bluuebunny/crossref_metadata_2025 huggingface dataset:
Russian Buddhists in Tibet, from the end of the nineteenth century – 1930
Authors: Andreyev Alexander
Published: August 2008

The article offers a survey of religious contacts maintained between Tibet and Russian Buddhists, the ethnic Buryats and Kalmyks, from the late 19th C. to the 1930s. Chronologically, the story falls into two parts, the dividing point being the Bolshevik revolution of 1917. The focus in the first portion is on the Russian Buddhist colony in Lhasa centred around the Gomang Datsang (school) of the Drepung monastery, its emergence and growth in the early 20th C., in the wake of Russo-Tibetan rapprochement brought about by a Buryat scholar-monk and adviser of the 13th Dalai Lama, Agvan Dorjiev. The tsarist government tried to use their Buddhist connection with Lhasa to political ends – in January 1904, shortly after the beginning of the British military invasion of Tibet, they sent a secret Kalmyk reconnaissance mission to Lhasa under a Cossack subaltern, Naran Ulanov, assisted by a cleric (bakshi) Dambo Ulianov. The latter part of the article concentrates on the dramatic post-revolutionary period. It begins with the story of the Kalmyk refugees in Turkey and their abortive attempt to emigrate to Tibet. There's also a detailed discussion of the endeavours by Soviet leaders to win the Dalai Lama over, by employing the loyal Buryats and Kalmyks for their secret missions to the Potala. The key figures behind this scheme were the Soviet foreign minister, G. V. Chicherin, and the same Agvan Dorjiev, posing as the Dalai Lama's representative in the USSR. As a result of the Bolshevik propaganda, many of the Buryat and Kalmyk residents in Lhasa began to return to their homeland in the 1920s. The crackdown on Buddhism in Soviet Russia put an end to the Moscow–Lhasa political dialogue. Hence all connections between the Buryat and Kalmyk Buddhists and their religious “Mecca” were deliberately cut by the Soviet authorities by 1930.
“Ingrams Peace”, Ḥaḍramawt, 1937–40. Some Contemporary Documents
Authors: Smith G. Rex
Published: August 2008

In February 1937, a peace between the Hadramawt sultanates, the Qu[ain]aytī and Kathīrī and their tribes, totally unprecedented in the history of that region, was brought about essentially by the efforts of two men: Sayyid Sir Abū Bakr al-Kāf and Harold Ingrams, the first political officer in Hadramawt. This peace was known universally thereafter as “Ingrams Peace”, although the word “truce” is much in evidence in the contemporary documents studied below.

The prime object of this article is to examine in some detail some of the contemporary British documents directly or indirectly relevant to the phenomenon (for such it undoubtedly was!) of the late 1930s–early 1940s called “Ingrams Peace”. It is quite unashamedly a view of events through British eyes, through the eyes of the key players in the drama. They are allowed as far as is possible to speak for themselves. Let us first introduce the characters involved and set the scene.
The Dvaravati “Buddha on a Monster” Stelae: A Possible Interpretation
Authors: Tiffin Sarah , Stuart-Fox Martin
Published: August 2008

Providing convincing explanations for objects that are unique to Dvaravati is particularly challenging given that our knowledge of the polity is sketchy to say the least. One particularly fascinating group of such objects comprises a number of stelae depicting the Buddha apparently standing on the head of some beast or “monster”. The central Buddha figure is usually flanked by two gods, probably Indra and Brahma, or two bodhisattvas, or just two attendants. The “monster” has been interpreted as some combination of the vehicles of Visnu (Garuda), Siva (bull) and/or Brahma (hamsa or goose), or as Garuda, or Surya, the Sun God. There are no Indian prototypes for these objects, which are found only in the Dvaravati sculptural style.
Remote sensing observatory validation of surface soil moisture using Advanced Microwave Scanning Radiometer E, Common Land Model, and ground based data: Case study in SMEX03 Little River Region, Georgia, U.S.
Authors: Choi Minha , Jacobs Jennifer M. , Bosch David D.
Published: August 2008

Optimal soil moisture estimation may be characterized by intercomparisons among remotely sensed measurements, ground‐based measurements, and land surface models. In this study, we compared soil moisture from Advanced Microwave Scanning Radiometer E (AMSR‐E), ground‐based measurements, and a Soil‐Vegetation‐Atmosphere Transfer (SVAT) model for the Soil Moisture Experiments in 2003 (SMEX03) Little River region, Georgia. The Common Land Model (CLM) reasonably replicated soil moisture patterns in dry down and wetting after rainfall though it had modest wet biases (0.001–0.054 m3/m3) as compared to AMSR‐E and ground data. While the AMSR‐E average soil moisture agreed well with the other data sources, it had extremely low temporal variability, especially during the growing season from May to October. The comparison results showed that highest mean absolute error (MAE) and root mean squared error (RMSE) were 0.054 and 0.059 m3/m3 for short and long periods, respectively. Even if CLM and AMSR‐E had complementary strengths, low MAE (0.018–0.054 m3/m3) and RMSE (0.023–0.059 m3/m3) soil moisture errors for CLM and soil moisture low biases (0.003–0.031 m3/m3) for AMSR‐E, care should be taken prior to employing AMSR‐E retrieved soil moisture products directly for hydrological application due to its failure to replicate temporal variability. AMSR‐E error characteristics identified in this study should be used to guide enhancement of retrieval algorithms and improve satellite observations for hydrological sciences.
Total gaseous mercury exchange between water and air during cloudy weather conditions over Hongfeng Reservoir, Guizhou, China
Authors: Feng Xinbin , Wang Shaofeng , Qiu Guangle , He Tianrong , Li Guanghui , Li Zhonggen , Shang Lihai
Published: August 2008

