bluuebunny/crossref_metadata_2025 huggingface dataset:
Selective use and spatial distribution of native and non‐native fish in wetland habitats
Authors: Cucherousset Julien , Carpentier Alexandre , Paillisson Jean‐Marc
Published: April 2008

Wetland habitats are crucial for many fish species as spawning, feeding or nursery areas, but the major factors that govern their use by fish are poorly identified. In the present study, we aim to investigate the selective use and the spatial distribution of native and non‐native fish species in different types of wetland habitats (grasslands and reed beds) in a large freshwater marsh (North Western France). The selective use was measured by comparing the community that uses wetland habitats to the total community of the marsh (sampled in the permanent aquatic habitats (canals) during the low water period). The spatial distribution was studied by analyzing the presence probability of fish in wetland habitats as a function of the distance from adjacent canals. All sampled wetland habitats were occupied by fish, and the fish community in wetland habitats was dominated by three native (Abramis brama, Scardinius erythrophthalmus and Anguilla anguilla) and three non‐native (Ameiurus melas, Gambusia holbrooki and Lepomis gibbosus) species. Species richness and total fish abundance differed between canals and wetland habitats as a consequence of a variable propensity to use wetland habitats by native (avoidance and preference) and non‐native (no preference) species. Non‐native species were also more abundant in reed beds than in grassland while no differences were observed for native species. Universally, the presence probability of fish always decreased in wetland habitats as the distance from the canals increased and only a narrow area, close to canals (50–80 m), was well used by fish. However, non‐native fish species used over greater distances in reed beds than in grasslands while no differences were observed for native species. Variable interpretations related to species tolerance, reproductive guilds or diet are proposed to understand the mechanisms that might explain the widespread success of non‐native species in this spatially varying environment. Copyright © 2008 John Wiley & Sons, Ltd.
Expression of astrocytic markers aquaporin 4 and connexin 43 is altered in brains of subjects with autism
Authors: Fatemi S. Hossein , Folsom Timothy D. , Reutiman Teri J. , Lee Susanne
Published: April 2008

Neuroanatomical studies have revealed extensive structural brain abnormalities in subjects with autism. Recently, studies have provided evidence of neuroglial responses and neuroinflammation in autism. The current study investigated whether two astrocytic markers, aquaporin 4 and connexin 43, are altered in brains from subjects with autism. Postmortem brain tissues from Brodmann's Area 40 (BA40, parietal cortex), Brodmann's Area 9 (BA9, superior frontal cortex), and cerebella of subjects with autism and matched controls were subject to SDS‐PAGE and western blotting. Connexin 43 expression was increased significantly in BA9. Aquaporin 4 expression was decreased significantly in cerebellum. These data suggest that changes are apparent in markers for abnormal glial‐neuronal communication (connexin 43 and aquaporin 4) in brains of subjects with autism. Synapse 62:501–507, 2008. © 2008 Wiley‐Liss, Inc.
The presence of consciousness in the absence of the cerebral cortex
Authors: Beshkar Majid
Published: April 2008

Hydranencephaly is a rare neurological condition in which the cerebral hemispheres are either absent or severely compromised. It is widely believed that children with hydranencephaly are not conscious; and therefore, are routinely classified into the diagnostic criteria of vegetative state. However, there are several pieces of behavioral evidence clearly indicating the presence of consciousness in such patients. Here, I review these behavioral evidence and argue how misclassification of these patients and assigning them a lack of consciousness have far‐reaching implications in terms of both clinical and theoretical neuroscience. Synapse 62:553–556, 2008. © 2008 Wiley‐Liss, Inc.
A simple method for isolating disomic strains of Saccharomyces cerevisiae
Authors: Zebrowski David C. , Kaback David B.
Published: April 2008

A simple method to select disomic (N + 1) strains that should be applicable for almost any chromosome in Saccharomyces cerevisiae is presented. A diploid heterozygous for a KanMX knock‐out mutation in an essential gene is sporulated and viable geneticin (G418)‐resistant colonies selected. Disomic products of a missegregation or non‐disjunction event containing a copy of both the wild‐type essential gene and its complementary KanMX knock‐out allele make up most of the viable colonies. This method has been used to isolate disomic haploids for a variety of chromosomes. It is appropriately named MARV (for missegregation‐associated restoration of viability) and is easily adaptable to virtually any strain. Copyright © 2008 John Wiley & Sons, Ltd.
Induction of apoptosis in yeast by L‐amino acid oxidase from the Malayan pit viper Calloselasma rhodostoma
Authors: Ande Sudharsana Rao , Fussi Heike , Knauer Heide , Murkovic Michael , Ghisla Sandro , Fröhlich Kai‐Uwe , Macheroux Peter
Published: April 2008

