bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluating the Effort Expended to Understand Speech in Noise Using a Dual-Task Paradigm: The Effects of Providing Visual Speech Cues
Authors: Fraser Sarah , Gagné Jean-Pierre , Alepins Majolaine , Dubois Pascale
Published: July 2009

Purpose

Using a dual-task paradigm, 2 experiments (Experiments 1 and 2) were conducted to assess differences in the amount of listening effort expended to understand speech in noise in audiovisual (AV) and audio-only (A-only) modalities. Experiment 1 had equivalent noise levels in both modalities, and Experiment 2 equated speech recognition performance levels by increasing the noise in the AV versus A-only modality.

Method

Sixty adults were randomly assigned to Experiment 1 or Experiment 2. Participants performed speech and tactile recognition tasks separately (single task) and concurrently (dual task). The speech tasks were performed in both modalities. Accuracy and reaction time data were collected as well as ratings of perceived accuracy and effort.

Results

In Experiment 1, the AV modality speech recognition was rated as less effortful, and accuracy scores were higher than A only. In Experiment 2, reaction times were slower, tactile task performance was poorer, and listening effort increased, in the AV versus the A-only modality.

Conclusions

At equivalent noise levels, speech recognition performance was enhanced and subjectively less effortful in the AV than A-only modality. At equivalent accuracy levels, the dual-task performance decrements (for both tasks) suggest that the noisier AV modality was more effortful than the A-only modality.
Accuracy of Consonant–Vowel Syllables in Young Cochlear Implant Recipients and Hearing Children in the Single-Word Period
Authors: Warner-Czyz Andrea D. , Davis Barbara L. , MacNeilage Peter F.
Published: July 2009

Purpose

Attaining speech accuracy requires that children perceive and attach meanings to vocal output on the basis of production system capacities. Because auditory perception underlies speech accuracy, profiles for children with hearing loss (HL) differ from those of children with normal hearing (NH).

Method

To understand the impact of auditory history on emergence of speech capacities, the authors compared consonant–vowel (CV) syllable accuracy in early words in 4 NH children and 4 children with HL who received cochlear implantation (CI) before age 2 years. Participants were video-recorded monthly for 6 months following word onset. CV vocalizations were coded perceptually with broad phonetic transcription. Observed-to-expected ratios of CV productions and accuracy were tested with chi-square analysis. An ordered multinomial model tested level of accuracy, including both accuracy and error patterns.

Results

Most frequently produced sequences were most accurately produced across group and time. NH children were more accurate overall than children with CI. Both groups improved accuracy over time by decreasing partially accurate productions (accurate consonant–inaccurate vowel). Both groups favored CV patterns with compatible place of articulation between consonant and vowel in absolute frequency and level of accuracy.

Conclusion

Differences in emergence of CV syllable accuracy arise from differences in auditory perception between the NH and CI groups.
Investigation of external noise and its rejection in magnetoelectric sensor design
Authors: Xing Zengping , Zhai Junyi , Li Jiefang , Viehland Dwight
Published: July 2009

Laminated magnetoelectric (ME) composites consisting of magnetostrictive and piezoelectric layers are an important class of magnetic sensors. Here, we will present a means to design ME sensors with in-built capabilities to cancel environmental noise, based on designing the sensor signal and the noise in different fundamental modes. We then show that some composite designs offer unique capabilities to reject acoustic or thermal noise sources.
Influence of growth parameters on the perpendicular magnetic anisotropy of [Co/Ni] multilayers and its temperature dependence
Authors: Posth O. , Hassel C. , Spasova M. , Dumpich G. , Lindner J. , Mangin S.
Published: July 2009

[Co/Ni] multilayer films are grown in various conditions to study the influence of growth parameters on the anisotropy of the films in order to optimize the perpendicular uniaxial anisotropy. These multilayers are expected to be useful for current induced magnetization switching experiments due to its softmagnetic behavior by which the critical current density can be reduced dramatically. The polycrystalline films are prepared by electron beam evaporation with varying buffer layer, cap layer, as well as Co layer thickness and number of repetitions of Co and Ni layers. Measurements of the magneto-optic Kerr effect, ferromagnetic resonance, and superconducting quantum interference device magnetometry are used to analyze the magnetic anisotropy and magnetization. Depending on the magnitude of the uniaxial anisotropy, the overall easy direction of magnetization is orientated either in plane or out of plane depending on the amplitude of the demagnetization field. Moreover, we present the results for the temperature dependence of the uniaxial anisotropy and the magnetization of the [Co/Ni] film from 5 up to 420 K, which is close to the Curie temperature.
Broad, intense, quiescent beam of singly charged metal ions obtained by extraction from self-sputtering plasma far above the runaway threshold
Authors: Anders André , Oks Efim
Published: July 2009

Dense metal plasmas obtained by self-sputtering far above the runway threshold are well suited to generate intense quiescent ion beams. The dilemma of high current density and charge state purity can be solved when using target materials of low surface binding energy by utilizing nonresonant exchange reactions before ion extraction. Space-charge-limited quiescent beams of Cu+, Zn+, and Bi+ with ∼10 mA/cm2 have been obtained through multiaperture gridded ion extraction up to 45 kV from self-sputtering plasmas.
Alkali-helium snowball complexes formed on helium nanodroplets
Authors: Müller S. , Mudrich M. , Stienkemeier F.
Published: July 2009

