bluuebunny/crossref_metadata_2025 huggingface dataset:
SOFC Ni-electrode Resistance Distribution Investigated by Gas Concentration Impedance in a Plug-Flow Setup
Authors: Jensen So̸ren H. , Hendriksen Peter V. , Mogensen Mogens , Jacobsen Torben
Published: December 2008

In Solid Oxide Fuel Cells (SOFCs) and Solid Oxide Electrolyser Cells (SOECs) the change of reactant gasses to product gasses is one of the factors that limit the performance of the cells. Therefore it is important to have a detailed understanding of the impedance associated with this change in the gas concentrations and how it relates to various operating conditions. In this paper we describe a SOEC tested as a steam electrolyser in a plug-flow setup. The measured gas concentration impedance increases during the test, even though the current, the inlet gas concentrations and the flow rates are kept constant. From the impedance arcs we conclude that the increase must be due to a build up of an uneven resistance distribution perpendicular to (and not parallel to) the gas flow direction in the Ni-electrode.
Proton-Electron Mixed Conduction Properties in (Ce,Sr)PO4
Authors: Unemoto Atsushi , Kitamura Naoto , Amezawa Koji , Kawada Tatsuya
Published: December 2008

Mixed conductivity of proton and electron hole in (Ce,Sr)PO4 have been investigated by electrical conductivity and hydrogen permeation measurements. The partial conductivity contributions of proton and electron hole were separately evaluated from the total conductivity by assuming the defect model proposed in the preceding work. Hydrogen permeation measurements were demonstrated in order to check if and how much hydrogen permeates across the (Ce,Sr)PO4 membranes. As expected, hydrogen successfully permeated across the membranes. Use of surface catalysts was found to enhance the hydrogen permeation fluxes. This suggested that the contribution of the surface reaction to the hydrogen permeation process is remarkable. Hydrogen permeation flux through the (Ce,Sr)PO4 membranes is concluded to be essentially determined by the surface reaction process.
Hydrogen Production by Steam Dissociation using Oxygen Transport Membranes
Authors: Lee Tae H. , Park Chan Young , Dorris Steve E. , Balachandran U. (Balu)
Published: December 2008

Hydrogen production via water splitting at 900{degree sign}C has been studied with mixed-conducting SrFeCo0.5Ox (SFC2) membranes. The hydrogen production rate increased with decreasing membrane thickness, but surface reaction kinetics began to dominate the behavior of thin (<1 mm) membranes without porous layers on their surface. Membranes coated with porous SFC2 layers, on the other hand, exhibited linear behavior up to an inverse thickness of ≈4 mm-1, and they yielded a higher hydrogen production rate than uncoated membranes with a similar thickness. To increase the hydrogen production rate, a thin film of SFC2 was fabricated by a colloidal casting method. The maximum hydrogen production rate of 17.4 cm3/min-cm2 was measured at 900{degree sign}C with a ≈20-µm-thick SFC2 film. The hydrogen production rate of the film, however, was significantly lower than the expected rate based on the membrane-thickness-dependence measurement because of concentration polarization and surface kinetic limitations.
Evaluation of Electrophoretically Deposited CuMn1.8O4 Spinel Coatings On Metallic Interconnects for SOFC Applications
Authors: Huang Wenhua , Gopalan Srikanth , Pal Uday B. , Basu Soumendra
Published: December 2008

Dense and well-adhered CuMn1.8O4 spinel coatings were deposited on Crofer 22 APU substrates by electrophroetic deposition (EPD). The coatings led to a significant reduction in the oxidation rate of the stainless steel compared to the uncoated steel at 800{degree sign}C in air and showed no diffusion of Cr from the alloy into the coating. A diffusion model was developed to calculate the effective diffusivities through the coating and thermally grown oxide. These values were calculated to be 2X10-15 cm2/s and 2.5X10-16 cm2/s, respectively. The as-processed coated sample exhibited only 4.6 mΩ cm2 ASR at 800{degree sign}C.
A Flourinated Ionic Liquid as a High-Performance Fuel Cell Electrolyte
Authors: Thomson Jeffery , Dunn Patrick , Holmes Lisa , Belieres Jean-Philippe , Angell Charles A. , Gervasio Dominic
Published: December 2008

This is the first report of a fuel cell with a proton-conducting ionic liquid (pIL) electrolyte that outperforms one with aqueous concentrated (85%) phosphoric acid over all current densities. The new pIL, 2-fluoropyridinium triflate (2-FPTf), is a fluorinated pIL that was made by mixing equimolar amounts of 2-fluoropyridine and triflic acid. A Pt-catalyzed fuel cell fed dry hydrogen and oxygen gases was stable at 80{degree sign}C with neat 2-FPTf as the electrolyte. The polarization curve showed more than 15% improvement in performance (> 0.1 V cell voltage gain) compared to an identical fuel cell except with aqueous 85% phosphoric acid as the electrolyte. The stability of the fuel cell with 2-FPTf is attributed to it being a fluorinated electrolyte that does not wet Teflon. The improved fuel cell performance is attributed to low water-activity of the electrolyte leading to suppression of oxide formation on Pt and improved cathode performance. This was supported by the voltammetry of Pt in 2-FPTf electrolyte equilibrated with oxygen, which showed oxygen reduction begins near the thermodynamic limit of 1.2 V versus RHE at 80{degree sign}C.
Enhanced Rate Of Surface Diffusion Processes In Highly Dispersed PEMFC Catalysts On Surface Functionalized Carbons: Its Relationship With The Catalyst Structure
Authors: Ferreira-Aparicio Paloma
Published: December 2008

