bluuebunny/crossref_metadata_2025 huggingface dataset:
DIVISION X / COMMISSION 40 / WORKING GROUP GLOBAL VERY LONG BASELINE INTERFEROMETRY
Authors: Romney Jonathan D. , Schilizzi Richard T. , Garrington Simon T. , Gurvits Leonid I. , Hong Xiaoyu , Jauncey David L. , Kobayashi Hideyuki , Porcas Richard , Preston Robert A. , Salter Christopher John , Szomoru Arpad , Tsuboi Masato , Ulvestad James S. , Whitney Alan R.
Published: January 2009

This triennium began with an action to re-create the Terms of Reference for the Working Group Global VLBI (WG-GV). These had been lost over the years since the Group was established in 1990. Fortunately, the personal archive of one long-term member yielded a copy of the original memorandum by R. D. Ekers, which was found to coincide quite well with current practice and areas of interest. New Terms of Reference, based on modern conditions, were drafted and accepted by both IAU and URSI.
INTER-DIVISION IX-X-XI WORKING GROUP ASTRONOMY FROM THE MOON
Authors: Baliunas Sallie L. , Kondo Yoji , Kaifu Norio , Engvold Oddbjørn , Kaifu Norio , Okuda Haruyuki , Terzian Yervant
Published: January 2009

During the period the Working Group had proposed and was granted renewed status by Division XI Space and High-Energy Astrophysics. Additionally the Working Group requested to be extended to Division IX Optical and Infrared Techniques, Division X Radio Astronomy, as well as Division XI.
DIVISION XII / COMMISSION 5 / WORKING GROUP ASTRONOMICAL DATA
Authors: Norris Raymond P.
Published: January 2009

Astronomers are well aware of the changing nature, volume, and complexity of astronomical data. Most of us are aware that next generation instruments, with Terabyte databases, are going to present enormous challenges to the way that we process data, and our current ways of managing astronomical databases will probably no longer work. So there are a number of initiatives within the astronomical community, most notably the Virtual Observatory, which aim to address these. However, many astronomers are not aware that similar challenges are being met in other disciplines (e.g., geosciences, life sciences, etc.) and that similar solutions are being sought. As a result, astronomy has much to gain from cross-fertilisation with other disciplines.
DIVISION XII / COMMISSION 5 / WORKING GROUP FITS DATA FORMAT
Authors: Pence William D. , Ochsenbein François , Wells Donald C. , Allen Steven W. , Calabretta Mark R. , Chiappetti Lucio , Durand Daniel , Forveille Thierry , Gabriel Carlos , Greisen Eric , Grosbol Preben J. , Hanisch Robert J. , Jaffe Walter J. , Kanamitsu Osamu , Malkov Oleg Yu. , Page Clive G. , Rots Arnold H. , Shaw Richard A. , Stobie Elizabeth , Thompson William T. , Tody Douglas C. , Wicenec Andreas
Published: January 2009

The Working Group FITS (WG-FITS) is the international control authority for the Flexible Image Transport System (FITS) data format. The WG-FITS was formed in 1988 by a formal resolution of the IAU XX General Assembly in Baltimore (MD, USA), 1988, to maintain the existing FITS standards and to approve future extensions to FITS.
COMMISSION 14: ATOMIC AND MOLECULAR DATA
Authors: Federman Steven R. , Wahlgren Glenn M. , Johansson Sveneric , Dimitrijevic Milan , Jorissen Alain , Mashonkina Lyudmilla I. , Salama Farid , Tennyson Jonathan , van Dishoeck Ewine F.
Published: January 2009

The main purpose of Commission 14 is to foster interactions between the astronomical community and those conducting research on atoms, molecules and solid state particles. One way the Commission accomplishes this goal is through triennial compilations on recent relevant research in atomic, molecular and solid state physics, as well as related chemical fields. The most recent compilations appear in the following set of WG Triennial Reports, which were produced by members of the Working Groups and the Organizing Committee of Commission 14. Before presenting the Reports, we highlight the meetings supported by the Commission.
DIVISION XII / COMMISSION 46 / PROGRAM GROUP INTERNATIONAL SCHOOLS FOR YOUNG ASTRONOMERS
Authors: De Greve Jean-Pierre , Leung Kam-Ching , Gerbaldi Michèle
Published: January 2009

The IAU Commission 46 Program Group International Schools for Young Astronomers (ISYA) was created in 1967 (Gerbaldi 2008). During the period 2006 till August 2008 two ISYAs took place, one in Malaysia and a second one in Turkey.
EXECUTIVE COMMITTEE PRESS OFFICE
Authors: Christensen Lars Lindberg
Published: January 2009

While expecting a huge increase of interest in the IAU as a result of the planet definition issue on the agenda of the IAU XXVI General Assembly, Prague, Czech Republic, August 2006, the Executive Committee appointed Lars Lindberg Christensen as Press Officer in June 2006. He will stay on the job till at least the IAU XXVII General Assembly in Rio de Janeiro, Brazil, August 2009.
Prävention kindlichen Übergewichts
Authors: Warschburger Petra , Richter Maria
Published: January 2009

