bluuebunny/crossref_metadata_2025 huggingface dataset:
Planar waveguide‐resonator: a new device for x‐ray optics
Authors: Egorov V. K. , Egorov E. V.
Published: April 2004

Systematic investigations of the width dependence on the x‐ray beam propagation mechanism for a narrow extended slit formed by two plane dielectric plates are presented. It is shown that the mechanism of a multiple consecutive total reflection for Cu Kα radiation dominates in a slit width range s ≥ 3 µm. At the same time the manner of Cu Kα radiation propagation for super‐narrow slits s ≤ 0.1 µm is very different from the multiple total reflection mechanism. The x‐ray beam intensity proves to be constant for all this range of magnitude. This gives grounds to expect that the super‐narrow slit area is characterized by a specific type of mechanism of x‐ray beam propagation: waveguide‐resonance. A simple model for the waveguide‐resonance propagation mechanism based on the formation of a uniform x‐ray standing wave interference field in the total space of a narrow extended slit was developed. The design of a new x‐ray optical device, namely a planar x‐ray waveguide‐resonator, is proposed based on the waveguide‐resonance mechanism. Some properties of the composite planar x‐ray waveguide‐resonator are discussed. It is shown that under specific conditions the composite waveguide can demonstrate a partial tunneling effect of the x‐ray beam. The main applications of the new technique are discussed. Copyright © 2004 John Wiley & Sons, Ltd.
A new way of measuring the contribution of scattered photons to x‐ray fluorescence yields in secondary excitation mode
Authors: Kumar Ajay , Mehta D. , Singh Nirmal
Published: April 2004

The characteristic K x‐rays from a secondary exciter in conjunction with an x‐ray tube or a radioisotope as primary source are frequently used for target excitation in x‐ray fluorescence measurements. In this experimental arrangement, the exciting photon spectrum consists of two parts: (i) characteristic K x‐rays of the secondary exciter and (ii) photons from the primary source, which are scattered from the secondary exciter. A new method is proposed for correcting the observed target x‐ray yield due to unwanted excitation by the scattered photons. This method involves measurement of x‐ray yield after replacing the secondary exciter by an equivalent exciter consisting of a low‐Z element foil with a high‐Z element backing. Copyright © 2004 John Wiley & Sons, Ltd.
Semiconductor Peltier‐cooled detectors for x‐ray fluorescence analysis
Authors: Sokolov A. , Loupilov A. , Gostilo V.
Published: April 2004

We discuss recent results obtained in the development of Si(Li), Si p–i–n, CdTe p–i–n and CdZnTe x‐ray detectors with Peltier coolers for fabrication of laboratory and portable XRF analyzers. The characteristics of Si(Li) Peltier‐cooled detectors are close to those of detectors cooled with the liquid nitrogen and remain the most preferred type of detectors for the tasks of x‐ray fluorescence analysis. Considerable success was obtained in the improvement of the characteristics of CdTe p–i–n detectors and CdZnTe detectors with a metal–semiconductor–metal structure, effective in the energy range up to 100 keV. The spectra of all detectors are presented. Copyright © 2004 John Wiley & Sons, Ltd.
Measurements of the surface ionization in multilayered specimens
Authors: Merlet C. , Llovet X. , Salvat F.
Published: April 2004

Results from experimental measurements of surface ionization, Φ(0), from multilayered specimens are presented. The studied samples consisted of Cu and C layers of different thicknesses, deposited on single‐element substrates that cover the periodic system, from Be to Bi. The surface ionization was determined by the tracer method, i.e. by measuring the characteristic x‐ray intensity emitted from an ultra‐thin tracer layer deposited on the multilayer structure and, according to Castaing's definition, dividing it by the x‐ray intensity from an equivalent, self‐supporting tracer layer. The considered tracer element was Ni, and measurements were performed for Ni Kα and Ni Lα x‐rays. Experimental results are compared with Monte Carlo simulation results generated by using the general‐purpose simulation package PENELOPE with ionization cross‐sections computed from an optical‐data model. Measured data are also compared with the predictions of an empirical analytical expression for Φ(0), which was derived from systematic Monte Carlo simulations. Copyright © 2004 John Wiley & Sons, Ltd.
The Size of the Cross-Lingual Masked Phonological Priming Effect Does Not Depend on Second Language Proficiency
Authors: Duyck Wouter , Diependaele Kevin , Drieghe Denis , Brysbaert Marc
Published: April 2004

Abstract. Using a masked phonological priming paradigm, Brysbaert, Van Dyck, and Van de Poel (1999) showed that Dutch-French bilinguals perform better at identifying tachistoscopically presented L2 words (e.g., oui [yes]) when those words are primed by L1 words or nonwords that are homophonic to the L2 target word according to the L1 grapheme-phoneme conversion rules (e.g., wie [who]). They noted that this priming effect was smaller for balanced bilinguals than for less proficient bilinguals, although the interaction failed to reach significance. Findings of Gollan, Forster, and Frost (1997 ) suggest that this could be attributed to a greater reliance on phonology in L2 reading, caused by a smaller proficiency in this language. However, in this study we show that the Dutch-French cross-lingual phonological priming effect is equally large for perfectly balanced and less proficient bilinguals. Our findings are in line with more recent work of Van Wijnendaele and Brysbaert (2002 ).
Hierarchical Switching with Two Types of Judgment and Two Stimulus Dimensions
Authors: Kleinsorge Thomas
Published: April 2004

