bluuebunny/crossref_metadata_2025 huggingface dataset:
NT‐proBNP correlates with right heart haemodynamic parameters and volumes in patients with atrial septal defects
Authors: Schoen S.P. , Zimmermann T. , Kittner T. , Braun M.U. , Fuhrmann J. , Schmeisser A. , Strasser R.H.
Published: March 2007

Background:

To investigate the role of N‐terminal pro‐BNP (NT‐proBNP) for the estimation of right heart failure and pulmonary pressure in patients with atrial septal defects (ASD) before and after percutaneous defect closure.

Methods:

We performed correlation analysis for NT‐proBNP and right ventricular systolic pressure (RVSP) as well as right ventricular enddiastolic and endsystolic volume (RVEDV, RVESV) determined by cardiac magnetic resonance imaging (MRI) before and up to one year following ASD closure. Additionally NT‐proBNP concentrations were correlated with right atrial (RA) and RV enddiastolic pressure (RVEDP), ASD size and interatrial left‐to‐right shunt.

Results:

Baseline RVSP was 33±8 mmHg, which decreased significantly during follow‐up. Initially, NT‐proBNP levels were 240±93 pg/ml. After closure, a reduction to 1167±62 pg/ml was obvious (p<0.01). Baseline MRI showed enlarged RV volumes in all individuals. At six and twelve months follow‐up a significant reduction of RVEDV and RVESV was apparent. A positive correlation was noted between RV volumes and NT‐proBNP (r=0.65, p<0.05). Furthermore RA pressure, RVEDP, RVSP and left‐to‐right shunt significantly correlated to peptide levels. No correlation was seen between ASD size and NT‐proBNP.

Conclusion:

NT‐proBNP correlates to right ventricular dilatation, pulmonary pressure and left‐to‐right shunt in volume load of the right heart caused by an underlying ASD.
Structural and biochemical characterization of the Importin‐β · Ran · GTP · RanBD1 complex
Authors: Sarić Marc , Zhao Xiaodong , Körner Carolin , Nowak Christine , Kuhlmann Jürgen , Vetter Ingrid R.
Published: March 2007

Here we present the crystal structure of Importin‐β(1–462) · Ran · GTP · RanBD1ΔN as solved by molecular replacement. HPLC dissociation measurements on this complex show, that the N‐terminus of RanBD may be involved in the release of the hydrolysis‐ and dissociation‐block of Ran by Transportin/Importin‐β. We could identify a pair of amino acids which – upon mutation – weaken the interaction between Ran and Importin‐β specifically to allow dissociation without RanBD. These findings support the hypothesis that a ternary complex of Importin‐β · Ran · GTP · RanBD exists in the final step of the export of Importin‐β from the nucleus and that interaction of the N‐terminus of RanBD with Ran plays a crucial role in disassembly of this complex.
Serum α1-acid glycoprotein (AGP) concentration in non-symptomatic cats with feline coronavirus (FCoV) infection
Authors: Paltrinieri Saverio , Metzger Cecilia , Battilani Mara , Pocacqua Vanessa , Gelain Maria Elena , Giordano Alessia
Published: March 2007

Previous studies have demonstrated that the concentration of α1-acid glycoprotein (AGP) transiently increases in asymptomatic cats infected with feline coronavirus (FCoV). In order to establish whether these fluctuations depend on the FCoV status, the serum concentration of AGP and anti-FCoV antibody titres and/or faecal shedding of FCoVs in clinically healthy cats from catteries with different levels of prevalence of FCoV infection were monitored over time. Serum AGP concentrations fluctuated over time in clinically healthy cats from the cattery with the highest prevalence of feline infectious peritonitis (FIP) and significantly increased just before an outbreak of FIP. Further studies are required to clarify whether the observed increase of AGP concentration is a consequence of the increased viral burden or a protective response against mutated viral strains. Nevertheless, the results of the present study suggest that AGP might be useful in monitoring FCoV–host interactions in FCoV-endemic catteries.
Customization and real time information access in integrated eBusiness supply chain relationships
Authors: Klein Richard
Published: March 2007

eBusiness enabled information systems and technology have proliferated with the diffusion and technological advances of the Internet. This research examines supply chain management relationships between service providers and clients, focusing on the performance impacts of (1) the level of customization implemented by clients using vendor provided eBusiness solutions and (2) the subsequent real time access achieved with respect to operational information maintained by vendors. The study also focuses on the impacts of the provider's information exchange behavior and both parties’ level of trust. Using dyadic data collected from a logistics services provider and 91 clients, findings show that the level of customization and real time information access has a direct positive impact on performance outcomes realized by both. Additionally, results demonstrate that provider's level of trust in the client positively influences their information exchange behavior, and in turn, information exchange behavior positively impacts client customizations.
The role of histone deacetylases (HDACs) in human cancer
Authors: Ropero Santiago , Esteller Manel
Published: March 2007

The balance of histone acetylation and deacetylation is an epigenetic layer with a critical role in the regulation of gene expression. Histone acetylation induced by histone acetyl transferases (HATs) is associated with gene transcription, while histone hypoacetylation induced by histone deacetylase (HDAC) activity is associated with gene silencing. Altered expression and mutations of genes that encode HDACs have been linked to tumor development since they both induce the aberrant transcription of key genes regulating important cellular functions such as cell proliferation, cell‐cycle regulation and apoptosis. Thus, HDACs are among the most promising therapeutic targets for cancer treatment, and they have inspired researchers to study and develop HDAC inhibitors.
A-type leucogranite magmatism in the evolution of continental crust on the western margin of the Siberian craton
Authors: Vernikovskaya A.E. , Vernikovsky V.A. , Sal’nikova E.B. , Kotov A.B. , Kovach V.P. , Travin A.V. , Wingate M.T.D.
Published: March 2007

