bluuebunny/crossref_metadata_2025 huggingface dataset:
Placental stem cell markers in pre‐eclampsia
Authors: Benian Ali , Uzun Hafize , Aydın Seval , Albayrak Mustafa , Uludağ Seyfettin , Madazli Riza
Published: November 2007

Objective

To investigate the placental CD34, CD44, and leukemia inhibitory factor (LIF) levels in normotensive and pre‐eclamptic women.

Method

The study population consisted of 21 women with pre‐eclampsia. Twenty normotensive pregnant women served as controls and were matched to pre‐eclamptic patients by gestational age at delivery. Decidual samples obtained from the central part of the placenta were stored at − 70 °C until analysis. CD44 and LIF were quantified in homogenates by enzyme‐linked immunosorbent assay (ELISA), while CD34 was quantified by flow cytometry.

Results

The pre‐eclamptic and normotensive groups were well matched. There were no significant differences in age, parity, weight, and gestational age at birth between the groups (P > 0.05). The mean placental levels of CD34 (6.55 ± 2.48 vs 3.16 ± 1.23), CD44 (385.24 ± 178.85 vs 157.75 ± 31.73, and LIF (140 ± 51.11 vs 96.25 ± 31.62) were significantly higher in pre‐eclamptic compared with normotensive women, respectively (P < 0.05).

Conclusion

Higher levels of CD34, CD44, and LIF were found in the placentas of pre‐eclamptic compared with normotensive women.
Effect of a lower‐dose cetrorelix acetate protocol on in‐vitro fertilization outcome
Authors: Tzeng Chii‐Ruey , Chen Heng‐Ju , Lin Yu‐Hung , Hsieh Bih‐Chwen , Huang Lee‐Wen , Hwang Jiann‐Loung
Published: November 2007

Objective:

To determine whether a low initial dosage of cetrorelix acetate could prevent a premature luteinizing hormone (LH) surge in women undergoing controlled ovarian stimulation.

Method:

Treatment with a recombinant follicle stimulating hormone was started on Day 3 of the menstrual cycle, and 0.125 mg of cetrorelix was injected daily from Day 5 of the ovarian stimulation until the diameter of the dominant follicle reached at least 16 mm. The dosage was then doubled and maintained at 0.250 mg/day until the day before the injection of human chorionic gonadotropin.

Result:

There was a significant decrease in serum LH concentration 1 day after doubling the cetrorelix dosage, and the LH concentration remained low during the follicular phase. Clinical pregnancy occurred in 18 women (42.8%), with 2 intrauterine fetal deaths before the 12th week.

Conclusion:

Increasing the cetrorelix dosage from 0.125 to 0.250 mg/day when the follicular size is appropriate can prevent a premature LH surge.
The Lamfalussy Reform in the EU Securities Markets: Fiduciary Relationships, Policy Effectiveness and Balance of Power
Authors: DE VISSCHER CHRISTIAN , MAISCOCQ OLIVIER , VARONE FRÉEDÉERIC
Published: November 2007

In 2000 a Committee of Wise Men chaired by Alexandre Lamfalussy, former president of the European Monetary Institute was appointed by the Economics and Finance Ministers Council to make recommendations on the regulation of the European securities markets. It proposed a four-level system to improve the legislative process while ensuring what it called a democratic and institutional balance. Our paper questions to what extent the concepts of two basic modes of delegation – agency and trust relationships – are appropriate tools to interpret the new structure set up by the Committee. It formulates hypotheses about its policy effectiveness and the balance of power between Community institutions. Evidence supports the agency hypothesis: the Lamfalussy process has reduced the average time taken to negotiate and adopt the first framework directives at level 1 and it has facilitated the removal of bottlenecks in the process through parallel working at levels 1 and 2. In this sense, delegation has enhanced policy effectiveness in the securities sector. But it is much more difficult to assess the trustee hypothesis: that is, whether the Commission and the Committee of European Securities Regulators (CESR) in fact act as trustees of the member states for the benefit of market actors. For the time being, whether CESR might evolve into a European securities regulator remains an open question.
INTROGRESSIVE HYBRIDIZATION BETWEEN RHODODENDRON KIUSIANUM AND R. KAEMPFERI (ERICACEAE) IN KYUSHU, JAPAN BASED ON CHLOROPLAST DNA MARKERS
Authors: Kobayashi N. , Handa T. , Miyajima I. , Arisumi K. , Takayanagi K.
Published: November 2007

Wild evergreen azalea populations of Rhododendron kiusianum and R. kaempferi (Ericaceae) were analysed using a chloroplast DNA (cpDNA) PCR-RFLP marker that was used to detect introgressive hybridization in our previous study of the Kirishima Mts populations.The populations of the intermediate region in the Unzen Mts, which show phenotypic variation, were demonstrated to result from interspecific hybridization between Rhododendron kiusianum and R. kaempferi, possessing cpDNA from either R. kiusianum (1030/420 bp) or R. kaempferi (950/420/80 bp).Most individuals of Rhododendron kiusianum in the Kujyu Mts, the Aso Mts and the surrounding mountains exhibited the PCR-RFLP pattern of R. kaempferi. These results from the Kujyu Mts and the Aso Mts indicate that natural hybridization and cytoplasmic introgression from Rhododendron kaempferi to R. kiusianum have occurred in the relatively distant past. In the case of Mt Yufudake and Mt Haneyama, the Rhododendron kiusianum population retains the effects of natural hybridization with R. kaempferi in the cpDNA as well as in the variation in flower characteristics.All individuals of Rhododendron kiusianum on Mt Onogaradake in the Takakuma Mts exhibit R. kiusianum cpDNA (1030/420 bp), in spite of variation in flower colour.
OBSERVATIONS AND A NEW SPECIES IN THE GENUS PSEUDOPYXIS (RUBIACEAE)
Authors: Chen Tao
Published: November 2007