We systematically investigate the formation and stability of snowballs formed by femtosecond photoionization of small alkali clusters bound to helium nanodroplets. For all studied alkali species Ak=(Na,K,Rb,Cs) we observe the formation of snowballs Ak+HeN when multiply doping the droplets. Fragmentation of clusters AkN upon ionization appears to enhance snowball formation. In the case of Na and Cs we also detect snowballs Ak2+HeN formed around Ak dimer ions. While the snowball progression for Na and K is limited to less than 11 helium atoms, the heavier atoms Rb and Cs feature wide distributions at least up to Ak+He41. Characteristic steps in the mass spectra of Cs-doped helium droplets are found at positions consistent with predictions on the closure of the first shell of helium atoms around the Ak+ ion based on variational Monte Carlo simulations.
Enhanced domain contribution to ferroelectric properties in freestanding thick films
Authors: Ryu Jungho , Priya Shashank , Park Chee-Sung , Kim Kun-Young , Choi Jong-Jin , Hahn Byung-Dong , Yoon Woon-Ha , Lee Byoung-Kuk , Park Dong-Soo , Park Chan
Published: July 2009

We report the success in fabricating clamped, “island,” and freestanding 10 μm thick piezoelectric films using aerosol deposition. The deposition was conducted at room temperature by impinging the piezoelectric particles flowing through the nozzle onto platinized silicon (Pt/Ti/SiO2/Si) substrate and crystallization was conducted by annealing at 700 °C. Freestanding films were synthesized by increasing the cooling rate from annealing temperature to room temperature which resulted in large internal stress between the substrate and film interface. Dielectric and ferroelectric characterizations showed enhanced ferroelectric performance of freestanding films as compared to continuous or clamped film which was associated to increased domain contribution due to decrease in degree of clamping as further confirmed by piezoforce microscopy.
Stabilization of very high-k tetragonal phase in Ge-doped ZrO2 films grown by atomic oxygen beam deposition
Authors: Tsoutsou D. , Apostolopoulos G. , Galata S. F. , Tsipas P. , Sotiropoulos A. , Mavrou G. , Panayiotatos Y. , Dimoulas A. , Lagoyannis A. , Karydas A. G. , Kantarelou V. , Harissopoulos S.
Published: July 2009

Ge-doped ZrO2 thin films are prepared on SiON/Si substrates by atomic oxygen beam deposition. It is shown that, at low growth temperatures (225–360 °C) and by using only a low amount of Ge (3–6.2 at. %), it is possible to develop a pure tetragonal zirconia phase, which remains stable after 1050 °C annealing in N2. The dielectric permittivity (k) shows pronounced correlation with the structural details of the oxide film and is increasing with Ge content to a maximum value of 37.7, which is obtained for a 6.2 at. % Ge-doped sample grown at 225 °C. The dielectric permittivity enhancement upon doping is attributed to the increase in the ZrO2 tetragonal distortion, as inferred from x-ray diffraction data. Obtaining tetragonal ZrO2 with very high k-values at low deposition temperatures and with excellent thermal stability could be beneficial for the integration of this dielectric in scaled devices requiring low equivalent oxide thickness.
Changes in the structure of an atomic-layer-deposited HfO2 film on a GaAs (100) substrate as a function of postannealing temperature
Authors: Kim C. Y. , Cho S. W. , Cho M.-H. , Chung K. B. , Suh D. C. , Ko D.-H. , An C.-H. , Kim H. , Lee H. J.
Published: July 2009

The effects of postannealing temperature on the crystal structure and energy band gap (Eg) values of atomic-layer-deposited HfO2 films grown on a GaAs (100) substrate were investigated. In postannealed HfO2 films prepared using a rapid thermal annealing (RTA) process in a N2 ambient at temperatures over 600 °C, the initially produced, partially crystallized HfO2 film changed into a well-ordered crystalline structure with no detectable interfacial layer between the film and the GaAs substrate. In the case of a RTA prepared at 700 °C, the thickness of the film was relatively increased compared to that of an as-grown film. Changes in the depth profile data related to stoichiometry and electronic structure after the annealing treatment indicated that Ga oxide is formed within the HfO2 film during the RTA. The formation of Ga oxide in the film significantly affected the Eg values, i.e., the Eg changed from 5.5 for an as-grown film to 4.7 eV for a film annealed at 700 °C.
Temperature dependence of excitonic properties of (111)B InGaAs/GaAs piezoelectric and pyroelectric multiquantum wells
Authors: Cho Soohaeng , Majerfeld A.
Published: July 2009

We report the comprehensive study on the temperature dependence of excitonic properties for an InGaAs/GaAs p-i-n multiquantum well structure grown on a (111)B GaAs substrate by molecular-beam epitaxy using photoreflectance spectroscopy, in which the pyroelectric effect (temperature dependence of piezoelectric field) is taken into account. The temperature dependence of the confined transition energies was investigated in terms of a Varshni’s semiempirical equation and a Bose–Einstein expression to analyze the excitonic properties. We also determined the optical-phonon energy and strength of electron-phonon coupling for the ⟨111⟩ crystallographic directions of this material system, as well as the interface roughness from an analysis of the temperature dependence of PR broadening parameters.
A relativistic planar diode
Authors: Lindsay P. A. , Li D. , Chen X.
Published: July 2009

