bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydroxyapatite formed on/in agarose gel induces activation of blood coagulation and platelets aggregation
Authors: Arimura Shin‐ichiro , Kawahara Ko‐ichi , Biswas Kamal Krishna , Abeyama Kazuhiro , Tabata Masashi , Shimoda Toru , Ogomi Daisuke , Matsusaki Michiya , Kato Shinya , Ito Takashi , Sugihara Kazumasa , Akashi Mitsuru , Hashiguchi Teruto , Maruyama Ikuro
Published: October 2006

We reported earlier that hydroxyapatite (HA) formed on/in agarose gels (HA/agarose) produced by alternate soaking process is a bone‐filling material possessing osteoconductive and hemostatic effects. This process could allow us to make bone‐like apatite that was formed on/in organic polymer hydrogel matrices. Here, we investigated the mechanism of hemostasis induced by HA/agarose and found that HA/agarose, but not agarose or HA powder, significantly shortened activated partial thromboplastin time (APTT). While HA/agarose did not show significant platelet aggregation, it markedly enhanced adenosine diphosphate (ADP)‐induced platelet aggregation. Moreover, Western blot analysis revealed selective adsorption of vitronectin onto HA/agarose. We also observed marked differences between HA powder and HA/agarose in their XRD patterns. The crystallinity of HA powder was much higher compared to that of HA/agarose. Furthermore, 50–100 nm of tube‐form aggregations was observed in HA powder on the other hand 100–200 nm of particles was observed in HA/agarose by SEM observation. Thus 100–200 nm of low crystallized particles on the surface structure of HA/agarose may play an important role in hemostasis. Our results demonstrated a crucial role of HA/agarose in the mechanism of hemostasis and suggested a potential role for HA/agarose as a bone‐grafting material. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Hydration and carbonation of monoclinic C2S and C3S studied by Raman spectroscopy
Authors: Ibáñez Jordi , Artús Lluís , Cuscó Ramon , López Ángel , Menéndez Esperanza , Andrade María C.
Published: October 2006

We present a micro‐Raman study on the hydration and carbonation of the main silicate phases of Portland cement, i.e. monoclinic dicalcium silicate (C2S) and monoclinic tricalcium silicate (C3S). We investigate the reaction products and the loss of crystallinity induced by hydration on these two compounds. In the CO2‐contaminated pastes we find that calcite, aragonite, and vaterite are inhomogeneously formed. We study sample cross sections to evaluate the maximum depth at which CaCO3 is formed. We find that carbonation is limited to the first 500–1000 µm from the surface in the C3S pastes, while in C2S pastes CaCO3 is formed well beyond this depth. Our results show the great potential of Raman spectroscopy in the study of the chemistry of cements. Copyright © 2006 John Wiley & Sons, Ltd.
Effect of lanthanum substitution on the Raman spectra of barium titanate thin films
Authors: Dobal P. S. , Dixit A. , Katiyar R. S.
Published: October 2006

Thin films of Ba1−xLaxTiO3 on platinum substrates were synthesized using the sol–gel method for x values of 0.0, 0.03, 0.05, and 0.10, and the effect of trivalent La3+ substitution on the structural and dielectric properties was studied. Using X‐ray diffraction, structural analysis of these compositions revealed a slight increase in the tetragonal distortion of the unit cell with increase in La content. Accordingly, an increase in the tetragonal to cubic transition temperature TT/C was detected by temperature‐dependent Raman spectroscopy in the range of 70–500 K. Unlike the results from Raman scattering for the La‐doped BaTiO3 films, the dielectric measurements showed broad and diffused dielectric maxima, making the estimation of the transition temperature merely qualitative. Copyright © 2006 John Wiley & Sons, Ltd.
Integrated processing of fresh Indian sea buckthorn (Hippophae rhamnoides) berries and chemical evaluation of products
Authors: Arimboor Ranjith , Venugopalan VV , Sarinkumar K , Arumughan C , Sawhney Ramesh Chand
Published: October 2006

An efficient pilot‐scale process was developed to produce nutraceutical products from fresh sea buckthorn (Hippophae rhamnoides) berries. Fresh berries were subjected to high‐pressure dewatering using a continuous screw press. The separated liquid phase containing 80–90% of pulp oil was clarified at 80 °C and centrifuged to obtain pulp oil, clear juice and sludge. The pulp oil yield was 2.7–2.8% of fresh berry weight with 66–70% extraction efficiency. The pulp oil was remarkably rich in carotenoids (2450–2810 mg kg−1), tocopherols (1409–1599 mg kg−1) and sterols (4096–4403 mg kg−1), with a characteristic fresh berry flavour and 16:1 as the major fatty acid (45.6–49.1%). The clear juice obtained was free from oil and contained high amounts of vitamin C (1683–1840 mg kg−1) and phytochemicals such as polyphenols (2392–2821 mg kg−1) and flavonoids (340–401 mg kg−1). Isorhamnetin (251–310 mg kg−1) was the major flavonoid in the juice, along with quercetin (77–81 mg kg−1) and kaempherol (12–16 mg kg−1). The juice was very acidic (pH 3), with high concentrations of organic acids (30.8–36.0 g kg−1). High‐performance liquid chromatography profiling of organic acids revealed quinic acid (18.1–19.9 g kg−1) as the major acid in the juice. The seeds in the pressed cake were separated and extracted for oil using supercritical CO2. Copyright © 2006 Society of Chemical Industry
Bioequivalence of β‐carotene and retinol
Authors: Thurnham David I
Published: October 2006