Total gaseous mercury (TGM) exchange fluxes between air and water surface were measured using a dynamic flux chamber (DFC) coupled with a gaseous mercury analyzer at two sampling sites of Hongfeng reservoir in cloudy and rainy weather conditions. The concentrations of dissolved gaseous mercury (DGM) in water were also measured and indicated that DGM was supersaturated at most time during the sampling periods, which implied that the water body acted primarily as a source of mercury to the atmosphere. In general, TGM fluxes displayed a consistent diurnal pattern with peak fluxes at noon and minimum levels at early morning or night. However, this diurnal pattern was not clear when the weather was heavily cloudy and rainy with the maximum solar radiation of less than 140 W m−2. At this specific weather condition, a significantly positive correlation between TGM flux and relative humidity was observed. The behaviors of TGM flux over Hongfeng reservoir observed at cloudy weather conditions were some what different from those observed during mostly sunny weather conditions in Northern America and Europe. The empirical model developed based on the correlation between TGM flux and solar radiation during sunny days in Northern America was not applicable for estimation of TGM flux at cloudy and rainy weather conditions.
An annual quasidifference approach to water price elasticity
Authors: Bell David R. , Griffin Ronald C.
Published: August 2008

The preferred price specification for retail water demand estimation has not been fully settled by prior literature. Empirical consistency of price indices is necessary to enable testing of competing specifications. Available methods of unbiasing the price index are summarized here. Using original rate information from several hundred Texas utilities, new indices of marginal and average price change are constructed. Marginal water price change is shown to explain consumption variation better than average water price change, based on standard information criteria. Annual change in quantity consumed per month is estimated with differences in climate variables and the new quasidifference marginal price index. As expected, the annual price elasticity of demand is found to vary with daily high and low temperatures and the frequency of precipitation.
Singular value decomposition analyses of tropical tropospheric ozone determined from TOMS
Authors: Kim J. H. , Na S. , Martin R. V. , Seo K. H. , Newchurch M. J.
Published: August 2008

A controversial dispute in space‐based tropospheric ozone remote sensing is the puzzling discrepancy in the spatiotemporal distribution between residual‐based satellite ozone observations and biomass‐burning activity in the tropics during boreal winter. This study focuses on evaluation and analyses of two tropospheric ozone products determined from Earth Probe TOMS measurements: Convective Cloud Differential measurements (CCD) and Scan Angle measurements (SAM). Rather than using the typical station‐to‐station inter‐comparison with ozone sounding measurements, the evaluation was performed at the global scale using temporal and spatial patterns derived from Singular Value Decomposition (SVD) analyses. The satellite observations of ozone precursors from MOPITT CO and GOME NO2 serve as markers identifying airmasses influenced by biomass burning. The SVD analyses reveal that the SAM tropospheric ozone product is remarkably consistent (95% significance level) with the two measured ozone precursors, CO and NO2, in distribution as well as in seasonality. The analyses provide compelling evidence that there is no discrepancy between tropospheric ozone and its precursors during boreal winter.
In a changing climate weakening tropical easterly jet induces more violent tropical storms over the north Indian Ocean
Authors: Rao V. Brahmananda , Ferreira Camila C. , Franchito S. H. , Ramakrishna S. S. V. S.
Published: August 2008

Tropical Easterly Jet (TEJ) of summer monsoon over the north Indian ocean is weakening in recent years. The absolute easterly shear shows a strong negative correlation (significant at 99.9% level by students' two sided t‐test) with the number of severe storms suggesting that a decrease in easterly shear is favorable for the formation of more severe tropical storms. For the first time in recorded history a category 5 Hurricane formed in June 2007 together with two more severe tropical storms over the north Indian ocean. Thus if the present decreasing trend of TEJ intensity continues there is a strong likelihood of the formation of tropical cyclones of hurricane intensity even during the summer monsoon. Presently these intense systems are known to form only in the pre and post monsoon seasons, when the vertical wind shear is small.
Circulating CD34-Positive Cells Have Prognostic Value for Neurologic Function in Patients with past Cerebral Infarction
Authors: Taguchi Akihiko , Nakagomi Nami , Matsuyama Tomohiro , Kikuchi-Taura Akie , Yoshikawa Hiroo , Kasahara Yukiko , Hirose Haruka , Moriwaki Hiroshi , Nakagomi Takayuki , Soma Toshihiro , Stern David M , Naritomi Hiroaki
Published: August 2008

Increasing evidence points to a role for circulating endothelial progenitors, including populations of CD34-positive (CD34+) cells present in peripheral blood, in vascular homeostasis and neovascularization. In this report, circulating CD34+ cells in individuals with a history of cerebral infarction were correlated with changes in neurologic function over a period of 1 year. Patients with decreased levels of CD34+ cells displayed significant worsening in neurologic function, evaluated by the Barthel Index and Clinical Dementia Rating. These results support the hypothesis that levels of circulating CD34+ cells have prognostic value for neural function, consistent with their potential role in maintaining cerebral circulation.
Additive prognostic value of cardiopulmonary exercise testing in elderly patients with heart failure
Authors: Scardovi Angela B. , De Maria Renata , Celestini Andrea , Perna Silvia , Coletta Claudio , Feola Mauro , Aspromonte Nadia , Rosso Gian Luca , Carunchio Alessandro , Ferraironi Alessandro , Pimpinella Alessandro , Ricci Roberto
Published: August 2008