Potential and velocity distributions in a relativistic, planar diode are presented in the form of graphs for a range of initial injection velocities. The important stability conditions for distributions with a potential (velocity) minimum are also established.
Nickel-induced crystallization of amorphous Ge film for blue-ray recording under thermal annealing and pulsed laser irradiation
Authors: Her Yung-Chiun , Chen Jyun-Hung , Tsai Ming-Hsin , Tu Wei-Ting
Published: July 2009

The crystallization kinetics of a-Ge thin film induced by a thin Ni layer under thermal annealing and pulsed laser irradiation has been studied. Under thermal annealing, the crystallization temperature and activation energy for crystallization of a-Ge in the a-Ge/Ni bilayer recording film were significantly reduced to 385 °C and 2.4 eV, respectively, due to the fast Ge diffusion in the already formed germanide phases. The reaction exponent m of ∼1.7 for the a-Ge/Ni bilayer corresponds to a crystallization process in which grain growth occurs with nucleation and the nucleation rate decreases with the progress of the grain growth process. Under pulsed laser irradiation, the maximum data-transfer rates of 22, 56, 74, and 112 Mbits/s can be achieved in the write-once blue-ray disk at the recording powers of 3, 4, 5, and 6 mW, respectively.
A versatile ultrastable platform for optical multidimensional Fourier-transform spectroscopy
Authors: Bristow A. D. , Karaiskaj D. , Dai X. , Zhang T. , Carlsson C. , Hagen K. R. , Jimenez R. , Cundiff S. T.
Published: July 2009

The JILA multidimensional optical nonlinear spectrometer (JILA-MONSTR) is a robust, ultrastable platform consisting of nested and folded Michelson interferometers that can be actively phase stabilized. This platform generates a square of identical laser pulses that can be adjusted to have arbitrary time delay between them while maintaining phase stability. The JILA-MONSTR provides output pulses for nonlinear excitation of materials and phase-stabilized reference pulses for heterodyne detection of the induced signal. This arrangement is ideal for performing coherent optical experiments, such as multidimensional Fourier-transform spectroscopy, which records the phase of the nonlinear signal as a function of the time delay between several of the excitation pulses. The resulting multidimensional spectrum is obtained from a Fourier transform. This spectrum can resolve, separate, and isolate coherent contributions to the light-matter interactions associated with electronic excitation at optical frequencies. To show the versatility of the JILA-MONSTR, several demonstrations of two-dimensional Fourier-transform spectroscopy are presented, including an example of a phase-cycling scheme that reduces noise. Also shown is a spectrum that accesses two-quantum coherences, where all excitation pulses require phase locking for detection of the signal.
An improved high intensity recycling helium-3 beam source
Authors: Hedgeland H. , Kole P. R. , Allison W. , Ellis J. , Jardine A. P.
Published: July 2009

We describe an improved high intensity, recycling, supersonic atomic beam source. Changes address several issues previously limiting performance and reliability of the apparatus, including the use of newly available vacuum pumps and modifications to the recycling system. We achieve a source intensity of 2.5×1019 atoms/s/sr, almost twice that previously achievable during recycling. Current limits on intensity are discussed.
High pressure dynamics of polymer/plasticizer mixtures
Authors: Schwartz Gustavo Ariel , Paluch Marian , Alegría Ángel , Colmenero Juan
Published: July 2009

Plasticizers are usually added to polymers to give them the desired flexibility and processability by changing the dynamical properties of the polymer chains. It is therefore important to give a quantitative description about how the dynamic behavior of a given polymer is modified by the incorporation of a second component. We analyze in this work, by means of dielectric spectroscopy, the dynamics of poly(vinyl acetate)/diethyl phthalate mixtures, at different concentrations, over a broad range of frequency, pressure, and temperature. The dynamics of these particular mixtures show only one main relaxation process contrarily to what is observed in athermal miscible polymer mixtures. From the dielectric spectra the maximum relaxation time as a function of pressure and temperature was obtained and analyzed. We studied the pressure dependence of the glass transition temperature as well as the fragility of both the neat components and the mixtures at different concentrations (on the rich polymer range). Finally, the experimental data were rationalized within the framework of an Adam–Gibbs (AG) based approach recently developed [G. A. Schwartz et al., J. Chem. Phys. 127, 154907 (2007)]. The model, originally developed for athermal blends, is here modified to take into account the non-negligible interaction between polymer and plasticizer. We found that the temperature-pressure dependence of the α-relaxation time is very well described by this AG extended model.
High performance AlGaN/GaN power switch with HfO2 insulation
Authors: Shi Junxia , Eastman Lester F. , Xin Xiaobin , Pophristic Milan
Published: July 2009

High performance AlGaN/GaN metal-insulator-semiconductor heterostructure field-effect transistor was fabricated using HfO2 as the surface passivation and gate insulator. The gate and drain leakage currents are drastically reduced to tens of nanoamperes before breakdown. Without field plates, for 10 μm of gate-drain spacing, the off-state breakdown voltage is 1035 V with a specific on resistance of 0.9 mΩ cm2. In addition, there is no current slump observed from the pulse measurements. This is the best performance reported on GaN-based power-switching devices on sapphire up to now, which efficiently combines excellent device forward, reverse, and switching characteristics.
Nanosecond switching in GeTe phase change memory cells
Authors: Bruns G. , Merkelbach P. , Schlockermann C. , Salinga M. , Wuttig M. , Happ T. D. , Philipp J. B. , Kund M.
Published: July 2009