Specimens of Pseudopyxis Miq. (Rubiaceae) from China and Japan were studied and compared. As the plants from China differ considerably from those from Japan a new species, Pseudopyxis monilirhizoma T.Chen, is described and a key to Pseudopyxis is presented.
MYCENA LACRIMANS, A RARE SPECIES FROM AMAZONIA, IS BIOLUMINESCENT
Authors: Desjardin D. E. , Braga-Neto R.
Published: November 2007

Mycena lacrimans (Agaricales, Mycenaceae) is redescribed from material collected recently near the type locality and is for the first time reported as bioluminescent. A comprehensive description, illustrations, photographs, comparison with phenetically similar species, and discussion of phylogenetic relationships are provided.
THE IDENTITY OF DISCHIDIA MICHOLITZII (APOCYNACEAE, ASCLEPIADOIDEAE)
Authors: Livshultz T.
Published: November 2007

Dischidia micholitzii N.E.Br. (Apocynaceae, Asclepiadoideae), described from a cultivated plant and erroneously assumed to be from Burma, is native to the Tenimbar and Babar island groups of Maluku, Indonesia. It is closely related to Dischidia ovata Benth. from New Guinea and Australia.
Flora Malesiana, Series I. Volume 17 part 1. C. C. Berg, E. J. H. Corner y &F.M. Jarrett. / Flora Malesiana, Series I. Volume 17 part 2. C. C. Berg & E. J. H. Corner y .
Authors: Weiblen G. D. , Clement W. L.
Published: November 2007

..
Schweregrade der COPD: Die Beurteilung sollte umfassender werden
Authors: Puhan
Published: November 2007

Das klinische Bild und der Verlauf der chronisch-obstruktiven Lungenerkrankung (COPD) sind sehr heterogen. Trotzdem verlässt man sich oft nur auf einen einzigen Parameter, nämlich die Lungenfunktion, um Schweregrad und Verlauf zu beurteilen. Seit längerem ist jedoch erkannt, dass die Lungenfunktion die pulmonalen und extra-pulmonalen Manifestationen der COPD nur ungenügend repräsentiert und eine breitere Beurteilung notwendig ist. Um den Schweregrad der COPD zu beurteilen, sollte die aktuelle Symptomatik erfasst werden, was zumindest die Atemnot und die körperliche Leistungsfähigkeit umfassen sollte. Zudem müssen manchmal die Therapien selber zur Beurteilung des Schweregrads herangezogen werden, weil die Indikationen nicht mehr messbar sind (z.B. Langzeitsauerstoff bei chronischer Hypoxämie). Schliesslich sollten Risikofaktoren für das Fortschreiten der COPD (Rauchen, berufliche und Umweltexpositionen) und für Exazerbationen (Häufigkeit und Schweregrad früherer Exazerbationen, Atemnot, Leistungsfähigkeit und Fähigkeit zum Self-Management) erfasst werden. Mit einer solch breiten Beurteilung könnte das COPD-Management patienten-orientierter werden und dazu beitragen, die symptomatischen und präventiven Therapien besser auf den individuellen Patienten abzustimmen.
Psychogeriatrischer Notfallbesuch
Authors: Wettstein
Published: November 2007

Der Mini-Mental-Status und das Zeichnen einer Uhr sind auch anlässlich eines Hausbesuchs geeignete Instrumente, um bei Verdacht auf Demenz Defizite zu belegen. Mit dem Uhrtest lassen sich v.a. die für die Alltagsbewältigung entscheidenden Exekutivfunktionen untersuchen. Das Errichten einer Beistandschaft ermöglicht es oft, Demenzkranke, die den Alltag nicht mehr richtig bewältigen können, weiterhin zu Hause zu betreuen, da der Beistand die dafür nötige Hilfe organisieren und koordinieren kann.
Theoretical aspects of energetic neutral atoms as messengers from distant plasma sites with emphasis on the heliosphere
Authors: Fahr Hans‐Jörg , Fichtner Horst , Scherer Klaus
Published: November 2007

Ions after a local charge exchange with neutral atoms are not controlled anymore by magnetic or electric fields but instead move as neutral atoms with their instantaneous velocities along free‐flight trajectories, unless they undergo further collisions of elastic or ionizing types. Atoms originating from a charge exchange process of energetic ions, so‐called energetic neutral atoms, can serve as valuable messengers of plasma sites allowing for a remote sensing of distant plasma activities. Remote diagnostics is especially enabled in the case of resonant charge exchange processes at which only charge, but nearly no momentum or energy, is exchanged between collision partners. Most important in this respect and in our context here are charge exchange collisions between protons and hydrogen atoms. In this article we review several theoretical aspects of how this context can be used to study different plasma scenarios like the solar corona and the solar wind, corotating interaction regions, planetary or cometary ionospheres, plasmaspheres or magnetospheres or like the solar wind termination shock, the heliosheath, and the outer heliospheric bow shock. In particular, we address the following questions: Where do energetic atoms play a role, and what kind of role, a dynamic or thermodynamic one, do they play there? From which plasma sites can we expect to receive energetic neutral atom fluxes including even those located far outside these sites? Though we mention in brief presently available and upcoming techniques to measure and to resolve energetic neutral atom fluxes spectrally and spatially, we put the emphasis on theoretical model calculations predicting spectral flux features of energetic neutral atoms with different origins, which in the nearest future may be observed by the NASA Small Explorer mission IBEX and, hopefully, its successors.
Pore geometric modeling for petrophysical interpretation of downhole formation evaluation data
Authors: Gladkikh M. , Jacobi D. , Mendez F.
Published: November 2007

