bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanism of action of benzodiazepines on GABAA receptors
Authors: Campo‐Soria Claudia , Chang Yongchang , Weiss David S
Published: June 2006

Wild‐type and mutant α1β2γ2 GABAA receptors were expressed in Xenopus laevis oocytes and examined using the two‐electrode voltage clamp.

Dose–response relationships for GABA were compared in the absence and presence of 1 μM diazepam (DZP) or methyl‐6,7‐dimethoxy‐4‐ethyl‐beta‐carboline‐3‐carboxylate (DMCM). The dose–current relationships yielded EC50's (concentration for half‐maximal activation) of 41.0±3.0, 21.7±2.7, and 118.3±6.8 μM for GABA, GABA plus DZP, and GABA plus DMCM, respectively.

DZP‐ and DMCM‐mediated modulation were examined in GABAA receptors in which the β‐subunit carries the L259S mutation. This mutation has been shown to produce spontaneous opening and impart a leftward shift in the dose–response relationship. In this case, neither DZP nor DMCM produced a significant alteration in the GABA dose–response relationship with GABA EC50's of 0.078±0.005, 0.12±0.03, and 0.14±0.004 μM for GABA, GABA plus 1 μM DZP, and GABA plus 1 μM DMCM.

DZP‐ and DMCM‐mediated modulations were examined in GABAA receptors in which the α‐subunit carries the L263S mutation. This mutation also produced spontaneous opening and a leftward shift of the GABA dose–response relation, but to a lesser extent than that of βL259S. In this case, the leftward and rightward shifts for DZP and DMCM were still present with EC50's=0.24±0.03, 0.14±0.02, and 1.2±0.04 μM for GABA, GABA plus 1 μM DZP, and GABA plus 1 μM DMCM, respectively.

Oocytes expressing ultrahigh levels of wild‐type GABAA receptors exhibited currents in response to 1 μM DZP alone, whereas DMCM decreased the baseline current. The DZP‐mediated activation currents were determined in wild‐type receptors as well as receptors in which the GABA binding site was mutated (β2Y205S). The EC50's for DZP‐mediated activation were 72.0±2.0 and 115±6.2 nM, respectively, similar to the EC50 for DZP‐mediated enhancement of the wild‐type GABA‐activated current (64.8±3.7 nM).

Our results support a mechanism in which DZP increases the apparent affinity of the receptor, not by altering the affinity of the closed state, but rather by shifting the equilibrium towards the high‐affinity open state.

British Journal of Pharmacology (2006) 148, 984–990. doi:10.1038/sj.bjp.0706796
The role of urotensin II in cardiovascular and renal physiology and diseases
Authors: Zhu Yi‐Chun , Zhu Yi‐Zhun , Moore Philip Keith
Published: June 2006

Urotensin II (U‐II) is a cyclic neuropeptide that was first isolated from teleost fish some 35 years ago. Mammalian U‐II is a powerful vasoconstrictor with a potency greater than that of endothelin‐1.

Nevertheless, unlike endothelin‐1, which constricts all or nearly all vascular beds, the vasoactive effects of U‐II are reported to be dependent both on the species and on the regional vascular bed examined. Typical regional variability occurs in the rat in which vasoconstriction to U‐II is most robust in thoracic aorta proximal to the aortic arch and decreases gradually towards the distal peripheral arteries. As small peripheral arteries but not larger arteries such as the aorta play a major role in regulating peripheral resistance and consequent blood pressure as well as workload on the heart, doubts have been raised concerning the importance of this peptide in cardiovascular physiology. Moreover, an interaction between U‐II and other endogenous vasoactive molecules may add a level of complexity to the vascular actions of U‐II.

On the other hand, recent experimental and clinical studies have revealed increased expression of U‐II and urotensin receptor (UT receptor) in animals with experimentally induced myocardial infarction, heart failure, and in patients with hypertension, atherosclerosis, and diabetic nephropathy, which suggests a potential role for U‐II in both cardiovascular and renal diseases. A series of peptidic and nonpeptidic UT receptor ligands have been shown to be effective in antagonizing the effects of U‐II in the cardiorenal system.

This article aims to review recent advances in our understanding of the physiology and pathophysiology of U‐II with particular references to its role in cardiovascular health and disease.

British Journal of Pharmacology (2006) 148, 884–901. doi:10.1038/sj.bjp.0706800
Stimulation of sensory neuropeptide release by nociceptin/orphanin FQ leads to hyperaemia in acutely inflamed rat knees
Authors: Zhang Chunfen , McDougall Jason J
Published: June 2006

The peripheral effect of the ‘opioid‐like’ peptide nociceptin/orphanin FQ (N/OFQ) on joint blood flow was investigated in acutely inflamed rats. Sensory neuropeptide release from capsaicin‐sensitive nerves and the involvement of synovial mast cells and leukocytes on these vasomotor responses were also studied.

Blood flow measurements of exposed knee joints were performed in urethane‐anaesthetised rats (2 mg kg−1intraperitoneal) using laser Doppler perfusion imaging. Topical administration of N/OFQ (10−13–10−8 mol) to acutely inflamed joints caused a dose‐dependent increase in synovial perfusion with an ED50of 4.0 × 10−10 mol. This vasodilatatory response was blocked by the selective NOP receptor antagonist [Phe1‐(CH2‐NH)‐Gly2]‐Nociceptin(1–13)‐NH2(10−9 mol) (P<0.0001).