Abstract. A number of recent studies have shown that shifting among four tasks that result from a factorial combination of two types of judgment with two judgment-to-response mappings results in a characteristic pattern of shift costs that indicates a hierarchical representation of the two task features judgment and mapping (e.g., Kleinsorge & Heuer, 1999 ). In the present study, two types of judgment were combined with two stimulus dimensions. With this task combination, the same basic shift-cost pattern was observed. This suggests that a combination of two types of judgment with two stimulus dimensions also results in a hierarchically structured task representation, indicating that such a task representation is readily adopted by participants when the combination of task features is suitable for a hierarchical organization.
Cross-Notation Number Priming Investigated at Different Stimulus Onset Asynchronies in Parity and Naming Tasks
Authors: Reynvoet Bert , Brysbaert Marc
Published: April 2004

Abstract. In this paper, a parity judgment task and a number naming task were used to investigate cross-notational number priming. Primes and targets could be verbal (e.g., seven) or Arabic numbers (e.g., 7), and were always presented in a different notation within the same trial (either a verbal prime and an Arabic target or an Arabic prime and a verbal target). Previous experiments showed that response latencies increase when the distance between prime and target increases (for example, in a naming task, seven is pronounced faster after 6 than after 5). This semantic distance priming effect was the same for Arabic and verbal targets and was the same for within-notation trials as for cross-notation trials. In the present experiments, we wanted to investigate whether the cross-notational priming effect also occurs at SOAs shorter than the ones used in previous experiments. Therefore, we used SOAs of 43, 57, 86, and 115 ms. Semantic distance effects were indeed present at these shorter SOAs: Processing times in the semantic parity judgment task and in the non-semantic naming task increased when the distance between prime and target increased. The results are discussed and integrated within an interactive dual-route model of number processing that postulates that the impact of the semantic and the non-semantic route depends on the task and the notation of the stimuli.
Oculomotor Bias Induced by Number Perception
Authors: Fischer Martin H. , Warlop Nele , Hill Robin L. , Fias Wim
Published: April 2004

Abstract. Previous research with manual response methods has found evidence for an association between numbers and space. The present study investigated whether eye movements also show this association. Eye movement responses were recorded from 15 healthy participants as they categorized the digits 0-9 as odd or even. Responses were initiated faster to the left in response to small digits and faster to the right in response to large digits. Movement amplitudes were not systematically affected by either number magnitude or parity. These results provide further evidence for a spatially oriented “mental number line”.
Evaluation of ocean carbon cycle models with data‐based metrics
Authors: Matsumoto K. , Sarmiento J. L. , Key R. M. , Aumont O. , Bullister J. L. , Caldeira K. , Campin J.‐M. , Doney S. C. , Drange H. , Dutay J.‐C. , Follows M. , Gao Y. , Gnanadesikan A. , Gruber N. , Ishida A. , Joos F. , Lindsay K. , Maier‐Reimer E. , Marshall J. C. , Matear R. J. , Monfray P. , Mouchet A. , Najjar R. , Plattner G.‐K. , Schlitzer R. , Slater R. , Swathi P. S. , Totterdell I. J. , Weirig M.‐F. , Yamanaka Y. , Yool A. , Orr J. C.
Published: April 2004

New radiocarbon and chlorofluorocarbon‐11 data from the World Ocean Circulation Experiment are used to assess a suite of 19 ocean carbon cycle models. We use the distributions and inventories of these tracers as quantitative metrics of model skill and find that only about a quarter of the suite is consistent with the new data‐based metrics. This should serve as a warning bell to the larger community that not all is well with current generation of ocean carbon cycle models. At the same time, this highlights the danger in simply using the available models to represent the state‐of‐the‐art modeling without considering the credibility of each model.
Delaware River plume response to a strong upwelling‐favorable wind event
Authors: Houghton R. W. , Tilburg C. E. , Garvine R. W. , Fong A.
Published: April 2004

The mixing and secondary circulation in the Delaware River plume during a strong (10 m/s) upwelling‐favorable wind event in April 2003 have been observed using a dye tracer. The dye, injected into the halocline at the base of the plume, was surveyed for more than a day as it moved 28 km off shore. The secondary circulation within the plume was resolved as the dye patch dispersed. This flow pattern conformed with numerical model results of Fong and Geyer [2001] involving an upwelling flow 8.4 × 10−5 m/s (∼7.3 m/day) and a subsequent near surface, offshore flow (∼0.09 m/s) across the plume. The salting rate of the plume implied a mean vertical diffusivity of ∼2 × 10−4 m2/s where the gradient Richardson number was approximately 0.6.
Timing and progression of the Last Interglacial derived from a high alpine stalagmite
Authors: Holzkämper Steffen , Mangini Augusto , Spötl Christoph , Mudelsee Manfred
Published: April 2004

U/Th dating and oxygen isotope analysis of a stalagmite from Spannagel Cave in the Austrian Alps provides information about the timing and progression of the last interglacial climate. We determined two distinct growth intervals (warm climate) from ∼130.7 thousand years (ka) before the present to 130.0 ka and from ∼125.7 ka to 118.2 ka, the latter containing two periods of ceased stalagmite growth (colder climate) at around 123.8 ka and 120.5 ka. High resolution δ18O analysis of stalagmite SPA 50 reveals a clear regular cyclic pattern with periods of 197, 109, and 21 years, which are likely to be related to the Suess, Gleissberg, and Hale cycles respectively, indicating that Eemian climate in the Alps was forced by the Sun.
Relative timing of substorm onset phenomena
Authors: Kepko L. , Kivelson M. G. , McPherron R. L. , Spence H. E.
Published: April 2004