An accurate description of water‐ or oil‐bearing reservoirs strongly depends on a robust determination of their petrophysical parameters, e.g., porosity, permeability and fluid distribution. Downhole logging measurements are the primary means to formation evaluation; however, they do not directly provide the petrophysical properties of interest. To interpret well logging data, a range of empirical models are usually employed. These empirical relationships, however, lack scientific basis and usually represent generalizations of the observed trends. Since macroscopic rock properties vary depending on their microstructure, we suggest using a pore‐scale approach to establish links between various petrophysical properties of sedimentary rocks. We outline a method for computing formation permeability using the proposed rock models. The method utilizes NMR (Nuclear Magnetic Resonance) logging data for the information about porosity and grain size. We also present an approach for prediction of acoustic velocities of model rocks. The proposed methodology is applied to the field data, and the corresponding interpretation results are included in this paper.
Holocene long‐ and short‐term climate changes off Adélie Land, East Antarctica
Authors: Crosta X. , Debret M. , Denis D. , Courty M. A. , Ther O.
Published: November 2007

Diatom data from a marine sediment core give insight on Holocene changes in sea‐surface conditions and climate at high southern latitudes off Adélie Land, East Antarctica. The early to mid‐Holocene was warmer than the late Holocene with a transition at ∼4000 calendar years B. P. Sea ice was less present and spring‐summer growing season was greater during the warm period relative to the cold one, thus limiting sea ice diatom production and favoring more open ocean diatom to develop. The long‐term Holocene climatic evolution in East Antarctica is explained by a combination of a delayed response to local seasonal insolation changes coupled to the long memory of the Southern Ocean. Abrupt variations of the diatom relative abundances, indicating rapid climate changes, are superimposed to the Holocene long‐term trends. Spectral analyses calculate robust frequencies at ∼1600 a (where “a” is years), ∼1250 a, ∼1050 a, ∼570 a, ∼310 a, ∼230 a, ∼150–125 a, ∼110 a, ∼90 a, and ∼66 a. Such periods are very close to solar activity cyclicities, except for the periods at ∼310 a and ∼1250 a, which are close to internal climate variability cyclicities. Wavelet analyses estimate the same periods but indicate nonstationary cyclicities. Rapid climate changes at high southern latitudes may therefore be explained by a combination of external (solar) and internal (thermohaline circulation) forcings.
GPS constraints on vertical crustal motion in the northern Basin and Range
Authors: Bennett Richard A. , Hreinsdóttir Sigrún , Velasco M. Soledad , Fay Noah P.
Published: November 2007

We estimated vertical velocities using an array of 12 continuous GPS stations forming part of the PBO NUCLEUS network. We analyzed data spanning the period 1996 through 2006. The array has an aperture ∼400 km and crosses a major active intracontinental normal fault system in the northern Basin and Range province. The root‐mean‐square (RMS) of vertical rates relative to a local “no net vertical” frame is 0.3 mm/yr, indicating high relative rate precision. The RMS difference between rates based on Δt ≤ 7‐year sub‐strands of the total data set and the full ∼10‐year rate estimates varies as 2.4 Δt−1.3 mm/yr. The net vertical rate observed across the greater Wasatch fault zone is consistent with the predictions of elastic half‐space dislocation models only when the deep slipping part of the fault has very shallow dip (<30°).
Size and volume evaluation of the caldera collapse on Piton de la Fournaise volcano during the April 2007 eruption using ASTER stereo imagery
Authors: Urai Minoru , Geshi Nobuo , Staudacher Thomas
Published: November 2007

The scale of summit collapse during the April 2007 eruption of Piton de la Fournaise volcano, Réunion Island, western Indian Ocean, was evaluated using before‐and‐after differential digital elevation models (DEMs) derived from nadir and backward‐looking images from the Advanced Spaceborne Emission and Reflection radiometer (ASTER) instrument. The dimensions of horizontal length and width, volume and depth of the depression were estimated as 1,100 × 800 m, 9.6 × 107 m3 and 320 m, respectively. These estimates show excellent agreement with field survey data. A ring shaped thermal anomaly (diameter of about 500 m) was found at Dolomieu Crater during or just after the collapse on nighttime ASTER SWIR image. It may correspond to the high temperature areas associated with the cross section of a hydrothermal zone at a constant altitude inside the crater. Our analysis of ASTER orbital data documents topographic and related thermal changes as a result of the 2007 eruption and demonstrates the power of ASTER as a volcanological tool.
Weekly precipitation cycles? Lack of evidence from United States surface stations
Authors: Schultz David M. , Mikkonen Santtu , Laaksonen Ari , Richman Michael B.
Published: November 2007

Previous work has inferred a relationship between human activity and the occurrence and amount of precipitation through examining possible weekly cycles in precipitation. Daily precipitation records for 219 surface observing stations in the United States for the 42‐year period 1951–1992 are investigated for weekly cycles in precipitation. Results indicate that neither the occurrence nor amount of precipitation significantly depends upon the day of the week.
Overpressure and slope stability in prograding clinoforms: Implications for marine morphodynamics
Authors: Wolinsky Matthew A. , Pratson Lincoln F.
Published: November 2007