Zusammenfassung. Adipositas ist ein ernstzunehmendes gesundheitliches Problem, welches das physische und psychosoziale Wohlbefinden von Kindern und deren Eltern beeinträchtigt und somit wirksamer präventiver Ansätze bedarf. Dabei ist es bedeutsam, welche Barrieren, Anreize und Selbstwirksamkeitserwartungen Eltern für oder gegen die Teilnahme an solchen Programmen entscheiden lassen. Ziel der Studie war es zu untersuchen, wie Mütter ihre Selbstwirksamkeits- und Handlungsergebniserwartungen beschreiben und inwieweit sich soziodemografische Aspekte auf diese Einschätzungen auswirken. Insgesamt wurden 219 Mütter von Kindern im Alter von 3–6 Jahren befragt. Mehr als die Hälfte der befragten Mütter waren übergewichtig bzw. adipös sowie 12% der Kinder. Es ergaben sich weder für das Alter und das Geschlecht des Kindes noch für das Familieneinkommen Unterschiede in den Handlungsergebniserwartungen. Mütter mit geringerer Bildung nahmen weniger Anreize wahr und Mütter mit übergewichtigen Kindern sahen weniger Barrieren für eine Programmteilnahme. Übergewichtige Mütter dagegen bewerteten die Barrieren und Anreize höher als normalgewichtige Mütter. Hinsichtlich der Selbstwirksamkeit ergaben sich ebenfalls Unterschiede bezüglich der Bildung und des Gewichts der Mutter sowie des Kindes. Im Vorfeld einer Intervention sollte ein Beratungsgespräch bezogen auf die mütterlichen Erwartungen stattfinden, um die Teilnahmebereitschaft und den Programmerfolg zu unterstützen.
Low‐temperature magnetic properties of greigite (Fe3S4)
Authors: Chang Liao , Roberts Andrew P. , Rowan Christopher J. , Tang Yan , Pruner Petr , Chen Qianwang , Horng Chorng‐Shern
Published: January 2009

We provide comprehensive low‐temperature magnetic results for greigite (Fe3S4) across the spectrum from superparamagnetic (SP) to multidomain (MD) behavior. It is well known that greigite has no low‐temperature magnetic transitions, but we also document that it has strong domain‐state dependence of magnetic properties at low temperatures. Blocking of SP grains and increasing thermal stability with decreasing temperature is apparent in many magnetic measurements. Thermally stable single‐domain greigite undergoes little change in magnetic properties below room temperature. For pseudo‐single‐domain (PSD)/MD greigite, hysteresis properties and first‐order reversal curve diagrams exhibit minor changes at low temperatures, while remanence continuously demagnetizes because of progressive domain wall unpinning. The low‐temperature demagnetization is grain size dependent for PSD/MD greigite, with coarser grains undergoing larger remanence loss. AC susceptibility measurements indicate consistent blocking temperatures (TB) for all synthetic and natural greigite samples, which are probably associated with surficial oxidation. Low‐temperature magnetic analysis provides much more information about magnetic mineralogy and domain state than room temperature measurements and enables discrimination of individual components within mixed magnetic mineral assemblages. Low‐temperature rock magnetometry is therefore a useful tool for studying magnetic mineralogy and granulometry of greigite‐bearing sediments.
Rapid recent warming on Rutford Ice Stream, West Antarctica, from borehole thermometry
Authors: Barrett B. E. , Nicholls K. W. , Murray T. , Smith A. M. , Vaughan D. G.
Published: January 2009

The Antarctic Peninsula has warmed faster than the global average rate of warming during the last century. Due to limited availability of long term meteorological records, the geographical extent of this rapid warming is poorly defined. We collected borehole temperature measurements in the upper 300 m of Rutford Ice Stream, West Antarctica, and employed an inverse modeling scheme with a heat diffusion‐advection equation to determine the recent surface temperature history of the borehole position. Our results reveal recent warming of 0.17 ± 0.07°C (decade)−1 since 1930. This result suggests that, at least in an attenuated form, the rapid warming observed over the Antarctic Peninsula extends as far south as Rutford Ice Stream. This result agrees with other recent results that show a warming trend across much of the West Antarctic Ice Sheet.
Radar evidence for ice in lobate debris aprons in the mid‐northern latitudes of Mars
Authors: Plaut Jeffrey J. , Safaeinili Ali , Holt John W. , Phillips Roger J. , Head James W. , Seu Roberto , Putzig Nathaniel E. , Frigeri Alessandro
Published: January 2009

Subsurface radar sounding data indicate that lobate debris aprons found in Deuteronilus Mensae in the mid‐northern latitudes of Mars are composed predominantly of water ice. The position in time delay and the relatively low amount of signal loss of the apparent basal reflectors below the debris aprons indicate that aprons contain only a minor component of lithic material. The current presence of large ice masses at these latitudes has important implications for the climate evolution of Mars, and for future targets for in situ exploration.
Standing Alfvén waves at the magnetopause
Authors: Plaschke F. , Glassmeier K.‐H. , Auster H. U. , Constantinescu O. D. , Magnes W. , Angelopoulos V. , Sibeck D. G. , McFadden J. P.
Published: January 2009

We present results from a statistical analysis of the oscillatory motion of the magnetopause based on THEMIS spacecraft observations, yielding the first experimental evidence for the existence of standing Alfvénic surface or Kruskal‐Schwarzschild modes at the magnetopause. The magnetopause boundary represents a membrane under tension, which may resonantly interact with magnetospheric cavity or waveguide modes. Ultra‐low “magic” geomagnetic pulsation frequencies, often observed in ground‐based and ionospheric measurements and attributed to these cavity or waveguide modes, agree with the detected magnetopause oscillation frequencies and are reinterpreted in terms of surface mode eigenfrequencies.
Global hybrid simulations: Foreshock waves and cavitons under radial interplanetary magnetic field geometry
Authors: Blanco‐Cano X. , Omidi N. , Russell C. T.
Published: January 2009