In this paper we examine the temporal ordering of midtail flow bursts, Pi2 pulsations, and auroral arc brightening at substorm onset. We present three substorm events for which the Geotail spacecraft was situated at local midnight, near the inner edge of the plasmasheet. We show that high‐speed, convective Earthward directed plasma flows observed by Geotail occurred 1–3 min before auroral onset as observed by the Polar Visible Imaging System and Ultraviolet Imager auroral imagers on board the Polar spacecraft. We also show that the onsets of both nightside Pi2 pulsations and magnetic bay variations were simultaneous with auroral onset. We argue that these observations lend strong support to the flow burst‐driven model of magnetotail dynamics. We also examine a high‐latitude magnetic precursor to onset and show that it is likely due to the currents expected from the passage of a flow burst through the plasmasheet prior to substorm onset. Finally, we calculate an analytic expression for this current and show that it is unlikely to generate discrete auroral structures.
Roles of saltation, sandblasting, and wind speed variability on mineral dust aerosol size distribution during the Puerto Rican Dust Experiment (PRIDE)
Authors: Grini Alf , Zender Charles S.
Published: April 2004

Recent field observations demonstrate that a significant discrepancy exists between models and measurements of large dust aerosol particles at remote sites. We assess the fraction of this bias explained by assumptions involving four different dust production processes. These include dust source size distribution (constant or dynamically changing according to saltation and sandblasting theory), wind speed distributions (using mean wind or a probability density function (PDF)), parent soil aggregate size distribution, and the discretization (number of bins) in the dust size distribution. The Dust Entrainment and Deposition global model is used to simulate the measurements from the Puerto Rican Dust Experiment (PRIDE) (2000). Using wind speed PDFs from observed National Centers for Environmental Prediction winds results in small changes in downwind size distribution for the production which neglects sandblasting, but it results in significant changes when production includes sandblasting. Saltation‐sandblasting generally produces more large dust particles than schemes which neglect sandblasting. Parent soil aggregate size distribution is an important factor when calculating size‐distributed dust emissions. Changing from a soil with large grains to a soil with smaller grains increases by 50% the fraction of large aerosols (D >5 μm) modeled at Puerto Rico. Assuming that the coarse medium sand typical of West Africa dominates all source regions produces the best agreement with PRIDE observations.
Large age differences between planktic foraminifers caused by abundance variations and Zoophycos bioturbation
Authors: Löwemark Ludvig , Grootes Pieter M.
Published: April 2004

The downward transport of surface sediment deep into the sediment column by the Zoophycos‐producing animal leads not only to large age differences between the Zoophycos structure and surrounding host sediment but also to large differences in age between different foraminifer species found inside the trace fossil. In the late Quaternary material from the southwestern Portuguese continental slope examined in this study, age differences of up to 2590 years were observed between the planktic foraminifer species Globigerinoides ruber and Globigerina bulloides. These differences are caused by the mixing of surface and host material with different abundances of the two species. If there are differences in the abundance of the two species at the surface and/or in the host sediment, plenty of relatively young foraminifers may be mixed with few relatively old ones, or vice versa. The age differences between species caused by the combination of deep‐reaching bioturbation by the Zoophycos producer and abundance variations may be considerably larger than the age differences caused by the homogenizing bioturbation in the mixed layer.
Continental rift architecture and patterns of magma migration: A dynamic analysis based on centrifuge models
Authors: Corti Giacomo , Bonini Marco , Sokoutis Dimitrios , Innocenti Fabrizio , Manetti Piero , Cloetingh Sierd , Mulugeta Genene
Published: April 2004

Small‐scale centrifuge models were used to investigate the role of continental rift structure in controlling patterns of magma migration and emplacement. Experiments considered the reactivation of weakness zones in the lower crust and the presence of magma at Moho depths. Results suggest that surface deformation, which reflects the weakness zone geometry, exerts a major control on patterns of magma migration. In the case of a single rift segment, the experimental lower crust and magma were both transferred in an extension‐parallel direction toward the rift flanks. This lateral migration reflected the dominance of far‐field stresses over extension‐induced buoyancy forces. Local pressure gradients favored the raise of experimental magma in correspondence of marginal grabens. The lateral migration gave rise to major accumulations below the footwall of major boundary faults, providing the magma source able to feed off‐axis volcanoes in nature, as inferred for the Main Ethiopian Rift. In the case of two offset rift segments, a major transfer zone developed. This transfer zone was characterized by prominent experimental lower crust doming and strong magma accumulation. Dynamic analysis showed that the transfer zone development caused a strong pressure difference in a rift‐parallel direction, which dominated over the far‐field thinning. Owing to this pressure gradient, almost all the underplated experimental magma collected below the lower crust dome, suggesting a rift‐parallel (extension‐orthogonal) migration. This process has a direct relevance for the localization of magmatic activity at transfer zones in natural continental rifts, such as in the Western Branch of the East African Rift System.
The three‐dimensional structure of the interleaving layers in the western equatorial Pacific Ocean
Authors: Lee Jae Hak , Richards Kelvin J.
Published: April 2004

The interleaving of water masses across the equator is a predominant feature in the upper equatorial Pacific Ocean. The interleaving is thought to promote lateral mixing and impact on the basin‐wide dynamics of the equatorial ocean. Hydrographic observations in the western equatorial Pacific have, for the first time, provided the three‐dimensional structure of the interleaving layers. Though the details are different, the general characteristics of the vertical and meridional structure are consistent with previous observations. The layers show a remarkably long zonal coherence, with individual layer being in excess of 700 km in length, which are matched only by intrusions in the Arctic. The large zonal coherence is further evidence of the potential importance of the interleaving, and points to the need to include the process in models of the equatorial ocean.
P2X7 receptors stimulate AKT phosphorylation in astrocytes
Authors: Jacques‐Silva Maria C , Rodnight Richard , Lenz Guido , Liao Zhongji , Kong Qiongman , Tran Minh , Kang Yuan , Gonzalez Fernando A , Weisman Gary A , Neary Joseph T
Published: April 2004

Emerging evidence indicates that nucleotide receptors are widely expressed in the nervous system. Here, we present evidence that P2Y and P2X receptors, particularly the P2X7 subtype, are coupled to the phosphoinositide 3‐kinase (PI3K)/Akt pathway in astrocytes.