Rapid deposition of fine‐grained sediments can lead to overpressure buildup along the fronts of prograding sedimentary bodies (clinoforms) ranging from deltas to continental margins. Overpressure reduces shear strength, which can lead to failure of submarine slopes, so that overpressure prediction is potentially of fundamental importance to marine morphodynamics. We generalize one‐dimensional overpressure theory to migrating clinoforms where deposition is highly localized in space and time, and show that overpressure is characterized by a dimensionless loading intensity, the Gibson number (given by the product of sediment supply and slope, divided by sediment hydraulic diffusivity). Our results show that compared to terrestrial slopes, slope stability in overpressured clinoforms is especially sensitive to foreset steepness, which directly affects loading intensity. The utility of our theory is demonstrated by application to modern and ancient clinoforms with documented slope failures. This analysis suggests that (1) most muddy clinoforms will have significant overpressure, (2) many delta fronts and continental margins prograde at a limiting slope threshold for deep‐seated landsliding, and (3) shallow overpressure and near‐surface liquefaction may contribute to mobilization of fluid muds which actively prograde subaqueous deltas. We derive quantitative relationships between sediment supply and slope for clinoforms prograding at limiting equilibrium. Importantly, our results suggest that slope is an inverse function of sediment supply in these systems, implying that commonly used diffusive morphodynamics approaches may be inappropriate.
Interactions between bacterial carbon monoxide and hydrogen consumption and plant development on recent volcanic deposits
Authors: King Gary M , Weber Carolyn F
Published: November 2007

Patterns of microbial colonization and interactions between microbial processes and vascular plants on volcanic deposits have received little attention. Previous reports have shown that atmospheric CO and hydrogen contribute significantly to microbial metabolism on Kilauea volcano (Hawaii) deposits with varied ages and successional development. Relationships between CO oxidation and plant communities were not clear, however, since deposit age and vegetation status covaried. To determine plant–microbe interactions in deposits of uniform ages, CO and hydrogen dynamics have been assayed for unvegetated tephra on a 1959 deposit at Pu’u Puai (PP-bare), at the edge of tree ‘islands’ within the PP deposit (PP-edge) and within PP tree islands (PP-canopy). Similar assays have been conducted for vegetated and unvegetated sites on a 1969 Mauna Ulu (MU) lava flow. Net in situ atmospheric CO uptake was highest at PP-edge and PP-bare sites (2.2±0.5 and 1.3±0.1 mg CO m−2 day−1, respectively), and least for PP-canopy (−3.2±0.9 mg CO m−2 day−1, net emission). Respiration rates, microbial biomass and maximum CO uptake potential showed an opposing pattern. Comparisons of atmospheric CO uptake and CO2 production rates indicate that CO contributes significantly to microbial metabolism in PP-bare and MU-unvegetated sites, but negligibly where vegetation is well developed. Nonetheless, maximum potential CO uptake rates indicate that CO oxidizer populations increase with increasing plant biomass and consume CO actively. Some of these CO oxidizers may contribute to elevated nitrogen fixation rates (acetylene reduction) measured within tree islands, and thus, support plant successional development.
Comparison of lysogeny (prophage induction) in heterotrophic bacterial and Synechococcus populations in the Gulf of Mexico and Mississippi river plume
Authors: Long Amy , McDaniel Lauren D , Mobberley Jennifer , Paul John H
Published: November 2007

Lysogeny has been documented as a fundamental process occurring in natural marine communities of heterotrophic and autotrophic bacteria. Prophage induction has been observed to be prevalent during conditions of low host abundance, but factors controlling the process are poorly understood. A research cruise was undertaken to the Gulf of Mexico during July 2005 to explore environmental factors associated with lysogeny. Ambient physical and microbial parameters were measured and prophage induction experiments were performed in contrasting oligotrophic Gulf and eutrophic Mississippi plume areas. Three of 11 prophage induction experiments in heterotrophic bacteria (27%) demonstrated significant induction in response to Mitomycin C. In contrast, there was significant Synechococcus cyanophage induction in seven of nine experiments (77.8%). A strong negative correlation was observed between lysogeny and log-transformed activity measurements for both heterotrophic and autotrophic populations (r=−0.876, P=0.002 and r=−0.815, P=0.025, respectively), indicating that bacterioplankton with low host growth favor lysogeny. Multivariate statistical analyses indicated that ambient level of viral abundance and productivity were inversely related to heterotrophic prophage induction and both factors combined were most predictive of lysogeny (ρ=0.899, P=0.001). For Synechococcus, low ambient cyanophage abundance was most predictive of lysogeny (ρ=0.862, P=0.005). Abundance and productivity of heterotrophic bacteria was strongly inversely correlated with salinity, while Synechococcus was not. This indicated that heterotrophic bacterial populations were well adapted to the river plume environments, thus providing a possible explanation for differences in prevalence of lysogeny observed between the two populations.
Physiology and genetic traits of reverse osmosis membrane biofilms: a case study with Pseudomonas aeruginosa
Authors: Herzberg Moshe , Elimelech Menachem
Published: November 2007