The structural characteristics of supported Pt particles as well as the support surface chemistry are shown to determine the rate of surface diffusion processes in PEMFC catalysts. The diffusion rates of oxygen and hydrogen are extremely dependent on the Pt particle size on the samples. Temperature programmed oxidation (TPO) is revealed as a very useful tool to determine the Pt particle size distribution on Pt/C catalysts. The presence of multimodal distributions can be the origin of certain discrepancies among surface area measurements obtained by means of different physical and adsorption techniques. The scrupulous control of the reduction step during the catalysts synthesis is the key for obtaining a homogeneous distribution of very small Pt crystallites. In highly dispersed samples, the presence of water associated to sulfur-containing groups on the support surface is shown to contribute to enhance the hydrogen adsorption by means of spill-over processes.
Towards Understanding Electrocatalysis in CsH2PO4-Based Fuel Cells: Platinum and Palladium Thin Film Electrodes
Authors: Louie Mary W. , Sasaki Kenji , Haile Sossina
Published: December 2008

Fuel cells based on CsH2PO4 electrolytes have demonstrated promising power densities, but the kinetics of electrode reactions remain largely uncharacterized. Here, the hydrogen oxidation kinetics of Pd and Pt thin film electrodes on CsH2PO4 are probed using A.C. impedance spectroscopy under humidified H2/Ar gas mixtures. It was found that the polarization resistance of the Pd electrode is approximately ten times smaller than that of the Pt electrode. Furthermore, the electrode polarization resistances for both the Pd | CsH2PO4 | Pd and Pt | CsH2PO4 | Pt systems increase significantly on cooling through the superprotonic phase transition, suggesting that the rate-limiting processes for hydrogen oxidation are closely tied to proton dynamics in the CsH2PO4 electrolyte.
Modelling of Gas Flow and Electrochemical Effects in a Single Chamber-Solid Oxide Fuel Cell (SC-SOFC)
Authors: Akhtar Naveed , Decent Stephen , Loghin Daniel , Kendall Kevin
Published: December 2008

A comparison of the gas flow distribution and reactant utilization in a single chamber solid oxide fuel cell (SCSOFC) between the parallel and perpendicular cell configuration (with respect to the gas flow direction) has been discussed in detail. An electrochemical-fluid coupled numerical model in a five layer membrane electrode assembly (MEA) is developed. The model accounts for the major transports of convective and diffusive mass transfer, electrode kinetics, and potential fields. The results show gas flow and electrochemical effects inside the cell in each configuration and suggest that the parallel design provides better gas flow than perpendicular configuration. A uniform reactant utilization is observed in case of perpendicular design as compared to the parallel configuration. In order to take advantage of both the gas flow and electrochemical performance of the cell, use of a fully porous cell (including porosity of the electrolyte) is suggested in perpendicular configuration. The model can predict the effect of gas flow/ electrochemical performance, especially in situations where several cells are placed at different distances in the duct. The model is solved using COMSOL Multiphysics 3.3a, a commercial finite element analysis (FEM) software package.
Directed differentiation of mouse cochlear neural progenitors in vitro
Authors: Lin Jizhen , Feng Ling , Hamajima Yuki , Komori Masahiro , Burns Terry C. , Fukudome Shinji , Anderson John , Wang Dong , Verfaillie Catherine M. , Low Walter C.
Published: December 2008

Multipotent cochlear neural progenitors (CNPs) in the organ of Corti hold the promise for cell replacement in degenerative hearing disorders. However, not much is known about the CNPs and the specific conditions for their differentiation. Here we isolate the CNPs from the postnatal day 1 organ of Corti in mice and demonstrate their capability to self-renew and to differentiate into hair cell-like and neuronal cell-like phenotypes under the guidance of sonic hedgehog (SHH), epidermal growth factor (EGF), retinoic acid (RA), and brain-derived neurotrophic factor (BDNF), herein termed SERB (abbreviation of SHH, EGF, RA, and BDNF) in an asymmetric or symmetric manner from clonal isolates. Differentiation of CNPs into hair cells by SERB was dependent on the ERK signaling pathway, whereas the differentiation of CNPs into neurons by SERB was not. This work develops a new in vitro methodology for the maintenance and self-regeneration of CNPs for future design of regenerative strategies for hearing disorders.
The amino-terminal peptide of Bax perturbs intracellular Ca2+ homeostasis to enhance apoptosis in prostate cancer cells
Authors: Li Na , Lin Peihui , Cai Chuanxi , Pan Zui , Weisleder Noah , Ma Jianjie
Published: December 2008

