bluuebunny/crossref_metadata_2025 huggingface dataset:
Early Maastrichtian carbon cycle perturbation and cooling event: Implications from the South Atlantic Ocean
Authors: Friedrich Oliver , Herrle Jens O. , Wilson Paul A. , Cooper Matthew J. , Erbacher Jochen , Hemleben Christoph
Published: May 2009

Published stable isotope records in marine carbonate are characterized by a positive δ18O excursion associated with a negative δ13C shift during the early Maastrichtian. However, the cause and even the precise timing of these excursions remain uncertain. We have generated high‐resolution foraminiferal stable isotope and gray‐scale records for the latest Campanian to early Maastrichtian (∼73–68 Ma) at two Ocean Drilling Program sites, 525 (Walvis Ridge) and 690 (Weddell Sea). We demonstrate that the negative δ13C excursion is decoupled from the δ18O increase with a lag of about 600 ka. Our δ13C records (both planktic and benthic) show an amplitude for the negative excursion of 0.7‰ that falls between about 72.1 and 70.7 Ma. Our planktic δ18O records indicate an overall increase of 1.2‰ from 73 to 68 Ma at Site 690, whereas at Site 525 they record a slightly smaller increase (∼1‰) that peaks around 70.1 Ma with decreasing values thereafter. Our benthic δ18O data indicate an increase of ∼1.5‰ at Site 525 and ∼0.7‰ at Site 690 between about 71.4 and 69.9 Ma. Benthic δ18O values show different baseline values at the two sites before and after the excursion, but the larger increase at Site 525 means that the values attained at the peak of the excursion are similar at the two sites. We interpret this observation in terms of water mass changes. The excursion is interpreted to reflect a cooling of bottom waters in response to the strengthening contribution of intermediate‐ to deep‐water production in the high southern latitudes rather than increased ice volume. The associated carbon cycle perturbations that we observe are interpreted to reflect a weakening of surface water stratification and increased productivity, as supported by our gray value data.
Shear wave anisotropy beneath Nicaragua and Costa Rica: Implications for flow in the mantle wedge
Authors: Abt David L. , Fischer Karen M. , Abers Geoffrey A. , Strauch Wilfried , Protti J. Marino , González Victor
Published: May 2009

We present new shear wave splitting data from local events in Costa Rica and Nicaragua recorded by the temporary (July 2004 to March 2006) 48‐station TUCAN broadband seismic array. Observed fast polarization directions in the fore arc, arc, and back arc range from arc‐parallel to arc‐normal over very short distances (<5 km when plotted at raypath midpoints) making the direct interpretation of individual splitting measurements in terms of flow tenuous, even when considering variations in the relationship between lattice‐preferred orientation and deformation (e.g., B‐type dislocation creep in olivine). Therefore, we tomographically invert the splitting measurements to find a three‐dimensional model of crystallographic orientation in the wedge. We assume the elastic constants of olivine and orthopyroxene with hexagonal symmetry and use a damped, iterative least squares approach to account for the nonlinear behavior of splitting when considering three‐dimensional ray propagation and distributions of anisotropy. The best fitting model contains roughly horizontal, arc‐parallel olivine [100] axes in the mantle wedge down to at least 125 km beneath the back arc and arc, which we interpret to indicate along‐arc flow in the mantle wedge. Pb and Nd isotopic ratios in arc lavas provide additional evidence for arc‐parallel flow and also constrain the direction (northwest, from Costa Rica to Nicaragua) and minimum flow rate (63–190 mm/a). With only slightly oblique subduction at 85 mm/a of the relatively planar Cocos Plate, the most likely mechanism for driving along‐arc transport is toroidal flow around the edge of the slab in southern Costa Rica, generated by greater slab rollback in Nicaragua. Two important implications of this arc‐parallel flow are the progressive depletion of the mantle source for arc lavas from Costa Rica to Nicaragua and the possible need for significant decoupling between the wedge and downgoing plate.
Spatial aftershock distribution of the 26 December 2004 great Sumatra‐Andaman earthquake in the northern Sumatra area
Authors: Lin Jing‐Yi , Le Pichon Xavier , Rangin Claude , Sibuet Jean‐Claude , Maury Tanguy
Published: May 2009

In July 2005, about 6 months after the 2004 great Sumatra‐Andaman earthquake, 20 ocean bottom seismometers were deployed in the northern Sumatra area. More than 1000 events were identified during the 12 day recording period. After relocation, the seismicity shows different patterns on each side of the Lower Splay Fault. East of this feature and beneath the Aceh basin and fore arc, the deep earthquakes outline the subduction megathrust fault. West of it, the aftershocks distribution is strongly influenced by the active N–S oceanic fracture zones of the subducted plate. Two N–S trending clusters of 10‐ to 50‐km‐deep earthquakes observed below the lower wedge are interpreted as reactivated oceanic fracture zones. The postseismic activity suggests a significant influence of the N–S active fracture zones of the oceanic plate on the toe of the wedge explaining the dextral wrenching of wedge thrusts in the morphology. The megathrust fault does not extend to the trench but outcrops east of these active oceanic fractures and seems to merge upward along the Lower Splay Fault where shallow earthquakes are observed.
Unraveling shallow causes of subsidence
Authors: Muntendam‐Bos A. G. , Kleuskens M. H. P. , Bakr M. , de Lange G. , Fokker P. A.
Published: May 2009

