bluuebunny/crossref_metadata_2025 huggingface dataset:
Barth and Loyola on Communication of the Word of God
Authors: Starkloff Carl F.
Published: February 2009

Ten years ago it might have seemed odd to place side by side two men like Karl Barth (1886-1968) and Ignatius Loyola (1491-1556), the former considered a ‘modern church father’ of the Reformation and the latter an implacable foe of that tradition in its fledgling state. What is significant however is that their essential spiritual thrust took such similar directions. It is the similarity in essentials that first drew this writer to begin comparing the thought of the two men, but more than a similarity is involved here. An examination of the attitudes of the two towards Christian proclamation and communication provides striking ecumenical possibilities, and allows Roman Catholics and Protestants to see how close their traditions are in so many cases, if only a careful effort is made to understand the other's language. Loyola himself, at the outset of his spiritual manual, offers us a pattern for sensitivity in theological discussion:

To assure better cooperation between the one who is giving the Exercises and the exercitant, and more beneficial results for both, it is necessary to suppose that every good Christian is more ready to put a good interpretation on another's statement than to condemn it as false. If an orthodox construction cannot be put on a proposition, the one who made it should be asked how he understands it. If he is in error, he should be corrected with all kindness. If this does not suffice, all appropriate means should be used to bring him to a correct interpretation, and so defend the proposition from error.
Lonergan's Method: Its Nature and Uses
Authors: Meynell Hugo A.
Published: February 2009

Of the various attempts to turn theology into a systematic science, that of Bernard Lonergan seems to me by far the most impressive. But it is not yet as well known as it deserves. In what follows I shall try to describe Lonergan's method, and to indicate why I think that it is of importance.
The Dark Ages and Twentieth Century Africa: A Comparison in Churchmanship
Authors: Stone W. V.
Published: February 2009

Bishop Stephen Neill, in his Survey of the Training of the Ministry in Africa, writes as follows: ‘I could not but feel profound sympathy with the African student who remarked: “It seems to me that missionaries are much too hard in their judgments on the African Churches. Did you never have a period of struggle in your own Churches? ” Indeed we did. In that moment I suddenly saw that, for the African Churches in their contemporary struggle, the most important period is the one that ordinarily we never teach them in detail, the Dark Ages.… They wrestle with precisely the same difficulties and are called to find anew the way out of the twilight of the coexistence of the old and new into a more genuinely Christian life and social order. ’
Satan, Demons, and the Kingdom of God
Authors: Hiers Richard H.
Published: February 2009

As reported in the synoptic gospels, one of the most characteristic features of Jesus' activity was his campaign against the household of Satan, the demons. And yet Jesus' work as demon-exorcist has generally received little attention. Perhaps this is because for some time now the idea of demon-possession has been alien to the viewpoints of both liberal and conservative interpreters of his ministry. We do not believe in Satan and demons; surely Jesus could not have done so either!
Noble gas and stable isotope geochemistry of thermal fluids from Deception Island, Antarctica
Authors: Kusakabe Minoru , Nagao Keisuke , Ohba Takeshi , Seo Jung Hun , Park Sung-Hyun , Lee Jong Ik , Park Byong-Kwon
Published: February 2009

New stable isotope and noble gas data obtained from fumarolic and bubbling gases and hot spring waters sampled from Deception Island, Antarctica, were analysed to constrain the geochemical features of the island's active hydrothermal system and magmatism in the Bransfield back-arc basin. The 3He/4He ratios of the gases (< 9.8 × 10-6), which are slightly lower than typical MORB values, suggest that the Deception Island magma was generated in the mantle wedge of a MORB-type source but the signature was influenced by the addition of radiogenic 4He derived from subducted components in the former Phoenix Plate. The N2/He ratios of fumarolic gas are higher than those of typical mantle-derived gases suggesting that N2 was added during decomposition of sediments in the subducting slab. The δ13C values of -5 to -6‰ for CO2 also indicate degassing from a MORB-type mantle source. The H2/Ar- and SiO2 geothermometers indicate that the temperatures in the hydrothermal system below Deception Island range from ~150°C to ~300°C. The δD and δ18O values measured from fumarolic gas and hot spring waters do not indicate any contribution of magmatic water to the samples. The major ionic components and δD-δ18O-δ34S values indicate that hot spring waters are a mixture of local meteoric water and seawater. Mn and SiO2 in spring waters were enriched relative to seawater reflecting water-rock interaction at depth.
Breakthrough of attenuating contaminant plumes in pumping wells: Analytical model and implications for integral pumping tests
Authors: Bayer‐Raich Martí , Jarsjö Jerker , Teutsch Georg
Published: February 2009