P2Y and P2X receptor agonists ATP, uridine 5′‐triphosphate (UTP) and 2′,3′‐O‐(4‐benzoyl)‐benzoyl ATP (BzATP) stimulated Akt phosphorylation in primary cultures of rat cortical astrocytes. BzATP induced Akt phosphorylation in a concentration‐ and time‐dependent manner, similar to the effect of BzATP on Akt phosphorylation in 1321N1 astrocytoma cells stably transfected with the rat P2X7 receptor. Activation was maximal at 5 – 10 min and was sustained for 60 min; the EC50 for BzATP was approximately 50 μM. In rat cortical astrocytes, the positive effect of BzATP on Akt phosphorylation was independent of glutamate release.

The effect of BzATP on Akt phosphorylation in rat cortical astrocytes was significantly reduced by the P2X7 receptor antagonist Brilliant Blue G and the P2X receptor antagonist iso‐pyridoxal‐5′‐phosphate‐6‐azophenyl‐2′,4′‐disulfonic acid, but was unaffected by trinitrophenyl‐ATP, oxidized ATP, suramin and reactive blue 2.

Results with specific inhibitors of signal transduction pathways suggest that extracellular and intracellular calcium, PI3K and a Src family kinase are involved in the BzATP‐induced Akt phosphorylation pathway.

In conclusion, our data indicate that stimulation of astrocytic P2X7 receptors, as well as other P2 receptors, leads to Akt activation. Thus, signaling by nucleotide receptors in astrocytes may be important in several cellular downstream effects related to the Akt pathway, such as cell cycle and apoptosis regulation, protein synthesis, differentiation and glucose metabolism.

British Journal of Pharmacology (2004) 141, 1106–1117. doi:10.1038/sj.bjp.0705685
Cannabinoid CB1 receptor‐mediated modulation of evoked dopamine release and of adenylyl cyclase activity in the human neocortex
Authors: Steffens M , Engler C , Zentner J , Feuerstein T J
Published: April 2004

The present study investigated the binding characteristics of various ligands to cannabinoid CB1 receptors in human neocortex and amygdala. In addition, the functionality of CB1 receptors in the human neocortex was assessed by examining the effects of CB1 receptor ligands on evoked [3H]‐dopamine (DA) release in superfused brain slices and on synaptosomal cAMP accumulation.

Saturation‐binding assays in human neocortical and amygdala synaptosomes using a radiolabelled cannabinoid receptor agonist ([3H]‐CP55.940) revealed pKd values of 8.96 and 8.63, respectively. The numbers of binding sites (Bmax) were 3.99 and 2.67 pmol (mg protein)−1, respectively.

Various cannabinoid receptor ligands inhibited [3H]‐CP55.940 binding with rank order potencies corresponding to those of previous studies in animal tissues.

Electrically evoked [3H]‐DA release from human neocortical slices was inhibited by CP55.940 (IC50 6.76 nM, Imax 65%) and strongly enhanced by the cannabinoid receptor antagonist AM251. However, [3H]‐DA release was not influenced in rat neocortex. In human tissue, the estimated endocannabinoid concentration in the biophase of the release‐modulating CB1 receptors was 1.07 nM, expressed in CP55.940 units.

K+‐evoked [3H]‐DA release in the presence of tetrodotoxin (TTX) was strongly inhibited by CP55.940 in humans, but not in rats.

In human tissue, CP55.940 inhibited forskolin‐stimulated cAMP accumulation (IC50 20.89 nM, Imax 35%). AM251 blocked this effect and per se increased forskolin‐stimulated cAMP accumulation by ∼20%.

In conclusion, cannabinoids modulate [3H]‐DA release and adenylyl cyclase activity in the human neocortex. CB1 receptors are located on dopaminergic nerve terminals and seem to be tonically activated by endocannabinoids.

British Journal of Pharmacology (2004) 141, 1193–1203. doi:10.1038/sj.bjp.0705706
Identification in human airways smooth muscle cells of the prostanoid receptor and signalling pathway through which PGE2 inhibits the release of GM‐CSF
Authors: Clarke Deborah L , Belvisi Maria G , Catley Matthew C , Yacoub Magdi H , Newton Robert , Giembycz Mark A
Published: April 2004

The prostanoid receptor(s) on human airways smooth muscle (HASM) cells that mediates the inhibitory effect of PGE2 on interleukin (IL)‐1β‐induced granulocyte/macrophage colony‐stimulating factor (GM‐CSF) release has been classified.

IL‐1β evoked the release of GM‐CSF from HASM cells, which was suppressed by PGE2, 16,16‐dimethyl PGE2 (nonselective), misoprostol (EP2/EP3‐selective), ONO‐AE1‐259 and butaprost (both EP2‐selective) with pIC50 values of 8.61, 7.13, 5.64, 8.79 and 5.43, respectively. EP‐receptor agonists that have selectivity for the EP1‐ (17‐phenyl‐ω‐trinor PGE2) and EP3‐receptor (sulprostone) subtypes as well as cicaprost (IP‐selective), PGD2, PGF2α and U‐46619 (TP‐selective) were poorly active or inactive at concentrations up to 10 μM.

AH 6809, a drug that can be used to selectively block EP2‐receptors in HASM cells, antagonised the inhibitory effect of PGE2, 16,16‐dimethyl PGE2 and ONO‐AE1‐259 with apparent pA2 values of 5.85, 6.09 and 6.1 respectively. In contrast, the EP4‐receptor antagonists, AH 23848B and L‐161,982, failed to displace to the right the concentration–response curves that described the inhibition of GM‐CSF release evoked by PGE2 and ONO‐AE1‐259.

Inhibition of GM‐CSF release by PGE2 and 8‐Br‐cAMP was abolished in cells infected with an adenovirus vector encoding an inhibitor protein of cAMP‐dependent protein kinase (PKA) but not by H‐89, a purported small molecule inhibitor of PKA.