For many years it was accepted that 6 mg of β‐carotene were required to produce 1 mg of vitamin A in the form of retinol. The equivalence was based on the assumptions that two‐thirds of dietary β‐carotene are not absorbed, while in the metabolism of the remaining third 1 mol of β‐carotene is converted to 1 mol retinol. Recently, the bioequivalence was raised to 12 mg β‐carotene and 1 mg retinol. The objective of this review was to re‐examine the data that were used to support the new equivalence ratio, especially since some of these data were obtained in developing countries where infestation with gut parasites and exposure to other infections is common, yet the influence of inflammation on plasma carotenoid and retinol concentrations is frequently ignored. Bioequivalence studies examined in this review include those done in developing and developed countries, depletion and repletion studies, feeding with vegetable sources of β‐carotene or pure supplements, influence of helminths, carotenoid interactions and matrix effects and studies using stable isotopes (SI). SI studies show the bioefficacy of β‐carotene conversion to retinol is generally poor even for pure β‐carotene unless the dose is small and fed regularly until equilibration is reached. Retinol formation appears to be inversely influenced by previous vitamin A intake, the amount of material given and current vitamin A status. In spite of technical complexities, more SI studies where liver reserves of vitamin A are determined pre and post intervention are needed to evaluate β‐carotene bioefficacy of different vegetable sources. Copyright © 2006 Society of Chemical Industry
Effect of immersion and turgor pressure change on mechanical properties of pumpkin (Cucumis moschata, Duch.)
Authors: de Escalada Pla Marina , Delbon Marisa , Rojas Ana M , Gerschenson Lia N
Published: October 2006

Mesocarp raw tissue of a pumpkin (Cucumis moschata, Duch.) popularly known in Argentina as ‘calabacita criolla’ was rheologically characterized by large and small deformations after a stepwise adjustment of its turgor pressure to determine the relative contributions of turgor pressure, cell wall (CW) and middle lamella (ML) to the mechanical behavior. Examinations using light microscopy (LM) and transmission electron microscopy (TEM) were performed in order to explain the textural behavior observed. In general, firmness at failure, residual relaxation force and dynamic moduli increased with turgor pressure. For all the hypotonic solutions (polyethylene glycol 400 (PEG) concentrations lower than 250 mol m−3) a gain of tissue weight was observed, a trend that indicated a null occurrence of cell bursting as confirmed by observations using LM and TEM of undamaged cell membranes with swelled cytoplasms. However, no significative change in relative volume was detected for tissue equilibrated in PEG with concentrations of 0–130 mol m−3, probably due to the resistance of CW to further elongation. Peaks of failure were observed during compression for tissue equilibrated under all osmotic conditions and their presence was associated with CW integrity. Plasmolysed tissue did not show a residual force at infinite time of relaxation. Incipient plasmolysis was better detected by rheological studies than by volume change and it was confirmed by LM. Significant correlations were obtained between residual relaxation force and either storage moduli or phase shift angle, revealing that relaxation out of the linear viscoelasticity range and dynamic assays provide analogous information concerning tissue behavior. Copyright © 2006 Society of Chemical Industry
Dietary flavonoids: effects on endothelial function and blood pressure
Authors: Hodgson Jonathan M , Croft Kevin D
Published: October 2006

Several population studies have found an inverse association between flavonoid intake and risk of cardiovascular disease. These studies have resulted in the hypothesis that dietary flavonoids protect against cardiovascular disease. Manyin vitrostudies, studies using animal models and human intervention trials have been carried out to investigate how flavonoids might provide protection. Emerging and largely consistent evidence suggests that flavonoids can improve endothelial function and may reduce blood pressure.In vitrostudies show that a variety of flavonoids cause vasorelaxation of isolated arteries from rats. In human intervention trials, flavonoids derived from tea and cocoa or dark chocolate—both rich sources of catechins—have been found to improve endothelial function acutely and with regular ingestion. The evidence for benefits of flavonoids from other dietary sources is less clear. Improvements in endothelial function could contribute to lower blood pressure. Population studies have associated higher intake of tea and chocolate with lower blood pressure. Short‐term intervention studies in humans have shown blood pressure lowering with cocoa or dark chocolate, but short‐term regular ingestion of tea has not been found to lower blood pressure. The long‐term effects of regular ingestion of a flavonoid‐enriched diet on endothelial function and blood pressure have yet to be assessed. In addition, there is evidence that flavonoid metabolism is an important factor influencing the biological activity and effects of dietary flavonoids, but further studies are needed to investigate this area. Copyright © 2006 Society of Chemical Industry
Number of non‐Fregean sentential logics that have adequate models
Authors: Golińska‐Pilarek Joanna
Published: October 2006

We show that there are continuum many different non‐Fregean sentential logics that have adequate models. The proof is based on the construction of a special class of models of the power of the continuum. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cationic liposomes as non‐viral carriers of gene medicines: Resolved issues, open questions, and future promises
Authors: Karmali Priya Prakash , Chaudhuri Arabinda
Published: October 2006