Monitoring of contaminant plumes and predicting their future fate are essential for effective management of groundwater contaminants. Solute breakthrough curves from operating pumping wells can provide information on the water quality in relatively large aquifer regions, which may be unavailable to instrumentation and direct measurement for practical and/or economical reasons. Relations between spatially varying aquifer concentrations C0(x, y) initially surrounding a well and temporally varying concentrations of subsequently extracted well water, Cp(t), then need to be quantified. However, limited applicability of analytical expressions and numerical inaccuracies related to solving transport equations for converging flow fields hamper such quantifications even in homogeneous aquifers. We use a stream‐tube approach and provide a general problem formulation that accounts for first‐order degradation and linear, instantaneous, sorption/retardation in heterogeneous aquifers. An analytical expression is obtained for homogeneous aquifer conditions (in the well vicinity), relating any given initial C0(x, y) function and the subsequent contaminant breakthrough Cp(t) in the well. Results for wide plumes subject to first‐order degradation show that concentrations at the extraction well will increase as a function of pumping time. This increase is despite the fact that late‐time data reflect longer transport paths (to the well), along which mass is removed through degradation. We also derive unique solutions for the inverse problem, in particular considering how the average contaminant concentration Cav (averaged along a control plane through the well within its capture zone, perpendicular to the mean groundwater flow direction) depends on the measurable Cp(t). The solutions demonstrate that the longer the pumping time, the more sensitive the solutions for Cav become to degradation rate constants, which if needed can be determined in situ using multiple control planes.
Warm ocean anomaly, air sea fluxes, and the rapid intensification of tropical cyclone Nargis (2008)
Authors: Lin I.‐I. , Chen Chi‐Hong , Pun Iam‐Fei , Liu W. Timothy , Wu Chun‐Chieh
Published: February 2009

On 2 May 2008, category‐4 tropical cyclone Nargis devastated Myanmar. It was observed that just prior to its landfall, Nargis rapidly intensified from a weak category‐1 storm to an intense category‐4 storm within only 24 h. Using in situ ocean depth‐temperature measurements and satellite altimetry, it is found that Nargis' rapid intensification took place on a pre‐existing warm ocean anomaly in the Bay of Bengal. In the anomaly, the subsurface ocean is evidently warmer than climatology, as characterized by the depth of the 26°C isotherm of 73–101 m and the tropical cyclone heat potential of 77–105 kj cm−2. This pre‐existing deep, warm subsurface layer leads to reduction in the cyclone‐induced ocean cooling, as shown from the ocean mixed layer numerical experiments. As a result, there was a near 300% increase in the air‐sea enthalpy flux to support Nargis' rapid intensification.
Glacier decline between 1963 and 2006 in the Cordillera Real, Bolivia
Authors: Soruco Alvaro , Vincent Christian , Francou Bernard , Gonzalez Javier Francisco
Published: February 2009

The volume changes of 21 glaciers in the Cordillera Real have been determined between 1963 and 2006 using photogrammetric measurements. These data form the longest series of mass balances obtained with such accuracy in the tropical Andes. Our analysis reveals that temporal mass balance fluctuations are similar, revealing a common response to climate over the entire studied region. The mass of these glaciers has clearly been decreasing since 1975 without any significant acceleration of this trend over recent years. We have found a clear relationship between the average mass balance of these glaciers as a function of exposure and altitude. From this relationship, the ice volume loss of 376 glaciers has been assessed in this region. The results show that these glaciers lost 43% of their volume between 1963 and 2006, essentially over the 1975–2006 period and 48% of their surface area between 1975 and 2006.
Regularized extremal bounds analysis (REBA): An approach to quantifying uncertainty in nonlinear geophysical inverse problems
Authors: Meju Max A.
Published: February 2009

Geophysical measurements are band‐limited in nature, contain noise, and bear a nonlinear relationship to the subterranean features being sampled. These result in uncertainty in data interpretation and necessitate a regularization approach. Although model uncertainty and non‐uniqueness can be reduced by combining measurements of fundamentally different physical attributes of a subsurface target under investigation or by using available a priori information about the target, quantifying non‐uniqueness remains a difficult task in nonlinear geophysical inversion. This paper develops a new theoretical framework for regularized extremal bounds analysis (REBA) of model uncertainty using the most‐squares formalism. The nonlinear most‐squares method allows for combining data constraints and their associated uncertainties in an objective manner to determine the model bounds. By making the assumption that the relevant bounding models must sample the same underlying geology, it is proposed that structural dissimilarity between the extreme models can be quantified using the cross‐products of the gradients of their property fields and should serve as an objective measure of interpretational uncertainty in multidimensional inversion.
Global pattern of Titan's dunes: Radar survey from the Cassini prime mission
Authors: Lorenz Ralph D. , Radebaugh Jani
Published: February 2009

We present a map of the orientation and extent of Titan's sand dunes derived from the complete radar imaging dataset from the Cassini prime mission. The 16,000 dune segments we have mapped cover ∼8% of the Titan's surface (suggesting a total coverage of ∼20%), are confined within 30° of the equator, and show local and regional deviations of dune orientation of up to about 40° from due Eastwards. There is no obvious global longitudinal pattern, although some divergence with latitude is apparent. The most striking pattern is one of collimation by and divergence around bright and/or high terrain. Obstacles 100–300 m high obstruct dunes when the local slope is 1/50 or steeper, while slopes 1/200 or shallower cause dunes to thin out as they climb, or to deviate around the obstacles.
Influence of anthropogenic sulfate and black carbon on upper tropospheric clouds in the NCAR CAM3 model coupled to the IMPACT global aerosol model
Authors: Liu Xiaohong , Penner Joyce E. , Wang Minghuai
Published: February 2009

