bluuebunny/crossref_metadata_2025 huggingface dataset:
First discovery and formation process of authigenic siderite from gas hydrate–bearing mud volcanoes in fresh water: Lake Baikal, eastern Siberia
Authors: Krylov Alexey , Khlystov Oleg , Zemskaya Tamara , Minami Hirotsugu , Hachikubo Akihiro , Nunokawa Yutaka , Kida Masato , Shoji Hitoshi , Naudts Lieven , Poort Jeffrey , Pogodaeva Tatiana
Published: March 2008

We report on the first authigenic siderite (FeCO3) concretions recovered from near‐bottom sediments at gas hydrate‐bearing mud volcanoes in fresh water (Lake Baikal, Eastern Siberia). The carbonates appear as firm ‘plate‐type’ formations at the Malenky mud volcano (Southern Baikal Basin) and as soft nodules at the K‐2 mud volcano (Central Baikal Basin). Calcium is the main divalent component which substitutes iron in the carbonate lattice (7 to 20 mol%). The δ13C values of the carbonates (+3.3 to +6.8‰ at Malenky, and +16.5 to +21.9‰ PDB at K‐2) indicate that their formation is due to methanogenesis. The latter was most likely caused by the microbial methyl‐type (acetate) fermentation that is suggested from the isotopic composition of the accompanying methane hydrates and dissolved methane. General depletion of the siderites in 18O (−11.6 to −9.9 ‰ at Malenky, and −13.9 to −12.3‰ PDB at K‐2) is mainly inherited from the isotope composition of pore water (−15.2 to −15.4‰ SMOW) at ambient temperature (3.5°C).
Fluvial terrace riser degradation and determination of slip rates on strike‐slip faults: An example from the Kunlun fault, China
Authors: Harkins Nathan , Kirby Eric
Published: March 2008

The use of displaced fluvial terrace risers to determine slip rates along strike‐slip faults depends on knowing when risers become passive markers. Typically, chronologic constraints from terrace deposits only place bounds on this age; consequent slip rates may be highly uncertain. Along the Kunlun fault, in northeastern Tibet, we demonstrate that consideration of riser degradation can augment terrace chronology and improve the precision of slip‐rate estimates. Multiple offset risers and 14C age determinations from terrace treads yield a narrow range of slip rates of 4.5 ± 0.5 m/kyr at one site, but permit a wide range of allowable rates (3–10 m/kyr) in an adjacent drainage. Using a locally calibrated sediment transport rate of 3.2–5.4 m2/ka, we show that riser morphology at this latter site is consistent with degradation since abandonment of the upper terrace tread. Our analysis indicates that slip rates at this site are ∼5 ± 2 m/kyr.
Investigation of the response of equatorial MLTI region during a partial solar eclipse through ground‐based daytime optical technique
Authors: Vineeth C. , Pant Tarun K. , Thampi Smitha V. , Sridharan R. , Ravindran Sudha , Devasia C. V. , Kishore Kumar K. , Alex S.
Published: March 2008

First experimental evidence for solar eclipse induced changes in the equatorial mesopause and the thermosphere ionosphere regions using daytime optical photometer is presented. The photometer was operated in scanning mode to probe the thermosphere and mesopause regions simultaneously in North‐South direction over Trivandrum (8.5°N; 77°E; dip lat. 0.5°N) during a partial solar eclipse event on 03 October 2005. This provided a unique data set of thermosphere and mesopause regions over a horizontal distance of 600 and 240 km respectively from zenith during this event. The striking feature observed during the eclipse is the enhancement in the thermospheric O(1D) 630 nm dayglow intensity and its equatorward movement. Another noteworthy observation is an overall enhancement in the mesopause temperature, more pronounced (∼25–30 K) over zenith. These observations are discussed in context of the vertical coupling of the mesopause with thermosphere‐ionosphere region.
Statistical properties of tail plasma sheet electrons above 40 keV
Authors: Åsnes A. , Friedel R. W. H. , Lavraud B. , Reeves G. D. , Taylor M. G. G. T. , Daly P.
Published: March 2008

We use data from four tail seasons (2001–2004) of the Cluster spacecraft to study statistical features of energetic electrons (40–400 keV) in the magnetotail plasma sheet in combination with plasma parameters and indices of geomagnetic activity. We find that the horizontal magnetic field magnitude best orders the energetic electron observations. Using this method we observe a statistical flux gradient toward the neutral sheet. The fluxes also increase with an increase in the vertical magnetic field component (dipolarization). The intensity of supra‐thermal electrons is observed to increase strongly as function of plasma temperature. Although the energetic electron fluxes also appear to increase strongly with geomagnetic activity this is found to be mainly due to the increase in plasma temperature with increasing Kp. Investigation of neutral sheet fluxes and phase space densities at fixed first adiabatic invariant (μ) indicates that adiabatic heating can explain observed flux increases during field dipolarization. The spectral slope in the supra‐thermal range is observed to be independent of geomagnetic activity (Kp), while there is a significant local time dependence, with harder spectra observed at dawn compared to the dusk side.
3D MHD reconnection model coupled with Cluster multi‐spacecraft data
Authors: Westerberg Lars G. , Åkerstedt Hans O. , Nilsson Hans , Réme Henri , Balogh André
Published: March 2008