Here we report for the first time that L‐amino acid oxidase (LAAO), a major component of snake venom, induces apoptosis in yeast. The causative agent for induction of apoptosis has been shown to be hydrogen peroxide, produced by the enzymatic activity of LAAO. However, the addition of catalase, a specific hydrogen peroxide scavenger, does not prevent cell demise completely. Intriguingly, depletion of leucine from the medium by LAAO and the interaction of LAAO with yeast cells are shown to be the major factors responsible for cell demise in the presence of catalase. Copyright © 2008 John Wiley & Sons, Ltd.
Upper Extremity Size Differences in Brachial Plexus Birth Palsy
Authors: Bae Donald S. , Ferretti Michelle , Waters Peter M.
Published: April 2008

The purpose of this investigation was to determine size differences between affected and unaffected upper extremities in patients with brachial plexus birth palsy (BPBP). Forty-eight patients with BPBP underwent measurements of the bilateral upper extremities. Average age at the time of evaluation was 47 months. In addition, patients or families were asked “How important is the difference in arm size and appearance to you?” Active motion was assessed using the modified Mallet classification, Toronto Test Score, and Hospital for Sick Children Active Movement Scale. Correlation between ratios of affected to unaffected limb lengths and girths and measures of active motion were assessed using Spearman's rank correlation coefficient. Upper arm, forearm, and hand lengths of the affected limbs were, on average, 95%, 94%, and 97% of the contralateral unaffected side, respectively. Upper arm girth, forearm girth, and hand width were, on average, 97%, 98%, and 95% of the contralateral side, respectively. All differences achieved statistical significance ( p<0.01). Furthermore, over 37% of patients or families reported that limb differences were “very” or “extremely important” to them. No statistically significant correlation between age and limb length discrepancy was noted. Furthermore, there were no correlations between upper limb discrepancies and measures of active motion in individual patients. Patients with BPBP and persistent neurological deficits may expect the affected upper extremity to be on average approximately 95% the length and girth of the contralateral limb. These differences do not correlate with patient age or clinical measurements of active movement.
Significance of 40Ar–39Ar encapsulation ages of metapelites from late Palaeozoic metamorphic complexes of Aysén, Chile
Authors: RAMÍREZ-SÁNCHEZ ELISA , DECKART KATJA , HERVÉ FRANCISCO
Published: April 2008

The ages obtained by the 40Ar–39Ar encapsulation technique (retention and total gas ages) on <2 μm fractions of five metapelites from the Eastern Andean Metamorphic Complex and two from the Chonos Metamorphic Complex allow discussion of the latest recorded metamorphic event in each zone. The Kübler Index (KI) of illite/muscovite (principal component of the metapelites) varies between 0.15° and 0.45° Δ°2θ, indicating regional variation from diagenetic to epizonal metamorphic grade. The 40Ar–39Ar encapsulation analyses reveal 39Ar loss varying between 21 and 25%, which shows a limited positive correlation with KI values. The obtained retention and total gas metapelite ages reflect distinct metamorphic conditions. Retention ages most probably indicate burial or regional metamorphic events without plutonic influence in the southern Eastern Andean Metamorphic Complex. Total gas ages reflect contact ages for metapelites close to intrusions in the northern and southern Eastern Andean Metamorphic Complex and in the Chonos Metamorphic Complex. The thermal overprinting of metapelites occurred in Early Cretaceous times at 130 Ma and 145 Ma and is related to the contact metamorphism of an emplacement pulse of the North Patagonian Batholith. Total gas metapelite ages obtained from the western belt of the Chonos Metamorphic Complex suggest a thermal event related to a distinct pulse of the North Patagonian Batholith.
Ion-acoustic solitary waves in a multi-species magnetized plasma consisting of non-thermal and isothermal electrons
Authors: ISLAM SKANARUL , BANDYOPADHYAY A. , DAS K. P.
Published: April 2008

The Korteweg–de Vries–Zakharov–Kuznetsov (KdV-ZK) equation describes the nonlinear behaviour of long-wavelength weakly nonlinear ion-acoustic waves propagating obliquely to an external uniform (space independent) static (time independent) magnetic field in a plasma consisting of warm adiabatic ions and a superposition of two distinct population of electrons, one due to Cairns et al. (1995Geophys. Res. Lett.22, 2709), which generates the fast energetic electrons, and the other the well-known Maxwell–Boltzman distributed electrons. It is found that the compressive or rarefactive nature of the ion-acoustic solitary wave solution of the KdV-ZK equation does not depend on the ion temperature if σc<0 or σc>1, where σcis a function of β1,nscand σsc. This β1is the non-thermal parameter associated with the non-thermal velocity distribution function of electrons (Cairns et al.),nscis the ratio of the unperturbed number density of the isothermal electrons to that of the non-thermal electrons and σscis the ratio of the average temperature of the non-thermal electrons to that of the isothermal electrons. The KdV-ZK equation describes compressive or rarefactive ion-acoustic solitary wave according to whether σc<0 or σc>1. When 0 ≤ σc≤ 1, the KdV-ZK equation describes compressive or rarefactive ion-acoustic solitary wave according to whether σ>σcor σ<σc, where σ is the ratio of the average temperature of ions to the effective temperature of electrons. If σ takes the value σcwith 0 ≤ σc≤ 1, the coefficient of the nonlinear term of the KdV-ZK equation vanishes and for this case the nonlinear evolution equation of the ion-acoustic wave is a modified KdV-ZK (MKdV-ZK) equation. It is found that the four-dimensional parameter space, originated from the physically admissible values of the four-parameters β1, σ, σscandnscof the present extended plasma system, can be decomposed into five mutually disjoint subsets with respect to the critical values of the different parameters, and the nonlinear behaviour of the same ion acoustic wave in those subsets can be described by different modified KdV-ZK equations. A general method of perturbation of the dependent variables has been developed to obtain the different evolution equations. The applicability of the different evolution equations and their solitary wave solutions (along with the conditions for their existence) have been investigated analytically and graphically.
Analysis of the geodesic interpolating spline
Authors: MILLS ANNA , SHARDLOW TONY
Published: April 2008