The clinical success of gene therapy is critically dependent on the development of efficient and safe gene delivery reagents, popularly known as “transfection vectors.” The transfection vectors commonly used in gene therapy are mainly of two types: viral and non‐viral. The efficiencies of viral transfection vectors are, in general, superior to their non‐viral counterparts. However, the myriads of potentially adverse immunogenic aftermaths associated with the use of viral vectors are increasingly making the non‐viral gene delivery reagents as the vectors of choice. Among the existing arsenal of non‐viral gene delivery reagents, the distinct advantages associated with the use of cationic transfection lipids include their: (a) robust manufacture; (b) ease in handling and preparation techniques; (c) ability to inject large lipid:DNA complexes; and (d) low immunogenic response. The present review highlights the major achievements in the area of designing efficacious cationic transfection lipids, some of the more recent advances in the field of cationic liposomes‐mediated gene transfer and targeted gene delivery, some unresolved issues and challenges in liposomal gene delivery, and future promises of cationic liposomes as gene‐carriers in non‐viral gene therapy. © 2006 Wiley Periodicals, Inc. Med Res Rev, 27, No. 5, 696–722, 2007
Crystal structures of vegetative soybean lipoxygenase VLX‐B and VLX‐D, and comparisons with seed isoforms LOX‐1 and LOX‐3
Authors: Youn Buhyun , Sellhorn George E. , Mirchel Ryan J. , Gaffney Betty J. , Grimes Howard D. , Kang ChulHee
Published: October 2006

The lipoxygenase family of lipid‐peroxidizing, nonheme iron dioxygenases form products that are precursors for diverse physiological processes in both plants and animals. In soybean (Glycine max), five vegetative isoforms, VLX‐A, VLX‐B, VLX‐C, VLX‐D, VLX‐E, and four seed isoforms LOX‐1, LOX‐2, LOX‐3a, LOX‐3b have been identified. In this study, we determined the crystal structures of the substrate‐free forms of two major vegetative isoforms, with distinct enzymatic characteristics, VLX‐B and VLX‐D. Their structures are similar to the two seed isoforms, LOX‐1 and LOX‐3, having two domains with similar secondary structural elements: a β‐barrel N‐terminal domain containing highly flexible loops and an α‐helix‐rich C‐terminal catalytic domain. Detailed comparison of the structures of these two vegetative isoforms with the structures of LOX‐1 and LOX‐3 reveals important differences that help explain distinct aspects of the activity and positional specificity of these enzymes. In particular, the shape of the three branches of the internal subcavity, corresponding to substrate‐binding and O2 access, differs among the isoforms in a manner that reflects the differences in positional specificities. Proteins 2006. © 2006 Wiley‐Liss, Inc.
A new cell‐permeable calpain inhibitor
Authors: Fiorino Ferdinando , Gil‐Parrado Shirley , Assfalg‐Machleidt Irmgard , Machleidt Werner , Moroder Luis
Published: October 2006

The ubiquitous calpains, µ‐ and m‐calpain, are implicated in a variety of vital (patho)physiological processes and therefore cell‐permeable specific inhibitors represent important tools for defining the role of calpains in cells and animal models. A synthetic N‐acetylated 27‐mer peptide derived from exon B of the human calpastatin inhibitory domain 1 is known to be the most potent and selective reversible inhibitor of calpains. To improve the membrane permeability of this peptidic inhibitor, it was N‐terminally extended with or disulfide‐linked to the C‐terminal 7‐mer fragment of penetratin, a well‐established vector for cell membrane translocation of bioactive compounds. Despite the shorter penetratin sequence, both constructs showed increased cell permeability and retained their full calpain inhibitory potency. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd.
On the PL, TSL and OSL properties of SrS:Ce,Sm phosphor
Authors: Lapraz Dominique , Prévost Hildegarde , Idri Katia , Angellier Gaëlle , Dusseau Laurent
Published: October 2006

The photoluminescence (PL), thermostimulated luminescence (TSL) and optical stimulated luminescence (OSL) properties of a cerium and samarium codoped strontium sulfide (SrS:Ce,Sm) used in OSL imaging devices are studied after UV or X‐ray irradiation. A correlation is made between TSL and OSL results, showing a strong thermal and optical fading at room temperature, implying a significant instability of the OSL signal. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of samarium doping on electrodeposited CeO2 thin film
Authors: Phok Sovannary , Bhattacharya Raghu N.
Published: October 2006

Samarium‐doped cerium oxide (CeO2:Sm) and undoped cerium oxide (CeO2) thin films were fabricated by electrodeposition on biaxially textured Ni–3% W substrates. The electrodeposited layers were annealed for several hours at temperatures ranging from 910 to 980 °C. The resulting crystalline films were investigated by XRD and SEM. The CeO2 crystallite size was correlated to the formation of microcrack in CeO2 and CeO2:Sm using the Scherrer equation of XRD analysis. Crack‐free films with an average grain size of about 28 nm were obtained for both Ce0.92Sm0.08O2–δ and Ce0.8Sm0.2O2–δ films. Sm doping strongly affects the crystallite size, crystal structure, texture, and crack formation in ceria films. The lattice parameter a increases and crystallite size is reduced with increased Sm doping. All electrodeposited films are highly biaxially textured. When compared to Ni‐based substrates, improvements in the out‐of‐plane and in‐plane texture in ceria‐ and Sm‐doped ceria films were achieved. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Small Molecule Microarrays: Applications Using Specially Tagged Chemical Libraries
Authors: Wang Jun , Uttamchandani Mahesh , Sun Hongyan , Yao Shao Q.
Published: October 2006

