bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of children with intellectual giftedness and reading disabilities
Authors: Volker Martin A. , Lopata Christopher , Cook‐Cottone Catherine
Published: September 2006

This article discusses the current issues involved in the evaluation of children who have both intellectual gifts and a specific learning disability (SLD) in reading. Given recent changes in federal special education law (i.e., the Individuals With Disabilities Education Improvement Act of 2004), the use of a unified assessment model that integrates responsiveness to intervention techniques with state‐of‐the‐art psychometric tools is most appropriate for this population. Use of the Cattell‐Horn‐Carroll (K.S. McGrew, 2005) and the Planning, Attention, Simultaneous, Successive (J.A. Naglieri & J.P. Das, 1997b) cognitive assessment theories are highlighted due to their clear relevance to the assessment of both intellectual strengths for gifted children and psychological processing weaknesses for children with SLDs. Recommendations for assessment practices and areas in need of further research are explicitly stated. © 2006 Wiley Periodicals, Inc. Psychol Schs 43: 855–869, 2006.
The TerraMax autonomous vehicle
Authors: Braid Deborah , Broggi Alberto , Schmiedel Gary
Published: September 2006

The TerraMax vehicle is based on Oshkosh Truck's Medium Tactical Vehicle Replacement truck platform and was one of the five vehicles able to successfully reach the finish line of the 132 miles DARPA Grand Challenge desert race. Due to its size (30 000 pounds,27′0″long,8′4″wide, and8′2″high) and the narrow passages, TerraMax had to travel slowly, but its capabilities demonstrated the maturity of the overall system. Rockwell Collins developed, integrated, and installed the intelligent Vehicle Management System, which includes vehicle sensor management, navigation, and vehicle control systems. The University of Parma provided the vehicle's vision system, while Oshkosh Truck Corp. provided project management, system integration, low level controls hardware, modeling and simulation support, and the vehicle. © 2006 Wiley Periodicals, Inc.
How Supplemental Instruction benefits faculty, administration, and institutions
Authors: Zerger Sandra , Clark‐Unite Cathy , Smith Liesl
Published: September 2006

This chapter offers a case study of the Nelson Mandela Metropolitan University, South Africa, where SI has acted as more than a student academic development program by also addressing faculty and curriculum development.
A traffic control system for IEEE 802.11 networks based on available bandwidth estimation
Authors: Ko Dukju , Han Seungjae , Cha Hojung , Ha Rhan
Published: September 2006

To support Quality of service (QoS)‐sensitive applications like real‐time video streaming in IEEE 802.11 networks, a MAC layer extension for QoS, IEEE 802.11e, has been recently ratified as a standard. This MAC layer solution, however, addresses only the issue of prioritized access to the wireless medium and leaves such issues as QoS guarantee and admission control to the traffic control systems at the higher layers. This paper presents an IP‐layer traffic control system for IEEE 802.11 networks based on available bandwidth estimation. We build an analytical model for estimating the available bandwidth by extending an existing throughput computation model, and implement a traffic control system that provides QoS guarantees and admission control by utilizing the estimated available bandwidth information. We have conducted extensive performance evaluation of the proposed scheme via both simulations and measurements in the real test‐bed. The experiment results show that our estimation model and traffic control system work accurately and effectively in various network load conditions without IEEE 802.11e. The presence of IEEE 802.11e will allow even more efficient QoS provision, as the proposed scheme and the MAC layer QoS support will complement each other. Copyright © 2006 John Wiley & Sons, Ltd.
Application of PCR–DGGE to analyse the yeast population dynamics in slurry reactors during degradation of polycyclic aromatic hydrocarbons in weathered oil
Authors: Hesham Abd El‐Latif , Khan Sardar , Liu XinChun , Zhang Yu , Wang Zhenyu , Yang Min
Published: September 2006

Slurry‐phase reactors have been used to investigate the biodegradation feasibility of polycyclic aromatic hydrocarbons (PAHs) in weathered crude oil, by mixed culture containing five PAHs‐degrading yeast strains. Yeasts were isolated from the oily soil by enrichment culture, using phenanthrene as a sole carbon source, and identified based on the 26S ribosomal DNA (rDNA) sequence. Yeast strains belonged to the genera Candida, Pichia, Rhodotorula and Sporidiobolus. The experiment was carried out for a period of 6 weeks at room temperature with a solid : liquid ratio of 50% w/w. The results showed that high removal efficiency was obtained for all PAHs, including low molecular weight (LMW) and high molecular weight (HMW) compounds (89.3–98.6% and 66.3–89.4% within 6 weeks, respectively). The higher removal efficiency for HMW‐PAHs obtained in this work suggested that yeast strains mixture could play an important role to reclaim oil‐contaminated sites. Denaturing gradient gel electrophoresis (DGGE) of polymerase chain reaction (PCR)‐amplified 26S rRNA genes was used to follow the changes of yeast populations during the slurry reactor process. The results of DGGE indicated that Candida maltosa‐like and Pichia guilliermondii were the dominant species but Rhodotorula dairenensis appeared as a weak band and Sporidiobolus salmonicolor and Pichia anomala disappeared during the study. Moreover, the results showed that all of the five strains, including the two belonging to the same genus, could be differentiated from each other in the DGGE profile. Sequences of yeast isolates reported in this study have been deposited in the GenBank database under Accession Nos DQ302753, DQ303392, DQ303393, DQ350841 and DQ432635. Copyright © 2006 John Wiley & Sons, Ltd.
The Attack of the Psychometricians
Authors: Borsboom Denny
Published: September 2006

