bluuebunny/crossref_metadata_2025 huggingface dataset:
Space shuttle observation of an unusual transient atmospheric emission
Authors: Yair Yoav , Price Colin , Ziv Baruch , Israelevich Peter L. , Sentman Davis D. , São‐Sabbas Fernanda T. , Devir Adam D. , Sato Mitsuteru , Rodger Craig J. , Moalem Meir , Greenberg Eran , Yaron Ofer
Published: January 2005

We report an observation of an unusual transient luminous event (TLE) detected in the near IR, south of Madagascar above the Indian Ocean. The event was imaged from the space shuttle Columbia during the MEIDEX sprite campaign [Yair et al., 2004]. It was delayed 0.23 seconds from a preceding visual lightning flash which was horizontally displaced >1000 km from the event. The calculated brightness in the 860 (±50) nm filter was ∼310 ± 30 kR, and the morphology of the emitting volume did not resemble any known class of TLE (i.e., sprites, ELVES or halos). This TIGER event (Transient Ionospheric Glow Emission in Red) may constitute a new class of TLE, not necessarily induced by a near‐by thunderstorm. We discuss possible generation mechanisms, including the conjugate sprite hypothesis caused by lightning at the magnetic mirror point, lightning‐induced electron precipitation and an extraterrestrial source, meteoric or cometary.
Nonstationary ENSO‐precipitation teleconnection over the equatorial Indian Ocean documented in a coral from the Chagos Archipelago
Authors: Timm Oliver , Pfeiffer Miriam , Dullo Wolf‐Christian
Published: January 2005

This study proposes a mechanism that explains the marked shift in the correlation between the El Niño/Southern Oscillation (ENSO) and the isotopic composition (δ18Oc) of a Porites coral from the Chagos Archipelago (71°E/5°S). Only after the mid‐1970s a strong ENSO signal emerges in the δ18Oc during the analyzed period 1950–1994. In the 1970s, the increasing sea surface temperature (SST) shifted the mean SST closer to the deep convection threshold at about 28.5°C. ENSO‐related SST variability largely controls the deep convection and precipitation in the central equatorial Indian Ocean (CEIO) when the SST is at this critical level. The anomalies in the precipitation induce changes in the isotopic composition of the surface ocean waters. The precipitation signal amplifies the SST signal in the coral δ18Oc and raises the correlation to ENSO. The presented results have important implications for the reconstruction of ENSO indices from corals within the Indian Ocean.
Comparison of topside equatorial parameters derived from DMSP, Jicamarca, and Another Model of the Ionosphere (SAMI2)
Authors: Venkatraman Sarita , Heelis R. A. , Hysell D. L.
Published: January 2005

Comparison is made of topside equatorial parameters obtained from DMSP satellites with those measured from Jicamarca radar and those calculated from Another Model of the Ionosphere (SAMI2). To determine acceptable limits for this volume, knowledge of the spatial and temporal gradients in the parameters must be defined. Those can be obtained independently from each data source and are dependent on local time and season. Having described the spatial gradients, a comparison of the ionospheric variables can be made. The present study focuses on simultaneous ground‐based and satellite data obtained for June 2002. Data for days 11, 12, and 13 are compared in this study. Satellite data are obtained from the DMSP satellites F13 (0600–1800 LT) and F15 (0900–2100 LT), respectively. Ground‐based data are obtained from the Jicamarca radar. These are then compared with numerical computations performed by the SAMI2 model for the same period. Good agreement between observation and model is achieved for the total ion concentration during daytime and nighttime, while the ion and electron temperatures agree well at night. The light ion fraction is usually <20% from all three sources except during sunrise where the light ion content can be higher. Accounting for the variables H+ and He+ concentrations in the topside appears to be the major factor affecting the different data sources.
Modeling of field‐aligned guided echoes in the plasmasphere
Authors: Fung Shing F. , Green James L.
Published: January 2005

Ray tracing modeling is used to investigate the plasma conditions under which high‐frequency (f ≫ fuh) extraordinary mode waves can be guided along geomagnetic field lines. These guided signals have often been observed as long‐range discrete echoes in the plasmasphere by the Radio Plasma Imager (RPI) onboard the Imager for Magnetopause‐to‐Aurora Global Exploration satellite. Field‐aligned discrete echoes are most commonly observed by RPI in the plasmasphere, although they are also observed over the polar cap region. The plasmasphere field‐aligned echoes appearing as multiple echo traces at different virtual ranges are attributed to signals reflected successively between conjugate hemispheres that propagate along or nearly along closed geomagnetic field lines. The ray tracing simulations show that field‐aligned ducts with as little as 1% density perturbations (depletions) and <10 wavelengths wide can guide nearly field‐aligned propagating high‐frequency X mode waves. Effective guidance of a wave at a given frequency and wave normal angle (Ψ) depends on the cross‐field density scale of the duct, such that ducts with stronger density depletions need to be wider in order to maintain the same gradient of refractive index across the magnetic field. While signal guidance by field aligned density gradient without ducting is possible only over the polar region, conjugate field‐aligned echoes that have traversed through the equatorial region are most likely guided by ducting.
Cascade spectrum of HF enhanced plasma lines generated in HF heating experiments
Authors: Kuo S. P. , Lee M. C.
Published: January 2005

