bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of prolactin in nuclear maturation and ovulation in amphibian oocytes
Authors: Ramos Inés , Cisint Susana , Medina Marcela F. , Crespo Claudia A. , Fernández Silvia N.
Published: September 2005

The present study was undertaken to determine the effect of prolactin (Prl) on Bufo arenarum oocyte maturation and ovulation, two characteristic events of the breeding period, the stage of the sexual cycle in which gamete growth is complete. We observed that Prl, at the doses assayed, did not affect nuclear maturation per se. In addition, when follicles were pretreated with Prl and progesterone was later added to the medium as a physiological nuclear maturation inducer, the percentage of germinal vesicle breakdown obtained with the steroid was unaffected by Prl. The analysis of the in vitro ovulation process demonstrated that pituitary homologous homogenate (PHH) produced a dose- and month-dependent stimulating effect. The maximum percentage of ovulated oocytes was obtained from the end of July to October, the period in which oviposition naturally occurs. Prl by itself did not affect the ovulation process, but when both the hormone and PHH were present in the incubation medium, a significant increase in ovulated oocytes was observed. The results suggest that Prl does not participate in oocyte maturation; however, its presence in the incubation medium would increase oocyte sensitivity to the action of the physiological ovulation inducers.
On the origin and configuration of the 20 March 2003 interplanetary shock and magnetic cloud at 1 AU
Authors: Berdichevsky D. B. , Richardson I. G. , Lepping R. P. , Martin S. F.
Published: September 2005

On 20 March 2003, a forward shock was observed in the near‐Earth solar wind, followed 8 hours later by an interplanetary magnetic cloud (IMC), in a configuration having several uncommon features: Both were parts of a 38‐hour interval containing transient solar outflows that occurred in an extended high‐speed stream from a Y‐shaped extension of the south polar coronal hole. (In contrast, IMCs, and ejecta in general, were rarely observed within high‐speed streams at low heliolatitudes during cycle 23.) The most likely solar source for the IMC is AR 10314, located at S15°, just above the “fork” of the Y‐shaped coronal hole. Several solar flares occurred in this active region on 17–18 March, as well as a succession of four coronal mass ejections (CMEs). Velocity considerations narrow the most likely source of the 38‐hour interval of activity to two CMEs on 17 March 2003 associated with solar flares at W33° and W39°. The IMC axis had a north‐south orientation, which is unusual for IMCs during this solar cycle. Its left‐handedness implies an association with a left‐skewed coronal arcade, which is less common in the Southern Hemisphere. Considering the shock observed ahead of the IMC, we conclude based on orientation and ram pressure arguments that this shock was not driven by the IMC, as might be presumed, but was the flank of an unrelated shock that overtook the IMC approximately halfway between Sun and Earth, heating the plasma and accelerating particles within the IMC. The CME associated with the X‐class flare, at 1208 UT on 18 March in AR 10314 appears to be the solar source for this shock.
Electromagnetic bias at off‐nadir incidence angles
Authors: Millet Floyd W. , Warnick Karl F. , Arnold David V.
Published: September 2005

Measurements of the electromagnetic (EM) bias in altimeter sea surface ranges at nadir and off‐nadir incidence angles were made during the Brigham Young University (BYU) Off‐Nadir Experiment (Y‐ONE) in the months of March and April, 2003. Tower‐mounted C‐ and Ku‐band radars were deployed along with laser rangefinders and a weather station to measure sea surface profiles and environmental parameters. The incidence angle range was nadir to 17°. An off‐nadir bias model incorporating the effects of hydrodynamic modulation of short waves and tilt modulation of long waves was also developed. Both the experimental data set and the theoretical model led to a bias of decreasing magnitude as the incidence angle moves away from nadir. The average measured EM bias at C‐band was approximately zero at 14° incidence, and a small positive mean bias (1% SWH) was observed at 17°. By extrapolating from the Ku‐band measurements, the mean bias vanished at 18.5° for the higher frequency.
Causes of large‐scale sea level variations in the Southern Ocean: Analyses of sea level and a barotropic model
Authors: Vivier Frédéric , Kelly Kathryn A. , Harismendy Migel
Published: September 2005

We analyze a decade of sea surface height (SSH) measurements in the Southern Ocean from the TOPEX/Poseidon and ERS altimeters, with a focus on the variability at timescales <2 years. Among the different processes contributing to large‐scale SSH variations, the barotropic response to the winds dominates poleward of 50°S, while thermosteric processes dominate equatorward, except for resonant basins for the barotropic modes and regions of intense eddy activity. A finite element barotropic model has been developed to analyze the vorticity budget. The SSH from the model agrees well with observations. The leading barotropic mode, which is annular and is confined near Antarctica, is responsible for most of the barotropic circumpolar transport. It is coherent with the zonally integrated eastward wind stress consistent with a free mode response. Although previously evidenced in bottom pressure data, this mode is only partially seen in altimeter data because of ice coverage. It nevertheless distinctly appears above the Pacific ridges where it expands meridionally up to midlatitudes. In the rest of the domain, several regions coherent with the local wind stress curl are found. These are regions isolated by f/H contours, mostly deep basins. An analysis of the vorticity budget shows that, generally, topographic Sverdrup balance is the leading process for periods ≥50 days, but in some regions (resonant basins), diffusive and nonstationary terms are important. A model experiment shows that transients redistribute energy along f/H waveguides, contributing to drain resonant regions, as was hypothesized in previous works.
Wavelet and scaling analysis of monthly precipitation extremes in Germany in the 20th century: Interannual to interdecadal oscillations and the North Atlantic Oscillation influence
Authors: Markovic D. , Koch M.
Published: September 2005