We discuss problems of the origin, settings, and age of Neoproterozoic A-type leucogranites widespread in the Yenisei Ridge. Combined analysis of geological, petrological, and geochemical (including isotope) data shows that some granitoids (Glushikha complex) were formed at the postcollisional stage (750–720 Ma), and others (Tatarka complex), in an anorogenic environment (680–630 Ma). The anorogenic complex contains diverse igneous rocks, including alkaline varieties and carbonatites. Leucogranites form separate plutons within different igneous complexes. They have high contents of potassium (up to ultrapotassic composition in the Glushikha complex), iron, and fluorine and are depleted in europium. Postcollisional granitoids show the highest concentrations of Rb, Th, and U, extremely low concentrations of Ba and Sr, whereas anorogenic granitoids are rich in Ta, Nb, Y, Sm, and HREE. The obtained data point to the augmented mantle contribution to the formation of continental crust of the Yenisei Ridge between 750 and 630 Ma. We also report new results of U-Pb zircon dating, including SHRIMP and Ar-Ar data.
Neoproterozoic evolution of Rodinia: constraints from new paleomagnetic data on the western margin of the Siberian craton
Authors: Metelkin D.V. , Vernikovsky V.A. , Kazansky A.Yu.
Published: March 2007

The paper summarizes paleomagnetic results obtained from the Neoproterozoic rocks of the western margin of the Siberian craton. On the basis of the obtained paleomagnetic poles and available paleomagnetic data for the Precambrian of Siberia, a new version of the Neoproterozoic segment of the apparent polar wandering path (APWP) is proposed for the craton and is compared with the Laurentian APWP. The superposition of these paths suggests that in the Neoproterozoic the southern margin of the Siberian craton (in modern coordinates) faced the Canadian margin of Laurentia. Most likely, in the end of the Mesoproterozoic and during the Neoproterozoic the Siberian craton and Laurentia were connected to form the supercontinent Rodinia. At 1 Ga the western margin of the Siberian craton was a northern (in modern coordinates) continuation of the western margin of Laurentia. The available paleomagnetic data on Laurentia and continental blocks of Eastern Gondwana (Australia, Antarctica, India, South China) and the proposed APWP trend allowed a new model for the breakup of this segment of Rodinia. Analysis of a total of the data available suggests that strike-slip movements on the background of the progressive opening of the oceanic basin between Siberia and Laurentia were predominant in the south of the Siberian craton during the Neoproterozoic. Similar kinematics is typical of the western margin of Laurentia, where strike-slip motions are probably associated with the progressive opening of the ocean basin between Laurentia and eastern Gondwana.
Northern segment of the Paleoasian Ocean: Neoproterozoic deposition history and geodynamics
Authors: Stanevich A.M. , Mazukabzov A.M. , Postnikov A.A. , Nemerov V.K. , Pisarevsky S.A. , Gladkochub D.P. , Donskaya T.V. , Kornilova T.A.
Published: March 2007

We suggest new age constraints for regional stratigraphic units and a model of the Neoproterozoic geodynamic evolution of the southern Siberian craton proceeding from our data on genesis and lithology of sedimentary and volcanosedimentary complexes and their correlation combined with published geochronological and chemostratigraphic evidence. Large-scale rifting events in the region may have occurred between 1000 and 850 Ma in the east and between 780 and 730 Ma in the west. The latter time span correlates with the breakup of the Rodinia supercontinent. The interval of 780–680 Ma corresponding to the deposition of the Dalnyaya Taiga regional stratigraphic unit was marked by the onset of collision and the development of an island arc and a back-arc basin in the eastern part of the territory. The basal strata of the Baikal and Oselok Groups and their equivalents presumably deposited at about 730 Ma, and their signature of glacial events correlates with the global Sturtian Glacial. The deposition of the Zhuya unit between 680 and 630 Ma was associated with development of a foreland basin which gave way to a system of orogenic foredeeps in the Early Vendian (since 630 Ma). Our studies furnish new data on the stratigraphy of the Baikal Group and shed more light on its complex structure and ambiguously interpreted deposition sequence.
High-pressure complexes of Central Asian Fold Belt: geologic setting, geochemistry, and geodynamic implications
Authors: Volkova N.I. , Sklyarov E.V.
Published: March 2007

Blueschists are constituents of subduction-accretion complexes, where they occur either as separate tectonic slabs, slices, and lenses, or as exotic blocks in a melange. Often associated with ophiolites, blueschists are commonly metamorphosed members of ophiolite sections. Along with ophiolite, a typical component of high-pressure belts is alkaline ocean-island basalt comprehensively studied in the Uimon zone of Gorny Altai and Chara zone of Eastern Kazakhstan. This suggests active plume magmatism in the Early Paleozoic evolution of the Paleoasian Ocean. As inferred from sutures with high-pressure rocks, different parts of Paleoasian Ocean were closing successively.
Dzhida island-arc system in the Paleoasian Ocean: structure and main stages of Vendian-Paleozoic geodynamic evolution
Authors: Gordienko I.V. , Filimonov A.V. , Minina O.R. , Gornova M.A. , Medvedev A.Ya. , Klimuk V.S. , Elbaev A.L. , Tomurtogoo O.
Published: March 2007

