bluuebunny/crossref_metadata_2025 huggingface dataset:
LNG vapor cloud exclusion zones for spills into impoundments
Authors: Havens Jerry , Spicer Tom
Published: July 2005

LNG spills on land are most likely to happen in dike/impoundment areas, introducing the need to consider effects of dike/impoundment walls on vapor holdup and dispersion. The DEGADIS and FEM3A models are approved for determination of vapor cloud exclusion zones in 49 CFR 193, but DEGADIS is limited to prediction of dispersion from area sources over flat, obstacle‐free terrain and is therefore not directly applicable to spills in dike/impoundment areas. However, FEM3A, which is a computational fluid dynamics (CFD) model, is directly applicable. Before FEM3A was approved, ad hoc methods were widely used to determine input conditions for DEGADIS to estimate dispersion downwind of a dike system for such releases. Vapor holdup and mixing with air in a dike system have been studied in wind tunnel and field experiments, and the fallacy of using an overly simplistic estimation of the time and rate of vapor cloud overflow has been demonstrated. In some cases, these ad hoc methods have resulted in exclusion zone determinations that do not provide for public safety as intended by 49 CFR 193. This paper summarizes the current state of knowledge about this important vapor dispersion scenario, including key experimental data that address the question. Applications of FEM3A to determine exclusion zones for a hypothetical spill within a typical dike/tank configuration, as well as a shortcut use of FEM3A to describe vapor overflow from the same impoundment for use as input information for DEGADIS simulation of the dispersion downwind from the dike, are illustrated. © 2005 American Institute of Chemical Engineers Process Saf Prog, 2005
Dehydration‐regulated processing of late embryogenesis abundant protein in a desiccation‐tolerant nematode
Authors: Goyal Kshamata , Pinelli Claudia , Maslen Sarah L. , Rastogi Rakesh K. , Stephens Elaine , Tunnacliffe Alan
Published: July 2005

Late embryogenesis abundant (LEA) proteins occur in desiccation‐tolerant organisms, including the nematodeAphelenchus avenae, and are thought to protect other proteins from aggregation. Surprisingly, expression of the LEA protein AavLEA1 inA. avenaeis partially discordant with that of its gene: protein is present in hydrated animals despite low cognate mRNA levels. Moreover, on desiccation, when its gene is upregulated, AavLEA1 is specifically cleaved to discrete, smaller polypeptides. A processing activity was found in protein extracts of dehydrated, but not hydrated, nematodes, and main cleavage sites were mapped to 11‐mer repeated motifs in the AavLEA1 sequence. Processed polypeptides retain function as protein anti‐aggregants and we hypothesise that the expression pattern and cleavage of LEA protein allow rapid, maximal availability of active molecules to the dehydrating animal.
Arabidopsis thaliana MTP1 is a Zn transporter in the vacuolar membrane which mediates Zn detoxification and drives leaf Zn accumulation
Authors: Desbrosses-Fonrouge Anne-Garlonn , Voigt Katrin , Schröder Astrid , Arrivault Stéphanie , Thomine Sébastien , Krämer Ute
Published: July 2005

The Arabidopsis thaliana metal tolerance protein 1 (MTP1) of the cation diffusion facilitator family of membrane transport proteins can mediate the detoxification of Zn in Arabidopsis and yeast. Xenopus laevis oocytes expressing AtMTP1 accumulate more Zn than oocytes expressing the AtMTP1D94A mutant or water‐injected oocytes. An AtMTP1‐GFP fusion protein localizes to the vacuolar membrane in root and leaf cells. The analysis of Arabidopsis transformed with a promoter‐GUS construct suggests that AtMTP1 is not produced throughout the plant, but primarily in the subpopulation of dividing, differentiating and expanding cells. RNA interference‐mediated silencing of AtMTP1 causes Zn hypersensitivity and a reduction in Zn concentrations in vegetative plant tissues.
HER2 signaling downregulation by trastuzumab and suppression of the PI3K/Akt pathway: An unexpected effect on TRAIL‐induced apoptosis
Authors: Dubská Lenka , Anděra Ladislav , Sheard Michael Allen
Published: July 2005

We investigated whether HER2 downregulation by trastuzumab modulates the responsiveness of breast cancer cells to TNF‐related apoptosis‐inducing ligand (TRAIL). Interestingly, in contrast to increased response to TRAIL in SKBr3 cells, trastuzumab decreased the susceptibility of BT474 cells to TRAIL. This decrease was also observed after exogenous inhibition of PI3‐K/Akt kinase, but not MAPK/ERK kinase (MEK)/mitogen‐activated protein kinase (MAPK). In BT474 cells, but not SKBr3 cells, inhibition of the HER2/phosphatidylinositol 3′ kinase (PI3K)/Akt pathway resulted in downregulation of the pro‐apoptotic receptors TRAIL‐receptor 1 (TRAIL‐R1) and TRAIL‐R2. TRAIL‐induced caspase‐8 activation, Bid processing, drop of ΔΨ
m, and poly ADP‐ribose polymerase (PARP) cleavage but not in caspase‐9 activation, and these events were inhibited in HER2/PI3K/Akt‐suppressed BT474 cells, which on the other hand exhibited downregulation of Bcl‐xL and increased response to mitomycin C. We show that HER2/PI3K/Akt pathway may play a specific pro‐apoptotic role in certain cell type by inducing TRAIL‐R1 and ‐R2 expression and thereby enhancing responsiveness to TRAIL.
PUBLIC AUTHORITIES AS “VICTIMS” UNDER THE HUMAN RIGHTS ACT
Authors: Davis Howard
Published: July 2005