The electrical switching behavior of GeTe-based phase change memory devices is characterized by time resolved experiments. SET pulses with a duration of less than 16 ns are shown to crystallize the material. Depending on the resistance of the RESET state, the minimum SET pulse duration can even be reduced down to 1 ns. This finding is attributed to the increasing impact of crystal growth upon decreasing switchable volume. Using GeTe or materials with similar crystal growth velocities, hence promises nonvolatile phase change memories with dynamic random access memorylike switching speeds.
Composition dependence of photoluminescence of GaAs1−xBix alloys
Authors: Lu Xianfeng , Beaton D. A. , Lewis R. B. , Tiedje T. , Zhang Yong
Published: July 2009

Room temperature photoluminescence (PL) spectra have been measured for GaAs1−xBix alloys with Bi concentrations in the 0.2%–10.6% range. The decrease in the PL peak energy with increasing Bi concentration follows the reduction in bandgap computed from density functional theory. The PL peak energy is found to increase with PL pump intensity, which we attribute to the presence of shallow localized states associated with Bi clusters near the top of the valence band. The PL intensity is found to increase with Bi concentration at low Bi concentrations, peaking at 4.5% Bi.
Tuning colloidal interactions in subcritical solvents by solvophobicity: Explicit versus implicit modeling
Authors: Dzubiella J. , Chakrabarti J. , Löwen H.
Published: July 2009

The distance-resolved effective interaction between two colloidal particles in a subcritical solvent is explored both by an explicit and implicit modeling. An implicit solvent approach based on a simple thermodynamic interface model is tested against grand-canonical Monte Carlo computer simulations using explicit Lennard-Jones solvent molecules. Close to liquid-gas coexistence, a joint gas bubble surrounding the colloidal particle pair yields an effective attraction between the colloidal particles, the strength of which can be vastly tuned by the solvophobicity of the colloids. The implicit model is in good agreement with our explicit computer simulations, thus enabling an efficient modeling and evaluation of colloidal interactions and self-assembly in subcritical solvent environments.
Visual Memory for Fixated Regions of Natural Images Dissociates Attraction and Recognition
Authors: van der Linde Ian , Rajashekar Umesh , Bovik Alan C , Cormack Lawrence K
Published: July 2009

Recognition memory for fixated regions from briefly viewed full-screen natural images is examined. Low-level image statistics reveal that observers fixated, on average (pooled across images and observers), image regions that possessed greater visual saliency than non-fixated regions, a finding that is robust across multiple fixation indices. Recognition-memory performance indicates that, of the fixation loci tested, observers were adept at recognising those with a particular profile of image statistics; visual saliency was found to be attenuated for unrecognised loci, despite that all regions were freely fixated. Furthermore, although elevated luminance was the local image statistic found to discriminate least between human and random image locations, it was the greatest predictor of recognition-memory performance, demonstrating a dissociation between image features that draw fixations and those that support visual memory. An analysis of corresponding eye movements indicates that image regions fixated via short-distance saccades enjoyed better recognition-memory performance, alluding to a focal rather than ambient mode of processing. Recognised image regions were more likely to have originated from areas evaluated (a posteriori) to have higher fixation density, a numerical metric of local interest. Surprisingly, memory for image regions fixated later in the viewing period exhibited no recency advantage, despite (typically) also being longer in duration, a finding for which a number of explanations are posited.
Integrating Gaze Direction and Sexual Dimorphism of Face Shape When Perceiving the Dominance of Others
Authors: Main Julie C , Jones Benedict C , DeBruine Lisa M , Little Anthony C
Published: July 2009

Although gaze direction and face shape have each been shown to affect perceptions of the dominance of others, the question whether gaze direction and face shape have independent main effects on perceptions of dominance, and whether these effects interact, has not yet been studied. To investigate this issue, we compared dominance ratings of faces with masculinised shapes and direct gaze, masculinised shapes and averted gaze, feminised shapes and direct gaze, and feminised shapes and averted gaze. While faces with direct gaze were generally rated as more dominant than those with averted gaze, this effect of gaze direction was greater when judging faces with masculinised shapes than when judging faces with feminised shapes. Additionally, faces with masculinised shapes were rated as more dominant than those with feminised shapes when faces were presented with direct gaze, but not when faces were presented with averted gaze. Collectively, these findings reveal an interaction between the effects of gaze direction and sexually dimorphic facial cues on judgments of the dominance of others, presenting novel evidence for the existence of complex integrative processes that underpin social perception of faces. Integrating information from face shape and gaze cues may increase the efficiency with which we perceive the dominance of others.
Grazing orchids: impact of florivory on two species of Caladenia (Orchidaceae)
Authors: Faast Renate , Facelli José M.
Published: July 2009