This paper analyzes the theoretical, pragmatic, and substantive factors that have hampered the integration between psychology and psychometrics. Theoretical factors include the operationalist mode of thinking which is common throughout psychology, the dominance of classical test theory, and the use of “construct validity” as a catch-all category for a range of challenging psychometric problems. Pragmatic factors include the lack of interest in mathematically precise thinking in psychology, inadequate representation of psychometric modeling in major statistics programs, and insufficient mathematical training in the psychological curriculum. Substantive factors relate to the absence of psychological theories that are sufficiently strong to motivate the structure of psychometric models. Following the identification of these problems, a number of promising recent developments are discussed, and suggestions are made to further the integration of psychology and psychometrics.
Orbital stability for polytropic galaxies
Authors: Sánchez Óscar , Soler Juan
Published: September 2006

In this paper, motivated by the Galilean invariance of the solutions, we use the concept of orbital stability for the Vlasov–Poisson system. We prove that a family of stationary solutions, called polytropic gas spheres, are orbitally

L^{1}

stable in the gravitational case by considering direct variational arguments.

Dans cet article, motivés pour la propriété d'invariance Galiléenne des solutions, nous étudions la notion de stabilité orbitale pour le système de Vlasov–Poisson. Nous obtenons pour le cas gravitationnel que la famille des solutions stationnaires, connue comme gaz de sphères polytropiques, sont orbitalement stables dans

L^{1}

en considérant des arguments variationnels directs.
On the Hénon equation: asymptotic profile of ground states, I
Authors: Byeon Jaeyoung , Wang Zhi-Qiang
Published: September 2006

This paper is concerned with the qualitative property of the ground state solutions for the Hénon equation. By studying a limiting equation on the upper half space

\mathbf{R}_{ + }^{N}

, we investigate the asymptotic energy and the asymptotic profile of the ground states for the Hénon equation. The limiting problem is related to a weighted Sobolev type inequality which we establish in this paper.

Nous nous intéresserons, dans cet article, aux propriétés qualitatives des fonctions minimisantes (ou « ground state solutions ») de l'équation d'Hénon. L'étude d'une équation limite dans le demi-espace supérieur

\mathbf{R}_{ + }^{N}

, nous renseignera sur l'énergie et les caractéristiques limites des fonctions minimisantes de l'équation d'Hénon. Notons que le problème limite est en relation avec une inégalité de Sobolev pondérée que nous établirons également.
Mechanism of hypoxia‐specific cytotoxicity of procaspase‐3 fused with a VHL‐mediated protein destruction motif of HIF‐1α containing Pro564
Authors: Harada Hiroshi , Kizaka-Kondoh Shinae , Hiraoka Masahiro
Published: September 2006

Under normoxic conditions the alpha‐subunit of hypoxia‐inducible factor (HIF‐1α) protein is targeted for degradation by the von Hippel‐Lindau (VHL) tumor suppressor protein acting as an E3 ubiquitin ligase. Recently, we developed a hypoxia‐targeting protein, TOP3, which consisted of procaspase‐3 with the VHL‐mediated protein destruction motif of HIF‐1α. This design enables procaspase‐3 to be regulated similarly with HIF‐1α, being degraded under normoxia while stabilized under hypoxia. Furthermore, stabilized TOP3 was cleaved by the hypoxic stress‐induced endogenous caspases and thus the procaspase‐3 was converted to active caspase‐3 specifically under hypoxic conditions. These data demonstrated that the VHL‐mediated protein destruction motif of HIF‐1α endowed procaspase‐3 with hypoxia‐specific cytotoxicity.
Synthesis of bisphosphonate derivatives of ATP by T4 RNA ligase
Authors: Sillero María A. Günther , de Diego Anabel , Silles Eduardo , Pérez-Zúñiga Francisco , Sillero Antonio
Published: September 2006

T4 RNA ligase catalyzes the synthesis of ATP β,γ‐bisphosphonate analogues, using the following substrates with the relative velocity rates indicated between brackets: methylenebisphosphonate (pCH2p) (100), clodronate (pCCl2p) (52), and etidronate (pC(OH)(CH3)p) (4). The presence of pyrophosphatase about doubled the rate of these syntheses. Pamidronate (pC(OH)(CH2–CH2–NH2)p), and alendronate (pC(OH)(CH2–CH2–CH2–NH2)p) were not substrates of the reaction. Clodronate displaced the AMP moiety of the complex E‐AMP in a concentration dependent manner. The K
m values and the rate of synthesis (k
cat) determined for the bisphosphonates as substrates of the reaction were, respectively: methylenebisphosphonate, 0.26 ± 0.05 mM (0.28 ± 0.05 s−1); clodronate, 0.54 ± 0.14 mM (0.29 ± 0.05 s−1); and etidronate, 4.3 ± 0.5 mM (0.028 ± 0.013 s−1). In the presence of GTP, and ATP or AppCCl2p the relative rate of synthesis of adenosine 5′,5‴‐P1,P4‐tetraphosphoguanosine (Ap4G) was around 100% and 33%, respectively; the methylenebisphosphonate derivative of ATP (AppCH2p) was a very poor substrate for the synthesis of Ap4G. To our knowledge this report describes, for the first time, the synthesis of ATP β,γ‐bisphosphonate analogues by an enzyme different to the classically considered aminoacyl‐tRNA synthetases.
A single amino acid mutation attenuates rundown of voltage‐gated calcium channels
Authors: Zhen Xiao-Guang , Xie Cheng , Yamada Yoichi , Zhang Yun , Doyle Christina , Yang Jian
Published: September 2006