To date, the role of CPET (cardiopulmonary exercise testing) for risk stratification in elderly patients with HF (heart failure) with depressed or preserved ventricular function has not been evaluated. In the present study, we analysed whether CPET is useful in predicting outcome in this population. A total of 220 NYHA (New York Heart Association) class I–III patients with HF ≥70 years of age [median age, 75 years; 23% had NYHA class III; and 59% had preserved ventricular systolic function (left ventricular ejection fraction ≥40%)] performed maximal CPET (peak expiratory exchange ratio >1.00). Median peak oxygen uptake was 11.9 ml·kg−1 of body weight·min−1, median V̇E/V̇CO2 slope (slope of the minute ventilation/carbon dioxide production ratio) was 33.2 and 45% had an EVR (enhanced ventilatory response) to exercise (V̇E/V̇CO2 slope ≥34). During 19 months of follow-up, 94 patients (43%) met the combined end point of death and hospital admission for worsening HF, arrhythmias or acute coronary syndromes. By Cox multivariable analysis, a creatinine clearance of <50 ml/min {HR (hazard ratio), 1.657 [95% CI (confidence interval), 1.055–2.602]} and EVR [HR, 1.965 (95% CI, 1.195–3.231)] were the best predictors of outcome, while ventricular function had no influence on prognosis. In conclusion, in elderly patients with HF, a steeper V̇E/V̇CO2 slope provides additional information for risk stratification across the spectrum of ventricular function and identifies a high-risk population, commonly not considered in exercise testing guidelines.
Thermo-optical modeling of high power operation of 2 μm codoped Tm,Ho solid-state lasers
Authors: Louchev Oleg A. , Urata Yoshiharu , Yumoto Masaki , Saito Norihito , Wada Satoshi
Published: August 2008

The results of coupled thermo-optical modeling of Tm,Ho solid-state laser operation are reported. A rate dynamics model integrated together with a TEM00 distribution for the total number of stimulated photons is coupled with a two-dimensional time-dependent heat transfer model. The heat transfer model includes absorption, heat release, and transfer inside the crystal as well as the thermal effect of the spontaneously emitted infrared radiation. In water cooled crystal operation this radiation is shown to be absorbed within the water boundary layer, producing significant inhibition of dissipation of the heat released inside the crystal. This effect leads to crystal superheating and significant inhibition of laser energy output. Absorption loss, in particular, due to water vapor present in the cavity is found to decrease significantly laser pulse energy. Numerical results are compared to previous (Tm,Ho:yttrium lithium fluoride) and new (Tm,Ho:ceramic yttrium aluminum garnet) experimental data and discussed within the framework of the computational model and simplified analytical approximations.
Optical emission study of a doped diamond deposition process by plasma enhanced chemical vapor deposition
Authors: Rayar M. , Supiot P. , Veis P. , Gicquel A.
Published: August 2008

Standard H2∕CH4∕B2H6 plasmas (99% of H2 and 1% of CH4, with 0–100ppm of B2H6 added) used for doped diamond film growth are studied by optical emission spectroscopy in order to gain a better understanding of the influence of boron species on the gas phase chemistry. Only two boron species are detected under our experimental conditions (9∕15∕23Wcm−3 average microwave power density values), and the emission spectra used for studies reported here are B(S1∕22−P1∕2,3∕202) and BH[AΠ1-XΣ+1(0,0)]. Variations of their respective emission intensities as a function of the ratio B∕C, the boron to carbon ratio in the gas mixture, are reported. We confirmed that the plasma parameters (Tg, Te, and ne) are not affected by the introduction of diborane, and the number densities of B atoms and BH radical species were estimated from experimental measurements. The results are compared to those obtained from a zero-dimensional chemical kinetic model where two groups of reactions are considered: (1) BHx+H↔BHx−1+H2 (x=1–3) by analogy with the well-known equilibrium CHx+H set of reactions, which occurs, in particular, in diamond deposition reactors; and (2) from conventional organic chemistry, the set of reactions involving boron species: BHx+C2H2 (x=0–1). The results clearly show that the model based on hydrogen and boron hydrides reactions alone is not consistent with the experimental results, while it is so when taking into account both sets of reactions. Once an upper limit for the boron species number densities has been estimated, axial profiles are calculated on the basis of the plasma model results obtained previously in Laboratoire d’Ingénierie des Matériaux et des Hautes Pressions, and significant differences in trends for different boron species are found. At the plasma-to-substrate boundary, [BH] and [B] drop off in contrast to [BH2], which shows little decrease, and [BH3], which shows little increase, in this region.
A surface plasmon laser
Authors: Kumar Pawan , Tripathi V. K. , Liu C. S.
Published: August 2008