The surface movement in the Krimpenerwaard polder in The Netherlands results from primary or hydrodynamic settlement/swelling, secondary or creep settlement/swelling, and peat oxidation. We used surface movement measurements in a Bayesian inversion scheme to disentangle the contribution of these three processes to the subsidence. The prior information, including spatial correlations, appeared to be crucial in our procedure. This prior information was derived from geological modeling incorporating the most important uncertainties. The inversion procedure allowed us to quantify the contributions of the three processes with unprecedented accuracy. Surface rise in the data was related to swelling of the clay layers, even though swelling was considered infeasible in the prior information. Despite this, the irreversible nature of peat oxidation was preserved. The improved subsurface description offers prospects for identification of incorrect information and for better assessments of the effects of water management.
Size, shape, and orientation of magnetosheath mirror mode structures
Authors: Horbury T. S. , Lucek E. A.
Published: May 2009

Information about the size, shape, and orientation of mirror mode structures in the magnetosheath is obtained by combining data from the four Cluster spacecraft, resulting in an estimate of the form of the magnetic field magnitude spatial autocorrelation function. It is shown that the longest direction of the structures is typically inclined at around 30° from the local magnetic field direction, consistent with predictions based on linear growth theory; their smallest size is also consistent with these predictions. The ratio of the longest to shortest scales of the structures is typically 2–6, with some evidence for this value to decrease as the structures are carried downstream. This suggests that the mirror modes are generated as long structures, but gradually become isotropic, possibly as part of their nonlinear growth. In common with earlier work, we find that the direction in which the structures are shortest is typically well aligned with the local magnetopause normal, consistent with compression against this boundary. However, the maximum variance direction is not a good proxy for the long axis of the structures, typically lying around 25° from it.
Wavelet cross‐spectrum analysis of the ring current using magnetic records from multiple low‐latitude stations
Authors: Xu Z. , Zhu L. , Sojka J. , Kokoszka P.
Published: May 2009

Ground magnetic disturbances in equatorial regions are directly connected to the spatial and temporal variations of the ring currents, which have both the symmetric and asymmetric components, as well as many local‐time‐dependent M‐I currents. In this study, we applied the wavelet analysis technique, which is especially appropriate for the data with impulsive and time‐dependent spectral features, to the magnetic records from multiple low‐latitude stations in order to study the dynamic behaviors of the symmetric and asymmetric parts of the ring currents for both quiet and storm conditions. First, we decomposed the magnetic records into various details in the wavelet spectral domain and systematically studied the temporal and frequency properties of the magnetic disturbances for various geomagnetic and seasonal conditions. Then we performed wavelet cross‐spectrum analysis on the data from multiple stations in both UT and LT time frames in order to separate and elucidate the effects of the symmetric and asymmetric parts of the ring currents. Our results show that slow time‐varying components of the ring current are largely globally symmetric, and during quiet periods, the magnetic effect of this symmetric part is comparable to that of the asymmetric (or local‐time‐dependent) part. During storm periods, the magnetic disturbances associated with both the symmetric and asymmetric parts of the ring currents increase significantly, but the increase of the symmetric ring current is much larger than that of the asymmetric current and it becomes dominant during storm periods. This result is based on the statistical study of multiple‐day timescale variations. For shorter timescales such as the main phase of storms, the asymmetric component could be stronger than symmetric component. Our results also indicate that there are substantial residues of the magnetic effects of local‐time‐dependent currents left in the Dst index, and this further proves that the Dst is not an ideal index for the description of the symmetric ring current.
Digital BioCuration: A Question of Balance
Authors: Ostell James
Published: May 2009

Curation of biomedical data has come to encompass a broad range of activities and considerations, which include the building of digital archives, making decisions on the relative value and longevity of one dataset vs another, editing data records manually, performing or assessing computational processes over very large sets of data, and grappling with issues of web usability and data standards. People who consider themselves biological curators may range from a single domain expert, who develops a collection which reflects their personal judgments and priorities, to groups of people supporting large, long term public resources such as GenBank, RefSeq, or PubMed, and everything in between. Finding the right balance between objective measures of quality and personal judgment, between computational measures and manual curation, between published results in journals and active curation of databases varies by project but some common themes and considerations recur in our experiences of the past two decades at NCBI.
A subalgebra of Lie algebra A2 and its associated two types of loop algebras, as well as Hamiltonian structures of integrable hierarchy
Authors: Huan-he Dong
Published: May 2009

In this paper, a subalgebra Ȧ2 of the Lie algebra A2 is constructed, which gives a corresponding loop algebra A¯2 by properly choosing the gradation of the basis elements. It follows that an isospectral problem is established and a new Liouville integrable Hamiltonian hierarchy is obtained. By making use of a matrix transformation, a subalgebra Ȧ2 of the Lie algebra A1 is presented, which possesses the same communicative operations of basis elements as those in Ȧ2. Again we expand the Lie algebra Ȧ1 into a high-dimensional loop algebra G̃, and a type of expanding integrable system of the hierarchy obtained above is worked out. Furthermore, Hamiltonian structures of hierarchy are presented by use of the quadratic form identity.
Structure and dynamics of S3− radicals in ultramarine-type pigment based on zeolite A: Electron spin resonance and electron spin echo studies
Authors: Goslar Janina , Lijewski Stefan , Hoffmann Stanisław K. , Jankowska Aldona , Kowalak Stanisław
Published: May 2009