The activity of voltage‐gated calcium channels (VGCCs) decreases with time in whole‐cell and inside‐out patch‐clamp recordings. In this study we found that substituting a single amino acid (I1520) at the intracellular end of IIIS6 in the α1 subunit of P/Q‐type Ca2+ channels with histidine or aspartate greatly attenuated channel rundown in inside‐out patch‐clamp recordings. The homologous mutations also slowed rundown of N‐ and L‐type Ca2+ channels, albeit to a lesser degree. In P/Q‐type channels, the attenuation of rundown is accompanied by an increased apparent affinity for phosphatidylinositol‐4,5‐bisphosphate, which has been shown to be critical for maintaining Ca2+ channel activity [L. Wu, C.S. Bauer, X.‐G. Zhen, C. Xie, J. Yang, Dual regulation of voltage‐gated calcium channels by PtdIns(4,5)P2. Nature 419 (2002) 947–952]. Furthermore, the histidine mutation significantly stabilized the open state, making the channels easier to open, slower to close, harder to inactivate and faster to recover from inactivation. Our finding that mutation of a single amino acid can greatly attenuate rundown provides an easy and efficient way to slow the rundown of VGCCs, facilitating functional studies that require direct access to the cytoplasmic side of the channel.
Transcriptome changes in a colon adenocarcinoma cell line in response to photochemical treatment as used in photochemical internalisation (PCI)
Authors: Prasmickaite Lina , Cekaite Lina , Hellum Marit , Hovig Eivind , Høgset Anders , Berg Kristian
Published: September 2006

The photochemical internalisation (PCI) technology liberates endocytosed macromolecules like transgenes from endocytic vesicles in response to photochemical treatment. Thereby PCI improves gene transfection and is suggested for use in gene therapy. It has been proposed that PCI might also stimulate transcription of internalised transgenes, especially if they are controlled by photochemically inducible promoters (transcriptional targeting). In order to identify inducible promoters, and to evaluate the treatments influence on cellular transcriptional activity, the effect of the photochemical treatment as used in PCI (with the photosensitizer disulfonated meso‐tetraphenylporphin followed by illumination) on gene transcription in WiDr adenocarcinoma cells was evaluated using microarrays. The expression of 390 genes were identified significantly changed (89% were up‐regulated), of which genes associated with DNA binding and transcriptional functions were the most represented. This may be important for the expression of a photochemically internalised transgene under a specific promoter control. Real‐time PCR verified photochemical up‐regulation of the HSP family genes, as well as down‐regulation of EGR‐1 at 2–10 h post‐treatment, suggesting that the HSP (particularly HSP70), in addition to the microarray‐identified metallothioneins, but not the EGR‐1 promoters, could be relevant promoter candidates for transcriptional targeting via PCI. The resulting overview of gene expression changes in WiDr cells exposed to the PCI‐relevant photochemical treatment also provide a basis for the design of new PCI‐based strategies with respect of transcriptional targeting.
Molecular characterization of the hypothetical 66.3‐kDa protein in mouse: Lysosomal targeting, glycosylation, processing and tissue distribution
Authors: Deuschl Florian , Kollmann Katrin , von Figura Kurt , Lübke Torben
Published: September 2006

Recently, we and others identified the 66.3‐kDa protein as one of several putative novel lysosomal matrix proteins by analyzing mannose 6‐phosphate receptors binding proteins [Kollmann K., Mutenda K.E., Balleininger M., Eckermann E., von Figura K., Schmidt B., Lübke T. (2005) Identification of novel lysosomal matrix proteins by proteome analysis. Proteomics 5(15), 3966–3678, Sleat D.E., Lackland H., Wang Y., Sohar I., Xiao G., Li H., Lobel P. (2005) The human brain mannose 6‐phosphate glycoproteome: a complex mixture composed of multiple isoforms of many soluble lysosomal proteins. Proteomics. 5(6), 1520–1532]. Here, we describe the expression of the mouse 66.3‐kDa protein in HT1080 cells in which it is synthesized as a precursor of about 75 kDa and subsequently processed by limited proteolysis to mature polypeptides accumulating in the lysosomal compartment. The lysosomal localisation of the endogenous 66.3‐kDa protein was verified by indirect immunofluorescence in mouse embryonic fibroblasts and by subcellular fractionation of tyloxapol‐filled mouse liver lysosomes. Northern blot analysis reveals high transcriptional levels in testis, liver and kidney, whereas Western blot analysis shows high protein levels in brain, heart, lung and spleen. Interestingly, in mouse the endogenous 66.3‐kDa protein is processed in a highly tissue‐dependent manner to mature forms.
Jellyfish and other cnidarian envenomations cause pain by affecting TRPV1 channels
Authors: Cuypers Eva , Yanagihara Angel , Karlsson Evert , Tytgat Jan
Published: September 2006

Cnidarian envenomations cause a burning‐pain sensation of which the underlying mechanisms are unknown. Activation of TRPV1, a non‐selective cation channel expressed in nociceptive neurons, leads to cell depolarisation and pain. Here, we show in vitro and in vivo evidence for desensitization‐dependent TRPV1 activation in cnidarian envenomations. Cnidarian venom induced a nociceptive reactivity, comparable to capsaicin, in laboratory rats, which could be reduced by the selective TRPV1 antagonist, BCTC. These findings are the first to explain at least part of the symptomology of cnidarian envenomations and provide insights into the design of more effective treatments for this global public health problem.
Palaeolimnology of Lake Zeribar, Iran, and its Climatic Implications
Authors: Wasylikowa Krystyna , Witkowski Andrzej , Walanus Adam , Hutorowicz Andrzej , Alexandrowicz Stefan W. , Langer Jerzy J.
Published: September 2006