The influence of anthropogenic aerosol (sulfate and soot) on upper tropospheric (UT) clouds through ice nucleation is studied using the NCAR Community Atmospheric Model Version 3 (CAM3) with a double moment ice microphysics treatment coupled to a global aerosol model (LLNL/UMich IMPACT). Present‐day and preindustrial simulations are performed and compared for two scenarios. In the first scenario, the homogeneous freezing of sulfate particles dominates cirrus cloud formation in the upper troposphere (HOM). In the second scenario, both homogeneous and heterogeneous ice nucleation and their competition (HET) are allowed. In the HOM scenario, anthropogenic sulfate results in a global annual mean change of long‐wave cloud forcing (LWCF) of 0.20 ± 0.09 W m−2 and short‐wave cloud forcing (SWCF) of 0.30 ± 0.17 W m−2 and an increase of upper tropospheric/lower stratospheric (UT/LS) water vapor by ∼10%. In the HET scenario, anthropogenic soot may increase global cirrus cloud cover by ∼2% and UT/LS water vapor by 40% with a change in LWCF of 1.5 W m−2 (with 1.35 ± 0.15 W m−2 from surface soot and 0.12 ± 0.17 W m−2 from aircraft soot) if soot acts as efficient ice nuclei (IN) with a threshold ice nucleation RHi of 120–130%. Aerosol effects are most evident (larger than natural variability) over polar regions. However, their influence is significantly reduced if soot has a threshold RHi of 140% with an LWCF change of only 0.23 W m−2 (with 0.17 ± 0.18 W m−2 from surface soot and 0.06 ± 0.16 W m−2 from aircraft soot), and cloud forcing changes are statistically insignificant (less than the natural variability). Our results reinforce the importance of understanding ice nucleation on soot from the perspective of their global climate impact.
Archive Compiles New Resource for Global Tropical Cyclone Research
Authors: Knapp Kenneth R. , Kruk Michael C. , Levinson David H. , Gibney Ethan J.
Published: February 2009

The International Best Track Archive for Climate Stewardship (IBTrACS) compiles tropical cyclone best track data from 11 tropical cyclone forecast centers around the globe, producing a unified global best track data set (M. C. Kruk et al., A technique for merging global tropical cyclone best track data, submitted to Journal of Atmospheric and Oceanic Technology, 2008). Best track data (so called because the data generally refer to the best estimate of a storm's characteristics) include the position, maximum sustained winds, and minimum central pressure of a tropical cyclone at 6‐hour intervals.

Despite the significant impact of tropical cyclones on society and natural systems, there had been no central repository maintained for global best track data prior to the development of IBTrACS in 2008. The data set, which builds upon the efforts of the international tropical forecasting community, has become the most comprehensive global best track data set publicly available. IBTrACS was created by the U.S. National Oceanic and Atmospheric Administration's National Climatic Data Center (NOAA NCDC) under the auspices of the World Data Center for Meteorology.
Investigating Age Resolution in Laser Ablation Geochronology: Workshop on Data Handling in LA‐ICP‐MSU‐Th‐Pb Geochronology; Vancouver, British Columbia, Canada, 12–13 July 2008
Authors: Horstwood Matt , Kosler Jan , Jackson Simon , Pearson Norman , Sylvester Paul
Published: February 2009

Laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) uranium‐thorium‐lead (U‐Th‐Pb) dating is an increasingly popular approach for determining the age of mineral grains and the timing of geological events. The spatial resolution offered by this technique allows detailed investigations of complex igneous and metamorphic processes, and the speed of data capture allows vast amounts of information to be gathered rapidly. Laser ablation U‐Th‐Pb dating is therefore becoming an increasingly influential technique to the geochronology community, providing cost‐effective and ready access to age data for laboratories and end users worldwide.

However, complications in acquiring, processing, and interpreting data can lead to inaccurate age information entering the literature. With the numbers of practitioners expanding rapidly, the need to standardize approaches and resolve difficulties (particularly involving the subjectivity in processing laser ablation U‐Th‐Pb data) is becoming important.
The Role of Stem Cell Factor and Granulocyte-Colony Stimulating Factor in Brain Repair during Chronic Stroke
Authors: Piao Chun-Shu , Gonzalez-Toledo Maria E , Xue Yue-Qiang , Duan Wei-Ming , Terao Satoshi , Granger D Neil , Kelley Roger E , Zhao Li-Ru
Published: February 2009

Chronic stroke is a highly important but under-investigated scientific problem in neurologic research. We have reported earlier that stem cell factor (SCF) in combination with granulocyte-colony stimulating factor (G-CSF) treatment during chronic stroke improves functional outcomes. Here we have determined the contribution of bone marrow-derived cells in angiogenesis and neurogenesis, which are enhanced by SCF + G-CSF treatment during chronic stroke. Using bone marrow tracking, flow cytometry, 2-photon live brain imaging, and immunohistochemistry, we observed that the levels of circulating bone marrow stem cells (BMSCs) (CD34+ /c-kit +) were significantly increased by SCF +G-CSF treatment. In addition, live brain imaging revealed that numerous bone marrow-derived cells migrate into the brain parenchyma in the treated mice. We also found that bone marrow-derived cells, bone marrow-derived endothelial cells, vascular density, and bone marrow-derived neurons were significantly augmented by SCF + G-CSF. It is interesting that, in addition to the increase in bone marrow-derived endothelial cells, the number of bone marrow-derived pericytes was reduced after SCF + G-CSF treatment during chronic stroke. These data suggest that SCF + G-CSF treatment can enhance repair of brain damage during chronic stroke by mobilizing BMSCs, and promoting the contribution of bone marrow-derived cells to angiogenesis and neurogenesis.
Neuroprotective Effects of Mesenchymal Stem Cells Derived from Human Embryonic Stem Cells in Transient Focal Cerebral Ischemia in Rats
Authors: Liu Yi-Ping , Seçkin Hakan , İzci Yusuf , Du Zhong Wei , Yan Yi-Ping , Başkaya Mustafa K
Published: February 2009

