bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Growth Process on Structural and Optical Properties of Chemical Bath Deposition Cadimium Sulfide Thin Films
Authors: Li Xuguang , Li Wenyi , Dong Xiaobing
Published: December 2006

Hexagonal CdS thin films with a strong (002) orientation were successfully prepared by chemical bath deposition (CBD) using the reaction between CdCl2 and CS(NH2)2. A commonly available CBD system was successfully modified using a wetting agent (polyglycol) without agitation. Studies were performed to determine the effects of bath temperature on the properties of the films, such as optical transmission, surface morphology and the structure property. It was found that bath temperature plays a vital role in the quality of the CdS films. The increase in bath temperature improved the surface morphology of the CdS films and also decreased the number of pinholes on the films. The optimum bath temperature was 85 °C.
Structural, Dielectric, and Optical Properties of Ni-Doped Barium Cadmium Tantalate Ceramics
Authors: Liu Hongxue , Liu Shaojun , Zenou Victor Y. , Beach Cameron , Newman Nathan
Published: December 2006

We report the effect of Ni-doping on the structural, dielectric and optical properties of Ba(Cd1/3Ta2/3)O3 (BCT) ceramics. Rietveld analysis of the X-ray diffraction (XRD) data indicates that the BCT structure is similar to other Ba(B'1/3B''2/3)O3 perovskites, although the Ta–O–Cd is distorted to an angle of ∼173°; very close to our earlier theoretical prediction of 172°. The XRD analysis also indicates that Ni doping significantly enhances the extent of Cd–Ta ordering in BCT. The temperature coefficient of resonant frequency decreases with Ni concentration up to 2 wt %. While the loss tangent of BCT is reduced at small levels of Ni doping (up to 0.5 wt %), it increases abruptly at higher concentrations. We found a correlation between the loss tangent of Ni-doped BCT samples and the intensity of a continuous absorption background in the optical spectra. This optical activity results from the presence of optically active point defects and is suggestive that these defects play an important role in the microwave loss in BCT ceramics.
Fabrication of Twisted Nematic Gratings Using Polarization Hologram Based on Azo-Dye-Doped Liquid Crystals
Authors: Wu Shing-Trong , Chen Yi Shin , Guo Jian Hong , Fuh Andy Ying-Guey
Published: December 2006

This study establishes the feasibility of fabricating twist nematic gratings (TN-gratings) using a polarization holographic approach on the basis of the laser-induced adsorption of azo dyes by a polymer-coated glass substrate. This holographic recording is fast, and the formed TN gratings are permanent. Measurements indicate that the first-order diffracted-beam intensity from this TN grating is independent of the polarization of the incident beam. The polarization states of the zeroth- and first-order diffracted beams are perpendicular to each other. The polarization state and intensity distribution of the diffracted beams agree well with their theoretical values derived using the Jones matrix.
Shear Flow Orientation of Cylindrical Microdomain in Liquid Crystalline Diblock Copolymer and its Potentiality as Anchoring Substrate for Nematic Mesogens
Authors: Tokita Masatoshi , Adachi Mitsu-aki , Takazawa Fumihiro , Watanabe Junji
Published: December 2006

We prepared a diblock copolymer composed of polystyrene (PS) and side-chain liquid crystal polymer (LCP) by atom transfer radical polymerization. The weight fraction of the PS segment is 0.22, resulting in a microsegregated structure with PS cylinders hexagonally packed in a matrix of LCP, which forms smectic A, nematic and isotropic phases in order of increasing temperature. Shear flow at nematic temperatures orients well the PS microcylinders, as well as the nematic mesogens of the LCP in the velocity direction. A high degree of orientation of 0.95 is attained for microcylinders while the orientational order parameter of the nematic LC is around 0.5. Interestingly, the nematic LC mesogens recover their initial orientation upon cooling after they have lost the orientational order in the isotropic melt. This spontaneous orientation shows that PS cylinders whose orientation is strongly sustained with a temperature variation acts as an anchoring substrate for the nematic mesogens.
Annihilation of Acceptor–Hydrogen Pairs in Si Crystals Due to Electron Irradiation
Authors: Suezawa Masashi , Kojima Ken-ichi , Kasuya Atsuo , Yonenaga Ichiro , Usami Noritaka
Published: December 2006

We observed the annihilation of boron–hydrogen (BH) pairs and gallium–hydrogen (GaH) pairs during electron irradiation of Si crystals. BH and GaH pairs were generated by annealing of specimens co-doped with B or Ga and H. They were then irradiated with 3 MV electrons at room temperature. Intensities of optical absorption peaks due to BH and GaH pairs were observed at about 7 K. BH pairs and GaH pairs were found to decrease in one stage and two stages, respectively, with the increase of irradiation dose. These decreases were interpreted to be due to interactions between those pairs and self-interstitials.
Effect of Electrodes on Force–Frequency Characteristics of Rotated Y-Cut Quartz Resonators
Authors: Jing Yun , Gong Xun , Chen Jin , Gong Guiqiu , Zhang De , Shang Xiaoli , Xiong Jun , Duan Jie
Published: December 2006