Analyzed in this paper is the cascade spectrum of Langmuir waves, which are the high‐frequency sideband of the parametric decay instability or oscillating two‐stream instability excited by an O mode HF heating wave. It involves the decay of a Langmuir pump wave into a Langmuir sideband and an ion acoustic wave, which is heavily damped by ion Landau damping. Both resonant and nonresonant cascade processes are considered. The nonresonant cascade of Langmuir waves proceeds at the same location and is severely hampered by the frequency mismatch effect, because the decay wave is a driven ion mode oscillating at considerably lower frequency than that of the ion acoustic wave. In contrast, the resonant cascade, which takes place at different resonant locations to minimize the frequency mismatch effect, has to overcome the propagation loss of the mother Langmuir wave in each cascade step. The resonant cascade has a lower threshold, but the cascade lines spread over a range of altitude. The dominant factors, which determine the number of cascade lines in the radar‐detected spectrum of HF enhanced plasma lines (HFPLs), include the ion to electron temperature ratio, Ti/Te, the background plasma inhomogeneity scale length, and the heating wave field intensity. The proposed process can be a reasonable basis for explaining the radar‐measured cascade spectrum of Langmuir waves (i.e., HFPLs) in Arecibo and Tromso heating experiments.
Sporadic E morphology from GPS‐CHAMP radio occultation
Authors: Wu Dong L. , Ao Chi O. , Hajj George A. , de la Torre Juarez Manuel , Mannucci Anthony J.
Published: January 2005

The scintillations of phase and amplitude in terms of signal‐to‐noise ratio (SNR) of the GPS radio occultation signal are caused by thin ionization layers. These thin irregular electron density layers in the E region ionosphere are often called sporadic E (Es). For a monthly retrieval of Es morphology we use the variances of the phase and SNR fluctuations of worldwide ∼6000 GPS/CHAMP occultations in the E region. The Es climatology is studied globally with the SNR and phase variances in terms of monthly zonal means, seasonal maps, and diurnal and long‐term variations. The zonal mean variances reveal strong, extended Es activities at summertime midlatitudes but weak, confined activities in wintertime high latitudes, peaking at ∼105 km. Global maps at 105‐km altitude show clear dependence of Es activities on the geomagnetic dip angle, where the summertime midlatitude Es occurs mostly at dip angles of 30°–60° and the wintertime high‐latitude enhancement occurs mostly at dip angles >80°. The midlatitude Es variances exhibit a strong semidiurnal variation with peak hours near 0800–1000 and 2000 local solar time, respectively. The peak hours are delayed slightly with decreasing height, suggesting influences from the semidiurnal tide. To provide more insights on the observed SNR and phase variances, we model radio wave propagation for the CHAMP observing geometry under several perturbed cases in the E region ionosphere. The model simulations indicate that the SNR variance has the maximum response to Es perturbations at vertical wavelengths of ∼1.2 km, whereas the phase response maximizes at ∼2 km (for the 1‐s variance analysis). The characteristic scale depends little on the truncation time used in the SNR variance analysis, but it increases with the truncation time for the phase variances. Initial studies show that reasonable global Es morphology can be produced on a monthly and seasonal basis with the CHAMP one‐antenna occultations. Better results from other existing and upcoming GPS occultation missions are anticipated in future studies, and they will significantly improve our understanding of this important phenomenon.
Formation and motion of a transpolar arc in response to dayside and nightside reconnection
Authors: Milan S. E. , Hubert B. , Grocott A.
Published: January 2005

We trace the formation and subsequent motion of a transpolar arc in response to dayside and nightside reconnection. Both high‐ and low‐latitude dayside reconnection are observed, as well as periods of substorm and nonsubstorm nightside reconnection, during the 7‐hour interval of interest on 19 January 2002. We speculate that the arc is formed by a burst of nonsubstorm nightside reconnection and that its subsequent motion is controlled predominantly by the rate of dayside high‐latitude reconnection, siphoning open flux from the dusk sector polar cap to the dawn sector. The observations allow us to quantify the rates of reconnection: on the nightside, 35 and 100 kV during nonsubstorm‐ and substorm‐related bursts, respectively; on the dayside, 30 and 100 kV for high‐ and low‐latitude reconnection. The latter values give effective merging line lengths of 1 and 5.5 RE for northward and southward interplanetary magnetic field, respectively. We suggest that transpolar arc motion will be controlled not only by the By component of the IMF but also by the relative magnitude of the Bz component, when ∣By∣ > Bz motion will be dawnward for By < 0 nT and duskward for By > 0 nT; however, when Bz > ∣By∣, we expect that the arc will move toward the noon‐midnight meridian of the polar cap.
Validation of Clouds and Earth Radiant Energy System instruments aboard the Terra and Aqua satellites
Authors: Szewczyk Z. Peter , Smith G. Louis , Priestley Kory J.
Published: January 2005

A comparison of unfiltered radiances measured by Clouds and Earth Radiant Energy System (CERES) instruments (FM1 and FM4) operating on two different platforms, Terra and Aqua satellites, is presented. Data for the comparison were collected at orbital crossings in July and August 2002 and June 2003. Using a special scanning mode, viewing geometries of the instruments were matched to provide a large data set for comparing all three channels. In addition, the data collected over Greenland were used for a more stringent test of the consistency of the shortwave radiances. Statistics are computed for different scene types, and a confidence test is applied to compiled averages to show the consistency of 1% between measurements taken from the two different platforms. Results of the unfiltered radiance comparison are based on Edition2 of the FM1 and FM4 ES8 (Earth Radiation Budget Experiment–like) data product.
An algorithm for extracting zonal mean and migrating tidal fields in the middle atmosphere from satellite measurements: Applications to TIMED/SABER–measured temperature and tidal modeling
Authors: Zhu Xun , Yee Jeng‐Hwa , Talaat E. R. , Mlynczak M. , Gordley L. , Mertens C. , Russell J. M.
Published: January 2005