Embryonic mesenchymal stem cells (eMSCs) were first derived from human embryonic stem cells (hESCs) overexpressing green fluorescence protein (GFP). They expressed CD29, CD44, CD73, CD105, CD166 and nestin, but not CD34, CD45, CD106 SSEA-4 or Oct3/4. Twenty million eMSCs in 1mL of phosphate-buffered saline (PBS) were injected into the femoral veins of spontaneously hypertensive rats after transient middle cerebral artery occlusion. The migration and differentiation of the eMSCs in the ischemic brain were analyzed. The results revealed that eMSCs migrated to the infarction region and differentiated into neurons, which were positive for β-tubulin III, microtubule-associated protein 2 (MAP2), HuC, neurofilament and human nuclear antibody, and to vascular endothelial cells, which were positive for von Willebrand factor (vWF). The transplanted cells survived in the infarction region for at least 4 weeks. Adhesive removal function significantly improved in the first week after cell transplantation, and rotarod motor function significantly improved starting from the second week. The infarction volume in the eMSC group was significantly smaller than that in the PBS control group at 4 weeks after infusion. The results of this study show that when administered intravenously, eMSCs differentiated into neuronal and endothelial cells, reduced the infarction volume, and improved behavioral functional outcome significantly in transient focal cerebral ischemia.
AMPK and the biochemistry of exercise: implications for human health and disease
Authors: Richter Erik A. , Ruderman Neil B.
Published: February 2009

AMPK (AMP-activated protein kinase) is a phylogenetically conserved fuel-sensing enzyme that is present in all mammalian cells. During exercise, it is activated in skeletal muscle in humans, and at least in rodents, also in adipose tissue, liver and perhaps other organs by events that increase the AMP/ATP ratio. When activated, AMPK stimulates energy-generating processes such as glucose uptake and fatty acid oxidation and decreases energy-consuming processes such as protein and lipid synthesis. Exercise is perhaps the most powerful physiological activator of AMPK and a unique model for studying its many physiological roles. In addition, it improves the metabolic status of rodents with a metabolic syndrome phenotype, as does treatment with AMPK-activating agents; it is therefore tempting to attribute the therapeutic benefits of regular physical activity to activation of AMPK. Here we review the acute and chronic effects of exercise on AMPK activity in skeletal muscle and other tissues. We also discuss the potential role of AMPK activation in mediating the prevention and treatment by exercise of specific disorders associated with the metabolic syndrome, including Type 2 diabetes and Alzheimer's disease.
Phosphatidylinositol metabolism and membrane fusion
Authors: Poccia Dominic , Larijani Banafshé
Published: February 2009

Membrane fusion underlies many cellular events, including secretion, exocytosis, endocytosis, organelle reconstitution, transport from endoplasmic reticulum to Golgi and nuclear envelope formation. A large number of investigations into membrane fusion indicate various roles for individual members of the phosphoinositide class of membrane lipids. We first review the phosphoinositides as membrane recognition sites and their regulatory functions in membrane fusion. We then consider how modulation of phosphoinositides and their products may affect the structure and dynamics of natural membranes facilitating fusion. These diverse roles underscore the importance of these phospholipids in the fusion of biological membranes.
A Pyk2–Vav1 complex is recruited to β3-adhesion sites to initiate Rho activation
Authors: Gao Chunlei , Blystone Scott D.
Published: February 2009

Integrin αvβ3-mediated adhesion of haemopoietic cells to vitronectin results in β3 tyrosine phosphorylation and Rho activation which is necessary for adhesion. Previously, we have shown that the RhoGEF (Rho guanine-nucleotide-exchange factor) Vav1 could associate indirectly with αvβ3 during leucocyte adhesion to vitronectin. In the present study, we have identified the non-receptor tyrosine kinase Pyk2 (proline-rich tyrosine kinase 2) as the adaptor protein that links Vav1 with αvβ3. The association of Pyk2 and Vav1 with β3 relies on the presence of Tyr747 in β3, the primary site of β3 phosphorylation. However, association of Pyk2 with Vav1 is independent of β3 tyrosine phosphorylation. Formation of a Pyk2–Vav1 complex occurs upon cell adhesion and Pro717 of Pyk2 plays a key role in Pyk2 interaction with Vav1. Utilizing purified recombinant proteins, we confirmed the direct interaction between Pyk2 and Vav1 In vitro. Cells transfected with GFP (green fluorescent protein)–Pyk2-P717A demonstrated severely suppressed cytoskeletal reorganization, impaired Vav1 recruitment, decreased Rho GTPase activation and loss of cell adhesion. Using siRNA (small interfering RNA) to specifically reduce Pyk2 levels in cells resulted in disrupted association between Vav1 and β3 and impaired cell adhesion. These results indicate that Pyk2 is a critical signalling molecule downstream of β3 integrin tyrosine phosphorylation and mediates Vav1 recruitment to accomplish actin reorganization necessary for adhesion.
Twenty years of experimental and direct numerical simulation access to the velocity gradient tensor: What have we learned about turbulence?
Authors: Wallace James M.
Published: February 2009