The change in the resonance frequency of the thickness-shear vibration of rotated Y-cut quartz resonators using various electrode materials was studied. We used a three-dimensional finite element method to calculate the strain distribution of a circular plate and the electrodes under a pair of diametrical forces so that the anisotropy of the blank can be accurately considered. The relationship between mass-loading and force–frequency (F– f) characteristics is obtained for several types of electrode material. The results show that, for some electrode materials, the change in the F– f coefficients induced by the initial strain field distribution in the electrode through the third-order elastic constants is significant, but for others, the variations are small. We also find that the change is proportional to the thickness of the electrode. Furthermore, different materials have different effects. For most metals, such as gold, silver, copper, aluminum and nickel, with the increase in thickness, the F– f coefficient increase. However, for chromium, the increase in thickness may result in a lower F– f coefficient.
Preferentially Oriented Cu[111] Layer Formed on Thin Nb Barrier on SiO2
Authors: Maniruzzaman Md. , Takeyama Mayumi B. , Sato Masaru , Hayasaka Yuichiro , Aoyagi Eiji , Noya Atsushi
Published: December 2006

The texture of preferentially oriented Cu[111] deposited on a thin Nb layer is characterized in a thin-film stacked structure of Cu/Nb/SiO2/Si in an attempt to prepare a Cu[111] seed layer of interconnects on an extremely thin diffusion barrier. The Cu[111] layer is obtained on Nb films of [110] orientation at various thicknesses; however, the mosaic spread of Cu[111] texture depends on the thickness of Nb film underneath. The full width at half maximum of the ω-rocking curve measurement is ∼3° for the Cu[111] layer on a 100-nm-thick Nb layer, which increases to ∼4 and ∼5° for that on 20- and 10-nm-thick Nb layers, respectively. Transmission electron microscopy reveals the 10-nm-thick Nb layer consisting of fine relatively mosaic-spread [110] grains, which is a result of the initial stage of the nucleation type growth of the Nb film in a columnar structure on SiO2. It is revealed that the Cu[111] texture of relatively good mosaicity in a columnar structure is obtained on an extremely thin Nb layer of 10 nm thickness.
Growth Behavior of Dy/Cr Multilayers during Molecular-Beam Epitaxy and Their Structures
Authors: Kamada Yasuhiro , Tanino Hitoshi , Kingetsu Toshiki , Yamamoto Masahiko
Published: December 2006

We studied the growth and structures of Dy/Cr multilayers on Cr buffer layers formed on MgO substrates using a molecular-beam epitaxy technique. Reflection high-energy electron diffraction and X-ray diffraction analyses reveal that the periodic structure can be formed for various combinations of Dy and Cr layer thicknesses. The first Dy layers grow epitaxially on the Cr buffer although they are not single crystals. However, the subsequent layers become amorphous or finely crystalline for smaller thicknesses and polycrystalline for larger ones. The causes for these results are briefly discussed.
Thermal Stability of Lanthanum Oxynitride Ultrathin Films Deposited on Silicon Substrates
Authors: Kawada Nobuhito , Ito Masahiko , Saito Yoji
Published: December 2006

We prepared lanthanum oxynitride films on p-type Si(100) substrates by electron beam evaporation. The films were deposited by evaporating lanthanum at a substrate temperature of 300 °C, and introducing oxygen and nitrogen radicals into a chamber. After the thermal annealing of the films at 600 °C for 30 min, the composition and depth profile of the films were investigated by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES), respectively. We found that lanthanum oxynitride films suppress Si diffusion from the substrate as compared with lanthanum oxide films.
X-ray Diffraction Study of Electric Field-Induced Metal–Insulator Transition of Vanadium Dioxide Film on Sapphire Substrate
Authors: Okimura Kunio , Sasakawa Yusuke , Nihei Yusuke
Published: December 2006

An X-ray diffraction study of the electric field-induced metal–insulator transition (MIT) of a vanadium dioxide (VO2) film on a sapphire (001) substrate, which exhibited MIT at a temperature of approximately around 68 °C with a three-order change in resistivity, was performed. A simple device fabricated using a VO2 film having aluminum electrodes as ohmic contacts with a gap separation of 1.0 mm showed current jump at an applied voltage of 48 V. The X-ray diffraction of an in situ electrically biased VO2 film in transition state showed a crystalline structure change from monoclinic VO2 to tetragonal VO2 when compliance current was higher than a certain value. We found that this macroscopic crystalline structure change is not induced by electric field in the case of the lowest compliance current, indicating the significance of the current for fast and durable operation of VO2-based devices.
High Efficiency Stacked Organic Light-Emitting Diodes Employing Li2O as a Connecting Layer
Authors: Kanno Hiroshi , Hamada Yuji , Nishimura Kazuki , Okumoto Kenji , Saito Nobuo , Ishida Hiroki , Takahashi Hisakazu , Shibata Kenichi , Mameno Kazunobu
Published: December 2006

We demonstrate the high-efficiency stacked organic light-emitting diodes (OLEDs) introducing new connecting layers. In the green stacked OLEDs, the external efficiencies increase proportionally to the number of the stacked units without suffering the decrease in power efficiency. The current, power and external efficiencies at 0.5 mA/cm2 of the stacked OLED with six stacked units (6-stacked OLED) have reached 235 cd/A, 46.6 lm/W, and 65.8%, respectively. Furthermore, we have applied the connecting layers to a white stacked OLED and fabricated an active-matrix full-color display with a low temperature polysilicon thin film transistor backplane. In the device, the current efficiency of the white 2-stacked OLED is enhanced by a factor of 2.2. The initial luminance drop is significantly suppressed for the white 2-stacked OLED compared to 1-stacked OLED. The proposed white stacked OLED technology can be applied to a full-color display for a practical use.
Novel Electron-Transporting Carbazolylphenylquinolines for Phosphorescent Organic Light-Emitting Diodes
Authors: Takahashi Atsushi , Endo Ayataka , Adachi Chihaya
Published: December 2006