Co‐administration of N/OFQ with the neurokinin‐1 (NK1) receptor antagonist [D‐Arg1,D‐Phe5,D‐Trp7,9,Leu11]‐Substance P (10−12 mol), the vasoactive intestinal peptide (VIP) receptor antagonist VIP6–28(10−9 mol) or the calcitonin gene‐related peptide (CGRP) receptor antagonist CGRP8–37(10−9 mol) all blocked the hyperaemic effect of N/OFQ (P<0.0001).

Treatment of acutely inflamed knees with capsaicin (8‐methyl‐N‐vanillyl‐6‐noneamide) to destroy unmyelinated joint afferents also inhibited N/OFQ vasomotor activity.

Stabilisation of synovial mast cells with disodium cromoglycate (cromolyn) ameliorated N/OFQ responses, whereas inactivation of circulating leukocytes with the pan‐selectin inhibitor fucoidin completely blocked N/OFQ‐induced hyperaemia in these joints.

These experiments show that in acutely inflamed knee joints, N/OFQ acts on NOP receptors located on synovial mast cells and leukocytes leading to the secondary release of proinflammatory mediators into the joint. These agents subsequently stimulate sensory neuropeptide release from capsaicin‐sensitive nerves culminating in vasodilatation and increased articular blood flow.

British Journal of Pharmacology(2006)148, 938–946. doi:10.1038/sj.bjp.0706804
Differential effects of Gram‐positiveversusGram‐negative bacteria on NOSII and TNFαin macrophages: role of TLRs in synergy between the two
Authors: Paul‐Clark Mark J , Mc Master Shaun K , Belcher Elizabeth , Sorrentino Rosalinda , Anandarajah Jasmine , Fleet Mark , Sriskandan Shiranee , Mitchell Jane A
Published: June 2006

Gram‐negative and Gram‐positive bacteria are sensed by Toll‐like receptor (TLR)4 and TLR2, respectively. TLR4 recruits MyD88 and TRIF, whereas TLR2 recruits MyD88 without TRIF. NOSII and TNFαare central genes in innate immunity and are thought to be differentially regulated by the MyD88versusTRIF signalling pathways. Here, we have used Gram‐positiveStaphylococcus aureus, Gram‐negativeEscherichia coliand highly selective TLR ligands to establish the precise relationship between TLR2, TLR1, TLR6 and TLR4 for NOSIIversusTNFαinduction.

In murine macrophages at 24 h,E. colior LPS (TLR4) induced NO and TNFαrelease. In contrast,S. aureus(TLR2/TLR1/TLR6) or Pam3CSK4 (TLR2/TLR1), or FSL‐1 and LTA (TLR2/TLR6) induced TNFαwithout an effect on NO.

At later time points (48–72 h),S. aureusinduced NO release. The ability ofS. aureus, but notE. colior LPS, to induce NO release was inhibited by anti‐TNFα‐binding antibodies.

At 24 h, LPS synergised with TLR2 ligands to induce NO release and NOSII protein expression. LPS also induced the expression of TLR2 gene expression without affecting levels of TLR4.

Using cells from TLR2−/−or TLR4−/−mice, the ability of LPS to synergise withS. aureusor Pam3CSK4 was found to be dependent on both TLR2 and TLR4.

These observations are the first to clearly delineate the role of separately activating TLR2 and TLR4 in the induction of NOSII and TNFαgenes compared with their coinduction when both receptor pathways are activated.

British Journal of Pharmacology(2006)148, 1067–1075. doi:10.1038/sj.bjp.0706815
Influence of Mn doping on the semiconducting properties of CaCu3Ti4O12 ceramics
Authors: Li Ming , Feteira Antonio , Sinclair Derek C. , West Anthony R.
Published: June 2006

Comparison of impedance spectroscopy data for undoped CaCu3Ti4O12 (CCTO) and CaCu2.94Mn0.06Ti4O12 CCMTO ceramics shows Mn doping to suppress the room temperature bulk semiconductivity of ∼0.01Scm−1 for CCTO by six orders of magnitude. The magnitude of and activation energy for bulk conduction in CCMTO are similar to those of the insulating grain boundaries in CCTO ceramics. A model to explain the suppression of the bulk conductivity in CCMTO ceramics is proposed; the grain and grain boundary regions in CCTO ceramics may consist of the same phase but with slightly different compositions.
Kinetics of the end of range damage dissolution in flash-assist rapid thermal processing
Authors: Camillo-Castillo R. A. , Law Mark E. , Jones Kevin S. , Radic Ljubo , Lindsay R. , McCoy S.
Published: June 2006

This study investigates the effectiveness of flash-assist rapid thermal processing in dissolving the end of range damage inherent to preamorphizing implants. A series of silicon wafers is preamorphized with a Ge implant and subsequently implanted with B. The wafers are then subjected to a flash anneal, a rapid thermal anneal, or both annealing processes. The flash anneal results in higher defect densities and trapped interstitials than the rapid thermal anneal. Defect dissolution has been previously reported to have an activation energy between 4 and 5eV. This work demonstrates that the defect dissolution during flash-assist rapid thermal processing is mediated by a 2.2±0.05eV activation energy.
On the radial distribution function of a hard-sphere fluid
Authors: López de Haro M. , Santos A. , Yuste S. B.
Published: June 2006