We propose a model of the geodynamic evolution of the Dzhida island-arc system of the Paleoasian Ocean margin which records transformation of an oceanic basin into an accretion-collision orogenic belt. The system includes several Vendian-Paleozoic complexes that represent a mature oceanic island arc with an accretionary prism, oceanic islands, marginal and remnant seas, and Early Ordovician collisional granitoids. We have revealed a number of subunits (sedimentary sequences and igneous complexes) in the complexes and reconstructed their geodynamic settings. The tectonic evolution of the Dzhida island-arc system comprises five stages: (1) ocean opening (Late Riphean); (2) subduction and initiation of an island arc (Vendian-Early Cambrian); (3) subduction and development of a mature island arc (Middle-Late Cambrian); (4) accretion and formation of local collision zones and remnant basins (Early Ordovician-Devonian); and (5) postcollisional strike-slip faulting (Carboniferous-Permian).
Ultrapotassic basites in the Central Chukchi region and their role in genesis of Sn-bearing granites
Authors: Efremov S.V. , Kozlov V.D.
Published: March 2007

Analysis of the genetic relationship of Sn-bearing granitoids with ultrapotassic basic magmatism showed that their metallogeny was determined by the geochemistry of a specific reservoir localized in the continental lithosphere mantle (metasomatized mantle). The granitoid formation is well explained by the binary model of mixing of primary melts (products of the metasomatized mantle) with the continental crustal material. Geochemical studies of basic magmatism of different ages showed that the specific lithosphere reservoir formed in the Middle-Late Jurassic and existed at least till the late Late Cretaceous, i.e., during both tin metallogenic epochs of the Chukchi region.
“Where's the Spinning Wheel?” Frank Sinatra and Working-Class Alienation in Young at Heart
Authors: MCNALLY KAREN
Published: March 2007

In a profile of Frank Sinatra published in 1955, in the midst of the star's second defining career ascent, Time magazine declared, “His new success spreads like a Hoboken cargo net across almost every area of showbusiness.”1 Time's use of Sinatra's urban industrial background to describe his extraordinary success is typical of the commentary surrounding the star in the 1950s which cast him as a working-class interloper and betrayed the problematic class dynamics frequently denied by post-war America's dominant culture. Sinatra's non-conformist behaviour, aggressive ambition, extreme experiences of success and failure, and the screen characters through which he portrayed alienation and disenfranchisement combined with this type of unsubtle critique in the development of Sinatra's conspicuous working-class star identity.
Prevalence, spatial distribution and the effect of control measures on louping-ill virus in the Forest of Bowland, Lancashire
Authors: LAURENSON M. K. , McKENDRICK I. J. , REID H. W. , CHALLENOR R. , MATHEWSON G. K.
Published: March 2007

The complex pathogen–host–vector system of the tick-borne louping-ill virus causes economic losses to sheep and red grouse in upland United Kingdom. This paper examines the spatial distribution, incidence and effect of control measures on louping-ill virus in the Bowland Fells of Lancashire. Seroprevalence in sheep at the beginning of the study varied within the area and was affected significantly by the frequency of acaricide treatment. There was a clear decrease over 5 years in the effective force of infection on farms implementing a vaccination programme, irrespective of acaricide treatment regime, however, only one third of farms apparently eliminated infection. On farms where vaccination did not occur or where vaccination was carried out intermittently, the estimated force of infection was variable or possibly increased. Thus, as befits a complex host–pathogen system, reductions in prevalence were not as dramatic as predicted; we discuss the potential explanations for these observations.
Prediction of epidemic cholera due toVibrio choleraeO1 in children younger than 10 years using climate data in Bangladesh
Authors: MATSUDA F. , ISHIMURA S. , WAGATSUMA Y. , HIGASHI T. , HAYASHI T. , FARUQUE A. S. G. , SACK D. A. , NISHIBUCHI M.
Published: March 2007

To determine if a prediction of epidemic cholera using climate data can be made, we performed autoregression analysis using the data recorded in Dhaka City, Bangladesh over a 20-year period (1983–2002) comparing the number of children aged <10 years who were infected withVibrio choleraeO1 to the maximum and minimum temperatures and rainfall. We formulated a simple autoregression model that predicts the monthly number of patients using earlier climate variables. The monthly number of patients predicted by this model agreed well with the actual monthly number of patients where the Pearson's correlation coefficient was 0·95. Arbitrarily defined, 39·4% of the predicted numbers during the study period were within 0·8–1·2 times the observed numbers. This prediction model uses the climate data recorded 2–4 months before. Therefore, our approach may be a good basis for establishing a practical early warning system for epidemic cholera.
A MESSAGE FROM THE EDITORS
Authors: Capper Charles , La Vopa Anthony , Phillipson Nicholas
Published: March 2007

This issue marks an important stage in the Journal's development. In our original mission statement we recognized that Modern Intellectual History was likely in the first instance to be devoted to publishing work on intellectual history that was essentially Western in orientation and we looked forward to the day in which it would be possible to extend our reach to non-Western as well as Western history.
BEYOND CULTURE-CONTACT AND COLONIAL DISCOURSE: “GERMANISM” IN COLONIAL BENGAL
Authors: SARTORI ANDREW
Published: March 2007