X -band electron spin resonance (ESR) spectra of S3− radicals in ultramarine analog (pigment) prepared from zeolite A and maintaining the original structure of parent zeolite were recorded in the temperature range of 4.2–380 K. Electron spin echo experiments (echo detected ESR, electron spin-lattice relaxation, and spin echo dephasing) were performed in the temperature range of 4.2–50 K. The rigid lattice g factors are gx=2.0016, gy=2.0505, and gz=2.0355, and they are gradually averaged with temperature to the final collapse into a single line with g=2.028 above 300 K. This is due to reorientations of S3− molecule between 12 possible orientations in the sodalite cage through the energy barrier of 2.4 kJ/mol. The low-lying orbital states of the open form of S3− molecule having C2v symmetry are considered and molecular orbital (MO) theory of the g factors is presented. The orbital mixing coefficients were calculated from experimental g factors and available theoretical orbital splitting. They indicate that the unpaired electron spin density in the ground state is localized mainly (about 50%) on the central sulfur atom of S3− anion radical, whereas in the excited electronic state the density is localized mainly on the lateral sulfur atoms (90%). A strong broadening of the ESR lines in directions around the twofold symmetry axis of the radical S3− molecule (z-axis) is discovered below 10 K. It is due to a distribution of the S–S–S bond angle value influencing mainly the energy of the B22-symmetry MO. This effect is smeared out by molecular dynamics at higher temperatures. A distribution of the g factors is confirmed by the recovery of the spin system magnetization during spin-lattice relaxation measurements, which is described by a stretched exponential function. Both the spin-lattice relaxation and electron spin echo dephasing are governed by localized phonon mode of energy of about 40 cm−1. Thus, the anion-radical S3− molecules are weakly bonded to the zeolite framework, and they do not participate in the phonon motion of the host lattice because of their own local dynamics.
Properties of the far-field operator for a multilayered scatterer in acoustic scattering theory
Authors: Dinlemez Ülkü , Torun Gülten
Published: May 2009

In this paper, we consider the inverse scattering problem which is to determine the shape of a multilayered scatterer. The adjoint of the far-field operator is found. In scattering theory the boundary data are given by the traces of plane waves. The closure of the span of the images of these plane waves under the far-field operator is characterized. Furthermore, taking the affine hull instead of the span of the plane waves on the boundary, some results are obtained.
Transmittance and optical constants of Tm films in the 2.75–1600 eV spectral range
Authors: Vidal-Dasilva Manuela , Fernández-Perea Mónica , Aznárez José A. , Larruquert Juan I. , Méndez José A. , Poletto Luca , Malvezzi A. Marco , Giglia Angelo , Nannarone Stefano
Published: May 2009

The optical constants of thulium (Tm) films were obtained in the 2.75–1600 eV range from transmittance measurements performed at room temperature. Thin films of Tm were deposited by evaporation in ultrahigh vacuum conditions and their transmittance was measured in situ. Tm films were deposited onto grids coated with a thin, C support film. Transmittance measurements were used to obtain the optical extinction coefficient k of Tm films. The refractive index n of Tm was calculated using the Kramers–Krönig analysis. k data were extrapolated both on the high and the low energy sides by using experimental and calculated extinction coefficient values available in the literature. Tm, similar to other lanthanides, has a low-absorption band below the O2,3 edge onset; the lowest absorption was measured at ∼23 eV. Therefore, Tm is a promising material for filters and multilayer coatings in the energy range below the O2,3 edge in which materials typically have an absorption stronger than away. Good consistency of the data was obtained through f and inertial sum rules.
Determination of reversible permeability in the presence of a strong bias field
Authors: Momeni Sepandarmaz , Konrad Adalbert , Sinclair Anthony N.
Published: May 2009

A new method is developed to measure reversible permeability as a function of frequency and bias field for application to modeling of magnetostrictive electromagnetic acoustic transducer; these transducers are used for ultrasonic nondestructive evaluation of magnetic materials. The method is based on a new model developed to predict the impedance of a rectangular eddy current coil when placed in proximity to a ferromagnetic specimen; inputs to this model are geometry of the coil, frequency, permeability, and conductivity of the specimen. This method was applied to a specimen of SAE1018 carbon steel. Experimental measurements of the specimen impedance, combined with the new theoretical model, enabled the reversible permeability to be determined in the presence of bias field levels ranging from 0 to 46 000 A/m and frequencies ranging from 350 kHz to 1.1 MHz. Frequency and bias field dependence of reversible permeability for this specimen is consistent with a model of magnetic domain rotation and wall movement.
Microwave excitation of localized electrons in phosphorus-doped silicon single electron transistors
Authors: Creswell L. A. , Hasko D. G. , Williams D. A.
Published: May 2009