During apoptosis, proteolytic cleavage of Bax at the amino terminus generates a truncated Bax of ∼18 kDa (p18Bax) and an amino-terminal peptide of ∼3 kDa (p3Bax). Whereas extensive studies have shown that p18Bax behaves like a BH3 protein with enhanced pro-apoptotic function over that of the full-length Bax (p21Bax), little is known about the function of p3Bax in apoptosis. We have previously shown that Bax and Ca2+ play a synergistic role in amplifying apoptosis signaling and that store-operated Ca2+ entry (SOCE) contributes to Bax-mediated apoptosis in prostate cancer cells. Here we test whether p3Bax can contribute to regulation of Ca2+ signaling during apoptosis through use of a membrane-penetrating peptide to facilitate delivery of recombinant p3Bax into NRP-154 cells, a prostate epithelial cell line with tumorigenic capacity. We find that human immunodefficiency virus transactivator of transcription protein (TAT)-p3Bax fusion peptide can enhance thapsigargin-induced apoptosis in NRP-154 cells, elevate SOCE activity, and increase inositol 1,4,5-trisphosphate-sensitive intracellular Ca2+ stores. Our data indicates that p3Bax can modulate the entry of extracellular Ca2+ and thus regulate the amplification of apoptosis in prostate cancer cells.
C-peptide reverses TGF-β1-induced changes in renal proximal tubular cells: implications for treatment of diabetic nephropathy
Authors: Hills Claire E. , Al-Rasheed Nawal , Al-Rasheed Nouf , Willars Gary B. , Brunskill Nigel J.
Published: December 2008

The crucial pathology underlying progressive chronic kidney disease in diabetes is tubulointerstitial fibrosis. Central to this process is epithelial-mesenchymal transformation (EMT) of proximal tubular epithelial cells driven by maladaptive transforming growth factor-β1 (TGF-β1) signaling. Novel signaling roles for C-peptide have recently been discovered with evidence emerging that C-peptide may mitigate microvascular complications of diabetes. We studied the potential for C-peptide to interrupt injurious TGF-β1 signaling pathways and thus block development of EMT in HK2 human kidney proximal tubular cells. Cells were incubated with TGF-β1 either alone or with C-peptide in low or high glucose. Changes in cell morphology, TGF-β1 receptor expression, vimentin, E-cadherin, and phosphorylated Smads were assessed. Luciferase reporters were used to assess Smad activity. The cytoskeleton was visualized by TRITC-phalloidin staining. The typical TGF-β1-stimulated, EMT-associated morphological alterations of proximal tubular cells, including increased vimentin expression, decreased E-cadherin expression, and cytoskeletal rearrangements, were prevented by C-peptide treatment. C-peptide also blocked TGF-β1-induced upregulation of expression of both type I and type II TGF-β1 receptors and attenuated TGF-β1-mediated Smad phosphorylation and Smad transcriptional activity. These effects of C-peptide were inhibited by pertussis toxin. The results demonstrate that C-peptide almost completely reversed the morphological changes in PT cells induced by TGF-β1 and suggest a role or C-peptide as a renoprotective agent in diabetic nephropathy.
Behavioral Evidence of Separate Adaptation Mechanisms Controlling Saccade Amplitude Lengthening and Shortening
Authors: Panouillères Muriel , Weiss Tiffany , Urquizar Christian , Salemme Roméo , Munoz Douglas P. , Pélisson Denis
Published: December 2008

The accuracy of saccadic eye movements is maintained over the long term by adaptation mechanisms that decrease or increase saccade amplitude. It is still unknown whether these opposite adaptive changes rely on common mechanisms. Here, a double-step target paradigm was used to adaptively decrease (backward second target step) or increase (forward step) the amplitude of reactive saccades in one direction only. To test which sensorimotor transformation stages are subjected to these adaptive changes, we measured their transfer to antisaccades in which sensory and motor vectors are spatially dissociated. In the backward adaptation condition, all subjects showed a significant amplitude decrease for adapted prosaccades and a significant transfer of adaptation to antisaccades performed in the adapted direction, but not to oppositely directed antisaccades elicited by a target jump in the adapted direction. In the forward adaptation condition, only 14 of 19 subjects showed a significant amplitude increase for prosaccades and no significant adaptation transfer to antisaccades was detected in either the adapted or nonadapted direction. These findings suggest that, whereas the level(s) of forward adaptation cannot be resolved, the mechanisms involved in backward adaptation of reactive saccades take place at a sensorimotor level downstream from the vector inversion process of antisaccades and differ markedly from those involved in forward adaptation.
Clinical Use of PPARγ Ligands in Cancer
Authors: Hatton Jennifer L. , Yee Lisa D.
Published: December 2008

The role of PPARγ in adipocyte differentiation has fueled intense interest in the function of this steroid nuclear receptor for regulation of malignant cell growth and differentiation. Given the antiproliferative and differentiating effects of PPARγ ligands on liposarcoma cells, investigation of PPARγ expression and ligand activation in other solid tumors such as breast, colon, and prostate cancers ensued. The anticancer effects of PPARγ ligands in cell culture and rodent models of a multitude of tumor types suggest broad applicability of these agents to cancer therapy. This review focuses on the clinical use of PPARγ ligands, specifically the thiazolidinediones, for the treatment and prevention of cancer.
Genomic Resources and Tools for Gene Function Analysis in Potato
Authors: Bryan Glenn J. , Hein Ingo
Published: December 2008