Twenty years ago there was no experimental access to the velocity gradient tensor for turbulent flows. Without such access, knowledge of fundamental and defining properties of turbulence, such as vorticity dissipation, and strain rates and helicity, could not be studied in the laboratory. Although a few direct simulations at very low Reynolds numbers had been performed, most of these did not focus on properties of the small scales of turbulence defined by the velocity gradient tensor. In 1987 the results of the development and first successful use of a multisensor hot-wire probe for simultaneous measurements of all the components of the velocity gradient tensor in a turbulent boundary layer were published by Balint et al. [Advances in Turbulence: Proceedings of the First European Turbulence Conference (Springer-Verlag, New York, 1987), p. 456]. That same year measurements of all but one of the terms in the velocity gradient tensor were carried out, although not simultaneously, in the self-preserving region of a turbulent circular cylinder wake by Browne et al. [J. Fluid Mech. 179, 307 (1987)], and the first direct numerical simulation (DNS) of a turbulent channel flow was successfully carried out and reported by Kim et al. [J. Fluid Mech. 177, 133 (1987)], including statistics of the vorticity field. Also in that year a DNS of homogeneous shear flow by Rogers and Moin [J. Fluid Mech. 176, 33 (1987)] was published in which the authors examined the structure of the vorticity field. Additionally, Ashurst et al. [Phys. Fluids 30, 2343 (1987)] examined the alignment of the vorticity and strainrate fields using this homogeneous shear flow data as well as the DNS of isotropic turbulence of Kerr [J. Fluid Mech. 153, 31 (1985)] who had initiated such studies. Furthermore, Metcalfe et al. [J. Fluid Mech. 184, 207 (1987)] published results from their direct simulation of a temporally developing planar mixing layer in which they examined coherent vortical states resulting from secondary instabilities. Since then several experimentalists have used multisensor hot-wire probes of increasing complexity in turbulent boundary layers, wakes, jets, mixing layers, and grid flows. Numerous computationalists have employed DNS in a wide variety of turbulent flows at ever increasing Reynolds numbers. Particle image velocimetry and other optical methods have been rapidly developed and advanced during these two decades which have provided other means of access to these fundamental properties of turbulence. This paper reviews highlights of these remarkable developments and points out some of the most important things we have learned about turbulence as a result.
Theoretical investigation of the water/corundum (0001) interface
Authors: Polly Robert , Schimmelpfennig Bernd , Flörsheimer Mathias , Kruse Klaus , AbdElMonem Ahmed , Klenze Reinhardt , Rauhut Guntram , Fanghänel Thomas
Published: February 2009

For the reliable long-term modeling of the actinide migration in geological formations, the adsorption/desorption properties and the reactivity of mineral surfaces must be understood at the molecular level. The adsorption of radioisotopes at mineral surfaces of the aquifer is an important process that leads to the retention of contaminants such as radionuclides. Their transport by the ground water is either retarded or even completely inhibited by the presence of such a surface. Accordingly, this subject is of main importance for the safety assessment of nuclear waste repositories. As part of a joint theoretical/experimental effort, the interaction of water with the corundum (0001) surface is studied using several theoretical methods (Møller–Plesset perturbation theory, coupled cluster singles doubles with triplet corrections, as well as density functional theory). We focus in this study on the determination of the bond lengths and tilt angles of the surface OH species and their respective vibrational frequencies. The theoretical results are confirmed by subsequent simulation of the interface selective nonlinear sum frequency spectra. The excellent agreement of the simulated with the experimental spectra allows an assignment of the observed peaks in the sum frequency spectra of the water/corundum (0001) interface on the basis of our theoretical data. In this theoretical study we are able to give a unique interpretation of the observed sum frequency spectra of the water/corundum (0001) interface.
New Fe-metalloids based nanocrystalline alloys with high Bs of 1.9T and excellent magnetic softness
Authors: Makino Akihiro , Men He , Kubota Takeshi , Yubuta Kunio , Inoue Akihisa
Published: February 2009

The melt-spun Fe83.3–84.3Si4B8P3–4Cu0.7 alloys have a heterogeneous amorphous structure including a large amount of α-Fe-like clusters. Compared with the FeSiB alloys, the particle size rapidly decreases from several hundred nanometers to 2–3nm due to the proper amounts of simultaneous P and Cu additions. By controlling the crystallization process, a homogeneous nanocrystalline structure composed by small α-Fe grains with size of 10–17nm in diameter can be realized from the heterogeneous amorphous alloys. The nanocrystallized Fe83.3–84.3Si4B8P3–4Cu0.7 alloys show the extremely high saturation magnetic flux density of 1.88–1.94T sufficiently near to 1.97T of Fe-3.5mass%Si crystalline soft magnetic alloys, and exhibit low coercivity of less than 10A∕m and higher effective permeability of 16 000–25 000 at 1kHz due to the simultaneous realization of the homogeneous nanocrystalline structure and the small magnetostriction of (2–3)×10−6. In addition, the nanocrystalline alloys exhibit the superior core loss to the representative Fe78Si9B13 amorphous alloy at 50Hz.
Spin-dependent tunneling conductance in two-dimensional structures at zero magnetic field
Authors: Rozhansky I. V. , Averkiev N. S.
Published: February 2009