We investigate the effect of microwave irradiation on the source-drain current of a silicon single electron transistor, with fixed source-drain and gate voltages, at a temperature of 4 K. The source-drain current can be increased, decreased, or even reversed by the radiation, depending on the microwave frequency and dc bias conditions. Some of the source-drain current changes take the form of sharp resonances with high quality factor. We investigate the effect of the microwave irradiation coupling method on the form of these resonances. The coupling method does not modify the center frequency of the resonances however it does alter the resonance shape. We discuss the origin of these resonant features and propose that they originate from the microwave induced spatial redistributions of localized electrons in the single electron transistor.
Understanding pressure-induced phase-transformation behavior in silicon through in situ electrical probing under cyclic loading conditions
Authors: Fujisawa N. , Ruffell S. , Bradby J. E. , Williams J. S. , Haberl B. , Warren O. L.
Published: May 2009

Cyclic indentation of crystalline silicon exhibits interesting pressure-induced phase-transformation behavior whereby sequential changes in the phase composition ultimately lead to a catastrophic (“pop-out”) event during subsequent cycles and complete transformation to high pressure Si-III and Si-XII phases. This study combines in situ electrical measurements with cyclic loading to monitor such phase-transformation behavior. We find that, if a pop-out is not observed on the unloading curve, the end phase is predominantly amorphous but a small and increasing volume of Si-III/Si-XII results with each cycle. At a critical Si-III/Si-XII volume, pop-out can occur on a subsequent cycle, whereafter Si-III/Si-XII dominates the indent volume.
Maximum windmill efficiency in finite time
Authors: Huleihil Mahmoud
Published: May 2009

The fraction of the kinetic energy of the wind impinging on the rotor-swept area that a wind turbine can convert to useful power has been shown by Betz in an idealized laminar-flow model to have an upper limit of 16/27 or 59% approximately [I. H. Shames, Mechanics of Fluids, 2nd ed. (McGraw-Hill, New York, 1982), pp. A26–A31]. This figure is known as Betz number. Other studies [A. Rauh and W. Seelret, Appl. Energy 17, 15 (1984)] suggested that this figure should be considered as a guideline. In this paper, a new model is introduced and its efficiency at maximum power output is derived. The derived value is shown to be a function of the Betz number B and given by the formula ηmp=1−1−B. This value is 36.2%, which agrees well with those of actually operating wind turbines. As a guideline, the wind turbine efficiency can be considered to be within the range of the two numbers of merit, the Betz number and ηmp.
Ultrathin SiO2 layer with an extremely low leakage current density formed in high concentration nitric acid
Authors: Kim Woo-Byoung , Matsumoto Taketoshi , Kobayashi Hikaru
Published: May 2009

An ultrathin silicon dioxide (SiO2) layer of 1.2–1.4 nm thickness has been formed by immersion of Si wafers in nitric acid (HNO3) aqueous solutions, and its electrical characteristics and physical properties are investigated as a function of the HNO3 concentration. Measurements of transverse optical and longitudinal optical phonons of Si–O–Si asymmetric stretching vibrational mode for SiO2 indicate that the atomic density of the SiO2 layer increases with the HNO3 concentration. X-ray photoelectron spectroscopy measurements show that the valence band discontinuity energy at the SiO2/Si interface also increases and the concentration of suboxide species decreases with the HNO3 concentration. The leakage current density of the ⟨Al/SiO2/Si(100)⟩ metal-oxide-semiconductor (MOS) diodes with the SiO2 layer formed in HNO3 aqueous solutions decreases with the HNO3 concentration and also decreases by postmetallization annealing (PMA) treatment at 250 °C in 5 vol % hydrogen atmosphere. For the MOS diodes with the SiO2 layer formed in 98 wt % HNO3, the leakage current density measured after PMA is much lower than that for thermally grown SiO2 with the same thickness and even lower than that for silicon oxynitride with the same effective oxide thickness. The decrease in the leakage current density by PMA is attributed to (i) elimination of interface states, (ii) elimination of slow states, and (iii) increase in the band discontinuity energy at the SiO2/Si interface.
Curvature effect on the phonon thermal conductivity of dielectric nanowires
Authors: Liu Liang-Chun , Huang Mei-Jiau , Yang Ronggui , Jeng Ming-Shan , Yang Chang-Chung
Published: May 2009

Phonon thermal conductivity of nanowires is very different from bulk materials and is of great importance to the applications of nanowires in nanoelectronics, sensors, and energy conversion and storage. Past theoretical studies usually assume that nanowires are perfectly straight and so as the analysis of experimental data. However, nanowires are not always straight with regards to both characterization and application. The curvature of nanowires could significantly change the thermal conductivity and thus bring uncertainty in characterization and product reliability due to its effect on ballistic phonon transport. In this study, the curvature effect on phonon thermal conductivity of dielectric nanowires is investigated using a phonon transport Monte Carlo simulator. It is found that the curvature impedes ballistic phonon transport in nanowires, causes an increase in the effective transport length of the thermal resistor, and thus reduces the effective thermal conductivity of nanowires. Such geometrical effect could be utilized as a new mechanism to tune the thermal conductivity of nanostructures.
Effect of the hydrophobicity and thickness of polymer gate dielectrics on the hysteresis behavior of pentacene-based field-effect transistors
Authors: Kim Se Hyun , Nam Sooji , Jang Jaeyoung , Hong Kipyo , Yang Chanwoo , Chung Dae Sung , Park Chan Eon , Choi Woon-Seop
Published: May 2009

