type I (CRPSI) or reflex sympathetic dystrophy (RSD). Subjects and Methods: Twentyconsecutive patients with a recent clinical evidence of CRPSI were referred for TPBS as part of their routine management plan. All patients underwent neurological examinations with special attention to the evaluation of clinical features of vasomotor, sudomotor, motor and sensory dysfunction. Patients were followed prospectively. When both the clinical and TPBS results supported the diagnosis of CRPSI, patients were started on treatment. Results: Of the 20 patients, TPBS supported the diagnosis of RSD in 9 who were treated with steroids and physiotherapy. Complete follow-up was available for 7 of them and all had a satisfactory response to treatment. For the remaining 11 patients RSD was diagnosed clinically but not confirmed by TPBS. On follow-up there was no evidence that TPBS failed to identify RSD in these 11 patients. Conclusion: The results indicate that TPBS confirmed the clinical diagnosis of RSD, and, more importantly, had a significant impact on its management.
Managing the Post-Myocardial Infarction Patient with Asymptomatic Left Ventricular Dysfunction
Authors: Philippides George J.
Published: December 2005

The percentage of post-myocardial infarction (MI) patients with asymptomatic left ventricular dysfunction (ALVD) is now estimated at 10%, and that number is expected to grow as reperfusion procedures increasingly become routine. Since average all-cause mortality risk in these patients is high (up to 27%), definitive diagnostics are recommended to screen all post-MI patients for ALVD, defined as left ventricular systolic dysfunction in the absence of heart failure symptoms. Post-MI management strategies for patients with ALVD target the two routes of progression to heart failure: (1) cardiac remodeling mediated by neurohormonal activation, and (2) continued and recurrent myocardial ischemic events. Clinical trials of neurohormonal antagonists in post-MI ALVD patients have shown that angiotensin-converting enzyme inhibitors attenuate left ventircular remodeling and that β-blocker therapy reverses remodeling for patients already on angiotensin-converting enzyme inhibitor therapy. Neurohormonal antagonist therapy is also associated with significant reductions in sudden death in post-MI ALVD patients.
Limitations of Commonly Used Internal Controls for Real-Time RT-PCR Analysis of Renal Epithelial-Mesenchymal Cell Transition
Authors: Elberg Gerard , Elberg Dorit , Logan Charlotte J. , Chen Lijuan , Turman Martin A.
Published: December 2005

Background/Aims: Progressive renal fibrotic disease is accompanied by the massive accumulation of myofibroblasts as defined by α smooth muscle actin (αSMA) expression. We quantitated gene expression using real-time RT-PCR analysis during conversion of primary cultured human renal tubular cells (RTC) to myofibroblasts after treatment with transforming growth factor-β1 (TGF-β1). We report herein the limitations of commonly used reference genes for mRNA quantitation. Methods: We determined the expression of αSMA and megakaryoblastic leukemia-1 (MKL1), a transcriptional regulator of αSMA, by quantitative real-time PCR using three common internal controls, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), cyclophilin A and 18S rRNA. Results: Expression of GAPDH mRNA and cyclophilin A mRNA, and to a lesser extent, 18S rRNA levels varied over time in culture and with exposure to TGF-β1. Thus, depending on which reference gene was used, TGF-β1 appeared to have different effects on expression of MKL1 and αSMA. Conclusions: RTC converting to myofibroblasts in primary culture is a valuable system to study renal fibrosis in humans. However, variability in expression of reference genes with TGF-β1 treatment illustrates the need to validate mRNA quantitation with multiple reference genes to provide accurate interpretation of fibrosis studies in the absence of a universal internal standard for mRNA expression.
Depression, Stress, and Quality of Life in Persons with Chronic Kidney Disease: The Heart and Soul Study
Authors: Odden Michelle C. , Whooley Mary A. , Shlipak Michael G.
Published: December 2005