Potato, a highly heterozygous tetraploid, is undergoing an exciting phase of genomics resource development. The potato research community has established extensive genomic resources, such as large expressed sequence tag (EST) data collections, microarrays and other expression profiling platforms, and large-insert genomic libraries. Moreover, potato will now benefit from a global potato physical mapping effort, which is serving as the underlying resource for a full potato genome sequencing project, now well underway. These tools and resources are having a major impact on potato breeding and genetics. The genome sequence will provide an invaluable comparative genomics resource for cross-referencing to the other Solanaceae, notably tomato, whose sequence is also being determined. Most importantly perhaps, a potato genome sequence will pave the way for the functional analysis of the large numbers of potato genes that await discovery. Potato, being easily transformable, is highly amenable to the investigation of gene function by biotechnological approaches. Recent advances in the development of Virus Induced Gene Silencing (VIGS) and related methods will facilitate rapid progress in the analysis of gene function in this important crop.
One‐Dimensional Hurwitz Spaces, Modular Curves, and Real Forms of Belyi Meromorphic Functions
Authors: Costa Antonio F. , Izquierdo Milagros , Riera Gonzalo
Published: December 2008

Hurwitz spaces are spaces of pairs (S, f) where S is a Riemann surface and a meromorphic
function. In this work, we study 1‐dimensional Hurwitz spaces of meromorphic p‐fold functions with four branched points, three
of them fixed; the corresponding monodromy representation over each branched
point is a product of (p − 1)/2 transpositions and the monodromy group
is the dihedral group Dp. We prove that the completion of the Hurwitz space is
uniformized by a non‐nomal index p + 1 subgroup of a triangular group with
signature (0; [p, p, p]). We also establish the relation of the meromorphic
covers with elliptic functions and show that is a
quotient of the upper half plane by the modular group Γ(2)∩Γ0(p). Finally, we study the real forms of the Belyi projection
and show that
there are two nonbicoformal equivalent such real forms which are topologically conjugated.
Nanomaterials for Hydrogen Storage Applications: A Review
Authors: Niemann Michael U. , Srinivasan Sesha S. , Phani Ayala R. , Kumar Ashok , Goswami D. Yogi , Stefanakos Elias K.
Published: December 2008

Nanomaterials have attracted great interest in recent years because of the unusual mechanical, electrical, electronic, optical, magnetic and surface properties. The high surface/volume ratio of these materials has significant implications with respect to energy storage. Both the high surface area and the opportunity for nanomaterial consolidation are key attributes of this new class of materials for hydrogen storage devices. Nanostructured systems including carbon nanotubes, nano‐magnesium based hydrides, complex hydride/carbon nanocomposites, boron nitride nanotubes, TiS2/MoS2 nanotubes, alanates, polymer nanocomposites, and metal organic frameworks are considered to be potential candidates for storing large quantities of hydrogen. Recent investigations have shown that nanoscale materials may offer advantages if certain physical and chemical effects related to the nanoscale can be used efficiently. The present review focuses the application of nanostructured materials for storing atomic or molecular hydrogen. The synergistic effects of nanocrystalinity and nanocatalyst doping on the metal or complex hydrides for improving the thermodynamics and hydrogen reaction kinetics are discussed. In addition, various carbonaceous nanomaterials and novel sorbent systems (e.g. carbon nanotubes, fullerenes, nanofibers, polyaniline nanospheres and metal organic frameworks etc.) and their hydrogen storage characteristics are outlined.
A genome assembly-integrated dog 1 Mb BAC microarray: a cytogenetic resource for canine cancer studies and comparative genomic analysis
Authors: Thomas R. , Duke S.E. , Karlsson E.K. , Evans A. , Ellis P. , Lindblad-Toh K. , Langford C.F. , Breen M.
Published: December 2008

Molecular cytogenetic studies have been instrumental in defining the nature of numerical and structural chromosome changes in human cancers, but their significance remains to be fully understood. The emergence of high quality genome assemblies for several model organisms provides exciting opportunities to develop novel genome-integrated molecular cytogenetic resources that now permit a comparative approach to evaluating the relevance of tumor-associated chromosome aberrations, both within and between species. We have used the dog genome sequence assembly to identify a framework panel of 2,097 bacterial artificial chromosome (BAC) clones, selected at intervals of approximately one megabase. Each clone has been evaluated by multicolor fluorescence in situ hybridization (FISH) to confirm its unique cytogenetic location in concordance with its reported position in the genome assembly, providing new information on the organization of the dog genome. This panel of BAC clones also represents a powerful cytogenetic resource with numerous potential applications. We have used the clone set to develop a genome-wide microarray for comparative genomic hybridization (aCGH) analysis, and demonstrate its application in detection of tumor-associated DNA copy number aberrations (CNAs) including single copy deletions and amplifications, regional aneuploidy and whole chromosome aneuploidy. We also show how individual clones selected from the BAC panel can be used as FISH probes in direct evaluation of tumor karyotypes, to verify and explore CNAs detected using aCGH analysis. This cytogenetically validated, genome integrated BAC clone panel has enormous potential for aiding gene discovery through a comparative approach to molecular oncology.
Associations between Patterns of EEG Abnormalities and Diagnosis in a Large Memory Clinic Cohort
Authors: Liedorp M. , van der Flier W.M. , Hoogervorst E.L.J. , Scheltens P. , Stam C.J.
Published: December 2008