This essay will explore the presence of Germany as a key trope of Bengali nationalist discourse in the late nineteenth century and the early twentieth. It will problematize the exhaustiveness of a conventional spectrum of interpretation in the analysis of colonial intellectual history that has been defined at one extreme by the cultural violence of colonial interpellation and at the other by a hermeneutic conception of authentic intercultural encounter across the limits of great traditions. When Bengalis actually began to interact directly with Germans and German thought, it was an encounter whose parameters had already been deeply determined in the course of the preceding forty or fifty years. But I shall also argue that this appeal to the trope of Germany emerged from within a more complex, multilateral configuration in which “Germany” was itself a key figure of Victorian discourses in Britain itself.
SELF, SPENCER AND SWARAJ: NATIONALIST THOUGHT AND CRITIQUES OF LIBERALISM, 1890–1920
Authors: KAPILA SHRUTI
Published: March 2007

In giving a historically specific account of the self in early twentieth-century India, this article poses questions about the historiography of nationalist thought within which the concept of the self has generally been embedded. It focuses on the ethical questions that moored nationalist thought and practice, and were premised on particular understandings of the self. The reappraisal of religion and the self in relation to contemporary evolutionary sociology is examined through the writings of a diverse set of radical nationalist intellectuals, notably Shyamji Krishnavarma, Bal Gangadhar Tilak and Har Dayal, and this discussion contextualizes Mohandas Gandhi. Over three related sites of public propaganda, philosophical reinterpretation and individual self-reinvention, the essay charts a concern with the ethical as a form of critique of liberalism and liberal nationalism. While evolutionism and liberalism often had a mutually reinforcing relationship, the Indian critique of liberalism was concerned with the formation of a new moral language for a politics of the self.
GEOGRAPHIES OF SUBJECTIVITY, PAN-ISLAM AND MUSLIM SEPARATISM: MUHAMMAD IQBAL AND SELFHOOD
Authors: MAJEED JAVED
Published: March 2007

This essay focuses on the oppositional politics expressed in the historical geography of the Persian and Urdu poetry of Muhammad Iqbal (1877–1938), showing how it emerges from, and breaks with, Urdu and Persian travelogues and poetry of the nineteenth century. It explores the complex relationships between the politics of Muslim separatism in South Asia and European imperialist discourses. There are two defining tensions within this politics. The first is between territorial nationalism and the global imaginings of religious identity, and the second is between the homogenizing imperatives of nationalism and the subjectivity of individual selfhood. These tensions are reflected in the composite geography of Iqbal's work, which contains three elements: a sacred space, a political territoriality and the interiority of subjectivity. But these elements are in conflict with each other; in particular, the space of interiority in his poetry conflicts with the realm of politics in the external world.
Assessing elastic Coulomb stress transfer models using seismicity rates in southern California and southwestern Japan
Authors: Mallman Ellen P. , Zoback Mark D.
Published: March 2007

We investigated whether observed changes in seismicity rate following the 1992 Landers and 1995 Kobe earthquakes correspond with predictions from Coulomb stress transfer models. To quantify the relationship between Coulomb stress change and seismicity rate change, we compared spatial changes in observed seismicity rates to the modeled changes in Coulomb failure stress (ΔCFS) for the two subject earthquakes. We begin with the simplest and most common ΔCFS model, which assumes that regional stress orientations are uniform and the stress change is resolved on optimally oriented strike‐slip planes. We then extended the ΔCFS models to include the more geophysically realistic assumptions of spatially varying regional stress orientations and optimally oriented planes in three dimensions. For all the tested ΔCFS models, we found that virtually everywhere seismicity rate changes could be resolved, the rate increased regardless of whether the ΔCFS theoretically promoted or inhibited failure and that we were not able to reliably resolve seismicity rate decreases. An improvement in the correlation between the sign of the ΔCFS and where rate increases occur when estimating the ΔCFS on optimally oriented planes in three dimensions rather than two dimensions is a consequence of using optimally oriented planes and the ability to primarily observe rate increases. The region of positive ΔCFS increases by allowing more degrees of freedom so the correlation with positive rate change appears to increase. The areas of highest seismicity rate following the main shock did not correlate with the sign or the magnitude of the ΔCFS. Rather, the areas most active after the main shock were also the most active before the main shock.
A seesaw structure in SLP anomalies between the Beaufort Sea and the Barents Sea
Authors: Wu Bingyi , Johnson Mark A.
Published: March 2007

This paper reveals a new mode of winter (October–March) monthly mean atmospheric intraseasonal variability characterized by a seesaw structure in sea level pressure (SLP) anomalies between the Barents Sea and the Beaufort Sea with an equivalent barotropic structure. The Beaufort High varies out of phase with the Siberian High. Compared to the Arctic Oscillation (AO) and the dipole anomaly, the effect of this mode on Fram Strait sea ice flux is the most important so far, although it accounts for only 9.1% of the variance. The Beaufort High itself is not crucial for sea ice flux through Fram Strait.
Effects of carbon dioxide and climate change on ocean acidification and carbonate mineral saturation
Authors: Cao Long , Caldeira Ken , Jain Atul K.
Published: March 2007