Monthly precipitation extremes from gauging stations across Germany were studied using continuous wavelet tools toward variance and frequency‐time localization and detection of dominant oscillations. Apart from the high‐frequency, 1 year oscillation, the monthly precipitation extremes show enhanced power at interannual (7‐8 years) and/or interdecadal (11‐14 years) low‐frequency scales, in particular in the second part of the 20th century, providing evidence for some regional climatic changes over Germany. Applying detrended fluctuation analysis (DFA), scaling properties of the precipitation time series through the computation of the Hurst parameter are determined. It is apparent that data with low‐frequency components, regardless of whether significant or not, show higher Hurst parameter values, that is, some amount of persistence, than data without such components. Through analyses of the scale‐averaged wavelet power and the cross‐wavelet spectra, evidence for a teleconnective influence of the North Atlantic Oscillation on the precipitation pattern, primarily over the last 40 years, and with partly opposite effects in the northern and southern parts of Germany, is found. As such, the North Atlantic Oscillation phase of enhanced decadal variability was shown to be responsible for the low‐frequency precipitation components.
Effects of simulated natural variability on Arctic temperature projections
Authors: Sorteberg Asgeir , Furevik Tore , Drange Helge , Kvamstø Nils Gunnar
Published: September 2005

A five‐member ensemble with a coupled atmosphere‐sea ice‐ocean model is used to examine the effects of natural variability on climate projections for the Arctic. The individual ensemble members are initialized from a 300 years control experiment, each starting from different strengths and phases of the Atlantic Meridional Overturning Circulation. The ensemble members are integrated for 80 years with a 1% per year increase in the atmospheric concentration of CO2. The main findings are that on decadal time scales, multi‐model spread of estimated temperature changes in the Arctic may potentially be attributed to internal variability of the climate system. During weak CO2 forcing the internal variability may mask the strength of the anthropogenic signals for several decades. The implications of the findings are that attribution of any Arctic climate change trends calculated over a few decades is difficult.
Estimating atmospheric CO2 from advanced infrared satellite radiances within an operational four‐dimensional variational (4D‐Var) data assimilation system: Results and validation
Authors: Engelen Richard J. , McNally Anthony P.
Published: September 2005

More than a year of Atmospheric Infrared Sounder (AIRS) radiance observations have been assimilated in the European Centre for Medium‐Range Weather Forecasts four‐dimensional variational (4D‐Var) data assimilation system to estimate tropospheric CO2. The assimilation of a set of 18 spectral channels provides a mean tropospheric mixing ratio representing a layer between ∼700 hPa and the tropopause. Analysis errors for a 5‐day mean on a 6° by 6° averaging grid box are on the order of 1%. Comparisons with independent flight data from Japanese Airlines and National Oceanic and Atmospheric Administration Climate Monitoring and Diagnostics Laboratory are favorable. Differences between the averaged assimilation estimates and the onboard flask observations are generally within the 1‐σ error bars. Currently, this work is being extended by introducing CO2 as a full assimilation model tracer variable, which will allow the operational monitoring of atmospheric CO2 using AIRS observations and observations from upcoming instruments.
Complex Adaptive Systems in the Behavioral and Social Sciences
Authors: Eidelson Roy J.
Published: September 2005

This article examines applications of complexity theory within the behavioral and social sciences. Specific attention is given to the fundamental characteristics of complex adaptive systems (CAS)—such as individuals, groups, and societies—including the underlying structure of CAS, the internal dynamics of evolving CAS, and how CAS respond to their environment. Examples drawn from psychology, sociology, economics, and political science include attitude formation, majority–minority relations, social networks, family systems, psychotherapy, norm formation, organizational development, coalition formation, economic instabilities, urban development, the electoral process, political transitions, international relations, social movements, drug policy, and criminal behavior. The discussion also addresses the obstacles to implementing the CAS perspective in the behavioral and social sciences and implications for research methodology.
Between Psoriasis and Ptarmigan: American Encyclopedia Portrayals of Psychology, 1880–1940
Authors: Benjamin Ludy T. , Bryant William H. M. , Campbell Catherine , Luttrell Jolynn , Holtz Cynthia
Published: September 2005