Aim: To describe associations of abnormalities in the electroencephalogram (EEG) with the most prevalent diagnoses in a memory clinic cohort. Methods: Associations between visual EEG findings and diagnoses in 1,116 consecutive patients [382 Alzheimer’s disease (AD), 274 subjective complaints, 190 mild cognitive impairment (MCI), 118 psychiatric disorder, 61 frontotemporal lobar degeneration, 53 vascular dementia (VaD), 38 dementia with Lewy bodies (DLB)] were determined by prevalence ratio (PR). Results: Diagnoses of subjective complaints [PR = 1.6; 95% confidence interval (CI) = 1.4–1.9] and psychiatric disorder (1.4; 95% CI = 1.1–1.9) were associated with a normal EEG, while subjects with both focal and diffuse EEG disturbances were more likely to have DLB (3.5; 95% CI = 2.1–5.6), VaD (2.3; 95% CI = 1.4–3.6) or AD (1.5; 95% CI = 1.3–1.8). Subjects with only diffuse EEG abnormalities were more likely to have AD (PR = 1.5; 95% CI = 1.3–1.9). The prevalence of MCI was higher among those with only focal EEG abnormalities (PR = 1.3; 95% CI = 1.0–1.7). Conclusions: A normal EEG argues for subjective complaints or psychiatric diagnosis. An EEG with only focal abnormalities supports MCI. An EEG with only diffuse abnormalities argues for AD. An EEG with both focal and diffuse abnormalities argues for DLB, VaD or AD.
Differential Susceptibility to Extinction-Induced Despair and Age-Dependent Alterations in the Hypothalamic-Pituitary-Adrenal Axis and Neurochemical Parameters
Authors: Topic Bianca , Oitzl Melly S. , Meijer Onno C. , Huston Joseph P. , de Souza Silva Maria A.
Published: December 2008

Clinical studies point to structural differences in the neurobiological mechanisms underlying early versus late onset of depression. However, studies examining the neuropathology of depressive-like behavior induced in the aged rodent are sparse. Extinction of learned behavior induces be- havioral ‘despair’, and is held to provide a conceptual and empirical model of human depression resulting from the withdrawal of reinforcement. We tested whether the neuroendocrinological and chemical concomitants of susceptibility to extinction-induced despair in aged animals differed from adult ones. Following the withholding of reinforcement (extinction of escape from a water maze), a number of aged and adult rats are prone to develop depressive-like behavior, i.e. immobility. Analysis of hypothalamus-pituitary-adrenal (HPA) axis markers revealed an increase in the mineralocorticoid/glucocorticoid receptor (MR/GR) mRNA ratio in the CA1 region of the hippocampus in aged and adult despair animals; however, in dependence on age, divergent changes contributed to the enhanced ratio. While aged despair rats had less GR mRNA, adult despair rats had more MR mRNA. Furthermore, age- and despair-related interactions with hippocampal and cortical steroid receptor co-activators and neurotransmitter contents in diverse brain areas were found. For instance, adult despair rats had an increased, and aged despair rats a decreased, DOPAC/dopamine turnover compared to the respective non-despair group. These results show that neurobiological underpinnings of depression in the aged differ from those of adults, and underline the importance of investigating age-related alterations in HPA axis dynamics in conjunction with neurotransmitter systems to advance our knowledge about neuronal mechanisms of late-life and/or late-onset depression.
Histochemical Detection of Ischemia-Like Alterations Induced in Kidney Tissue in vitro – Different Sensitivity to Oxidant Stress of Glomerular ENTPD1 versus E5NT
Authors: Vlaar Alexander P.J. , van Son Willem J. , Bakker Winston W.
Published: December 2008

The expression of ENTPD1 (ecto-nucleoside triphosphate diphosphohydrolase) along the glomerular microvasculature of the kidney is downregulated in ischemic conditions, in contrast to E5NT (ecto-5′-nucleotidase), which may explain the increased tendency for intraglomerular microthrombus formation in vivo. It has been suggested that in ischemia, reactive oxygen species (ROS) affect glomerular ENTPD1, whereas E5NT seems less sensitive to oxidant stress. To test this hypothesis, a soluble ATP and ADP hydrolyzing enzyme solution (apyrase) [0.4 U/ml] or 5′-nucleotidase solution [0.33 U/ml] as well renal tissue were exposed to ROS, generated by γ-irradiation in vitro. The enzymes diluted in distilled water or cryostat rat kidney sections were exposed to γ-irradiation (0.037 Gy/s) for 0, 2, 5, 10, or 15 min, with or without supplementation of the ROS scavenger dimethylsulfoxide (DMSO). The enzyme activity of the samples was biochemically tested using standard methods, before and after irradiation. The reaction product of irradiated versus nonirradiated kidney sections was semiquantitatively evaluated after histochemical staining for either glomerular ENTPD1 or glomerular E5NT expression. The results show that the enzyme activity in samples of soluble apyrase was significantly decreased after irradiation. This effect was inhibited by DMSO. In contrast, 5′-nucleotidase activity showed only a limited decline of the activity curve after irradiation, which could also be restored following supplementation of DMSO. Glomerular ENTPD1 expression showed significant decrease after irradiation of kidney sections; again, this was inhibitable by DMSO. Glomerular E5NT activity was not altered by irradiation and DMSO supplementation did not affect its activity. It is concluded that soluble apyrase as well as the glomerular ENTPD1 are sensitive to oxidant stress, which may explain their downregulation in the ischemic condition in vivo. However, soluble 5′-nucleotidase and E5NT seem much less sensitive to ROS. This relative insensitivity of E5NT to oxidant injury may counteract ischemic injury by promoting local generation of adenosine in the ischemic micro-environment.
Developmental Species Differences in Brain Cell Cycle Rates between Northern Bobwhite Quail (Colinus virginianus) and Parakeets (Melopsittacus undulatus): Implications for Mosaic Brain Evolution
Authors: Charvet Christine J. , Striedter Georg F.
Published: December 2008