We conclude that prostanoid receptors of the EP2‐subtype mediate the inhibitory effect of PGE2 on GM‐CSF release from HASM cells by recruiting a PKA‐dependent pathway. In addition, the data illustrate that caution should be exercised when using H‐89 in studies designed to assess the role of PKA in biological processes.

British Journal of Pharmacology (2004) 141, 1141–1150. doi:10.1038/sj.bjp.0705716
Changes in the vascular β‐adrenoceptor‐activated signalling pathway in 2Kidney‐1Clip hypertensive rats
Authors: Callera Glaucia E , Yeh Ester , Tostes Rita C A , Caperuto Luciana C , Carvalho Carla R O , Bendhack Lusiane M
Published: April 2004

β‐Adrenoceptor (β‐AR)‐mediated vasodilation, which plays an important physiological role in the regulation of vascular tone, is decreased in two‐kidney, one clip (2K‐1C) renal hypertension. In this study, downstream pathways related to vascular β‐AR activation were evaluated in 2K‐1C rats.

Relaxation responses to isoprenaline, forskolin and 8‐Br‐cAMP were diminished in aortas without endothelium from 2K‐1C when compared to those in normotensive two kidney (2K). Basal adenosine‐3′,5′‐monophosphate (cAMP), as well as isoprenaline‐induced increase in cAMP levels, was not different between 2K and 2K‐1C aortas.

Contractile responses to caffeine, after depletion and reloading of intracellular Ca2+ stores, were greater in 2K‐1C than in 2K. The presence of isoprenaline during the Ca2+‐reloading period abolished the differences between groups by increasing caffeine contraction in 2K without changing this response in 2K‐1C aortas. Inhibition of the sarcolemmal Ca2+ATPase with thapsigargin markedly attenuated isoprenaline vasodilation in both 2K and 2K‐1C and abolished the differences between groups.

Blockade of ATP‐sensitive K+ channels (KATP) channels with glibenclamide significantly decreased isoprenaline vasodilation in 2K‐1C without affecting this response in 2K. Both vascular gene and protein expression of protein kinase A (PKA), as well as phosphoserine‐containing proteins, were increased in 2K‐1C vs 2K rats.

In conclusion, decreased isoprenaline vasodilation in 2K‐1C hypertensive rats is related to impaired modulation of the sarcolemmal Ca2+ATPase activity. Moreover, KATP channels may play a compensatory role on isoprenaline‐induced relaxation in renal hypertension. Both Ca2+ATPase and KATP channel functional alterations, associated with decreased β‐AR vasodilation, are paralleled by an upregulation of protein kinase A (PKA) and phosphoserine proteins expression.

British Journal of Pharmacology (2004) 141, 1151–1158. doi:10.1038/sj.bjp.0705717
Differential regulation of prostaglandin E biosynthesis by interferon‐γ in colonic epithelial cells
Authors: Wright Karen L , Weaver Sean A , Patel Kajal , Coopman Karen , Feeney Mark , Kolios George , Robertson Duncan A F , Ward Stephen G
Published: April 2004

Cyclooxygenase (COX)‐2 expression and activity in response to pro‐inflammatory cytokines TNFα and IFNγ was evaluated in the colonic epithelial cell line HT29 and the airway epithelial cell line A549.

TNFα induced concentration‐ and time‐dependent upregulation of COX‐2 mRNA, protein and prostaglandin (PG)E2 synthesis.

Co‐stimulation of TNFα with IFNγ resulted in reduced COX‐2 mRNA and protein expression.

IFNγ had no effect on the stability of TNFα‐induced COX‐2 mRNA.

TNFα‐induced PGE2 biosynthesis was significantly enhanced by the simultaneous addition of IFNγ and was COX‐2 dependent.

The combination of IFNγ and TNFα induced the microsomal prostaglandin E synthase (mPGES), comensurate with the enhanced PGE2 synthesis.

These results suggest that, in terms of PGE2 biosynthesis, IFNγ plays a negative regulatory role at the level of COX‐2 expression and a positive regulatory role at the level of mPGES expression. This may have important implications for the clinical use of IFNγ in inflammatory diseases.

British Journal of Pharmacology (2004) 141, 1091–1097. doi:10.1038/sj.bjp.0705719
Cerebral uptake of mefloquine enantiomers with and without the P‐gp inhibitor elacridar (GF1210918) in mice
Authors: De Lagerie Sylvie Barraud , Comets Emmanuelle , Gautrand Céline , Fernandez Christine , Auchere Daniel , Singlas Eric , Mentre France , Gimenez François
Published: April 2004

Mefloquine is a chiral neurotoxic antimalarial agent showing stereoselective brain uptake in humans and rats. It is a substrate and an inhibitor of the efflux protein P‐glycoprotein.

We investigated the stereoselective uptake and efflux of mefloquine in mice, and the consequences of the combination with an efflux protein inhibitor, elacridar (GF120918) on its brain transport.

Racemic mefloquine (25 mg kg−1) was administered intraperitoneally with or without elacridar (10 mg kg−1). Six to seven mice were killed at each of 11 time‐points between 30 min and 168 h after administration. Blood and brain concentrations of mefloquine enantiomers were determined using liquid chromatography.

A three‐compartment model with zero‐order absorption from the injection site was found to best represent the pharmacokinetics of both enantiomers in blood and brain. (−)Mefloquine had a lower blood and brain apparent volume of distribution and a lower efflux clearance from the brain, resulting in a larger brain/blood ratio compared to (+)mefloquine. Elacridar did not modify blood concentrations or the elimination rate from blood for either enantiomers. However, cerebral AUCinf of both enantiomers were increased, with a stronger effect on (+)mefloquine. The efflux clearance from the brain decreased for both enantiomers, with a larger decrease for (+)mefloquine.