Two related approaches, one fairly recent [A. Trokhymchuk et al., J. Chem. Phys.123, 024501 (2005)] and the other one introduced 15years ago [S. B. Yuste and A. Santos, Phys. Rev. A43, 5418 (1991)], for the derivation of analytical forms of the radial distribution function of a fluid of hard spheres are compared. While they share similar starting philosophy, the first one involves the determination of 11 parameters while the second is a simple extension of the solution of the Percus-Yevick equation. It is found that the second approach has a better global accuracy and the further asset of counting already with a successful generalization to mixtures of hard spheres and other related systems.
Picosecond calorimetry: Time-resolved x-ray diffraction studies of liquid CH2Cl2
Authors: Georgiou Panayiotis , Vincent Jonathan , Andersson Magnus , Wöhri Annemarie B. , Gourdon Pontus , Poulsen Jens , Davidsson Jan , Neutze Richard
Published: June 2006

Liquid phase time-resolved x-ray diffraction with 100ps resolution has recently emerged as a powerful technique for probing the structural dynamics of transient photochemical species in solution. It is intrinsic to the method, however, that a structural signal is observed not only from the photochemical of interest but also from the embedding solvent matrix. To experimentally characterize the x-ray diffraction signal deriving from the solvent alone we performed time-resolved diffraction studies of a pure liquid sample over a time domain from −250psto2.5μs. Multiphoton excitation was used to rapidly heat liquid CH2Cl2 using UV pulses of 100fs duration. A significant x-ray diffraction signal is visible prior to the onset of thermal expansion, which characterizes a highly compressed superheated liquid. Liquid CH2Cl2 then expands as a shock wave propagates through the sample and the temporal dependence of this phenomenon is in good agreement with theory. An unexpectedly slow initial release of energy into the liquid as heat is observed from multiphoton excited CH2Cl2, revealing the presence of a metastable state of multiphoton excited CH2Cl2.
Pb-for-Bi substitution for enhancing thermoelectric characteristics of [(Bi,Pb)2Ba2O4±ω]0.5CoO2
Authors: Sakai K. , Karppinen M. , Chen J. M. , Liu R. S. , Sugihara S. , Yamauchi H.
Published: June 2006

We report strongly enhanced thermoelectric characteristics for a misfit-layered oxide, [Bi2Ba2O4±ω]0.5CoO2, in a wide temperature range, as achieved through substituting up to 20% of Bi by Pb. The Pb substitution kept the thermal conductivity (κ) unchanged but decreased the electrical resistivity (ρ) and increased the Seebeck coefficient (S) simultaneously, such that a three-fold enhancement in the thermoelectric figure of merit, Z (≡S2∕ρκ), was realized. At the same time x-ray absorption near-edge structure data indicated that the valence and spin states of Co are not affected by the Pb-for-Bi substitution.
Dielectrophoretic assembly of reversible and irreversible metal nanowire networks and vertically aligned arrays
Authors: Papadakis S. J. , Gu Z. , Gracias D. H.
Published: June 2006

We demonstrate the dielectrophoretic control of metallic nanowires (NWs) in liquid suspensions. By varying a range of parameters including the magnitude and frequency of the applied electric field, the liquid suspending the NWs, and the flow conditions, we demonstrate control over NW network formation and dissolution, as well as ordering of NWs into vertically aligned arrays. These results suggest a straightforward strategy for NW assembly and integration in devices.
Semitransparent organic photovoltaic cells
Authors: Bailey-Salzman Rhonda F. , Rand Barry P. , Forrest Stephen R.
Published: June 2006

We demonstrate semitransparent, small molecular weight organic solar cells employing a thin silver/indium tin oxide compound cathode with a maximum transmission of (60±6)% averaged over the visible spectral range and with a power conversion efficiency, ηp=(0.28±0.03)% under simulated, AM1.5G, 1 sun illumination. By increasing the Ag thickness, an average transmission of (26±3)% is achieved with ηp=(0.62±0.06)%, a value approximately half of that obtained for the same structure employing a conventional, reflective, and thick Ag cathode. A semitransparent tandem organic solar cell with ηp=(0.48±0.02)% and an average transmission of (44±4)% is also demonstrated. Semitransparent organic photovoltaic cells have potential uses as tinted and power-generating thin-film coatings on architectural surfaces, such as windows and walls. The use of a transparent top electrode also significantly simplifies the design of tandem cells, relaxing requirements for the placement of different absorbing materials at the maxima of optical fields introduced by reflective cathodes.
First principles study of CdSe quantum dots: Stability, surface unsaturations, and experimental validation
Authors: Yu M. , Fernando G. W. , Li R. , Papadimitrakopoulos F. , Shi N. , Ramprasad R.
Published: June 2006

Ab initio computational studies were performed for CdSe nanocrystals over a wide range of sizes and topologies. Substantial relaxations and coordination of surface atoms were found to play a crucial role in determining the nanocrystal stability and optical properties. While optimally (threefold) coordinated surface atoms resulted in stable closed-shell structures with large optical gaps, suboptimal coordination gave rise to lower stability and negligible optical gaps. These computations are in qualitative agreement with recent chemical etching experiments suggesting that closed-shell nanocrystals contribute strongly to photoluminescence quantum yield while clusters with nonoptimal surface coordination do not.
Zinc oxide nanocomb biosensor for glucose detection
Authors: Wang J. X. , Sun X. W. , Wei A. , Lei Y. , Cai X. P. , Li C. M. , Dong Z. L.
Published: June 2006