Herbivory is considered a major threat in many of the orchid-species recovery plans in Australia. Kangaroos and rabbits are the most commonly implicated herbivores; however, no studies have attempted to confirm their role. Regular monitoring of several populations of Caladenia rigida R.S.Rogers and C. tentaculata Schldl. during 3 years in the Mount Lofty Ranges, South Australia, revealed that up to 94% of flowers and 36% of seed capsules were browsed, whereas leaf herbivory was less prevalent. Furthermore, patterns of herbivory varied markedly among sites and across years. In two seasons, predation of C. rigida flowers inside a kangaroo- and rabbit-proof exclosure was equal to or higher than outside the exclosure. Florivory within populations was influenced by proximity to the habitat edge, although the direction of this response differed among sites. Various types of mesh cages were erected around plants to elucidate the size and type of herbivores. Plants protected from florivores were almost three times more likely to produce seed than were exposed plants; however, some cage types reduced pollination. Video surveillance confirmed the role of the white-winged chough, Corcorax melanorhamphos, as a florivore. The present study is the first one to identify a herbivore unequivocally, quantify the intensity and extent of floral herbivory across a range of populations, and assess the potential cost of florivory to the direct reproductive output of orchids.
Biofilm structure and bed stability of five contrasting freshwater sediments
Authors: Droppo Ian G.
Published: July 2009

Using an annular flume, erosion characteristics of five diverse sediment types (stormwater pond, contaminated lacustrine, fluvial, aquaculture waste and industrial grade kaolin sediment), each with different physical and biological characteristics, were examined for relative erosion resistance and factors contributing to bed sediment stability. Suspended flocs represent primary building blocks of bed sediment with mass settling being independent of suspended solid concentration. Biofilm growth period, depositing floc structure and composition, nutrient supply and sediment properties all played a complex role in dictating the stability of the sediments. The river, lake and stormwater pond sediments were the most resistant to erosion relative to the high nutrient and organic content aquaculture sediment and kaolin. Biofilms developed to varying degrees on all sediments with the greatest growth occurring with the aquaculture sediment and the least with kaolin. While electrochemical properties will provide some attraction and stabilising forces, with no measurable consolidation evident for the examined sediments, it is suggested that active biofilm development was the dominant factor controlling bed stability and erosion potential. Differences in biological mediation of strength between sediments were partially attributed to the structural differences within the biofilms and integration of the extracellular polymeric fibril matrix within the sediment pores.
A new radiometric instrument for in situ measurements of physical sediment properties
Authors: Jacobs W. , Eelkema M. , Limburg H. , Winterwerp J. C.
Published: July 2009

Information on the sedimentological composition of sediment beds in marine wetlands is important for the study of the complicated interactions between physical, biological and chemical processes. In situ soil sample collection and subsequent laboratory analyses using traditional methods is rather time consuming. The present paper presents the Medusa (Multi Detector system for Underwater Sediment Activity) RhoC system. ‘Rho’ refers to density and ‘C’ to the activity concentration of the decaying isotopes adhered to the sediments. The new instrument directly translates (the attenuation of) natural radioactivity to sedimentological data concerning the depth-averaged sediment composition and vertical density profiles of the upper 15 cm of the sediment bed. The accuracy and applicability of the instrument were assessed to illustrate its potential and limitations. Results from a field campaign on several intertidal flats and from similar measurements in the laboratory for controlled circumstances were compared with data obtained by traditional analyses. The instrument generates accurate results for the depth-averaged sediment composition. Vertical density profiles are also well represented by the RhoC after smoothing and correcting the data for partly saturated soils. Thus, Medusa RhoC is a useful and practical tool to provide accurate sedimentological data in a fast and cost-effective way. The combination of sedimentological relations with the data obtained by RhoC further increases the applicability of the new instrument.
Effect of Ca2+ and Na+ on the sorption of three selected endocrine disruptors to sediments
Authors: Sun Weiling , Ni Jinren , Li TianHong , Sun Liying
Published: July 2009

Endocrine disruptors (EDs) are of global concern owing to their widespread occurrence and adverse effect on reproductive systems of animals and humans. The sorption behaviour of EDs is of fundamental importance in determining their transport and fate, but the influence of solution chemistry (ion species and concentration) on the sorption process is poorly understood. In the present study, the effects of Ca2+ and Na+ on the sorption of three selected EDs (bisphenol A, 17β-oestradiol and 17α-ethynylestradiol) to sediments were investigated. Fluorescence spectra of EDs were measured to reveal the interactions of ions with EDs. The sorption of EDs to sediments increases with rising ion concentration, and Ca2+ has a greater influence on sorption than Na+. Two characteristic excitation–emission peaks were found in the three-dimensional fluorescence spectra. For the selected EDs, a strong reduction in intensity of these two peaks was observed after the addition of ions. These results indicate that solution chemistry has a major influence on the sorption of selected EDs to sediments; greater sorption occurs with higher ion concentration.
Sediment aggregation and water quality in wildfire-affected river basins
Authors: Blake W. H. , Wallbrink P. J. , Droppo I. G.
Published: July 2009