We demonstrate the origin and mechanism of the hysteresis behavior that is frequently observed during the operation of organic field-effect transistors (OFETs) based on polymer gate dielectrics. Although polar functionalities, such as hydroxyl groups, present in the polymer gate dielectrics are known to induce hysteresis, there have only been a few detailed investigations examining how the presence of such end functionalities both at the polymer surface—forming an interface with the semiconductor layer—and in the bulk influences the hysteresis. In this study, we control the hydrophobicity of the polymer by varying the number of hydroxyl groups, and use an ultrathin polymer/SiO2 bilayer and a thick single polymer as the gate dielectric structure so that the hysteresis behavior is divided into contributions from hydroxyl groups present at the polymer surface and in the bulk, respectively. Electrical characterizations of the OFETs, performed both in vacuum (≈10−3 Torr) and in ambient air (relative humidity of about 40%), show that the observed hysteresis is determined by the transport of water within the polymer (i.e., the adsorption at the polymer surface and the diffusion into the bulk), which in turn is controlled by the hydrophobicity and the thickness of the polymer.
Universal fermionization of bosons on permutative representations of the Cuntz algebra O2
Authors: Kawamura Katsunori
Published: May 2009

Bosons and fermions are described by using canonical generators of Cuntz algebras on any permutative representation. We show a fermionization of bosons which universally holds on any permutative representation of the Cuntz algebra O2. As examples, we show fermionizations on the Fock space and the infinite wedge.
Laser ablation of aluminum from normal evaporation to phase explosion
Authors: Gragossian A. , Tavassoli S. H. , Shokri B.
Published: May 2009

A study of laser ablation of Aluminum sample by nanosecond laser pulses considering two simultaneous mechanisms of normal evaporation and phase explosion is theoretically carried out. The temperature distribution in the sample is calculated by a one dimensional heat conduction equation. Ablation depth due to the evaporation and explosion is calculated as a function of laser pulse energies. Variation in some effective sample parameters during the laser ablation and their effects on laser ablation mechanisms are taken into account. At low irradiance, ablation is mainly due to the evaporation, while after a threshold intensity, the phase explosion becomes the dominant mechanism. Theoretical results of transition from the normal evaporation to the phase explosion are in good agreement with the experimental results.
Effects of nitrogen vacancies on transition-metal-doped GaN: An ab initio study
Authors: Xu B. , Pan B. C.
Published: May 2009

The effects of N vacancies on the transition metal (Cr, Mn, Fe, Co, Ni, and Cu) doped GaN have been studied at the levels of the local spin density approximation (LSDA) and LSDA+U (Coulomb interaction). Our calculations show that the N vacancy favorably exists near a transition metal ion and the interaction between transition metal ion and N vacancy is insensitive to the distance when exceeding 3.3 Å. Furthermore, we find that the existed N vacancies alter the magnetic moments of the doped GaN, where the magnetic moments increase for Cr or Mn doped GaN, and decrease for Fe, Co, Ni, or Cu doped GaN. This result can be interpreted well by the Hund’s multiplicity rules. However, it is found that the magnetic moments of doped GaN with N vacancies are insensitive to the distances between N vacancies and the doped transition metal ions. Our obtained results are useful to elucidate the effects of N vacancies on the magnetic properties of the transition metal doped GaN.
Possible incipient ferroelectricity in Mn-doped Na1/2Bi1/2Cu3Ti4O12
Authors: Ferrarelli Matthew C. , Sinclair Derek C. , West Anthony R.
Published: May 2009

The grain semiconductivity of Na1/2Bi1/2Cu3Ti4O12 ceramics is suppressed by several orders of magnitude by Mn-doping and Na1/2Bi1/2Cu2.82Mn0.18Ti4O12 ceramics exhibit high room temperature relative permittivity, εr, ∼140. εr data at 100 kHz fit the Barrett equation over the range ∼10–320 K and the magnitude and temperature dependence of εr are consistent with incipient ferroelectricity in this compound.
Driving toroidally asymmetric current through the tokamak scrape-off layer. I. Potential for edge localized mode suppression
Authors: Joseph Ilon , Cohen Ronald H. , Ryutov Dmitri D.
Published: May 2009

A potential technique for suppressing edge localized modes is theoretically analyzed. Recent experiments have shown that externally generated resonant magnetic perturbations (RMPs) can stabilize edge localized modes (ELMs) by modifying the density profile [T. E. Evans et al., Nat. Phys. 2, 419 (2006); Y. Liang et al., Phys. Rev. Lett. 98, 265004 (2007)]. Driving toroidally asymmetric current internally through the scrape-off layer (SOL) plasma itself can also generate RMPs that are close to the required threshold for ELM control. Ion saturation current densities can be achieved by producing potential differences on the order of the electron temperature. Although the threshold is uncertain in future devices, if driven coherently through the SOL, the upper limit for the resulting perturbation field would exceed the present experimental threshold. This analysis provides the tools required for estimating the magnitude of the coherent SOL current and RMP generated via toroidally asymmetric biasing of the target. Flux expansion increases the perturbation near the X-point, while phase interference due to the shearing of field lines near the X-point reduces the amplitude of the effective SOL perturbation and makes the result sensitive to both toroidal mode number n and the phasing at the target plate. If the current density driven at the target plate decays radially, the amplitude over the useful coherence width of the current profile will be reduced. The RMP can still exceed the present threshold at low n if the radial location and width of the biasing region are optimally chosen.
Relaxation effects in low density amorphous ice: Two distinct structural states observed by neutron diffraction
Authors: Winkel K. , Bowron D. T. , Loerting T. , Mayer E. , Finney J. L.
Published: May 2009