Single crystal zinc oxide nanocombs were synthesized in bulk quantity by vapor phase transport. A glucose biosensor was constructed using these nanocombs as supporting materials for glucose oxidase (GOx) loading. The zinc oxide nanocomb glucose biosensor showed a high sensitivity (15.33μA∕cm2mM) for glucose detection and high affinity of GOx to glucose (the apparent Michaelis-Menten constant KMapp=2.19mM). The detection limit measured was 0.02mM. These results demonstrate that zinc oxide nanostructures have potential applications in biosensors.
Ab initio computation of the mean inner Coulomb potential of wurtzite-type semiconductors and gold
Authors: Schowalter M. , Rosenauer A. , Lamoen D. , Kruse P. , Gerthsen D.
Published: June 2006

We report on the computation of mean inner Coulomb potentials of technologically important wurtzite-type semiconductors AlN, GaN, InN, ZnO, and CdO and of gold within the density functional theory formalism. We used a slab geometry with (11–20) and (110) surfaces, respectively. Structures consisting of several monolayers of material and an adjacent vacuum region were generated and the Coulomb potential was computed using the full potential linearized augmented plane wave method. The mean inner Coulomb potential was obtained by computing the difference of the potentials averaged inside the innermost monolayer of the slab and within the center plane of the vacuum region.
Achievement of alternative amorphous AlAs/crystalline AlGaAs multilayers
Authors: Wang Hao , Liao Changjun , Zheng Shuwen , Liu Songhao
Published: June 2006

A hybrid multilayer, composed of ten period amorphous AlAs/crystalline GaAlAs stacks, is realized by metalorganic chemical vapor deposition method on a GaAs substrate. Cross-sectional transmission electron microscopy shows the presence of sharp amorphous/crystalline interfaces. The electron diffraction patterns reveal the coexistence of both amorphous and crystalline phases and the perfect coherence of atom arrows between substrate and crystalline AlGaAs layers was also demonstrated. Perfect crystalline AlGaAs quality was further confirmed by x-ray rocking curves. The potential application of such hybrid multilayers is discussed and its behavior as a Bragg reflector is explored with a stop band gap of 75% reflectance.
Tension-compression strength asymmetry of nanocrystalline α-Fe2O3+fcc-Al ceramic-metal composites
Authors: Tomar Vikas , Zhou Min
Published: June 2006

The dependence on composition and loading direction of the strength of nanocrystalline α-Fe2O3+fcc-Al composites is analyzed using molecular dynamics simulations with a recently developed multicomponent interatomic potential. Compressive strength values are found to be higher than the tensile strength values at all volume fractions of the phases. Reverse Hall-Petch relations are observed for tension and forward Hall-Petch relations are observed for compression. The observed asymmetry in behavior and the direct or reverse nature of the Hall-Petch relations are found to reflect the different manners in which pairwise electrostatic forces influence grain boundary sliding which is the primary deformation mechanism.
Effect of reversed magnetic domains on superconductivity in Pb∕BaFe12O19 hybrids
Authors: Yang Zhaorong , de Vondel Joris Van , Gillijns Werner , Vinckx Wim , Moshchalkov Victor V. , Szymczak Ritta
Published: June 2006

In this letter, the effect of reversed magnetic domains of BaFe12O19 on superconductivity is investigated in Pb∕BaFe12O19 hybrids. The critical field of the Pb film is increased by about 5kOe due to the compensation of the applied field by the stray field above the reversed domains. Being related to smaller critical fields of Pb, at fields near the saturation field of BaFe12O19, the superconductivity can only exist above the reversed domains even at low temperatures. As a consequence of the pure reversed domain superconductivity, magnetic-field-induced superconductivity is observed in a broad temperature range.
Concentration evaluation method using broadband absorption spectroscopy for sulfur dioxide monitoring
Authors: Xu F. , Lv Z. , Zhang Y. G. , Somesfalean G. , Zhang Z. G.
Published: June 2006

We report on an approach for sulfur dioxide monitoring using broadband absorption spectroscopy in the ultraviolet spectral range. The method was applied in real-time measurements and has the advantage of straightforward data evaluation, limited susceptibility for interference from other gases, and low degree of complexity compared with other real-time optical detection techniques having the same precision. Concentration measurement is demonstrated at atmospheric pressure, which is of interest for pollution emission monitoring, yielding a detection limit of about 1ppm with 3s integration time. Comparison is made with low pressure measurements for validation of the accuracy of the method.
Performance limits of nanobiosensors
Authors: Nair P. R. , Alam M. A.
Published: June 2006

A simple analytical model, based on reaction-diffusion theory, is developed to predict the trade-off between average response (settling) time (ts) and minimum detectable concentration (ρ0) for nanobiosensors and nanochemical sensors. The model predicts a scaling relationship ρ0tsMD∼kD, where MD and kD are dimensionality dependent constants for one, two, and three dimensional nanosensors. We explore the performance limits of nanosensors using this analytical model and support its conclusions using detailed numerical simulation. Our results have obvious and significant implications for analyte density and response time reported in the literature and for design consideration of nanobiosensors and nanochemical sensors.
Transition metal atom heat processing for writing of crystal lines in glass
Authors: Honma Tsuyoshi , Benino Yasuhiko , Fujiwara Takumi , Komatsu Takayuki
Published: June 2006