We use global hybrid (kinetic ions and fluid electrons) simulations to study the solar wind interaction with the magnetosphere for a radial (θvB = 0) interplanetary magnetic field (IMF) geometry. Global hybrid simulations provide a collective picture of processes taking place in the foreshock, bow shock, and magnetosheath. Because ions are treated as particles, these codes also give information on ion‐scale microphysics. Under radial IMF geometry, the foreshock forms in front of the dayside magnetosphere, and the plasma convecting downstream is very perturbed. The foreshock is permeated by weakly compressive ultralow frequency (ULF) waves that propagate at angles up to 30° to the ambient field. These weakly compressive waves are generated by field‐aligned ions. Wave‐Particle interaction results in ion scattering, while wave amplitude grows and fluctuations become compressive as they approach the shock. While weakly compressive waves are dominant far from the shock, a second population of ULF fluctuations arises close to it. These fast magnetosonic waves propagate at large angles to the magnetic field and are linearly polarized. We find that, in addition to the ULF waves, large depressions in density and magnetic field magnitude form near the shock. These density cavitons or depressions are bounded by enhanced magnetic fields, and inside them, hot diffuse ions are present. Foreshock density cavitons in our simulations are embedded in regions with ULF activity, which is in contrast to the isolated character of “foreshock cavities” reported previously. We show that density cavitons form due to the nonlinear interaction of the two types of waves present in the foreshock. Wave interaction also modifies the characteristics of weakly compressive waves. A comparison of our results with Cluster observations reveals that the characteristics of weakly compressive waves in our simulation resemble the properties of right‐handed 30‐s waves found in the terrestrial foreshock. Likewise, we show the existence of density cavitons, or depressions, in regions of Earth's foreshock permeated by ULF waves. The properties of these observed Cluster cavitons are similar to the ones we find in the simulations.
Energetic ion spectral characteristics in the Saturnian magnetosphere using Cassini/MIMI measurements
Authors: Dialynas K. , Krimigis S. M. , Mitchell D. G. , Hamilton D. C. , Krupp N. , Brandt P. C.
Published: January 2009

We report sample results on Saturn magnetospheric energetic ion spectral shapes using measurements obtained from the Magnetospheric Imaging Instrument (MIMI) suite onboard Cassini. The ion intensities are measured by the Charge Energy Mass Spectrometer (CHEMS) that covers the energy range of 3 to 236 keV/e, the Low Energy Magnetospheric Measurements System (LEMMS) covering the energy range of 0.024 < E < 18 MeV, and the Ion Neutral Camera (INCA) that provides ion measurements in the ion mode at the energy range ∼5.5 to >220 keV for protons. The data used cover several passes from the period 1 July 2004 to 10 April 2007, at various latitudes over the dipole L range 5 < L < 20 RS. The spectra generally show a power law in energy form at larger L values but display a flattening/relative peak at lower (L < 10) values centered at ∼50 to ∼100 keV and can be fit by a κ distribution function with characteristic kT ranging from ∼10 to ∼100 keV. The results are consistent with the assumption that energetic protons are heated adiabatically as they move inward to stronger magnetic fields, in contrast to the singly ionized oxygen that seems to be heated locally at each L shell. The lack of any trend of the O+ temperature versus L shell implies that nonadiabatic energization mechanisms and charge exchange with Saturn's neutral gas cloud play an important role for ion energetics.
Quantifying uncertainty in mean earthquake interevent times for a finite sample
Authors: Naylor M. , Main I. G. , Touati S.
Published: January 2009

Seismic activity is routinely quantified using means in event rate or interevent time. Standard estimates of the error on such mean values implicitly assume that the events used to calculate the mean are independent. However, earthquakes can be triggered by other events and are thus not necessarily independent. As a result, the errors on mean earthquake interevent times do not exhibit Gaussian convergence with increasing sample size according to the central limit theorem. In this paper we investigate how the errors decay with sample size in real earthquake catalogues and how the nature of this convergence varies with the spatial extent of the region under investigation. We demonstrate that the errors in mean interevent times, as a function of sample size, are well estimated by defining an effective sample size, using the autocorrelation function to estimate the number of pieces of independent data that exist in samples of different length. This allows us to accurately project error estimates from finite natural earthquake catalogues into the future and promotes a definition of stability wherein the autocorrelation function is not varying in time. The technique is easy to apply, and we suggest that it is routinely applied to define errors on mean interevent times as part of seismic hazard assessment studies. This is particularly important for studies that utilize small catalogue subsets (fewer than ∼1000 events) in time‐dependent or high spatial resolution (e.g., for catastrophe modeling) hazard assessment.
Effects of small‐scale features and local wind forcing on tracer dispersion and estimates of population connectivity in a regional scale circulation model
Authors: Rasmussen L. L. , Cornuelle B. D. , Levin L. A. , Largier J. L. , Di Lorenzo E.
Published: January 2009