We developed four types of novel electron-transporting carbazolylphenyl-quinoline (CQ) derivatives. The photophysical and thermal properties of these materials were studied. Moreover, these materials were applied for an electron-transport layer and for a host material in phosphorescent organic light-emitting diodes, and a high electroluminescence (EL) efficiency was obtained in these devices. With 2-(3-(3,6-diphenylcarbazole-9-yl)phenyl)lepidine (DPCLP) as a host and tris(2-phenylpyridine)iridium(III) [Ir(ppy)3] as a guest, the highest EL efficiency of ηext=11.2% was obtained.
White Light Emitting Electrophosphorescent Devices with Solution Processed Emission Layer
Authors: Lee Jeong-Ik , Chu Hye Yong , Yang Yong Suk , Do Lee-Mi , Chung Sung Mook , Park Sang-Hee Ko , Hwang Chi-Sun
Published: December 2006

White light emitting diodes with high efficiency and brightness have been fabricated using phosphorescent materials by spin coating an emission layer. The emission layer consisted of sky blue and orange light emitting materials based on iridium complexes, which were dissolved in toluene solvent with 4,4'-bis(carbazoyl-9-yl)biphenyl (CBP) as a host and polystyrene as a binder. The introduction of polystyrene binder resulted in not only good film forming properties but also better device performance than that of poly(vinyl carbazole) conventionally used as a host material. The device structure was ITO/PEDT:PSS/emission layer/BAlq/LiF/Al. The color of the devices varied according to the composition of light emitting materials and the device having the closest to white emission showed CIE coordinates of (0.33,0.39) with an external quantum efficiency and a current efficiency of 6.1% and 13 cd/A, respectively, at 100 cd/m2.
Short Term Frequency Stability Tests of Two Cryogenic Sapphire Oscillators
Authors: Watabe Ken-ichi , Hartnett John G. , Locke Clayton R. , Santarelli Giorgio , Yanagimachi Shinya , Shimazaki Takeshi , Ikegami Takeshi , Ohshima Shin-ichi
Published: December 2006

Ultra-high short-term frequency stability has been realized in microwave oscillators based on liquid helium cooled sapphire resonators which operate on the same Whispering Gallery mode. Two cryogenic sapphire oscillators were built to evaluate their stability at short averaging times. These oscillators exhibited a fractional frequency stability of 1.1×10-15 at an averaging time of 1 s, which is more than 100 times better than that of a hydrogen maser. For averaging times between 2 and 640 s the measured oscillator fractional frequency instability was below 10-15 with a minimum of 5.5×10-16 at an averaging time of 20 s. The noise floors of the control servos which contribute to the short-term frequency stability are also discussed.
Fabrication and Mechanical Characterization of Micro Electro Mechanical System Based Vertical Probe Tips for Micro Pad Measurements
Authors: Ryu Jaewook , Kim Jin-Hyuk , Chu Sung-il , Lee SeungHun , Moon Sung
Published: December 2006

As a result of new developments in semiconductor technology, the number of pads per unit area is increasing and pad arrays are becoming irregular. Therefore, there is an increased need for a versatile probe card to address these issues. We developed a vertical micro electro mechanical system (MEMS) probe tip that is usable in a small pad (approximately 100 µm) and a two-dimensional pad array. The main process used to produce the tip was wafer bonding, silicon etching by deep reactive ion etcher (RIE) and electro-plating. The material of the electro-plated probe tip was an Ni–Co alloy. To optimize the design of the vertical probe tip, we designed various models and measured them in a micro compression and tensile tester. The structural analyses of the probe tip were accomplished using finite element method (FEM) and compared with actual measurement values. In this study, we demonstrated the potential of the vertical probe tip applied to a small area with the over drive (O.D.) of 10–40 µm and the contact force of 1–8g
f.
Surface Treatment of Poly(tetrafluoroethylene) and Perfluoroethylene-propylene by Radiation Grafting
Authors: Ito Naoki , Mase Atsushi , Seko Noriaki , Tamada Masao , Sakata Eiji , Kogi Yuichiro
Published: December 2006

Poly(tetrafluoroethylene) (PTFE) and perfluoroethylene-propylene (PFEP) have many desirable properties for application to electronic devices, such as low dielectric constant and loss tangent. However, the weak adhesion of the polymer to various metals, associated with the chemical inertness of the fluorine resin surface, fails to satisfy many of the industry requirements. Surface treatment of PTFE and PFEP by radiation-induced graft polymerization was carried out to improve the adhesion. Peel adhesion strengths of 10.3 and 14.5 N/cm were attained for PTFE/Cu and PFEP/Cu, respectively by the treatment. In addition, the dielectric function of grafted PTFE and grafted PFEP remained almost unchanged after the graft polymerization.
Distinguishing Bulk-Diffusion from Surface-Desorption Limited Gas Release Processes
Authors: Avila Ricardo E.
Published: December 2006

The release of a gas limited by surface desorption, or by diffusion from the bulk of spherical pebbles is revisited. A method is proposed to identify the release limiting process, by comparing a partial temperature ramp, up to slightly beyond the release peak, followed by a rapid temperature drop, to a second, full release ramp. Comparing the release curve from the second ramp to that of the first one: i) the peak is unmoved in first order desorption kinetics, and moves to higher temperature in the other cases, ii) as compared to the Arrhenius analysis of the first curve, that of the second is, again, identical in first order kinetics, in second order desorption it maintains the slope but lowers the intercept at the reciprocal temperature origin, and it is inapplicable in bulk diffusion kinetics.
Characteristics of Highly Sensitive pH Sensors with Charge Accumulation Operation
Authors: Hizawa Takeshi , Sawada Kazuaki , Takao Hidekuni , Ishida Makoto
Published: December 2006