We present a model where a three‐dimensional viscous/resistive analytical model of the large scale plasma flow in the outflow region about a reconnection site at the dayside magnetopause, is coupled with multispacecraft measurements from the Cluster satellite armada. A total of ten magnetopause crossings have been analyzed during the period 10:29–11:05 UT 26 January 2001, where nine are shown to be suitable to be coupled with the analytical model. Five of these nine reconnection events results in a successful coupling. By fitting the analytical expressions of the plasma velocity and magnetic field behavior during the transition of the magnetopause, with data from the Cluster spacecraft we obtain estimates of the location of the X‐line together with estimates on the anomalous transport coefficients of kinematic viscosity (ν) and magnetic diffusivity (ηd). We also obtain the development of the magnetopause transition layer away from the X‐line. It is shown that the distance from the spacecraft to the X‐line varies between 0.01 and 1 Earth radii, while ν + ηd have a value between 4 · 104 km2/s and 4 · 106 km2/s. Furthermore it is shown that the transition layer thickness follows the analytical pattern where it grows proportional to the square root of the distance from the reconnection site. The estimated thickness obtained from each spacecraft is shown to follow the analytical structure well.
Two‐phase model for sand transport in sheet flow regime
Authors: Amoudry L. , Hsu T.‐J. , Liu P. L.‐F.
Published: March 2008

We introduce a two‐phase model for sand transport in sheet flow regime. This model uses a collisional theory and a k – ɛ fluid turbulence closure to respectively model the sediment and fluid phase stresses. The sediment stress closure adopts a balance equation of sediment particle fluctuation energy based on kinetic theory that incorporates two‐way interactions between fluid and sediment phases. The fluid turbulence closure also considers the two‐way interaction between fluid turbulence and sand particles. Model‐data comparisons for the sheet layer for oscillatory flows in a U‐tube and for open channel flows demonstrate the model's predictive skill. For steady open channel flows the fluid phase velocity follows closely the law of wall (i.e., the log‐profile) in which the von Karman constant is reduced and the equivalent roughness is increased, compared to the clear fluid flow conditions. The model also provides information in the near‐bed region where the transition from the solid‐like to the fluid‐like behavior of sediment particles is resolved and both the bed load layer thickness and bed load transport rate can be evaluated. For unsteady flows, this model can predict time evolutions for sediment transport throughout the water column.
Whitecapping and wave field evolution in a coastal bay
Authors: Mulligan R. P. , Bowen A. J. , Hay A. E. , van der Westhuysen A. J. , Battjes J. A.
Published: March 2008

Evolution of the wave field in a coastal bay is investigated, by comparison between field observations and numerical simulations using a spectral wave model (Simulating WAves Nearshore (SWAN)). The simulations were conducted for the passage of an extratropical storm, during which surface elevation spectra were bimodal owing to local wind‐sea generation and swell propagation into the bay. SWAN was run in stationary and nonstationary mode for two whitecapping source term formulations. The first was developed by Komen et al. (1984) and is dependent on spectrally averaged wave steepness, and thus includes swell in the calculation of whitecapping dissipation and typically overestimates wind sea in the presence of swell. The second, proposed by van der Westhuysen et al. (2007), estimates whitecapping of wind sea locally in the wave spectrum and is not coupled to swell energy. This formulation reproduced the magnitude and shape of the observed wind‐sea spectral peak much better than the previous formulation. Whitecapping dissipation rates have been estimated from observations, using the equilibrium range theory developed by Phillips (1985), and are well correlated with both wind speed and acoustic backscatter observations. These rates agree with SWAN estimates using the spectrally local expression, and provide additional physical validation for the whitecapping source term.
Remote sources of water vapor forming precipitation on the Norwegian west coast at 60°N–a tale of hurricanes and an atmospheric river
Authors: Stohl A. , Forster C. , Sodemann H.
Published: March 2008

In September 2005, an extreme precipitation event occurred on the Norwegian southwest coast, which produced flooding and landslides and caused considerable infrastructure damage and loss of human life. We found that this event was triggered by the transport of tropical and subtropical moisture associated with two former hurricanes, Maria and Nate, which both underwent transition into extratropical cyclones. The two former hurricanes generated a large stream of (sub)tropical air which extended over more than 40° of latitude and across the North Atlantic Ocean and carried a large amount of moisture originally associated with hurricane Nate; a so‐called atmospheric river or moisture conveyor belt. The mountains along the Norwegian coast caused a strong orographic enhancement of the precipitation associated with the moist air. A Lagrangian moisture tracking algorithm was employed to show that the evaporative source of the precipitation falling over Norway was distributed over large parts of the North Atlantic Ocean, and indeed included large contribution from the subtropics and smaller ones from the tropics. The moisture tracking algorithm was also applied over a 5‐year period. It was found that (sub)tropical sources can contribute substantially to the precipitation falling in southwestern Norway throughout the year. Thus other transport mechanisms than hurricanes are important, too, for moving (sub)tropical moisture so far north. The (sub)tropical moisture source is relatively more important during the positive phase of the North Atlantic Oscillation, as well as for stronger precipitation events.
Predicted change in global secondary organic aerosol concentrations in response to future climate, emissions, and land use change
Authors: Heald C. L. , Henze D. K. , Horowitz L. W. , Feddema J. , Lamarque J.‐F. , Guenther A. , Hess P. G. , Vitt F. , Seinfeld J. H. , Goldstein A. H. , Fung I.
Published: March 2008