A small‐scale model of the Southern California–Northern Baja California coastline has been developed to explore dispersion over the continental shelf, with specific attention to physical parameters pertinent to simulations of larval dispersal and population connectivity. The ROMS simulation employs a nested grid system, with an inner domain resolution of 600 m and an outer domain resolution of 1.5 km. Realistic bathymetry and forcing were employed to investigate the effects of passive transport of tracers introduced at locations with known communities of mytilid mussels along the coastline. The effects of topographic resolution, boundary conditions, and choice of meteorological forcing products on dispersion rates, tracer trajectories, and the subsequent measures of population connectivity were examined. In particular, the choice of wind forcing product resulted in different circulation patterns and tracer trajectories and had especially important consequences on measures of larval connectivity such as self‐seeding, potential for larval settlement (import), and contribution to the pool of available larvae (export). While some forcing products performed better when model data were compared to field measurements, no product was clearly superior. The uncertainty in results, which may appear minor in larger‐scale temperature or surface velocity fields, is significant when examining a sensitive passive tracer. This modeling uncertainty needs to be addressed when interpreting connectivity results.
Cloud ice: A climate model challenge with signs and expectations of progress
Authors: Waliser Duane E. , Li Jui‐Lin F. , Woods Christopher P. , Austin Richard T. , Bacmeister Julio , Chern Jiundar , Del Genio Anthony , Jiang Jonathan H. , Kuang Zhiming , Meng Huan , Minnis Patrick , Platnick Steve , Rossow William B. , Stephens Graeme L. , Sun‐Mack Szedung , Tao Wei‐Kuo , Tompkins Adrian M. , Vane Deborah G. , Walker Christopher , Wu Dong
Published: January 2009

Present‐day shortcomings in the representation of upper tropospheric ice clouds in general circulation models (GCMs) lead to errors in weather and climate forecasts as well as account for a source of uncertainty in climate change projections. An ongoing challenge in rectifying these shortcomings has been the availability of adequate, high‐quality, global observations targeting ice clouds and related precipitating hydrometeors. In addition, the inadequacy of the modeled physics and the often disjointed nature between model representation and the characteristics of the retrieved/observed values have hampered GCM development and validation efforts from making effective use of the measurements that have been available. Thus, even though parameterizations in GCMs accounting for cloud ice processes have, in some cases, become more sophisticated in recent years, this development has largely occurred independently of the global‐scale measurements. With the relatively recent addition of satellite‐derived products from Aura/Microwave Limb Sounder (MLS) and CloudSat, there are now considerably more resources with new and unique capabilities to evaluate GCMs. In this article, we illustrate the shortcomings evident in model representations of cloud ice through a comparison of the simulations assessed in the Intergovernmental Panel on Climate Change Fourth Assessment Report, briefly discuss the range of global observational resources that are available, and describe the essential components of the model parameterizations that characterize their “cloud” ice and related fields. Using this information as background, we (1) discuss some of the main considerations and cautions that must be taken into account in making model‐data comparisons related to cloud ice, (2) illustrate present progress and uncertainties in applying satellite cloud ice (namely from MLS and CloudSat) to model diagnosis, (3) show some indications of model improvements, and finally (4) discuss a number of remaining questions and suggestions for pathways forward.
Interpreting 10Be changes during the Maunder Minimum
Authors: Field Christy V. , Schmidt Gavin A. , Shindell Drew T.
Published: January 2009

Beryllium‐10 archives are important resources for understanding how solar activity may have varied in the past. Climate simulations using the Goddard Institute for Space Studies ModelE general circulation model are used to calibrate the impacts of production changes, solar forcings, and volcanic aerosol forcing on 10Be concentration during periods such as the Maunder Minimum (1645–1715 A.D.). We find that for the preindustrial period, production‐related 10Be changes are the dominant signal in snow concentration, and that the effects of both solar and volcanic forcings on climate are relatively minor. Ambiguities in determining the observed changes in 10Be snow concentration during the Maunder Minimum complicate the process of estimating changes in the solar modulation strength during that time. Given those limitations, we estimate that the average value of the solar modulation parameter ϕ was between 280 and 395 MeV over the course of the Maunder Minimum, and was approximately 142 MeV during the years of peak 10Be concentration as recorded in the Dye 3 and South Pole ice core records.
Volcano Deformation and Gravity Workshop Synopsis and Outcomes: The 2008 Volcano Deformation and Temporal Gravity Change Workshop; Vancouver, Washington, 13–15 May 2008
Authors: Dzurisin Daniel , Lu Zhong
Published: January 2009

A volcano workshop was held in Washington State, near the U.S. Geological Survey (USGS) Cascades Volcano Observatory. The workshop, hosted by the USGS Volcano Hazards Program (VHP), included more than 40 participants from the United States, the European Union, and Canada. Goals were to promote (1) collaboration among scientists working on active volcanoes and (2) development of new tools for studying volcano deformation. The workshop focused on conventional and emerging techniques, including the Global Positioning System (GPS), borehole strain, interferometric synthetic aperture radar (InSAR), gravity, and electromagnetic imaging, and on the roles of aqueous and magmatic fluids.
Plankton Functional Types in a New Generation of Biogeochemical Models: Integration of Plankton Abundance Data for the Evaluation of Marine Biogeochemical Models; Cambridge, United Kingdom, 1–3 October 2008
Authors: Le Quéré Corinne , Pesant Stéphane
Published: January 2009

It has long been recognized that biological activity has a large influence on biogeochemical cycles in the ocean. However, the recognition that the ecosystem composition may also be significant is more recent. The newest generation of biogeochemical models used to study climate‐ocean interactions represents the diversity of planktonic ecosystems by grouping similar species into “plankton functional types” (PFTs). These models can thus include specific biogeochemical processes mediated by distinct PFTs, such as the ballasting effect of mineral shells, the aggregation effect of some organic material, and the packaging effect of grazing by large zooplankton.
Portrait of Waldo Smith
Authors: Spilhause Fred
Published: January 2009