We examine the possibility of stimulated emission of a surface plasma wave (SPW) on a metal-vacuum interface by electron-hole recombination in a forward biased p-n junction located near the interface. We consider a thin layer of n-type semiconductor sandwiched between a metal and a p-type semiconductor, and the p-n junction is forward biased. The mode structure of the SPW, propagating along the metal surface, extends up to the p-n junction, where it induces electron-hole recombination and gets amplified. The optical gain of the SPW laser can be made comparable to that of a diode laser by reducing the thickness of the sandwich layer.
Nanoscale amorphization at disclination quadrupoles in deformed nanomaterials and polycrystals
Authors: Bobylev S. V. , Ovid’ko I. A.
Published: August 2008

Special micromechanism of nanoscale amorphization (crystal-to-glass transition in nanoscale regions) in deformed nano- and polycrystalline materials is suggested and theoretically described. The nanoscale amorphization occurs through transformation of disclination quadrupoles generated during plastic deformation. It is shown that the nanoscale amorphization at disclination quadrupoles is energetically favorable in nano- and polycrystalline Si and Si3N4 deformed at high applied stresses in certain ranges of their structural parameters.
Thermal properties of guest-free Si136 and Ge136 clathrates: A first-principles study
Authors: Biswas Koushik , Myles Charles W. , Sanati Mahdi , Nolas G. S.
Published: August 2008

We have used the generalized gradient approximation (GGA) to density functional theory to study the vibrational and thermal properties of guest-free Si136 and Ge136 clathrates. In order to study the effects of supercell size on our results, we have performed both 34 and 136 atom supercell calculations for each material. We find that the 34 atom supercell calculations predict a small frequency downshift (in comparison with the 136 atom supercell calculations) in the vibrational density of states of both materials. The GGA-predicted Γ phonon frequency of Si136 (480 cm−1 at T=0 K) obtained from the 136 atom calculations is in very good agreement with the experimental value for Na1Si136 (484 cm−1 at T=300 K). Using the results from our 136 atom calculations, we have also calculated the temperature dependence of the vibrational contributions to the Helmholtz free energy, the entropy, and the specific heat (CV) of the guest-free Si136 and Ge136 clathrates. The predicted and experimental heat capacities of Si136 are found to be in close agreement.
Optimization of augmentation functions for correlated calculations of spin-spin coupling constants and related properties
Authors: Benedikt Udo , Auer Alexander A. , Jensen Frank
Published: August 2008

A new hierarchy of augmented basis sets optimized for the calculation of molecular properties such as indirect spin-spin coupling constants is presented. Based on the Dunning hierarchy of cc-pVXZ (X=D, T, Q, and 5) basis sets augmentation functions with tight exponents have been optimized for coupled-cluster calculations of indirect spin-spin coupling constants. The optimal exponents for these tight functions have been obtained by optimizing the sum of the absolute values of all contributions to the coupling constant. On the basis of a series of test cases (CO, HF, N2, F2, H2O, NH3, and CH4) we propose a set of tight s, p, and d functions to be added to the uncontracted Dunning basis sets, and, subsequently, to recontract. The resulting ccJ-pVXZ (X=D, T, Q, and 5) basis sets demonstrate excellent cost efficiency in benchmark calculations. These new basis sets should generally be applicable for the calculation of spin-spin coupling constants and other properties that have a strong dependence on powers of 1∕r or even contain a delta distribution for correlated ab initio methods.
Manganese oxide nanoparticles in SrTiO3:Mn
Authors: Badalyan A. G. , Syrnikov P. P. , Azzoni C. B. , Galinetto P. , Mozzati M. C. , Rosa J. , Trepakov V. A. , Jastrabik L.
Published: August 2008

Weakly concentrated “as-grown” and reduced SrTiO3:Mn crystals and ceramics are investigated by means of electron paramagnetic resonance (EPR) to get new insights concerning the Mn substitution in the strontium titanate structure. The temperature dependence of Mn2+ and Mn4+ EPR spectra strongly indicates the formation of MnO2 or MnO small particles to be the favored configuration for the Mn insertion in SrTiO3. Only a part of manganese ions incorporates into the crystal lattice in B position as Mn4+ ions.
Design of one-dimensional photonic crystals using combination of band diagram and photonic gap map approaches
Authors: Tolmachev V. A. , Perova T. S. , Ruttle J. , Khokhlova E. V.
Published: August 2008

The design of one-dimensional photonic crystals and the analysis of their optical properties have been performed using band diagram and forbidden gap map methods. It has been shown that the latter method is more useful for practical applications since (i) it can be applied for any number of periods and (ii) it is more suitable for the selection of a filling fraction in a wide range of values using a single graphical presentation. Three different types of photonic crystals with small, medium, and high optical contrast were modeled using both methods. The features of the omnidirectional band gap formation for photonic crystals with small optical contrast and low number of periods have been explained. The formation of a one-dimensional photonic structure with limited number of periods and omnidirectional band gap close to that for an infinite periodic structure has been discussed.
Experimental evaluation of wetting dynamics models for Sn63Pb37 and SnAg4.0Cu0.5 solder materials
Authors: Kim Chunho , Kang Suk Chae , Baldwin Daniel F.
Published: August 2008