Lake Zeribar sediments covering the time period of the last 25,000 years were examined for the contents of seeds, fruits, Characeae, diatoms, and molluscs. Reconstructions of the variations in the lake water level, salinity, and trophy suggest a sequence of climatic changes. Three pronounced stages of low and varying lake-water level occurred ca. 17,700–15,400, 12,600–12,000, and 10,000–6000 cal yr BP. Some water-level changes were correlated with variations in salinity. The most pronounced increase of salinity occurred 17,700–15,700 and 12,600–12,000 cal yr BP, and less distinct ones occurred about 6400–5900 and 2500 cal yr BP. Diatom assemblages indicated a strong increase of lake trophy ca. 20,200 cal yr BP. Between 6000 and 5000 cal yr BP diatoms characteristic of eutrophy increased in core 63J, and at about 3200 cal yr BP a distinct increase in mesotrophic forms occurred in core 70B. The changes in the occurrence of various organisms indicate increased temperatures about 21,000 cal yr BP, between 15,400 and 12,600, about 12,000, and about 11,700 cal yr BP. The reduced occurrence or disappearance of some of them suggest temperature decreases about 17,700–15,400 and 12,600–12,000 cal yr BP.
Timing of Atmospheric Precipitation in the Zagros Mountains Inferred from a Multi-Proxy Record from Lake Mirabad, Iran
Authors: Stevens Lora R. , Ito Emi , Schwalb Antje , Wright Herbert E.
Published: September 2006

A sediment core 7.2 m long from Lake Mirabad, Iran, was examined for loss-on-ignition, mineralogy, oxygen-isotopic composition of authigenic calcite, and trace-element composition of ostracodes to complement earlier pollen and ostracode-assemblage studies. Pollen, ostracode-inferred lake level, and high Sr/Ca ratios indicate that the early Holocene (10000 to 6500 cal yr BP) was drier than the late Holocene. Low δ18O values during this interval are interpreted as resulting from winter-dominated precipitation, characteristic of a Mediterranean climate. Increasing δ18O values after 6500 cal yr BP signal a gradual increase in spring rains, which are present today. A severe 600-yr drought occurred at ca. 5500 cal yr BP, shortly after the transition from pistachio-almond to oak forest. During the late Holocene, two milder droughts occurred at about 1500 and 500 cal yr BP. Within the resolution of the record, no drought is evident during the collapse of the Akkadian empire (4200–3900 cal yr BP). Rather, a decrease in δ18O values to early-Holocene levels may indicate the return to a Mediterranean precipitation regime.
CROP PRODUCTIVITY AND LAND-USE EFFICIENCY OF A TEFF/FABA BEAN MIXED CROPPING SYSTEM IN A TROPICAL HIGHLAND ENVIRONMENT
Authors: AGEGNEHU GETACHEW , GHIZAW AMARE , SINEBO WOLDEYESUS
Published: September 2006

Mixed cropping of teff (Eragrostis tef) with faba bean (Vicia faba) was compared with sole cropping in the 2002 and 2003 growing seasons at Holetta Research Centre, in the central highlands of Ethiopia. The treatments were sole teff (25 kg seed ha−1), sole faba bean (200 kg seed ha−1) and 12.5, 25, 37.5, 50 and 62.5 % of the sole seed rate of faba bean mixed with a full teff seed rate. A randomized complete block design replicated four times was used. Treatment effects were significant for seed and biomass yields of each crop species. Increasing the seed rate of faba bean in teff/faba bean mixture increased faba bean seed yield but decreased teff grain yield. Nonetheless, mixed cropping of faba bean with teff increased land use efficiency and gave higher total yields compared to growing either species in sole culture. Teff yield equivalent, land equivalent ratios (LERs) and system productivity index (SPI) of the mixtures exceeded those of sole crops especially when the seed rate of faba bean in the mixture was increased to 50 kg ha−1 (25 %) or more. The relatively high crowding coefficient values indicated yield advantages from mixed cropping of the two species. The highest values of teff yield equivalent, LER and SPI were obtained when faba bean was mixed at a rate of 62.5 % with the full seed rate of teff. We suggest that, at the current prices of the respective crops, up to 62.5 % of faba bean can be mixed in normal teff to get better total yield and income than sole culture of either species.
Intracranial angiosarcoma arising from a schwannoma
Authors: Ito T , Tsutsumi T , Ohno K , Takizawa T , Kitamura K
Published: September 2006

Angiosarcomas rarely arise from schwannomas, but we describe here a case of angiosarcoma that arose from a remnant of a benign vestibular schwannoma that had been removed 10 years earlier. The patient was a 66-year-old man with no sign of neurofibromatosis. Although we attempted surgical resection, we could not totally remove the tumour. The patient died nine months after diagnosis, primarily as result of an abscess in the cerebellum and base of the skull. The histological diagnosis was confirmed by the immunohistochemical findings of positivity for CD34 antigen and S-100 protein in the resected tumour.