After administration of racemic mefloquine in mice, blood and brain pharmacokinetics are stereoselective, (+)mefloquine being excreted from brain more rapidly than its antipode, showing that mefloquine is a substrate of efflux proteins and that mefloquine enantiomers undergo efflux in a stereoselective manner. Moreover, pretreatment with elacridar reduced the brain efflux clearances with a more pronounced effect on (+)mefloquine.

British Journal of Pharmacology (2004) 141, 1214–1222. doi:10.1038/sj.bjp.0705721
Multiple actions of anandamide on neonatal rat cultured sensory neurones
Authors: Evans Rhian M , Scott Roderick H , Ross Ruth A
Published: April 2004

We have investigated the effects of the endocannabinoid anandamide (AEA) on neuronal excitability and vanilloid TRPV1 receptors in neonatal rat cultured dorsal root ganglion neurones.

Using whole‐cell patch‐clamp electrophysiology, we found that AEA inhibits high‐voltage‐activated Ca2+ currents by 33±9% (five out of eight neurones) in the absence of the CB1 receptor antagonist SR141716A (100 nM) and by 32±6% (seven out of 10 neurones) in the presence of SR141716A.

Fura‐2 fluorescence Ca2+ imaging revealed that AEA produced distinct effects on Ca2+ transients produced by depolarisation evoked by 30 mM KCl. In a population of neurones of larger somal area (372±20 μm2), it significantly enhanced Ca2+ transients (80.26±13.12% at 1 μM), an effect that persists after pertussis toxin pretreatment. In a population of neurones of smaller somal area (279±18 μm2), AEA significantly inhibits Ca2+ transients (30.75±3.54% at 1 μM), an effect that is abolished by PTX pretreatment.

Extracellular application of 100 nM AEA failed to evoke TRPV1 receptor inward currents in seven out of eight neurones that responded to capsaicin (1 μM), with a mean inward current of −0.94±0.21 nA. In contrast, intracellular application of 100 nM AEA elicited robust inward currents in ∼62% of neurones, the mean population response was −0.85±0.21 nA. When AEA was applied to the intracellular environment with capsazepine (1 μM), the mean population inward current was −0.01±0.01 nA. Under control conditions, mean population current fluctuations of −0.09±0.05 nA were observed.

British Journal of Pharmacology (2004) 141, 1223–1233. doi:10.1038/sj.bjp.0705723
Involvement of bradykinin, cytokines, sympathetic amines and prostaglandins in formalin‐induced orofacial nociception in rats
Authors: Chichorro Juliana G , Lorenzetti Berenice B , Zampronio Aleksander R
Published: April 2004

This study characterises some of the mechanisms and mediators involved in the orofacial nociception triggered by injection of formalin into the upper lip of the rat, by assessing the influence of various treatments on behavioural nociceptive responses (duration of facial rubbing) elicited either by a low subthreshold (i.e. non‐nociceptive; 0.63%) or a higher concentration of the algogen (2.5%).

The kininase II inhibitor captopril (5 mg kg−1, s.c.) and prostaglandin(PG) E2 (100 ng lip−1) potentiated both phases of the response to 0.63% formalin, whereas tumour necrosis factor (TNFα; 5 pg lip−1), interleukin(IL)‐1β (0.5 pg lip−1), IL‐6 (2 ng lip−1) and IL‐8 (200 pg lip−1), or the indirectly acting sympathomimetic drug tyramine (200 μg lip−1), each augmented only the second phase of nociception.

Conversely, both phases of nociception induced by 2.5% formalin were inhibited by the bradykinin (BK) B2 receptor antagonist HOE140 (5 μg lip−1) or the selective β1‐adrenoceptor antagonist atenolol (100 μg lip−1). However, the BK B1 receptor antagonist des‐Arg9‐Leu8‐BK (1 and 2 μg lip−1), antibody and/or antiserum against each of the cytokines, the adrenergic neurone blocker guanethidine (30 mg kg−1 day−1, s.c., for 3 days) and the cyclooxygenase(COX)‐2 inhibitor celecoxib (50 and 200 μg lip−1, s.c.; or 1 and 3 mg kg−1, i.p.) reduced only the second phase of the response. The nonselective COX inhibitor indomethacin and the 5‐lipoxygenase activating protein inhibitor MK886 did not change formalin‐induced nociception.

Our results indicate that BK, TNF‐α, IL‐1β, IL‐6, IL‐8, sympathetic amines and PGs (but not leukotrienes) contribute significantly to formalin‐induced orofacial nociception in the rat and the response seems to be more susceptible to inhibition by B2 receptor antagonist and selective COX‐2 inhibitor than by B1 receptor antagonist or nonselective COX inhibitor.

British Journal of Pharmacology (2004) 141, 1175–1184. doi:10.1038/sj.bjp.0705724
Absence of PAF actions increases angiogenesis
Authors: Ziche Marina
Published: April 2004

British Journal of Pharmacology (2004) 141, 1085–1086. doi:10.1038/sj.bjp.0705728
Effects of cyclooxygenase inhibitor pretreatment on nitric oxide production, nNOS and iNOS expression in rat cerebellum
Authors: Girolamo G Di , Farina M , Riberio M L , Ogando D , Aisemberg J , Santos A R de los , Marti M L , Franchi A M
Published: April 2004

British Journal of Pharmacology (2004) 141, 1234. doi:10.1038/sj.bjp.0705771
Decreased expression of glial cell line‐derived neurotrophic factor signaling in rat models of neuropathic pain
Authors: Nagano Masatoshi , Sakai Atsushi , Takahashi Naoki , Umino Masahiro , Yoshioka Koichi , Suzuki Hidenori
Published: April 2004

