bluuebunny/crossref_metadata_2025 huggingface dataset:
Rank Prize Lecture Global nutrition challenges for optimal health and well-being
Authors: Uauy Ricardo , Corvalan Camila , Dangour Alan D.
Published: November 2008

Optimal health and well-being are now considered the true measures of human development. Integrated strategies for infant, child and adult nutrition are required that take a life-course perspective to achieve life-long health. The major nutrition challenges faced today include: (a) addressing the pending burden of undernutrition (low birth weight, severe wasting, stunting and Zn, retinol, Fe, iodine and folic acid deficits) affecting those individuals living in conditions of poverty and deprivation; (b) preventing nutrition-related chronic diseases (obesity, diabetes, CVD, some forms of cancer and osteoporosis) that, except in sub-Saharan Africa, are the main causes of death and disability globally. This challenge requires a life-course perspective as effective prevention starts before conception and continues at each stage of life. While death is unavoidable, premature death and disability can be postponed by providing the right amount and quality of food and by maintaining an active life; (c) delaying or avoiding, via appropriate nutrition and physical activity interventions, the functional declines associated with advancing age. To help tackle these challenges, it is proposed that the term ‘malnutrition in all its forms’, which encompasses the full spectrum of nutritional disorders, should be used to engender a broader understanding of global nutrition problems. This term may prove particularly helpful when interacting with policy makers and the public. Finally, a greater effort by the UN agencies and private and public development partners is called for to strengthen local, regional and international capacity to support the much needed change in policy and programme activities focusing on all forms of malnutrition with a unified agenda.
Japanese corporations and popular music
Authors: Atsuko Kimura
Published: November 2008

It has been a long time since Japan was first considered an economic power. Japanese automobile, electronic and computer companies have entered the world market and are now competing fiercely with each other. Their financial power and technologies are focused both domestically and overseas, and their launch into culture through advertising strategies is another facet of that power which has emerged since the 1980s (Un'no 1990).
Death metal tonality and the act of listening
Authors: Berger Harris M.
Published: November 2008

In recent years popular music scholars have paid increasing attention to musical sound. From Robert Walser's landmark work on heavy metal (1993), to Alan Moore's important analysis of rock style periods (1993), to a number of shorter studies (Whiteley 1990; Josephson 1992; Bowman 1995; Ford 1995; Hawkins 1996; Edström 1996), more and more scholars have recognised that all levels of scholarly focus must be pursued if we are to gain purchase on the phenomena of popular music. With no exceptions of which I am aware, all the popular music scholars concerned specifically with musical sound seek to explore the connections between sound and its social contexts. My goal here is to show how attention to musical perception can forward this project and to argue that perception is best understood as a kind of social practice. The act of perception constitutes musical forms and musical meanings in experience. The act of perception is where the rubber of sound meets the road of social life, and by treating perception as a practice we can draw more intimate connections between songs and subjects, sound and society, than would be possible if we were to start from musical structures and then search for linkages to social context. None of this, of course, is to deny the value of studies focused on musical structures, performance events, broad social contexts or large-scale social history, but to argue that the constitution of musical perception by musicians and listeners deserves greater attention and to suggest how this kind of scrutiny might serve the larger aims of popular music studies.
Pop and the Nation-State: towards a theorisation
Authors: Cloonan Martin
Published: November 2008

Recent years have seen two noticeable trends in Popular Music Studies. These have been on the one hand a series of works which have tried to document the ‘local’ music scene and, on the other, accounts of processes of globalisation. While not uninterested in the intermediate Nation-State level, both trends have tended to regard it as an area of increasingly less importance. To state the matter more boldly, both trends have underplayed the continually important role of the Nation-State.
A Saturated Time: Three Festivals in Poland, 2007
Authors: Edmond Murray
Published: November 2008

What different kinds of festival are to be found on the ever-expanding international circuit? What companies are invited or gatecrash the events? What is the role of festivals and festival-going in a global theatrical economy? In this article Murray Edmond describes three festivals which he attended in Poland in the summer of 2007 – the exemplary Malta Festival, held in Poznan; the Warsaw Festival of Street Performance; and the Brave Festival (‘Against Cultural Exile’) in Wroclaw – and through an analysis of specific events and productions suggests ways of distinguishing and assessing their aims, success, and role in what Barthes called the ‘special time’ which festivals have occupied since the Ancient Greeks dedicated such an occasion to Dionysus. Murray Edmond is Associate Professor of Drama at the University of Auckland, New Zealand. His recent publications include Noh Business (Berkeley: Atelos Press, 2005), a study, via essay, diary, and five short plays, of the influence of Noh theatre on the Western avant-garde, and articles in Contemporary Theatre Review (2006), Australasian Drama Studies (April 2007), and Performing Aotearoa: New Zealand Theatre and Drama in an Age of Transition (2007). He works professionally as a dramaturge, notably for Indian Ink Theatre Company, and has also published ten volumes of poetry, of which the most recent is Fool Moon (Auckland: Auckland University Press, 2004).
Chekhov's Poetic and Social Realism on the Italian Stage, 1924–1964
Authors: Sica Anna
Published: November 2008