A charge-transfer-type pH sensor operated by charge accumulation was demonstrated, and it was confirmed that its pH sensitivity was 1130 mV/pH with five signal integration cycles. The most familiar pH sensor using a semiconductor is the ion-sensitive field effect transistor (ISFET). The sensitivity of our pH sensor was 20 times higher than that of the ISFET. The sensitivity of the ISFET, which is similar in structure to a metal–insulator–semiconductor (MIS) structure, is restricted by the Nernst equation (59 mV/pH at room temperature). The output signal from an ISFET disappears into its noise as pH variation becomes small. The charge-transfer-type pH sensor increases the pH output signal to integrate signals in the time domain that are noise-free. It is expected that with this sensor it is possible to measure small pH signal variations.
High Resolution Transmission Electron Microscopy of Structural Change in Carbon Particle Carrying Pt Clusters
Authors: Shintaku Masayuki , Suzuki Hitoshi , Kaito Chihiro
Published: December 2006

The structural alteration of carbon nanoparticles compared with carbon thin film by heating at 80 °C in air was demonstrated. Marked differences in the structural alteration of carbon nanoparticles compared with carbon thin film were elucidated by heating at 80 °C in air. It becomes evident that the carbon particles used as the substrate of fuel cell catalysts changed their structure within 1000 h. Graphitization due to heating was demonstrated using a fast Fourier transform (FFT) of the high-resolution image.
Growth of Vertically Aligned Carbon Nanotube Bundles using Atmospheric-Pressure Microplasma
Authors: Yoshiki Hiroyuki , Okada Takeru , Hirai Kazuhiko , Hatakeyama Rikizo
Published: December 2006

Vertically aligned bundles of multiwalled carbon nanotubes (MWNTs) were grown on the tip of a φ0.5 mm nickel wire using an atmospheric-pressure microplasma (APµP) generated by a RF-powered pipe electrode. A CH4 and H2 gas mixture was used for the source gas, and the nickel wire used as the substrate was negatively biased to heat it by ion bombardment. At a ratio of CH4:H2=1:35, a RF power of 6 W, a DC bias voltage of -100 V and a growth time of 2 min, the tip of the nickel wire was covered by bamboo-like MWNT bundles, whose diameter and length were about 600 nm and 2–3 µm, respectively. Each bundle consisted of about 1500 tubes with diameters of 10–25 nm. The growth temperature of the MWNT bundles was approximately 500 °C.
Single Anti-Reflection Coating Optimization with Different Polarizations for Hyper Numerical Aperture Immersion Lithography
Authors: Jung Mi-Rim , Kwak Eun-A , An Ilsin , Oh Hye-Keun
Published: December 2006

Immersion lithography uses a hyper-numerical aperture (NA) to make smaller patterns and this hyper-NA imaging needs serious consideration of polarization effects. Immersion lithography using a hyper-NA affects the selection and optimization of various resolution enhancement techniques. Increasing the NA means a higher substrate reflectivity owing to a higher incidence angle. Thus, reflectivity should be considered with polarization in immersion lithography. Reflectivity at the resist-substrate interface has been a concern in the fabrication of many devices. To control the critical dimensions and the swing curve, we usually use anti-reflection coating (ARC). Lithography has become increasingly dependent on ARC to reduce reflectivity. If ARC has optimum parameters such as refractive index and thickness, we can obtain reduced reflectivity through the destructive interference of light. We suggest that different polarization states require different thicknesses of ARC to control reflectivity. The consideration of reflectivity based on a hyper-NA is also investigated. Different polarization states in terms of different ARC thicknesses for controlling reflectivity are also studied. The fidelity of different patterns is valid with different polarization states for reflectivity reduction. The substrate and resist reflectivity affect the line width swing curve. Therefore, we studied the effects of reflectivity on immersion lithography.
Vibrational Analysis of Organic Molecules Encapsulated in Carbon Nanotubes by Tip-Enhanced Raman Spectroscopy
Authors: Saito Yuika , Yanagi Kazuhiro , Hayazawa Norihiko , Ishitobi Hidekazu , Ono Atsushi , Kataura Hiromichi , Kawata Satoshi
Published: December 2006

Tip-enhanced Raman spectroscopy revealed the nanoscale chemical properties of organic molecules encapsulated in single-wall carbon nanotubes (SWNTs). Our approach is based on an enhanced electric field near a laser-irradiated metal tip functioning as a Raman excitation source. The enhanced field can successfully act on encapsulated molecules through the walls of the SWNTs to extract molecular vibrational information. β-carotene, which exhibits several active Raman modes under visible light illumination, was used as the encapsulated molecule. Tip-enhanced Raman spectra measured at seven different positions on SWNT bundles showed that β-carotene molecules inside the tubes were not uniformly distributed. We also found that the filling rate and peak position of the radial breathing mode of the SWNTs are linearly correlated.
Sedimentary processes in the Wilkes Land margin: a record of the Cenozoic East Antarctic Ice Sheet evolution
Authors: Donda F. , Brancolini G. , O'Brien P.E. , De Santis L. , Escutia C.
Published: December 2006