A review of the literature revealed four other cases of angiosarcoma with schwannoma, all of which arose from an extracranial nerve. The present case is the first report of an angiosarcoma with schwannoma arising from an intracranial locus.
A general circulation model study of the orographic gravity waves over Antarctica excited by katabatic winds
Authors: Watanabe Shingo , Sato Kaoru , Takahashi Masaaki
Published: September 2006

In this study, we simulated orographic gravity waves (OGWs) over Antarctica using a T213L250 general circulation model (GCM). The GCM has a fine vertical resolution of 300 m throughout the middle atmosphere. The simulation was run for a 1‐year period. Results from 21–28 June were primarily considered. OGWs are excited by katabatic winds that travel down the surface slopes of the Antarctic ice sheet. A strong eastward katabatic wind blows over the west coast of the Ross Sea at the approach of the synoptic‐scale upper tropospheric westerly jets. A quasi‐stationary OGW is then excited above the coast and propagates upward into the mesosphere. An OGW appears sporadically during the Antarctic winter and spring. Its amplitude is determined by the strength of the eastward katabatic wind. Dissipation of OGWs within the middle atmosphere results in a localized deceleration of westerly winds, greater than −30 m s−1 d−1. This in turn modifies the horizontal circulation in the polar vortex. Strong vertical mixing occurs within the mesosphere and is associated with wave breaking. Large temperature fluctuations associated with the OGWs affect the formation or suppression of polar stratospheric clouds in the lower stratosphere. Katabatic wind excitation is the most powerful source of gravity waves over Antarctica around the time of the winter solstice.
Optimal design of measures to correct seawater intrusion
Authors: Abarca Elena , Vázquez‐Suñé Enric , Carrera Jesús , Capino Bernardo , Gámez Desiré , Batlle Francisco
Published: September 2006

Numerous studies have been devoted to the optimization of groundwater management strategies in coastal aquifers. However, little has been done to address the problem of initially contaminated aquifers, the subject of this paper. Corrective measures need to be optimally designed to improve water quality while minimizing changes in the existing pumping regime. To this end, we compare two optimization methods. The first one is linear and consists of maximizing pumping rates while constraining heads to prevent seawater inflow. The second one consists of minimizing the changes from current pumping rates, so as to preserve existing rights, while constraining concentrations, which leads to a nonlinear programming problem. In both cases, corrective measures include a reduction in pumping rates, inland artificial recharge, and a coastal hydraulic barrier. Not surprisingly, the nonlinear problem leads to a more efficient solution, both in terms of pumping rates and actual cleanup of the aquifer. Nevertheless, the linear formulation yields insights into the optimal allocation of pumping. More importantly, the linear formulation enables us to readily calculate the hydraulic efficiency (gain in pumping rate per unit increase in recharge rate) of corrective measures. The fact that efficiency is consistently greater than 1 proves that the hydraulic barrier not only increases resources but also protects the existing ones. Therefore we conclude that both optimization approaches are useful and should be used.
A simple scale height model of the electron density in Saturn's plasma disk
Authors: Persoon A. M. , Gurnett D. A. , Kurth W. S. , Groene J. B.
Published: September 2006

A study of electron densities in Saturn's inner magnetosphere is presented using measurements of the upper hybrid resonance frequency obtained from the Radio and Plasma Wave Science (RPWS) instrument on the Cassini spacecraft. The study uses data from the first 16 months of operation in orbit around Saturn. The distribution of density data spans latitudes up to 20° and ranges from 3.6 ≤ L ≤ 8.6. The results are compared to a simple centrifugal potential model for the plasma density. The measurements for 5 ≤ L ≤ 8.6 yield a good fit to an equatorial electron density profile that varies as n0 = (51,880) L−4.1 cm−3 and a plasma scale height that varies as H = (0.047) L1.8 RS, where RS is the radius of Saturn. The measurements for L < 5 are more variable, most likely due to plasma injection effects by Saturn's moon Enceladus which is a known source of neutral gas. A contour map of the electron densities derived from the centrifugal potential model is presented over the entire range of L values and latitudes analyzed, using cubic polynomials to represent the radial profiles of the equatorial electron density and the plasma scale height.
Mapping sub‐pixel surface roughness on Mars using high‐resolution satellite image data
Authors: Mushkin Amit , Gillespie Alan R.
Published: September 2006

The ratio between co‐registered pixels in stereo or repeat image pairs is used to constrain the deviation of the Martian surface from Lambertian reflection due to unresolved shadows at the pixel scale of orbiting imagers. Relative differences between the ratios primarily reflect differences in the effective amount of shadows ‘seen’ by the sensor in the two measurements, and are thus used as a relative proxy for sub‐pixel surface roughness (SR). In‐scene atmospheric corrections enable simple application of this ‘two‐look’ approach, which facilitates robust SR mapping at spatial resolutions comparable to the image data. Relative ‘two‐look’ SR estimates can be translated to physical SR parameters through empirical calibration using ground‐based measurements. SR variation maps in Gusev crater were derived from THEMIS and HRSC images at 18‐ and 30‐ m/pixel, respectively. The latter were calibrated using measurements from Spirit to produce a quantitative clast‐coverage map of Spirit's initial traverse in Gusev crater.
An experimental analogue for convection and phase separation in hydrothermal systems
Authors: Emmanuel Simon , Berkowitz Brian
Published: September 2006