The paper evaluates four of the well-known wetting dynamics models for their applicability to eutectic solder (Sn63Pb37) and lead-free solder (SnAg4.0Cu0.5) that are being used widely as interconnect media in electronics manufacturing. The wetting dynamics models evaluated are the viscous dissipation-limited model, the molecular kinetic model, the chemical reaction-limited model, and the diffusion-limited model. Each of the wetting dynamics models is assessed by the ability to fit the experimental measurements of wetting angle over time of solder ball with several different settings of wetting temperatures and substrate surface finish. The viscous dissipation-limited model fits the experimental measurements relatively well and clearly shows the dependency of the wetting speed on the contact angle. However, the fitted parameters are beyond the physically meaningful range. The molecular kinetic model is very sensitive to contact angle and deviates from the experimental measurements. However, the effects of surface tension imbalance and temperature on the solder wetting dynamics are clearly explained by this model. The chemical reaction-limited model does not match the experimental wetting dynamics well. However, it has an ability to explain the temperature dependence of solder wetting. The more recent version of the chemical reaction-limited model fits the experimental measurements better by the new feature added to explain nonlinearity in wetting speed at high contact angles. The diffusion-limited model predicts the solder wetting dynamics relatively better than the other models. However, the model dictates zero equilibrium angle, contrary to nonzero equilibrium contact angles in reality. It creates deviations from the experimental results, in particular, in the “strict linear spreading” zones where the contact angle approaches the equilibrium contact angle with a constant low speed. The paper discusses the limitations that the wetting dynamics models would have when applied to the eutectic and lead-free solder materials and considerations to be taken into for modeling solder wetting dynamics.
Vlasov simulation of Langmuir decay instability
Authors: Umeda Takayuki , Ito Tetsuya
Published: August 2008

A parametric decay process of beam-generated Langmuir waves is examined by a one-dimensional Vlasov code simulation in the open system. It is confirmed that pump Langmuir waves decay into backscattered Langmuir and ion acoustic waves when the wave energy is higher than the thermal energy of background electrons. In the present Vlasov simulation, a large-amplitude pump Langmuir wave is excited by an electron beam. Then a backscattered Langmuir wave and a forward ion acoustic wave are excited by the parametric decay instability. When the wave energy of the backscattered Langmuir waves is also higher than the thermal energy of background electrons, backward ion acoustic waves are also excited. As a result, the wavenumber spectra of Langmuir and ion acoustic waves are broadened in both forward and backward directions, suggesting possible multiple parametric decay processes of Langmuir waves in a beam-plasma system.
Oligo(vinylidene fluoride) Langmuir-Blodgett films studied by spectroscopic ellipsometry and the density functional theory
Authors: Korlacki R. , Johnson J. Travis , Kim Jihee , Ducharme Stephen , Thompson Daniel W. , Fridkin V. M. , Ge Zhongxin , Takacs James M.
Published: August 2008

Thin films of amphiphilic vinylidene fluoride oligomers prepared by Langmuir–Blodgett deposition on silicone substrates were investigated by comparing experimental and theoretical mid-infrared (IR) spectra. The experimental spectra were obtained using infrared spectroscopic ellipsometry. Theoretical spectra were calculated using density functional theory. Excellent correspondence of major IR bands in both data sets shows that the molecular backbone is oriented with the long axis normal to the substrate plane. This is in contrast to poly(vinylidene fluoride) LB films, in which the polymer chains are parallel to the substrate.
Study of spatial correlations in a supercooled molecular system
Authors: Palomar Ricardo , Sesé Gemma
Published: August 2008

Spatial heterogeneities have been investigated in a supercooled system composed of diatomic molecules with an associated dipole moment by using the molecular dynamics simulation technique. Pair distribution functions of molecules with different mobilities have been evaluated, and it has been found that molecules belonging to the same dynamic domain are spatially correlated. Molecules with extremely large mobilities form larger clusters than those resulting from random statistics. These clusters are stringlike shaped. The mean cluster size displays a maximum at times between the ballistic and the diffusive regime, approximately at the end of the β-relaxation zone. The value of this maximum increases upon cooling the system. An analogous profile has been observed for the characteristic cluster length when plotted against time. Agreement with Adam–Gibbs predictions has been encountered when considering these clusters as the basic dynamic units of the theory. For the extremely slow molecules, a cluster distribution has also been encountered. These clusters are smaller than the ones composed by fast molecules; they do not have a quasilinear geometry and no maximum is observed for their mean cluster size.
Continuum percolation of long lifespan clusters in a simple fluid
Authors: Pugnaloni Luis A. , Carlevaro Carlos M. , Valluzzi Marcos G. , Vericat Fernando
Published: August 2008

We present results on the percolation loci for chemical clusters and physical clusters of long lifespan. Chemical clusters are defined as sets of particles connected through particle-particle bonds that last for a given time τ. Physical clusters are sets of particles that remain close together at every instant for a given period of time τ. By using molecular dynamics simulations of a Lennard-Jones system we obtain the percolation loci at different values of τ as the lines in the temperature-density plane at which the system presents a spanning cluster in 50% of the configurations. We find that the percolation loci for chemical clusters shifts rapidly toward high densities as τ is increased. For moderate values of τ this line converges to the low-density branch of the liquid-solid coexistence curve. This implies that no stable chemical clusters can be found in the fluid phase. In contrast, the percolation loci for physical clusters tend to a limiting line, as τ tends to infinity, which is far from the liquid-solid transition line.
Developing ab initio quality force fields from condensed phase quantum-mechanics/molecular-mechanics calculations through the adaptive force matching method
Authors: Akin-Ojo Omololu , Song Yang , Wang Feng
Published: August 2008