For a data series with grid points that do not uniformly cover a whole wave cycle in both space and time, traditional least squares fitting methods will lead to biased estimates of the zonal mean and wave components as a result of aliasing between these elements. We introduce a set of formal regularity conditions to select available grid points that reduce aliasing while obtaining the zonal mean and tidal components from unevenly sampled or incomplete measurements. The algorithm is used to self‐consistently investigate the effect of the zonal mean field on the seasonal variation of diurnal tide in the upper middle atmosphere using temperature measured by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument onboard the Thermosphere‐Ionosphere‐Mesosphere Energetics and Dynamics (TIMED) satellite. We first unbiasly derive both the zonal mean and migrating tidal components from the measurements, then simulate the seasonal variation of the migrating diurnal tide using a spectral tidal model with the measured zonal mean as input, and finally compare the seasonal variation of the measured tide with the modeled one. The model and measurement comparisons show self‐consistently and more conclusively the dominant effect of the zonal mean wind on the seasonal variation of the migrating diurnal tide in the upper middle atmosphere.
IR spectrum and radiative forcing of CF4 revisited
Authors: Hurley M. D. , Wallington T. J. , Buchanan G. A. , Gohar L. K. , Marston G. , Shine K. P.
Published: January 2005

Carbon tetrafluoride (CF4) is included as a greenhouse gas within the Kyoto Protocol. There are significant discrepancies in the reported integrated infrared (IR) absorption cross section of CF4 leading to uncertainty in its contribution to climate change. To reduce this uncertainty, the IR spectrum of CF4 was measured in two different laboratories, in 0–933 hPa of air diluent at 296 ± 2K over the wavelength range 600–3700 cm−1 using spectral resolutions of 0.03 or 0.50 cm−1. There was no discernable effect of diluent gas pressure or spectral resolution on the integrated IR absorption, and a value of the integrated absorption cross section of (1.90 ± 0.17) × 10−16 cm2 molecule−1 cm−1 was derived. The radiative efficiency (radiative forcing per ppbv) and GWP (relative to CO2) of CF4 were calculated to be 0.102 W m−2 ppbv−1 and 7200 (100 year time horizon). The GWP for CF4 calculated herein is approximately 30% greater than that given by the Intergovernmental Panel on Climate Change (IPCC) [2002] partly due to what we believe to be an erroneously low value for the IR absorption strength of CF4 assumed in the calculations adopted by the IPCC. The radiative efficiency of CF4 is predicted to decrease by up to 40% as the CF4 forcing starts to saturate and overlapping absorption by CH4, H2O, and N2O in the atmosphere increases over the period 1750–2100. The radiative forcing attributable to increased CF4 levels in the atmosphere from 1750 to 2000 is estimated to be 0.004 W m−2 and is predicted to be up to 0.033 W m−2 from 2000 to 2100, dependent on the scenario.
Erythemal UV at Davos (Switzerland), 1926–2003, estimated using total ozone, sunshine duration, and snow depth
Authors: Lindfors Anders , Vuilleumier Laurent
Published: January 2005

A method previously developed for reconstructing daily erythemal UV doses at Sodankylä, northern Finland, was adjusted to the local conditions at Davos, Switzerland, and used for estimating the erythemal UV doses there over the period 1926–2003. The method uses total ozone, sunshine duration, and snow depth as input, and is based on the empirical relationship between relative sunshine duration and relative UV doses. In order to examine how the method behaves in different environments, the relationships found for Davos and Sodankylä were compared. This revealed that the surface albedo and the cloud climate have a comparable influence on the relationship found. Although the method is fairly simple, it accounts for the most important factors affecting the amount of UV radiation reaching the Earth's surface. A comparison between estimated UV doses and the corresponding observations with a broadband biometer at Davos demonstrated the good performance of the method. The correlation coefficient for daily values varies between 0.95 and 0.98 depending on time of year, and the corresponding root mean square error is typically of the order of 20%. The monthly mean values show considerably less scatter around the regression line with a root mean square error of 4%. The time series of estimated UV shows that the UV level at Davos has varied considerably throughout the period of this study, with high values in the middle of the 1940s, in the early 1960s, and in the 1990s. Variations in the estimated UV doses prior to 1980, e.g., a steady decrease from the early 1960s to the late 1970s, were found to be caused primarily by changes in sunshine duration. Since 1980, on the other hand, there has been a distinct increase in the UV level caused mainly by the diminution of total ozone. This increase is most clearly seen during winter and spring, while the decrease from the early 1960s to the late 1970s is most pronounced during summer.
Controls of soil pipe frequency in upland blanket peat
Authors: Holden Joseph
Published: January 2005

Soil pipes were surveyed in 160 British blanket peat catchments using consistent application of ground‐penetrating radar. Soil pipes were found in all catchments. The mean frequency of piping was 69 per kilometer of surveyed transect. Land management (moorland gripping) appears to exert the most important control on hillslope pipe frequency in blanket peats. Management practice in peatlands may therefore induce more rapid subsurface erosion, carbon loss, and landform denudation via enhanced preferential flow. Topographic position is also important, with topslopes having greater pipe frequencies than footslopes, followed by midslopes with lowest frequencies. Slope gradient, however, is not a significant factor in controlling blanket peat pipe frequency. I propose that peat structural properties inherited from the way a blanket peat develops on a hillslope strongly control pipe network development. This is manifested in the way slope position appears to control pipe frequency. Aspect appears not to influence pipe frequency in blanket peats, except that it does play a weak role in catchments with annual precipitation <1500 mm. Here southwesterly facing slopes tend to have more frequent piping.
A Pliocene‐Pleistocene stack of 57 globally distributed benthic δ18O records
Authors: Lisiecki Lorraine E. , Raymo Maureen E.
Published: January 2005