ONE feature of the current debate concerning the term “public authority” in the Human Rights Act 1998 is a rule to the effect that public authorities are not themselves capable of having and enforcing Convention rights. In what follows this will be referred to as the “rights-restriction rule”. The position was confirmed by the House of Lords in Aston Cantlow and has been given effect by the courts in relation to English local authorities and to NHS Trusts in Scotland. Despite this, doubts have been expressed. In particular the parliamentary Joint Committee has suggested, though without argument, that the denial of Convention rights to public authorities may be wrong in principle and that there are “circumstances in which public authorities have Convention rights”.
INTERPRETING THE DISABILITY GROUND OF THE ABORTION ACT
Authors: Scott Rosamund
Published: July 2005

“NOT only would it be a bold and brave judge … who would seek to interfere with the discretion of doctors acting under the Abortion Act 1967, but I think he would really be a foolish judge who would try to do any such thing, unless, possibly, where there is clear bad faith and an obvious attempt to perpetrate a criminal offence.” So said Sir George Baker P. in Paton v. B.P.A.S. and his view has been repeated at apposite judicial moments in subsequent cases. Recently, however, a legal attempt was indeed made to question the discretion of doctors in Jepson v. The Chief Constable of West Mercia Police Constabulary. Reverend Joanna Jepson asked the West Mercia Police to investigate doctors who had authorised an abortion for bilateral cleft lip and palate at 28 weeks under the disability ground of the Abortion Act 1967 (as amended by the Human Fertilisation and Embryology Act 1990). Abortion is legal under that section if two doctors have formed an opinion in good faith that “there is a substantial risk that if the child were born it would suffer from such physical or mental abnormalities as to be seriously handicapped”.
AN EMPIRE OF LIGHT? LEARNING AND LAWMAKING IN THE HISTORY OF GERMAN LAW
Authors: Vogenauer Stefan
Published: July 2005

JOHN Austin, having spent the winter term of 1827/28 in the idyllic and peaceful Rhenanian university town of Bonn, far away from the bustle of London and the irritating failures he had suffered at the chancery bar, was unrivalled in his admiration for the modern version of Roman law as it had been interpreted, refined and further developed by the German scholars of his time. It was, he exclaimed, “greatly and palpably superior, considered as a whole, to the law of England. Turning from the study of the English to the study of the Roman law, you escape from the empire of chaos and darkness, to a world that seems by comparison, the region of order and light”. How he longed to be as acknowledged and as influential as one of the great expositors of that law. “I was born out of time and place”, he is reported to have lamented, “I ought to have been a schoolman of the twelfth century—or a German professor”. His desire was rather understandable, given that the nineteenth century English law professors regarded themselves as “a feeble folk.
Cross-stress tolerance and expression of stress-related proteins in osmotically desiccated entomopathogenicSteinernema feltiaeIS-6
Authors: CHEN S. , GOLLOP N. , GLAZER I.
Published: July 2005

Infective juveniles (IJs) of the entomopathogenic nematode (EPN)Steinernema feltiaeIS-6 can survive exposure to 24% glycerol solution by entering an osmotically desiccated state. Exposure of osmotically desiccated nematodes to extreme temperature assays (40 °C for 10 h and −20 °C for 360 h) resulted in gradual reduction in survival, whereas non-desiccated IJs died within a short exposure to the assay conditions. Through SDS-PAGE, a stress-related protein UNC-87 was found in osmotically desiccated IJs exposed to 40 °C for 3, 6, and 8 h, whose survival rates were 98·9±1·43, 78·5±5·87 and 20·9±4·93%, respectively. The protein was not found in IJs following exposure of osmotically desiccated individuals to 40 °C for 10 h, in which none of the IJs survived. After exposure to −20 °C for 360 h, the survival of osmotically desiccated EPNs with a weak band of UNC-87 was 13·0±3·32%. To identify other responsive proteins that are required for osmotic stress, we used 2-dimensional electrophoresis to analyse the proteins in osmotically desiccated EPNs. The results revealed that 10 novel protein spots and 10 up-regulated protein spots in osmotically desiccated IJs were detected by digital image analysis. Mass spectrometry analysis of 7 significant spots indicated that osmotic stress in desiccated IJs was associated with the induction of actin, Proteasome regulatory particle (ATPase-like), GroEL chaperonin, GroES co-chaperonin and transposase family member. It seems to show actin, UNC-87 and Proteasome regulatory particle may play distinct roles in specific aspects of organization of macromolecular structures under desiccation stress. GroEL and GroES are members of the Hsp60 family of chaperons.
On the Proletarian Identity of “A Woman Dressed as an Enormous Beetle”
Authors: Ngai Mae M.
Published: July 2005

A set of politics that uses rhetoric, imagery, music, and performance to promote interests that are distinctively and explicitly identified with the working class, Burgmann productively suggests, might revitalize the labor movement. Yet the effort to apply lessons from “identity politics” to “class politics” reproduces two problems in contemporary radicalism. First, by reducing the movements of ethno-racial minorities, women, and gays and lesbians to “identity politics” Burgmann underestimates those movements' claims to civil rights, human rights, socioeconomic improvement, and their general democratic nature. Second, the use of “class” to explain the antiglobalization movement is anachronistic and inadequate to the task of understanding radical politics today.
Moralizing Doesn't Help
Authors: Gordon Linda
Published: July 2005