Articles in encyclopedias represented 1 of several avenues that the new experimental psychologists of the late 19th and early 20th centuries had to portray their science to the public, and as such, these entries are important documents in understanding the agenda of the psychologist authors and the bases for the public's understanding of psychology. This article describes a content analysis of the psychology entries from 174 American encyclopedias published between 1880 and 1940. The analysis focuses on the changes in this content over time and the correspondence of those changes to the evolution of American psychology. The data show that the encyclopedia entries were slow in reporting changes in psychology and often promoted a singular view of the subject matter of psychology.
Pursuing Unity in a Fragmented Psychology: Problems and Prospects
Authors: Yanchar Stephen C. , Slife Brent D.
Published: September 2005

Many psychologists are concerned that disciplinary fragmentation is precluding the accumulation of knowledge and catalyzing the dissolution of institutionalized psychology. Herein the authors review prominently discussed causes of fragmentation and the solutions thus far tendered. Their review suggests that fragmentation pervades the discipline at many levels and that numerous, competing solutions to the problem of fragmentation have failed to promote unity. The authors suggest that 3 key questions must be answered before a tenable unification strategy can be formulated. Answers to these questions will provide a common starting point for discussing the problems and prospects of unification and for evaluating specific unification strategies.
A Person–Process–Context–Time Approach to Understanding Intellectual Development
Authors: Williams Wendy M. , Ceci Stephen J.
Published: September 2005

We argue that scientific psychology's twin foci on biology (person) and process can benefit from a broadening. Specifically, we show that including two additional foci—context and time—can add explanatory leverage to both the design and interpretation of scientific studies. We focus on research on intellectual development to illustrate our points. First, we briefly describe each of the four factors (person, process, context, and time), and we review studies that focus on each individual factor and its role in intellectual development. Next, we review studies that focus simultaneously on multiple factors. We illustrate how multifactor approaches reveal fine-grained differentiations that are not reducible to single factors. Finally, we describe a study that considers simultaneously all four factors, and we show how omitting any one of these factors from the design and analysis changes the interpretation of the data.
Relational Schemas as a Source of If–Then Self-Inference Procedures
Authors: Baldwin Mark W.
Published: September 2005

It is generally accepted that the sense of self is constructed rather than directly perceived or experienced. The hypothesis is advanced here that people's rules of self-inference derive in large part from if–then expectancies about the contingencies of interpersonal interaction; that is, expectancies about how other people will react to one's behaviors. If so, a central type of cognitive structure contributing to self-construal is the relational schema, representing regularities in interaction. Research examining the cognitive representation of interpersonal expectancies, the activation of those representations, and the effects on self-experience is described.
Mental Representations in Personality Development, Psychopathology, and the Therapeutic Process
Authors: Blatt Sidney J. , Auerbach John S. , Levy Kenneth N.
Published: September 2005

This article considers the construct of mental representation from the perspectives of psychoanalytic object-relations theory and cognitive developmental psychology and the congruence of these formulations with research and theory in cognitive science and social cognition. Concepts of mental representation are applied to the study of psychopathology, personality assessment, interpersonal relationships or attachment styles, and therapeutic progress in the long-term, inpatient treatment of seriously disturbed adolescents and young adults. Understanding of personality development, psychopathology, and the therapeutic process is greatly enhanced by this constructivist perspective, which considers the construction of mental representations or cognitive–affective schemas to be a central constituent of personality development and organization.
The Social–Cognitive Construction of Psychotherapeutic Change: Bridging Social Constructionism and Cognitive Constructivism
Authors: Martin Jack , Sugarman Jeff
Published: September 2005

Self-with-other processing and construction play an important role in human adjustment, development, and change. This idea is critical for an adequate understanding of psychotherapy and psychotherapeutic change. A theory of psychotherapeutic change that combines elements of both social constructionist and cognitive constructivist thought is presented briefly. After reviewing salient examples of both forms of thought as these have manifested in theorizing about psychotherapeutic change, a sampling of original empirical demonstrations is offered in support of the theory. Psychotherapeutic change is described as a process of appropriation and practical application through which clients internalize therapeutic conversations and activities, which they then use as psychological tools to restructure personal theories, experiences, and actions.
Structural Dynamism in the Concept of Self: A Flexible Model for a Malleable Concept
Authors: DeSteno David , Salovey Peter
Published: September 2005

The self-concept is theorized to play an important role in many psychological processes. Numerous theories rest on assumptions concerning the differential accessibility of pieces of self-knowledge, but relatively little attention during the past decade has centered on examining the underlying structure of the self-concept that mediates such differences. In the present article, we suggest a new model of the self-concept that incorporates recent advances in knowledge regarding conceptual structure. We envision the self as a representation in working memory with inherently flexible content and organization. Initial empirical evidence supporting this view is reviewed and followed by a discussion of the implications of this model for many phenomena involving the self-concept.
The Psychology of Science: Review and Integration of a Nascent Discipline
Authors: Feist Gregory J. , Gorman Michael E.
Published: September 2005