British Journal of Pharmacology (2004) 141, 1235. doi:10.1038/sj.bjp.0705772
Asymmetric activation of Xer site‐specific recombination by FtsK
Authors: Massey Thomas H , Aussel Laurent , Barre François‐Xavier , Sherratt David J
Published: April 2004

Chromosome dimers, which frequently form in Escherichia coli, are resolved by the combined action of two tyrosine recombinases, XerC and XerD, acting at a specific site on the chromosome, dif, together with the cell division protein FtsK. The C‐terminal domain of FtsK (FtsKC) is a DNA translocase implicated in helping synapsis of the dif sites and in locally promoting XerD strand exchanges after synapse formation. Here we show that FtsKC ATPase activity is directly involved in the local activation of Xer recombination at dif, by using an intermolecular recombination assay that prevents significant DNA translocation, and we confirm that FtsK acts before Holliday junction formation. We show that activation only occurs with a DNA segment adjacent to the XerD‐binding site of dif. Only one such DNA extension is required. Taken together, our data suggest that FtsK needs to contact the XerD recombinase to switch its activity on using ATP hydrolysis.
Activation of Rho in the injured axons following spinal cord injury
Authors: Madura Tomas , Yamashita Toshihide , Kubo Tateki , Fujitani Masashi , Hosokawa Ko , Tohyama Masaya
Published: April 2004

Axons of the adult central nervous system have very limited ability to regenerate after injury. This inability may be, at least partly, attributable to myelin‐derived proteins, such as myelin‐associated glycoprotein, Nogo and oligodendrocyte myelin glycoprotein. Recent evidence suggests that these proteins inhibit neurite outgrowth by activation of Rho through the neurotrophin receptor p75NTR/Nogo receptor complex. Despite rapidly growing knowledge on these signals at the molecular level, it remained to be determined whether Rho is activated after injury to the central nervous system. To assess this question, we establish a new method to visualize endogenous Rho activity in situ. After treatment of cerebellar granular neurons with the Nogo peptide in vitro, Rho is spatially activated and colocalizes with p75NTR. Following spinal cord injury in vivo, massive activation of Rho is observed in the injured neurites. Spatial regulation of Rho activity may be necessary for axonal regulation by the inhibitory cues.
Effects of reciprocal chromosomal translocations on the fitness of Saccharomyces cerevisiae
Authors: Colson Isabelle , Delneri Daniela , Oliver Stephen G
Published: April 2004

Yeast species have undergone extensive genome reorganization in their evolutionary history, including variations in chromosome number and large chromosomal rearrangements, such as translocations. To determine directly the contribution of chromosomal translocations to the whole organism's fitness, we devised a strategy to construct in Saccharomyces cerevisiae collinear ‘evolutionary mimics’ of other species originally differing by the presence of reciprocal translocations in their genome. A modification of the Cre/loxP system was used to create in S. cerevisiae the translocations detected in the sibling species Saccharomyces mikatae IFO 1815 and 1816. Competition experiments under different physiological conditions showed that the translocated strains of S. cerevisiae consistently outcompeted the reference S. cerevisiae strain with no translocation, both in batch and chemostat culture, especially under glucose limitation. These results indicate that chromosomal translocations in Saccharomyces may have an adaptive significance, and lend support to a model of fixation by natural selection of reciprocal translocations in Saccharomyces species.
1.31 μ
m
InGaAs quantum dot light-emitting diodes grown directly in a GaAs matrix by metalorganic chemical-vapor deposition
Authors: Todaro M. T. , De Giorgi M. , Tasco V. , De Vittorio M. , Cingolani R. , Passaseo A.
Published: April 2004

We investigate the optical properties of light-emitting diodes (LEDs) operating at 1.3 μm embedding, in the intrinsic region, quantum dots (QDs) directly grown by metalorganic chemical-vapor deposition in a GaAs matrix, without indium in the barrier. The device characterization shows a full width at half maximum of the ground state emission as narrow as 24 meV at room temperature and a quenching of the emission between 30 K and room temperature as low as 2.75. Despite the low dot density (1.6×109 cm−2), the external quantum efficiency of our devices is 0.03%. This indicates that the individual QD efficiency of our devices is about 30% higher than that reported in the literature for state of the art InGaAs/InGaAs QD LEDs.
Three-terminal Si-based negative differential resistance circuit element with adjustable peak-to-valley current ratios using a monolithic vertical integration
Authors: Chung Sung-Yong , Jin Niu , Berger Paul R. , Yu Ronghua , Thompson Phillip E. , Lake Roger , Rommel Sean L. , Kurinec Santosh K.
Published: April 2004

Si-based resonant bipolar transistors are demonstrated by the monolithic vertical integration of Si-based resonant interband tunnel diodes atop the emitter of Si/SiGe heterojunction bipolar transistors (HBTs) on a silicon substrate. In the common emitter configuration, IC versus VCE shows negative differential resistance characteristics. The resulting characteristics are adjustable peak-to-valley current ratios, including infinite and negative values, and tailorable peak current densities by the control of the HBT base current under room temperature operation. With the integrated RITD-HBT combination, latching properties which are the key operating principle for high-speed mixed-signal, memory, and logic circuitry, are experimentally demonstrated.
High-speed operation of quasi-one junction superconducting quantum interference device based on high-Tc multilayer technology
Authors: Sugiyama H. , Wakana H. , Adachi S. , Tarutani Y. , Tanabe K.
Published: April 2004