Verity Burgmann's condemnation of identity politics is unhelpful, because it is moralistic and ahistorical. Its assumptions take us back to a time before the civil rights, New Left, women's, and gay movements reinvented the Left so as to articulate their aspirations and grievances.
Terror and Violence: The Dark Face of Spanish Anarchism
Authors: Casanova Julián
Published: July 2005

This article focuses on the various examples of anarchist violence, from terrorist action in the 1890s to anonymous bombs of the first decade of the twentieth century; from the tyranny of the Star pistol in the 1920s to the uprisings and revolutionary terror of the Second Republic and the Civil War. What follows is a story that is contradictory, heroic, and menacing.
The Myth of the Peaceable Peasant in Northern Spain: Asturias 1898–1914
Authors: Uría Jorge
Published: July 2005

The picture has prevailed in Spanish social history of a revolutionary, insurrectional peasantry in the south of the country. Aided by literary or artistic analyses, this article shows the existence, in the Spanish north during the transition from the nineteenth to the twentieth century, of a counter-model consisting of small landowners. This model was based on real facts, such as the permanence of small and medium land properties, the preservation of the commons, and the stability of leaseholds, all of which contributed to its literary idealization.

However, a more profound and detailed analysis uncovers the existence of other types of conflicts which are different from the large unionized demonstrations of the Andalusian south. In fact, conflict arose in the north with respect to leaseholds and surpluses of milk, cider, or sugar beet. Old emblems of peaceful peasant life such as popular festivities were tainted with criminality, as well as with “urban” and “industrial” delinquency and the old systems of communal solidarity were redefined, which forced political bargaining in local and municipal life.
The End of Indenture? Asian workers in the Australian Pearling Industry, 1901–1972
Authors: Martínez Julia
Published: July 2005

The historical circumstances which led to the end of the indentured labor trade suggest that its abolition was only partially the result of humanitarian concern for the welfare of workers. It was the development of nationalism, both in sending and receiving countries, that prompted a rethinking of the racialized labor organization of indenture. In Australia, the introduction of the White Australia policy in 1901, with its restrictions on non-white immigration and employment, is usually thought to coincide with the abolition of the indentured labor trade. But the Australian pearl-shelling industry continued to employ indentured Asian workers up until the 1970s. This case study extends the historical analysis of indenture well beyond its supposed international abolition. In doing so, it demonstrates a degree of continuity of colonial thought and practice which persisted in the face of global decolonization.
Wendell Pritchett,Brownsville, Brooklyn: Blacks, Jews, and the Changing Face of the Ghetto. Chicago: University of Chicago Press, 2002. xii + 333 pp. $35 cloth; $20 paper.
Authors: Fure-Slocum Eric
Published: July 2005

Wendell Pritchett challenges popular and scholarly images of the modern ghetto by highlighting Brownsville's history as a working-class neighborhood. This area of East Brooklyn underwent significant racial change, beginning the twentieth century as a largely white, Jewish neighborhood. Brownsville's black and Latino populations grew rapidly in the postwar years. Between 1940 and 1970, the population switched from eighty-five percent white to ninety-five percent black and Latino. Throughout these decades, however, this remained a home for New York's changing working classes. Brownsville residents, generally from the lower tiers of the city's working class, shared a history of political and economic marginalization. The neighborhood's later residents faced greater obstacles, as a result of racism, public policy, and economic change. Pritchett's fine study chronicles these changes and continuities and emphasizes white and black residents' unending efforts to secure needed resources and power.
An estimation of annual new production and carbon fluxes in the northeast Atlantic Ocean during 2001
Authors: Fernández I. Camila , Raimbault Patrick , Garcia Nicole , Rimmelin Peggy , Caniaux Guy
Published: July 2005

A dual 13C/15N isotopic technique was used to estimate carbon and nitrogen uptake rates during the 1‐year‐long Programme Océan Multidisciplinaire Méso Echelle (POMME) experiment in the northeast basin of the Atlantic Ocean (16°–22°W, 38°–45°N). Rates of primary production ranged from 2.26 μmoles L−1 d−1 in winter to maximum surface values of 7.8 μmoles L−1 d−1 during the spring season. Nitrate assimilation was intense since the beginning of winter and accounted for 3–7 mmoles m−2 d−1 in the first 80 m depth of the water column. Rates increased to 5–9 mmoles m−2 d−1 during the spring season. NO3− uptake rates during the late summer season were close to winter values. Ammonium assimilation activity balanced the uptake of nitrate for all seasons. The seasonal f ratio was close to 0.28 in winter, increased to 0.34 in spring, and, finally, decreased to 0.25 in late summer. Annual carbon uptake rates for the entire POMME area accounted for 16.9 moles C m−2 yr−1. From this result, annual new production could be estimated to 5.7 moles C m−2 yr−1.
Regional contrasts in dust emission responses to climate
Authors: Zender Charles S. , Kwon Eun Young
Published: July 2005

Time‐series analysis of Earth's major dust source regions reveals common traits in responses of wind erosion to climate anomalies. Lag cross‐correlations of monthly mean aerosol optical depth, precipitation, vegetation, and wind speed are examined from 1979–1993. The response to monthly climate anomalies can differ greatly from the response to seasonal mean climate. The signs, magnitudes, and lags of highly significant (p < 0.01) correlations show that 14 important mineral dust source areas characterized by Prospero et al. (2002) fall into four response categories. Each category represents distinct mechanisms by which climate anomalies influence subsequent atmospheric dust loading on seasonal to interannual timescales. In most regions, precipitation and vegetation together strongly constrain dust anomalies on multiple timescales. In these regions, dry anomalies increase, and wet anomalies reduce, dust emission. Interestingly, in many other regions the contrary is true: Dust and precipitation anomalies correlate positively, consistent with sediment‐supply factors. The response timescales are consistent with loss of surface crusts (less than 1 month) and with alluvial transport and dessication (interannual lags). Supply‐limited dust emission appears more prevalent than previously thought and is not accounted for in models. Reproducing these wind erodibility responses in models may help remediate underprediction of observed seasonal to interannual dust variability.
Snow‐fed streamflow timing at different basin scales: Case study of the Tuolumne River above Hetch Hetchy, Yosemite, California
Authors: Lundquist Jessica D. , Dettinger Michael D. , Cayan Daniel R.
Published: July 2005