Disciplines that study science are relatively well established in philosophy, history, and sociology. Psychology of science, by comparison, is a late bloomer but has recently shown signs of codification. The authors further this codification by integrating and reviewing the growing literature in the developmental, cognitive, personality, and social psychology of science. Only by integrating the findings from each of these perspectives can the basic questions in the study of scientific behavior be answered: Who becomes a scientist and what role do biology, family, school, and gender play? Are productivity, scientific reasoning, and theory acceptance influenced by age? What thought processes and heuristics lead to successful discovery? What personality characteristics distinguish scientists from nonscientists and eminent from less eminent scientists? Finally, how do intergroup relations and social forces influence scientific behavior? A model that integrates the consensual empirical findings from the psychology of science is proposed.
Overview to Special Issue: Understanding Emotions Means Crossing Boundaries within Psychology
Authors: Rosenberg Erika L. , Fredrickson Barbara L.
Published: September 2005

Emotional processes influence a wide range of mental and physical systems, which makes them difficult to understand from a single perspective. In this special issue of the Review of General Psychology, contributing authors present 4 articles that draw from several areas within psychology in the service of understanding a topic relevant to emotion. In this overview, the authors argue that the long neglect of the scientific study of complex processes such as emotion might be linked, in part, to the fractionation of the field into specialized subdisciplines. Just as emotions were of central concern in the early years of psychology (which was a generalist's era), as psychology moves toward more integration in the late 20th century broad phenomena such as emotions are once again central interests. The 4 articles of this special issue are briefly reviewed as exemplars of an integrated approach to understanding emotional phenomena.
Emotion, Social Function, and Psychopathology
Authors: Keltner Dacher , Kring Ann M.
Published: September 2005

The studies of emotion function and emotional disorders complement one another. In this article, the authors outline relations between the social functions of emotion and four psychological disorders. The authors first present a social-functional account of emotion and argue that emotions help coordinate social interactions through their informative, evocative, and incentive functions. They then review evidence concerning the emotional and social problems related to depression, schizophrenia, social anxiety, and borderline personality disorder and consider how the emotional disturbances related to these disorders disrupt interactions and relationships, thus contributing further to the maintenance of the disorder. They conclude by discussing research strategies relevant to the study of emotion, social interaction, and psychopathology.
Initial stages of water adsorption on NaCl (100) studied by scanning polarization force microscopy
Authors: Verdaguer Albert , Sacha G. M. , Luna M. , Frank Ogletree D. , Salmeron Miquel
Published: September 2005

Scanning polarization force microscopy was used to study the topography, polarizability, and contact potential of cleaved NaCl(100) as a function of the relative humidity (RH) between <5% and 40%. In this humidity range there are reversible changes in surface potential and polarizability, while large scale modifications in step topography and irreversible ion redistribution occur above 40% RH. In dry conditions the surface contact potential was more negative near atomic steps than over flat terraces. As humidity was increased, changes were observed in the local polarizability of the steps due to ionic solvation, and the contact potential of the terraces became more negative. At 40% RH surface-potential differences between steps and terraces could no longer be detected. These results are interpreted in terms of preferential anion solvation, initially localized near steps, and later spreading over the entire surface.
Photodissociation dynamics of indole in a molecular beam
Authors: Lin Ming-Fu , Tseng Chien-Ming , Lee Yuan T. , Ni Chi-Kung
Published: September 2005

Photodissociation of indole at 193 and 248 nm under collision-free conditions has been studied in separate experiments using multimass ion imaging techniques. H atom elimination was found to be the only dissociation channel at both wavelengths. The photofragment translational energy distribution obtained at 193 nm contains a fast and a slow component. Fifty-four percent of indole following the 193 nm photoexcitation dissociate from electronically excited state, resulting in the fast component. The rest of 46% indole dissociate through the ground electronic state, giving rise to the slow component. A dissociation rate of 6×105s−1, corresponding to the dissociation from the ground electronic state, was determined. Similar two-component translational energy distribution was observed at 248 nm. However, more than 80% of indole dissociate from electronically excited state after the absorption of 248 nm photons. A comparison with the potential energy surfaces from the ab initio calculation has been made.
Unisized two-dimensional platinum clusters on silicon(111)-7×7 surface observed with scanning tunneling microscope
Authors: Yasumatsu Hisato , Hayakawa Tetsuichiro , Koizumi Shin’ichi , Kondow Tamotsu
Published: September 2005

Uni-sized platinum clusters (size range of 5–40) on a silicon(111)-7×7 surface were prepared by depositing size-selected platinum cluster ions on the silicon surface at the collision energy of 1.5 eV per atom at room temperature. The surface thus prepared was observed by means of a scanning tunneling microscope (STM) at the temperature of 77 K under an ambient pressure less than 5×10−9Pa. The STM images observed at different cluster sizes revealed that (1) the clusters are flattened and stuck to the surface with a chemical-bond akin to platinum silicide, (2) every platinum atom occupies preferentially the most reactive sites distributed within a diameter of ∼2nm on the silicon surface at a cluster size up to 20, and above this size, the diameter of the cluster increases with the size, and (3) the sticking probability of an incoming cluster ion on the surface increases with the cluster size and reaches nearly unity at a size larger than 20.
Low-frequency Raman scattering of Ge and Si nanocrystals in silica matrix
Authors: Yang Y. M. , Wu X. L. , Yang L. W. , Huang G. S. , Siu G. G. , Chu Paul K.
Published: September 2005