In 1944, Waldo Smith was looking for a place where he could make a difference. He had taught in universities in the United States and Turkey, and he had worked as an engineer in the field of hydrology in the United States. Somehow, a chance meeting with John Adam Fleming, AGU's long‐time General Secretary, led to Waldo's becoming the first executive officer employed by the Union. That, in turn, brought him the opportunity to make a difference.
Active Dilation of Penetrating Arterioles Restores Red Blood Cell Flux to Penumbral Neocortex after Focal Stroke
Authors: Shih Andy Y , Friedman Beth , Drew Patrick K , Tsai Philbert S , Lyden Patrick D , Kleinfeld David
Published: January 2009

Pial arterioles actively change diameter to regulate blood flow to the cortex. However, it is unclear whether arteriole reactivity and its homeostatic role of conserving red blood cell (RBC) flux remains intact after a transient period of ischemia. To examine this issue, we measured vasodynamics in pial arteriole networks that overlie the stroke penumbra during transient middle cerebral artery occlusion in rat. In vivo two-photon laser-scanning microscopy was used to obtain direct and repeated measurements of RBC velocity and lumen diameter of individual arterioles, from which the flux of RBCs was calculated. We observed that occlusion altered surface arteriole flow patterns in a manner that ensured undisrupted flow to penetrating arterioles throughout the imaging field. Small-diameter arterioles (< 23 µm), which included 88% of all penetrating arterioles, exhibited robust vasodilation over a 90-min occlusion period. Critically, persistent vasodilation compensated for an incomplete recovery of RBC velocity during reperfusion to enable a complete restoration of postischemic RBC flux. Further, histologic examination of tissue hypoxia suggested re-oxygenation through all cortical layers of the penumbra. These findings indicate that selective reactivity of small pial arterioles is preserved in the stroke penumbra and acts to conserve RBC flux during reperfusion.
The permissive role of mitochondria in the induction of haem oxygenase-1 in endothelial cells
Authors: Ricart Karina C. , Bolisetty Subhashini , Johnson Michelle S. , Perez Jessica , Agarwal Anupam , Murphy Michael P. , Landar Aimee
Published: January 2009

HO-1 (haem oxygenase 1) is an essential antioxidant enzyme in the cell that exerts its effects through removal of pro-oxidant haem groups and the formation of antioxidant molecules and carbon monoxide. The electrophilic cyclopentenone 15d-PGJ2 (15-deoxy-Δ12,14-prostaglandin J2) induces the expression of HO-1 protein through the covalent modification of protein thiols. It has been shown that specific thiol residues of the redox-sensor Keap1 (Kelch-like ECH-associated protein 1) are modified by 15d-PGJ2, leading to activation of the transcription factor Nrf-2 (nuclear factor-erythroid 2 p45 subunit-related factor 2) and up-regulation of genes under control of the electrophile-response element, including HO-1. However, 15d-PGJ2 has also been shown to modify other proteins which comprise the electrophile-responsive proteome. Since 15d-PGJ2 has been shown to localize to the mitochondria in endothelial cells, we hypothesized that mitochondrial protein modification may also be important in Keap1/Nrf-2 signal transduction, leading to HO-1 up-regulation. In order to determine the role of mitochondrial protein thiol modification in HO-1 induction, we used the mitochondrial-targeted thiol-reactive compound IBTP [(4-iodobutyl)triphenylphosphonium]. IBTP had no effect on basal HO-1 levels, but effectively blocked HO-1 induction by a variety of reagents including haemin, iodoacetamide and 15d-PGJ2. Mechanistically, IBTP did not prevent the covalent modification of Keap1 by 15d-PGJ2. However, IBTP prevented the 15d-PGJ2-dependent increases in HO-1 mRNA and protein. Furthermore, IBTP prevented the nuclear accumulation of Nrf-2, suggesting cross-talk between mitochondria and antioxidant-response signal transduction. This effect was independent of reactive oxygen species formation or mitochondrial membrane potential. In addition, IBTP significantly enhanced the toxicity of high concentrations of 15d-PGJ2, suggesting that loss of mitochondrial control of HO-1 leads to increased susceptibility to electrophilic stress in endothelial cells. The implications for these studies in understanding the balance between cytoprotection and cytotoxicity in the context of diseases such as atherosclerosis is discussed.
Mechanisms of chemokine and antigen-dependent T-lymphocyte navigation
Authors: Ward Stephen G. , Marelli-Berg Federica M.
Published: January 2009