A technique for the writing of crystal line in glass has been developed, in which a continuous-wave Nd:YAG laser (wavelength: λ=1064nm) is irradiated to the glasses containing transition metal (TM) ions such as Fe2+, Ni2+, and V4+. Laser energies are absorbed through d-d transitions of TM ions and dissipated to the lattice surrounding TM ions by nonradiative relaxation process, giving the increase in temperature in the laser irradiated region and inducing crystallization. This technique has been demonstrated for the writing of crystal lines consisting of nonlinear optical fresnoite-type Ba2TiGe2O8 and Ba2TiSi2O8 crystals in NiO-, Fe2O3-, and V2O5-doped (0.3–1mol%) BaO–TiO2–GeO2 and BaO–TiO2–SiO2 glasses. It is confirmed that crystals in the crystal lines are highly oriented along the laser scanning direction. The technique developed in this study is proposed to be called “transition metal atom heat processing.”
Electrohydrodynamic surface microvortices for mixing and particle trapping
Authors: Yeo Leslie Y. , Hou Diana , Maheshswari Siddharth , Chang Hsueh-Chia
Published: June 2006

We report a free-surface electrohydrodynamic flow phenomenon driven by an ionic wind mechanism induced by a high frequency gas-phase ac field (>10kHz). Intense vortices >1cm∕s are generated above a critical voltage, beyond which the vortices break down to spawn off new vortex pairs leading to a cascade of vortices over a continuum of length scales; the mixing efficiency approaches a turbulent-like state. Colloidal particles are attracted and aggregated into planar crystal structures within the vortices by a combination of dielectrophoresis and shear-induced diffusion.
Effects of curvature and compressibility on the stability of thermal fronts
Authors: Ibáñez S. Miguel H. , Bessega L. María C. , Shchekinov Yuri
Published: June 2006

The stability of subsonic thermal fronts against corrugation is analyzed and an exact dispersion relation is obtained taking into account the effects of the curvature of the distorted front as well as the compressibility of the gas. At a certain value of the Mach number ahead of the thermal front, unstable rates show a maximum; these rates drop to zero when a Chapman-Jouguet regime is established behind heat fronts. It is shown that curvature effects tend to stabilize conductive heat fronts propagating in a compressible gas.
Higher order approximations of the transmission and escape probability method for neutral particle transport in edge plasmas
Authors: Zhang Dingkang , Mandrekas J. , Stacey W. M.
Published: June 2006

Higher order approximations, which take into account the effects of angular anisotropy, spatial nonuniformity and energy dependence of the distribution of neutral particles, have been developed and implemented to extend the range of validity of the transmission and escape probabilities (TEP) method for the calculation of neutral particle transport in plasmas. Comparisons with Monte Carlo calculations of model test problems and DIII-D [J. Luxon, Nucl. Fusion, 42, 614 (2002)] L- and H-mode discharges show that these new extensions significantly improve the accuracy and extend the range of validity of the TEP methodology.
Dynamics of a growing cell in an optical trap
Authors: Volpe Giovanni , Singh Gajendra Pratap , Petrov Dmitri
Published: June 2006

We analyze the forward scattered light from a single optically trapped cell during its growth. We show that the cell continues adjusting itself to the applied optical force because of the growth processes, and hence it keeps changing its orientation in the trap. We point out the importance of taking this variation into account in the interpretation of spectroscopic data. This method can also be used as a means for cell identification and cell sorting.
Control of saturation magnetization, anisotropy, and damping due to Ni implantation in thin Ni81Fe19 layers
Authors: Fassbender J. , McCord J.
Published: June 2006

The layer magnetization, the saturation magnetization as well as the magnetic anisotropy, and damping behavior of 20nm thick Ni81Fe19 films have been modified by 30keV Ni ion implantation with fluences up to 1×1016Ni∕cm2 (≈5at.%). With increasing ion fluence a magnetic dead layer of increasing thickness is formed which leads to a reduction of the total magnetization. In addition, the saturation magnetization of the residual ferromagnetic film decreases due to, both, a shift in stoichiometry and radiation damage. Accordingly a reduction of the magnetic anisotropy and a strong enhancement of the magnetic damping parameter are observed. Moreover, ion implantation in an applied magnetic field allows the setting of the uniaxial anisotropy direction irrespective of its original orientation. Static and dynamic magnetic properties of Ni81Fe19 films can be tailored over a wide range after film deposition.
Hysteresis mechanism and reduction method in the bottom-contact pentacene thin-film transistors with cross-linked poly(vinyl alcohol) gate insulator
Authors: Lee Cheon An , Park Dong Wook , Jin Sung Hun , Park Il Han , Lee Jong Duk , Park Byung-Gook
Published: June 2006

The origin of the hysteresis phenomenon in bottom-contact pentacene organic thin-film transistors (OTFTs) with cross-linked poly(vinyl alcohol) (PVA) insulator is studied. From electrical measurements with various sweep ranges and two different sweep directions, the hysteresis effect is presumed to be caused by the electrons or holes that could be injected from the gate and trapped in the PVA bulk, rather than by the polarization or internally existing mobile ions. The assumption is confirmed by the clear reduction of hysteresis in OTFTs with a blocking oxide layer between gate and PVA insulator.
Luminescent properties of solution-grown ZnO nanorods
Authors: Hsu J. W. P. , Tallant D. R. , Simpson R. L. , Missert N. A. , Copeland R. G.
Published: June 2006