Biofilm formation of Pseudomonas aeruginosa on the surface of a reverse osmosis (RO) membrane was studied using a synthetic wastewater medium to simulate conditions relevant to reclamation of secondary wastewater effluent. P. aeruginosa biofilm physiology and spatial activity were analyzed following growth on the membrane using a short-life green fluorescent protein derivative expressed in a growth-dependent manner. As a consequence of the limiting carbon source prevailing in the suspended culture of the RO unit, a higher distribution of active cells was observed in the biofilm close to the membrane surface, likely due to the higher nutrient levels induced by concentration polarization effects. The faster growth of the RO-sessile cells compared to the planktonic cells in the RO unit was reflected by the transcriptome of the two cultures analyzed with DNA microarrays. In contrast to the findings recently reported in gene expression studies of P. aeruginosa biofilms, in the RO system, genes related to stress, adaptation, chemotaxis and resistance to antibacterial agents were induced in the planktonic cells. In agreement with the findings of previous P. aeruginosa biofilm studies, motility- and attachment-related genes were repressed in the RO P. aeruginosa biofilm. Supported by the microarray data, an increase in both motility and chemotaxis phenotypes was observed in the suspended cells. The increase in nutrient concentration in close proximity to the membrane is suggested to enhance biofouling by chemotaxis response of the suspended cells and their swimming toward the membrane surface.
Scattering form factors for self-assembled network junctions
Authors: Foster T. , Safran S. A. , Sottmann T. , Strey R.
Published: November 2007

The equilibrium microstructures in microemulsions and other self-assembled systems show complex, connected shapes such as symmetric bicontinuous spongelike structures and asymmetric bicontinuous networks formed by cylinders interconnected at junctions. In microemulsions, these cylinder network microstructures may mediate the structural transition from a spherical or globular phase to the bicontinuous microstructure. To understand the structural and statistical properties of such cylinder network microstructures as measured by scattering experiments, models are needed to extract the real-space structure from the scattering data. In this paper, we calculate the scattering functions appropriate for cylinder network microstructures. We focus on such networks that contain a high density of network junctions that connect the cylindrical elements. In this limit, the network microstructure can be regarded as an assembly of randomly oriented, closed packed network junctions (i.e., the cylinder scattering contributions are neglected). Accordingly, the scattering spectrum of the network microstructure can be calculated as the product of the junction number density, the junction form factor, which describes the scattering from the surface of a single junction, and a structure factor, which describes the local correlations of different junctions due to junction interactions (including their excluded volume). This approach is applied to analyze the scattering data from a bicontinuous microemulsion with equal volumes of water and oil. In a second approach, we included the cylinder scattering contribution in the junction form factor by calculating the scattering intensity of Y junctions to which three rods with spherical cross section are attached. The respective theoretical predictions are compared with results of neutron scattering measurements on a water-in-oil microemulsion with a connected microstructure.
Coriolis coupling effects on the initial-state-resolved dynamics of the N(D2)+H2→NH+H reaction
Authors: Defazio Paolo , Petrongolo Carlo
Published: November 2007

We present Coriolis coupling effects on the initial-state-resolved dynamics of the insertion reaction N(D2)+H2(X̃Σg+1)→NH(X̃Σ−3andãΔ1)+H(S2), without and with nonadiabatic Renner-Teller (RT) interactions between the NH2 X̃B12 and ÃA12 electronic states. We report coupled-channel (CC) Hamiltonian matrix elements, which take into account both Coriolis and RT couplings, use the real wave-packet and flux methods for calculating initial-state-resolved reaction probabilities, and contrast CC with centrifugal-sudden (CS) results. Without RT interactions, Coriolis effects are rather small up to J=40, and the CS approximation can be safely employed for calculating initial-state-resolved, integral cross sections. On the other hand, RT effects are associated with rather large Coriolis couplings, mainly near the linearity of NH2, and the accuracy of the CS approximation thus breaks down at high collision energies, when the reaction starts on the excited ÃA12 surface. We also present the CC-RT distribution of the X̃Σ−3 and ãΔ1 electronic states of the NH products.
Operator-based triple-mode Floquet theory in solid-state NMR
Authors: Scholz Ingo , Meier Beat H. , Ernst Matthias
Published: November 2007

Many solid-state NMR experiments exploit interference effects between time dependencies in the system Hamiltonian to design an effective time-independent Hamiltonian with the desired properties. Effective Hamiltonians can be designed such that they contain only selected parts of the full system Hamiltonian while all other parts are averaged to zero. A general theoretical description of such experiments has to accommodate several time-dependent perturbations with incommensurate frequencies. We describe an extension of the analytical operator-based Floquet description of NMR experiments to situations with three incommensurate frequencies. Experiments with three time dependencies are quite common in solid-state NMR. Examples include experiments which combine magic-angle spinning and radio-frequency irradiation on two nuclei or asynchronous multiple-pulse sequences on a single spin species. The Floquet description is general in the sense that the resulting effective Hamiltonians can be calculated without a detailed knowledge of the spin-system Hamiltonian and can be expressed fully as a function of the Fourier components of the time-dependent Hamiltonian. As a prototype experiment we treat the application of two continuous-wave (cw) radio-frequency fields under magic-angle spinning. Experiments that are included in such a description are Hartmann-Hahn cross polarization or rotary-resonance recoupling experiments with simultaneous cw decoupling.
Doped liquid nitrobenzene is ferroelectric
Authors: Shelton David P. , Quine Zachary
Published: November 2007

The high resolution hyper-Rayleigh light scattering spectrum for liquid nitrobenzene doped with triflic acid (CF3SO3H) shows a narrow spike at zero frequency shift which has the polarization signature of a polar longitudinal collective mode. This spectral spike disappears for pure nitrobenzene. The spectral spike is interpreted as due to ferroelectric domains in the liquid. The dopant molecules appear to induce ferroelectric organization of the nitrobenzene molecules which is otherwise absent in the pure liquid. Estimated domain size is 34nm and relaxation time is 50ns.
Temperature and heat capacity of atomic clusters as estimated in terms of kinetic-energy release of atomic evaporation
Authors: Fujii Mikiya , Takatsuka Kazuo
Published: November 2007