We study the geodesic interpolating spline with a biharmonic regulariser for solving the landmark image registration problem. We show existence of solutions, discuss uniqueness and show how the problem can be efficiently solved numerically. The main advantage of the geodesic interpolating spline is that it provides a diffeomorphism and we show this is preserved under our numerical approximation.
Connexin and pannexin mediated cell–cell communication
Authors: Scemes Eliana , Suadicani Sylvia O. , Dahl Gerhard , Spray David C.
Published: April 2008

In this review, we briefly summarize what is known about the properties of the three families of gap junction proteins, connexins, innexins and pannexins, emphasizing their importance as intercellular channels that provide ionic and metabolic coupling and as non-junctional channels that can function as a paracrine signaling pathway. We discuss that two distinct groups of proteins form gap junctions in deuterostomes (connexins) and protostomes (innexins), and that channels formed of the deuterostome homologues of innexins (pannexins) differ from connexin channels in terms of important structural features and activation properties. These differences indicate that the two families of gap junction proteins serve distinct, complementary functions in deuterostomes. In several tissues, including the CNS, both connexins and pannexins are involved in intercellular communication, but have different roles. Connexins mainly contribute by forming the intercellular gap junction channels, which provide for junctional coupling and define the communication compartments in the CNS. We also provide new data supporting the concept that pannexins form the non-junctional channels that play paracrine roles by releasing ATP and, thus, modulating the range of the intercellular Ca2+-wave transmission between astrocytes in culture.
The effects of aging, injury and disease on microglial function: a case for cellular senescence
Authors: Miller Kelly R. , Streit Wolfgang J.
Published: April 2008

Neuroinflammation resulting from chronic reactive microgliosis is thought to contribute to age-related neurodegeneration, as well as age-related neurodegenerative diseases, specifically Alzheimer's disease (AD). Support of this theory comes from studies reporting a progressive, age-associated increase in microglia with an activated phenotype. Although the underlying cause(s) of this microglial reactivity is idiopathic, an accepted therapeutic strategy for the treatment of AD is inhibition of microglial activation using anti-inflammatory agents. Although the effectiveness of anti-inflammatory treatment for AD remains equivocal, microglial inhibition is being tested as a potential treatment for additional neurodegenerative disorders including amyotrophic lateral sclerosis and Parkinson's disease. Given the important and necessary functions of microglia in normal brain, careful evaluation of microglial function in the aged brain is a necessary first step in targeting more precise treatment strategies for aging-related neurodegenerative diseases. Studies from our laboratory have shown multiple age-related changes in microglial morphology and function that are suggestive of cellular senescence. In this manuscript, we review current knowledge of microglia in the aging brain and present new, unpublished work that further supports the theory that microglia experience an age-related decline in proliferative function as a result of cellular senescence.
Description and demonstration of the new Middle and Upper atmosphere Radar imaging system: 1‐D, 2‐D, and 3‐D imaging of troposphere and stratosphere
Authors: Hassenpflug G. , Yamamoto M. , Luce H. , Fukao S.
Published: April 2008

The Middle and Upper atmosphere Radar (MUR) was upgraded in March 2004 for radar imaging capability with 5 frequencies across a 1 MHz bandwidth and 25 digital receivers. Although digitization introduces problems of its own, the uniformity of digitization is a great benefit over the analogue system in place before. This increased reliability will help make the new system an important component of long‐term atmospheric science programs. We demonstrate 3‐D imaging with Capon's method, which can provide information about structure morphology. In addition, we demonstrate an experimental 0.5 μs pulse mode and compare this to Capon method imaging results.
Modeling framework for sediment deposition, storage, and evacuation in the floodplain of a meandering river: Theory
Authors: Lauer J. Wesley , Parker Gary
Published: April 2008