Multichannel seismic data collected off Wilkes Land (East Antarctica) reveal four main units that represent distinct phases in the evolution of the Cenozoic depositional environment. A Cretaceous synrift succession is overlain by hemipelagic and distal terrigenous sequences deposited during Phase 1. Sediment ridges and debris-flow deposits mark the transition to Phase 2. Unit 3 records the maximum sediment input from the continent and is characterized by the predominance of turbidite deposits. During Phase 4 the sediment supply from the continental margin was reduced, and draping and filling were the dominant processes on the continental rise. Unit 4 also contains the deposits of sediment wave fields and asymmetric channel-levee systems. These four units are a response to the Cenozoic evolution of the East Antarctic Ice Sheet. During Phase 1, small ice caps were formed in the innermost continental areas. The ice volume increased under temperate glacial regimes during Phases 2 and 3, when large volumes of melt-water production led to high sediment discharge to the continental rise. Change to a polar regime occurred through Phase 4, when a thick prograding wedge developed on the continental shelf and slope and the sediment transport to the rise diminished, producing general starvation conditions.
Facies architecture of the Grès de Peïra Cava, SE France: landward stacking patterns in ponded turbiditic basins
Authors: AMY LAWRENCE A. , KNELLER BENJAMIN C. , McCAFFREY WILLIAM D.
Published: December 2006

Basins in which turbidity currents are completely or partially trapped are common in many tectonically active, deep-water settings. Field study of an Eocene–Oligocene turbiditic system in the Peïra Cava area, a sub-basin of the Alpine foreland in southeastern France, allows spatial characterization of a ponded basin fill on the basis of a correlation framework derived from measured outcrop sections and photomosaics. The basin-fill architecture comprises a sand-rich, proximal scour-and-fill facies and a downstream transition to mud-rich, basin-plain turbidite sheet facies. The proximal facies is interpreted to have formed directly downstream of a slope break, where currents were highly erosional during some periods and highly depositional during other periods, as a result of the interacting effects of turbulence enhancement and rapid deceleration. Both the proximal facies and the downstream transition to distal basin-plain facies occur in progressively landward positions at higher stratigraphic levels. The landward shift in depositional facies is likely to have resulted from the basin-floor aggradation and a landward migration of the slope break. This ‘back-stepping’ process may be expected to occur in many ponded turbiditic basins and to produce a similar type of sedimentary architecture.
Siliceous sublacustrine spring deposits around hydrothermal vents in Lake Taupo, New Zealand
Authors: JONES BRIAN , DE RONDE C.E.J. , RENAUT ROBIN W. , OWEN R.B.
Published: December 2006

Chimneys around hydrothermal vents at a depth of
c
. 140 m in the Horomatangi Reefs area in Lake Taupo, New Zealand, are composed of amorphous silica (opal-A) with lesser amounts of Mn-, Fe-, and Hg-rich precipitates. Detrital quartz and feldspar grains are found in the surrounding sediments. The associated biota includes fish, bacteria, sponges, crayfish, amphipods, copepods, ostracodes, annelids, and other unidentified organisms. Much of this biota, however, is not preserved in the opal-A deposits. Instead, the silicified biota includes filamentous microbes and diatoms, scattered coccoid microbes, fungal hyphae and spores, rare sponge spicules, and rare worm(?) tubes. The diatoms, coccoid microbes, and fungi were brought into the area with the detrital sediment. In ancient successions, distinction between sublacustrine, terrestrial, and some marine hot spring deposits may be difficult because the precipitates share many similarities. Distinction based on the biota is viable only if palaeoecological information can be inferred from accurately identified organisms. Unfortunately, silicification commonly disguises microbes and precludes their accurate identification. Diagenetic transformation of opal-A to its more stable polymorphs also destroys many original depositional fabrics and silicified microbes. Distinction between the different types of spring deposit may therefore depend on the interpretation of their overall sedimentological and stratigraphic setting.
Detrital zircon ages in Neoproterozoic to Ordovician siliciclastic rocks, northeastern Australia: implications for the tectonic history of the East Gondwana continental margin
Authors: FERGUSSON CHRISTOPHER L. , HENDERSON ROBERT A. , FANNING C.MARK , WITHNALL IAN W.
Published: December 2006

U–Pb detrital zircon ages in variably metamorphosed, dominantly fine-grained clastic successions are used in northeastern Australia to identify two major successions along the East Gondwana margin. The older succession is of probable Late Neoproterozoic age and is considered part of a passive margin associated with rifting at
c
. 600 Ma. Most detrital zircons have ages in the range 1000–1300 Ma and were probably derived from an extension of a Late Mesoproterozoic (1050–1200 Ma) orogenic belt from the central Australian Musgrave Complex located 1500 km to the west. No evidence has been found for 600–800 Ma rifting of a Rodinian supercontinent and therefore it is suggested that breakup must have occurred well outboard of the present Early Palaeozoic East Gondwana margin. The younger succession is of Early Palaeozoic age and contains the distinctive 500–600 Ma detrital zircon signature that is widespread in East Gondwana in addition to some samples with ages in the range 460–510 Ma consistent with local igneous sources. The younger succession is related to the active margin of Gondwana that developed on the former passive margin in a back-arc setting, and the source of 510–600 Ma zircons is considered to be a composite of rift-related and back-arc volcanic sources.
Cessation/reactivation of polygonal faulting and effects on fluid flow in the Vøring Basin, Norwegian Margin
Authors: GAY A. , BERNDT C.
Published: December 2006