Off-site transfer of nutrient-rich burnt soil has implications for downstream water quality. Coarsening of effective particle size (EPS) distributions in burnt material via aggregation of fines into composite particles modifies post-fire sediment and nutrient transport dynamics. Experiments were undertaken to establish temperature controls on wildfire-enhanced soil aggregation. Burnt and unburnt soil from a temperate eucalypt forest were analysed for EPS and settling velocity using a LISST-ST (Laser In Situ Scatter and Transmissometry with Settling Tube) particle size analyser. Next, samples were burnt (250–550°C) before further analysis with the LISST-ST. Settling velocities of naturally burnt soil aggregates were greater than unburnt aggregates of the same EPS. Experimental burning indicated that dense water-stable aggregates form at relatively low temperatures (250°C) probably due to distillation and carbonisation, through pyrolysis, of organic volatiles in surface litter. Under these conditions, the EPS distribution of burnt surface soil coarsens with up to 50% of the <63-μm fraction becoming aggregated. A positive relationship between ‘plant-available’ phosphorus and burn temperature was observed. Given that a large proportion of soil particulate phosphorus is associated with the <63-μm fraction, fire-related aggregation processes have potentially important implications for post-fire fine sediment and nutrient transport and storage dynamics.
Density-dependent effects of bioturbation by the clam, Scrobicularia plana, on the erodibility of estuarine sediments
Authors: Soares Claudia , Sobral Paula
Published: July 2009

Benthic organisms are known to modify sediment properties and influence the flux of materials to the water column. In this study, the density-dependent effects of bioturbation by the estuarine clam, Scrobicularia plana, on the biogeochemical properties and erodibility of the sediment were assessed using laboratory annular flumes. Sediments with different mud contents (~98% and 90%) were collected undisturbed from two different sites of the Tagus estuary. S. plana were added to the sediment at increasing densities (0, 57, 115 and 229 ind m–2) and left to bioturbate the sediment before the experimental erosion runs. All erosion runs were carried out following a stepwise increase of current velocities (U) up to 0.25 m s–1. Sediment chlorophyll a, pheopigments and extracellular polymeric substance fractions were measured at the time of sampling in the field and in the end of the erosion runs. Increasing densities of S. plana in the muddier sediment raised eroded mass, while the sediment with less mud behaved as non-cohesive and registered a decrease in eroded mass possibly due to a switch in the feeding behaviour of S. plana.
Thirty years of sediment - water science: history, trends and future directions
Authors: Petticrew Ellen L.
Published: July 2009

In 1976, an interdisciplinary group of international researchers met in Amsterdam to share their knowledge about sediment–water interactions, and subsequently formed the International Association for Sediment Water Science (IASWS). Since then, IASWS has met tri-annually at a variety of locations throughout the world. Over the last 30 years, over 1000 oral presentations have been presented at IASWS symposia, more than half of which have been published as books or special issues of scientific journals. As such, the publications provide an excellent record of developments in the field of sediment–water interactions over the last 30 years. This paper provides an overview of the history of the Association, and a qualitative and quantitative content analysis of the IASWS publications. Changing patterns of research in some of the dominant symposia themes, including sediment-associated nutrients, contaminants and metals as well as sediment dynamics and material cycling are presented. Temporal changes in the investigative scale of published studies and an eventual increase in papers addressing management considerations were observed. Potential directions for the future of IASWS and some directives for ensuring that future research informs aquatic ecosystem health are suggested.
A recombinant N-terminal domain fully restores deactivation gating in N-truncated and long QT syndrome mutant hERG potassium channels
Authors: Gustina Ahleah S. , Trudeau Matthew C.
Published: July 2009

Human ether á go-go related gene (hERG) potassium channels play a central role in cardiac repolarization where channel closing (deactivation) regulates current density during action potentials. Consequently, mutations in hERG that perturb deactivation are linked to long QT syndrome (LQTS), a catastrophic cardiac arrhythmia. Interactions between an N-terminal domain and the pore-forming “core” of the channel were proposed to regulate deactivation, however, despite its central importance the mechanistic basis for deactivation is unclear. Here, to more directly examine the mechanism for regulation of deactivation, we genetically fused N-terminal domains to fluorescent proteins and tested channel function with electrophysiology and protein interactions with Förster resonance energy transfer (FRET) spectroscopy. Truncation of hERG N-terminal regions markedly sped deactivation, and here we report that reapplication of gene fragments encoding N-terminal residues 1–135 (the “eag domain”) was sufficient to restore regulation of deactivation. We show that fluorophore-tagged eag domains and N-truncated channels were in close proximity at the plasma membrane as determined with FRET. The eag domains with Y43A or R56Q (a LQTS locus) mutations showed less regulation of deactivation and less FRET, whereas eag domains restored regulation of deactivation gating to full-length Y43A or R56Q channels and showed FRET. This study demonstrates that direct, noncovalent interactions between the eag domain and the channel core were sufficient to regulate deactivation gating, that an LQTS mutation perturbed physical interactions between the eag domain and the channel, and that small molecules such as the eag domain represent a novel method for restoring function to channels with disease-causing mutations.
The eye lens chaperone α-crystallin forms defined globular assemblies
Authors: Peschek Jirka , Braun Nathalie , Franzmann Titus M. , Georgalis Yannis , Haslbeck Martin , Weinkauf Sevil , Buchner Johannes
Published: July 2009