Recent advances in proteomics and combinatorial synthesis have drawn impetus towards the development of robust technologies for the convenient identification of biologically relevant entities from within diverse chemical sets, as well as rapid strategies for the functional profiling of proteins. Amongst the various exciting platforms that have been developed to address these challenges, spatially addressable microarrays of small molecules have emerged as a versatile, high‐density platform for high‐throughput screening and analysis. The fabrication process of small molecule microarray demands that diverse molecular species and scaffolds be presented suitably for parallel screening, thereby necessitating unique design and synthetic considerations, particularly in the generation of specialized tags for encoded capture or immobilization on complementary surfaces. Of significance are the strategies that have been established to assemble organized assortments of compounds according to the downstream application requirements on microarrays. Many creative ideas have taken the technology well beyond its initial utility in lead discovery and molecular characterization, to cell‐based screenings as well as protein characterization and fingerprinting. The increasing ease and expanding scale of chemical library creation, combined with the massive screening throughput offered, heralds great promise for SMM, which is set to take on wider applications in discovery, diagnostics and medicine.
Reproducibility of the measurement of submucous fibroid protrusion into the uterine cavity using three‐dimensional saline contrast sonohysterography
Authors: Lee C. , Salim R. , Ofili‐Yebovi D. , Yazbek J. , Davies A. , Jurkovic D.
Published: October 2006

Objective

To determine the intraobserver and interobserver reproducibility of measurement of the percentage of protrusion of submucous fibroids into the uterine cavity using three‐dimensional saline contrast sonohysterography (3D‐SCSH).

Methods

Women diagnosed with submucous uterine fibroids on B‐mode two‐dimensional (2D) ultrasound scan were invited to join the study and 3D‐SCSH was carried out. 3D volume datasets were stored digitally and were examined later using the technique of planar reformatted sections. The reproducibilities of the measurement of fibroid diameter and protrusion ratio into the uterine cavity (ratio of the size of the segment of the fibroid protruding into the cavity to the total diameter of the fibroid) were examined by two independent observers who were unaware of the initial 2D scan findings. Interobserver reproducibility was assessed by calculating the difference between measurements taken by the two operators (limits of agreement) and interclass correlation coefficient. Intraobserver repeatability was assessed by calculating the difference between two measurements for each variable (limits of agreement) and further expressed as an intraclass correlation coefficient.

Results

Thirty‐three 3D ultrasound volumes were examined. There was a good agreement between the observers in classifying the fibroids as greater or less than 50% confined to the myometrium (Cohen's kappa 0.81). There was no bias in measurements for both variables either between observers or with repeated measurements by each observer. For fibroid diameter and protrusion ratio the inter‐ and intraclass correlation coefficients were high (0.984–0.995), with narrow limits of agreement.

Conclusion

3D‐SCSH is a reproducible method for the quantification of the percentage of a submucous fibroid protruding into the uterine cavity. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Current source density analysis of contra- and ipsilateral
isthmotectal connections of the frog
Authors: HOSHINO NORIAKI , TSURUDOME KAZUYA , NAKAGAWA HIDEKI , MATSUMOTO NOBUYOSHI
Published: October 2006

The nucleus isthmi (NI) of the frog receives input from the
ipsilateral optic tectum and projects back to both optic tecta. After
ablation of NI, frogs display no visually elicited prey-catching or threat
avoidance behavior. Neural mechanisms that underlie the loss of such
important behavior have not been solved. Electrophysiological examination
of the contralateral isthmotectal projection has proved that it
contributes to binocular vision. On the other hand, there are very few
physiological investigations of the ipsilateral isthmotectal projection.
In this study, current source density (CSD) analysis was applied to
contra- and ipsilateral isthmotectal projections. The contralateral
projection produced monosynaptic sinks in superficial layers and in layer
8. The results confirmed former findings obtained by single unit
recordings. The ipsilateral projection elicited a prominent monosynaptic
sink in layer 8. Recipient neurons were located in layers 6–7. These
results, combined with those from the former intracellular study, led to
the following neuronal circuit. Afferents from the ipsilateral NI inhibit
non-efferent pear shaped neurons in the superficial layers, and strongly
excite large ganglionic neurons projecting to the descending motor
regions. Thus feedback to the output neurons strengthens the visually
elicited responses.
Dissociated GABAergic retinal interneurons exhibit spontaneous increases in intracellular calcium
Authors: FIRTH SALLY I. , FELLER MARLA B.
Published: October 2006