The sensitivity of secondary organic aerosol (SOA) concentration to changes in climate and emissions is investigated using a coupled global atmosphere‐land model driven by the year 2100 IPCC A1B scenario predictions. The Community Atmosphere Model (CAM3) is updated with recent laboratory determined yields for SOA formation from monoterpene oxidation, isoprene photooxidation and aromatic photooxidation. Biogenic emissions of isoprene and monoterpenes are simulated interactively using the Model of Emissions of Gases and Aerosols (MEGAN2) within the Community Land Model (CLM3). The global mean SOA burden is predicted to increase by 36% in 2100, primarily the result of rising biogenic and anthropogenic emissions which independently increase the burden by 26% and 7%. The later includes enhanced biogenic SOA formation due to increased emissions of primary organic aerosol (5–25% increases in surface SOA concentrations in 2100). Climate change alone (via temperature, removal rates, and oxidative capacity) does not change the global mean SOA production, but the global burden increases by 6%. The global burden of anthropogenic SOA experiences proportionally more growth than biogenic SOA in 2100 from the net effect of climate and emissions (67% increase predicted). Projected anthropogenic land use change for 2100 (A2) is predicted to reduce the global SOA burden by 14%, largely the result of cropland expansion. South America is the largest global source region for SOA in the present day and 2100, but Asia experiences the largest relative growth in SOA production by 2100 because of the large predicted increases in Asian anthropogenic aromatic emissions. The projected decrease in global sulfur emissions implies that SOA will contribute a progressively larger fraction of the global aerosol burden.
Remote sensing of the spatial and temporal structure of magnetopause and magnetotail reconnection from the ionosphere
Authors: Chisham G. , Freeman M. P. , Abel G. A. , Lam M. M. , Pinnock M. , Coleman I. J. , Milan S. E. , Lester M. , Bristow W. A. , Greenwald R. A. , Sofko G. J. , Villain J.‐P.
Published: March 2008

Magnetic reconnection is the most significant process that results in the transport of magnetized plasma into and out of the Earth's magnetosphere‐ionosphere system. There is also compelling observational evidence that it plays a major role in the dynamics of the solar corona, and it may also be important for understanding cosmic rays, accretion disks, magnetic dynamos, and star formation. The Earth's magnetosphere and ionosphere are presently the most accessible natural plasma environments where magnetic reconnection and its consequences can be measured, either in situ or by remote sensing. This paper presents a complete methodology for the remote sensing of magnetic reconnection in the magnetosphere from the ionosphere. This method combines measurements of ionospheric plasma convection and the ionospheric footprint of the reconnection separatrix. Techniques for measuring both the ionospheric plasma flow and the location and motion of the reconnection separatrix are reviewed, and the associated assumptions and uncertainties are assessed, using new analyses where required. Application of the overall methodology is demonstrated by the study of a 2‐h interval from 26 December 2000 using a wide range of spacecraft and ground‐based measurements of the Northern Hemisphere ionosphere. This example illustrates how spatial and temporal variations in the reconnection rate, as well as changes in the balance of magnetopause (dayside) and magnetotail (nightside) reconnection, can be routinely monitored, affording new opportunities for understanding the universal reconnection process and its influence on all aspects of space weather.
New analytical derivation of the mean annual water‐energy balance equation
Authors: Yang Hanbo , Yang Dawen , Lei Zhidong , Sun Fubao
Published: March 2008

The coupled water‐energy balance on long‐term time and catchment scales can be expressed as a set of partial differential equations, and these are proven to have a general solution as E/P = F(E0/P, c), where c is a parameter. The state‐space of (P, E0, E) is a set of curved faces in P − E0 − E three‐dimensional space, whose projection into E/P − E0/P two‐dimensional space is a Budyko‐type curve. The analytical solution to the partial differential equations has been obtained as E = E0P/(Pn + E0n)1/n (parameter n representing catchment characteristics) using dimensional analysis and mathematic reasoning, which is different from that found in a previous study. This analytical solution is a useful theoretical tool to evaluate the effect of climate and land use changes on the hydrologic cycle. Mathematical comparisons between the two analytical equations showed that they were approximately equivalent, and their parameters had a perfectly significant linear correlation relationship, while the small difference may be a result of the assumption about derivatives in the previous study.
Why Hell is other People: Distinctively Human Psychological Suffering
Authors: Bering Jesse M.
Published: March 2008

Just as there is remarkable continuity between the structures, abilities, and behaviors of closely related species, so too are there equally remarkable differences. Because only our species has evolved the social cognitive mechanisms that enable a heightened sensitivity to the minds of others, only our species suffers the psychological consequences. Using Sartre's famous play No Exit to illuminate the interplay between evolved psychology and social conscious experience, I show how theory of mind is both biologically adaptive and the common denominator in distinctively human types of psychological suffering.
Scientific Talent, Training, and Performance: Intellect, Personality, and Genetic Endowment
Authors: Simonton Dean Keith
Published: March 2008