Adult brains differ among species in the proportional sizes of their major subdivisions. For example, the telencephalon occupies 71% of the entire brain in parakeets (Melopsittacus undulatus) but only 54% in quail (Colinus virginianus). In contrast, the tectum is smaller in parakeets than in quail. To determine whether these differences in brain region size arise because of species differences in cell cycle rates, parakeet and quail embryos were collected at various stages of development (HH24–HH37) and stained with antibodies against proliferating cell nuclear antigen (PCNA), which labels all dividing cells, and phosphorylated histone-3 (pH3), which labels M-phase cells. Analysis of pH3+ cell densities and pH3+/PCNA+ cell ratios were used to compare cell cycle rates across stages and species. Cumulative labeling with bromodeoxyuridine (BrdU) was also used to compare cell cycle rates at stages 24 and 28 in quail. We found that telencephalic cell cycle rates lengthen with age in both species, but that they lengthen significantly later in parakeets than in quail. This species difference in cell cycle rates explains, at least partly, why adult parakeets have a proportionately larger telencephalon. Tectal cell cycle rates also remain elevated for a prolonged period of time in parakeets compared to quail. This seems paradoxical at first, given that the parakeet’s adult tectum is relatively small. However, the tectum is initially much smaller but then grows more extensively in parakeets than in quail. Thus, species differences in adult brain proportions can be traced back to species differences in cell cycle kinetics.
Pulse Pressure – Independent Predictor of Poor Early Outcome and Mortality following Ischemic Stroke
Authors: Grabska Katarzyna , Niewada Maciej , Sarzyńska-Długosz Iwona , Kamiński Bogumił , Członkowska Anna
Published: December 2008

Background: Pulse pressure (PP) in acute stroke may be related to the outcome. The link between PP in the first week following ischemic stroke and early outcome was assessed. Methods: We calculated mean PPs during the first 7 days after stroke onset in 1,677 patients. Poor outcome at hospital discharge was defined as a modified Rankin scale score of 3 or more points or death. Logistic regression was developed to evaluate PP as an independent predictor of early outcome. Results: For patients with poor outcomes the mean PP during the first week was higher than that for patients with non-poor outcomes. A logistic regression model confirmed that elevated mean PP was independently associated with poor outcome at discharge and 30-day mortality. Conclusion: Elevated PP during the acute phase of ischemic stroke is an independent predictor of poor early outcome at hospital discharge and 30-day mortality.
Real-Time Water Vapor Maps from a GPS Surface Network: Construction, Validation, and Applications
Authors: de Haan Siebren , Holleman Iwan , Holtslag Albert A. M.
Published: December 2008

In this paper the construction of real-time integrated water vapor (IWV) maps from a surface network of global positioning system (GPS) receivers is presented. The IWV maps are constructed using a two-dimensional variational technique with a persistence background that is 15 min old. The background error covariances are determined using a novel two-step method, which is based on the Hollingsworth–Lonnberg method. The quality of these maps is assessed by comparison with radiosonde observations and IWV maps from a numerical weather prediction (NWP) model. The analyzed GPS IWV maps have no bias against radiosonde observations and a small bias against NWP analysis and forecasts up to 9 h. The standard deviation with radiosonde observations is around 2 kg m−2, and the standard deviation with NWP increases with increasing forecast length (from 2 kg m−2 for the NWP analysis to 4 kg m−2 for a forecast length of 48 h). To illustrate the additional value of these real-time products for nowcasting, three thunderstorm cases are discussed. The constructed GPS IWV maps are combined with data from the weather radar, a lightning detection network, and surface wind observations. All cases show that the location of developing thunderstorms can be identified 2 h prior to initiation in the convergence of moist air.
Influence of ENSO on the West African Monsoon: Temporal Aspects and Atmospheric Processes
Authors: Joly Mathieu , Voldoire Aurore
Published: December 2008

A significant part of the West African monsoon (WAM) interannual variability can be explained by the remote influence of El Niño–Southern Oscillation (ENSO). Whereas the WAM occurs in the boreal summer, ENSO events generally peak in late autumn. Statistics show that, in the observations, the WAM is influenced either during the developing phase of ENSO or during the decay of some long-lasting La Niña events. The timing of ENSO thus seems essential to the teleconnection process. Composite maps for the developing ENSO illustrate the large-scale mechanisms of the teleconnection. The most robust features are a modulation of the Walker circulation and a Kelvin wave response in the high troposphere.

In the Centre National de Recherches Météorologiques Coupled Global Climate Model, version 3 (CNRM-CM3), the teleconnection occurs unrealistically at the end of ENSO events. An original sensitivity experiment is presented in which the ocean component is forced with a reanalyzed wind stress over the tropical Pacific. This allows for the reproduction of the observed ENSO chronology in the coupled simulation. In CNRM-CM3, the atmospheric response to ENSO is slower than in the reanalysis data, so the influence on the WAM is delayed by a year.