The temperature and heat capacity of isolated atomic clusters are studied in terms of an ab initio statistical theory of kinetic energy distribution by atomic evaporation. Two definitions of canonical temperature are examined and numerically compared: One is based on the most probable kinetic energy release (KER), whereas the other is determined with use of the entire distribution of the KER. The mutual relationship and their advantages are discussed.
Recording simulations on graded media for area densities of up to 1Tbit∕in.2
Authors: Goncharov A. , Schrefl T. , Hrkac G. , Dean J. , Bance S. , Suess D. , Ertl O. , Dorfbauer F. , Fidler J.
Published: November 2007

We report recording simulations on graded media with area densities of 1Tbit∕in.2. The media are composed of a nucleation layer exchange coupled to a hard magnetic storage layer. The nucleation layer has an anisotropy K(z) that gradually varies in order to adjust the domain wall propagation field to the write field. Bits were written with a bit length of 12nm and a track width of 53nm on graded media with total thickness of 21nm and maximum anisotropy of 1MJ∕m3. The computed values for transition jitter are around 0.65nm, depending on the intergrain exchange.
Carrier mobility degradation due to high dose implantation in ultrathin unstrained and strained silicon-on-insulator films
Authors: Dupré C. , Ernst T. , Hartmann J.-M. , Andrieu F. , Barnes J.-P. , Rivallin P. , Faynot O. , Deleonibus S. , Fazzini P. F. , Claverie A. , Cristoloveanu S. , Ghibaudo G. , Cristiano F.
Published: November 2007

Based on electrical measurements and transmission electron microscopy (TEM) imaging, we propose an explanation for the electron and hole mobility degradation with gate length reduction in metal–oxide–semiconductor field effect transistors (MOSFETs). We demonstrate that ion implantation, normally used for source/drain doping, is responsible for transport degradation for short-channel devices. Implantation impact on electrons and holes mobility was investigated both on silicon-on-insulator (SOI) and tensile strained silicon-on-insulator (sSOI) substrates. Wafers with ultrathin Si films (from 8 to 35 nm) were Ge implanted at 3 keV and various concentrations (from 5×1014 to 2×1015 atoms cm−2), then annealed at 600 °C for 1 h. Secondary ion mass spectrometry enabled us to quantify the Ge-implanted atoms concentrations. The end-of-range defects impact on mobility was investigated with the pseudo-MOSFET technique. Measurements showed a mobility decrease as the implantation dose increased. We demonstrated that sSOI mobility is more sensitive to implantation than SOI mobility, without any implantation-induced strain relaxation in sSOI (checked using the ultraviolet Raman technique). A 36% (25%) holes (electrons) mobility degradation was measured for sSOI, while SOI presented a 21% mobility degradation for holes and 5% for electrons. Finally, the electrical results were compared with morphological studies. Plan-view TEM showed the presence of interstitial defects formed during ion implantation and annealing. The defect density was estimated to be two times higher in sSOI than in SOI, which is in full agreement with electrical results mentioned before. The results are relevant for the optimization of the source and drain regions of advanced nanoscale SOI and sSOI transistors.
The collapse of a mixed patch in stratified fluid
Authors: Sutherland Bruce R. , Chow Amenda N. F. , Pittman Tyler P.
Published: November 2007

Lock-release laboratory experiments are performed to examine the collapse of a localized mixed patch of fluid in a uniformly stratified ambient with constant buoyancy frequency, N. The intrusion speed is approximately 0.13NHℓ, in which Hℓ is the depth of the mixed patch. This is consistent with the speed of intrusions released from a full-depth lock where Hℓ=H is the depth of the ambient. The vertically propagating waves have frequency set by N (ω≃0.7N) and the horizontal wavelength, λx, is set by Hℓ (λx≃1.5Hℓ). The amplitude is found to scale as the depth of the mixed region cubed at small Hℓ, and saturates at large Hℓ≳10cm due to nonlinear effects.
A density functional study of the effect of hydrogen on the strength of an epitaxial Ag/ZnO interface
Authors: Lin Zheshuai , Bristowe Paul D.
Published: November 2007

A density functional calculation of a Ag (111)/ZnO (0001) interface with 30° rotated epitaxy reveals that the strength of the interface, as determined from the work of separation, is significantly lowered by the presence of hydrogen. This interface has been observed in magnetron sputtered thin-film systems and could be present in optical multilayers used to coat architectural glass for solar-control and energy efficiency. The weakening of the hydrogen-modified interface, which originates in the Ag-H bond, could partly explain the observed delamination of the interface during processing or service in a hydrogen-rich or humid environment.
Enhanced thermoelectric properties in CoSb3-xTex alloys prepared by mechanical alloying and spark plasma sintering
Authors: Liu Wei-Shu , Zhang Bo-Ping , Li Jing-Feng , Zhang Hai-Long , Zhao Li-Dong
Published: November 2007