Early in development, before the retina is responsive to light, neurons exhibit spontaneous activity. Recently it was demonstrated that starburst amacrine cells, a unique class of neurons that secretes both GABA and acetylcholine, spontaneously depolarize. Networks comprised of spontaneously active starburst cells initiate correlated bursts of action potentials that propagate across the developing retina with a periodicity on the order minutes. To determine whether other retinal interneurons have similar “pacemaking” properties, we have utilized cultures of dissociated neurons from the rat retina. In the presence of antagonists for fast neurotransmitter receptors, distinct populations of neurons exhibited spontaneous, uncorrelated increases in intracellular calcium concentration. These increases in intracellular calcium concentration were sensitive to tetrodotoxin, indicating they are mediated by spontaneous membrane depolarizations. By combining immunofluorescence and calcium imaging, we found that 44% of spontaneously active neurons were GABAergic and included starburst amacrine cells. Whole cell voltage clamp recordings in the absence of antagonists for fast neurotransmitters revealed that after 7 days in culture, individual retinal neurons receive bursts of GABA-A receptor mediated synaptic input with a periodicity similar to that measured in spontaneously active GABAergic neurons. Low concentrations of GABA-A receptor antagonists did not alter the inter-burst interval despite significant reduction of post-synaptic current amplitude, indicating that pacemaker activity of GABAergic neurons was not influenced by network interactions. Together, these findings indicate that spiking GABAergic interneurons can function as pacemakers in the developing retina.
In vivodevelopment of retinal ON-bipolar cell axonal terminals visualized innyx::MYFPtransgenic zebrafish
Authors: SCHROETER ERIC H. , WONG RACHEL O.L. , GREGG RONALD G.
Published: October 2006

Axonal differentiation of retinal bipolar cells has largely been studied by comparing the morphology of these interneurons in fixed tissue at different ages. To better understand how bipolar axonal terminals developin vivo, we imaged fluorescently labeled cells in the zebrafish retina using time-lapse confocal and two photon microscopy. Using the upstream regulatory sequences from thenyxgene that encodes nyctalopin, we constructed a transgenic fish in which a subset of retinal bipolar cells express membrane targeted yellow fluorescent protein (MYFP). Axonal terminals of these YFP-labeled bipolar cells laminated primarily in the inner half of the inner plexiform layer, suggesting that they are likely to be ON-bipolar cells. Transient expression of MYFP in isolated bipolar cells indicates that two or more subsets of bipolar cells, with one or two terminal boutons, are labeled. Live imaging of YFP-expressing bipolar cells in thenyx::MYFPtransgenic fish at different ages showed that initially, filopodial-like structures extend and retract from their primary axonal process throughout the inner plexiform layer (IPL). Over time, filopodial exploration becomes concentrated at discrete foci prior to the establishment of large terminal boutons, characteristic of the mature form. This sequence of axonal differentiation suggests that synaptic targeting by bipolar cell axons may involve an early process of trial and error, rather than a process of directed outgrowth and contact. Our observations represent the firstin vivovisualization of axonal development of bipolar cells in a vertebrate retina.
Modulation of A-type potassium currents in retinal horizontal cells
by extracellular calcium and zinc
Authors: ZHANG DAO-QI , SUN ZIYI , MCMAHON DOUGLAS G.
Published: October 2006

Extracellular Ca2+ and Zn2+ influence many
aspects of retinal function. Here, we examined the effect of external
Ca2+ and Zn2+ on potassium channels of retinal
horizontal cells. When extracellular Ca2+ was lowered from 3 mM
to 0.3 mM, horizontal cell transient outward currents elicited by voltage
steps from resting membrane potential (−70 mV) were decreased by
approximately 50%, whereas the sustained currents remained unchanged. This
effect was due to a hyperpolarizing shift in the steady-state inactivation
curve of A-type K+ currents when extracellular Ca2+
concentration was lowered. The mean half inactivation potential of the
steady-state inactivation curves was hyperpolarized from −56.3
± 4.7 mV in 3 mM Ca2+ to −76.4 ± 3.9 mV in
0.3 mM Ca2+. Neither the state-steady activation curve nor the
kinetics of inactivation was significantly changed in low extracellular
Ca2+. The addition of 30 μM Zn2+ restored peak
outward currents in 0.3 mM Ca2+. The half inactivation voltages
were depolarized from −70 ± 2.8 mV in 0.3 mM Ca2+
to −56 ± 2.6 mV in 0.3 mM Ca2+ plus 30 μM
Zn2+. Taken together, the results indicate that external
Ca2+ and Zn2+ maintain the activity of A-type
potassium channels in retinal horizontal cells by influencing the voltage
dependence of steady-state inactivation.
Studies of ELF propagation in the spherical shell cavity using a field decomposition method based on asymmetry of Schumann resonance curves
Authors: Kułak A. , Młynarczyk J. , Zięba S. , Micek S. , Nieckarz Z.
Published: October 2006

Asymmetric resonance curves are observed in various resonance systems occurring in nature. The reason for such a shape of the resonance curves is an interaction of the standing waves field in the resonator with the field of traveling waves which transmit energy from sources to the resonator. This behavior can be observed in strongly damped electromagnetic resonators. The ELF wave propagation inside the Earth‐ionosphere cavity is a good example of the simultaneous occurrence of resonance and transmission phenomena. In this paper we show that the transmission field component depends on the attenuation rate of the Earth‐ionosphere cavity and the observer‐source distance. Besides, the resonance curve asymmetry causes an evident diurnal variability of the resonance frequencies. The superposition of the two components at any point of the resonator makes the analysis of the Schumann resonance (SR) difficult. Here we suggest a field decomposition method that allows separating the resonance component from the transmission one. Owing to the decomposition, having a single measurement of the E or B field, it is possible, independently of the observer position, to study the physical properties of the resonator as well as to determine the localization and the intensity of sources. The field decomposition permits defining new resonator parameters such as reduced resonance frequencies and reduced quality factors, independent of the observer position inside the cavity. We believe that the application of the decomposition method in the analysis of the ELF observations yields a possibility of improving the accuracy of the determination of both the distances and intensities of the sources exciting the Earth‐ionosphere resonator, as well as its own parameters.
On the short‐term relationship between solar soft X‐ray irradiances and equatorial total electron content (TEC)
Authors: Wang X. , Eastes R. , Weichecki Vergara S. , Bailey S. , Valladares C. , Woods T.
Published: October 2006