A new method called adaptive force matching (AFM) has been developed that is capable of producing high quality force fields for condensed phase simulations. This procedure involves the parametrization of force fields to reproduce ab initio forces obtained from condensed phase quantum-mechanics/molecular-mechanics (QM/MM) calculations. During the procedure, the MM part of the QM/MM is iteratively improved so as to approach ab initio quality. In this work, the AFM method has been tested to parametrize force fields for liquid water so that the resulting force fields reproduce forces calculated using the ab initio MP2 and the Kohn–Sham density functional theory with the Becke–Lee–Yang–Parr (BLYP) and Becke three-parameter LYP (B3LYP) exchange correlation functionals. The AFM force fields generated in this work are very simple to evaluate and are supported by most molecular dynamics (MD) codes. At the same time, the quality of the forces predicted by the AFM force fields rivals that of very expensive ab initio calculations and are found to successfully reproduce many experimental properties. The site-site radial distribution functions (RDFs) obtained from MD simulations using the force field generated from the BLYP functional through AFM compare favorably with the previously published RDFs from Car–Parrinello MD simulations with the same functional. Technical aspects of AFM such as the optimal QM cluster size, optimal basis set, and optimal QM method to be used with the AFM procedure are discussed in this paper.
In-plane orientation of hcp-Co nanograins on grooved substrate in hard disk media
Authors: Sato Kenji , Maekawa Yuki , Mizoguchi Tadashi , Ogawa Hiroshi , Ikeshoji Tamio
Published: August 2008

It is confirmed by molecular dynamics calculation that dislocations to accommodate the mismatch between hcp-Co alloy nanograins sitting on adjacent slopes of grooves on textured magnetic recording hard disk media induce the preferred in-plane crystalline orientation.
In situ reflection high energy electron diffraction study of dehydrogenation process of Pd coated Mg nanoblades
Authors: Tang F. , Yuan W. , Lu T.-M. , Wang G.-C.
Published: August 2008

The near surface structural evolution in dehydrogenation process of air exposed Pd coated Mg nanoblades was characterized in situ from room temperature to ∼573 K using reflection high energy electron diffraction (RHEED). The evolved normalized diffraction intensity and the full width at half maximum of diffraction peaks have been correlated with the growth of crystal and the change in crystal size, respectively. With RHEED, we are able to detect crystal sizes smaller than ∼2 nm. At room temperature the dominant structures near surface were Pd and MgH2. With the substrate heating MgH2 started to gradually decompose at ∼380 K. When the temperature increased to ∼480 K MgH2 was nearly depleted and Mg6Pd alloys started to form. In addition, at high temperatures pure Mg reappeared and MgO was enhanced significantly even in high vacuum condition. We have discussed the effect of Mg oxide on the dehydrogenation process and the alloy formation between Pd and Mg as well as the accompanying migration of Mg to the surface at high temperatures. Based on our experimental results the structures and compositions that limit the hydrogenation/dehydrogenation cycle of Pd coated Mg nanoblades are suggested. Our findings can help the design of future recyclable hydrogen storage materials.
Frequency dependent dielectric properties of Cu0.5Tl0.5Ba2Ca2Cu3−yZnyO10−δ (y=, 1.0, 1.5,2.0, 2.5) superconductors
Authors: Khan Nawazish A. , Mumtaz M. , Khurram A. A.
Published: August 2008

We have studied the dielectric properties of Cu0.5Tl0.5Ba2Ca2Cu3−yZnyO10−δ (y=0, 1.0, 1.5, 2.0, 2.5) superconductors to investigate the effects of Zn atoms and specifically their role in modifying dielectric properties, such as dielectric loss (tan δ) and ac-conductivity (σac). These dielectric properties have been investigated in the normal state of the samples at room temperature and in their superconducting state. From these analyses, we have determined the excess conductivity in the superconducting state (lower energy state) of the system and suggested its possible role in the mechanism of superconductivity. The lower thermal agitation at 79 K may enhance the polarizability of atoms and hence their dielectric constants (ε′, ε″). A comparison with the dielectric properties of Tl2Ba2Ca2Cu2Ox has shown that our Cu0.5Tl0.5Ba2Ca2Cu3−yZnyO10−δ material has lower losses and higher ac-conductivity at 290 and 79 K. The decreased dielectric loss with increased Zn doping strongly suggested that the polarization is most likely arising due to the separation of charges between Cu0.5Tl0.5Ba2O4−δ charge reservoir layer and mobile carriers in the conducting CuO2/ZnO2 planes since the charge reservoir layer has localized charges at Ba+2, Tl+3, and Cu+2 sites, whereas CuO2/ZnO2 planes contain mobile charge carriers, which are displaced from their equilibrium position by an external frequency. A possibility of the use of this material in practical applications is also discussed.
Solution-processed small molecule-based blue light-emitting diodes using conjugated polyelectrolytes as electron injection layers
Authors: Walker Bright , Tamayo Arnold , Yang Jihua , Brzezinski Jacek Z. , Nguyen Thuc-Quyen
Published: August 2008