Polygonal faults, mainly oriented N50, N110 and N170, are abundant in the upper part of the mud-dominated Kai Formation (upper Miocene–lower Pliocene) of the Vøring Basin. A second, less-developed tier of polygonal faults, oriented N20, N80 and N140, exists at the base of the overlying Naust Formation (upper Pliocene–Present). The faults abruptly terminate upward below a thick interval of debris flows. We propose a dynamic model in which: (1) the development of polygonal faults discontinues temporarily as a result of a change in regional sedimentation, leading to inactive polygonal faults; (2) rapid emplacement of debris flows in the late Pleistocene creates a new interval of polygonal faults in the lower part of the Naust Formation immediately beneath the debris flow and some faults penetrate into the underlying Kai Formation; (3) some polygonal faults within the Kai Formation are reactivated and propagated upward into the base of the Naust Formation. The high interconnectivity between faulted layers allows the fluids to reach shallower depths, forming well-expressed pipes and pockmarks on the sea floor. The model of cessation/reactivation of polygonal faults constrains the sealing capacity of sedimentary cover over the reservoirs and helps to reconstruct the fluid migration history through the sedimentary column.
Evolution of experimental thrust wedges accreted from along-strike tapered, silicone-floored multilayers
Authors: Storti F. , Soto Marín R. , Rossetti F. , Casas Sainz A.M.
Published: December 2006

The possible effect of pre-deformational, along-strike sedimentary tapers on the structural architecture of thrust wedges accreted above viscous materials has been commonly underestimated or neglected. We illustrate results of an experimental programme specifically designed to study the impact of this parameter on thrust wedge evolution using sandbox analogue modelling. Two series of experiments were performed: the first series was designed to investigate the sensitivity of wedge growth to the along-strike sedimentary taper variability; the second was designed to investigate the sensitivity of a growing along-strike tapered wedge to the convergence rate. Our experimental results indicate that even gentle pre-deformational along-strike thickness variations in foredeep clastic sequences overlying viscous materials, such as evaporites or overpressured shales, can produce dramatic changes in the first-order structural architecture and kinematic evolution of accreting thrust wedges.
Terrane analysis along a Neoproterozoic active margin of Gondwana: insights from U–Pb zircon geochronology
Authors: Strachan R.A. , Collins A.S. , Buchan C. , Nance R.D. , Murphy J.B. , D'Lemos R.S.
Published: December 2006

The tectonic affinities of terranes in accretionary orogens can be evaluated using geochronological techniques. U–Pb zircon data obtained from paragneisses of the Coedana Complex (Anglesey) and the Malverns Complex, southern Britain, indicate that they were deposited during the mid- to late Neoproterozoic and have a comparable Amazonian provenance. Metamorphism of the Coedana gneisses occurred at 666 ± 7 Ma, similar to the age of metamorphism in the Malverns Complex. Anglesey therefore probably evolved in proximity to the Avalonian basement of mainland southern Britain during the mid- to late Neoproterozoic and is not a ‘suspect terrane’ relative to the remainder of Avalonia.
Hierarchical Earth accretion and the Hadean Eon
Authors: Kramers Jan D.
Published: December 2006

Geochemical traces from the Hadean Eon and terrestrial siderophile and volatile element data are discussed in the light of the standard, or hierarchical, model of planetary accretion, which envisages growth of the planets by collisions of progressively larger protoplanets. Siderophile element depletion patterns can be explained by partial inheritance from early stages of the process, when metal cores resulted from melting in collisions of small planetesimals. The abundances and isotope data for hydrogen and nitrogen suggest a chondrite-type source rather than nebular gas, in accord with atmosphere loss in the high-temperature aftermath of the Moon-forming Giant Impact, after which late accretion replenished the atmosphere. Lead isotope patterns and anomalous
142
Nd/
144
Nd ratios in early Archaean metasediments and
176
Hf/
177
Hf ratios of 3.7–4.4 Ga old detrital zircons point to a vanished crust that persisted through much of the Hadean Eon. A working hypothesis is proposed that links these observations. Following the freezing of a magma ocean caused by the Giant Impact, the mantle would be gravitationally unstable and an overturn would occur, leading to the formation of a huge mafic crust. After the overturn the mantle could be stable and inactive for hundreds of million years.
Visual Object Recognition: Do We Know More Now Than We Did 20 Years Ago?
Authors: Peissig Jessie J. , Tarr Michael J.
Published: December 2006

Abstract  We review the progress made in the field of object recognition over the past two decades. Structural-description models, making their appearance in the early 1980s, inspired a wealth of empirical research. Moving to the 1990s, psychophysical evidence for view-based accounts of recognition challenged some of the fundamental assumptions of structural-description theories. The 1990s also saw increased interest in the neurophysiological study of high-level visual cortex, the results of which provide some constraints on how objects may be represented. By 2000, neuroimaging arose as a viable means for connecting neurons to behavior. One of the most striking fMRI results has been category selectivity, which provided further constraints for models of object recognition. Despite this progress, the field is still faced with the challenge of developing a comprehensive theory that integrates this ever-increasing body of results and explains how we perceive and recognize objects.
Regulation of anion exchanger Slc26a6 by protein kinase C
Authors: Hassan Hatim A. , Mentone SueAnn , Karniski Lawrence P. , Rajendran Vazhaikkurichi M. , Aronson Peter S.
Published: December 2006