Despite over a century of research, psychologists have still not established scientific talent as an empirically demonstrable phenomenon. To help solve this problem, a talent definition was first proposed that provided the basis for three quantitative estimators of criterion heritability that can be applied to meta-analytic and behavior genetic research concerning the intellectual and personality predictors of scientific training and performance. After specifying the ideal data requirements for the application of the three estimators, the procedures were applied to previously published results. Personality traits were illustrated with the use of the California Psychological Inventory and the Eysenck Personality Questionnaire with respect to two criteria (scientists versus nonscientists and creative scientists versus less creative scientists) and intellectual traits with the use of the Miller Analogies Test with respect to seven criteria (graduate grade-point average, faculty ratings, comprehensive examination scores, degree attainment, research productivity, etc.). The outcome provides approximate, lower-bound estimates of the genetic contribution to scientific training and performance. Subsequent discussion concerns what future research is necessary for a more complete understanding of scientific talent as an empirical phenomenon.
Why Do Men Rape? An Evolutionary Psychological Perspective
Authors: McKibbin William F. , Shackelford Todd K. , Goetz Aaron T. , Starratt Valerie G.
Published: March 2008

Rape of women by men has occurred throughout recorded history and across cultures. In this article, we discuss rape from an evolutionary psychological perspective. Evolutionary psychology is a powerful heuristic tool that allows researchers to develop and test novel hypotheses about complex behaviors such as rape. Some researchers have argued that men have evolved psychological mechanisms that motivate them to rape in specific contexts. We discuss evidence consistent with this claim, and argue that a more nuanced view of men's rape behavior is necessary. We propose that it may be useful to characterize rapists as belonging to one of several types, distinguished by individual differences as well as by the circumstances in which they are predicted to commit rape. We discuss research evidence in support of each rapist type, as well as the need for future research. Finally, we discuss research concerning women's rape-avoidance psychology and behavior.
Thymol and related alkyl phenols activate the hTRPA1 channel
Authors: Lee S P , Buber M T , Yang Q , Cerne R , Cortés R Y , Sprous D G , Bryant R W
Published: March 2008

Background and purpose: Thymol, a major component of thyme and oregano, has medical uses in oral care products as an astringent and antibiotic. Its distinctive sharp odour and pungent flavour are considered aversive properties. The molecular basis of these aversive properties is not well understood.

Experimental approach: The ability of thymol to activate human transient receptor potential channel A1 (hTRPA1) expressed in stably transfected human embryonic kidney 293 (HEK293) cells was measured by membrane potential and calcium‐sensitive dyes in a fluorescence‐imaging plate reader (FLIPR) assay. Direct activation of hTRPA1 currents was measured by whole‐cell voltage clamp recording. Intracellular calcium changes were measured using fura‐2 dye. The FLIPR assay was also used to measure membrane potential changes elicited by thymol after pretreatment with camphor, a known TRPA1 inhibitor. The ability of related alkyl phenols to activate hTRPA1 was also determined.

Key results: Thymol potently activated a membrane potential response and intracellular calcium increase in hTRPA1‐expressing HEK293 cells in a concentration‐dependent manner. Activation by thymol desensitized hTRPA1 to further exposure to thymol or the known ligand allyl isothiocyanate (AITC). The related phenols 2‐tert‐butyl‐5‐methylphenol, 2,6‐diisopropylphenol (propofol) and carvacrol also activated hTRPA1. Phenols with less bulky carbon substitutions and lower logP values were less potent in general. The response to thymol was blocked by camphor.

Conclusions and implications: These results suggest a role for hTRPA1 activation in the reported pungent and aversive properties of some of these pharmaceutically important phenols.

British Journal of Pharmacology (2008) 153, 1739–1749; doi:10.1038/bjp.2008.85; published online 10 March 2008
C‐reactive protein and C1q regulate platelet adhesion and activation on adsorbed immunoglobulin G and albumin
Authors: Skoglund Caroline , Wetterö Jonas , Skogh Thomas , Sjöwall Christopher , Tengvall Pentti , Bengtsson Torbjorn
Published: March 2008

Blood platelets and C‐reactive protein (CRP) are both used clinically as markers of ongoing inflammation, and both participate actively in inflammatory responses, although the biological effects are still incompletely understood. Rapidly adhering platelets express receptors for complement factor 1q (C1q) and the Fc part of immunoglobulin G (IgG), and CRP is known to activate/regulate complement via C1q binding, and to ligate FcγRs. In the present study, we used normal human IgG pre‐adsorbed to a well‐characterized methylated surface as a model solid‐phase immune complex when investigating the effects of CRP and C1q on platelet adhesion and activation. Protein adsorption was characterized using ellipsometry and polyclonal antibodies, and human serum albumin (HSA) and non‐coated surfaces were used as reference surfaces. Platelet adhesion to IgG and HSA was inhibited by both C1q and CRP. Furthermore, CRP (moderately) and C1q (markedly) decreased the spreading of adhering platelets. The combination of C1q and CRP was slightly more potent in reducing cell adhesion to IgG, and also impaired the adhesion to HSA and non‐coated surfaces. Platelet production of thromboxane B2 (TXB2) was also reduced by C1q both in the presence and absence of CRP, whereas CRP alone had no effect on TXB2 production. We conclude that CRP and C1q regulate the behaviour of platelets, and that this may be an important immunoregulatory mechanism during inflammatory conditions.
Ungewöhnlicher Verlauf eines Guillain-Barré-Syndroms im Zusammenhang mit einer RS-Virusinfektion bei einem 10 Monate alten Säugling
Authors: Erler T. , Weidner B. , Wetzel U. , Grunske A.
Published: March 2008