Ge and Si nanocrystals (nc-Ge and nc-Si) with average sizes in the range of 2–7nm, embedded in silica matrix, were fabricated for investigating their acoustic-phonon vibrational properties. The freely elastic sphere theory was found to be unsuitable for explaining the low-frequency phonon vibration character of both nc-Ge and nc-Si in our current experiments. We have assigned the observed low-frequency Raman peaks to “LA-like mode” and “TA-like mode” in terms of their polarization and depolarization behaviors. In addition, it is revealed that the lattice contraction phenomenon exists in nc-Ge and nc-Si with sizes smaller than 4nm, which leads to a contrary effect against matrix traction on the phonon vibrational frequencies.
Bond selective dissociative electron attachment to thymine
Authors: Ptasińska S. , Denifl S. , Mróz B. , Probst M. , Grill V. , Illenberger E. , Scheier P. , Märk T. D.
Published: September 2005

Free-electron attachment to thymine and partially deuterated thymine, where D replaces H at all carbon atoms, is studied in the electron energy range from about 0to15eV. The formation of fragment anions that are formed by the loss of one or two H (D) atoms is analyzed as a function of the incident electron energy using a crossed electron/neutral beam apparatus in combination with a quadrupole mass spectrometer. By using partially deuterated thymine and quantum-chemical calculation a bond selectivity for the loss of one and two hydrogen atoms is observed that is determined only by the kinetic energy of the incident electron.
The Gray-Scott model under the influence of noise: Reentrant spatiotemporal intermittency in a reaction-diffusion system
Authors: Hayase Yumino , Brand Helmut R.
Published: September 2005

We investigate the influence of noise on the spatiotemporal behavior of the Gray-Scott model, a prototype for a simple reaction-diffusion system. In the parameter regime studied it is characterized deterministically by a stable fixed point. As the noise increases a regular periodic pattern is replaced first by an irregularly oscillating periodic pattern and then by spatiotemporal intermittency. With further increasing noise strength the spatiotemporal intermittency is first replaced by a low amplitude noisy regime followed by spatiotemporal intermittency (STI) embedded into a noisy background. At sufficiently high noise intensity high amplitude noise prevails. We point out that the transition from spatiotemporal intermittency to low amplitude noise can be traced back to the fact that the spatially homogeneous state is a global attractor. As the noise strength grows further the “noisy” fixed point starts to communicate with STI leading to noise-induced spatiotemporal intermittency as an excitable state. At high enough noise strength high amplitude noise is left over wiping out all details of the underlying deterministic dynamical system.
The influence of the quencher concentration on the rate of simple bimolecular reaction: Molecular dynamics study
Authors: Litniewski Marek
Published: September 2005

The paper presents the results of large-scale molecular dynamics simulations of the irreversible bimolecular reaction A+B→C+B for the simple liquid composed of mechanically identical soft spheres. The systems with the total number of molecules corresponding to 107–109 are considered. The influence of the concentration of a quencher (B) on the surviving probability of A and the reaction rate is analyzed for a wide range of the concentrations and for two significantly different reduced densities. It is shown that the quencher concentration dependence effect (QCDE) is, in fact, a composition of two QCDE effects: the short-time QCDE that increases the reaction rate and the long-time QCDE that decreases it. The paper also analyzes the influence of the concentration on the steady-state rate constant, kSS, obtained by integrating the surviving probability. The excess in kSS due to finite quencher concentration changes the sign from negative to positive while going from low to high concentrations. Generally, the excess is extremely weak. It attains a 1% level only if the concentration is very high.
Conditions for the fast reconnection mechanism in three dimensions
Authors: Ugai M. , Zheng L.
Published: September 2005

Physical conditions for the fast reconnection mechanism to be realized as an eventual solution of magnetohydrodynamic equations are examined by three-dimensional (3D) simulations for different resistivity models. Initiated by a small disturbance in a current sheet, all the phenomena grow by the self-consistent interaction between the 3D reconnection flow and the effective resistivity. For the classical resistivity η due to Coulomb collisions, where η∝T−3∕2, no effective reconnection occurs, since the resistivity becomes reduced with the increase in temperature T as magnetic reconnection proceeds, which indicates the negative feedback between the reconnection flow and the resistivity. For the anomalous resistivity, where η increases with the current density when a threshold is exceeded, the positive feedback eventually leads to the fast reconnection mechanism as a nonlinear instability. In this case, the resistivity is distinctly enhanced at the slow shock layer attached to the diffusion region, so that the shock layer becomes thicker, and resistive tearing is more likely to take place in the diffusion region. For the anomalous resistivity, where η increases with the relative electron-ion drift velocity when a threshold is exceeded, the fast reconnection mechanism evolves most effectively as a nonlinear instability and is sustained steadily. It is concluded in general three-dimensional situations that the fast reconnection mechanism can be realized as an eventual solution for current-driven anomalous resistivities, whereas in usual circumstances with the classical resistivity no substantial magnetic reconnection takes place.
ac impedance techniques to study oxidation process of tunnel barriers in CoFe–AlOx–CoFe magnetic tunnel junctions
Authors: Huang J. C. A. , Hsu C. Y.
Published: September 2005