CoSb 3 - x Te x ( x = 0.05 − 0.3 ) skutterudite polycrystals with an average grain size of 160 nm were fabricated by mechanical alloying combined with spark plasma sintering. The variation of lattice parameter with Te content indicates that the solution limit of Te was x=0.15, above which the impurity phases of Te, CoTe2, and CoSb2 appeared, and the matrix cracked above 500 °C. All samples behaved as degenerate semiconductors. The forbidden energy gap was estimated to be 0.047 eV from the temperature corresponding to the occurrence of intrinsic excitation, which is in good agreement with Singh’s theoretical calculation (0.05 eV) [D. J. Singh and W. E. Pickett, Phys. Rev. B 50, 11235 (1994)]. The CoSb2.85Te0.15 sample had the highest power factor and the lowest thermal conductivity, resulting in the highest thermoelectric figure of merit, ZT=0.93 at 547 °C. The role of Te substitution in enhancing thermoelectric properties is discussed in relation to the bipolar diffusion mechanism.
Sawtooth control using beam ions accelerated by fast waves in the DIII-D tokamak
Authors: Choi M. , Turnbull A. D. , Chan V. S. , Chu M. S. , Lao L. L. , Jeon Y. M. , Li G. , Ren Q. , Pinsker R. I.
Published: November 2007

The accuracy of the Porcelli sawtooth model is evaluated using realistic numerical calculations for a DIII-D [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] experiment with neutral beam injection and fast wave heating. Simulation results confirm that beam ions accelerated by the fast waves play a crucial role in delaying the normal sawtooth crash and inducing giant sawteeth with large amplitude and long period. A single giant sawtooth period was analyzed in detail in an effort to evaluate the efficacy of the Porcelli model in quantitatively predicting a particular sawtooth crash by evaluating the model through the sawtooth period using equilibria reconstructed from the discharge data. The kinetic stabilizing contribution of fast trapped ions is found to depend strongly on both the experimentally reconstructed magnetic shear at the q=1 surface (s1) and the calculated poloidal beta of trapped beam ions inside the q=1 surface. To within estimates of the error from the equilibrium reconstructions and the simulation fast ion particle statistics, the results are consistent with the observed sawtooth crash. The calculations indicate that the sawtooth crash is ultimately triggered by the resistive kink in the ion-kinetic regime after the stabilizing contribution from the fast ions is reduced due to an increase in s1 as the discharge evolves.
Physical mechanism of effective work function modulation caused by impurity segregation at Ni silicide/SiO2 interfaces
Authors: Tsuchiya Yoshinori , Yoshiki Masahiko , Kinoshita Atsuhiro , Koyama Masato , Koga Junji , Ogawa Masaki , Zaima Shigeaki
Published: November 2007

An effective work function (Φeff) modulation caused by impurity doping in Ni-FUSI/SiO2 systems has been systematically investigated. To clarify the physical origin, we reveal the relationship between changes of Φeff modulation factors at gate electrode interfaces and Φeff modulation ranges (ΔΦeff) in two different doping processes (predoping and post-doping). In the predoping process, in which impurities (As or B) are implanted into polycrystalline Si gate before Ni fully silicided gate formation, both the crystal structure of the Ni silicide layer and the impurity concentration at the Ni silicide/SiO2 interface change depending on the impurity species. On the other hand, the impurity post-doping process, in which impurities are implanted and introduced to the Ni silicide/SiO2 interface after Ni silicide formation, makes it possible to introduce the desired amount of impurities into the interface without any structural change of the Ni silicide. In both cases, dependence of ΔΦeff on interface impurity concentration is almost the same, indicating that impurity segregation is the main cause of Φeff modulation. From the results of hard x-ray photoelectron spectroscopy and back-side x-ray photoelectron spectroscopy, the segregated As atoms, which change Φeff to lower values, are mainly located at the Ni silicide side of the Ni silicide/SiO2 interface. On the contrary, B atoms, which change Φeff to higher values, diffuse into SiO2 and are located at the SiO2 side of the interface. Based on these experimental results, we propose a physical model for Φeff modulation with impurity doping such that the position and concentration of impurity at the interface determine the direction and the extent of Φeff modulation with impurity segregation.
Thermoelectric properties of silicon-germanium type I clathrates
Authors: Martin J. , Nolas G. S. , Wang H. , Yang J.
Published: November 2007

We report the synthesis and chemical, structural, and transport properties characterization of Ba8Ga16SixGe30−x type I clathrates with similar Ga-to-group IV element ratios but with increasing Si substitution (4<x<14). Substitution of 20 at. % Si within the Ga-Ge lattice framework of the type I clathrate Ba8Ga16Ge30 results in thermoelectric performance enhancement. The unique dependences of carrier concentration, electrical resistivity, Seebeck coefficient, and carrier effective mass on Si substitution level, and the lack of variation in the Ga-to-group IV element ratios may imply a modified band structure with Si substitution. These results indicate an additional method for tuning the electronic properties of Ba8Ga16Ge30 for thermoelectric applications.
Metalorganic chemical vapor deposition of InGaN layers on ZnO substrates
Authors: Wang Shen-Jie , Li Nola , Park Eun-Hyun , Lien Siou-Cheng , Feng Zhe Chuan , Valencia Adriana , Nause Jeff , Ferguson Ian
Published: November 2007

InGaN layers have been grown on (0001) ZnO substrates by metalorganic chemical vapor deposition utilizing a low temperature grown thin GaN buffer. Good quality InGaN films with a wide range of In composition were confirmed by high-resolution x-ray diffraction. Even at high indium concentrations no In droplets and phase separation appeared, possibly due to coherent growth of InGaN on ZnO. Photoluminescence showed broad InGaN-related emissions with peak energy lower than the calculated InGaN band gap, possibly due to Zn/O impurities diffused into InGaN from the ZnO substrate. An activation energy of 59 meV for the InGaN epilayer is determined.
Characterization of defects in ZnO nanocrystals: Photoluminescence and positron annihilation spectroscopic studies
Authors: Mishra A. K. , Chaudhuri S. K. , Mukherjee S. , Priyam A. , Saha A. , Das D.
Published: November 2007