Experiments were conducted to explore the behavior of convection and heat transfer during phase separation in porous media. Phase separation is considered to be an important process in many mid‐ocean ridge hydrothermal systems in which a dense brine separates from a lighter, less saline vapor phase at supercritical temperatures. As this process occurs at high temperatures and pressures in seawater systems, a binary fluid (H2O‐2‐butoxyethanol) with a lower consolute point of 48.5°C, was used as a proxy for the hydrothermal fluid. In the experiments, a cell containing glass beads saturated with the binary fluid was heated from below and cooled from above. It was demonstrated that chemically differentiated regions can exist as part of a steady state convective regime, with the denser fluid phase separating and accumulating in a stagnant bottom layer. Furthermore, in upwelling regions phase separating fluids can become entrained. Phase separation was also found to lower the efficiency of convective thermal transfer, indicated by the deviation from the calculated single‐phase Rayleigh‐Nusselt curve. It is proposed that the reduction of convective heat transfer at supercritical conditions may be a crucial factor in controlling heat transfer through the oceanic crust.
High sensitivity beam emission spectroscopy for core plasma turbulence imaging (invited)
Authors: McKee G. R. , Fonck R. J. , Gupta D. K. , Schlossberg D. J. , Shafer M. W. , Boivin R. L.
Published: September 2006

An upgraded beam emission spectroscopy (BES) diagnostic has been developed and deployed at the DIII-D tokamak to achieve a dramatic increase in sensitivity to small-scale density fluctuations. This upgraded BES diagnostic system incorporates high-throughput silica optical fiber bundles (1.62mm2-ster per channel), ultra fast spectrometer collection optics, custom-designed high-transmission interference filters, and large-area photodiodes. The fiber bundle images are optimized to match measured radial and poloidal asymmetries of turbulent eddies. These enhancements result in an approximately one order of magnitude increase in measured beam emission signal. As a consequence of the relative contributions of photon and electronic noise, the net increase in sensitivity to plasma density fluctuation power ranges from ten to 30, allowing for the observation of small-amplitude (ñ∕n⩾0.1%) density fluctuations associated with turbulence and energetic particle modes in the core of high-performance discharges. An array of 16 BES channels has been arranged in a 4×4 grid to provide modest-field (3.2×5cm), high-sensitivity imaging capability that extends over multiple turbulence correlation lengths. This diagnostic capability allows for the first direct imaging of turbulence in the core region of low-confinement and high-confinement tokamak plasmas.
Motional Stark effect diagnostic pilot experiment for MAST
Authors: Kuldkepp M. , Walsh M. J. , Carolan P. G. , Conway N. J. , Hawkes N. C. , McCone J. , Rachlew E. , Wearing G.
Published: September 2006

Exploiting the motional Stark effect (MSE) in the low magnetic fields of spherical tokamaks such as MAST is complicated by the Doppler smearing of the relatively closely spaced Stark components. Extensive modeling of MSE spectra and the subsequent polarized fraction (∼20%) of spectrally filtered light and signal to noice ratios have been performed taking account of real experimental conditions including neutral beam parameters, port sizes, optical losses, filter characteristics, etc. A design is selected which uses high throughput interference filters (0.1nm bandpass) for separation of the spectral components. An accuracy of ∼0.5° compared with typically 15° is estimated for field angle measurements. The design allows for early implementation, starting with a pilot two chord system, and for an economic expansion to a multiplicity of chords. Matching the Doppler shifted Dα from the beam neutrals will be accomplished by a combination of filter selection and fine-tuning of the beam voltage. Avoiding filter tuning in the design greatly simplifies the diagnostic. Calibration results of the diagnostic support the calculations.
Enhanced core charge exchange recombination spectroscopy system on Joint European Torus
Authors: Negus C. R. , Giroud C. , Meigs A. G. , Zastrow K.-D. , Hillis D. L. ,   JET-EFDA Contributors
Published: September 2006

Charge exchange spectroscopy is a key diagnostic on the Joint European Torus for radial profiles of ion temperature, toroidal rotation, and impurity densities. This article describes the current status and the improvements made over the last five years. The current system consists of two periscopes looking at one of the two banks of neutral heating beams, ≈90 optical fibers defining viewing directions, and seven spectrometers with charge-coupled device (CCD) cameras. The upgrade has involved replacement of the two periscopes and windows, a doubling of the number of optical fibers (plasma viewing directions), new cameras for the existing spectrometers, improvements to the throughput and long-term stability of the five existing spectrometers, and the addition of two new high-throughput spectrometers with their CCD cameras from ORNL. This work has culminated in improved spatial resolution, increased sensitivity of all the plasma viewing channels (for some by a factor of ∼3 or more), and enhanced time resolution from 50 to around 10 ms.
Electron density fluctuation measurements using a multichannel microwave interferometer in GAMMA 10
Authors: Yoshikawa M. , Shima Y. , Matsumoto T. , Nakahara A. , Yanagi N. , Itakura A. , Hojo H. , Kobayashi T. , Matama K. , Tatematsu Y. , Imai T. , Kohagura J. , Hirata M. , Nakashima Y. , Cho T.
Published: September 2006

Measurement of fluctuation in plasma is important for studying the improvement in plasma confinement by the formation of the plasma confinement potential. The density fluctuation is observed by microwaves by methods such as interferometry, reflectometry and Fraunhofer diffraction method. We have constructed a new multichannel microwave interferometer to measure the plasma density and fluctuation radial profiles in a single plasma shot. We successfully measured the time-dependent density and line-integrated density fluctuation radial profiles in a single plasma shot using the multichannel microwave interferometer. Thus, we have developed a useful tool for studying the improvement in plasma confinement by the formation of plasma confinement potential.
A parametric variant of resonant activation: Two-state model approach
Authors: Ghosh Pulak Kumar , Ray Deb Shankar
Published: September 2006