α-Crystallins are molecular chaperones that protect vertebrate eye lens proteins from detrimental protein aggregation. αB-Crystallin, 1 of the 2 α-crystallin isoforms, is also associated with myopathies and neuropathological diseases. Despite the importance of α-crystallins in protein homeostasis, only little is known about their quaternary structures because of their seemingly polydisperse nature. Here, we analyzed the structures of recombinant α-crystallins using biophysical methods. In contrast to previous reports, we show that αB-crystallin assembles into defined oligomers consisting of 24 subunits. The 3-dimensional (3D) reconstruction of αB-crystallin by electron microscopy reveals a sphere-like structure with large openings to the interior of the protein. αA-Crystallin forms, in addition to complexes of 24 subunits, also smaller oligomers and large clusters consisting of individual oligomers. This propensity might explain the previously reported polydisperse nature of α-crystallin.
The fatal fungal outbreak on Vancouver Island is characterized by enhanced intracellular parasitism driven by mitochondrial regulation
Authors: Ma Hansong , Hagen Ferry , Stekel Dov J. , Johnston Simon A. , Sionov Edward , Falk Rama , Polacheck Itzhack , Boekhout Teun , May Robin C.
Published: July 2009

In 1999, the population of Vancouver Island, Canada, began to experience an outbreak of a fatal fungal disease caused by a highly virulent lineage ofCryptococcus gattii. This organism has recently spread to the Canadian mainland and Pacific Northwest, but the molecular cause of the outbreak remains unknown. Here we show that the Vancouver Island outbreak (VIO) isolates have dramatically increased their ability to replicate within macrophages of the mammalian immune system in comparison with otherC. gattiistrains. We further demonstrate that such enhanced intracellular parasitism is directly linked to virulence in a murine model of cryptococcosis, suggesting that this phenotype may be the cause of the outbreak. Finally, microarray studies on 24C. gattiistrains reveals that the hypervirulence of the VIO isolates is characterized by the up-regulation of a large group of genes, many of which are encoded by mitochondrial genome or associated with mitochondrial activities. This expression profile correlates with an unusual mitochondrial morphology exhibited by the VIO strains after phagocytosis. Our data thus demonstrate that the intracellular parasitism of macrophages is a key driver of a human disease outbreak, a finding that has significant implications for a wide range of other human pathogens.
Inclusion formation and neuronal cell death through neuron-to-neuron transmission of α-synuclein
Authors: Desplats Paula , Lee He-Jin , Bae Eun-Jin , Patrick Christina , Rockenstein Edward , Crews Leslie , Spencer Brian , Masliah Eliezer , Lee Seung-Jae
Published: July 2009

Neuronal accumulation of α-synuclein and Lewy body formation are characteristic to many neurodegenerative diseases, including Parkinson's disease (PD). This Lewy pathology appears to spread throughout the brain as the disease progresses. Furthermore, recent studies showed the occurrence of Lewy pathology in neurons grafted into the brains of PD patients, suggesting the spread of pathology from the host tissues to the grafts. The mechanism underlying this propagation is unknown. Here, we show that α-synuclein is transmitted via endocytosis to neighboring neurons and neuronal precursor cells, forming Lewy-like inclusions. Moreover, α-synuclein was transmitted from the affected neurons to engrafted neuronal precursor cells in a transgenic model of PD-like pathology. Failure of the protein quality control systems, especially lysosomes, promoted the accumulation of transmitted α-synuclein and inclusion formation. Cells exposed to neuron-derived α-synuclein showed signs of apoptosis, such as nuclear fragmentation and caspase 3 activation, both in vitro and in vivo. These findings demonstrate the cell-to-cell transmission of α-synuclein aggregates and provide critical insights into the mechanism of pathological progression in PD and other proteinopathies.
Genetic structure and isolation by distance in a landrace of Thai rice
Authors: Pusadee Tonapha , Jamjod Sansanee , Chiang Yu-Chung , Rerkasem Benjavan , Schaal Barbara A.
Published: July 2009

Rice is among the 3 most important crops worldwide. While much of the world's rice harvest is based on modern high-yield varieties, traditional varieties of rice grown by indigenous groups have great importance as a resource for future crop improvement. These local landraces represent an intermediate stage of domestication between a wild ancestor and modern varieties and they serve as reservoirs of genetic variation. Such genetic variation is influenced both by natural processes such as selection and drift, and by the agriculture practices of local farmers. How these processes interact to shape and change the population genetics of landrace rice is unknown. Here, we determine the population genetic structure of a single variety of landrace rice, Bue Chomee, cultivated by Karen people of Thailand. Microsatellite markers reveal high level of genetic variation despite predominant inbreeding in the crop. Bue Chomee rice shows slight but significant genetic differentiation among Karen villages. Moreover, genetically determined traits such as flowering time can vary significantly among villages. An unanticipated result was the overall pattern of genetic differentiation across villages which conforms to an isolation by distance model of differentiation. Isolation by distance is observed in natural plant species where the likelihood of gene flow is inversely related to distance. In Karen rice, gene flow is the result of farmers' seed sharing networks. Taken together, these data suggest that landrace rice is a dynamic genetic system that responds to evolutionary forces, both natural and those imposed by humans.
Gamma and alpha motor neurons distinguished by expression of transcription factor Err3
Authors: Friese Andreas , Kaltschmidt Julia A. , Ladle David R. , Sigrist Markus , Jessell Thomas M. , Arber Silvia
Published: July 2009