T-lymphocyte trafficking is targeted to specific organs by selective molecular interactions depending on their differentiation and functional properties. Specific chemokine receptors have been associated with organ-specific trafficking of memory and effector T-cells, as well as the recirculation of naïve T-cells to secondary lymphoid organs. In addition to the acquisition of tissue-selective integrins and chemokine receptors, an additional level of specificity for T-cell trafficking into the tissue is provided by specific recognition of antigen displayed by the endothelium involving the TCRs (T-cell antigen receptors) and co-stimulatory receptors. Activation of PI3K (phosphoinositide 3-kinase) is a robust signalling event shared by most chemokine receptors as well as the TCR and co-stimulatory receptors, contributing to several aspects of T-lymphocyte homing as well as actin reorganization and other components of the general migratory machinery. Accordingly, inhibition of PI3K has been considered seriously as a potential therapeutic strategy by which to combat various T-lymphocyte-dependent pathologies, including autoimmune and inflammatory diseases, as well as to prevent transplant rejection. However, there is substantial evidence for PI3K-independent mechanisms that facilitate T-lymphocyte migration. In this regard, several other signalling-pathway components, including small GTPases, PLC (phospholipase C) and PKC (protein kinase C) isoforms, have also been implicated in T-lymphocyte migration in response to chemokine stimulation. The present review will therefore examine the PI3K-dependent and -independent signal-transduction pathways involved in T-cell migration during distinct modes of T-cell trafficking in response to either chemokines or the TCR and co-stimulatory molecules.
A role for the syntaxin N-terminus
Authors: Munson Mary , Bryant Nia J.
Published: January 2009

Intracellular membrane fusion steps in eukaryotes require the syntaxin family of SNARE (soluble N-ethylmaleimide-sensitive fusion protein-attachment protein receptor) proteins. Syntaxins are regulated at several levels through interactions with regulatory proteins, including the SM (Sec1p/Munc18) proteins. Key to understanding this regulation is the characterization of different SM–syntaxin binding interactions at the molecular level and in terms of their contribution to function in vivo. The most conserved SM–syntaxin binding mode is through interaction of the syntaxin's extreme N-terminal peptide with a hydrophobic pocket on the surface of the SM protein. Surprisingly, mutant versions of two different SM proteins abrogated for this binding display no discernable phenotypes in vivo. In this issue of the Biochemical Journal, Johnson et al. demonstrate that loss of the N-terminal binding interaction between the syntaxin UNC-64 and the SM protein UNC-18 severely impairs neuromuscular synaptic transmission in Caenorhabditis elegans, resulting in an unco-ordinated phenotype. In contrast, loss of a second mode of SM–syntaxin binding has no detectable effect. Collectively, these results suggest that, although different membrane trafficking steps are all regulated by SM–syntaxin interactions using similar binding modes, they are differentially regulated, highlighting the need for careful dissection of the binding modes.
Comparison of the retinal microvasculature in European and African-Caribbean people with diabetes
Authors: Mahal Sharleet , Strain W. David , Martinez-Perez M. Elena , Thom Simon A. McG. , Chaturvedi Nish , HUGHES Alun D.
Published: January 2009

Diabetes aggravates the impact of elevated BP (blood pressure) on the microcirculation, and people of African ancestry with diabetes are more susceptible to microvascular damage than Europeans. In the present study, we investigated possible differences in the retinal microcirculation in people of European and African-Caribbean ethnicity with diabetes that might account for this. A total of 51 subjects with Type 2 diabetes (age 40–65 years; 25 male; 29 African-Caribbean) were studied. Clinic and 24 h ambulatory BP, and fasting glucose, insulin and lipids were measured. Digital retinal images were analysed using custom-written semi-automatic software to determine: LDR (length/diameter ratio) and AVR (arteriolar/venular diameter ratio), branching angles, vessel tortuosity and NT (number of terminal vessel branches). Arterioles were narrower in European people with diabetes than in African-Caribbean people with diabetes [mean (S.D.) arteriolar diameter, 76 (7) compared with 82 (11) μm respectively (P=0.03); arteriolar LDR, 28.1 (8.5) compared with 23.7 (7.0) respectively (P=0.046); and AVR, 0.66 (0.21) compared with 0.90 (0.36) respectively (P=0.028)]. Ethnic differences in arteriolar LDR, arteriolar diameter and AVR were not explained by differences in BP, but were attenuated by adjustment for the duration of diabetes. There was no significant relationship between BP and arteriolar narrowing in the group as a whole, although the relationship between arteriolar LDR and systolic BP was stronger in Europeans than African-Caribbeans [β=0.08 (0.07) compared with β=0.03 (0.06); P=0.03]. In conclusion, in the presence of diabetes, a relationship between BP and retinal arteriolar diameter was not evident and implies impaired small artery remodelling in the presence of diabetes. African-Caribbean people with diabetes have wider retinal arterioles and this could contribute to enhanced microvascular damage in this ethnic group.
Nonlinear acoustic waves in nonthermal plasmas with negative and positive dust
Authors: Verheest Frank
Published: January 2009

Using a Sagdeev pseudopotential formalism where nonlinear structures are stationary in a co-moving frame, large dust-acoustic solitary waves and double layers have been studied in plasmas with negative and positive cold dust, in the presence of nonthermal electrons and ions. This has been done in a systematic way, to delimit the compositional parameter space in which such modes can be found. The existence domain of negative/positive solitary waves is limited by infinite compression of the negative/positive dust or by the occurrence of negative/positive double layers. These double layers require a sufficient nonthermality of the electrons/ions and the presence of enough positive/negative dust. There are parameter ranges where both negative and positive solitary structures coexist, sometimes both of the solitary wave type, sometimes one a solitary wave and the other a double layer. Typical Sagdeev pseudopotentials and solitary wave profiles have been presented.
Propagating high-frequency shear waves in simple fluids
Authors: Colosqui Carlos , Chen Hudong , Shan Xiaowen , Staroselsky I. , Yakhot Victor
Published: January 2009