Organic blue light-emitting diodes were studied using the solution processable small molecule 2,7-dipyrenyl-9,9′-dioctyl-fluorene (DPF) as the light-emitting material. The devices were fabricated in two simple structures: indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS)/DPF/LiF∕Al and ITO/PEDOT:PSS/DPF/PFN-BIm4∕Al, where PFN-BIm4 is poly[9,9′-bis[6″-(N,N,N-trimethylammonium)hexyl]fluorene-alt-co-phenylene] with tetrakis(imidazolyl)borate counterions. The LiF or PFN-BIm4 act as electron injection layers. The ITO/PEDOT:PSS/DPF/PFN-BIm4∕Al device, in which all organic layers are cast from solution, has a turn-on voltage of 3.8V, a luminance of 2000cd∕m2, and an efficiency of 0.6cd∕A. Using the PFN-BIm4 layer shows a significant improvement of the device performance when compared to the LiF layer.
Steady axisymmetric flow in an enclosed conical frustum chamber with a rotating bottom wall
Authors: Yu Peng , Zeng Yan , Lee Thong See , Low Hong Tong
Published: August 2008

The swirling flow in an enclosed conical frustum chamber with a rotating bottom wall was studied by a numerical model based on the steady, axisymmetric Navier–Stokes equations. The flow behavior was investigated over a wide range of parameters, that is, the Reynolds number up to 2500, the aspect ratio up to 3.5, and the slope angle of the sidewall from 60° to 180°. The vortex breakdown boundary curves were summarized. It was found that vortex breakdown is delayed or even suppressed in the convergent chamber (chamber section narrowing upward). However, for the divergent chamber, the onset of vortex breakdown is precipitated by an initial increase in the slope angle while delayed by a further increase in the slope angle. The flow separation along the inclined sidewall may occur in the divergent chamber with a big slope angle. For an even bigger slope angle, this separation bubble directly combined with the corner vortex at the upper right corner, forming a large recirculation region. The present results suggested that, although vortex breakdown can occur in the divergent chamber with any slope angle, it cannot occur in a convergent chamber with a small slope angle as well as in a conical chamber.
Interactions between polymer brushes in solvents of variable quality: A density functional theory study
Authors: Egorov S. A.
Published: August 2008

We present a density functional theory study of interactions between sterically stabilized colloidal particles in solvents of variable quality. Both flat and spherical polymer brushes are considered, as well as both monatomic and polymeric solvents. It is shown that the interaction between sterically stabilized particles can be tuned from repulsive to attractive by varying the solvent quality, the relative length of free and grafted chains, and by employing a mixed brush consisting of both well and poorly solvated chains.
Bulletlike light pulses in photonic crystals
Authors: Zhou Chuanhong , Gong Qian , Yao Peijun , Zhao Deyin , Jiang Xunya
Published: August 2008

We report the bulletlike propagation of light pulse in a particularly designed two-dimensional (2D) photonic crystal. Unlike traditional light bullet supported by nonlinear materials, this bulletlike propagation is achieved only by 2D photonic crystal, where the diffraction and the group velocity dispersion of a light pulse are eliminated naturally by combining two distinct properties of photonic crystal, i.e., self-collimation and zero group velocity dispersion. Moreover, we studied the influence of third order dispersion on the propagation of light bullet and found that it can be greatly suppressed by an improved structure of photonic crystal.
Understanding the operation of light-emitting electrochemical cells
Authors: Fang Junfeng , Yang Yali , Edman Ludvig
Published: August 2008

The ionic concentration (cion) is demonstrated to play a critical role for the operation of wide-gap light-emitting electrochemical cells. p-type and n-type doped regions are observed to grow from the anode and cathode, respectively, and form a light-emitting p-n junction when cion≥0.1 ions/conjugated-polymer repeat unit. For lower cion, the doped regions come to a full stop before making contact and forming a p-n junction due to an ion-depletion effect. Finally, the n-type doped polymer is observed to be unstable over time under inert conditions, suggesting that a chemical side reaction between the n-type doped polymer and the electrolyte takes place.
Noble gas retention in the target during rotating cylindrical magnetron sputtering
Authors: Mahieu S. , Leroy W. P. , Depla D. , Schreiber S. , Möller W.
Published: August 2008

A rotating cylindrical magnetron with a Ti target was sputtered in pure Xe or in a mixture of Xe and N2. The atomic composition of the target surface during sputtering has been investigated by in situ Rutherford backscattering spectrometry. The noble gas atomic ratio at the target surface is around 3.4% or 9.8% for sputtering in pure Xe and with 10% N2 addition, respectively. Energy resolved mass spectrometry reveals that some of the implanted Xe atoms are sputtered from the target. A radiation enhanced diffusion/detrapping/sputtering mechanism is proposed to model the flux of noble gas leaving the target during sputtering.
The use of hollows and dreys by the common ringtail possum (Pseudocheirus peregrinus) in different vegetation types
Authors: Lindenmayer David B. , MacGregor Christopher , Welsh Alan , Donnelly Christine F. , Brown Darren
Published: August 2008