The relationship between total electron content (TEC) and the solar soft X‐ray irradiances is presented. Three bands (2–7 nm, 6–19 nm, and 17–20 nm) of solar soft X‐ray measurements from the Student Nitric Oxide Explorer (SNOE) satellite are examined and all show a similar relationship with TEC. The TEC data are from a GPS receiver near Ancon, Peru (−11.78 degrees latitude, −77.15 degrees longitude) from 11 March 1998 to 23 August 1999 and 2 October 1999 to 10 June 2000. During these periods the average TEC measurement was calculated from all observations whose ionospheric pierce point occurred within −12 ± 2 degrees latitude and −77 ± 2 degrees longitude and within the hour selected. TEC shows a more significant correlation with soft X‐ray irradiances than with F10.7. The X rays lead the TEC by approximately 0.8–1.3 days, which is consistent with the neutral density affecting the TEC. The magnitude of these short term (27 days or less) changes is approximately 0.18 of the total TEC. During the period examined geomagnetic activity, as represented by Ap, could account for half as much variation in TEC (0.1 of the total TEC) as the solar irradiance.
Impact of microbial growth on water flow and solute transport in unsaturated porous media
Authors: Yarwood R. R. , Rockhold M. L. , Niemet M. R. , Selker J. S. , Bottomley P. J.
Published: October 2006

A novel analytical method was developed that permitted real‐time, noninvasive measurements of microbial growth and associated changes in hydrodynamic properties in porous media under unsaturated flowing conditions. Salicylate‐induced, lux gene‐based bioluminescence was used to quantify the temporal and spatial development of colonization over a 7‐day time course. Water contents were determined daily by measuring light transmission through the system. Hydraulic flow paths were determined daily by pulsing a bromophenol blue dye solution through the colonized region of the sand. Bacterial growth and accumulation had a significant impact on the hydraulic properties of the porous media. Microbial colonization caused localized drying within the colonized zone, with decreases in saturation approaching 50% of antecedent values, and a 25% lowering of the capillary fringe height. Flow was retarded within the colonized zone and diverted around it concurrent with the expansion of the colonized zone between days 3 and 6. The location of horizontal dispersion corresponded with the cell densities of 1–3 × 109 cells g−1 dry sand. The apparent solute velocity through the colonized region was reduced from 0.41 cm min−1 (R2 = 0.99) to 0.25 cm min−1 (R2 = 0.99) by the sixth day of the experiment, associated with population densities that would occupy approximately 7% of the available pore space within the colonized region. Changes in the extent of colonization occurred over the course of the experiment, including upward migration against flow. The distribution of cells was not determined by water flow alone, but rather by a dynamic interaction between water flow and microbial growth. This experimental system provides rich data sets for the testing of conceptualizations expressed through numerical modeling.
Reconstructing the weather on Mars at the time of the MERs and Beagle 2 landings
Authors: Montabone L. , Lewis S. R. , Read P. L. , Withers P.
Published: October 2006

We reconstruct the temperature, wind and density structure of the atmosphere on Mars from the surface to 120 km altitude at the time of the landing of the two NASA Mars Exploration Rovers (MER), and ESA's “Beagle 2.” This reconstruction is based on an assimilation of temperature and dust opacity observations from the Thermal Emission Spectrometer aboard the Mars Global Surveyor spacecraft into a general circulation model of the Martian atmosphere and, for the case of the MERs, on retrievals of temperature and density profiles from accelerometer data. For all landers, the reconstruction of the atmospheric state is compared with the climatological state predicted by the European Mars Climate Database (EMCD) for two different prescribed dust scenarios, with added large‐ and small‐scale variability. This comparison exhibits good agreement for all three landers within the modeled variability, confirming a posteriori the accuracy of the climate forecasts by the EMCD.
Ensemble hindcasts of SST anomalies in the tropical Pacific using an intermediate coupled model
Authors: Zheng Fei , Zhu Jiang , Zhang Rong‐Hua , Zhou Guang‐Qing
Published: October 2006

Ensemble hindcasts of sea surface temperature (SST) anomalies in the tropical Pacific are studied using an intermediate coupled model (ICM), in which an ensemble Kalman filter (EnKF) data assimilation system is implemented to provide the initial ensemble. A linear, first‐order Markov stochastic model is adopted to represent model errors. Parameters in the stochastic model are estimated by comparing observation‐minus‐forecast values over 30 years. Twelve‐month, 120 ensemble hindcasts are performed over the period 1995–2004, each with 100 ensemble members. This ensemble technique provides a simple method of extending the standard ICM forecasts to the probabilistic domain. The results show that the prediction skill of the ensemble mean is better than that of one single deterministic forecast using the same ICM. For the probabilistic perspective, those ensemble forecasts have their ensembles following observed SST anomaly variations well.
Global relationships of total alkalinity with salinity and temperature in surface waters of the world's oceans
Authors: Lee Kitack , Tong Lan T. , Millero Frank J. , Sabine Christopher L. , Dickson Andrew G. , Goyet Catherine , Park Geun‐Ha , Wanninkhof Rik , Feely Richard A. , Key Robert M.
Published: October 2006