The two principal features of the teleconnection are the timing of ENSO onsets and the time lag of the atmospheric response. Both are assessed separately in 16 twentieth-century simulations of the third phase of the Coupled Model Intercomparison Project (CMIP3). The temporal aspects of the ENSO teleconnection are reproduced with difficulty in state-of-the-art coupled models. Only four models simulate an impact of ENSO on the WAM during the developing phase.
Independent Component Analysis of Climate Data: A New Look at EOF Rotation
Authors: Hannachi A. , Unkel S. , Trendafilov N. T. , Jolliffe I. T.
Published: December 2008

The complexity inherent in climate data makes it necessary to introduce more than one statistical tool to the researcher to gain insight into the climate system. Empirical orthogonal function (EOF) analysis is one of the most widely used methods to analyze weather/climate modes of variability and to reduce the dimensionality of the system. Simple structure rotation of EOFs can enhance interpretability of the obtained patterns but cannot provide anything more than temporal uncorrelatedness. In this paper, an alternative rotation method based on independent component analysis (ICA) is considered. The ICA is viewed here as a method of EOF rotation. Starting from an initial EOF solution rather than rotating the loadings toward simplicity, ICA seeks a rotation matrix that maximizes the independence between the components in the time domain. If the underlying climate signals have an independent forcing, one can expect to find loadings with interpretable patterns whose time coefficients have properties that go beyond simple noncorrelation observed in EOFs. The methodology is presented and an application to monthly means sea level pressure (SLP) field is discussed. Among the rotated (to independence) EOFs, the North Atlantic Oscillation (NAO) pattern, an Arctic Oscillation–like pattern, and a Scandinavian-like pattern have been identified. There is the suggestion that the NAO is an intrinsic mode of variability independent of the Pacific.
The Effect of Large-Scale Atmospheric Uncertainty on Streamflow Predictability
Authors: Hou Dingchen , Mitchell Kenneth , Toth Zoltan , Lohmann Dag , Wei Helin
Published: December 2008

Hydrological processes are strongly coupled with atmospheric processes related, for example, to precipitation and temperature, and a coupled atmosphere–land surface system is required for a meaningful hydrological forecast. Since the atmosphere is a chaotic system with limited predictability, ensemble forecasts offer a practical tool to predict the future state of the coupled system in a probabilistic fashion, potentially leading to a more complete and informative hydrologic prediction. As ensemble forecasts with coupled meteorological–hydrological models are operationally running at major numerical weather prediction centers, it is currently possible to produce a gridded streamflow prognosis in the form of a probabilistic forecast based on ensembles. Evaluation and improvement of such products require a comprehensive assessment of both components of the coupled system.

In this article, the atmospheric component of a coupled ensemble forecasting system is evaluated in terms of its ability to provide reasonable forcing to the hydrological component and the effect of the uncertainty represented in the atmospheric ensemble system on the predictability of streamflow as a hydrological variable. The Global Ensemble Forecast System (GEFS) of NCEP is evaluated following a “perfect hydrology” approach, in which its hydrological component, including the Noah land surface model and attached river routing model, is considered free of errors and the initial conditions in the hydrological variables are assumed accurate. The evaluation is performed over the continental United States (CONUS) domain for various sizes of river basins. The results from the experiment suggest that the coupled system is capable of generating useful gridded streamflow forecast when the land surface model and the river routing model can successfully simulate the hydrological processes, and the ensemble strategy significantly improves the forecast. The expected forecast skill increases with increasing size of the river basin. With the current GEFS system, positive skill in short-range (one to three days) predictions can be expected for all significant river basins; for the major rivers with mean streamflow more than 500 m3 s−1, significant skill can be expected from extended-range (the second week) predictions. Possible causes for the loss of skills, including the existence of systematic error and insufficient ensemble spread, are discussed and possible approaches for the improvement of the atmospheric ensemble forecast system are also proposed.
Forecasting Lightning Threat Using Cloud-Resolving Model Simulations
Authors: McCaul Eugene W. , Goodman Steven J. , LaCasse Katherine M. , Cecil Daniel J.
Published: December 2008

Two new approaches are proposed and developed for making time- and space-dependent, quantitative short-term forecasts of lightning threats, and a blend of these approaches is devised that capitalizes on the strengths of each. The new methods are distinctive in that they are based entirely on the ice-phase hydrometeor fields generated by regional cloud-resolving numerical simulations, such as those produced by the Weather Research and Forecasting (WRF) model. These methods are justified by established observational evidence linking aspects of the precipitating ice hydrometeor fields to total flash rates. The methods are straightforward and easy to implement, and offer an effective near-term alternative to the incorporation of complex and costly cloud electrification schemes into numerical models.

One method is based on upward fluxes of precipitating ice hydrometeors in the mixed-phase region at the −15°C level, while the second method is based on the vertically integrated amounts of ice hydrometeors in each model grid column. Each method can be calibrated by comparing domain-wide statistics of the peak values of simulated flash-rate proxy fields against domain-wide peak total lightning flash-rate density data from observations. Tests show that the first method is able to capture much of the temporal variability of the lightning threat, while the second method does a better job of depicting the areal coverage of the threat. The blended solution proposed in this work is designed to retain most of the temporal sensitivity of the first method, while adding the improved spatial coverage of the second.