Defects present in ZnO nanocrystals prepared by a wet chemical method have been characterized by photoluminescence (PL) and positron annihilation spectroscopy (PAS) techniques. The as-prepared sample was heat treated at different temperatures to obtain nanocrystals in the size range of 19–39nm. X ray diffractograms confirmed the single-phase wurtzite structure formation. Photoluminescence measurements showed a strong violet band at 434nm, which has been identified as due to electronic transitions from the zinc interstitial defect level to the top of the valence band. A marked decrease in the intensity of the violet emission with increasing heat-treatment temperature has been observed, which is attributed to recombination of zinc interstitials with zinc vacancies. Positron annihilation spectroscopy has been employed to understand the dynamics of the vacancy-type defects and their annealing behavior. The observed variation of the defect related lifetime components with heat-treatment temperature has been successfully explained by using a three-state trapping model. The results of PL and PAS studies in the present case are found to be complementary to each other.
Nonlinear current-voltage characteristics measured across circular deoxyribonucleic acid (DNA) molecule bundles
Authors: Romano P. , Polcari A. , Verruso B. , Colantuoni V. , Saldarriaga W. , Baca E.
Published: November 2007

We measured current-voltage characteristics of circular deoxyribonucleic acid (DNA) bundle samples embedded in a water mantle lying on a nylon porous membrane between vacuum-evaporated gold electrodes. The nonlinear behavior observed at room temperature on samples of different molecular sizes and variable concentration was interpreted as a long-range conduction mechanism that takes place by means of charge hopping through the network of molecules. A tunneling process acting as an additional transport channel inside single molecules between energetically appropriate bases was inferred. Our data also suggest at low bias a thermionic emission mechanism by means of which the charges move from one electrode, overcoming a potential barrier. Characteristic energies involved in the transport were reproducibly measured.
Influence of lateral crystallization on gate oxide in polycrystalline silicon thin-film transistors
Authors: Kang Il-Suk , Han Shin-Hee , Joo Seung-Ki
Published: November 2007

The phase transformation in a film influences its surrounding. In order to remove influences on gate oxide caused by metal-induced unilateral crystallization, a gate was formed after a lateral crystallization. The thin-film transistor (TFT) by the novel fabrication method was shown to have a higher current drive and better immunity to early drain breakdown, compared to the conventional TFT performed by a lateral crystallization and a dopant activation process at a time. These improvements are attributed to being free from the interface state generation at the interface between the gate oxide and the active silicon.
Correlation between compositional fluctuation and magnetic properties of Tm-doped AlGaN alloys
Authors: Nepal N. , Bedair S. M. , El-Masry N. A. , Lee D. S. , Steckl A. J. , Zavada J. M.
Published: November 2007

The magnetic properties of Tm-doped AlxGa1−xN (0⩽x⩽1) alloys grown by solid-source molecular beam epitaxy were studied by hysteresis measurements and shown to exhibit ferromagnetic behavior at room temperature. The measured magnetization was strongly dependent on the Al content and reached a maximum for x=0.62. Previously reported photoluminescence measurements on these films yielded a blue emission at 465nm with peak intensity at the same Al content. Both magnetic and optical properties are directly correlated with the alloy compositional fluctuation found in undoped AlxGa1−xN alloys.
Gauge transformations for the constrained CKP and BKP hierarchies
Authors: He Jingsong , Wu Zhiwei , Cheng Yi
Published: November 2007

A special chain of the gauge transformations of the two-component constrained KP is introduced, and then the transformed components and the τ-function of this hierarchy are presented. Based on this, by the different reductions, the gauge transformations of the constrained BKP and the constrained CKP hierarchies are obtained. Furthermore, the transformed component functions and τ-functions of them are expressed by the determinants with the help of the determinant representation of the gauge transformation operators.
Planar photonic crystals infiltrated with nanoparticle/polymer composites
Authors: Tay Savaş , Thomas Jayan , Momeni Babak , Askari Murtaza , Adibi Ali , Hotchkiss Peter J. , Jones Simon C. , Marder Seth R. , Norwood Robert A. , Peyghambarian N.
Published: November 2007

Infiltration of planar two-dimensional silicon photonic crystals with nanocomposites using a simple yet effective melt processing technique is presented. The nanocomposites that were developed by evenly dispersing functionalized TiO2 nanoparticles into a photoconducting polymer were completely filled into photonic crystals with hole sizes ranging from 90to500nm. The infiltrated devices show tuning of the photonic band gap that is controllable by the adjustment of the nanoparticle loading level. These results may be useful in the development of tunable photonic crystal based devices and hybrid light emitting diodes and solor cells.
Influence of silver nanoparticles in the luminescence efficiency of Pr3+-doped tellurite glasses
Authors: Kassab Luciana R. P. , de Araújo Cid B. , Kobayashi Renata A. , de Almeida Pinto Ricardo , da Silva Davinson M.
Published: November 2007

We studied the influence of silver nanoparticles (NPs) in the luminescence properties of TeO2–PbO–GeO2 glass doped with trivalent praseodymium (Pr3+) ions. The experiments were performed with samples containing different concentrations of NPs controlled by heat treatment of the glass. The enhancement of the Stokes luminescence with the increase of the NPs concentration was observed for samples excited at 454nm. The influence of the NPs on the frequency upconversion (anti-Stokes) emissions of Pr3+ under excitation at 520nm was also investigated. In this case, enhancement of the emissions around 460 and 486nm was observed and the excitation pathway is also discussed.