A complex dynamics of a shear wave decay, defined as an initial value problem u(y,0)=U sin(ky)i, where i is a unit vector in the x-direction, is investigated in the entire range of the Weissenberg–Knudsen number (Wi=τνk2=τ2c2k2) variation 0≤Wi≤∞, where τ and c are the fluid relaxation time and speed of sound in the vicinity of thermodynamic equilibrium, respectively. It is shown that in the limit Wi⪡1, the shear wave decay is a purely viscous process obeying a parabolic diffusion equation. When Wi⪢1, a completely new regime emerges, the flow behaves as a dissipative transverse traveling wave. This transition is theoretically predicted as a solution to the Boltzmann–Bhatnagar–Gross–Krook equation and confirmed by the lattice Boltzmann numerical simulations. In the limit Wi=τνk2⪢1 the observed slowing down of the shear wave decay can be interpreted as a high-frequency drag reduction.
Cellular vortex shedding in the wake of a tapered plate at low Reynolds number
Authors: Khaledi Hatef A. , Narasimhamurthy Vagesh D. , Andersson Helge I.
Published: January 2009

The unsteady near wake behind a linearly tapered plate has been investigated numerically. The tapering made the Reynolds number based on the inflow velocity and the local width of the plate vary from 25 to 100. The wake flow comprised three different flow regimes coexisting side by side. The wake flow was steady behind the narrow end of the plate. Periodic vortex shedding occurred downstream from where the local Reynolds number exceeded 32. Vortex dislocations enabled a cellular shedding pattern with shedding frequency decreasing toward the wide end of the plate. The regular oblique vortex shedding near midspan was subjected to three-dimensional scrambling toward the wide end of the plate which gave rise to streamwise-oriented vortex structures. The Strouhal number was distinctly lower than in the wake of a uniform plate whereas the base pressure coefficient was substantially higher.
All-organic solution-processed two-terminal transistors fabricated using the photoinduced p-channels
Authors: Chung Dae Sung , Yun Won Min , Nam Sooji , Kim Se Hyun , Park Chan Eon , Won Park Jong , Kwon Soon-Ki , Kim Yun-Hi
Published: January 2009

All-organic solution-processed two-terminal transistors were fabricated by replacing the “field-induced p-channel” of an organic field-effect transistor with a “photoinduced p-channel.” A simple device structure—containing solution-processed 2,6-di(naphthalene-2-yl)-9,10-bis(triisopropylsilylethynyl)anthracene single crystals as the active layer (on a plastic substrate) and poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) as source and drain electrodes—enabled high-performance photosensor (and even transistor) behavior, showing pseudo-output and transfer curves with an on/off ratio of 5×102. We explain this photogenerated p-channel effect using Helfrich’s theory, which describes the photodetrapping behavior of a space-charge-limited current under illumination.
An expression for the temperature gradient in chaotic fields
Authors: Hudson S. R.
Published: January 2009

A coordinate system adapted to the invariant structures of chaotic magnetic fields is constructed. The coordinates are based on a set of ghost-surfaces, defined via an action-gradient flow between the minimax and minimizing periodic orbits. The construction of the chaotic coordinates allows an expression describing the temperature gradient across a chaotic magnetic field to be derived. The results are in close agreement with a numerical calculation.
Probing subglass relaxation in polymers via a geometric representation of probabilities, observables, and relaxation modes for discrete stochastic systems
Authors: Boulougouris Georgios C. , Theodorou Doros N.
Published: January 2009

The dynamics of many physical, chemical, and biological systems can be reduced to a succession of infrequent transitions in a network of discrete states representing low energy regions in configuration space. This enables accessing long-time dynamics and predicting macroscopic properties. Here we develop a new, perfectly general statistical mechanical/geometric formulation that expresses both state probabilities and all observables in the same Euclidean space, spanned by the eigenvectors of the symmetrized time evolution operator. Our formalism leads to simple expressions for nonequilibrium and equilibrium ensemble averages, variances, and time correlation functions of any observable and allows a rigorous decomposition of the dynamics into relaxation modes. Applying it to subglass segmental relaxation in atactic polystyrene up to times on the order of 10 μs, we probe the molecular mechanism of the γ and δ processes and unequivocally identify the δ process with rotation of a single phenyl group around its stem.
The rheology of hard sphere suspensions at arbitrary volume fractions: An improved differential viscosity model
Authors: Mendoza Carlos I. , Santamaría-Holek I.
Published: January 2009

We propose a simple and general model accounting for the dependence of the viscosity of a hard sphere suspension at arbitrary volume fractions. The model constitutes a continuum-medium description based on a recursive-differential method where correlations between the spheres are introduced through an effective volume fraction. In contrast to other differential methods, the introduction of the effective volume fraction as the integration variable implicitly considers interactions between the spheres of the same recursive stage. The final expression for the viscosity scales with this effective volume fraction, which allows constructing a master curve that contains all the experimental situations considered. The agreement of our expression for the viscosity with experiments at low- and high-shear rates and in the high-frequency limit is remarkable for all volume fractions.
Stability of the plane shear flow of dilute polymeric solutions
Authors: Chokshi Paresh , Kumaran V.
Published: January 2009