A theory for the movement of suspendible sediment through the floodplain of a simple actively migrating river is developed. The floodplain is represented as a series of sediment storage reservoirs, each incorporating multiple bends of a river. Independent models for floodplain sediment deposition and for subsequent removal of sediment by lateral channel migration allow the volume of sediment stored in the floodplain (and the associated average floodplain elevation) to change over time and down the valley. At a given quasi‐steady discharge, deposition depends on a simple one‐dimensional partition between channel and floodplain discharge and on suspended sediment concentration (one size class) which varies along the reach depending on lateral supply and floodplain history. Sediment supply is specified at the upstream end of the reach using a suspended sediment rating curve. Long‐term average overbank deposition rates are approximated by weighting multiple steady state solutions using a flow duration curve. The channel bed elevation of the system is assumed to be fixed, and tributaries are handled using simple lateral source terms. The interaction between the submodels is such that under constant boundary conditions, the channel evolves toward a state of geomorphic equilibrium where the volume of sediment added to the floodplain by overbank deposition just balances the volume removed by channel migration. The model is easily adapted to track conservative suspended sediment tracer material concentration as such material moves through the channel/floodplain system.
Low frequency variability in fall precipitation across the United States
Authors: Small David , Islam Shafiqul
Published: April 2008

Precipitation and streamflow have increased across the United States during the 20th century, with the largest increases observed in the fall. In this study, we apply the multitaper method with singular value decomposition (MTM‐SVD) multivariate spectral analysis to characterize the space‐time variability of fall precipitation over the United States from 1895 to 2004. MTM‐SVD analysis of precipitation demonstrates the presence of statistically significant secular and decadal signals. The decadal signal in fall precipitation, with a period of approximately 12 years, is large and spatially correlated across most of the central United States. The secular signal, with a period greater than 55 years, is weaker, much less spatially correlated and is strongest in the eastern United States. The decadal and secular variations increased in magnitude after 1950, the period when many previous studies have identified large linear trends. Linear trends in fall precipitation are found to be more spatially consistent with the pattern of decadal variations than the secular variations, suggesting that increasing decadal variations in precipitation after 1950 have contributed to large linear trends reported by several previous studies. Our results suggest that the strong spatial correlation in decadal precipitation variations across the central United States are associated with a large SLP gradient across North America that is conducive for southerly flow from the Gulf of Mexico. Secular variations in SLP associated with precipitation over the United States are located primarily in the high latitudes, and are not consistent with correlated variations in precipitation across the central United States.
A pressure gradient metric capturing planetary‐scale influences on eastern Australian rainfall
Authors: Rakich Clinton S. , Holbrook Neil J. , Timbal Bertrand
Published: April 2008

The Gayndah‐Deniliquin index (GDI), a measure of the north‐south atmospheric pressure gradient across eastern Australia, is presented. The 113 year long GDI record reveals strong interannual to decadal scale variability in zonal geostrophic wind flow across eastern Australia. The GDI, as a measure of easterly geostrophic wind strength and associated moisture transport from the Pacific Ocean, is shown to be significantly correlated with summer rainfall over vast areas of the Australian continent, especially over the Murray Darling Basin and the state of New South Wales. The latest abrupt decline in the GDI, which commenced around 2001, corresponded with the onset of a severe prolonged drought across eastern Australia. We demonstrate that the northern and southern poles of the MSLP derived GDI are differentially influenced by El Niño‐Southern Oscillation (ENSO) and the Southern Annular Mode (SAM). Understanding the effects of these interactions between SAM and ENSO on moisture transport to eastern Australia could have implications for future Australian climate variability and climate change.
Improving forecast skill by assimilation of quality‐controlled AIRS temperature retrievals under partially cloudy conditions
Authors: Reale O. , Susskind J. , Rosenberg R. , Brin E. , Liu E. , Riishojgaard L. P. , Terry J. , Jusem J. C.
Published: April 2008

The National Aeronautics and Space Administration (NASA) Atmospheric Infrared Sounder (AIRS) on board the Aqua satellite is now recognized as an important contributor towards the improvement of weather forecasts. At this time only a small fraction of the total data produced by AIRS is being used by operational weather systems. In fact, in addition to effects of thinning and quality control, the only AIRS data assimilated are radiance observations of channels unaffected by clouds. Observations in mid‐lower tropospheric sounding AIRS channels are assimilated primarily under completely clear‐sky conditions, thus imposing a very severe limitation on the horizontal distribution of the AIRS‐derived information. In this work it is shown that the ability to derive accurate temperature profiles from AIRS observations in partially cloud‐contaminated areas can be utilized to further improve the impact of AIRS observations in a global model and forecasting system. The analyses produced by assimilating AIRS temperature profiles obtained under partial cloud cover result in a substantially colder representation of the northern hemisphere lower midtroposphere at higher latitudes. This temperature difference has a strong impact, through hydrostatic adjustment, in the midtropospheric geopotential heights, which causes a different representation of the polar vortex especially over northeastern Siberia and Alaska. The AIRS‐induced anomaly propagates through the model's dynamics producing improved 5‐day forecasts.
Enhanced GPS inversion technique applied to the 2004 Sumatra earthquake and tsunami
Authors: Hoechner Andreas , Babeyko Andrey Y. , Sobolev Stephan V.
Published: April 2008