Spinal motor neurons are specified to innervate different muscle targets through combinatorial programs of transcription factor expression. Whether transcriptional programs also establish finer aspects of motor neuron subtype identity, notably the prominent functional distinction between alpha and gamma motor neurons, remains unclear. In this study, we identify DNA binding proteins with complementary expression profiles in alpha and gamma motor neurons, providing evidence for molecular distinctions in these two motor neuron subtypes. The transcription factor Err3 is expressed at high levels in gamma but not alpha motor neurons, whereas the neuronal DNA binding protein NeuN marks alpha but not gamma motor neurons. Signals from muscle spindles are needed to support the differentiation of Err3
on
/NeuN
off
presumptive gamma motor neurons, whereas direct proprioceptive sensory input to a motor neuron pool is apparently dispensable. Together, these findings provide evidence that transcriptional programs define functionally distinct motor neuron subpopulations, even within anatomically defined motor pools.
Relationship between the Prevalence of Methicillin-ResistantStaphylococcus aureusInfection and Indicators of Nosocomial Infection Control Measures A Population-Based Study in French Hospitals
Authors: Grammatico-Guillon Leslie , Thiolet Jean-Michel , Bernillon Pascale , Coignard Bruno , Khoshnood Babak , Desenclos Jean-Claude
Published: July 2009

Objective.

To assess whether infection control indicators are associated with the prevalence of methicillin-resistantStaphylococcus aureus(MRSA) infection in French hospitals.

Methods.

We linked the database for the 2006 national prevalence survey of nosocomial infection with the database of infection control indicators (comprised of ICALIN, an indicator of infection control organization, resources, and action, and ICSHA, an indicator of alcohol-based handrub consumption) recorded from hospitals by the Ministry of Health. Data on MRSA infection were obtained from the national prevalence survey database and included the site and origin of infection, the microorganism responsible, and its drug resistance profile. Because the prevalence of MRSA infection was low and often nil, especially in small hospitals, we restricted our analysis to hospitals with at least 300 Patients. We used a multilevel logistic regression model to assess the joint effects of patient-level variables (eg, age, sex, or infection) and hospital-level variables (infection control indicators).

Results.

Two hundred two hospitals had at least 300 patients, for a total of 128,631 Patients. The overall prevalence of MRSA infection was 0.34% (95% confidence interval [CI], 0.29%-0.39%). The mean value for ICSHA was 7.8 L per 1,000 patient-days (median, 6.1 L per 1,000 patient-days; range, 0-33 L per 1,000 patient-days). The mean value for ICALIN was 92 of a possible 100 points (median, 94.5;range, 67-100). Multilevel analyses showed that ICALIN scores were associated with the prevalence of MRSA infection (odds ratio for a score change of 1 standard deviation, 0.80;95% CI, 0.69-0.93). We found no association between prevalence of MRSA infection and ICSHA. Other variables significantly associated with the prevalence of MRSA infection were sex, vascular or urinary catheter, previous surgery, and the McCabe score.

Conclusions.

We found a significant association between the prevalence of MRSA infection and ICALIN that suggested that a higher ICALIN score may be predictive of a lower prevalence of MRSA infection.
Routine Replacement versus Clinical Monitoring of Peripheral Intravenous Catheters in a Regional Hospital in the Home Program A Randomized Controlled Trial
Authors: Van Donk Patricia , Rickard Claire M. , McGrail Matthew R. , Doolan Glenn
Published: July 2009

This randomized, controlled trial involving 316 patients in the home setting found no difference in the rate of phlebitis and/or occlusion among patients for whom a peripheral intravenous catheter was routinely resited at 72-96 hours and those for whom it was replaced only on clinical indication (76.8 events per 1,000 device-days vs 87.3 events per 1,000 device-days; P = .71). There were no bloodstream infections.
Melting Behaviour of Shell-symmetric Aluminum Nanoparticles: Molecular Dynamics Simulation
Authors: Li Kun-jie , Huang Shi-ping , Tu Wei-xia , Zhu Ji-qin , Liu Hui
Published: July 2009

Molecular dynamics simulations with embedded atom method potential were carried out for Al nanoparticles of 561 atoms in three structures: icosahedron, decahedron, and truncated octahedron. The total potential energy and specific heat capacity were calculated to estimate the melting temperatures. The melting point is 54010 K for the icosahedral structure, 50010 K for the decahedral structure, and 52010 K for the truncated octahedral structure. With the results of mean square displacement, the bond order parameters and radius of gyration are consistent with the variation of total potential energy and specific heat capacity. The relaxation time and stretching parameters in the KohlraushWilliamWatts relaxation law were obtained by fitting the mean square displacement. The results show that the relationship between the relaxation time and the temperatures is in agreement with standard Arrhenius relation in the high temperature range.
Theoretical Calculations of Transition Probabilities and Oscillator Strengths for Sc(III) and Y(III)
Authors: Zhang Tian-yi , Zheng Neng-wu
Published: July 2009

The Weakest Bound Electron Potential Model theory is used to calculate transition probability-values and oscillator strength-values for individual lines of Sc(III) and Y(III). In this method, by solving the Schrodinger equation of the weakest bound electron, the expressions of energy eigenvalue and the radial function can be obtained. And a coupled equation is used to determine the parameters which are needed in the calculations. The obtained results of Sc(III) from this work agree very well with the accepted values taken from the National Institute of Standards and Technoligy (NIST) data base, most deviations are within the accepted level. For Y(III) there are no accepted values reported by the NIST data base. So we compared our results of Y(III) with other theoretical results, good agreement is also obtained.