Three variants of Oldroyd-B model are analyzed for stability of the base profile in plane Couette flow of dilute polymeric fluid at moderate Reynolds number. The stability to two-dimensional disturbances is analyzed for the linearized problem as well as the weakly nonlinear flow. We begin with the classical Oldroyd-B model with emphasis on the disturbances with axial wavenumber α∼Re1/2, where Re is the Reynolds number based on maximum velocity and channel width. For linearly stable flow, the finite amplitude stability is analyzed using the equilibrium flow method, wherein the nonlinear flow is assumed to be at the transition point. For the classical Oldroyd-B fluid, the threshold kinetic energy for the equilibrium wall mode disturbances is found to be higher for the viscoelastic fluid than for the Newtonian fluid. In the second variant, the Oldroyd-B model with additional artificial diffusivity is studied. In this model, the diffusion modes, not present in the classical Oldroyd-B model, are introduced. For large wavenumber disturbances, the diffusion modes become the slowest decaying modes in comparison to the wall modes. The threshold energy for the diffusive Oldroyd-B model is smaller than that for the Newtonian fluid. The third variant of the Oldroyd-B model accounts for the nonhomogeneous polymer concentration coupled with the polymeric stress field. While the base profile is linearly stable for the first two models, the nonhomogeneous Oldroyd-B fluid exhibits an instability in the linear analysis. The “concentration mode” becomes unstable when the fluid Weissenberg number exceeds a certain transition value. This mode of instability, driven by the stress-induced fluctuations in polymer number density, renders the uniform polymer concentration profile unstable leading to the well-known phenomenon of flow-induced demixing.
Bonding anisotropy in multiferroic TbMnO3 probed by polarization dependent x-ray absorption spectroscopy
Authors: Chen J. M. , Lee J. M. , Chen C. K. , Chou T. L. , Lu K. T. , Haw S. C. , Liang K. S. , Chen C. T. , Jeng H. T. , Huang S. W. , Yang T. J. , Shen C. C. , Liu R. S. , Lin J. Y. , Hu Z.
Published: January 2009

O K- and Mn L2,3-edges x-ray absorption spectra of orthorhombic TbMnO3 single crystals show strong polarization dependence, in contrast with results of previous experiments on orthorhombic LaMnO3 and DyMnO3 thin films that show nearly isotropic spectral structure. First-principles calculations reveal that TbMnO3 exhibits a zigzag eg orbital ordering ground state. The highly distorted MnO6 octahedron and orbital ordering in TbMnO3 produce highly anisotropic Mn–O bonding within the ab plane, a frustration of the magnetic ordering, and the formation of complicated incommensurate magnetic structures.
Full color control and white emission from conjugated polymer nanofibers
Authors: Camposeo Andrea , Di Benedetto Francesca , Cingolani Roberto , Pisignano Dario
Published: January 2009

The authors demonstrate full color tunability in the visible range, including white emission, by polymer nanofibers based on binary blends of conjugated materials. The nanofibers are realized by electrospinning and their emission is based on the dipole-dipole energy transfer from a blue-emitting donor and a red-emitting acceptor conjugated polymer. The fibers are characterized by scanning electron microscopy and time-resolved and cw photoluminescence. Light emission is tuned from blue to red, including bright white with color coordinates (0.38, 0.34) according to the standard of the Commission Internationale de l’Eclairage. Polymer nanofibers based on blends of conjugated compounds turn out to be a promising class of organic semiconductor building blocks for nanophotonics.
Influence of growth mode on the structural, optical, and electrical properties of In-doped ZnO nanorods
Authors: Jung M. N. , Koo J. E. , Oh S. J. , Lee B. W. , Lee W. J. , Ha S. H. , Cho Y. R. , Chang J. H.
Published: January 2009

The growth mechanism of In-doped ZnO (ZnO:In) nanorods grown on AuGe/Si(111) substrates has been investigated. Unlike to general vapor-liquid-solid mechanism, the adatom kinetics on the surface determines the length-diameter relationship [L(D)], initial nuclei size (D∗), and spatial distribution of impurity atoms. The incorporated In-concentration was estimated to be within solid solubility limit of ZnO in terms of x-ray diffraction analysis, but the evolution of photoluminescence peak position and intensity revealed an evidence of extrinsic carrier increment. Hall-effect measurement was used to evaluate the carrier concentration of ZnO:In nanorods.
Effect of an external electric field on the dissociation energy and the electron density properties: The case of the hydrogen bonded dimer HF⋯HF
Authors: Mata Ignasi , Molins Elies , Alkorta Ibon , Espinosa Enrique
Published: January 2009

The effect of a homogeneous external electric field parallel to the hydrogen bond in the FH⋯FH dimer has been studied by theoretical methods. The quantum theory of atoms in molecules methodology has been used for analyzing the electron distribution of the dimer, calculated with different hydrogen bond distances and external field magnitudes. It is shown that an electric field in the opposite direction to the dipole moment of the system strengthens the interaction due to a larger mutual polarization between both molecules and increases the covalent character of the hydrogen bond, while an external field in the opposite direction has the inverse effect. The properties of the complex at its equilibrium geometry with applied field have been calculated, showing that dependencies between hydrogen bond distance, dissociation energy, and properties derived from the topological analysis of the electron distribution are analogous to those observed in families of XDH⋯AY complexes. The application of an external field appears as a useful tool for studying the effect of the atomic environment on the hydrogen bond interaction. In the case of FH⋯FH, both the kinetic energy density and the curvature of the electron density along the hydrogen bond at the bond critical point present a surprisingly good linear dependence on the dissociation energy. The interaction energy can be modeled by the sum of two exponential terms that depend on both the hydrogen bond distance and the applied electric field. Moreover, as indicated by the resulting interaction energy observed upon application of different external fields, the equilibrium distance varies linearly with the external field, and the dependence of the dissociation energy on either the hydrogen bond distance or the external electric field is demonstrated to be exponential.