Tree hollows are a key habitat component for a large number of Australian vertebrates and understanding how these resources are used is critical for developing successful management and conservation strategies for particular species or sets of species. Some hollow-using vertebrates are capable of using other kinds of nest sites. The common ringtail possum (Pseudocheirus peregrinus) is one of these species and it is known to use tree hollows and also to construct nests (dreys) made from sticks and leaves. Nest site selection by P. peregrinus may be a function of hollow availability. This proposition and several related questions were tested in a radio-tracking study that examined patterns of tree hollow and drey use by P. peregrinus in a range of vegetation types in Booderee National Park in Jervis Bay Territory. In addition, this study explored whether hollow and drey use was influenced by a wildfire that occurred in the study region in late 2003. It was found that use of hollows or dreys appeared to be a function of the availability of these resources. Most individuals were either primarily hollow users or primarily drey users. These patterns conformed to differences we recorded in hollow abundance between vegetation types: drey use was most pronounced in shrubland where hollows were rare and hollow use was most prevalent in forest where hollows were abundant. We found no evidence to suggest that hollow or drey use was influenced by fire. There was a trend pattern in our data suggesting that home-range size of P. peregrinus was larger in burnt versus unburnt sites but this effect was not statistically significant. Evidence was found that P. peregrinus selected particular kinds of trees as nest sites. Hollows in dead trees were more often used than those in living trees. Smaller dreys were most likely to be used. Several kinds of nest-selection effects that were contrary to the findings of studies of other arboreal marsupials were identified. These included more frequent use of smaller diameter trees with fewer cavities. The reasons for these unexpected results remain unclear. Findings such as those quantifying gender differences in the frequency of drey use, as well as marked between-vegetation-type differences in nest-type selection, indicate that nest use and nesting behaviour in P. peregrinus may be more complex than previously recognised. These findings also indicate that a deep understanding of the nesting biology of a species may require careful studies of both sexes, across a range of environments, and where disturbances have and have not occurred.
Cloning of genes involved in chromosomal translocations by high-resolution single nucleotide polymorphism genomic microarray
Authors: Kawamata Norihiko , Ogawa Seishi , Zimmermann Martin , Niebuhr Birte , Stocking Carol , Sanada Masashi , Hemminki Kari , Yamatomo Go , Nannya Yasuhito , Koehler Rolf , Flohr Thomas , Miller Carl W. , Harbott Jochen , Ludwig Wolf-Dieter , Stanulla Martin , Schrappe Martin , Bartram Claus R. , Koeffler H. Phillip
Published: August 2008

High-resolution single nucleotide polymorphism genomic microarray (SNP-chip) is a useful tool to define gene dosage levels over the whole genome, allowing precise detection of deletions and duplications/amplifications of chromosomes in cancer cells. We found that this new technology can also identify breakpoints of chromosomes involved in unbalanced translocations, leading to identification of fusion genes. Using this technique, we found that thePAX5gene was rearranged to a variety of partner genes includingETV6,FOXP1,AUTS2, andC20orf112in pediatric acute lymphoblastic leukemia (ALL). The 3′ end of thePAX5gene was replaced by the partner gene. The PAX5 fusion products bound to PAX5 recognition sequences as strongly as wild-type PAX5 and suppressed its transcriptional activity in a dominant-negative fashion. In human B cell leukemia cells, binding of wild-type PAX5 to a regulatory region ofBLK, one of the direct downstream target genes of PAX5, was diminished by expression of the PAX5-fusion protein, leading to repression ofBLK. Expression of PAX5-fusion genes in murine bone marrow cells blocked development of mature B cells. PAX5-fusion proteins may contribute to leukemogenesis by blocking differentiation of hematopoietic cells into mature B cells. SNP-chip is a powerful tool to identify fusion genes in human cancers.
Expressions of uncertainty in candidate knowledge-rich contexts
Authors: Marshman Elizabeth
Published: August 2008

In the widely bi- and multilingual context of work in terminology and terminography today, and with the increasing volume of text-based resources available for carrying out this work, there is a need for computer tools to assist terminologists and terminographers in their tasks — including knowledge acquisition, conceptual description, creation of concept systems, formulation of definitions, and establishment of equivalence between terms — in two or more languages. Conceptual relations may be very useful for all of these applications. One method of semi-automatically locating information about conceptual relations uses knowledge patterns, i.e., linguistic markers of relations that can be used to find segments of text that convey this information. However, this kind of approach faces a number of serious challenges, including that of evaluating the certainty and thus ultimate usefulness of the information identified. Moreover, to date little research has been carried out to evaluate whether knowledge-pattern-based approaches may be expected to encounter comparable phenomena with similar frequency in different languages. This article will explore expressions of uncertainty observed in occurrences of English and French knowledge patterns identifying conceptual relations of ASSOCIATION and CAUSE–EFFECT, and how these may differ in the two languages.
Does single embryo transfer improve the obstetric and neonatal outcome of singleton pregnancy?
Authors: POIKKEUS PIIA , TIITINEN AILA
Published: August 2008

Singleton pregnancies following in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) are associated with increased risks of abnormal placentation, pre‐eclampsia and preterm birth. These risks might partly be a consequence of the number of transferred embryos. In this commentary we summarize the results of three observational studies and one randomized study with 1052 pregnancies following single embryo transfer (SET).

An increased age‐ and parity‐adjusted risk of gestational hypertension and placenta previa in the SET pregnancies as compared to the spontaneously conceiving controls was reported in one of the studies. Preterm births occurred in 6–12% of SET pregnancies and 4–6% of the newborns were of low birth weight (LBW). The frequency of preterm birth and LBW after SET were considered either lower than or similar to those after double embryo transfer (DET) but higher than after spontaneous conception.

Comparison of SET and DET pregnancies thus shows heterogeneous results. Still, it seems that not even a transfer of one good‐quality embryo at a time diminishes all the previously identified increased risks of certain obstetric complications and preterm births in singleton pregnancies following IVF or ICSI.