We present a 5.3‐Myr stack (the “LR04” stack) of benthic δ18O records from 57 globally distributed sites aligned by an automated graphic correlation algorithm. This is the first benthic δ18O stack composed of more than three records to extend beyond 850 ka, and we use its improved signal quality to identify 24 new marine isotope stages in the early Pliocene. We also present a new LR04 age model for the Pliocene‐Pleistocene derived from tuning the δ18O stack to a simple ice model based on 21 June insolation at 65°N. Stacked sedimentation rates provide additional age model constraints to prevent overtuning. Despite a conservative tuning strategy, the LR04 benthic stack exhibits significant coherency with insolation in the obliquity band throughout the entire 5.3 Myr and in the precession band for more than half of the record. The LR04 stack contains significantly more variance in benthic δ18O than previously published stacks of the late Pleistocene as the result of higher‐resolution records, a better alignment technique, and a greater percentage of records from the Atlantic. Finally, the relative phases of the stack's 41‐ and 23‐kyr components suggest that the precession component of δ18O from 2.7–1.6 Ma is primarily a deep‐water temperature signal and that the phase of δ18O precession response changed suddenly at 1.6 Ma.
The dual PPARα/γ agonist, ragaglitazar, improves insulin sensitivity and metabolic profile equally with pioglitazone in diabetic and dietary obese ZDF rats
Authors: Pickavance Lucy C , Brand Christian L , Wassermann Karsten , Wilding John P H
Published: January 2005

In 6‐ and 10‐week‐old obesity‐prone (fa/fa) Zucker diabetic fatty (ZDF) rats, effects of prevention and intervention therapies, respectively, were compared between PPARα/γ agonist, ragaglitazar (RAGA) and separate PPARγ and α agonists, pioglitazone (PIO) and bezafibrate (BF).

In a separate study, lean (+/+) ZDF rats fed highly palatable chow to induce dietary obesity and insulin resistance were treated similarly. To test insulin‐secretory capacity, all animals underwent a hyperglycaemic clamp.

Insulin sensitivity was improved equally by RAGA and PIO in fa/fa rats subjected to both prevention and intervention treatments (e.g., prevention HOMA‐IR: −71 and −72%, respectively), as was hyperglycaemia (both −68%). BF had no effect on either parameter in any study. Plasma lipids were markedly reduced (by 48–77%) by RAGA in all studies, equivalent to PIO, but to a greater extent than BF.

RAGA improved β‐cell function (HOMA‐β) more than three‐fold with prevention and intervention therapies, whereas PIO showed improvement only in intervention therapy. Consistent with improved insulin sensitivity, glucose infusion rate during the clamp was 60% higher in RAGA‐treated animals subjected to prevention therapy, but there was little additional insulin‐secretory response, suggesting that insulin secretion was already maximal.

Thus, RAGA and PIO equally improve metabolic profile in ZDF rats, particularly when administered early in the course of diabetes. They also improve β‐cell function, although this is better demonstrated through indices incorporating fasting insulin and glucose concentrations than through the hyperglycaemic clamp technique in this model.

British Journal of Pharmacology (2005) 144, 308–316. doi:10.1038/sj.bjp.0706041
Purine‐ and pyrimidine‐induced responses and P2Y receptor characterization in the hamster proximal urethra
Authors: Pinna Christian , Glass Rainer , Knight Gillian E , Bolego Chiara , Puglisi Lina , Burnstock Geoffrey
Published: January 2005

Purine and pyrimidine compounds were investigated on hamster proximal urethral circular smooth muscle preparations. In situ hybridization studies were carried out to localize P2Y1, P2Y2, P2Y4 and P2Y6 mRNA. Protein expression was studied using Western blotting analysis with antibodies against P2Y1 and P2Y2 receptors.

The hamster urethra relaxed with an agonist potency order of: 2‐MeSADP>β,γ‐meATP=ATP=adenosine=ADP>2‐MeSATP>α,β‐meATP>TTP>CTP=UTP>GTP=UDP. The high potency of 2‐MeSADP is suggestive of an action via P2Y1 receptors. Although the order is not characteristic for any known single P2Y receptor subtype, it may represent a combination of P2Y receptor subtypes.

The selective P2Y1 receptor antagonist MRS2179 inhibited ATP‐, 2‐MeSADP‐, 2‐MeSATP‐, β,γ‐meATP‐, and to a lesser degree α,β‐meATP‐induced responses.

Adenosine, but not ATP, was inhibited by the adenosine receptor antagonist 8‐phenyltheophylline, indicating that ATP was not acting via adenosine following enzymatic breakdown.

Western blotting analysis showed the expression of both P2Y1 and P2Y2 receptors, confirming the results obtained with in situ hybridization that showed the expression of both P2Y1 and P2Y2, but not P2Y4 or P2Y6 mRNA, in smooth muscle layers of the hamster proximal urethra.

It is proposed that the relaxant response of the urethra to ATP may be evoked through the activation of the combination of receptors for P2Y1 and to a lesser extent P2Y2 receptors, which may mediate a trophic effect in addition. A P2Y subtype responsive to α,β‐meATP and P1 receptors may contribute to urethral smooth muscle relaxation.

British Journal of Pharmacology (2005) 144, 510–518. doi:10.1038/sj.bjp.0706047
Voltage‐dependent inhibition of recombinant NMDA receptor‐mediated currents by 5‐hydroxytryptamine
Authors: Kloda Anna , Adams David J
Published: January 2005

The effect of 5‐HT and related indolealkylamines on heteromeric recombinant NMDA receptors expressed in Xenopus oocytes was investigated using the two‐electrode voltage‐clamp recording technique.