Das Guillain-Barré-Syndrom (GBS; Synonyma: Polyneuritis, Polyradikulitis, Akute entzündliche demyelinisierende Polyradikuloneuropathie, Polyradikuloneuritis) ist eine akute, entzündliche, demyelinisierende Erkrankung des peripheren Nervensystems. Die Erkrankung präsentiert sich klinisch mit symmetrischen Lähmungen, Areflexie und ausgeprägten vegetativen Störungen. Respiratorisches Versagen und kardiovaskuläre Instabilität sind die Hauptgründe für die Übernahme eines Patienten mit GBS auf die Intensivstation. Der vorliegende Bericht schildert den ungewöhnlichen schweren Verlauf einer Polyradikuloneuritis bei einem 10 Monate alten Säugling und diskutiert RS-Viren als mögliche Auslöser. Bei einem ARDS im Kindesalter könnte eine Stickoxidbeatmung (NO) eine lebensrettende Option darstellen.
Successful Knowledge Transfer within Offshore Supplier Networks: A Case Study Exploring Social Capital in Strategic Alliances
Authors: Rottman Joseph W
Published: March 2008

Managing a global network of suppliers presents considerable challenges for large multinational corporations. Chief among these is how to effectively transfer knowledge among members of strategic alliances while maintaining tight control over intellectual property. This paper highlights the efforts of a Fortune 100 manufacturing firm (hereafter US Manufacturing) and its management of global IT suppliers. Using a social capital framework developed by Inkpen and Tsang (2005), we explore the supplier network at three levels (structural, cognitive, and relational) and present eight proven practices for creating, managing, and exploiting social capital within strategic alliances. The Inkpen and Tsang framework examines the linkages between knowledge transfer and social capital for three network types: intracorporate networks, strategic alliances, and industrial districts. We use the strategic alliance of US Manufacturing and its suppliers to illustrate salient social capital dimensions and the conditions and practices that facilitated knowledge transfer. These practices enabled US Manufacturing to improve knowledge transfer, decrease development costs, shorten cycle time, increase the quality of developed deliverables, quickly respond to changes in the regulatory environment, and, most importantly, build strong, strategic relationships with its suppliers.
Relation between exchange-only optimized potential and Kohn–Sham methods with finite basis sets, and effect of linearly dependent products of orbital basis functions
Authors: Görling Andreas , Heßelmann Andreas , Jones Martin , Levy Mel
Published: March 2008

Recently, Staroverov, Scuseria, and Davidson [J. Chem. Phys. 124, 141103 (2006)] presented examples of exchange-only optimized effective potential (xOEP) calculations that yield exactly the Hartree–Fock (HF) total energy. Here, building on their work, arguments showing under which conditions xOEP methods, with finite basis sets, do or do not yield the HF ground state energy but a higher one, are given. While the orbital products of a complete basis are linearly dependent, the HF ground state energy can only be obtained via a finite basis set xOEP scheme in the case that all products of occupied and unoccupied orbitals emerging from the employed orbital basis set are linearly independent of each other. Further, exchange potentials leading to the HF ground state energy likely exhibit unphysical oscillations and do not represent a Kohn–Sham (KS) exchange potential as a functional derivative of the exchange energy. These findings appear to explain the seemingly paradoxical results of Staroverov et al. that certain finite basis set xOEP calculations lead to the HF ground state energy despite the fact that within a real space (or complete basis) representation, the xOEP ground state energy is always higher than the HF energy. Moreover, independent of whether or not the occupied and unoccupied orbital products are linearly dependent, it is shown that finite basis set xOEP methods only represent exact exchange-only (EXX) KS methods, i.e., proper density-functional methods, if the orbital basis set and the auxiliary basis set representing the exchange potential are balanced to each other, i.e., if the orbital basis is comprehensive enough for a given auxiliary basis. Otherwise xOEP methods do not represent EXX KS methods and yield unphysical exchange potentials. The question whether a xOEP method properly represents a KS method with an exchange potential that is a functional derivative of the exchange energy is related to the problem of the definition of local multiplicative operators in finite basis representations. Plane wave calculations for bulk silicon illustrate the findings of this work.
Improvements in a-plane GaN crystal quality by a two-step growth process
Authors: Hollander J. L. , Kappers M. J. , McAleese C. , Humphreys C. J.
Published: March 2008

Nonpolar (112¯0) a-plane GaN films have been grown by metal-organic vapor deposition on r-plane (11¯02) sapphire. Lateral growth is favored using a low V:III ratio resulting in films with a smooth surface, while pitted films are grown at a high V:III ratio indicating preferential on-axis growth. High-resolution x-ray diffraction analysis of both film types showed a strong anisotropy in the peak width of the symmetric omega rocking curve with respect to the in-plane orientation, phi. In-plane isotropic behavior of crystallinity with overall reduced omega full width at half maximum values was achieved when the growth was initiated at a high V:III ratio before reducing the V:III ratio for film coalescence. An improvement of crystal quality through initial surface roughening was equally realized by the incorporation of partial-coverage SiNx interlayers.
Poly(D,L-lactide-co-glycolide) microcomposite containing magnetic iron core nanoparticles as a drug carrier
Authors: Naik Sweta , Carpenter Everett E.
Published: March 2008