We use an earth system model of intermediate complexity to show how consideration of climate change affects predicted changes in ocean pH and calcium carbonate saturation state. Our results indicate that consideration of climate change produces second‐order modifications to ocean chemistry predictions made with constant climate; these modifications occur primarily as a result of changes in sea surface temperature, and climate‐induced changes in dissolved inorganic carbon concentrations. Under a CO2 emission scenario derived from the WRE1000 CO2 stabilization concentration pathway and a constant climate, we predict a 0.47 unit reduction in surface ocean pH relative to a pre‐industrial value of 8.17, and a reduction in the degree of saturation with respect to aragonite from a pre‐industrial value of 3.34 to 1.39 by year 2500. With the same CO2 emissions but the consideration of climate change under a climate sensitivity of 2.5°C the reduction in projected global mean surface pH is about 0.48 and the saturation state of aragonite decreases to 1.50. With a climate sensitivity of 4.5°C, these values are 0.51 and 1.62, respectively. Our study therefore suggests that future changes in ocean acidification caused by emissions of CO2 to the atmosphere are largely independent of the amounts of climate change.
Spatial and temporal constraints on sources of seismic anisotropy: Evidence from the Scottish highlands
Authors: Bastow I. D. , Owens T. J. , Helffrich G. , Knapp J. H.
Published: March 2007

Routine SKS splitting analyses of seismic anisotropy usually suffer from limitations in station density that hinder attempts to place spatial constraints on anisotropic fabrics. Data from a ∼20 km station spacing network in Scotland show that splitting parameters vary considerably (δt = 0.45–1.5 s; ϕ = 49–128°) over short (10–20 km) length scales. Improved spatial constraints then lead to tighter temporal constraints on the anisotropic sources. Asthenospheric fabrics due to Tertiary rifting and present day plate motions do not strongly influence our results that instead correlate with lithospheric scale trends inferred from surface geology. Splitting observations track Scotland's tectonic history from the Precambrian emplacement of crustal basement and through the activation of large‐scale faulting and thrusting during the Caledonian Orogeny. The shallow lithosphere beneath Scotland has preserved a fossil anisotropic signature up to hundreds of millions of years after it was formed.
National Lightning Detection Network (NLDN) performance in southern Arizona, Texas, and Oklahoma in 2003–2004
Authors: Biagi Christopher J. , Cummins Kenneth L. , Kehoe Kenneth E. , Krider E. Philip
Published: March 2007

Four field campaigns were conducted in southern Arizona (AZ) and in northern Texas and southern Oklahoma (TX‐OK) in 2003 and 2004 to evaluate the performance of the U.S. National Lightning Detection Network™ (NLDN) in detecting cloud‐to‐ground (CG) lightning after an upgrade in 2002 and 2003. The 2‐year average flash detection efficiency (DE) in AZ was 93% (1024/1097), and the measured (first plus subsequent) stroke DE was 76% (2746/3620). The corresponding values in TX‐OK were 92% (338/367) and 86% (755/882), respectively. After correcting for the time resolution of the video camera (16.7 ms), we estimate that the actual NLDN stroke DE and video multiplicities were about 68% and 3.71 in AZ and 77% and 2.80 in TX‐OK. The average DE for negative first strokes (92%) was larger than the measured DE for subsequent strokes that produced a new ground contact (81%) and the DE for subsequent strokes that remained in a preexisting channel (67%). The primary cause of the NLDN missing strokes was that the peak of the radiated electromagnetic field was below the NLDN detection threshold. The average estimated peak current (Ip) of negative first strokes and the average multiplicity of negative flashes varied from storm to storm and between the two regions, but this variability did not affect the DE as long as the recording sessions had more than 60 flashes. By analyzing the NLDN locations of subsequent strokes that remained in the same channel as the first stroke we infer that the median random position error of the NLDN was 424 m in AZ and 282 m in TX‐OK. An evaluation of the classification of lightning type by the NLDN (i.e., CG stroke versus cloud pulse) showed that 1.4–7% (6/420 to 6/86) of the positive NLDN reports with an Ip ≤ 10 kA in TX‐OK were produced by CG strokes; 4.7–26% (5/106 to 5/19) of the positive reports with 10 kA < Ip ≤ 20 kA were CGs; and 67–95% (30/45 to 30/32) of the reports with Ip ≥ +20 kA were CG strokes. Some 50–87% (52/104 to 52/60) of the negative, single‐stroke NLDN reports in AZ and TX‐OK with ∣Ip∣ ≤ 10 kA were produced by CG flashes. Both the upper and lower bounds in these classification studies have observational biases.
Developing a high‐resolution wind map for a complex terrain with a coupled MM5/CALMET system
Authors: Yim Steve H. L. , Fung Jimmy C. H. , Lau Alexis K. H. , Kot S. C.
Published: March 2007

This study investigates the wind energy potential in Hong Kong, a region with a complex terrain, by coupling the prognostic MM5 mesoscale model with the CALMET diagnostic model to produce high‐resolution wind fields. Hourly wind fields were simulated for the entire year of 2004. The MM5 simulations were performed on a nested grid from 40.5 km down to 1.5 km horizontal resolution. The CALMET meteorological model was used in a domain that includes the entire Hong Kong region with a high horizontal resolution of 100 m. The MM5 model wind field (1.5 km horizontal resolution) output was input into the CALMET diagnostic meteorological model every hour along with an objective analysis procedure using all available observations. Verification was achieved through two steps. In the first step, the data from three meteorological surface stations that were not assimilated into the CALMET model were compared horizontally with the simulated wind fields. In the second step, the simulated wind fields were compared vertically with the vertical wind profile collected from two upper air sounding stations. The results of this study identified the locations of the highest wind energy potential in HK down to 100 m resolution.
Self-fields effects on gain in a free-electron laser with helical wiggler and axial magnetic field
Authors: Esmaeilzadeh Mahdi , Willett Joseph E.
Published: March 2007