In the absence of external Mg2+ ions, 5‐HT inhibited NMDA receptor‐mediated currents in a concentration‐dependent manner. The inhibitory effect of 5‐HT was independent of the NR1a and NR2 subunit combination.

The inhibition of glutamate‐evoked currents by 5‐HT was use‐ and voltage‐dependent. The voltage sensitivity of inhibition for NR1a+NR2 subunit combinations by 5‐HT was similar, exhibiting an e‐fold change per ∼20 mV, indicating that 5‐HT binds to a site deep within the membrane electric field.

The inhibition of the open NMDA receptor by external Mg2+ and 5‐HT was not additive, suggesting competition between Mg2+ and 5‐HT for a binding site in the NMDA receptor channel. The concentration‐dependence curves for 5‐HT and 5‐methoxytryptamine (5‐MeOT) inhibition of NMDA receptor‐mediated currents are shifted to the right in the presence of external Mg2+.

The related indolealkylamines inhibited glutamate‐evoked currents with the following order of inhibitory potency: 5‐MeOT=5‐methyltryptamine>tryptamine>7‐methyltryptamine>5‐HT≫tryptophan=melatonin.

Taken together, these data suggest that 5‐HT and related compounds can attenuate glutamate‐mediated excitatory synaptic responses and may provide a basis for drug treatment of excitoxic neurodegeneration.

British Journal of Pharmacology (2005) 144, 323–330. doi:10.1038/sj.bjp.0706049
The composition of the GABA receptor at the Caenorhabditis elegans neuromuscular junction
Authors: Bamber Bruce A , Richmond Janet E , Otto James F , Jorgensen Erik M
Published: January 2005

The unc‐49 gene of the nematode Caenorhabditis elegans encodes three γ‐aminobutyric acid type A (GABAA) receptor subunits. Two of these, UNC‐49B and UNC‐49C, are expressed at high abundance and co‐localize at the neuromuscular junction.

The UNC‐49B subunit is sufficient to form a GABAA receptor in vitro and in vivo. Furthermore, all loss‐of‐function unc‐49 alleles lack functional UNC‐49B. No mutations specifically inactivate UNC‐49C. Thus, UNC‐49C appears to be dispensable for receptor function; however, UNC‐49C has been conserved among different nematode species, suggesting it plays a necessary role.

To ascertain whether UNC‐49C is part of the GABAA receptor in vivo, we performed patch‐clamp electrophysiology on C. elegans muscle cells. Sensitivity to GABA, and to the antagonists picrotoxin and pregnenolone sulfate, matched the UNC‐49B/C heteromer rather than the UNC‐49B homomer, for both exogenous and synaptically‐released GABA.

The synaptic localization of UNC‐49C requires the presence of UNC‐49B, indicative of a physical association between the two subunits in vivo. Thus, the in vivo receptor is an UNC‐49B/C heteromer.

UNC‐49C plays a negative modulatory role. Using the rapid ligand‐exchange technique in vitro, we determined that UNC‐49C causes accelerated receptor desensitization. Previously, UNC‐49C was shown to reduce single‐channel conductance in UNC‐49B/C heteromers. Thus, the function of UNC‐49B is to provide GABA responsiveness and localization to synapses, while the function of UNC‐49C is to negatively modulate receptor function and precisely shape inhibitory postsynaptic currents.

British Journal of Pharmacology (2005) 144, 502–509. doi:10.1038/sj.bjp.0706052
The soy isoflavone genistein induces a late but sustained activation of the endothelial nitric oxide‐synthase system in vitro
Authors: Räthel Thomas R , Leikert Jürgen F , Vollmar Angelika M , Dirsch Verena M
Published: January 2005

Cardiovascular diseases are known as the major causes of death or disability in western countries. Decreased bioavailability of endothelial derived nitric oxide (NO) is recognized as an important promoter in cardiovascular disease.

In vivo studies suggest that phytoestrogens, especially isoflavones from soy, enhance endothelium‐dependent vasoreactivity.

We hypothesized that isoflavones may affect the expression of endothelial‐type nitric oxide synthase (eNOS) and thereby NO formation in vitro.

Human EA.hy926 endothelial cells were treated with the soybean isoflavones biochanin A and formononetin and with their metabolites genistein and daidzein. eNOS promoter activity was examined by a luciferase reporter gene assay (20 h). Active eNOS was detected by quantifying conversion of L‐arginine to L‐citrulline and by measuring NO released from endothelial cells using the fluorescent probe DAF‐2 (20–96 h).

eNOS promoter activity increased in response to isoflavone treatment (20 h). NO and L‐citrulline production by EA.hy926 cells rose up to 1.7‐fold of control levels after stimulation with genistein for 48–96 h. From these results, we conclude that the suggested positive effects of soy isoflavones on vascular reactivity may be indeed mediated via a long‐term effect on the eNOS system.