We designed a quasi-one junction superconducting quantum interference device (QOS) based on single-flux-quantum technology using high-Tc superconductors. A circuit containing 10 interface-engineered ramp-edge Josephson junctions was fabricated on a La-substituted YBa2Cu3Oy ground plane. The output voltage as a function of the input current for the QOS indicated correct operation as a periodic comparator at clock frequency of 94 and 77 GHz at 35 and 40 K, respectively. A comparison of the observed maximum operating frequency with the product of the critical current and normal resistance for the junctions suggests that comparator operation above 100 GHz at 40 K is possible if one optimizes the junction parameters.
Organic electronics on paper
Authors: Eder Florian , Klauk Hagen , Halik Marcus , Zschieschang Ute , Schmid Günter , Dehm Christine
Published: April 2004

We have fabricated organic thin-film transistors and ring oscillators on paper and on flexible polyetherether ketone film using small-molecule hydrocarbon pentacene as the semiconductor and solution-processed polyvinylphenol as the gate dielectric. Transistors on paper have a carrier mobility of 0.2 cm2/V s and an on/off current ratio of 106, similar to devices on polyetherether ketone. A signal propagation delay of 22 μs per stage was measured for pentacene ring oscillators on polyetherether ketone film, and a signal delay of 12 ms was obtained for ring oscillators on paper.
Thermal stability of LaAlO3/Si deposited by laser molecular-beam epitaxy
Authors: Lu X. B. , Zhang X. , Huang R. , Lu H. B. , Chen Z. H. , Xiang W. F. , He M. , Cheng B. L. , Zhou H. W. , Wang X. P. , Wang C. Z. , Nguyen B. Y.
Published: April 2004

High-k gate dielectric material LaAlO3 (LAO) films were deposited directly onto silicon substrates by laser molecular-beam epitaxy. The thermodynamic stability of LAO films deposited at different substrate temperatures and of LAO films postannealed at 1000 °C was studied by high-resolution transmission electron microscopy and capacitor–voltage measurements. These studies show that the interfacial reaction between the LAO film and silicon substrate is strongly correlated to the substrate temperature and ambient conditions. In oxygen containing ambient, the interfacial reaction often occurs not only during film deposition but also during the course of postannealing. LAO films annealed at 1000 °C in nitrogen ambient have better thermal stability with silicon than LAO films annealed in oxygen ambient do. Both kinds of films remain amorphous after 1000 °C annealing.
Anticrossing between heavy-hole states in Si0.2Ge0.8/Si-coupled quantum wells grown on Si0.5Ge0.5 pseudosubstrate
Authors: Diehl L. , Borak A. , Mentese S. , Grützmacher D. , Sigg H. , Gennser U. , Sagnes I. , Campidelli Y. , Kermarrec O. , Bensahel D. , Faist J.
Published: April 2004

Intersubband absorption measurements were performed on a single repetition of coupled Si0.2Ge0.8/Si quantum wells grown on a Si0.5Ge0.5 pseudosubstrate. Two resonances observed at low temperature are identified with the optical transitions between the ground and the first excited heavy-hole states confined in the coupled wells through their anticrossing behavior. The measured coupling energy agrees well with calculated values. In addition, the Stark shift of a diagonal resonance between a heavy- and light-hole level was observed.
High-quality single-crystal Ge on insulator by liquid-phase epitaxy on Si substrates
Authors: Liu Yaocheng , Deal Michael D. , Plummer James D.
Published: April 2004

Ge on insulator (GOI) is desired to obtain metal-oxide-semiconductor transistors with high performance and low leakage current. We have developed a method to make GOI based on liquid-phase epitaxial (LPE) growth on Si substrates and a defect necking technique in which defects are confined to a very short distance. Self-aligned microcrucibles were used to hold the Ge liquid. High-quality single-crystal (100) as well as (111) oriented GOI structures were obtained with a process compatible with Si-based fabrication. No dislocations or stacking faults were found in the LPE Ge films on insulator. The orientation of the Ge crystals was controlled by the seeding Si substrate. This method opens up the possibility of integrating Ge device structures in a baseline Si integrated circuit process.
Elastic modulus and resonance behavior of boron nitride nanotubes
Authors: Suryavanshi Abhijit P. , Yu Min-Feng , Wen Jianguo , Tang Chengchun , Bando Yoshio
Published: April 2004

The effective elastic modulus (E) of boron nitride nanotubes (BNNTs) was measured using the electric-field-induced resonance method inside a transmission electron microscope. The average value of E from the measurements of 18 individually cantilevered BNNTs was 722 GPa, comparable to the theoretical estimate of ∼850 GPa. No strong variation of E with the diameter of the BNNTs, which spanned from 34 to 94 nm, was observed. Low quality factors (<680) obtained from the mechanical resonance is attributed to the layered structural nature of BNNT.
Polymer electrophosphorescence devices with high power conversion efficiencies
Authors: Yang X. H. , Neher D.
Published: April 2004

We demonstrate efficient single-layer polymer phosphorescent light-emitting devices based on a green-emitting iridium complex and a polymer host co-doped with electron-transporting and hole-transporting molecules. These devices can be operated at relatively low voltages, resulting in a power conversion efficiency of up to 24 lm/W at luminous efficiencies exceeding 30 cd/A. The overall performances of these devices suggest that efficient electrophosphorescent devices with acceptable operating voltages can be achieved in very simple device structures fabricated by spin coating.
Thermal-flow technique for reducing surface roughness and controlling gap size in polymer microring resonators
Authors: Chao Chung-Yen , Guo L. Jay
Published: April 2004

Q factors of microring resonator waveguide devices are primarily limited by the surface-roughness-induced scattering loss. Such surface roughness loss has been observed in waveguides that are fabricated from various types of materials, including semiconductors, dielectrics, and polymers. In this letter, we show that the surface roughness of polymer waveguides can be greatly reduced by a thermal-flow technique, and the effective reduction in waveguide loss was verified experimentally. In addition to smoothing surfaces, this technique can simultaneously shrink the gap distance in the coupling region of polymer microring resonators. This, in turn, provides higher coupling, lessens the difficulty of fabricating submicron gaps, and leads to more compact devices.