Since the devastating earthquake and tsunami in 2004 offshore Sumatra, many source models have been put forward. Recent studies clearly show that modern GPS‐processing could achieve high resolving power for slip in near real time, which is crucial for determining tsunami initial conditions, provided accurate GPS‐processing and inversion. Here, we propose an inversion technique with improved representation of the subduction zone geometry and physically justified boundary conditions. We show that the discrepancy between the inversion of near‐ and far field GPS data for the 2004 event, which is often explained by postseismic slip, can be eliminated by using our inversion method and IASP91 earth model. Inverted source models, including versions with splay faulting, are shown to be consistent with satellite altimetry data of offshore tsunami wave height, suggesting that displacement at the splay fault might have been present but was likely a second order process.
Sub‐mesoscale ocean vortex trains in the Luzon Strait
Authors: Zheng Quanan , Lin Hui , Meng Junmin , Hu Xiaomin , Song Y. Tony , Zhang Yuanzhi , Li Chunyan
Published: April 2008

This study uses the Argos satellite‐tracked surface drifter trajectory data and ENVISAT (European satellite) ASAR (advanced synthetic aperture radar) images to illustrate the ocean vortex trains (OVT) in the Luzon Strait. Two cases that occurred in the northwest of Babuyan Island are observed. The first train of three cyclonic vortices showed up on drifter trajectories from 20° to 20.5°N and from 120° to 121°E, and the second, consisting of five pairs of cyclonic‐anticyclonic vortices, occurred on the upstream side of the first one from 19.5° to 20.0°N and from 121.0° to 122.0°E and showed up on the ASAR images acquired on 19 November 2006. The total length of the vortex train axis reaches about 250 km. All vortices propagate northwestward (∼315° TN). The mean angular velocity is (2.07 ± 0.18) × 10−5 s−1. Theoretical models of ocean vortex radar image derived from radar imaging theories are used to extract dynamical parameters from ASAR imagery signatures, which include the distance between two consecutive vortices and that between two rows of vortices of (22.6 ± 1.9) km and (8.2 ± 1.2) km, respectively, the maximum rotational velocity radius as 4.70 km, and the vortex rotational angular velocity 3 × 10−5s−1. Dynamical analyses give the mean velocity of the current of 0.65 ms−1, and the propagation velocity of the vortex 0.58 ms−1. The vortex shedding rate is estimated as 2.57 × 10−5 s−1. The Reynolds number is estimated as 50 to 500. For the individual vortex and the vortex train, the Rossby numbers are O(0.4), and O(0.5), respectively, implying that both vortex and vortex train observed in the Luzon Strait have a sub‐mesoscale nature. This study also reveals a strong current with an average surface current velocity of around 0.7 ms−1 and the direction of around 315° TN flowing directly from the Pacific to SCS passing through the southern Luzon Strait. The mean flow velocity can be calculated using methods developed in this study and OVT dynamical models. This information may provide more insight to the circulation systems in the area including the origin of Kuroshio.
Four‐dimensional variational assimilation of ozone profiles from the Microwave Limb Sounder on the Aura satellite
Authors: Feng Liang , Brugge R. , Hólm E. V. , Harwood R. S. , O'Neill A. , Filipiak M. J. , Froidevaux L. , Livesey N.
Published: April 2008

Ozone profiles from the Microwave Limb Sounder (MLS) onboard the Aura satellite of the NASA's Earth Observing System (EOS) were experimentally added to the European Centre for Medium‐range Weather Forecasts (ECMWF) four‐dimensional variational (4D‐var) data assimilation system of version CY30R1, in which total ozone columns from Scanning Imaging Absorption Spectrometer for Atmospheric CHartographY (SCIAMACHY) onboard the Envisat satellite and partial profiles from the Solar Backscatter Ultraviolet (SBUV/2) instrument onboard the NOAA‐16 satellite have been operationally assimilated. As shown by results for the autumn of 2005, additional constraints from MLS data significantly improved the agreement of the analyzed ozone fields with independent observations throughout most of the stratosphere, owing to the daily near‐global coverage and good vertical resolution of MLS observations. The largest impacts were seen in the middle and lower stratosphere, where model deficiencies could not be effectively corrected by the operational observations without the additional information on the ozone vertical distribution provided by MLS. Even in the upper stratosphere, where ozone concentrations are mainly determined by rapid chemical processes, dense and vertically resolved MLS data helped reduce the biases related to model deficiencies. These improvements resulted in a more realistic and consistent description of spatial and temporal variations in stratospheric ozone, as demonstrated by cases in the dynamically and chemically active regions. However, combined assimilation of the often discrepant ozone observations might lead to underestimation of tropospheric ozone. In addition, model deficiencies induced large biases in the upper stratosphere in the medium‐range (5‐day) ozone forecasts.
Kinematics of slab tear faults during subduction segmentation and implications for Italian magmatism
Authors: Rosenbaum Gideon , Gasparon Massimo , Lucente Francesco P. , Peccerillo Angelo , Miller Meghan S.
Published: April 2008