A simple function of sea surface salinity (SSS) and temperature (SST) in the form AT=a+b(SSS − 35) +c(SSS − 35)2+d(SST − 20) +e(SST − 20)2fits surface total alkalinity (AT) data for each of five oceanographic regimes within an area‐weighted uncertainty of ±8.1μmol kg−1(1σ). Globally coherent surface ATdata (n = 5,692) used to derive regional correlations of ATwith SSS and SST were collected during the global carbon survey in the 1990s. Such region‐specific ATalgorithms presented herein enable the estimation of the global distribution of surface ATwhen observations of SSS and SST are available.
Evidence for rainfall‐triggered earthquake activity
Authors: Hainzl S. , Kraft T. , Wassermann J. , Igel H. , Schmedes E.
Published: October 2006

Fluids are known to be of major importance for the earthquake generation because pore pressure variations alter the strength of faults. Thus they can initiate earthquakes if the crust is close enough to its critical state. Based on the observations of the isolated seismicity below the densely monitored Mt. Hochstaufen, SE Germany, we are now able to demonstrate that the crust can be so close‐to‐failure that even tiny pressure variations associated with precipitation can trigger earthquakes in a few kilometer depth. We find that the recorded seismicity is highly correlated with the calculated spatiotemporal pore pressure changes due to diffusing rain water and in good agreement with the response of faults described by the rate‐state friction law.
Parallel proton fire hose instability in the expanding solar wind: Hybrid simulations
Authors: Matteini Lorenzo , Landi Simone , Hellinger Petr , Velli Marco
Published: October 2006

We report a study of the properties of the parallel proton fire hose instability comparing the results obtained by the linear analysis, from one‐dimensional (1‐D) standard hybrid simulations and 1‐D hybrid expanding box simulations. The three different approaches converge toward the same instability threshold condition which is in good agreement with in situ observations, suggesting that such instability is relevant in the solar wind context. We investigate also the effect of the wave‐particle interactions on shaping the proton distribution function and on the evolution of the spectrum of the magnetic fluctuations during the expansion. We find that the resonant interaction can provide the proton distribution function to depart from the bi‐Maxwellian form.
Self‐consistent model of magnetospheric ring current and propagating electromagnetic ion cyclotron waves: Waves in multi‐ion magnetosphere
Authors: Khazanov G. V. , Gamayunov K. V. , Gallagher D. L. , Kozyra J. U.
Published: October 2006

The further development of a self‐consistent theoretical model of interacting ring current ions and electromagnetic ion cyclotron waves (Khazanov et al., 2003) is presented. In order to adequately take into account wave propagation and refraction in a multi‐ion magnetosphere, we explicitly include the ray tracing equations in our previous self‐consistent model and use the general form of the wave kinetic equation. This is a major new feature of the present model and, to the best of our knowledge, the ray tracing equations for the first time are explicitly employed on a global magnetospheric scale in order to self‐consistently simulate the spatial, temporal, and spectral evolution of the ring current and of electromagnetic ion cyclotron waves. To demonstrate the effects of EMIC wave propagation and refraction on the wave energy distribution and evolution, we simulate the May 1998 storm. The main findings of our simulation can be summarized as follows. First, owing to the density gradient at the plasmapause, the net wave refraction is suppressed, and He+‐mode grows preferably at the plasmapause. This result is in total agreement with previous ray tracing studies and is very clearly found in presented B field spectrograms. Second, comparison of global wave distributions with the results from another ring current model (Kozyra et al., 1997) reveals that this new model provides more intense and more highly plasmapause‐organized wave distributions during the May 1998 storm period. Finally, it is found that He+‐mode energy distributions are not Gaussian distributions and most important that wave energy can occupy not only the region of generation, i.e., the region of small wave normal angles, but all wave normal angles, including those to near 90°. The latter is extremely crucial for energy transfer to thermal plasmaspheric electrons by resonant Landau damping and subsequent downward heat transport and excitation of stable auroral red arcs.
Condensation of water vapor: Experimental determination of mass and thermal accommodation coefficients
Authors: Winkler P. M. , Vrtala A. , Rudolf R. , Wagner P. E. , Riipinen I. , Vesala T. , Lehtinen K. E. J. , Viisanen Y. , Kulmala M.
Published: October 2006

Experimental determinations of mass and thermal accommodation coefficients αm and αt for condensation of water vapor in air have been conducted covering a temperature range from about 250 to 290 K. For the first time, both coefficients have been determined directly and simultaneously. To this end, growth of water droplets in air has been observed at different total gas pressures ranging from about 1000 down to 100 hPa. Monodispersed seed particles have been used as condensation nuclei. After addition of water vapor with well‐defined partial vapor pressure, supersaturation was achieved by adiabatic expansion in an expansion chamber. Most experiments reported in the present paper were performed at vapor saturation ratios ranging from 1.30 to 1.50. Monodispersed Ag particles with a diameter of 9 nm have been used as condensation nuclei, and for humidification a diffusion humidifier was applied. One experiment was performed at the saturation ratio of 1.02, which resembles conditions observed in the Earth's lower atmosphere. In this experiment, monodispersed DEHS particles with a diameter of 80 nm were used as condensation nuclei, and water vapor was generated by quantitative evaporation of a liquid jet. Droplet growth was monitored using the CAMS method. For determination of the accommodation coefficients, experimental droplet growth curves were compared to corresponding theoretical curves. Quantitative comparison was performed by varying the respective accommodation coefficient and the starting time of droplet growth in a two‐parameter best fit procedure. Considering the uncertainty with respect to the starting time of droplet growth and the uncertainties of the experimental water vapor supersaturation, corresponding maximum errors have been determined. From the results obtained it can be stated that αt is larger than 0.85 over the whole considered temperature range. For 250–270 K, values of αm below 0.8 are excluded, and for higher temperatures up to 290 K we can exclude values of αm below 0.4. Both coefficients are likely to be unity for all studied conditions. The results of this study enable accurate predictions of the formation and growth of cloud droplets required to parameterize cloud light scattering/absorption and precipitation properties in climate models.
Including quantum effects in the dynamics of complex (i.e., large) molecular systems
Authors: Miller William H.
Published: October 2006