Neutron diffraction with H/D isotopic substitution is used to investigate the structure of low density amorphous ice produced from (1) high density amorphous ice by isobaric warming and (2) very high density amorphous ice by isothermal decompression. Differences are found in the scattering patterns of the two low density amorphous ices that correlate with structural perturbations on intermediate length scales in the hydrogen bonded water network. Atomistic modeling suggests that the structural states of the two samples may relate to a competition between short range and intermediate range order and disorder. This structural difference in two low density amorphous (LDA) ices is also evident when comparing their compression behavior. In terms of the energy landscape formalism this finding implies that we have produced and characterized the structural difference of two different basins within the LDA-megabasin corresponding to identical macroscopic densities.
High angular tolerant color filter using subwavelength grating
Authors: Cheong Byoung-Ho , Prudnikov O. N. , Cho Eunhyoung , Kim Hae-Sung , Yu Jaeho , Cho Young-Sang , Choi Hwan-Young , Shin Sung Tae
Published: May 2009

A reflective color filter based on a two-dimensional subwavelength grating is proposed. The filter has been designed by performing numerical simulations and has been fabricated on 5×5 mm2 quartz glass using electron beam lithography. The grating color filter shows reflectance of 74% and spectral width of about 80 nm. Furthermore, it has good angular tolerance, up to ±45°, for unpolarized incident light. By analyzing the reflectance spectral distributions in the band diagram, we found that high angular tolerance is achieved due to the high refractive index contrast of grating structures.
GaN
/
In
1
−
x
Ga
x
N
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GaN
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ZnO
nanoarchitecture light emitting diode microarrays
Authors: Lee Chul-Ho , Yoo Jinkyoung , Hong Young Joon , Cho Jeonghui , Kim Yong-Jin , Jeon Seong-Ran , Baek Jong Hyeob , Yi Gyu-Chul
Published: May 2009

We studied the fabrication and electroluminescent (EL) characteristics of GaN/In1−xGaxN/GaN/ZnO nanoarchitecture light emitting diode (LED) microarrays consisting of position-controlled GaN/ZnO coaxial nanotube heterostructures. For the fabrication of nanoarchitecture LED arrays, n-GaN, GaN/In0.24Ga0.76N multiquantum well (MQW) structures and p-GaN layers were deposited coaxially over the entire surface of position-controlled ZnO nanotube arrays grown vertically on c-plane sapphire substrates. The nanoarchitecture LEDs exhibited strong green and blue emission from the GaN/GaN/In0.24Ga0.76N MQWs at room temperature. Furthermore, the origins of dominant EL peaks are also discussed.
Photon management by metallic nanodiscs in thin film solar cells
Authors: Rockstuhl Carsten , Lederer Falk
Published: May 2009

We investigate the absorption enhancement by metallic nanodiscs in thin-film amorphous silicon solar cells. The effect is quantitatively evaluated by rigorously solving Maxwell’s equations. We show that 50% more photons can be absorbed using geometries accessible for current nanofabrication technologies. Moreover, the thinner the solar cell, the larger the absorption enhancement. Detailed investigations prove that the enhancement can be related to the excitation of localized plasmon polaritons. The simultaneous enhancement in both the near-field amplitude and the scattering cross section at resonance as the leading physical mechanism is discussed in detail.
Hot-electron characteristics in chemically resolved electrical measurements of thin silica and SiON layers
Authors: Rozenblat A. , Rosenwaks Y. , Cohen H.
Published: May 2009

We use the recently developed chemically resolved electrical measurements (CREM) to sensitively measure hot-electron transport characteristics in thin dielectric layers. By comparing bare gate-oxide layers, SiO2 and SiON, pronounced differences are revealed that are absent from standard contact measurements and from CREM conducted on top metallic pads. The “on pad” and standard measurements obey a similar defect-assisted “Poole–Frenkel” transport, whereas I∼Vα characterizes the hot-electron transport through the bare overlayer, with a clear thickness dependence of α. These unique CREM features offer useful advantages in gate-oxide characterization.
Endurance enhancement of Cu-oxide based resistive switching memory with Al top electrode
Authors: Lv Hangbing , Wang Ming , Wan Haijun , Song Yali , Luo Wenjing , Zhou Peng , Tang Tingao , Lin Yinyin , Huang R. , Song S. , Wu J. G. , Wu H. M. , Chi M. H.
Published: May 2009

We investigated the switching performance of Cu-oxide films with Al, Pt, and Ti electrodes. Compared with Pt electrode, the Al electrode shows better stability, preferable endurance, and larger resistance ratio. An interface AlOx layer is detected by transmission electron microscopy and Auger electron spectroscopy. This layer can strongly affect the movement of oxygen vacancies. However, the sample with pure Ti electrode almost has no switching characteristics. Ti/TiN electrode with thin Ti exhibits good switching behavior. The thickness control of Ti layer is quite critical. So we suggest that the oxygen diffusion in electrode is another important factor for switching performance.
Enhancement in hole current density on polarization in poly(3-hexylthiophene):cadmium selenide quantum dot nanocomposite thin films
Authors: Kumari Kusum , Chand Suresh , Vankar V. D. , Kumar Vikram
Published: May 2009