British Journal of Pharmacology (2005) 144, 394–399. doi:10.1038/sj.bjp.0706075
The expanding field of cannabimimetic and related lipid mediators
Authors: Bradshaw Heather B , Walker J Michael
Published: January 2005

The discovery of the endogenous cannabimimetic lipid mediators, anandamide and 2‐arachidonoyl glycerol, opened the door to the discovery of other endogenous lipid mediators similar in structure and function. The majority of these compounds do not bind appreciably to known cannabinoid receptors; yet some of them produce cannabimimetic effects while others exert actions through novel mechanisms that remain to be elucidated. This review explores the growing diversity of recently discovered putative lipid mediators and their relationship to the endogenous cannabinoid system. The possibility that there remain many unidentified signalling lipids coupled with the evidence that many of these yield bioactive metabolites due to actions of known enzymes (e.g. cyclooxygenases, lipoxygenases, cytochrome P450s) suggests the existence of a large and complex family of lipid mediators about which only little is known at this time. The elucidation of the biochemistry and pharmacology of these compounds may provide therapeutic targets for a variety of conditions including sleep dysfunction, eating disorders, cardiovascular disease, as well as inflammation and pain.

British Journal of Pharmacology (2005) 144, 459–465. doi:10.1038/sj.bjp.0706093
Systems analysis of RNA trafficking in neural cells
Authors: Carson John H. , Barbarese Elisa
Published: January 2005

In neural cells, certain RNAs are targeted to dendrites by a specific RNA trafficking pathway, termed the A2 pathway, mediated by the trans‐acting trafficking factor, heterogeneous nuclear ribonucleoprotein (hnRNP) A2, which binds to an 11 nucleotide cis‐acting trafficking sequence, termed the hnRNP A2 response element (A2RE). RNAs containing A2RE‐like sequences are recognized by hnRNP A2 in the nucleus and exported to the cytoplasm where they assemble into trafficking intermediates, termed granules, which also contain components of the translation machinery and molecular motors (cytoplasmic dynein and conventional kinesin). RNA granules move along microtubules to the cell periphery where they become localized and where the encoded protein is translated. Intracellular trafficking of RNA molecules by the A2 pathway is mediated by a complex system consisting of five different subsystems, ∼35 different molecules and ∼45 different molecular interactions. Specificity in the A2 pathway is provided by specific interactions of hnRNP A2 with different molecular partners in different subsystems. Polarity of RNA trafficking is controlled by transitions of trafficking intermediates between different subsystems. Comprehensive understanding of the A2 RNA trafficking pathway will require quantitative analysis of concentrations and diffusion constants for each of the different molecules, on rates and off rates for each of the different interactions, relevant conditional operators controlling specific interactions, and interactions of different subsystems. Once the necessary quantitative data are available, mathematical models for the different RNA trafficking subsystems can be developed using computational platforms such as the ‘Virtual Cell’. Here we describe how each of the subsystems in the A2 system functions and how the different subsystems interact to regulate RNA trafficking.
Termination of Epicardial Left Ventricular Tachycardia by Pacing without Global Capture
Authors: DESAI ASEEM D. , BURKE MARTIN C. , HONG THOMAS E. , KIM SUSAN , SALEM YASSER , KNIGHT BRADLEY P.
Published: January 2005

It is generally accepted that the diagnosis of an epicardial origin of ventricular tachycardia (VT) can be made indirectly by observing VT termination during ablation on the epicardial surface of the heart. There is a caveat, however, which is that termination of VT during radiofrequency current application on the epicardial surface could be due to extension of the lesion beyond the epicardium. Therefore, successful ablation of VT using an epicardial approach does not necessarily prove the reentrant circuit is located superficially. We present a case of a 44‐year‐old man with VT storm who demonstrated successful termination of VT with radiofrequency current application on the epicardial surface of the heart. This site corresponded to a site where pacing during VT resulted in termination of VT without global capture. Isolated mid‐diastolic potentials were only seen at this site as well. We hypothesize that the finding of termination of VT by pacing without global capture supports the argument that the site of pacing is a critical part of the VT circuit.
Pace Mapping of Koch's Triangle Reduces Risk of Atrioventricular Block During Ablation of Atrioventricular Nodal Reentrant Tachycardia
Authors: DELISE PIETRO , SITTA NADIR , BONSO ALDO , CORO' LEONARDO , FANTINEL MAURO , MANTOVAN ROBERTO , SCIARRA LUIGI , ZOPPO FRANCO , VERLATO ROBERTO , MARRAS ELENA , D'ESTE DANIELE
Published: January 2005

Introduction: Slow pathway (SP) ablation of AV nodal reentrant tachycardia (AVNRT) can be complicated by second‐ to third‐degree AV block. We assessed the usefulness of pace mapping of Koch's triangle in preventing this complication.

Methods and Results: Nine hundred nine consecutive patients undergoing radiofrequency ablation of AVNRT were analyzed. Group 1 (n = 487) underwent conventional slow pathway ablation. Group 2 (n = 422) underwent ablation guided by pace mapping of Koch's triangle, which located the anterogradely conducting fast pathway (AFP) based on the shortest St‐H interval obtained by stimulating the anteroseptal, midseptal, and posteroseptal aspects of Koch's triangle. In group 2, AFP was anteroseptal in 384 (91%), midseptal in 33 (7.8%), and posteroseptal or absent in 5 (1.2%). In 32 of 33 patients with midseptal AFP, slow pathway ablation was performed strictly in the posteroseptal area. In 4 of 5 patients with posteroseptal or no AFP, retrograde fast pathway was ablated. Two patients refused ablation. Persistent second‐ to third‐degree AV block was induced in 7 (1.4%) of 487 group 1 patients versus 0 (0%) of 422 group 2 patients (P = 0.038). Ablation was successful in all patients in whom ablation was performed.

Conclusion: Pace mapping of Koch's triangle identifies patients in whom the AFP is absent or is abnormally close to the slow pathway. In these cases, guiding ablation helps to avoid AV block.
Gender Differences in Electrophysiologic Effects of Mental Stress and Autonomic Tone Inhibition:
Authors: INSULANDER PER , VALLIN HANS
Published: January 2005

Introduction: Gender differences exist in electrophysiologic properties and the occurrence of certain arrhythmias. Mental stress may trigger serious arrhythmias, including ventricular tachycardias and ventricular fibrillation. This study investigates gender differences in the electrophysiologic effects on different levels of the cardiac conduction system elicited by mental stress and autonomic tone inhibition.