Today many potent anticancer drugs like cisplatin are available which carry a number of side effects. A promising way of reducing the side effects is to target the drug to tissue sites by coating it with biocompatible materials like Poly (dl-lactide-co-glycolide) (PLGA) polymer where controlled drug release is achieved during the biodegradation of the polymer. Also the efficacy of anticancer drugs like cisplatin increases at elevated temperatures, so if local heating can be achieved where the drug is targeted. Local heating can be achieved by introducing iron core nanoparticles in the composites along with the drug, which can be heated by the 2.4 GHz microwaves. Local heating of the nanocomposites also helps to swell the polymer shell and enhance the drug release. The magnetic nanocomposites were synthesized using iron nanoparticles, PLGA and a fluorescent dye, tris-(2,2′bipyridyl) dichlororuthenium (II) using an oil-in-emulsion technique. The emulsion contains PLGA, dye, and iron nanoparticles dissolved in the oil phase and polyvinyl alcohol (PVA) as a stabilizer. As the sample is homogenized, and dried, uniform 100 nm composites are formed where the dye and iron nanoparticles are encapsulated in a PLGA shell. Control of the thickness and loading efficiency of the nanocomposite can be controlled by varying the ratio of PLGA, iron, and dye. The amount of loading was determined using TGA confirming from 20–50% (w/w) loading. As the dye is released from the composite the fluorescence intensity decreases due to self-quenching. This self-quenching allows for the determination of the release kinetics as a function of temperature using fluorescence spectroscopy. Initial results suggest that there is a release of 5–10% of the dye from the composite at 25°C and complete release after the nanocomposite reaches 90°C. Using local microwave heating the complete release of the dye can be accomplished with three two second pulses of 2.4 GHz microwaves. This allows for the complete drug delivery platform which allows for the controlled release using microwave frequency.
Understanding laser-induced ultrafast magnetization in ferromagnets: First-principles investigation
Authors: Zhang G. P. , Bai Yihua , Hübner W. , Lefkidis Georg , George Thomas F.
Published: March 2008

Ultrafast demagnetization in ferromagnets has attracted much attention both experimentally and theoretically for over a decade. This includes a lively debate as to whether the observed signal represents a true magnetization process. Here, a first-principles and time-dependent calculation is performed for ferromagnetic nickel under laser illumination to directly compute the magnetization and polarization changes. It is found that while the polarization exhibits both rapid and slow oscillations, the magnetization mainly shows a slow oscillation. The slow component of the polarization generally follows the magnetization evolution with a margin of 2–3fs deviation. The correlation between the magnetization and polarization tends to be better in the absence of laser radiation.
Efficient prediction of thermodynamic properties of quadrupolar fluids from simulation of a coarse-grained model: The case of carbon dioxide
Authors: Mognetti B. M. , Yelash L. , Virnau P. , Paul W. , Binder K. , Müller M. , MacDowell L. G.
Published: March 2008

Monte Carlo simulations are presented for a coarse-grained model of real quadrupolar fluids. Molecules are represented by particles interacting with Lennard–Jones forces plus the thermally averaged quadrupole-quadrupole interaction. The properties discussed include the vapor-liquid coexistence curve, the vapor pressure along coexistence, and the surface tension. The full isotherms are also accessible over a wide range of temperatures and densities. It is shown that the critical parameters (critical temperature, density, and pressure) depend almost linearly on a quadrupolar parameter q=Q*4∕T*, where Q* is the reduced quadrupole moment of the molecule and T* the reduced temperature. The model can be applied to a variety of small quadrupolar molecules. We focus on carbon dioxide as a test case, but consider nitrogen and benzene, too. Experimental critical temperature, density, and quadrupolar moment are sufficient to fix the parameters of the model. The resulting agreement with experiments is excellent and marks a significant improvement over approaches which neglect quadrupolar effects. The same coarse-grained model was also applied in the framework of perturbation theory in the mean spherical approximation. As expected, the latter deviates from the Monte Carlo results in the critical region, but is reasonably accurate at lower temperatures.
Dynamic modeling and experimental analysis of Terfenol-D rods for magnetostrictive actuators
Authors: Bottauscio O. , Chiampi M. , Lovisolo A. , Roccato P. E. , Zucca M.
Published: March 2008

In this paper magnetostrictive rods are analyzed coupling a magnetoelastic model of Terfenol-D rods based on Preisach theory with a finite element electromagnetic field solution, accounting for dynamic effects within the rod. The computed results, compared with experiments, evidence the influence of eddy currents and magnetization dynamic on the magnetostrictive rod behavior.
Design and analysis of thrust active magnetic bearing
Authors: Jang Seok-Myeong , Lee Un-Ho , Choi Jang-Young , Hong Jung-Pyo
Published: March 2008

This paper deals with the design and analysis of thrust active magnetic bearing (AMB). Using the analytical solutions for thrust, resistance, and inductance obtained from equivalent magnetic circuits method, we determine initial design parameters such as the size of magnetic circuit, coil diameter, and the number of turns by investigating the variation of thrust according to design parameters. Then, using nonlinear finite element analysis, a detailed design considering saturation is performed in order to meet required thrust under restricted conditions. Finally, by confirming that the design result is shown in good agreement with experimental results, the validity of design procedures for thrust AMB used in this paper is proved. In particular, the dynamic test results of the thrust AMB are also given to confirm the validity of the design.
Characteristics analysis of a high speed permanent magnet synchronous generator using the transfer relations theorem and equivalent circuit method
Authors: Jang Seok-Myeong , Ko Kyoung-Jin , Park Ji-Hoon , Cho Han-Wook , Hong Jung-Pyo
Published: March 2008