Diurnal cycles in snow‐fed streams provide a useful technique for measuring the time it takes water to travel from the top of the snowpack, where snowmelt typically peaks in the afternoon, to the river gauge, where the daily maximum flows may arrive many hours later. Hourly stage measurements in nested subbasins (6‐775 km2) of the Tuolumne River in Yosemite National Park illustrate travel time delays at different basin scales during the spring 2002 and 2003 melt seasons. Travel times increase with longer percolation times through deeper snowpacks, increase with longer travel times over land and along longer stream channels, and increase with slower in‐stream flow velocities. In basins smaller than 30 km2, travel times through the snowpack dominate streamflow timing. In particular, daily peak flows shift to earlier in the day as snowpacks thin and mean discharges increase. In basins larger than 200 km2, snowpack heterogeneity causes the hour of peak flow to be highly consistent, with little or no variation as the snowpack thins. Basins with areas in between 30 and 200 km2 exhibit different sequences of diurnal streamflow timing in different years, sometimes acting like small basins and other times like large basins. From the start of the melt season until the day of peak snowmelt discharge, increasing travel distances in channels as the snow line retreats to higher elevations do not cause long enough travel delays to offset the observed decrease in mean travel times through the snowpack. A model that couples porous medium flow through thinning snowpacks with free surface flow in stream channels can reproduce the observed patterns, provided that the model incorporates snowpack heterogeneity.
The Saturnian plasma sheet as revealed by energetic particle measurements
Authors: Krupp N. , Lagg A. , Woch J. , Krimigis S. M. , Livi S. , Mitchell D. G. , Roelof E. C. , Paranicas C. , Mauk B. H. , Hamilton D. C. , Armstrong T. P. , Dougherty M. K.
Published: July 2005

Since July 2004 Cassini is in orbit around Saturn providing in‐situ measurements of the Saturnian magnetosphere. One of the three sensors of the Magnetospheric Imaging Instrument (MIMI) is the Low Energy Magnetospheric Measurement System (LEMMS) that responds to energetic particles which can serve as indicators of key regions (Krimigis et al., 2005) and ongoing plasma processes in the magnetosphere. In this paper we identify and characterize, based on energetic particle and magnetic field measurements, the radiation belts, the plasma sheet, and the lobe region. The transition between plasma sheet and lobe region sometimes occurs very rapidly, and sometimes occurs with the period of Saturn's rotation. We explain the highly variable nature of the Saturnian plasma sheet as a combination of the geometry of the Cassini trajectory, together with the variable location of the boundary between open and closed field lines caused by a strong localized magnetic anomaly in the Saturnian field.
A drop in mid‐summer shortwave radiation induced by changes in the ice‐surface condition in the central Arctic
Authors: Inoue Jun , Kikuchi Takashi , Perovich Donald K. , Morison James H.
Published: July 2005

Ice‐surface changes during summer and effects on solar heat input in the Arctic were analyzed using incoming shortwave radiation data from drifting buoys deployed in 2002, 2003, and 2004 as part of the North Pole Environmental Observatory project. Observed shortwave radiation was about half of the incoming shortwave radiation at the top of the atmosphere during early summer, suggesting cloudy skies. In each year, events occurred after mid‐summer during which time the shortwave radiation decreased 33% to one third of shortwave radiation at the top of the atmosphere. Snow‐depth data, aerial photos, and date of melt onset at the buoy site suggest that a decrease in snow/ice albedo induced by snow melting and melt‐pond formation modified the amount of shortwave radiation through multiple reflections. A simplified calculation of the ice‐albedo feedback revealed that the drop in shortwave radiation after mid‐summer was self damping.
Mechanisms of Right Atrial Tachycardia Occurring Late After Surgical Closure of Atrial Septal Defects
Authors: MAGNIN‐POULL ISABELLE , De CHILLOU CHRISTIAN , MILJOEN HIELKO , ANDRONACHE MARIUS , ALIOT ETIENNE
Published: July 2005

Introduction: In patients without structural heart disease, the most frequently occurring AT is the common atrial flutter. In patients with repaired congenital heart disease other mechanisms of AT may occur, due to the presence of an atriotomy that can provide a substrate for reentry. The aim of the present study was to identify the mechanisms of atrial tachycardia (AT) occurring late after atrial septum defect (ASD) repair, with the help of a three‐dimensional electroanatomical mapping system.

Methods and Results: Twenty‐two consecutive patients presenting with AT underwent complete electroanatomic mapping (CARTO®, Biosense Webster, Diamond Bar, CA) of spontaneously occurring and inducible right ATs. Complete maps of 26 ATs were obtained. Three tachycardia mechanisms were identified: single‐loop macroreentrant atrial tachycardia (MAT) (n = 7), double‐loop MAT (n = 18), and focal AT (n = 1). In all MATs, protected isthmuses were identified as the electrophysiological substrate of the arrhythmia, most frequently the cavotricuspid isthmus (CTI) (n = 24), and a gap between the inferior vena cava and a line of double potentials (n = 11). A mean number of 13.5 ± 2.1 radiofrequency applications were delivered to transect these critical parts of the circuit. During a follow‐up of 25 ± 16 months the RF ablation was acutely successful in all patients. Thirteen patients (59%) had an early recurrence of MAT and needed an additional ablation procedure. One of those patients needed two additional ablation procedures.