The optical properties of solution-grown ZnO nanorods were investigated using photoluminescence and cathodoluminescence. The as-grown nanorods displayed a broad yellow-orange sub-band-gap luminescence and a small near-band-gap emission peak. The sub-band-gap luminescence can only be observed when exciting above band gap. Scanning cathodoluminescence experiments showed that the width of the sub-band-gap luminescence is not due to an ensemble effect. Upon reduction, the sub-band-gap luminescence disappeared and the near-band-gap emission increased. Compared to ZnO powders that are stoichiometric and oxygen deficient, we conclude that the yellow-orange sub-band-gap luminescence most likely arises from bulk defects that are associated with excess oxygen.
The Sleep Deprivation Attack in Sensor Networks: Analysis and Methods of Defense
Authors: Pirretti Matthew , Zhu Sencun , Vijaykrishnan N. , McDaniel Patrick , Kandemir Mahmut , Brooks Richard
Published: June 2006

The ability of sensor nodes to enter a low power sleep mode is very useful for extending network longevity. We show how adversary nodes can exploit clustering algorithms to ensure their selection as cluster heads for the purpose of launching attacks that prevent victim nodes from sleeping. We present two such attacks: the barrage attack and the sleep deprivation attack. The barrage attack bombards victim nodes with legitimate requests, whereas the sleep deprivation attack makes requests of victim nodes only as often as in necessary to keep the victims awake. We show that while the barrage attack causes its victims to spend slightly more energy, it is more easily detected and requires more effort on behalf of the attacker. Thus, we have focused our research on the sleep deprivation attack. Our analysis indicates that this attack can nullify any energy savings obtained by allowing sensor nodes to enter sleep mode. We also analyze three separate methods for mitigating this attack: the random vote scheme, the round robin scheme, and the hash-based scheme. We have evaluated these schemes based upon their ability to reduce the adversary's attack, the amount of time required to select a cluster head, and the amount of energy required to perform each scheme. We have found that of the three clustering methods analyzed, the hash-based scheme is the best at mitigating the sleep deprivation attack.
Vulnerability of Surveillance Networks to Faults
Authors: Chin Tai-Lin , Clouqueur Thomas , Ramanathan Parameswaran , Saluja Kewal K.
Published: June 2006

Recent advances in technology have made it possible to build surveillance systems using many low-cost sensor nodes with limited computation and communication capabilities. Due to a potentially large number of nodes deployed, node failures are inevitable and can render a surveillance system that has degraded detection performances. The exposure metric has been proposed earlier to assess the quality of a surveillance system based on the detection performances. In this paper, we characterize the vulnerability of a system in terms of its exposure with respect to the number of faulty nodes and their combinations. Specifically, we assess the exposure of a surveillance network subject to a given number of faulty nodes, and identify the worst-case fault combination for both an idling target and a traversing target. For an idling target, the worst-case fault combination and exposure is analytically identified. For a traversing target, a genetic algorithm based approach is proposed to derive a near worst-case fault combination, and extensive simulation results are presented to show the effectiveness of the algorithm.
The V0-ATPase mediates apical secretion of exosomes containing Hedgehog-related proteins in Caenorhabditis elegans
Authors: Liégeois Samuel , Benedetto Alexandre , Garnier Jean-Marie , Schwab Yannick , Labouesse Michel
Published: June 2006

Polarized intracellular trafficking in epithelia is critical in development, immunity, and physiology to deliver morphogens, defensins, or ion pumps to the appropriate membrane domain. The mechanisms that control apical trafficking remain poorly defined. Using Caenorhabditis elegans, we characterize a novel apical secretion pathway involving multivesicularbodies and the release of exosomes at the apical plasma membrane. By means of two different genetic approaches, we show that the membrane-bound V0 sector of the vacuolar H+-ATPase (V-ATPase) acts in this pathway, independent of its contribution to the V-ATPase proton pump activity. Specifically, we identified mutations in the V0 “a” subunit VHA-5 that affect either the V0-specific function or the V0+V1 function of the V-ATPase. These mutations allowed us to establish that the V0 sector mediates secretion of Hedgehog-related proteins. Our data raise the possibility that the V0 sector mediates exosome and morphogen release in mammals.
Identification of novel chondroitin proteoglycans in Caenorhabditis elegans: embryonic cell division depends on CPG-1 and CPG-2
Authors: Olson Sara K. , Bishop Joseph R. , Yates John R. , Oegema Karen , Esko Jeffrey D.
Published: June 2006

Vertebrates produce multiple chondroitin sulfate proteoglycans that play important roles in development and tissue mechanics. In the nematode Caenorhabditis elegans, the chondroitin chains lack sulfate but nevertheless play essential roles in embryonic development and vulval morphogenesis. However, assignment of these functions to specific proteoglycans has been limited by the lack of identified core proteins. We used a combination of biochemical purification, Western blotting, and mass spectrometry to identify nine C. elegans chondroitin proteoglycan core proteins, none of which have homologues in vertebrates or other invertebrates such as Drosophila melanogaster or Hydra vulgaris. CPG-1/CEJ-1 and CPG-2 are expressed during embryonic development and bind chitin, suggesting a structural role in the egg. RNA interference (RNAi) depletion of individual CPGs had no effect on embryonic viability, but simultaneous depletion of CPG-1/CEJ-1 and CPG-2 resulted in multinucleated single-cell embryos. This embryonic lethality phenocopies RNAi depletion of the SQV-5 chondroitin synthase, suggesting that chondroitin chains on these two proteoglycans are required for cytokinesis.
Cubic membranes: a legend beyond the Flatland* of cell membrane organization
Authors: Almsherqi Zakaria A. , Kohlwein Sepp D. , Deng Yuru
Published: June 2006