This paper presents analytical methods to predict the magnetic field distribution, electrical parameters, and output characteristics of a high speed synchronous generator equipped with surface-mounted permanent magnet. In order to analyze the magnetic field distribution and to estimate the electrical parameters, electromagnetic transfer relation (TR) theorem is employed. Moreover, output characteristics for variable resistive load and the operating speed are also obtained by solving the permanent magnet machine’s equivalent circuit equation. The analytical results are validated extensively by nonlinear finite element analysis and experimental results.
Identifying reversible and irreversible magnetization changes in prototype patterned media using first- and second-order reversal curves
Authors: Winklhofer Michael , Dumas Randy K. , Liu Kai
Published: March 2008

Arrays of nanomagnets have important potential applications as future generation ultrahigh-density patterned magnetic recording media, in which each nanomagnet constitutes a single bit. We introduce a powerful technique to identify and quantify reversible and irreversible magnetization changes, a key challenge in characterizing these systems. The experimental protocol consists of measuring a few families of second-order reversal curves along selected profiles in the first-order-reversal-curve diagram, which then can be decomposed into truly irreversible switching events and reversible magnetization changes. The viability of the method is demonstrated for arrays of sub-100-nm Fe nanomagnets, which exhibit complex magnetization reversal processes.
Chaotic signal detection and estimation based on attractor sets: Applications to secure communications
Authors: Rohde G. K. , Nichols J. M. , Bucholtz F.
Published: March 2008

We consider the problem of detection and estimation of chaotic signals in the presence of white Gaussian noise. Traditionally this has been a difficult problem since generalized likelihood ratio tests are difficult to implement due to the chaotic nature of the signals of interest. Based on Poincare’s recurrence theorem we derive an algorithm for approximating a chaotic time series with unknown initial conditions. The algorithm approximates signals using elements carefully chosen from a dictionary constructed based on the chaotic signal’s attractor. We derive a detection approach based on the signal estimation algorithm and show, with simulated data, that the new approach can outperform other methods for chaotic signal detection. Finally, we describe how the attractor based detection scheme can be used in a secure binary digital communications protocol.
Effects of Gd2O3 addition in YBa2Cu3O7−δ on the critical current density
Authors: Xu S. , Wu X. S. , Ma G. B. , Wang Z. H. , Gao J.
Published: March 2008

Y Ba 2 Cu 3 O 7 − δ (YBCO) powders with Gd2O3 additives are prepared by the solid state reaction method. X-ray diffraction with Rietveld refinements shows that both Gd2O3 and YBCO phases coexist in the products. With increasing additive content, the unit cell symmetry of YBCO phase remains unchanged but the grain size increases. The critical current density (Jc) exhibits a maximum at x=0.1 in YBCO+ xGd2O3 systems. Moreover, the addition of Gd2O3 in YBCO enhances Jc by applying the magnetic field, although the superconducting temperature (Tc) decreases slightly. We argue that the characteristic behavior of Jc may come from the counterbalance of two effects simultaneously, which was caused by the variation of superconductivity and the inhomogeneity of grain distribution in nanoscale.
Induced ordering in electrodeposited nanocrystalline Ni–Mn alloys
Authors: Stephen A. , Rossi F. , Nasi L. , Ferrari C. , Ponpandian N. , Ananth M. V. , Ravichandran V.
Published: March 2008

The Ni3Mn type of ordering in nanocrystalline NiMn films with different compositions prepared by electrodeposition was investigated by using x-ray diffraction, differential scanning calorimetry (DSC), thermogravimetric analyzer, Mössbauer spectroscopy, and transmission electron microscopy. The investigations reveal the existence of composition-induced Ni3Mn-type ordering in the as-deposited film of 76.2at.% Ni. The atomic disorder is characterized by an exothermic effect in DSC. An analysis of the broad exothermic transition reveals the stages of phase transformation leading to ordering. The Curie temperatures of the alloys were determined from thermomagnetic measurements, the maximum value obtained for the ordered sample. Mössbauer spectroscopy at room temperature reveals ordered (ferromagnetic) and disordered (paramagnetic) phases in the as-deposited films. Superlattice reflections observed in selected area electron diffraction pattern for the 76.2at.% Ni film alone further support the observation of composition-specific atomic ordering.
Separating interface state response from parasitic effects in conductance measurements on organic metal-insulator-semiconductor capacitors
Authors: Taylor D. M. , Alves N.
Published: March 2008

A simple model is developed for the admittance of a metal-insulator-semiconductor (MIS) capacitor which includes the effect of a guard ring surrounding the Ohmic contact to the semiconductor. The model predicts most of the features observed in a MIS capacitor fabricated using regioregular poly(3-hexylthiophene) as the active semiconductor and polysilsesquioxane as the gate insulator. In particular, it shows that when the capacitor is driven into accumulation, the parasitic transistor formed by the guard ring and Ohmic contact can give rise to an additional feature in the admittance-voltage plot that could be mistaken for interface states. When this artifact and underlying losses in the bulk semiconductor are accounted for, the remaining experimental feature, a peak in the loss-voltage plot when the capacitor is in depletion, is identified as an interface (or near interface) state of density of ∼4×1010cm−2eV−1. Application of the model shows that exposure of a vacuum-annealed device to laboratory air produces a rapid change in the doping density in the channel region of the parasitic transistor but only slow changes in the bulk semiconductor covered by the gold Ohmic contact.
The effects of a microbridge buffer layer on the sensitivity of a local ferromagnetic resonance probe
Authors: Benatmane Nadjib , Clinton T. W.
Published: March 2008