Background: The effect of mild chronic kidney disease (CKD) on depression, stress, quality of life (QOL), and health status is not well understood. We compared these outcomes in subjects with and without CKD. Methods: We performed a cross-sectional study of 967 outpatients enrolled in the Heart and Soul Study. CKD was defined as a measured creatinine clearance <60 ml/min. Outcome measures included depressive symptoms measured using the Patient Health Questionnaire (PHQ), stress measured using the Perceived Stress Scale (PSS), and QOL and overall health rated as excellent, very good, good, fair, or poor. Results: The prevalence of depressive symptoms (17 vs. 19%, p = 0.4) or perceived stress (11 vs. 16%, p = 0.09) did not vary significantly by CKD. The prevalence of fair or poor QOL was not significantly different in subjects with CKD, compared with those without CKD (24 vs. 23%, p = 0.65). Age-adjusted analyses revealed a significant association of CKD with QOL (p = 0.003), however, this association no longer reached statistical significance after adjustment for confounders (p = 0.06). Subjects with CKD were more likely to report poor or fair overall health than subjects without CKD (42 vs. 34%, p = 0.03). After multivariate adjustment, CKD remained significantly associated with worse overall health (OR = 1.65, 95% CI 1.21–2.24, p = 0.001), and modestly associated with QOL (OR = 1.31, 95% CI 0.99–1.75, p = 0.06), but had no association with depression (p = 0.48) or stress (p = 0.24). Conclusion: In this study of persons with coronary artery disease, subjects with CKD had reduced overall health and modestly reduced QOL; however, mental health was similar in those with and without CKD. These findings suggest that self- assessed overall health may decline at earlier stages of renal dysfunction than mental health outcomes or QOL.
A Comparative Study of the Effects of Hemin and Bilirubin on Bilateral Renal Ischemia Reperfusion Injury
Authors: Demirogullari Billur , Ekingen Gülsen , Guz Galip , Bukan Neslihan , Erdem Ozlem , Ozen I. Onur , Memis Leyla , Sert Sevki
Published: December 2005

Background/Aims: The aim of this study was to determine the effects of hemin, a heme oxygenase-1 inducer, and bilirubin on renal ischemia-reperfusion (I-R) injury. Methods: 40 Wistar-Albino rats were allocated into six groups as follows: sham (S), bilirubin (B), hemin (H), ischemia/reperfusion (IR), IR + bilirubin (IRB) and IR + hemin (IRH). Conjugated bilirubin (20 mg·kg–1 i.v.) was given to rats in groups B and IRB, and hemin (50 mg·kg–1 i.p.) was given to rats in groups H and IRH just prior to reperfusion. Renal I-R was achieved by occluding the renal arteries bilaterally for 50 min. Following 6 h of reperfusion, blood was drawn to study BUN, creatinine and bilirubin, and tissue samples were harvested to determine the renal malonyldialdehyde and heme oxygenase-1 levels, and for histopathologic grading. Results: BUN, creatinine and malonyldialdehyde levels in group IRH were similar to controls whereas the results of groups IR and IRB were significantly higher (p < 0.01). There was a grade 2 damage in all I-R groups. Conclusion: This study showed the preventive effect of hemin on renal ischemia reperfusion injury. Administration of exogenous bilirubin did not prevent the I-R injury.
In vitro Susceptibility to Meropenem and Other Antimicrobial Agents among Gram-Negative Bacilli Isolated from Hospitalized Patients in Central India
Authors: Chitnis S. , Chitnis V. , Hemvani N. , Chitnis D.S.
Published: December 2005

Background: Growing multiple drug resistance among gram-negative bacilli among hospitalized patients is a serious therapeutic problem, and the aim of the study was to assess the situation in our hospital. Methods: Antimicrobial susceptibility testing with the disk method was carried out on 1,533 isolates of gram-negative bacilli from urine, pus, body fluid and blood from hospitalized patients. Results: Seventeen percent of isolates were susceptible only to meropenem and either to piperacillin + tazobactam, to cefoperazone + sulbactam or to both. Eleven percent of isolates were susceptible only to meropenem and 6% were resistant to all antimicrobial agents including meropenem. Conclusion: Growing multiple drug resistance among gram-negative bacilli in hospital practice demands a rigid antibiotic policy and strict infection control measures.
A novel in vitro model for the study of plaque development in atherosclerosis
Authors: Torzewski Michael , Dahm Manfred , Ochsenhirt Viola , Lehr Hans-Anton , Lackner Karl , Vahl Christian-Friedrich , Dorweiler Bernhard
Published: December 2005