The development in the 1950s and 1960s of crossed molecular beam methods for studying chemical reactions at the single-collision molecular level stimulated the need and desire for theoretical methods to describe these and other dynamical processes in molecular systems. Chemical dynamics theory has made great strides in the ensuing decades, so that methods are now available for treating the quantum dynamics of small molecular systems essentially completely. For the large molecular systems that are of so much interest nowadays (e.g., chemical reactions in solution, in clusters, in nanostructures, in biological systems, etc.), however, the only generally available theoretical approach is classical molecular dynamics (MD) simulations. Much effort is currently being devoted to the development of approaches for describing the quantum dynamics of these complex systems. This paper reviews some of these approaches, especially the use of semiclassical approximations for adding quantum effects to classical MD simulations, also showing some new versions that should make these semiclassical approaches even more practical and accurate.
Spin-wave damping at spin-orientation phase transitions
Authors: Baryakhtar V. G. , Danielevich A. G.
Published: October 2006

The spectra or spin waves and their damping in the vicinity of spin-orientation phase transitions are investigated. It is shown that if the ground state is degenerate and the degeneracy is characterized by a continuous degeneracy parameter, then the spin-wave damping is not described by a Landau-Lifshitz-Gilbert relaxation term. The dissipative function is constructed for ferromagnetic crystals of different symmetry. The cases of finite and zero longitudinal magnetic susceptibility are considered. A method of finding the relaxation term in the Landau-Lifshitz equation for crystals of different symmetry is given. The spin-wave spectra and damping are calculated for ferromagnets with uniaxial and tetragonal symmetry. It is shown that the relaxation process has a two-step character. In the first step an equilibrium value of the magnetization is established on account of the exchange interaction. In the second step the spin-wave amplitude is damped as the magnetization variable precesses around its equilibrium value. The details of the Bogolyubov method of quasi-averages in application to the case of ferromagnets with a spontaneously degenerate vacuum are discussed.
Enhanced edge Thomson scattering on MAST
Authors: Scannell R. , Walsh M. J. , Carolan P. G. , Conway N. J. , Darke A. C. , Dunstan M. R. , Hare D. , Prunty S. L.
Published: October 2006

A new edge Thomson scattering diagnostic has been implemented at MAST to complement an existing high spatial resolution ruby laser system and the high time sampling core Nd:YAG system. The Nd:YAG system comprises of four independently controllable lasers. Scattered light from these lasers is viewed at large scattering angle (153°) by a special optical arrangement in the new edge system. The Nd:YAG lasers are viewed at 16 contiguous spatial locations separated by ∼1cm each, located at the plasma outboard pedestal and scrape-off layer region. Here the use of a low f-number lens for the collection of a large solid angle of scattered light is particularly beneficial due to low plasma density (ne). The spectrum of scattered light is significantly broader at large scattering angles, allowing diagnosis of lower plasma temperatures (Te) while using the same spectrometer design as the core system. The four Nd:YAG lasers follow two separate slightly offset (<1∕3 of a spatial channel) optical paths through the vessel. This is useful when the lasers are used in burst mode for detailed edge studies of fast events such as ELMs. Polychromators have been designed to allow for both Raman and Rayleigh calibration. First results from this diagnostic are presented showing H-mode pedestal behavior. A novel spectral fitting technique has been devised and is applied to edge pedestal fitting.
Photodissociation of polycrystalline and amorphous water ice films at 157 and 193nm
Authors: Yabushita Akihiro , Kanda Daichi , Kawanaka Noboru , Kawasaki Masahiro , Ashfold Michael N. R.
Published: October 2006

The photodissociation dynamics of amorphous solid water (ASW) films and polycrystalline ice (PCI) films at a substrate temperature of 100K have been investigated by analyzing the time-of-flight (TOF) mass spectra of photofragment hydrogen atoms at 157 and 193nm. For PCI films, the TOF spectrum recorded at 157nm could be characterized by a combination of three different (fast, medium, and slow) Maxwell-Boltzmann energy distributions, while that measured at 193nm can be fitted in terms of solely a fast component. For ASW films, the TOF spectra measured at 157 and 193nm were both dominated by the slow component, indicating that the photofragment H atoms are accommodated to the substrate temperature by collisions. H atom formation at 193nm is attributed to the photodissociation of water species on the ice surface, while at 157nm it is ascribable to a mixture of surface and bulk photodissociations. Atmospheric implications in the high latitude mesopause region of the Earth are discussed.