Cubic membranes represent highly curved, three-dimensional nanoperiodic structures that correspond to mathematically well defined triply periodic minimal surfaces. Although they have been observed in numerous cell types and under different conditions, particularly in stressed, diseased, or virally infected cells, knowledge about the formation and function of nonlamellar, cubic structures in biological systems is scarce, and research so far is restricted to the descriptive level. We show that the “organized smooth endoplasmic reticulum” (OSER; Snapp, E.L., R.S. Hegde, M. Francolini, F. Lombardo, S. Colombo, E. Pedrazzini, N. Borgese, and J. Lippincott-Schwartz. 2003. J. Cell Biol. 163:257–269), which is formed in response to elevated levels of specific membrane-resident proteins, is actually the two-dimensional representation of two subtypes of cubic membrane morphology. Controlled OSER induction may thus provide, for the first time, a valuable tool to study cubic membrane formation and function at the molecular level.
Apical targeting of syntaxin 3 is essential for epithelial cell polarity
Authors: Sharma Nikunj , Low Seng Hui , Misra Saurav , Pallavi Bhattaram , Weimbs Thomas
Published: June 2006

In polarized epithelial cells, syntaxin 3 localizes to the apical plasma membrane and is involved in membrane fusion of apical trafficking pathways. We show that syntaxin 3 contains a necessary and sufficient apical targeting signal centered around a conserved FMDE motif. Mutation of any of three critical residues within this motif leads to loss of specific apical targeting. Modeling based on the known structure of syntaxin 1 revealed that these residues are exposed on the surface of a three-helix bundle. Syntaxin 3 targeting does not require binding to Munc18b. Instead, syntaxin 3 recruits Munc18b to the plasma membrane. Expression of mislocalized mutant syntaxin 3 in Madin-Darby canine kidney cells leads to basolateral mistargeting of apical membrane proteins, disturbance of tight junction formation, and loss of ability to form an organized polarized epithelium. These results indicate that SNARE proteins contribute to the overall specificity of membrane trafficking in vivo, and that the polarity of syntaxin 3 is essential for epithelial cell polarization.
Invertebrate bioturbation can reduce the clogging of sediment: an experimental study using infiltration sediment columns
Authors: NOGARO GERALDINE , MERMILLOD‐BLONDIN FLORIAN , FRANÇOIS‐ CARCAILLET FREDERIQUE , GAUDET JEAN‐PAUL , LAFONT MICHEL , GIBERT JANINE
Published: June 2006

1. Invertebrate bioturbation can strongly affect water‐sediment exchanges in aquatic ecosystems. The objective of this study was to quantify the influence of invertebrates on the physical characteristics of an infiltration system clogged with fine sediment.

2. Two taxa (chironomids and tubificids) with different bioturbation activities were studied in experimental slow infiltration columns filled with sand and gravel and clogged with a 2 cm layer of fine sediment at the surface. We measured the effects of each taxon separately and combined on hydraulic head, water mobility and sediment reworking.

3. The results showed that invertebrates could reduce sediment clogging and this effect was linked to the functional mode of bioturbation of each group. Tubificid worms dug networks of galleries in the fine sediment, creating pathways for water flow, which reduced the clogging of sediment. In contrast, the U‐shaped tubes of chironomids were restricted to the superficial layer of fine sediments and did not modify the hydraulic conductivity of experimental columns. The combination of invertebrates did not show any interactive effects between tubificids and chironomids. The occurrence of 80 tubificids in the combination was enough to maintain the same hydraulic conductivity that 160 worms did in monospecific treatment.

4. The invertebrates like tubificid worms can have a great benefit on functioning of clogged interfaces by maintaining high hydraulic conductivity, which contributes to increased water‐sediment exchanges and stimulates biogeochemical and microbial processes occurring in river sediments.
Impact of eating disorders on family life: individual parents’ stories
Authors: Hillege Sharon , Beale Barbara , McMaster Rose
Published: June 2006

Aims and objectives.  The aim of this study was to consider the impact that an eating disorder had on the family, particularly the parents. The objective was to give a voice to parents in order to develop new understandings of their experience leading to more appropriate clinical decision‐making.

Background.  The impact of an eating disorder on family life has not been well‐documented in the published literature. There are numerous articles from the sufferer's perspective and treatment modalities. The following paper describes a component of a larger study that explored the parent's perspective of having a child with an eating disorder.

Design.  Nineteen mothers and three fathers from Sydney, Australia, volunteered to be interviewed as the result of advertizements placed in parent support organization newsletters and by using the snowballing technique.

Methods.  A qualitative approach using semi‐structured interviews was used to explore parents’ experiences of having a child/adult child with an eating disorder. Themes were identified through in depth analysis.

Results.  Themes that were extrapolated from this research included, family unification or disintegration, parent's inability to cope, inconsiderate comments from significant others, social isolation and financial impacts.

Conclusions.  This study reports five overarching effects on family life. The authors conclude that one way in which the life of parents and families could be improved would be increased involvement and integration into the treatment process. For this to happen, health professionals would need to acknowledge the family as a resource.