Conclusions: Three‐dimensional electroanatomic mapping is useful to identify postsurgical AT mechanisms; the CTI isthmus is involved in 92% MAT, and if the right atrial free wall (RAFW) abnormal tissue related to surgical scar is present this substrate contributes to the MAT circuit
Catheter Ablation of Recipient Right Ventricular Tachycardia after Heterotopic Heart Transplantation
Authors: NAKAO MOTOHIRO , RICARD PHILIPPE , DOR VINCENT , SAOUDI NADIR
Published: July 2005

A case is reported of ventricular tachycardia (VT) in a 62‐year‐old male after heterotopic heart transplantation, who occasionally had attacks of palpitation. Surface electrocardiogram suggested VT arising from the recipient heart. Intracardiac electrograms and entrainment mapping confirmed macroreentrant VT located in the recipient right ventricle. Radiofrequency ablation using an electroanatomical mapping system (CARTO™, Biosense Webster, Diamond Bar, CA, USA) successfully eliminated VT.
Increased Extracellular Collagen Matrix in Myocardial Sleeves of Pulmonary Veins: An Additional Mechanism Facilitating Repetitive Rapid Activities in Chronic Pacing‐Induced Sustained Atrial Fibrillation
Authors: CHIU YUNG‐TSUNG , WU TSU‐JUEY , WEI HAO‐JI , CHENG CHING‐CHANG , LIN NAI‐NU , CHEN YING‐TSUNG , TING CHIH‐TAI
Published: July 2005

Introduction: Cell uncoupling due to fibrosis or increased extracellular collagen matrix (ECM) affects the formation of ectopic focal activity. Whether or not the increase of ECM also exists in the pulmonary veins (PVs) with rapid atrial pacing is unknown. We sought to test the hypothesis that in chronic atrial pacing dogs with sustained atrial fibrillation (AF), the amount of ECM was increased in both atria and the PVs.

Methods and Results: We induced sustained AF in dogs by rapid atrial pacing. Computerized mapping techniques were used to map both atria and the PVs. We also used histological assessment to quantify the amount of ECM. After 118 ± 24 days of rapid atrial pacing, sustained AF was induced in 7 dogs. Repetitive rapid activities (RRAs) either continuously or intermittently arose from the PVs during sustained AF. Histological study shows that there was no fibrosis in both atrial free walls and the PVs. However, the amount of ECM was increased in these regions. The mean ECM surface area fraction at each region in the dogs with sustained AF was all significantly higher compared to the corresponding region in normal dogs. Similarly, the heterogeneity of the ECM surface area fraction at each region in the dogs with sustained AF was also all significantly higher compared to normal dogs.

Conclusions: In chronic atrial pacing‐induced sustained AF, structural remodeling (i.e., inhomogeneous increase of ECM) also involves the PVs. Reduced coupling of the myocytes in the PV due to histological changes may provide an additional mechanism facilitating RRAs.
Whistleron gas in magnetized plasmas
Authors: De Martino Salvatore , Falanga Mariarosaria , Tzenov Stephan I.
Published: July 2005

The nonlinear dynamics of whistler waves in magnetized plasmas is studied. Since the plasmas and beam-plasma systems considered here are assumed to be weakly collisional, the point of reference for the analysis performed in the present paper is the system of hydrodynamic and field equations. The renormalization group method is applied to obtain dynamical equations for the slowly varying amplitudes of whistler waves. Further, it has been shown that the amplitudes of eigenmodes satisfy an infinite system of coupled nonlinear Schrödinger equations. In this sense, the whistler eigenmodes form a sort of a gas of interacting quasiparticles, while the slowly varying amplitudes can be considered as dynamical variables heralding the relevant information about the system. An important feature of the approach is that whistler waves do not perturb the initial uniform density of plasma electrons. The plasma response to the induced whistler waves consists in velocity redistribution which follows exactly the behavior of the whistlers. In addition, selection rules governing the nonlinear mode coupling have been derived, which represent another interesting peculiarity of the description presented here.
The electronic structure of liquid water within density-functional theory
Authors: Prendergast David , Grossman Jeffrey C. , Galli Giulia
Published: July 2005

In the last decade, computational studies of liquid water have mostly concentrated on ground-state properties. However, recent spectroscopic measurements have been used to infer the structure of water, and the interpretation of optical and x-ray spectra requires accurate theoretical models of excited electronic states, not only of the ground state. To this end, we investigate the electronic properties of water at ambient conditions using ab initio density-functional theory within the generalized gradient approximation (DFT/GGA), focusing on the unoccupied subspace of Kohn–Sham eigenstates. We generate long (250ps) classical trajectories for large supercells, up to 256 molecules, from which uncorrelated configurations of water molecules are extracted for use in DFT/GGA calculations of the electronic structure. We find that the density of occupied states of this molecular liquid is well described with 32-molecule supercells using a single k point (k=0) to approximate integration over the first Brillouin zone. However, the description of the unoccupied electronic density of states (u-EDOS) is sensitive to finite size effects. Small, 32-molecule supercell calculations, using the Γ-point approximation, yield a spuriously isolated state above the Fermi level. Nevertheless, the more accurate u-EDOS of large, 256-molecule supercells may be reproduced using smaller supercells and increased k-point sampling. This indicates that the electronic structure of molecular liquids such as water is relatively insensitive to the long-range disorder in the molecular structure. These results have important implications for efficiently increasing the accuracy of spectral calculations for water and other molecular liquids.
Analysis of the nuclear-electronic orbital method for model hydrogen transfer systems
Authors: Swalina Chet , Pak Michael V. , Hammes-Schiffer Sharon
Published: July 2005