The complex impedance spectra of CoFe–AlOx–CoFe tunnel junctions with under-, proper-, and overoxidized tunnel barriers have been investigated by ac impedance techniques. Two sets of parallel resistance (R) and capacitance (C) elements and a R element in series, modeling the impedance contributions of the metal-oxide interfaces and bulk insulating layers, are employed to describe the impedance spectra of under- and proper-oxidized junctions. This model, however, reveals a discrepancy for overoxidized junctions. This discrepancy can be reconciled by including a third set of parallel RC element, which suggests the appearance of overoxidized CoFeOx layer upon the bottom electrode. From further analysis of interfacial capacitance as a function of oxidation time, the bottom interfacial capacitance widely diverges from the top interfacial capacitance and can be related to the oxidation process of tunnel barrier. The analyzing results of impedance technique are also consistent with the results by complex capacitance technique.
Magnetic and magnetoresistance properties of spin valves using epitaxial Fe3O4 (110) as the pinning layer
Authors: Matsuda Hiroshi , Okamura Soichiro , Shiosaki Tadashi , Adachi Hideaki , Sakakima Hiroshi
Published: September 2005

Magnetic and magnetoresistance (MR) properties of spin valves composed of Co∕Cu∕Co∕iron oxide layer were studied using epitaxial Fe3O4 (110) grown on MgO (110) as the pinning layer. It was confirmed from the in-plane magnetization curves that the epitaxial Fe3O4 (110) films have the easy axes along the ⟨110⟩ direction and the hard axes along the ⟨001⟩ direction. The spin valves composed of Co∕Cu∕Co∕Fe3O4 (110) showed quite different MR curves depending upon the direction of the magnetic field applied in the plane of Fe3O4 (110). Butterflylike MR curves, which imply the difference in the coercive fields between the top and bottom Co layers, were observed when the field was applied along the ⟨001⟩ direction of Fe3O4. On the other hand, flat MR curves, which implied the difference of the saturation fields between top and bottom Co, were observed when the field was applied along the ⟨110⟩ direction of Fe3O4. The magnetization easy axis of Co layers might be perpendicular to that of Fe3O4. These magnetic and MR properties could be explained by assuming the 90° coupling between the bottom Co and the Fe3O4 layers, and the ferromagnetic coupling (so-called Néel-type coupling) between the top and bottom Co layers.
Studies on the response of resistive-wall modes to applied magnetic perturbations in the EXTRAP T2R reversed field pinch
Authors: Gregoratto D. , Drake J. R. , Yadikin D. , Liu Y. Q. , Paccagnella R. , Brunsell P. R. , Bolzonella T. , Marchiori G. , Cecconello M.
Published: September 2005

Arrays of magnetic coils and sensors in the EXTRAP T2R [P. R. Brunsell et al., Plasma Phys. Controlled Fusion 43 1457 (2001)] reversed-field pinch have been used to investigate the plasma response to an applied resonant magnetic perturbation in the range of the resistive-wall modes (RWMs). Measured RWM growth rates agree with predictions of a cylindrical ideal-plasma model. The linear growth of low-n marginally stable RWMs is related to the so-called resonant-field amplification due to a dominant ∣n∣=2 machine error field of about 2 G. The dynamics of the m=1 RWMs interacting with the applied field produced by the coils can be accurately described by a two-pole system. Estimated poles and residues are given with sufficient accuracy by the cylindrical model with a thin continuous wall.
Fast terahertz detectors with spectral tunability based on quantum Hall Corbino devices
Authors: Stellmach C. , Hirsch A. , Nachtwei G. , Vasilyev Yu. B. , Kalugin N. G. , Hein G.
Published: September 2005

We present THz photoconductivity measurements on Corbino-shaped GaAs∕AlGaAs heterostructures. The THz source is a pulsed p-Ge laser, which provides photon frequencies of 1.7THzto2.5THz (corresponding to wavelengths of 180–120μm). We investigate the relaxation process from the dissipative state to the quantum Hall state time-resolved and find that the relaxation time depends on the applied voltage and on the mobility of the sample. Relaxation times of approximately 10ns to over 200ns are observed. A simple picture is suggested to explain the results. In addition, spectrally resolved measurements are discussed. The short response time and the useful spectral selectivity together with the high sensitivity make QH devices promising for high-performance THz detectors.
High-electron-mobility AlGaN∕GaN heterostructures grown on Si(001) by molecular-beam epitaxy
Authors: Joblot S. , Semond F. , Cordier Y. , Lorenzini P. , Massies J.
Published: September 2005