Tectonic activity in convergent plate boundaries commonly involves backward migration (rollback) of narrow subducting slabs and segmentation of subduction zones through slab tearing. Here we investigate this process in the Italian region by integrating seismic tomography data with spatiotemporal analysis of magmatic rocks and kinematic reconstructions. Seismic tomography results show gaps within the subducting lithosphere, which are interpreted as deep (100–500 km) subvertical tear faults. The development of such tear faults is consistent with proposed kinematic reconstructions, in which different rates of subduction rollback affected different parts of the subduction zone. We further suggest a possible link between the development of tear faults and the occurrence of regional magmatic activity with transitional geochemical signatures between arc type and OIB type, associated with slab tearing and slab breakoff. We conclude that lithospheric‐scale tear faults play a fundamental role in the destruction of subduction zones. As such, they should be incorporated into reconstructions of ancient convergent margins, where tear faults are possibly represented by continental lineaments linked with magmatism and mineralization.
Statistical analysis of the sources of the cross‐polar potential for southward IMF, based on particle precipitation characteristics
Authors: Sundberg K. Å. T. , Blomberg L. G. , Cumnock J. A.
Published: April 2008

There are several proposed physical processes which may contribute to the cross‐polar potential and thus drive ionospheric convection around the polar caps. It is generally believed that magnetic reconnection is the dominant process, however dynamos such as viscous interaction and impulsive penetration are other possible contributors. A comprehensive statistical study has been conducted using data from the DMSP F13 satellite for passages along the northern hemisphere dawn‐dusk meridian, with focus on typical two‐cell convection patterns during times of steady southward IMF conditions. The results show that the low‐latitude dynamo (viscous interaction or reconnection in the LLBL) on average accounts for only 1–2 kV of the total potential drop, values lower than those previously predicted. At rare occasions this dynamo can be a significant source of energy, however, contributing to more than 20 kV of the cross‐polar potential.
Augmentative and Alternative Communication: Assessment in the Schools
Authors: Proctor Lisa A. , Oswalt Jill
Published: April 2008

The purpose of this article is to review augmentative and alternative communication (AAC) assessment issues in the schools. Initially, the article discusses the role and responsibilities of school-based speech-language pathologists in the assessment of children with complex communication needs. Next, the article briefly reflects on the importance of teaming in device selection for children with AAC needs. The main portion of the article provides information on assessment tools and resources related to comprehensive assessment for children with complex communication needs. This includes information on assessment of speech production and the relevance in AAC assessment. This is followed by tools and resources for receptive language and expressive language assessment. Also included in this main section is information on tools that examine academic and social participation. Finally, information on literacy assessment for student with complex communication needs is provided. The intent of the article is to provide the reader with a brief overview of assessment tools and resources for children with complex communication needs.
Communication Partner Interventions for Students Who Use AAC
Authors: Kent-Walsh Jennifer
Published: April 2008

Research indicates that the communication skills of partners significantly influence the success of communicative interactions with individuals who use AAC. Frequently, partners have been reported to not provide supportive opportunities for communication when interacting with individuals who use AAC. In turn, individuals who use AAC have been documented to often be passive communicators, particularly when they are at the beginning stages of developing communicative competence. Given the importance of effective communication skills in the school environment, it is essential that speech-language pathologists consider conducting partner interventions when working with school-age children with AAC needs. This article provides practical suggestions for speech-language pathologists by exploring (a) the range of communication partners who may benefit from partner interventions, (b) examples of interaction skills that can be targeted through partner interventions, and (c) a suggested protocol for communication partner interventions. By providing interventions for communication partners who are complimentary to interventions provided directly, it is possible for school SLPs to strengthen their approach to improving communication and educational outcomes for children with AAC needs.
Professional Preparedness for Provision of Auditory Oral Programs to Children With Hearing Loss: Results of a Survey
Authors: Luckhurst Joan A.
Published: April 2008

Advances in technology have facilitated development of auditory-oral skills in greater numbers of children who are deaf. In addition, mainstream educational placements are increasing for this population. Since success in the mainstream is largely dependent upon development of oral communication skills, it is imperative that professionals working with these children have competence in auditory-oral methodology. The present study investigated professionals' perceptions of preparedness to develop and implement auditory-oral programs. Professionals using an auditory-oral approach were asked about their perceived levels of knowledge and skills, pre-service training, and on-the-job factors that contributed to their competence to provide auditory-oral programs to children who are deaf. Classification tables, chi-square, and qualitative analyses were used to determine professionals' perceptions of preparedness and to identify significant differences among professional groups (i.e., speech-language pathologists, teachers of the deaf, audiologists), as well as specific aspects of pre-service and occupational training that promoted knowledge and skills. Results indicated that a significant number of professionals in all groups feel unprepared. Specific group differences and needed components for adequate preparation are discussed. Suggestions for further study are presented.
Telepractice Aural Habilitation for School-Age Children
Authors: Duncan Jill
Published: April 2008

This paper examines telepractice aural habilitation for school-age children delivered via videoconferencing. It identifies issues, concerns, and successful teaching behaviors and strategies employed in this unique environment. The paper concludes with a description of the Royal Institute for Deaf and Blind Children’s Teleschool and a case study of a 16-year-old cochlear implant user who has received intercontinental auditory-verbal therapy via videoconferencing for 24 months.
Cortical Stimulation and Aphasia: The State of the Science
Authors: Cherney Leora R.
Published: April 2008

Purpose:Biological approaches to aphasia rehabilitation involve procedures aimed to alter brain anatomy and physiology so that language function can be restored. One such approach is the application of electrical stimulation to the cerebral cortex to facilitate brain plasticity and enhance stroke recovery.