The influence of the spin-orbit interaction on the tunneling between two-dimensional electron layers is considered. A general expression for the tunneling current is obtained with the Rashba and Dresselhaus effects and also elastic scattering of charge carriers on impurities taken into account. It is shown that the particular form of the tunneling conductance as a function of the voltage between layers is extremely sensitive to the relationship between the Rashba and Dresselhaus parameters. This makes it possible to determine the parameters of the spin-orbit interaction and the quantum scattering time directly from measurements of the tunneling conductance in the absence of magnetic field.
Magnetotransport in two-dimensional n-InGaAs∕GaAs double-quantum-well structures near the transition from the insulator to the quantum Hall effect regime
Authors: Arapov Yu. G. , Karskanov I. V. , Harus G. I. , Neverov V. N. , Shelushinina N. G. , Yakunin M. V.
Published: February 2009

The temperature and magnetic-field dependence of the components of the conductivity and resistivity tensors are calculated with the quantum corrections due to the weak localization effect and electron-electron interaction taken into account in the diffusion and ballistic regimes. The corrections to the conductivity from the weak localization and electron-electron interaction and also the influence of spin and oscillation effects are taken into account by a renormalization of the transport relaxation time of the electron momentum, with the result that the Drude conductivity becomes temperature dependent. A calculation of the components of the conductivity and resistivity tensors is carried out with the use of the theoretical values of the parameters of the theory of quantum corrections, which are determined solely by the values of the carrier density and mobility of a particular sample. The results of the calculation are compared with experimental results for two-dimensional n-InGaAs∕GaAs structures with double quantum wells. It is shown that taking only the quantum corrections into account with the theoretical values of the parameters does not permit even a qualitative description of experiment, and it is therefore necessary to take additional temperature-dependent contributions to the Drude conductivity into account.
Peculiarities of the ferromagnetic ordering in diluted magnetic insulators
Authors: Kikoin K.
Published: February 2009

The present state of experimental and theoretical research on diluted magnetic insulators (thin oxide films doped with transition metals) is discussed. The fundamentally irremovable thermodynamic nonequilibrium character of these films makes it possible for long-range ferromagnetic order to be established in them or for a highly nonuniform multiphase state (superparamagnet) to form. In all cases a fundamental role is played by concomitant defects (oxygen vacancies, shallow donors and acceptors).
Ultrasonic investigations of the Jahn–Teller effect in a ZnSe:Fe2+ crystal
Authors: Gudkov V. V. , Lonchakov A. T. , Zhevstovskikh I. V. , Sokolov V. I. , Surikov V. T.
Published: February 2009

The temperature dependence of the absorption and velocity of transverse ultrasonic waves propagating in the [110] direction in a ZnSe:Fe2+ crystal with the iron impurity of n=2.2×1019cm−3 is investigated in the temperature interval 1.4–100K at a frequency of 53MHz. For the slow transverse mode an absorption peak at 7.3K and a decrease of the phase velocity below 40K are found, while no such features are observed for the fast mode. The anomalies are interpreted as manifestations of the Jahn–Teller effect. The softening of the elastic modulus (C11–C12)∕2 indicates that the local distortions in ZnSe:Fe2+ are tetragonal. Under the assumption that the absorption maximum is of a relaxational nature, the temperature dependence of the relaxation time is recovered from the data, and the values of the potential barrier height and vibronic frequency are obtained.
Field dependence of collective spin modes in transversely magnetized stripes with homogeneous and alternating width
Authors: Tacchi S. , Madami M. , Gubbiotti G. , Carlotti G. , Goolaup S. , Adeyeye A. O. , Nguyen H. T. , Cottam M. G.
Published: February 2009

Brillouin light scattering is used to study the spin-wave properties of arrays of closely spaced magnetic stripes with both homogeneous and alternating width, thickness of 30 nm, and edge-to-edge spacing of 55 nm. Experiments are performed with both the transferred wave vector and the applied magnetic field in the direction transverse to the length of the stripes, i.e., in the hard magnetization direction. When the transverse applied field is decreased from a relatively large value (0.15 T) down to zero, the overall direction of the stripe magnetization gradually switches from the transverse to the preferred longitudinal orientation, as confirmed by the shape of the Kerr hysteresis loops. The measured frequencies were compared to numerical calculations obtained for Permalloy stripe arrays by a microscopic dipole-exchange theory. A good overall agreement is achieved between experiment and theory, thanks to the inclusion of the dynamical interstripe dipolar coupling.
The subtle business of model reduction for stochastic chemical kinetics
Authors: Gillespie Dan T. , Cao Yang , Sanft Kevin R. , Petzold Linda R.
Published: February 2009

This paper addresses the problem of simplifying chemical reaction networks by adroitly reducing the number of reaction channels and chemical species. The analysis adopts a discrete-stochastic point of view and focuses on the model reaction set S1⇌S2→S3, whose simplicity allows all the mathematics to be done exactly. The advantages and disadvantages of replacing this reaction set with a single S3-producing reaction are analyzed quantitatively using novel criteria for measuring simulation accuracy and simulation efficiency. It is shown that in all cases in which such a model reduction can be accomplished accurately and with a significant gain in simulation efficiency, a procedure called the slow-scale stochastic simulation algorithm provides a robust and theoretically transparent way of implementing the reduction.
Femtosecond laser-induced periodic surface structures revisited: A comparative study on ZnO
Authors: Dufft D. , Rosenfeld A. , Das S. K. , Grunwald R. , Bonse J.
Published: February 2009