The growth of AlGaN∕GaN heterostructure on Si (001) substrates by molecular-beam epitaxy using ammonia as nitrogen precursor is reported. The structural, optical, and electrical properties of such heterostructures are assessed. It is shown that a two-dimensional electron gas is formed at the Al0.23Ga0.77N∕GaN interface. This type of heterostructure exhibits a sheet carrier density of 4.2×1012cm−2 with a mobility of 730cm2∕Vs at room temperature. Preliminary results concerning high-electron-mobility-transistor static characteristics are presented.
Strong directional dependence of single-quantum-dot fine structure
Authors: Stevenson R. Mark , Young Robert J. , See Patrick , Norman Carl E. , Shields Andrew J. , Atkinson Paola , Ritchie David A.
Published: September 2005

By isolating quantum dots in microstructures with cleaved facets, we measure individual-quantum-dot photoluminescence emitted in the in-plane direction, in addition to the widely studied vertical direction. The emission is shown to be polarized in the plane, and the observed fine structure is found to be extremely directionally-dependent. These characteristics are attributed to exciton states with orthogonally aligned dipoles in the plane. The result suggests possibilities for single-quantum-dot devices, including side-emitting single-photon sources.
Electrical properties of ultrathin HfO2 films for replacement metal gate transistors, fabricated by atomic layer deposition using Hf(N(CH3)(C2H5))4 and O3
Authors: Kamiyama Satoshi , Miura Takayoshi , Nara Yasuo
Published: September 2005

Ultrathin HfO2 gate dielectric was fabricated by atomic layer deposition (ALD) technology using tetrakis(ethylmethylamino)hafnium {Hf[N(CH3)(C2H5)]4}, with O3 as an oxidant for use in replacement metal gate transistors. From secondary ion mass spectrometry analyses, the ALD process temperature was very important for the fabrication of high-quality HfO2 films. The dielectric constant with 275 °C deposition was higher than that at 200–250 °C. Furthermore, the VFB with 200 °C deposition was about 0.1–0.15 V lower than that at 275 °C, due to formation of high residual impurity concentrations, such as carbon, in the HfO2 films. The leakage current densities in the 275 °C case were reduced by about five orders with respect to reference SiO2 films. From these results, it was judged that the ALD process temperature of 275 °C was suitable for the fabrication of ultrathin HfO2 gate dielectrics necessary to improve the leakage current characteristics.
Nanoparticles at the Polydimethylsiloxane Droplet/Water Interface
Authors: Simovic Spomenka , Prestidge Clive A.
Published: September 2005

The adsorption behaviour of nanoparticles at the polydimethylsiloxane droplet/water interface and the influence of particle hydrophobicity, droplet deformability, and the surface electrical properties of both particles and droplets (as controlled by pH and salt concentration) are reported. Adsorption of hydrophilic nanoparticles is weakly influenced by pH but significantly influenced by salt addition, whereas for hydrophobically modified nanoparticles a balance of hydrophobic and electrostatic forces controls adsorption over a wide range of pH and salt concentrations. The relationships between the adsorbed nanoparticle layer structure, droplet stability, and the oil-to-water transport properties have also been elucidated.
Evidence for Why Tri(ethylene oxide) Functionalized Si-C Linked Monolayers on Si(111) Have Inferior Protein Antifouling Properties Relative to the Equivalent Alkanethiol Monolayers Assembled on Gold
Authors: Böcking Till , Gal Michael , Gaus Katharina , Gooding J. Justin
Published: September 2005

High quality methoxy-terminated monolayers containing a tri(ethylene oxide) moiety were formed on Si(111)–H surfaces in thermal hydrosilylation reactions. X-ray photoelectron spectroscopy, contact angle, and X-ray reflectivity measurements suggested that the suboptimal protein anti-fouling properties of these Si–C linked monolayers were due to a reduced lateral packing density of the chains resulting in a disordered layer with insufficient internal and external hydrophilicity.
Solid-Liquid Interactions and Functional Surface Wettability
Authors: Ralston John
Published: September 2005

The interaction between a liquid and a solid surface is the key to understanding wetting phenomena. A very large number of natural and industrial processes rely on the delicate manipulation of this interaction. Controlled wetting is of central importance in microfluidics, mineral flotation, high speed coating, electronic display technologies, oil recovery, lubrication, and plant protection. At the molecular level, one can alter the distribution and charge of surface groups on functional surfaces, vary the number of hydrogen bonds, change molecular configuration, perform chemical grafts, and so forth. External stimuli such as light, electric potential, and heat can lead to subtle control of wettability, which is based strictly on thermodynamics.
Submicron Dispersions of Hexosomes Based on Novel Glycerate Surfactants
Authors: Fong Celesta , Krodkiewska Irena , Wells Darrell , Boyd Ben J. , Booth James , Bhargava Suresh , McDowall Alasdair , Hartley Patrick G.
Published: September 2005