SLC26A6 (CFEX, PAT1) is an anion exchanger expressed in several tissues including renal proximal tubule, pancreatic duct, small intestine, liver, stomach, and heart. It has recently been reported that PKC activation inhibits A6-mediated Cl/HCO3 exchange by disrupting binding of carbonic anhydrase to A6. However, A6 can operate in HCO3-independent exchange modes of physiological importance, as A6-mediated Cl/oxalate exchange plays important roles in proximal tubule NaCl reabsorption and intestinal oxalate secretion. We therefore examined whether PKC activation affects HCO3-independent exchange modes of Slc26a6 functionally expressed in Xenopus oocytes. We found that PKC activation inhibited Cl/formate exchange mediated by Slc26a6 but failed to inhibit the related anion exchanger pendrin (SLC26A4) under identical conditions. PKC activation inhibited Slc26a6-mediated Cl/formate exchange, Cl/oxalate exchange, and Cl/Cl exchange to a similar extent. The inhibitor sensitivity profile and the finding that PMA-induced inhibition was calcium independent suggested a potential role for PKC-δ. Indeed, the PKC-δ-selective inhibitor rottlerin significantly blocked PMA-induced inhibition of Slc26a6 activity. Localization of Slc26a6 by immunofluorescence microscopy demonstrated that exposure to PKC activation led to redistribution of Slc26a6 from the oocyte plasma membrane to the intracellular compartment immediately below it. We also observed that PMA decreased the pool of Slc26a6 available to surface biotinylation but had no effect on total Slc26a6 expression. The physiological significance of these findings was supported by the observation that PKC activation inhibited mouse duodenal oxalate secretion, an effect blocked by rottlerin. We conclude that multiple modes of anion exchange mediated by Slc26a6 are negatively regulated by PKC-δ activation.
Antidromic Activation Reveals Tonotopically Organized Projections From Primary Auditory Cortex to the Central Nucleus of the Inferior Colliculus in Guinea Pig
Authors: Lim Hubert H. , Anderson David J.
Published: December 2006

The inferior colliculus (IC) is highly modulated by descending projections from higher auditory and nonauditory centers. Traditionally, corticofugal fibers were believed to project mainly to the extralemniscal IC regions. However, there is some anatomical evidence suggesting that a substantial number of fibers from the primary auditory cortex (A1) project into the IC central nucleus (ICC) and appear to be tonotopically organized. In this study, we used antidromic stimulation combined with other electrophysiological techniques to further investigate the spatial organization of descending fibers from A1 to the ICC in ketamine-anesthetized guinea pigs. Based on our findings, corticofugal fibers originate predominantly from layer V of A1, are amply scattered throughout the ICC and only project to ICC neurons with a similar best frequency (BF). This strict tonotopic pattern suggests that these corticofugal projections are involved with modulating spectral features of sound. Along the isofrequency dimension of the ICC, there appears to be some differences in projection patterns that depend on BF region and possibly isofrequency location within A1 and may be indicative of different descending coding strategies. Furthermore, the success of the antidromic stimulation method in our study demonstrates that it can be used to investigate some of the functional properties associated with corticofugal projections to the ICC as well as to other regions (e.g., medial geniculate body, cochlear nucleus). Such a method can address some of the limitations with current anatomical techniques for studying the auditory corticofugal system.
Pursuit Responses to Target Steps During Ongoing Tracking
Authors: Tarnutzer A. A. , Ramat S. , Straumann D. , Zee D. S.
Published: December 2006

Brief smooth eye-velocity responses to target position steps have been reported during smooth pursuit. We investigated position-error responses in eight healthy human subjects, comparing the effects of a step–ramp change in target position when imposed on steady-state smooth pursuit, vestibuloocular reflex (VOR) slow phases, or fixation. During steady-state pursuit or VOR, the target performed a step–ramp movement in the same or in the opposite direction relative to ongoing eye movements. When the step was directed backward relative to steady-state smooth pursuit, eye velocity transiently decreased (1.3 ± 0.4°/s; average peak change in amplitude ± SD), beginning about 100 ms after the step. The amplitude of position-error responses varied inversely with the step size. In contrast, there was little or no response in trials with forward steps during steady-state smooth pursuit, when step–ramps were imposed on VOR or when smooth pursuit began from fixation. We hypothesize that during ongoing smooth tracking when a sudden shift in target position is detected the pursuit system compares the direction of ongoing eye velocity with the relative positional error on the retina. In the case of different relative directions between ongoing tracking and a new target eccentricity, a position-error response toward the new target is initiated. Such a mechanism might help the smooth pursuit system to respond better to changes in target direction. These experimental findings were simulated by a mathematical model of smooth pursuit by implementing direction-dependent behavior with a position-error gating mechanism.
Loading the Limb During Rhythmic Leg Movements Lengthens the Duration of Both Flexion and Extension in Human Infants
Authors: Musselman Kristin E. , Yang Jaynie F.
Published: December 2006