Simulations of selected diverse North Alabama cases show that the WRF can distinguish the general character of most convective events, and that the methods employed herein show promise as a means of generating quantitatively realistic fields of lightning threat. However, because the models tend to have more difficulty in predicting the instantaneous placement of storms, forecasts of the detailed location of the lightning threat based on single simulations can be in error. Although these model shortcomings presently limit the precision of lightning threat forecasts from individual runs of current generation models, the techniques proposed herein should continue to be applicable as newer and more accurate physically based model versions, physical parameterizations, initialization techniques, and ensembles of forecasts become available.
Effects of Noise and Proficiency on Intelligibility of Chinese-Accented English
Authors: Rogers Catherine L. , Dalby Jonathan , Nishi Kanae
Published: December 2008

This study compared the intelligibility of native and foreign-accented English speech presented in quiet and mixed with three different levels of background noise. Two native American English speakers and four native Mandarin Chinese speakers for whom English is a second language each read a list of 50 phonetically balanced sentences (Egan, 1948). The authors identified two of the Mandarin-accented English speakers as high-proficiency speakers and two as lower proficiency speakers, based on their intelligibility in quiet (about 95% and 80%, respectively). Original recordings and noise-masked versions of 48 utterances were presented to monolingual American English speakers. Listeners were asked to write down the words they heard the speakers say, and intelligibility was measured as content words correctly identified. While there was a modest difference between native and high-proficiency speech in quiet (about 7%), it was found that adding noise to the signal reduced the intelligibility of high-proficiency accented speech significantly more than it reduced the intelligibility of native speech. Differences between the two groups in the three added noise conditions ranged from about 12% to 33%. This result suggests that even high-proficiency non-native speech is less robust than native speech when it is presented to listeners under suboptimal conditions.
Recognition of Spoken Words: Semantic Effects in Lexical Access
Authors: Wurm Lee H. , Vakoch Douglas A. , Seaman Sean R.
Published: December 2008

Until recently most models of word recognition have assumed that semantic effects come into play only after the identification of the word in question. What little evidence exists for early semantic effects in word recognition has relied primarily on priming manipulations using the lexical decision task, and has used visual stimulus presentation. The current study uses auditory stimulus presentation and multiple experimental tasks, and does not use priming. Response latencies for 100 common nouns were found to depend on perceptual dimensions identified by Osgood (1969): Evaluation, Potency, and Activity. In addition, the two-way interactions between these dimensions were significant. All effects were above and beyond the effects of concreteness, word length, frequency, onset phoneme characteristics, stress, and neighborhood density. Results are discussed against evidence from several areas of research suggesting a role of behaviorally important information in perception.
Automatic Discrimination of Emotion from Spoken Finnish
Authors: Toivanen Juhani , Väyrynen Eero , Seppänen Tapio
Published: December 2008

In this paper, experiments on the automatic discrimination of basic emotions from spoken Finnish are described. For the purpose of the study, a large emotional speech corpus of Finnish was collected; 14 professional actors acted as speakers, and simulated four primary emotions when reading out a semantically neutral text. More than 40 prosodic features were derived and automatically computed from the speech samples. Two application scenarios were tested: the first scenario was speaker-independent for a small domain of speakers while the second scenario was completely speaker-independent. Human listening experiments were conducted to assess the perceptual adequacy of the emotional speech samples. Statistical classification experiments indicated that, with the optimal combination of prosodic feature vectors, automatic emotion discrimination performance close to human emotion recognition ability was achievable.
Interaction of Native- and Second-Language Vowel System(s) in Early and Late Bilinguals
Authors: Baker Wendy , Trofimovich Pavel
Published: December 2008

The objective of this study was to determine how bilinguals' age at the time of language acquisition influenced the organization of their phonetic system(s). The productions of six English and five Korean vowels by English and Korean monolinguals were compared to the productions of the same vowels by early and late Korean-English bilinguals varying in amount of exposure to their second language. Results indicated that bilinguals' age profoundly influenced both the degree and the direction of the interaction between the phonetic systems of their native (L1) and second (L2) languages. In particular, early bilinguals manifested a bidirectional L1-L2 influence and produced distinct acoustic realizations of L1 and L2 vowels. Late bilinguals, however, showed evidence of a unidirectional influence of the L1 on the L2 and produced L2 vowels that were “colored” by acoustic properties of their L1. The degree and direction of L1-L2 influences in early and late bilinguals appeared to depend on the degree of acoustic similarity between L1 and L2 vowels and the length of their exposure to the L2. Overall, the findings underscored the complex nature of the restructuring of the L1-L2 phonetic system(s) in bilinguals.
Sociolinguistic Competence in the Complimenting Act of Native Chinese and American English Speakers: A Mirror of Cultural Value
Authors: Yu Ming-chung
Published: December 2008

The present study examines sociolinguistic features of a particular speech act, paying compliments, by comparing and contrasting native Chinese and native American speakers' performances. By focusing on a relatively understudied speaker group such as the Chinese, typically regarded as having rules of speaking and social norms very different from those of Westerners, this paper aims at illuminating the fact that, in cross-cultural communication, foreign language speakers have to pay close attention to sociolinguistic rules of the target language in addition to structure and discourse rules to meet the needs of linguistic accuracy and fluency. This is due to the fact that such rules play an indispensable role in appropriating the proper use of linguistic forms. The data for this study were collected using ethnographic observation pioneered in this field by Wolfson and Manes (1980). The analysis will first explore both the features of distribution of paying compliments, and the functions they may serve in spoken exchanges for native Chinese and American English speakers. To present a fuller picture of the socio-cultural features this speech act may represent in Chinese and American societies, the analysis will further focus on the issues of topics, the addresser-addressee relationship, and culture-specificity versus universality.