A new fabrication technique for a near-field microwave probe that greatly improves the sensitivity is presented. This design and fabrication has enabled quantitative measurements (with a probe as small as micron scale) that were not previously possible, such as ferromagnetic resonance in media with relatively small permeability, large damping, and high anisotropy (HK). The new method uses a focused ion beam to deposit and lithographically define a SiO2 or Pt buffer between the inner and outer conductors of a microcoax. A thin Cu film is then deposited, after which the Cu is etched in the field, preserving the Cu over the buffer to complete a microbridge. The buffer layer results in surface smoothness on the order of 10nm at the top and bottom (Cu∕buffer) surfaces of the Cu.
Structure-magnetic property correlations in the epitaxial FePt system
Authors: Trichy G. R. , Chakraborti D. , Narayan J. , Prater J. T.
Published: March 2008

We present findings on the effect of microstructure on magnetic properties of the epitaxial FePt system. Epitaxial c-axis oriented FePt was synthesized on Si (100) using TiN as a template buffer. The microstructure was progressively varied from a 9nm nanoparticle system to a 30nm thick continuous thin film. We found that individual nanoparticles showed higher coercivity than the continuous thin film. Within the nanoparticle regime, coercivity increased with increasing particle size. The highest coercivity of 13500Oe was realized for a beadlike microstructure, when the individual nanoparticles just begin to merge to form a continuous thin film.
Probing epitaxial growth of graphene on silicon carbide by metal decoration
Authors: Poon Siew Wai , Chen Wei , Tok Eng Soon , Wee Andrew T. S.
Published: March 2008

Using Co-decoration technique coupled with in situ scanning tunneling microscope (STM), the evolution of epitaxial graphene was found to preferentially begin at step edges of the silicon carbide surface and occurs with loss of Si and breakdown of C-rich (63×63)R30° template, which provides the C source for graphene growth. Interestingly, a new C-rich phase is also formed at the interface and it acts as a buffer layer for graphene from underlying bulk. STM reveals that graphene lies 2.3±0.3Å above the buffer layer, larger than sp3 C–C bond length (1.54Å) but shorter than graphite interlayer separation (3.37Å), suggesting a pseudo-van der Waals interfacial interaction.
Mixed ligands 8-hydroxyquinoline aluminum complex with high electron mobility for organic light-emitting diodes
Authors: Xu Bingshe , Chen Liuqing , Liu Xuguang , Zhou Hefeng , Xu Huixia , Fang Xiaohong , Wang Yanli
Published: March 2008

A mixed ligands 8-hydroxyquinoline complex (Alq2A) with improved electron mobility was designed for organic light-emitting diodes. The electron mobility in Alq2A was determined via transient electroluminescence (EL) from bilayer devices with structure of indium tin oxide/4,4′-bis[N-(1-naphthyl)-N-Phenyl amino]biphenyl/Alq2A∕LiF∕Al. It was found that the electron mobility in Alq2A is between (2.7and4.4)×10−6cm2∕Vs at electric fields ranging between 1.42×106 and 2.40×106V∕cm, which is higher than that in Alq3. The Alq2A also shows a higher EL efficiency in steady-state EL studies, which is considered to be derived from (1) improved electron mobility, (2) high fluorescene efficiency, and (3) good film-forming.
Excitonic and pair-related photoluminescence in ZnSe nanowires
Authors: Saxena Ankur , Yang Suxia , Philipose U. , Ruda Harry E.
Published: March 2008

It has been established that deviations from stoichiometry during the growth of ZnSe crystals result in point defects, which influence its electronic properties. We report on detailed photoluminescence results and their systematic analysis for ZnSe nanowires. We studied photoluminescence from vapor-phase grown undoped ZnSe nanowires grown under excess Zn conditions, and in particular the dependence on excitation intensity. Luminescence spectra were characterized by strong near-band-edge luminescence with negligible deep-level emission. We observed excitonic emission at 2.794 eV related to the neutral donor at VSe. The binding energy of the exciton was found to be 7 meV, and that of the donor was 35 meV. Two donor-acceptor pair transitions at 2.714 and 2.686 eV were also observed, which can be related to the defect complexes of native defects with other native defects or with common unintentional shallow donors and acceptors. The ionization energies of both donors were 27 meV, whereas those of the acceptors were 102 and 139 meV, respectively.
Ga
In
P
∕
Ga
As
dual junction solar cells on Ge∕Si epitaxial templates
Authors: Archer Melissa J. , Law Daniel C. , Mesropian Shoghig , Haddad Moran , Fetzer Christopher M. , Ackerman Arthur C. , Ladous Corinne , King Richard R. , Atwater Harry A.
Published: March 2008

Large area, crack-free GaInP∕GaAs double junction solar cells were grown by metal organic chemical vapor deposition on Ge∕Si templates fabricated using wafer bonding and ion implantation induced layer transfer. Photovoltaic performance of these devices was comparable to those grown on bulk epi-ready Ge, demonstrating the feasibility of alternative substrates fabricated via wafer bonding and layer transfer for growth of active devices on lattice mismatched substrates.