We demonstrate the effect of polarization on space charge limited J-V behavior in poly(3-hexylthiophene) (P3HT):cadmium selenide (CdSe) (∼5 nm) quantum dot nanocomposite thin films in hole-only device configuration, indium tin oxide/poly(ethylene-dioxthiophene):polystyrenesulphonate/P3HT:CdSe/Au. Current density has been found to enhance in these hybrid films on polarization. This has been attributed to decrease in characteristic trap energy from 32 to 27 meV, trap density from 1.7×1018 to 1×1018 cm−3 and increase in hole mobility from 2.6×10−6 to 7.7×10−6 cm2 V−1 s−1 due to field induced enhanced order by dipolar alignment and/or trapping of charge carriers at the nanoscale interfacial boundaries of P3HT and CdSe quantum dots.
The impact of intermediate reflectors on light absorption in tandem solar cells with randomly textured surfaces
Authors: Rockstuhl C. , Lederer F. , Bittkau K. , Beckers T. , Carius R.
Published: May 2009

The impact of dielectric intermediate reflectors on the light absorption in the top cell of an a-Si:H/μc-Si:H tandem solar cell comprising randomly textured surfaces was investigated by rigorous diffraction theory. Despite the strong light scattering, we found Fabry–Pérot oscillations for the absorption with a decreasing modulation for an increasing thickness of the intermediate layer, a larger oscillation period when compared to thin films and a homogenization of the absorption profile. Optimized intermediate reflectors generate an absorption enhancement in the a-Si:H film, which varies between a factor of 2 and more than 3 for wavelengths of strong and weak absorption, respectively.
Improved performance of InAlN-based Schottky solar-blind photodiodes
Authors: Chen Z. T. , Tan S. X. , Sakai Y. , Egawa T.
Published: May 2009

The authors report the growth of InxAl1−xN with high crystal quality by metal organic chemical vapor deposition, the Pd/InxAl1−xN Schottky contacts with reverse current densities as low as 6.0×10−7 A/cm2 at −5 V and 2.1×10−5 A/cm2 at −10 V, and consequently significant improvement in the performance of InAlN-based Schottky solar-blind photodiodes with peak responsivity of 133 mA/W at 242 nm, corresponding to a quantum efficiency of 68.5%. The illumination is detectable under the intensity as weak as 10 nW/cm2. The rejection ratios by 300 nm are one order of magnitude for 10 nW/cm2 illumination and three orders of magnitude for 1 μW/cm2 illumination.
The Software Slump?: Digital Music, the Democratisation of Technology, and the Decline of the Recording Studio Sector within the Musical Economy
Authors: Leyshon Andrew
Published: May 2009

The music industry has been radically transformed by software. As has now been well documented, the development of software formats such as MP3 and the rise of Internet ‘piracy’ have had significant impacts upon intellectual property rights and distribution within the industry, with significant impacts for record companies. This paper explores another part of the musical economy which has also been radically transformed through code, although, to date, this crisis has passed by with very little comment. The paper looks at the recording studio sector and reveals how the introduction of software into the recording process encouraged a vertical disintegration of production in musical agglomerations from the late 1970s onwards and, in so doing, helped leading recording centres to strengthen their hold on the market for recording budgets. However, the impact of software since the mid-1990s has been less benign for such centres. The rise of more affordable digital recording rigs and easier programming protocols represents a democratisation of technology, making available a process that was once accessible only through the facilities and skills provided by a recording studio. Software and code have ushered in a regime of distributed musical creativity, which is having significant impacts on the organisation of the musical economy. As a result, the recording studio sector is undergoing a severe crisis which has produced a spate of studio closures, redundancies, and underemployment within musical agglomerations. As a result, the ‘institutional thickness’ of key recording centres has been significantly depleted in recent years.
Infrastructures of the Imagined Island: Software, Mobilities, and the Architecture of Caribbean Paradise
Authors: Sheller Mimi
Published: May 2009

Software is receding and rescaling island space, assembling islands in new configurations of territoriality and governance. Paying attention to software-supported mobility, sovereignty and place-making offers a key terrain for thinking about the contemporary rescaling of Caribbean states, island territories, and the imaginary ‘offshore’ economies within them. Travel and leisure destinations, especially in the Caribbean, are being disembedded from national territories and repackaged as unique natural enclaves connected to global metropolitan transport, media, and data flows. Through a discussion of Zaha Hadid's masterplan for a new resort on Dellis Cay in the Turks and Caicos Islands, the author explores how state space, informational space, and tourist space are converging in new fantasies of mobility, accessibility, and island paradise. The new software- supported spatialities, theorized as urban or metropolitan, are actually affecting remote Caribbean islands and other dispersed enclaves as much as (though in different ways than) ‘advanced’ urban regions. Indeed, as Caribbean states and territories adjust to complex new infrastructures and architectures of mobility, the deformations and refoldings of space described here may precociously prefigure processes of postcolonial urbanism that are restructuring private property, cyberspatial property, and state territory in other parts of the world.
Debt, Discipline, and Government: Foreclosure and Forbearance in the Subprime Mortgage Crisis
Authors: Langley Paul
Published: May 2009