Method:This article discusses the rationale for the application of cortical stimulation and reviews three different methods of delivering cortical brain stimulation — repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (tDCS), and epidural cortical stimulation. Each of these methods has been applied to the rehabilitation of language after stroke, and some of the key studies that have addressed the use of cortical stimulation as a potential treatment for post-stroke aphasia are described.

Conclusions:Pilot results suggest a potential role for cortical stimulation as an adjuvant strategy in aphasia rehabilitation. Further investigation of each method of stimulation and its impact on language recovery is warranted. Suggestions for the direction of future research are discussed.
Typicality Treatment for Naming Deficits in Aphasia: Why Does It Work?
Authors: Kiran Swathi
Published: April 2008

Purpose:The present paper provides a review of a recent treatment approach for alleviating naming deficits in patients with aphasia. This is an example of a treatment that is theoretically based and supported by behavioral evidence from normal adult language processing.

Method:First, a theoretical basis for naming deficits in patients with aphasia is provided. Then, current options for semantic-based treatment of naming deficits are reviewed. Previous work from our laboratory indicates that training atypical examples of semantic categories resulted in generalization to untrained typical examples, whereas training typical examples did not result in generalization to untrained atypical examples.

The usefulness of the typicality treatment approach is discussed in the context of recent studies from our laboratory that have examined this approach across a variety of semantic categories, including animate categories (e.g., birds), inanimate categories (e.g., furniture), well-defined categories such as “shapes,” and goal derived categories such as “things to have in a garage sale.”

Conclusions:We suggest that the success of the treatment seemingly relies on the stringent selection of typical/atypical examples and on highlighting the variation of semantic features of the trained category as part of the treatment protocol.
The effects of molecular diffusion in ultrafast two-dimensional nuclear magnetic resonance
Authors: Shrot Yoav , Frydman Lucio
Published: April 2008

The so-called “ultrafast” nuclear magnetic resonance (NMR) methods enable the collection of multidimensional spectra within a single scan. These experiments operate by replacing traditional t1 time increments, with a series of combined radiofrequency-irradiation/magnetic-field-gradient manipulations that spatially encode the effects of the indirect-domain spin interactions. Barring the presence of sizable displacements, the spatial patterns thus imparted can be read out following a mixing period with the aid of oscillating acquisition gradients, leading to a train of t2-modulated echoes carrying in their positions and phases the indirect- and the direct-domain spin interactions. Both the initial spatial encoding as well as the subsequent spatial decoding procedures underlying ultrafast NMR were designed under the assumption that spins remain static within the sample during their execution. Most often this is not the case, and motion-related effects can be expected to affect the outcome of these experiments. The present paper focuses on analyzing the effects of diffusion in ultrafast two-dimensional (2D) NMR. Toward this end both analytical and numerical formalisms are derived, capable of dealing with the nonuniform spin manipulations, macroscopic sample sizes, and microscopic displacements involved in this kind of sequences. After experimentally validating the correctness of these formalisms these were used to analyze the effects of diffusion for a variety of cases, including ultrafast experiments on both rapidly and slowly diffusing molecules. A series of prototypical schemes were considered including discrete and continuous encoding modes, constant- and real-time manipulations, homo- and heteronuclear acquisitions, and single versus multiple quantum modalities. The effects of molecular diffusion were also compared against typical relaxation-driven losses as they happen in these various prototypical situations; from all these situations, general guidelines for choosing the optimal ultrafast 2D NMR scheme for a particular sample and condition could be deduced.
Spin cast thin polymer interlayers in polymer light-emitting diodes: Thickness control through use of cross-linkable polymers
Authors: Bernardo Gabriel , Charas Ana , Alcácer Luís , Morgado Jorge
Published: April 2008

The effect of very thin polymer interlayers made of either acid-initiated cross-linkable polyfluorenes or the parent non-cross-linkable polyfluorenes, on top of poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonic acid, on the efficiency of light-emitting diodes based on three different electroluminescent (EL) polymers is studied. We find that the use of non-cross-linkable polymers leads to the formation of interlayers with a thickness not exceeding 1nm and their effect on the light-emitting diode characteristics is not directly correlated with the energetic position of the frontier levels, indicating that other effects, such as interfacial morphology and contact area, which may depend on the specific interlayer/EL polymer combination, play a significant role. When cross-linkable polymers are used, thicker interlayers are formed (up to about 7nm), and their effect is better related to their frontier level energy. In particular, we found that with these interlayers, a quite significant EL efficiency increase can be obtained.
The low-lying πσ* state and its role in the intramolecular charge transfer of aminobenzonitriles and aminobenzethyne
Authors: Lee Jae-Kwang , Fujiwara Takashige , Kofron William G. , Zgierski Marek Z. , Lim Edward C.
Published: April 2008