Mean first passage time of a periodically driven particle for its escape over a fluctuating barrier with wells remaining unbiased exhibits a resonance when the frequency of the driving field is varied. This parametric variant of resonant activation and associated features of noise induced transition are realized in terms of a two-state model to estimate analytically several quantifiers of the escape event. Numerical simulation on a continuous double-well model collaborates our theoretical analysis.
On-ground characterization of Rosetta/VIRTIS-M. I. Spectral and geometrical calibrations
Authors: Ammannito E. , Filacchione G. , Coradini A. , Capaccioni F. , Piccioni G. , De Sanctis M. C. , Dami M. , Barbis A.
Published: September 2006

The complete characterization of complex imaging spectrometers, such as VIRTIS-M (visual infrared thermal imaging spectrometer) aboard the Rosetta mission, requires a detailed and prolonged activity starting with the instrument integration and continuing during the entire operational life of the experiment. In this article we report the main experimental activities realized during the on-ground characterizations to evaluate the spectral and geometric performances in order to check the conformance with the technical requirements derived from the scientific goals of the experiment. Spectral calibrations allow to confirm instrumental spectral range, resolution, and sampling; geometric calibrations are necessary to estimate the pixel and slit functions, field of view extension, and possible optical aberrations. Two separate sections are dedicated to each one of these subjects, including the strategy followed to prepare measurements, a basic description of the on-ground experimental setups, and the analysis of the collected data.
Transition from multiple to single microcontact conduction during hot switching of microelectromechanical switches with ball-shaped dimples
Authors: Chow Linda L. W. , Schrader Steven A. , Kurabayashi Katsuo
Published: September 2006

Previous studies of electron transport within direct contact microelectromechanical switches have found that conduction occurs via nanoscale contact asperities. It has been claimed that reduced contact resistance can be achieved by using multiple contact switches; however, the ability of these switches to enhance power handling or lifetime remains a question. To study the contact mechanism, single-input-multiple-output switches with ball-shaped dimples were specially designed and tested. At all voltage levels of hot-switching operation, uneven current sharing among the outputs was observed. Furthermore, at softening voltage, an irreversible multiple to single conduction transition occurs and is found to alternate among different outputs.
Optogalvanic effect and measurement of gas temperature in an abnormal glow discharge
Authors: Obradović Bratislav M. , Kuraica Milorad M.
Published: September 2006

Axial distribution of the gas temperature in an abnormal glow discharge in argon is simultaneously determined by laser optogalvanic and absorption spectroscopy methods. Temperature distributions obtained by two different methods are in a fair agreement except in the boundary region between the cathode fall and the negative glow. Systematically lower temperature in this region obtained by optogalvanic spectroscopy is a consequence of the nature of optogalvanic effect, which, in some circumstances, cannot be identified with spectral line profile.
Three-dimensional potential energy surface of the Ar–OH(Πi2) complex
Authors: Sumiyoshi Yoshihiro , Funahara Ippei , Sato Kazuya , Ohshima Yasuhiro , Endo Yasuki
Published: September 2006

Pure rotational transitions in the ground state for Ar–OH and Ar–OD [Y. Ohshima et al., J. Chem. Phys. 95, 7001 (1991) and Y. Endo et al., Faraday Discuss. 97, 341 (1994)], those in the excited states of the OH vibration, νs=1 and 2, observed by Fourier-transform microwave spectroscopy in the present study, rotation-vibration transitions observed by infrared-ultraviolet double-resonance spectroscopy [K. M. Beck et al., Chem. Phys. Lett. 162, 203 (1989) and R. T. Bonn et al., J. Chem. Phys. 112, 4942 (2000)], and the P-level structure observed by stimulated emission pumping spectroscopy [M. T. Berry et al., Chem. Phys. Lett. 178, 301 (1991)] have been simultaneously analyzed to determine the potential energy surface of Ar–OH in the ground state. A Schrödinger equation, considering all the freedom of motions for an atom-diatom system in the Jacobi coordinate, R, θ, and r, was numerically solved to obtain energies of the rovibrational energy levels using the discrete variable representation method. A three-dimensional potential energy surface is determined by a least-squares fitting. In the analysis the potential parameters, obtained by ab initio calculations at the RCCSD(T) level of theory with a set of basis functions of aug-cc-pVTZ and midbond functions, are used as initial values. The determined intermolecular potential energy surface and its dependence on the OH monomer bond length are compared with those of an isovalent radical complex, Ar–SH.
Rotranslational state-to-state rates and spectral representation of inelastic collisions in low-temperature molecular hydrogen
Authors: Montero S. , Thibault F. , Tejeda G. , Fernández J. M.
Published: September 2006

Inelastic collisions in natural H2 are studied from the experimental and theoretical points of view between 10 and 140K. Rotational populations and number densities measured by Raman spectroscopy along supersonic expansions of H2 provide the link between experimental and theoretical rotranslational state-to-state rate coefficients of H2 in the vibrational ground state. These rates are calculated in the close- scattering approach with the MOLSCAT code employing a recent ab initio H2–H2 potential. The calculated rates are assessed by means of a master equation describing the time evolution of the experimental rotational populations. The feasibility for obtaining the rates on the sole basis of the experiment is discussed. The dominant processes j1j2→j1′j2′ in the investigated thermal range are found to be 21→01>30→12>31→11, proving the importance of double processes such as 30→12. Good agreement is found between theory and experiment, as well as with earlier ultrasonic measurements of relaxation times. A spectral representation is proposed in order to visualize quantitatively the collisional contributions in any nonequilibrium time evolving process.
Simulation of symmetric tricritical behavior in electrolytes
Authors: Ren Ruichao , O’Keeffe C. J. , Orkoulas G.
Published: September 2006