The extensive punishment of debtors through foreclosure, and federal and state support for forbearance by lenders and loan servicers, are key features of the subprime mortgage crisis in the United States of America. From a Foucauldian perspective, foreclosure and forbearance give rise to questions about the production and reproduction of subprime mortgage debt through disciplinary and governmental power relations—questions that are neglected in the dominant understanding of subprime as an anomalous and unregulated market realm where predatory lenders preyed on borrowers. In addressing these questions I make a two-stage argument. First, I show subprime to have been largely unexceptional in the ways in which it was governed as a legitimate and highly profitable part of a mass mortgage market prior to the crisis: legal processes of foreclosure combined with disciplinary technologies for the calculation of risk and the calling up of responsible, entrepreneurial, and self-disciplined financial subjects. Second, it follows that forbearance, as an apparently progressive response to the crisis, is actually deeply ambivalent and more politically problematic than activists and supporters typically acknowledge. Forbearance does suspend disciplinary norms, opening up space for disagreement over whether lenders should be coresponsible with borrowers for the reproduction of mortgages into the future. But, simultaneously, forbearance closes down the prospects for coresponsibility beyond immediate debt rescheduling, and reinforces the legal, calculate, and self-disciplinary operation of power.
The Local Integration of Employment Services: Assessing Network Effectiveness of Local Job Centres in Flanders
Authors: Struyven Ludo , Van Hemel Line
Published: May 2009

In the Flemish region of Belgium, as in many other countries, the network paradigm is the emerging model for the establishment of local job centres. Based on a one-stop service model, similar basic work-focused services which were previously offered by separate organisations are now integrated and locally embedded. What is the added value of the local establishment of public service delivery based on the network paradigm? This question is answered by using a set of evaluation criteria which we derive from Provan and Milward's framework for evaluating the effectiveness of local, public service networks for health care and welfare. The objective of this research is twofold: (a) a methodological assessment of Provan and Milward's framework; and (b) the empirical evaluation of job centres' effectiveness. Our empirical analysis is based on a mixed method approach, combining registration and organisational data analyses with qualitative findings as reported by stakeholders. We conclude that the network effectiveness of the job centres in Flanders for the year 2006 is not unanimously positive.
Induction of alternative lengthening of telomeres-associated PML bodies by p53/p21 requires HP1 proteins
Authors: Jiang Wei-Qin , Zhong Ze-Huai , Nguyen Akira , Henson Jeremy D. , Toouli Christian D. , Braithwaite Antony W. , Reddel Roger R.
Published: May 2009

Alternative lengthening of telomeres (ALT) is a recombination-mediated process that maintains telomeres in telomerase-negative cancer cells. In asynchronously dividing ALT-positive cell populations, a small fraction of the cells have ALT-associated promyelocytic leukemia nuclear bodies (APBs), which contain (TTAGGG)n DNA and telomere-binding proteins. We found that restoring p53 function in ALT cells caused p21 up-regulation, growth arrest/senescence, and a large increase in cells containing APBs. Knockdown of p21 significantly reduced p53-mediated induction of APBs. Moreover, we found that heterochromatin protein 1 (HP1) is present in APBs, and knockdown of HP1α and/or HP1γ prevented p53-mediated APB induction, which suggests that HP1-mediated chromatin compaction is required for APB formation. Therefore, although the presence of APBs in a cell line or tumor is an excellent qualitative marker for ALT, the association of APBs with growth arrest/senescence and with “closed” telomeric chromatin, which is likely to repress recombination, suggests there is no simple correlation between ALT activity level and the number of APBs or APB-positive cells.
Rescue of skeletal muscle α-actin–null mice by cardiac (fetal) α-actin
Authors: Nowak Kristen J. , Ravenscroft Gianina , Jackaman Connie , Filipovska Aleksandra , Davies Stefan M. , Lim Esther M. , Squire Sarah E. , Potter Allyson C. , Baker Elizabeth , Clément Sophie , Sewry Caroline A. , Fabian Victoria , Crawford Kelly , Lessard James L. , Griffiths Lisa M. , Papadimitriou John M. , Shen Yun , Morahan Grant , Bakker Anthony J. , Davies Kay E. , Laing Nigel G.
Published: May 2009

Skeletal muscle α-actin (ACTA1) is the major actin in postnatal skeletal muscle. Mutations of ACTA1 cause mostly fatal congenital myopathies. Cardiac α-actin (ACTC) is the major striated actin in adult heart and fetal skeletal muscle. It is unknown why ACTC and ACTA1 expression switch during development. We investigated whether ACTC can replace ACTA1 in postnatal skeletal muscle. Two ACTC transgenic mouse lines were crossed with Acta1 knockout mice (which all die by 9 d after birth). Offspring resulting from the cross with the high expressing line survive to old age, and their skeletal muscles show no gross pathological features. The mice are not impaired on grip strength, rotarod, or locomotor activity. These findings indicate that ACTC is sufficiently similar to ACTA1 to produce adequate function in postnatal skeletal muscle. This raises the prospect that ACTC reactivation might provide a therapy for ACTA1 diseases. In addition, the mouse model will allow analysis of the precise functional differences between ACTA1 and ACTC.