Electronic absorption spectra of the low-lying ππ* and πσ* states of several aminobenzonitriles and 4-dimethylaminobenzethyne have been studied by time-resolved transient absorption and time-dependent density functional theory calculation. In acetonitrile, the lifetime of the πσ*-state absorption is very short (picoseconds or subpicosecond) for molecules that exhibit intramolecular charge transfer (ICT), and very long (nanoseconds) for those that do not. Where direct comparison of the temporal characteristics of the πσ*-state and the ICT-state transients could be made, the formation rate of the ICT state is identical to the decay rate of the πσ* state within the experimental uncertainty. These results are consistent with the πσ*-mediated ICT mechanism, La (ππ*)→πσ*→ICT, in which the decay rate of the πσ* state is determined by the rate of the solvent-controlled πσ*→ICT charge-shift reaction. The ππ*→πσ* state crossing does not occur in 3-dimethylaminobenzonitrile or 2-dimethylaminobenzonitrile, as predicted by the calculation, and 4-aminobenzonitrile and 4-dimethylaminobenzethyne does not exhibit the ICT reaction, consistent with the higher energy of the ICT state relative to the πσ* state.
Absorption intensities and emission cross section of Er3+ in Sc2O3 transparent ceramics
Authors: Gheorghe C. , Georgescu S. , Lupei V. , Lupei A. , Ikesue A.
Published: April 2008

Spectroscopic investigation of Er3+ doped Sc2O3 transparent ceramics was performed in order to assess its potential as a laser material for different emission wavelengths. The Judd–Ofelt intensity parameters for the f-f transitions of the C2-symmetry center of Er3+ in Sc2O3 transparent ceramics, inferred from the room temperature absolute intensities of the absorption bands in the 370–1600nm range, are Ω2=3.57×10−20cm2, Ω4=1.61×10−20cm2, and Ω6=0.79×10−20cm2. These parameters are comparable to those reported for Er3+ in other sesquioxide single crystals. The Judd–Ofelt intensity parameters are used to determine the emission probabilities, radiative lifetimes, and branching ratios of the different Er3+ transitions. The emission cross sections of the potential laser transitions at ∼1.5μm were determined using the reciprocity method, and the potential laser gain versus wavelength for the I13∕24→I15∕24 was analyzed.
Three-dimensional magnetohydrodynamical simulation of expanding magnetic flux ropes
Authors: Arnold L. , Dreher J. , Grauer R. , Soltwisch H. , Stein H.
Published: April 2008

Three-dimensional, time-dependent numerical simulations of the dynamics of magnetic flux ropes are presented. The simulations are targeted towards an experiment previously conducted at California Institute of Technology [P. M. Bellan and J. F. Hansen, Phys. Plasmas 5, 1991 (1998)] which aimed at simulating solar prominence eruptions in the laboratory. The plasma dynamics is described by ideal magnetohydrodynamics using different models for the evolution of the mass density. The initial current distribution represents the situation at the plasma creation phase, while it is not increased during the simulation. Key features of the reported experimental observations like pinching of the current loop, its expansion and distortion into helical shape are reproduced in the numerical simulations. Details of the final structure depend on the choice of a specific model for the mass density.
Global axisymmetric simulations of two-fluid reconnection in an experimentally relevant geometry
Authors: Murphy N. A. , Sovinec C. R.
Published: April 2008

To address the interplay between local and global effects in magnetic reconnection, axisymmetric numerical simulations for the Magnetic Reconnection Experiment [M. Yamada et al., Phys. Plasmas 4, 1936 (1997)] are performed using the NIMROD code [C. R. Sovinec et al., J. Comput. Phys. 195, 355 (2004)]. The “pull” and “push” modes of the device are simulated both with and without two-fluid effects in the generalized Ohm’s law. As in experiment, the pull reconnection rate is slowed due to the presence of downstream pressure associated with the outflow. Effects induced by toroidicity include a radially inward drift of the current sheet during pull reconnection and a radially outward displacement of the X-point during push reconnection. These effects result from the inboard side of the current sheet having less volume than the outboard side, facilitating the formation of large scale pressure gradients since the inboard side is more susceptible to a buildup or depletion of density. Toroidicity also leads to asymmetry of the quadrupole field during two-fluid simulations. During pull reconnection, the outboard lobes of the quadrupole typically peak close to the X-point, whereas the inboard quadrupole lobes peak near the flux core surfaces. At experimentally relevant parameters, the reconnection rate is found to depend more on the mode of operation than on the inclusion of two-fluid effects. The current sheet in two-fluid co-helicity simulations tilts due to a Lorentz force associated with the guide field and the outflowing electrons, resulting in asymmetric flow patterns for both ions and electrons. In two-fluid counter-helicity simulations, the Hall effect leads to a radial shift in position of the X-point and an asymmetric outflow pattern, which is examined in terms of separate force-density contributions. In general, asymmetry due to toroidicity or the Hall effect often leads to uneven outflow, which then feeds back on the reconnection process through large scale pressure gradients.