Fundamental issues associated with the application of the nuclear-electronic orbital (NEO) approach to hydrogen transfer systems are addressed. In the NEO approach, specified nuclei are treated quantum mechanically on the same level as the electrons, and mixed nuclear-electronic wavefunctions are calculated with molecular orbital methods. The positions of the nuclear basis function centers are optimized variationally. In the application of the NEO approach to hydrogen transfer systems, the hydrogen nuclei and all electrons are treated quantum mechanically. Within the NEO framework, the transferring hydrogen atom can be represented by two basis function centers to allow delocalization of the proton vibrational wavefunction. In this paper, the NEO approach is applied to the [He-H-He]+ and [He-H-He]++ model systems. Analyses of technical issues pertaining to flexibility of the basis set to describe both single and double well proton potential energy surfaces, linear dependency of the hydrogen basis functions, multiple minima in the basis function center optimization, convergence of the number of hydrogen basis function centers, and basis set superposition error are presented. The accuracy of the NEO approach is tested by comparison to grid calculations for these model systems.
A method for quantifying annihilation rates of bulk point defects at surfaces
Authors: Kwok Charlotte T. M. , Dev Kapil , Braatz Richard D. , Seebauer E. G.
Published: July 2005

Point defects such as vacancies and interstitial atoms serve as primary mediators of solid-state diffusion in many materials. In some cases, the defects encounter surfaces where annihilation can occur. Quantification of annihilation rates presents formidable challenges, since point defect concentrations are typically low and therefore difficult to monitor directly. The present work develops a method for such quantification based upon measurements of diffusional profile spreading of a foreign species, using as an example isotopically labeled silicon implanted into a silicon matrix. Optimal experimental design techniques together with maximum-likelihood estimation indicate that the loss probability for Si interstitials on nitrogen-covered Si(100) lies at 7.1×10−4.
Gyrokinetic simulation of collisionless trapped-electron mode turbulence
Authors: Dannert Tilman , Jenko Frank
Published: July 2005

Some basic properties of collisionless, trapped-electron mode turbulence in tokamaks are investigated by means of massively parallel gyrokinetic Vlasov simulations. In particular, the spatial structure and wave number spectra of various fluctuating plasma quantities are presented and discussed. An analysis of several cross phase relations supports the view that the transport-dominating scales may be interpreted in terms of remnants of linear modes. In a few test cases, zonal flows are artificially suppressed, demonstrating that their influence on the transport level is small. Finally, the dependence of the latter on several plasma parameters is studied.
Effects of Joule heating on the stability of time-modulated electro-osmotic flow
Authors: Chang Min-Hsing , Homsy G. M.
Published: July 2005

Effects of Joule heating and the induced variable viscosity are considered for time-modulated electro-osmotic flow in a two-dimensional microchannel confined between two infinitely parallel plates. Analytical expressions for both temperature and velocity profiles are obtained through asymptotic expansions for thin Debye layers, providing expressions for both the velocity and temperature “slip” outside these layers, and perturbation techniques for small viscosity variation. The amplitude variation of the temperature due to Joule heating is quite significant at low frequency electric fields, and decays gradually with increasing frequency. The induced variable viscosity effect changes the phase angle between velocity and harmonic electric field in comparison with the constant viscosity case, and reduces the shearing in the velocity profile. Results for the electrokinetic stability problem show that Joule heating generally exhibits a stabilizing effect.
Electron spin resonance investigation of oxygen-vacancy-related defects in BaTiO3 thin films
Authors: Laguta V. V. , Slipenyuk A. M. , Bykov I. P. , Glinchuk M. D. , Maglione M. , Michau D. , Rosa J. , Jastrabik L.
Published: July 2005

The Ti3+ center, based on a regular Ti site perturbed by an oxygen vacancy (VO), is identified by electron spin resonance (ESR) in textured BaTiO3 films. The center shows tetragonal symmetry along cubic ⟨100⟩ axes with g-factors: g‖=1.997, g⊥=1.904. The spectrum of this defect disappeared after the film annealing at 700°C in an O2 atmosphere. We describe the observed spectrum as Ti3+–VO couple defects or F+ center, which have never been observed in bulk BaTiO3. ESR is thus a unique tool to identify oxygen-vacancy-related defects, which have a large effect on the performance of ferroelectric films.
Attractive force on like charges in a complex plasma
Authors: Ishihara Osamu , Sato Noriyoshi
Published: July 2005

Electrostatic attractive force between dust particles in a complex plasma with ion flow is studied. It is shown that there is an attractive force between a pair of dust particles along the ion flow as well as perpendicular to the ion flow. The attractive force perpendicular to the flow results from a release of thermodynamic free energy in charged fine particles, while an attractive force associated with the wake potential acts on a pair of dust particles aligned with the ion flow. Recent experimental observation of the sharp boundary of a void in a complex plasma is interpreted as a result of the attractive force.
Diffusion of nitrogen in silicon
Authors: Fujita N. , Jones R. , Goss J. P. , Briddon P. R. , Frauenheim T. , Öberg S.
Published: July 2005