Despite extensive experimental, theoretical, and simulation efforts, a unified description of ionic phase transitions and criticality has not yet emerged. In this work, we investigate the phase behavior of the restricted primitive model of electrolyte solutions on the simple cubic lattice using grand canonical Monte Carlo simulations and finite-size scaling techniques. The phase diagram of the system is distinctly different from its continuum-space analog. We find order-disorder transitions for reduced temperatures T*≲0.51, where the ordered structures resemble those of the NaCl crystal. The order-disorder transition is continuous for 0.15≲T*≲0.51 and becomes first order at lower temperatures. The line of first-order transitions is a line of three-phase coexistence between a disordered and two ordered phases. The line of continuous, second-order transitions meets this line of triple points at a tricritical point at T*≃0.1475. We locate the line of continuous transitions, and the line of triple points using finite-size scaling techniques. The tricritical temperature is estimated by extrapolation of the size-dependent tricritical temperatures obtained from a sixth-order Landau expansion of the free energy. Our calculated phase diagram is in qualitative agreement with mean-field theories.
Effect of donor-acceptor interaction strength on excitation energy migration and diffusion at high donor concentrations
Authors: Tripathy Umakanta , Bisht Prem B.
Published: September 2006

The migration and diffusion modulated excitation energy transfer has been studied in a new dye pair 7-diethylamino-4-methylcoumarin (donor) to 3,3′-dimethyloxacarbocyanine iodide (acceptor) by steady-state and picosecond time-resolved spectroscopy. To reduce the artifact of self-absorption, at high donor concentrations, the time-resolved studies have been carried out in thin films of polyvinyl alcohol (solid matrix) and in methanol (liquid phase) at front-face geometry of excitation. The Förster-type (nonradiative) energy transfer [Discuss. Faraday Soc. 27, 7 (1959)] takes place directly from donor to acceptor in case of solid matrix, while Yokota-Tanimoto model [J. Phys. Soc. Jpn. 22, 779 (1967)] for diffusion has been found to be operating in the liquid phase. It has been found here that the high interaction strength between donor and acceptor molecules as compared to that among donors masks the effect of energy migration and diffusion at high donor concentrations. The rate and efficiency of energy transfer increase with increasing the acceptor concentration. This has been confirmed by the study of acceptor kinetics.
Langevin dynamics simulations of polymer translocation through nanopores
Authors: Huopaniemi Ilkka , Luo Kaifu , Ala-Nissila Tapio , Ying See-Chen
Published: September 2006

We investigate the dynamics of polymer translocation through a nanopore using two-dimensional Langevin dynamics simulations. In the absence of an external driving force, we consider a polymer which is initially placed in the middle of the pore and study the escape time τe required for the polymer to completely exit the pore on either side. The distribution of the escape times is wide and has a long tail. We find that τe scales with the chain length N as τe∼N1+2ν, where ν is the Flory exponent. For driven translocation, we concentrate on the influence of the friction coefficient ξ, the driving force E, and the length of the chain N on the translocation time τ, which is defined as the time duration between the first monomer entering the pore and the last monomer leaving the pore. For strong driving forces, the distribution of translocation times is symmetric and narrow without a long tail and τ∼E−1. The influence of ξ depends on the ratio between the driving and frictional forces. For intermediate ξ, we find a crossover scaling for τ with N from τ∼N2ν for relatively short chains to τ∼N1+ν for longer chains. However, for higher ξ, only τ∼N1+ν is observed even for short chains, and there is no crossover behavior. This result can be explained by the fact that increasing ξ increases the Rouse relaxation time of the chain, in which case even relatively short chains have no time to relax during translocation. Our results are in good agreement with previous simulations based on the fluctuating bond lattice model of polymers at intermediate friction values, but reveal additional features of dependency on friction.
Structural anomalies for a three dimensional isotropic core-softened potential
Authors: de Oliveira Alan Barros , Netz Paulo A. , Colla Thiago , Barbosa Marcia C.
Published: September 2006

Using molecular dynamics simulations we investigate the structure of a system of particles interacting through a continuous core-softened interparticle potential. We found for the translational order parameter t a local maximum at a density ρt-max and a local minimum at ρt-min>ρt-max. Between ρt-max and ρt-min, the t parameter anomalously decreases upon increasing pressure. For the orientational order parameter Q6 a maximum was observed at a density ρt-max<ρQmax<ρt-min. For densities between ρQmax and ρt-min, both the translational (t) and orientational (Q6) order parameters have anomalous behavior. We know that this system also exhibits density and diffusion anomalies. We found that the region in the pressure-temperature phase diagram of the structural anomaly englobes the region of the diffusion anomaly that is larger than the region limited by the temperature of maximum density. This cascade of anomalies (structural, dynamic, and thermodynamic) for our model has the same hierarchy as that observed for the simple point charge/extended water.
Apparent mismatch between extended x-ray absorption fine structure and diffraction structures of crystalline metastable WO3 phases
Authors: Moscovici J. , Rougier A. , Laruelle S. , Michalowicz A.
Published: September 2006

The local structure of monoclinic, monohydrate, hexagonal, and pyrochlore WO3 phases was investigated by the extended x-ray absorption fine structure spectroscopy as preliminary studies of model compounds of amorphous and thin film WO3 based electrochromic species. In the four cases, we found a large W–O distribution of distances ranging from 1.70to2.35Å. The apparent discrepancy of these results and previously published crystal structures are discussed and interpreted as the detection of vacancies and local distortion disorder.