A theory for gain in a free-electron laser with helical wiggler and axial magnetic field in the presence of self-fields is presented. It is found that for group I orbits, gain decrement is obtained relative to the absence of the self-fields, while for group II orbit gain enhancement is obtained. The gain decrement and enhancement are due to the diamagnetic and paramagnetic effects of the self-magnetic field, respectively.
Nonisothermal chemical model of reactive sputtering
Authors: Barybin Anatoly A. , Shapovalov Victor I.
Published: March 2007

A kinetic model of reactive sputtering is proposed to modify Berg’s model by taking into account the true chemical interaction at solid surfaces of the target, substrate, and chamber wall having different temperatures. Any chemical reaction is correctly characterized by the rate constant k(T) rather than the sticking coefficient α, as it was previously done by Berg and other authors. Such a coefficient is solely inherent in the physical adsorption as an initial stage preceding the chemical interaction at the solid surfaces. Appropriate kinetic equations are derived by examining in detail the particle fluxes sputtered from the target and deposited onto the substrate and wall, as well as the surface chemical reactions. The kinetic equation for the target process has proved fully identical in form with that for the nonisothermal physical adsorption, whereas the kinetic equation for the substrate and wall processes are of a more complicated form. Analysis of the steady-state situation shows an advantage of the developed nonisothermal model over the isothermal Berg model for fitting to experimental data.
Defect states in Nd3+-doped CaAl2O4:Eu2+
Authors: Wang Yuhua , Wang Lei
Published: March 2007

Defects induced by Nd3+ are crucial for the improvement of persistent luminescence properties of CaAl2O4:Eu2+. Those defects were investigated with thermoluminescence and positron annihilation techniques. The results indicate that the trap levels in CaAl2O4:Eu2+,Nd3+ are much deeper than that in CaAl2O4:Eu2+, and the structure of those traps was not normally expected Ca2+ vacancies but complex clusters consisting of a Ca2+ vacancy and two Nd3+ ions. A possible mechanism based on the structure of those defects is presented and discussed.
Annealing of C60o gamma radiation-induced damage in n-GaN Schottky barrier diodes
Authors: Umana-Membreno G. A. , Dell J. M. , Parish G. , Nener B. D. , Faraone L. , Keller S. , Mishra U. K.
Published: March 2007

The effect of isochronal thermal annealing on Ni∕n-GaN Schottky barrier diodes exposed to a total accumulated gamma-ray dose of 21 Mrad(Si) has been investigated using capacitance-voltage (C-V) and current-voltage (I-V) measurements, while capacitance deep-level transient spectroscopy (DLTS) has been employed to monitor the evolution and annihilation of radiation-induced defects during thermal annealing. Annealing temperatures up 160 °C were found to improve device I-V characteristics; however, thermal annealing above 250 °C resulted in: (a) Degradation of both forward and reverse I-V characteristics, (b) reduction in free carrier concentration, and (c) a decrease in the concentration of radiation-induced defects, as evidenced by DLTS measurements. Following annealing above 350 °C, the radiation-induced defects were no longer detectable using DLTS. Analysis of the thermally induced reduction in radiation-induced defect concentration indicated that the dominant defect-annihilation process has a mean activation energy of 1.8 eV. The physical origin of radiation-induced defects, and of defects involved in their annihilation process, is discussed in the perspective of published theoretical calculations of native defect diffusion mechanisms in GaN.
Faraday rotation spectra analysis of Bi-substituted mixed rare-earth iron garnet crystals in optical communication band
Authors: Xu Z. C. , Yan M. , Li Miao , Zhang Z. L. , Huang M.
Published: March 2007

Through combining two types of Bi-substituted rare-earth iron garnet crystals with opposite Faraday rotation wavelength coefficient (FWC) signs, the Bi-substituted mixed rare-earth iron garnet (Tb3−x−yYbyBixFe5O12) crystals with low FWC are used in optical isolators for broadband optical communication. However, the Faraday rotation (FR) spectra of bismuth-substituted mixed rare-earth iron garnet crystals have not yet been theoretically studied in the optical communication band [wavelength (λ)=1.5–1.62μm]. In order to interpret their FR spectra, a theory based on molecular-orbital levels of Fe3+ in tetrahedral (d) and octahedral (a) sites is used. It is shown that in the case of higher Bi3+ substitution, FR depends mainly on the contributions of Fe3+ in the octahedral sites. Furthermore, two types of rare-earth ions (Tb3+ and Yb3+) moderate the contributions to FR from Fe3+ in octahedral and decahedral sites and eventually have caused that Tb3−x−yYbyBixFe5O12 crystals has a near-zero FWC.
High performance [Bi3Fe5O12∕Sm3Ga5O12]m magneto-optical photonic crystals
Authors: Khartsev S. I. , Grishin A. M.
Published: March 2007