We use local density functional theory to investigate the diffusion of nitrogen dimers in silicon. We investigate several trajectories for the diffusing dimer finding an alternative one whose barrier is 2.69eV and in close agreement with experimental diffusion data carried out at high temperature. We suggest that recent reports of a low barrier of 1.45eV found from studies of dislocation unlocking are to be understood from the interaction of nitrogen dimers with interstitials or vacancies released by the dislocation.
Threshold voltage instability of amorphous silicon thin-film transistors under constant current stress
Authors: Jahinuzzaman Shah M. , Sultana Afrin , Sakariya Kapil , Servati Peyman , Nathan Arokia
Published: July 2005

We investigate the time-dependent shift in the threshold voltage of amorphous silicon thin-film transistor stressed with constant drain current. We observe a nonsaturating power-law time dependence, which is in contrast to the conventional stretched exponential that saturates at prolonged stress time. The result is consistent with the carrier-induced defect creation model and corroborates the nonlinear dependence of the rate of defect creation on the band-tail carrier density.
Photocatalytic Activity of Neodymium Ion Doped TiO2 for 2-Mercaptobenzothiazole Degradation under Visible Light Irradiation
Authors: Li Fang Bai , Li Xiang Zhong , Cheah Kok Wai
Published: July 2005

Environmental Context. Conventional titanium dioxide catalysts can assist oxidation reactions upon ultraviolet light irradiation. Such photocatalysts are used to degrade organic pollutants in water to less harmful inorganic materials. By modifying the catalyst with luminescent lanthanide ions, the pollutant degradation reaction takes place upon visible light illumination. 2-Mercaptobenzothiazole, a poorly biodegradable and malodourous pollutant used both as a corrosion inhibitor and antifungal agent, is shown to be efficiently mineralized to carbon dioxide, water, ammonium, nitrate, and sulfate with this new catalyst.
Abstract. A series of neodymium ion-doped titanium dioxide (Nd3+-TiO2) catalysts were prepared by means of a sol–gel method. The physical and chemical properties of the catalysts were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) N2 sorbtion method, UV-visible diffusive reflective spectroscopy (DRS), and photoluminescence (PL) analyses. The adsorption behaviour and photocatalytic activity of Nd3+-TiO2 under visible light irradiation were evaluated for aqueous 2-mercaptobenzothiazole (MBT) solution. The analytical results of XRD and BET demonstrate that the neodymium ion doping could reduce the crystallite size and increase the specific surface area of TiO2 catalysts. The analytical results of DRS show that Nd3+ doping did not shift the main absorption band edge significantly, but some new absorption peaks attributable to 4f internal electron transition existed in the visible region. It was further confirmed that significant PL emission occurred in the visible range of 350–700 nm, attributable to the electron transfer between Nd3+ and TiO2 owing to introduction of a Nd 4f level. The experimental results of adsorption isotherm tests demonstrate that both the saturated adsorption amount (Γmax) and adsorption equilibrium constant (Ka) of Nd3+-TiO2 catalysts increased significantly with the increased Nd3+ dosage. Furthermore, the Nd3+-TiO2 catalysts demonstrated significant activity towards photocatalytic degradation of MBT in aqueous solution under visible light irradiation, whereas the TiO2 catalyst did not. An optimal dosage of Nd3+ doping was found to be 0.7%. We propose that the introduction of the Nd 4f level plays a crucial role in visible photosensitization and enhancement of the electron–hole separation.
Measuring Marine Iron(III) Complexes by CLE-AdSV
Authors: Town Raewyn M. , van Leeuwen Herman P.
Published: July 2005

Environmental Context. Iron is an essential element for life in the world's oceans, and in some regions its concentration limits the growth of phytoplankton. The amount of iron(iii) which is available to an organism depends on the exact chemical form in which it exists, for example as dissolved ions or associated with organic compounds. There are widespread reports that marine iron(iii) is predominantly bound in extremely strong complexes. We show that such claims might be the result of an artefact of the measurement technique, CLE-AdSV. Ensuing ideas about the iron biogeochemistry in marine systems might require reconsideration as well.
Abstract. Iron(iii) speciation data, as determined by competitive ligand exchange?adsorptive stripping voltammetry (CLE-AdSV), is reconsidered in the light of the kinetic features of the measurement. The very large stability constants reported for iron(iii) in marine ecosystems are shown to be possibly due to an artefact of the technique, arising from the assumption that equilibrium is achieved between all iron(iii) species of relevance. Particular kinetic properties, related to the special nature of hydroxide as a metal complexant, have the consequence that CLE-AdSV measurements of iron(iii) in seawater generally correspond to the hydroxide complexes only. By the same token, dissolved hydroxide complexes are the key components of the bioavailable iron(iii) pool. The analysis presented herein opens opportunities to exploit CLE-AdSV for more rigorous investigation of the links between the speciation and the bioavailability of iron(iii).
Arsenic's Interaction with Humic Acid
Authors: Warwick Peter , Inam Edu , Evans Nick
Published: July 2005