Methods and Results: Twenty‐three healthy volunteers (11 male and 12 female) participated in the study. Electrophysiologic and hemodynamic variables were measured at baseline, during mental stress produced by Stroop's color word conflict test (CWT), and after autonomic tone inhibition (ATI) with propranolol (0.15 mg/kg) and atropine (0.02 mg/kg). During CWT, men showed shorter QT and JT durations, whereas women had shorter refractoriness in the atrial tissue and AV node. After ATI, no gender differences in sinus nodal properties were noted, whereas AV nodal refractoriness and conduction time became shorter in women, and QT and JT duration and the refractory period of the right ventricle were shorter in men.

Conclusion: In women, mental stress produces a pronounced effect on the AV node and on the sinus node. Men react with a more pronounced effect on ventricular electrophysiologic properties. Certain gender differences in cardiac electrophysiologic properties seem to be intrinsic. After ATI, women have a higher heart rate and shorter AV nodal refractoriness but longer QT and JT intervals and longer effective refractory periods in the right ventricle. These differences may partly explain why certain arrhythmias occur more often in women than in men.
Traditional and Nonlinear Heart Rate Variability Are Each Independently Associated with Mortality after Myocardial Infarction
Authors: STEIN PHYLLIS K. , DOMITROVICH PETER P. , HUIKURI HEIKKI V. , KLEIGER ROBERT E. ,   Cast Investigators
Published: January 2005

Introduction: Decreased heart rate variability (HRV) and abnormal nonlinear HRV shortly after myocardial infarction (MI) are risk factors for mortality. Traditional HRV predicts mortality in patients with a range of times post‐MI, but the association of nonlinear HRV and outcome in this population is unknown.

Methods and Results: HRV was determined from 740 tapes recorded before antiarrhythmic therapy in Cardiac Arrhythmia Suppression Trial patients with ventricular premature contractions (VPCs) suppressed on the first randomized treatment. Patients were 70 ± 121 days post‐MI. Follow up was 362 ± 241 days (70 deaths). The association between traditional time and frequency‐domain HRV and mortality and nonlinear HRV and mortality were compared for the entire population (ALL), those without coronary artery bypass graft post‐MI (no CABG), and those without CABG or diabetes (no CABG, no DIAB) using univariate and multivariate Cox regression analysis. Strength of association was compared by P values and Wald Chi‐square values. Nonlinear HRV included short‐term fractal scaling exponent, power law slope, and SD12 (Poincaré dimension). For ALL and for no CABG, increased daytime SD12 had the strongest association with mortality (P = 0.002 ALL and P < 0.001 no CABG). For no CABG, no DIAB increased 24‐hour SD12 hours had the strongest association (P < 0.001) with mortality. Upon multivariate analysis, increased SD12, decreased ln ULF (ultra low frequency), and history of prior MI and history of congestive heart failure each remained in the model.

Conclusion: Nonlinear HRV is associated with mortality post‐MI. However, as with traditional HRV, this is diluted by CABG surgery post‐MI and by diabetes. Results suggest that decreased long‐term HRV and increased randomness of heart rate are each independent risk factors for mortality post‐MI.
Impact of Amiodarone on Electrophysiologic Properties of Pulmonary Veins in Patients with Paroxysmal Atrial Fibrillation
Authors: ROSTOCK THOMAS , SERVATIUS HELGE , RISIUS TIM , VENTURA RODOLFO , WEISS CHRISTIAN , MEINERTZ THOMAS , WILLEMS STEPHAN
Published: January 2005

Introduction: Pulmonary veins (PVs) are the predominant location of triggers for atrial fibrillation (AF), but little is known about the electrophysiologic properties of PVs. In addition, the influence of amiodarone on the electrophysiologic properties of PVs has not been elucidated.

Methods and Results: Fifty‐five patients with symptomatic and drug‐resistant AF were divided into two groups: group 1 patients (n = 29) without antiarrhythmic drug therapy at the time of electrophysiologic study (EPS), and group 2 patients (n = 26) undergoing continuous long‐term treatment with amiodarone. EPS including programmed stimulation of both atria and within the PVs was performed in both groups. In group 1, the effective refractory period (ERP) of all PVs (174 ± 62 msec) was significantly shorter than the ERP of the left atrium ([LA] 254 ± 30 msec, P = 0.0001) and right atrium ([RA] 221 ± 29 msec, P = 0.0001). The same pattern was observed in group 2 (PV: 210 ± 58 msec; LA: 259 ± 35 msec, P = 0.0001; RA: 246 ± 37 msec, P = 0.0255). The ERP of all stimulated PVs was significantly lower in group 1 (174 ± 62 msec) than in group 2 (210 ± 58 msec; P = 0.0001). The ERP of the left superior and right superior PVs and RA but not the left inferior PV and LA were significantly increased in patients treated with amiodarone. Decremental conduction properties were observed in all stimulated PVs, and there were no significantly differences between the maximal decrement of both groups.