We report the properties of one-dimensional heteroepitaxial all-garnet magneto-optical (MO) photonic crystals (MOPCs) composed of alternating MO-active Bi3Fe5O12 (BIG) and transparent Sm3Ga5O12 (SGG) quarter-wavelength layers grown by rf-magnetron sputtering on Ca,Mg,Zr:Gd3Ga5O12(111) and Gd3Sc2Ga3O12(001) crystals. MOPCs’ spectra, as designed, exhibit a stop band structure and a band gap with the transmittance central peak at 750nm caused by light localization in the half-wavelength BIG cavity. A series of MOPCs with different numbers of [BIG∕SSG]m reflectors (m=4, 5, and 6) has been fabricated to optimize the specific Faraday rotation θF (deg∕μm) and MO-quality factor Q(deg)=2∣θF∣/absorption coefficient. A close BIG-to-SGG lattice match enabled significant improvement of [Bi3Fe5O12∕Sm3Ga5O12]m properties compared to previously reported [Bi3Fe5O12∕Y3Fe5O12]m [S. Kahl and A. M. Grishin, Appl. Phys. Lett. 84, 1438 (2004)] and [Bi3Fe5O12∕Gd3Ga5O12]m [S. I. Khartsev and A. M. Grishin, Appl. Phys. Lett. 87, 122504 (2005)] pulsed laser deposited photonic crystals. At the resonance wavelength λ=750nm, θF=−20.5deg∕μm and Q=66deg represent the highest MOPC performance achieved so far. Respectively, these are 470% and 31% enhancements compared to a single layer Bi3Fe5O12 film Faraday rotator with equivalent thickness.
The role of oxygen vacancies in epitaxial-deposited ZnO thin films
Authors: Shan F. K. , Liu G. X. , Lee W. J. , Shin B. C.
Published: March 2007

ZnO thin films were epitaxial deposited on sapphire (0001) substrates at various temperatures by using the pulsed laser deposition (PLD) technique. An x-ray diffractometer (XRD) was used to investigate the structural properties of the thin film. It was found that all of the thin films were (0002) oriented and the intensity of (0002) peak increased with the increasing growth temperature. The ϕ-scans for the thin films indicated that the thin film grown at a temperature higher than 400 °C had an epitaxial relation with the substrate. An atomic force microscope (AFM) was used to investigate the surface morphologies of the thin films. The surface roughness and grain size of the thin films increased with increasing growth temperature. A double-beam spectrophotometer was used to measure the transmittances of the thin films. The band gap energies of the thin films were calculated by linear fitting the absorption edges for high-quality thin films. A spectrometer was used to investigate the photoluminescent (PL) properties of the thin films. It was discovered that all of the thin films showed two emissions. One was the near band edge (NBE) emission; the other was the broad deep-level (DL) emission. After checking the PL of the thin films on a different date, the aging effect of the ZnO thin film on the sapphire substrate deposited by PLD was observed. It was revealed that, the NBE emissions were enhanced and the DL emissions were decreased with time. To find the reason why the DL emission decreased with time, the as-deposited thin films were annealed at 800 °C in a N2 and O2 atmosphere for 30 min, respectively. The surface morphologies and the transmittances of the annealed thin films were investigated by the AFM and spectrophotometer. The surface roughness and the transmittance decreased much after annealing. The PL measurements for the annealed thin films indicated that, the DL emission of the thin film annealed in N2 was enhanced and that annealed in O2 was quenched. It was suggested that the oxygen vacancies, instead of zinc interstitials, played the most important role for DL emissions in ZnO thin films deposited by PLD.
Shock tube/time-of-flight mass spectrometer for high temperature kinetic studies
Authors: Tranter Robert S. , Giri Binod R. , Kiefer John H.
Published: March 2007

A shock tube (ST) with online, time-of-flight mass spectrometric (TOF-MS) detection has been constructed for the study of elementary reactions at high temperature. The ST and TOF-MS are coupled by a differentially pumped molecular beam sampling interface, which ensures that the samples entering the TOF-MS are not contaminated by gases drawn from the cold end wall thermal boundary layer in the ST. Additionally, the interface allows a large range of postshock pressures to be used in the shock tube while maintaining high vacuum in the TOF-MS. The apparatus and the details of the sampling system are described along with an analysis in which cooling of the sampled gases and minimization of thermal boundary layer effects are discussed. The accuracy of kinetic measurements made with the apparatus has been tested by investigating the thermal unimolecular dissociation of cyclohexene to ethylene and 1,3-butadiene, a well characterized reaction for which considerable literature data that are in good agreement exist. The experiments were performed at nominal reflected shock wave pressures of 600 and 1300Torr, and temperatures ranging from 1260to1430K. The rate coefficients obtained are compared with the earlier shock tube studies and are found to be in very good agreement. As expected no significant difference is observed in the rate constant between pressures of 600 and 1300Torr.
Hydrodynamic model for spin-polarized electron transport in semiconductors
Authors: Villegas-Lelovsky L.
Published: March 2007

We extend the hydrodynamic model of the Boltzmann equation by taking into account the spin of the nonequilibrium carriers injected into semiconducting systems. This spin-resolved hydrodynamic description goes beyond the usual drift-diffusion type approaches in a way that the temporal derivatives of the current densities are considered. This allows us to investigate the transient dynamics of spin-polarized packets in the diffusive and ballistic transport regimes. We have properly included the spin-polarized carriers from doping by solving our set of continuity equations and the Poisson equation self-consistently. We determine the spin-polarization landscapes (time and position) of the carrier density (n↑−n↓)∕(n↑+n↓) and the current density (j↑−j↓)∕(j↑+j↓). While in the uniformly doped system the carrier spin polarization has a slow decay, in the nonuniformly doped system it shows a drastic suppression in the interface. In contrast the current spin polarization exhibits an enhancement in this region. It can in principle be useful in designing submicron spintronic devices.
Electron flux controlled switching between electron beam induced etching and deposition
Authors: Toth Milos , Lobo Charlene J. , Hartigan Gavin , Ralph Knowles W.
Published: March 2007