Environmental Context. Arsenic is of significant environmental concern in much of the world because of its contamination of waters, from mining, industry, sewage disposal, and agriculture. The environmental mobility of arsenic is controlled primarily by adsorption onto metal oxides, especially iron. Humic substances (natural organic matter), which are ubiquitous in aquatic and soil environments, may interfere with this adsorption and arsenic mobility may be increased. Thus, even if it is assumed that humic substances sorb arsenic less strongly than hydrous iron oxides, they may, nevertheless, influence arsenic sorption and mobility, particularly when the iron oxide content in the environment is low. Abstract. The environmental mobility of arsenic is primarily controlled by adsorption onto metal oxide surfaces, particularly iron, aluminium, and manganese. Humic acid (HA) may interfere with this adsorption, thereby increasing arsenic mobility. This study has characterized the interaction of arsenic with HA in a system consisting of HA with As(iii), As(v), and dimethylarsinic acid (DMAA). Three sets of batch experiments were performed at varying pH (3–12), ionic strength (0–0.4 mol dm−3), concentration of each arsenic species (0–100 mg dm−3), and HA concentration (0–10 g dm−3). Arsenic species were shown to react with humic acid. The interaction is postulated to involve bridging metals and deprotonated functional groups within the HA. The association is dependent on pH, ionic strength, and arsenic concentration. The extent of the interaction was greater in the pH range 8–10 for As(v) and DMAA, while it extended to pH 12 for As(iii). The strong pH dependency is probably due to the aqueous speciation of arsenic. The logarithmic conditional association constants for the reactions were found to be 1.97 ± 0.02, 1.58 ± 0.07, and 1.50 ± 0.10 for As(v), As(iii), and DMAA respectively. These values indicate the formation of weak complexes with humic acid.
Organic Iron Complexation Is Real, The Theory Is Used Incorrectly. Comment on 'Measuring Marine Iron(III) Complexes by CLE-AdSV'
Authors: van den Berg Constant M. G.
Published: July 2005

Environmental Context. The theoretical basis on which Town and van Leeuwen (Environ. Chem. 2005, 2, 80) dispute current ideas on the speciation of iron in seawater is valid only for the simplified condition of the binding of ionic Fe3+ with an ionic organic ligand. The possibilities of different pathways for complex formation and dissociation involving mixed hydroxide–organic species, or of different redox states, were not considered. The mismatch with experimental reality shows that the simplification is incorrect.
Cytokinin flows from Hordeum vulgare to the hemiparasite Rhinanthus minor and the influence of infection on host and parasite cytokinins relations
Authors: Jiang Fan , Veselova Sveta , Veselov Dima , Kudoyarova Guzel , Jeschke W. Dieter , Hartung Wolfram
Published: July 2005

Using the facultative root hemiparasite Rhinanthus minor L. and Hordeum vulgare L. as a host, the flows, depositions and metabolism of zeatin-type cytokinins [zeatin (Z), zeatin riboside (ZR), zeatin nucleotide (ZN)] within the host, the parasite and between host and parasite have been studied during the period 41–54 d after planting (i.e. ~30–43 d after successful attachment of the parasite to the host). Parasitism decreased the synthesis of Z in the root (by 57%) and decreased xylem flows (by 56%) and metabolism (by 71%) in leaf laminae. However, phloem flows of Z were increased by 3-fold in the host barley. The deposition of Z in the roots of Rhinanthus and the flows in xylem and phloem were increased by 20, 12, 29-fold, respectively, after successfully attaching to the host barley. However, net biosynthesis of Z in Rhinanthus roots decreased by 35% after attachment. This indicates that a large portion (70%) of xylem flow of Z in attached Rhinanthus was extracted from the host. In singly growing Rhinanthus plants, the balance of Z deposition in the shoot was negative (i.e. Z was metabolised and exported back to root in the phloem). Xylem flows and deposition of ZR and ZN showed comparable quantitative changes after attachment. A significant deposition of Z, ZR and ZN was detected in the haustoria of the Rhinanthus / barley association. The possible physiological functions of the large quantities of Z and ZR and ZN derived from the host barley, for the improved leaf development and the stomatal reactions of the parasitising Rhinanthus are discussed.
Arabidopsis AtCNGC10 rescues potassium channel mutants of E. coli, yeast and Arabidopsis and is regulated by calcium/calmodulin and cyclic GMP in E. coli
Authors: Li Xinli , Borsics Tamás , Harrington H. Michael , Christopher David A.
Published: July 2005

We have isolated and characterised AtCNGC10, one of the 20 members of the family of cyclic nucleotide (CN)-gated and calmodulin (CaM)-regulated channels (CNGCs) from Arabidopsis thaliana (L.) Heynh. AtCNGC10 bound CaM in a C-terminal subregion that contains a basic amphiphillic structure characteristic of CaM-binding proteins and that also overlaps with the predicted CN-binding domain. AtCNGC10 is insensitive to the broad-range K+ channel blocker, tetraethylammonium, and lacks a typical K+-signature motif. However, AtCNGC10 complemented K+ channel uptake mutants of Escherichia coli (LB650), yeast (Saccharomyces cerevisiae CY162) and Arabidopsis (akt1-1). Sense 35S-AtCNGC10 transformed into the Arabidopsis akt1-1 mutant, grew 1.7-fold better on K+-limited medium relative to the vector control. Coexpression of CaM and AtCNGC10 in E. coli showed that Ca2+ / CaM inhibited cell growth by 40%, while cGMP reversed the inhibition by Ca2+ / CaM, in a AtCNGC10-dependent manner. AtCNGC10 did not confer tolerance to Cs+ in E. coli, however, it confers tolerance to toxic levels of Na+ and Cs+ in the yeast K+ uptake mutant grown on low K+ medium. Antisense AtCNGC10 plants had 50% less potassium than wild type Columbia. Taken together, the studies from three evolutionarily diverse species demonstrated a role for the CaM-binding channel, AtCNGC10, in mediating the uptake of K+ in plants.