Glycerate-based surfactants are a new class of swelling amphiphiles which swell to a finite degree with water. Among this class of surfactants, oleyl (cis-octadec-9-enyl) glycerate is very similar in structure to a well characterized mesophase-forming lipid, glyceryl monooleate (GMO). Despite the similar structural characteristics, a subtle change in connectivity of the ester bond substantially alters the binary surfactant–water phase behaviour. Whereas the phase behaviour of GMO is diverse and dominated by cubic phases, the phase behaviour of oleyl glycerate and a terpenoid analogue phytanyl (3,7,11,15-tetramethyl-hexadecane) glycerate is much simplified. Both exhibit an inverse hexagonal phase (HII), which is stable to dilution with excess water, and an inverse micellar phase (LII) at ambient temperatures. The inverse hexagonal phases formed by oleyl glycerate and phytanyl glycerate have been characterized using SAXS. Analogous to GMO cubosomes, the inverse hexagonal phase of phytanyl glycerate has been dispersed to form hexagonally facetted particles, termed hexosomes, whose structure has been verified using cryo-TEM.
Determining nitrous oxide emissions from subsurface measurements in grazed pasture: A field trial of alternative technology
Authors: Li Z. , Kelliher F. M.
Published: September 2005

Beneath pasture grazed by farmed animals, the soil’s nitrogen (N), oxygen, and temperature regimes can be unevenly distributed in time and space. It is difficult to capture spatial and temporal variation of N2O using conventional emission measurement technology based on gas samples taken in chambers that briefly cover a small area of the soil’s surface. We report the results from field deployment of alternative, non-intrusive N2O emission measurement technology that uses subsurface measurements incorporating the soil processes controlling the net N2O production and gas diffusion rates. During 100 autumn and winter days after dairy cattle urine was applied (650 kg N/ha) to freely and poorly drained pastoral soils near Hamilton, New Zealand (37.8° S, 175.3° E), N2O emissions were determined. The measured values ranged from 0.024 to 1.55 and 0.048 to 3.33 mg N2O-N/m2.h for the freely and poorly drained soils, respectively. Over the 100 days, it was estimated that 0.4 and 1.3% of the applied N was directly emitted to the atmosphere as N2O from the freely and poorly drained soils, respectively.
Modelling phosphorus exports from rain-fed and irrigated pastures in southern Australia
Authors: Nash D. , Clemow L. , Hannah M. , Barlow K. , Gangaiya P.
Published: September 2005

Pasture-based grazing systems contribute to the excessive nutrients found in some streams in south-eastern Australia. This study investigated phosphorus (P) exported in runoff from a rain-fed dairy pasture (Darnum) and 4 bays of irrigated dairy pasture (MRF). Runoff was monitored for 7 years at Darnum and 2 years at the MRF to identify factors associated with the variation in total P (TP) concentrations between events.
The flow-weighted mean annual P concentrations in runoff varied between 3.3 and 28.2 mg TP/L for Darnum and 6.2 and 31.5 mg TP/L for the MRF. The relationships between TP concentrations in runoff and days between fertiliser application and runoff, days between grazing and runoff, and total storm flow were examined using an additive component model that explained 61% and 70% of the variation in log-transformed TP for Darnum and the MRF, respectively. The interval between application of fertiliser and runoff and the effect of year were highly significant and explained most of the variation in TP. Grazing and fertiliser application were identified as the major factors that may affect TP concentrations that the land manager can control (preventable). The estimates of year effect (i.e. the component of TP not explained by the other variables and over which the land manager had no apparent means of control) ranged from 1.60 mg (s.e. 1.99) to 7.14 mg (s.e. 1.90) TP/L in non-drought years (>45 kL/ha runoff annually). The year effect averaged 5.7 and 6.9 mg TP/L for Darnum and the MRF, respectively. It is shown that an additive component model provides a useful structure for investigating similar, field-scale data.
Transport and deposition of Bacillus subtilis through an intact soil column
Authors: Jiang Guangming , Noonan Mike J. , Buchan Graeme D. , Smith Neil
Published: September 2005

Bacterial transport in unsaturated soils is much less well understood than in saturated conditions, especially for intact soils. This paper aims to investigate the fate and transport of bacteria in intact soils with different water saturations, and particularly the effect of low suction (and hence removal of water flow in the largest macropores). An intact soil column (0.50 m diameter by 0.70 m depth) with a tension infiltrometer was used to investigate the transport and deposition of Bacillus subtilis endospores (i.e. dormant and persistent bacteria) during saturated and unsaturated flows. Soil porosity and pore size distribution were measured. Porosity decreased with depth and macropores were concentrated in the topsoil. Three tensiometers and a temperature sensor were installed along the soil column to monitor matric suction and temperature. Breakthrough curves for bacteria and chemical tracer Br– at 0 and 0.5 kPa suction were obtained during the 3-month leaching experiment. Bacterial breakthrough occurred earlier than the inert chemical tracer, which is consistent with effects of pore size exclusion. Also, saturated flow gave a significantly higher concentration and recovery ratio of leached bacteria, i.e. 51% v. 0.88%. Recovery of Br– in leachate at both suctions reached >85%. The column was destructively sampled for deposited endospores at the completion of leaching. Bacterial deposition was concentrated in the top 0.10 m, then decreased abruptly and was relatively constant with column depth, although showing some irregularity at the bottom of the column.