Relevance to clinical practice.  This research documents the family struggle and highlights the current omissions concerning the family's role. The need for changes to clinical practice is substantiated. It requires health professionals to scrutinize their own clinical practice and consider modification of the treatment process.
Influence of topical capsaicin on facial sensitivity in response to experimental pain
Authors: LEE Y.‐S. , KHO H.‐S. , KIM Y.‐K. , CHUNG S.‐C.
Published: June 2006

summary Capsaicin, the pungent component of the red pepper, has been used as an analgesic in a variety of pain conditions, but sensory impairment after long‐term treatment has been concerned. This study investigated the influence of topical capsaicin on various types of sensations including pain in the facial areas innervated by the mental nerve, and also evaluated whether the measurement of cutaneous current perception threshold (CPT) is reliable for the quantification of sensory change following capsaicin application. Twenty healthy subjects were given topical capsaicin cream (0·075%), which was applied to the mental area unilaterally, four times daily for 2 weeks. Burning sensation after capsaicin application gradually decreased with repeated applications. Repeated topical capsaicin resulted in reduced sensation to mechanical, heat and cold pain without changing non‐painful tactile sensation. It also resulted in increased CPTs at 5 Hz and 250 Hz stimuli but no change in the CPTs at 2000 Hz from the first evaluation after capsaicin treatment and throughout the treatment period. This study demonstrated that topical capsaicin treatment for the management of chronic localized pain can be safely applied to the face without affecting non‐painful normal sensations, and that CPT testing is a clinically useful tool for the quantification of sensory changes following capsaicin application.
Effects of iron excess on cell viability and mitogen‐activated protein kinase activation in rice roots
Authors: Tsai Tsung‐Mu , Huang Hao‐Jen
Published: June 2006

Iron is an essential micronutrient for normal growth and development of plants. However, at high concentrations, iron can become toxic to plants. Very little information is known about the molecular mechanism responsible for the regulation of plant growth by excess iron. The aim of this study was to investigate the signal transduction pathway activated by increasing concentrations (0.5, 1.0, and 2.5 mm) of iron. We showed that iron elicited a remarkable myelin basic protein (MBP) kinase activity. By Western blot and immunoprecipitation analysis, we suggested that iron‐activated 42‐kDa MBP kinase is a mitogen‐activated protein kinase (MAPK). Cell death in rice roots due to iron toxicity was investigated using inhibitors of signal molecules known to regulate programmed cell death in plants. Phenylarsine oxide (PAO) and sodium orthovanadate, known inhibitors of tyrosine phosphatase, reduced iron‐induced root cell death, but cantharidin and endothall two‐serine/threonine phosphatase inhibitor enhanced iron‐induced root cell death. Moreover, our results revealed that H+‐ATPase might participate in iron‐induced cell death. These results suggested that the MAPK, reactive oxygen species, protein phosphatase, and H+‐ATPase might function in the plant iron‐triggered signaling pathway in rice roots.
On the logical relationship between natural selection and self-organization
Authors: Hoelzer G. A. , Smith E. , Pepper J. W.
Published: June 2006

Most evolutionary biologists cherish Darwin's theory of natural selection (NS) as the process of adaptive evolution more than 140 years after publication of his first book on the subject. However, in the past few decades the study of self-organization (SO) in complex dynamical systems has suggested that adaptation may occur through intrinsic reorganization without NS. In this study, we attempt to describe the logical framework that relates the general process of SO to the specific process of NS. We describe NS as a mechanism that coordinates the coevolution of species in an ecosystem to effectively capture, process and dissipate solar energy into the earth's shadow. Finally, we conclude that NS is an emergent process founded on the same thermodynamic imperatives that are thought to underlie all SO. This perspective suggests that the theory of self-organizing systems offers a broader physical context in which to understand the process of NS, rather than contesting it. It even suggests the possibility that there may be a physical basis for understanding the origin of the process of NS. Rather than being merely a fluke of nature, the origin of NS that may be driven by energy flows across gradients.
Cleavage fracture of RPV steel following warm pre‐stressing: micromechanical analysis and interpretation through a new model
Authors: BORDET S. R. , TANGUY B. , BESSON J. , BUGAT S. , MOINEREAU D. , PINEAU A.
Published: June 2006

In this paper, the warm pre‐stress (WPS) effect on the cleavage fracture of an 18MND5 (A533B) RPV steel is investigated. This effect, which describes the effective enhancement of the cleavage fracture toughness at low temperature following a prior loading at high temperature, has received great interest in light of its significance in the integrity assessment of structures, such as nuclear pressure vessels, subjected to thermal transients. Several loading cycles between room temperature (RT) and −150 °C are considered: Load‐Unload‐Cool‐Fracture (LUCF), Load‐Cool‐Fracture (LCF) and Load‐Cool with Increasing K‐Fracture (LCIKF). All experiments complied with the conservative principle, which states that no fracture will occur if the applied stress intensity factor (SIF) decreases (or is held constant) while the temperature at the crack‐tip decreases, even if the fracture toughness of the virgin material is exceeded. The experimental results indicate that an effective WPS effect is present even at small pre‐load (Kwps= 40 MPa√m), and that a minimum critical slope (−ΔK/ΔT) in the LCIKF cycle has to be exceeded to induce cleavage fracture between RT and −150 °C. Numerical modelling was performed using mixed isotropic and kinematic hardening laws identified on notched tensile (NT) specimens, tested in tension to large strains (up to 40%), followed by large compressive strains. Detailed microstructural investigations on compact tensile (CT) and NT fracture test specimens were performed so as to determine the nature of the cleavage initiation sites, as well as the local mechanical conditions at fracture. Based on this local information, a new cleavage model was calibrated and applied to predict the probability of cleavage fracture after WPS: it is shown that the predictions are in good agreement with the experimental results.