Laser-induced periodic surface structures (LIPSS) (ripples) with different spatial characteristics have been observed after irradiation of single-crystalline zinc oxide surfaces with multiple linearly polarized femtosecond pulses (150–200 fs, 800 nm) in air. For normal incident laser radiation, low spatial frequency LIPSS (LSFL) with a period (630–730 nm) close to the wavelength and an orientation perpendicular to the laser polarization have been found in the fluence range between ∼0.7 and ∼0.8 J/cm2 and predominantly for pulse numbers up to N=100. For lower fluences (0.5–0.7 J/cm2), a sharp transition from the LSFL features toward the formation of high spatial frequency LIPSS (HSFL) appears at any given pulse number below N=100. The HSFL are always parallel to the LSFL, exhibit spatial periods between 200 and 280 nm, and completely substitute the LSFL for pulse numbers N>100. Additionally, the influence of the angle of incidence has been studied experimentally for both LIPSS types revealing a different behavior. Experimental evidence for surface scattered second harmonic generation is presented in the regime of HSFL formation. Moreover, we will show that the HSFL structures on ZnO surfaces can be fully explained by an extension of the existing LIPSS theories if the photoexcitation of the dielectric material (affecting its transient optical properties) is considered in the frame of a simple Drude model along with the second harmonic generation at the irradiated surface. Based on our analysis, the current models of femtosecond laser-induced LIPSS are revisited and an explanation is proposed why HSFL are observed predominantly in the subpicosecond range for below band-gap excitation of dielectrics and semiconductors.
Swift heavy ion induced surface modification for tailoring coercivity in Fe–Ni based amorphous thin films
Authors: Thomas Senoy , Thomas Hysen , Avasthi D. K. , Tripathi A. , Ramanujan R. V. , Anantharaman M. R.
Published: February 2009

Fe–Ni based amorphous thin films were prepared by thermal evaporation. These films were irradiated by 108 MeV Ag8+ ions at room temperature with fluences ranging from 1×1012 to 3×1013 ions/cm2 using a 15 UD Pelletron accelerator. Glancing angle x-ray diffraction studies showed that the irradiated films retain their amorphous nature. The topographical evolution of the films under swift heavy ion (SHI) bombardment was probed using atomic force microscope and it was noticed that surface roughening was taking place with ion beam irradiation. Magnetic measurements using a vibrating sample magnetometer showed that the coercivity of the films increases with an increase in the ion fluence. The observed coercivity changes are correlated with topographical evolution of the films under SHI irradiation. The ability to modify the magnetic properties via SHI irradiation could be utilized for applications in thin film magnetism.
Asymmetric magnetoimpedance in self-biased layered CoFe/CoNi microwires
Authors: Torrejón J. , Vázquez M. , Panina L. V.
Published: February 2009

The magnetoimpedance (MI) effect has been investigated in a family of multilayer microwires with biphase magnetic behavior consisting of a soft nucleus (CoFeSiB), an intermediate nonmagnetic insulating layer, and a hard outer shell (CoNi). The MI response of the soft phase can be tailored by its magnetostatic coupling with the hard phase. The hard outer shell, in its remanence state, creates a bias field in the soft nucleus that shifts the magnetization process and results in an asymmetric MI response. The amplitude of that bias field is determined by the geometric characteristics and the magnetic state of the hard phase. Furthermore, a near linear MI behavior with high sensitivity was realized around zero operation field point, with the advantage of not employing external biasing fields and additional coils. This makes biphase microwires exhibiting self-bias and asymmetric MI very attractive as sensing elements in magnetic-field sensor devices and materials.
Reversible surface morphology in shape-memory alloy thin films
Authors: Wu M. J. , Huang W. M. , Fu Y. Q. , Chollet F. , Hu Y. Y. , Cai M.
Published: February 2009

Reversible surface morphology can be used for significantly changing many surface properties such as roughness, friction, reflection, surface tension, etc. However, it is not easy to realize atop metals at micron scale around ambient temperature. In this paper, we demonstrate that TiNi and TiNi based (e.g., TiNiCu) shape-memory thin films, which are sputter-deposited atop a silicon wafer, may have different types of thermally-induced reversible surface morphologies. Apart from the well-known surface relief phenomenon, irregular surface trenches may appear in the fully crystallized thin films, but disappear upon heating. On the other hand, in partially crystallized thin films, the crystalline structures (islands) appear in chrysanthemum-shape at high temperature; while at room temperature, the surface morphology within the islands changes to standard martensite striations. Both phenomena are fully repeatable upon thermal cycling. The mechanisms behind these phenomena are investigated.
Control of chaotic and deterministic magnetization dynamics regimes by means of sample shape varying
Authors: Vagin D. V. , Polyakov O. P.
Published: February 2009