Sensory input is critical for adapting motor outputs to meet environmental conditions. A ubiquitous force on all terrestrial animals is gravity. It is possible that when performing rhythmic movements, animals respond to load-related feedback in the same way by prolonging the muscle activity resisting the load. We hypothesized that for rhythmic leg movements, the period (extension or flexion) experiencing the higher load will be longer and vary more strongly with cycle period. Six rhythmic movements were studied in human infants (aged 3–10 mo), each providing different degrees of load-related feedback to the legs during flexion and extension of the limb. Kicking in supine provided similar loads (inertial) during flexion and extension. Stepping on a treadmill, kicking in supine against a foot-plate, and kicking in sitting loaded the legs during extension more than flexion, whereas air-stepping and air-stepping with ankle weights did the opposite. Video, electrogoniometry, surface electromyography, and contact forces were recorded. We showed that load-related feedback could make either the duration of flexion or extension longer. Within the tasks of stepping and kicking against a plate, infants who exerted lower forces showed shorter extensor durations than those who exerted higher forces. Because older babies tend to step with greater force, we wished to rule out the contribution of age. Eight babies (>8 mo old) were studied during stepping, in which we manipulated the amount of weight-bearing. The same effect of load was seen. Hence, the degree of loading directly affects the duration of extension in an incremental way.
Neurons in Superficial Trigeminal Subnucleus Caudalis Responsive to Oral Cooling, Menthol, and Other Irritant Stimuli
Authors: Zanotto Karen L. , Merrill Austin W. , Carstens Mirela Iodi , Carstens E.
Published: December 2006

The recent discoveries of cold-sensitive transient receptor potential (TRP) channels prompted us to investigate the responses of neurons in trigeminal subnucleus caudalis (Vc) to intraoral cooling and agonists of TRPM8 and TRPA1. Single units responsive to lingual cooling were recorded in superficial laminae of Vc in thiopental-anesthetized rats. All units responded to noxious heat and 88% responded to menthol. Responses increased with menthol concentration from 0.1 to 1% (6.4–64 mM) and plateaued at 10% (640 mM). Noxious cold-evoked responses were significantly enhanced after menthol in a concentration-dependent manner. Constant-flow application of 1% menthol elicited a phasic discharge that adapted over 2–8 min and significantly enhanced subsequent cold-evoked but not heat-evoked responses; vehicle (10% ethanol) was ineffective. Reapplication of menthol 15 min later elicited a significantly reduced response (self-desensitization). Vc units were similarly excited phasically by 1% menthol dissolved in 40% ethanol. The 40% ethanol briefly excited Vc units during the first minute and reduced subsequent responses to noxious heat and cold while exhibiting neither self-desensitization nor cross-desensitization to menthol. Menthol cross-desensitized Vc responses to 40% ethanol. Most menthol-responsive units also responded to the TRPA1 agonists cinnamaldehyde and mustard oil, and the TRPV1 agonist capsaicin. Units in superficial Vc receive convergent input from primary afferents that express TRPM8, TRPA1, and/or TRPV1 channels, either directly or indirectly via intersubnuclear pathways. The convergent nature of these units suggests a general role in signaling noxious stimuli.
Strain-Specific Nicotinic Modulation of Glutamatergic Transmission in the CA1 Field of the Rat Hippocampus: August Copenhagen Irish Versus Sprague-Dawley
Authors: Alkondon Manickavasagom , Pereira Edna F. R. , Potter Michelle C. , Kauffman Frederick C. , Schwarcz Robert , Albuquerque Edson X.
Published: December 2006

Prepulse inhibition (PPI), a measure of sensorimotor gating impaired in patients with schizophrenia, is more sensitive to disruption by apomorphine in prepubertal August Copenhagen Irish (ACI) than Sprague-Dawley (SD) rats. In brain regions including the hippocampus, PPI is modulated by α7* nicotinic receptors (nAChRs) and kynurenic acid (KYNA), a kynurenine metabolite that blocks α7 nAChRs. Here, KYNA levels and nAChR activities were measured in the hippocampi of 10- to 23-day-old ACI and SD rats of both sexes. Hippocampal KYNA levels were not different between ACI and SD rats. In hippocampal slices from both rat strains, choline (10 mM) evoked α7* nAChR-mediated type IA currents in CA1 stratum radiatum (SR) interneurons. In the presence of α7 nAChR antagonists, acetylcholine (ACh, 1 mM) evoked α4β2* nAChR-mediated type II currents. ACh also triggered excitatory postsynaptic currents (EPSCs) that resulted from α3β4* nAChR activation in glutamatergic neurons/axons synapsing onto the interneurons. The magnitude of the nicotinic responses did not differ significantly between male and female rats. Only the magnitude of α3β4* nAChR responses and the frequency of spontaneous EPSCs recorded from CA1 SR interneurons differed between the rat strains, being significantly larger in ACI than SD rats. These results indicate that the α3β4* nAChR activity in glutamatergic neurons/axons and the number of glutamatergic terminals synapsing onto CA1 SR interneurons are larger in prepubertal ACI than SD rats. The differential sensitivity of these rats to PPI disruption by apomorphine may result from strain-specific levels of glutamatergic activity and its strain-specific modulation by α3β4* nAChRs in the hippocampus.
The Epistle to Diognetus
Authors: Foster Paul
Published: December 2006

The Epistle to Diognetus appears to have been a text that was as keen for self-destruction as a group of lemmings heading for a precipice. Unknown and uncited in the extant writings of the Church Fathers, it was rescued in the fifteenth century just prior to being used to wrap fish. In the nineteenth century it was destroyed by fire. Here the history, teaching and theology of this text, which offers a robust defence of the Christian faith, are discussed.
The First Miracle Resurrected
Authors: Derrett J. D. M.
Published: December 2006

The explanation of John 2.1–11 is obvious if one studies Canticles 7.3(2). The new Israel, stimulated by her Mother, will never lack ‘mixed wine’.
Three Texts about Moses: Numbers 12, 16 and 20
Authors: Gorringe Tim
Published: December 2006

Numbers presents a complex picture of Moses' leadership, which was not based on power dynamics. The stories invite us to reflect on leadership in our own world and in particular on our response to the total market.