Electron beam induced deposition (EBID) and etching (EBIE) are promising methods for the fabrication of three-dimensional nanodevices, wiring of nanostructures, and repair of photolithographic masks. Here, we study simultaneous EBID and EBIE, and demonstrate an athermal electron flux controlled transition between material deposition and etching. The switching is observed when one of the processes has both a higher efficiency and a lower precursor partial pressure than the other. This is demonstrated in two technologically important systems: during XeF2-mediated etching of chrome on a photolithographic mask and during deposition and etching of carbonaceous films on a semiconductor surface. Simultaneous EBID and EBIE can be used to enhance the spatial localization of etch profiles. It plays a key role in reducing contamination buildup rates during low vacuum electron imaging and deposition of high purity nanostructures in the presence of oxygen-containing gases.
Raman investigations of rare earth orthovanadates
Authors: Santos C. C. , Silva E. N. , Ayala A. P. , Guedes I. , Pizani P. S. , Loong C.-K. , Boatner L. A.
Published: March 2007

Polarized Raman spectroscopy has been used to obtain the room-temperature phonon spectra of the series of rare earth orthovanadate single crystals: SmVO4, HoVO4, YbVO4, and LuVO4. The observed Raman frequencies follow the overall mode distribution expected for REVO4 compounds with the tetragonal zircon structure. The variation of the mode frequency with atomic number across the lanthanide orthovanadate series was investigated, and the trend exhibited by the internal modes was explained by considering the force constants of VO4 tetrahedron.
Effect of annealing current density on the microstructure of nanocrystalline FeCuNbSiB alloy
Authors: Gupta P. , Gupta A. , Principi G. , Maddalena A. , Bernstorff S. , Amenitsch H.
Published: March 2007

The amorphous Fe73.9Nb3.1Cu0.9Si13.2B8.9 alloy has been submitted to current annealing at four different current densities ranging from 3.3×107to3.9×107A∕m2. The effect of annealing current density on the structure of the resulting nanocrystalline phase in the same alloy has been studied using in situ wide angle x-ray scattering and small angle x-ray scattering measurements. Some information about the magnetic properties has been obtained from Mössbauer measurements. It is found that higher current density results in significant grain refinement and decrease in the lattice parameter of the nanocrystalline phase, as well as lowering of x-ray contrast between nanocrystalline grains and the amorphous grain boundary phase. These results suggest a variation, with increasing current density, in the composition of the nanocrystalline grains and/or the amorphous grain boundary phase and are corroborated by ex situ Mössbauer spectroscopy measurements on current annealed samples.
Atomic and electronic structure of amorphous and crystalline hafnium oxide: X-ray photoelectron spectroscopy and density functional calculations
Authors: Perevalov T. V. , Gritsenko V. A. , Erenburg S. B. , Badalyan A. M. , Wong Hei , Kim C. W.
Published: March 2007

The atomic structure of amorphous and crystalline hafnium oxide (HfO2) films was examined using x-ray diffractometry and Hf edge x-ray absorption spectroscopy. According to the x-ray photoelectron spectroscopy and band data calculated by the density functional method, we found that the valence band of HfO2 consists of three subbands separated by ionic gaps. The upper subband is formed by O 2p, Hf 4f, and Hf 5d states; the intermediate subband is formed by O 2s and Hf 4f states, whereas the lower narrow subband is mainly formed by Hf 5p states. The energy gap of amorphous HfO2 is 5.7eV as determined by electron energy loss spectroscopy. The band calculation results indicate the existence of light (0.3m0) and heavy (8.3m0) holes in the HfO2 film and the effective mass of electron lies in the interval of 0.7m0–2.0m0.
Growth-temperature- and thermal-anneal-induced crystalline reorientation of aluminum on GaAs (100) grown by molecular beam epitaxy
Authors: Liu H. F. , Chua S. J. , Xiang N.
Published: March 2007

The authors investigated the growth of Al thin films on GaAs (100) substrates by molecular beam epitaxy. It is found that the growth at 550°C results in a texture that consists of (100)Al[010]‖(100)GaAs[011] and (100)Al[010]‖(100)GaAs[010] rotated 45° with respect to each other, while the growth at 300°C leads to a mixture phase of (100)Al[010]‖(100)GaAs[011] and (110)Al[001]‖(100)GaAs[01¯1¯]. In situ annealing of the Al film grown at 300°C causes a reorientation of the crystalline from (100)Al[010]‖(100)GaAs[011] to (110)Al[001]‖(100)GaAs[01¯1¯]. The grain sizes of the Al film are increased by the increased growth temperature and in situ annealing; the ratio of the exposed to the covered surface is not changed significantly by changing the growth temperature but decreased by annealing; and the small islands in between the large ones are removed by annealing. These observations are explained based on island migration and coalescence.
Schottky contact barrier height extraction by admittance measurement
Authors: Jiang Yu-Long , Luo Jia , Yao Ye , Lu Fang , Ru Guo-Ping , Qu Xin-Ping , Li Bing-Zong
Published: March 2007

Different from the conventional current-voltage and capacitance-voltage methods, Schottky contact barrier height extraction by admittance measurement is proposed and discussed in this paper. In this method, the barrier height can be simply extracted from the difference between the measured admittance at zero bias and a reasonably high forward bias. Both simulation results and experimental data demonstrate that the proposed method is effective not only for extraction of Schottky contacts with higher barrier heights (>0.4eV) but also for extraction of those with moderately lower barrier heights (0.2–0.4eV).