Effect of demagnetization field on chaotic and deterministic nonlinear magnetization dynamics regimes formation in the presence of oscillating and constant external magnetic fields is studied using the Landau–Lifshitz–Gilbert approach. The uniformly magnetized sample is considered to be an axially symmetric particle described by demagnetization factors and to have uniaxial crystallographic anisotropy formed some angle with an applied field direction. The equations of magnetic moment motion are considered to be the synergetic equations and the system behavior is examined on the phase plane. It is investigated as to how the change in particle shape and its orientation with respect to the external field (system’s configuration) can cause the transition between chaos and regular magnetization dynamics. Moreover, the way to completely suppress chaotic dynamics of magnetic moments in such sample is proposed. To produce a regular study, all results are presented in the form of bifurcation diagrams for all sufficient dynamics regimes of the considered system. Our results suggest that varying the particle’s shape and fields’ geometry may provide a useful way of magnetization dynamics control in complex magnetic systems.
Domain stabilization effect of interlayer on ferroelectric poly(vinylidene fluoride-trifluoroethylene) copolymer ultrathin film
Authors: Xu Haisheng , Liu Xiaobing , Fang Xuerang , Xie Haifen , Li Guobing , Meng Xiangjian , Sun Jinglan , Chu Junhao
Published: February 2009

A charge injection material, poly(3,4-ethylene dioxythioohene)-poly(styrene sulfonic) acid, is introduced as a buffer layer between metal electrodes and a ferroelectric poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer ultrathin film. The buffer layer not only prevents the reactions between P(VDF-TrFE) layer and the top electrode during metallization process, which leads to the loss of polarization, but also supplies the amount of charges needed for compensation of the ferroelectric dipoles to stabilize the domain during switching process so that the fatigue property was improved tremendously. The sandwiched structure shows prominent ferroelectric properties in a 50 nm P(VDF/TrFE) film. A coercive electric field of 52 MV/m and a remnant polarization of 88 mC/m2 are recorded. With two additional organic interlayers, 33 nm thick in total, the coercive field decreases. After more than 1×107 cycles of switching, the polarization remains as high as 68 mC/m2. Moreover, the cell still has good ferroelectric properties at 60 °C. Even as the thickness of P(VDF/TrFE) film is down to 25 nm, a remnant polarization of 54 mC/m2 is obtained.
Regular and chaotic dynamics of magnetization precession in ferrite–garnet films
Authors: Shutyĭ Anatoliy M. , Sementsov Dmitriy I.
Published: February 2009

By numerically solving equations of motion and constructing the spectrum of Lyapunov exponents, nonlinear dynamics of uniformly precessing magnetization in (110) thin film structures with perpendicular magnetic bias is investigated over a wide frequency range of the alternating field. Bifurcational changes in magnetization precession and the states of dynamical bistability are discovered. Conditions for the realization of high-amplitude regular and chaotic dynamic regimes are revealed. The possibility of controlling those precession regimes by using external magnetic fields is shown. The features of time analogs of the Poincaré section of trajectories in the chaotic regimes are studied.
Magnetoelectric coupling induced by exchange striction in frustrated Ising spin chain: Monte Carlo simulation
Authors: Yao Xiaoyan , Lo Veng Cheong , Liu Jun-Ming
Published: February 2009

The fascinating magnetoelectric behavior as observed in Ca3CoMnO6 compound [Choi et al., Phys. Rev. Lett. 100, 047601 (2008)] is investigated by using Monte Carlo simulation based on a one-dimensional elastic Ising model. The macroscopic polarization results from the ionic displacements attributed to the exchange striction in an up-up-down-down (↑↑↓↓) spin ordering. In this scenario, the microscopic structures of spin and ionic displacement are investigated at different temperatures under different external electric fields to illuminate in detail the microscopic mechanism of the strong coupling between the magnetism and the ferroelectricity. It is revealed that the change in spin configuration dependent on temperature induces the freezing and melting phenomena of the polarized domains and thus the complicated temperature-dependent ferroelectric behavior in the whole low temperature range, namely the decline of the macroscopic polarization and the broad peak of dielectric constant. On the other hand, an external electric field also has influence on the magnetic structure through affecting the ionic displacements.
Size-dependent magnetic properties of high oxygen content YMn2O5±δ multiferroic nanoparticles
Authors: Ma C. , Yan J.-Q. , Dennis K. W. , McCallum R. W. , Tan X.
Published: February 2009

The effect of particle size on magnetic properties in single-crystalline multiferroic YMn2O5.07 nanoparticles was investigated. A modified Pechini’s method was employed to synthesize YMn2O5.07 powders with different particle sizes under an atmosphere of 10 bar O2. It was found that the multiferroic YMn2O5.07 compound displays a profound size dependence in its magnetic properties when the particles were smaller than 160 nm. With a decrease in particle size, a ferromagnetic-like phase with a broad transition emerges and the transition temperature increases. This ferromagnetic-like phase might be attributed to the surface layer of the nanoparticles and the broad magnetic transition could be caused by the dispersion of particle size and the size dependence of the transition temperature.
Enhanced luminescence through ion-doping-induced higher energy phonons in GdTaO4:Eu3+ phosphor
Authors: Liu Bo , Gu Mu , Liu Xiaolin , Han Kun , Huang Shiming , Ni Chen , Zhang Guobin , Qi Zeming
Published: February 2009

The photoluminescence enhancement effect of Li-, Zn-, or Al-doped GdTaO4:Eu3+ is investigated at 20 and 295 K. The underlying reason of luminescence enhancement by ion doping is revealed, and a mechanism of the enhancement based on the temperature effect is proposed. It can be safely concluded that the photoluminescence enhancement effect originates from temperature enhancement effect, which can be further strengthened by ion-doping-induced higher energy phonons, which are demonstrated by infrared transmittance spectra. This can reasonably explain why the photoluminescence is remarkably enhanced by ion-doping in GdTaO4:Eu3+ phosphor at 295 K rather than at 20 K.