For the study of atherogenesis in vitro, coculture systems have been devised, in which two or more cell types can be cultured in close contact to each other. Herein, we describe a novel in vitro model that aims at the simulation of the morphology ofa normal muscular artery allowing for the study of the initial events in atherosclerosis. Usinga modified fibrin gel as a scaffold for the coculture of endothelial cells (ECs) and smooth muscle cells (SMCs), we generated an autologous in vitro model with a multilayer growth of SMCs (intima-like structure) covered by an endothelium. The production of extracellular matrix (ECM) could be visualized histologically and verified by (i) ascorbic-acid dependent secretion of procollagenI into the supernatant and (ii) deposition of collagens I and III as well as laminin in the gel as assessed by immunohistochemistry. By BrdU-incorporation and Ki67 expression, the SMCs exhibited minimal proliferative activity, even when the culture period was extended to6 weeks. Lipoprotein insudation was investigated under simulated hypo-, normo-and hypercholesterolemic conditions through addition of 0.5, 1 or2 mg/mL LDL to the medium with subsequent time and dose dependend insudation of LDL. When human monocytes were added to the culture medium, infiltration and foam cell formation of macrophages and SMCs as well as expression of interleukin-8 (IL-8) was demonstrated. The in vitro model of the human vascular wall described herein appears to be suitable for the study of pivotal events in atherosclerotic plaque development. The applicability for long-term culture, the ability to study cell-matrix interactions and the opportunities for histomorphological and immunohistochemical examinations represent additional advantages of this model.
Stent-induced neutrophil activation is associated with an oxidative burst in the inflammatory process, leading to neointimal thickening
Authors: Kato Toru , Hikichi Yutaka , Hashimoto Shigemasa , Hirase Tetsuaki , Morooka Toshifumi , Imoto Yoshitaka , Takeda Yuji , Sendo Fujiro , Node Koichi , Inoue Teruo
Published: December 2005

Activation of leukocytes plays an essential role in the mechanism of restenosis. Prior research has focused on monocytes and little is known about the role of neutrophils in this process. Neutrophils are known to contribute to tissue injury through oxygen-derived free radicals that nitrate tyrosine. This study was designed to elucidate clinically the role of neutrophil-mediated oxidative burst in the regulation of the post-stent inflammatory process. In 36 patients undergoing coronary stenting, we serially measured serum levels of glycosyl-phosphatidil-inositol-anchored protein (GPI)-80, a modulator of Mac-1 on the surface of neutrophils, in samples of coronary sinus as well as peripheral blood. We also simultaneously measured the serum 3-nitrotyrosine/tyrosine ratio as an index of oxidative stress. The GPI-80 level and the 3-nitrotyrosine/tyrosine ratio increased in the coronary sinus after coronary stenting in a time-dependent manner; with the maximum increase of GPI-80 level (3.1±2.9 to 8.6±4.3 ng/ml, P<0.01) at 48 hours, and 3-nitrotyrosine/tyrosine ratio at 24 hrs (5.2±4.8 to 28.4±13.2 ×10−4, P<0.01), more strikingly than in the peripheral blood. In the coronary sinus blood, the 3-nitrotyrosine/tyrosine ratio was correlated with GPI-80 levels at 24 hr (R=0.58, P<0. 001) and at 48 hr (R=0.41, P<0.01). Multiple regressions analysis showed that the maximum responses of GPI-80 level and 3-nitrotyrosine/tyrosine ratio were independent predictors of angiographic late lumen loss. Our results may supporta hypothesis that Mac-1-dependent activation of neutrophils causes oxidative burst in the post-stent inflammatory process, possibly leading to restenosis.