Conclusion: The distinctive electrophysiologic properties of PVs are emphasized by amiodarone therapy. Long‐term amiodarone treatment is responsible for heterogeneous alteration of the PV electrophysiology, which may account for the individual antiarrhythmic responses in a subset of patients with paroxysmal AF.
Transition-metal profiles in a multicrystalline silicon ingot
Authors: Macdonald Daniel , Cuevas Andrés , Kinomura A. , Nakano Y. , Geerligs L. J.
Published: January 2005

The concentrations of transition-metal impurities in a photovoltaic-grade multicrystalline silicon ingot have been measured by neutron activation analysis. The results show that the concentrations of Fe, Co, and Cu are determined by segregation from the liquid-to-solid phase in the central regions of the ingot. This produces high concentrations near the top of the ingot, which subsequently diffuse back into the ingot during cooling. The extent of this back diffusion is shown to correlate to the diffusivity of the impurities. Near the bottom, the concentrations are higher again due to solid-state diffusion from the crucible after crystallization has occurred. Measurement of the interstitial Fe concentration along the ingot shows that the vast majority of the Fe is precipitated during ingot growth. Further analysis suggests that this precipitation occurs mostly through segregation to extrinsic defects at high temperature rather than through solubility-limit-driven precipitation during ingot cooling.
Role of interfacial charge in the piezoelectric properties of ferroelectric 0-3 composites
Authors: Wong C. K. , Shin F. G.
Published: January 2005

We investigated the effects of compensating charges (at the inclusion-matrix interface) on the piezoelectric properties of ferroelectric 0-3 composites. Our previously developed model [C. K. Wong, Y. M. Poon, and F. G. Shin, J. Appl. Phys. 90, 4690 (2001)] has been extended to include the additional contribution from the deformation of the inclusion particles due to the applied stress in the piezoelectric measurement. The relative significance of this contribution is mainly determined by the amount of compensating interfacial charge, which is significantly governed by the degrees of poling of the constituent materials in the composite sample. This model provides an explanation to an anomaly in the piezoelectric coefficients of 0-3 composite samples with the matrix and inclusion phases polarized in opposite directions. Explicit expressions in closed form have been derived for the effective d33, d31, and dh coefficients. After taking into consideration the degree of poling of the constituents and the effects of the compensating interfacial charges, theoretical predictions show good agreement with published experimental data. Goodness of fit is not limited to low volume concentration of inclusions.
Electrical characterization of p-GaAs epilayers disordered by doped spin-on-glass
Authors: Deenapanray P. N. K. , Petravic M. , Jagadish C. , Krispin M. , Auret F. D.
Published: January 2005

Impurity-free disordering (IFD) of uniformly doped p-GaAs epitaxial layers was achieved using either undoped or doped (Ga or P) spin-on-glass (SOG) in conjunction with rapid thermal annealing in the temperature range from 800to925°C. Capacitance-voltage measurements showed a pronounced increase in the doping concentration (NA) in the near-surface region of the layers disordered using both undoped and P:SOG. The increase in NA showed an Arrhenius-like dependence on the inverse of annealing temperature. On the other hand, NA did not change significantly for Ga-doped SOG. These changes can be explained by the relative injection of excess gallium vacancies (VGa) during IFD of p-GaAs by the different SOG layers. Deep-level transient spectroscopy showed a corresponding increase in the concentration of a defect HA (EV+0.39eV), which can be attributed to Cu, in the undoped and P:SOG disordered p-GaAs layers, but not in the epilayers disordered by Ga:SOG. We have explained the increase in free carrier concentration by the segregation of Zn atoms towards the surface during the injection of VGa. The redistribution of Zn during disordering of buried marker layers in GaAs and Al0.6Ga0.4As using either undoped or Ga-doped SOG was verified by secondary-ion mass spectrometry.
Surface profile of material ablated with high-power lasers in ambient air medium
Authors: Vatsya S. R. , Li C. , Nikumb S. K.
Published: January 2005

In general, material processing with high-power ultra-short-pulsed lasers yields cleaner surfaces, as long as the intensity profile of the laser beam is well shaped. However, the beam suffers distortions during propagation through ambient atmospheric media such as air. Passage through such media causes the beam to self-focus, increasing the intensity further and causing the breakdown of the gas. The resulting plasma distorts the beam’s original profile and the ablated surface conforms to the beam profile. A numerical scheme is developed here to calculate the intensity profile of an optical beam propagating through a medium. Intensity distribution of the beam is then used to determine the profile of the processed surface by a geometrical method developed recently. The calculated profile is compared with the experimentally obtained surface with good agreement. For medium spot sizes, the self-focusing and plasma effects tend to cancel each other, maintaining the intensity profile of the beam similar to the original Gaussian distribution. For small spot sizes when the intensity is high, the plasma effects are found to distort the beam profile. This indicates that the experimental parameters can be adjusted to improve the quality of the machined surface.
On the mechanisms of epitaxial island alignment on patterned substrates
Authors: Kukta R. V. , Kouris D.
Published: January 2005

A recent approach to fabricating self-assembled epitaxial nanostructures involves the use of topographically patterned substrates to control the formation of material deposits during growth. This article investigates the energetic and kinetic mechanisms that guide the positioning of strained epitaxial islands in these systems. A continuum-level model is used wherein the free energy of system consists of surface energy and strain energy. The substrate shape is represented by small amplitude sinusoidal features. An energetic phase diagram is calculated to determine which sites are most favorable—peaks, valleys, or side walls—depending on factors as substrate shape, lattice mismatch, surface energy, and the amount of material deposited. The kinetic evolution through the processes of deposition and surface diffusion is then simulated. It is found that the resulting morphology depends largely on the rate of deposition relative to surface mobility. Relatively slow deposition rates produce configurations of minimum free energy while higher deposition rates give rise to novel metastable states. Mechanisms by which various configurations arise are discussed in detail. Results are found to be in excellent agreement with published experiments.