This article explores the introduction of Chekhov's plays to Italy through émigré circles in the first decades of the twentieth century, and traces how they were appropriated to suit the ideological exigencies of the time during the fascist period. It concludes with observations about Luchino Visconti's celebrated productions of the 1950s, which stressed the idea that Chekhov was first and foremost a political writer, and suggests how this particular view of the dramatist evolved in the early 1960s as the theatre once again reflected social attitudes and values. Anna Sica is a lecturer at the University of Palermo. She has published monographs in Italy on the commedia dell'arte (1997), Arthur Penn (2000), and theatre in New York (2005), as well as articles on Pirandello and contemporary Italian drama in various journals.
The Citizenship Debate and Theatre for Young People in Contemporary Scotland
Authors: Scullion Adrienne
Published: November 2008

In this article Adrienne Scullion reviews the citizenship debate in education policy within contemporary – and specifically post-devolution – Scotland. She identifies something of the impact that this debate has had on theatre-making for children and young people, with a particular focus on projects that are participatory in nature. Her key examples are drawn from TAG Theatre Company's ‘Making the Nation’ project, a major three-year initiative that sought to engage children and young people throughout Scotland in ideas around democracy, politics, and government. Revisiting a classic cultural policy stand-off between instrumental and aesthetic outcomes, she asks whether a policy-sanctioned emphasis on process, transferable skills, and capacity building limits the potential for theatre projects to develop other kinds of theatre skills, such as critical reading and/or spectatorship. With its emphasis on participatory projects rather than plays for children and young people, the article complements her earlier essay, ‘“And So This Is What Happened”: War Stories in New Drama for Children’, in NTQ 84 (November 2005). Adrienne Scullion teaches in the Department of Theatre, Film, and Television Studies at the University of Glasgow.
Pro-Lie groups which are infinite-dimensional Lie groups
Authors: HOFMANN K. H. , NEEB K.-H.
Published: November 2008

A pro-Lie group is a projective limit of a family of finite-dimensional Lie groups. In this paper we show that a pro-Lie group G is a Lie group in the sense that its topology is compatible with a smooth manifold structure for which the group operations are smooth if and only if G is locally contractible. We also characterize the corresponding pro-Lie algebras in various ways. Furthermore, we characterize those pro-Lie groups which are locally exponential, that is, they are Lie groups with a smooth exponential function which maps a zero neighbourhood in the Lie algebra diffeomorphically onto an open identity neighbourhood of the group.
The equivariant cohomology ring of weighted projective space
Authors: BAHRI ANTHONY , FRANZ MATTHIAS , RAY NIGEL
Published: November 2008

We describe the integral equivariant cohomology ring of a weighted projective space in terms of piecewise polynomials, and thence by generators and relations. We deduce that the ring is a perfect invariant, and prove a Chern class formula for weighted projective bundles.
Refractory depression in late life: a review of treatment options
Authors: Baldwin RC
Published: November 2008

There seems reasonable, if depressing, agreement from studies of mixed aged subjects and elderly subjects in psychiatric settings that nonresponse or poor response to a course of an antidepressant occurs in at least one-third of depressed patients. The figure may be higher in elderly patients in general and those with poor physical health. The human cost of chronic depression is highlighted in the Medical Outcomes Study. The level of functional impairment and intereference with quality of life associated with depression was comparable with or worse than that of eight major chronic medical conditions, including diabetes, arthritis and severe coronary artery disease. The final tragedy for unremitting depression may of course be suicide.
Heat transport in a convecting layer heated from within and below
Authors: Moore William B.
Published: November 2008

The heat transport scaling relationships for fluids heated from within and below are established based on numerical calculations of isoviscous Boussinesq convection at infinite Prandtl number. The internal temperatures scale in a way that is similar to the internally heated case but with an offset equal to the average of the two boundary temperatures, reflecting the underlying temperature structure of bottom‐heated convection. The heat fluxes through the boundaries scale as a linear combination of the end‐member modes of heat transport, consistent with the effects of internal heating on the interior temperature. The boundary layer thicknesses, however, depend on H and Ra in a nonintuitive way. As the internal temperature increases with the addition of internal heating, the upper thermal boundary layer thickens despite the increased temperature drop across the layer (the reverse is true for the bottom boundary layer). This is inconsistent with the idea that the boundary layer thickness is controlled by a stability condition on the local Rayleigh number, which would predict that the boundary layer would thin as the temperature drop increases. Deriving boundary layer thicknesses from the scalings for heat flux and boundary layer temperature drop provides an excellent fit to the model results and reveals the importance of plumes arriving from the other boundary layer in establishing the boundary layer thickness. This suggests that, although widely used, boundary layer stability analysis is not an accurate description of the processes controlling boundary layer thickness in systems with two active boundary layers at moderate Ra.
Nitrogen controls plant canopy light‐use efficiency in temperate and boreal ecosystems
Authors: Kergoat Laurent , Lafont Sébastien , Arneth Almut , Le Dantec Valérie , Saugier Bernard
Published: November 2008

Optimum daily light‐use efficiency (LUE) and normalized canopy photosynthesis (GEE*) rate, a proxy for LUE, have been derived from eddy covariance CO2 flux measurements obtained at a range of sites located in the mid to high latitudes. These two variables were analyzed with respect to environmental conditions, plant functional types (PFT) and leaf nitrogen concentration, in an attempt to characterize their variability and their potential drivers. LUE averaged 0.0182 mol/mol with a coefficient of variation of 37% (42% for GEE*). Foliar nitrogen N of the dominant plant species was found to explain 71% of LUE (n = 26) and 62% of GEE* (n = 44) variance, across all PFTs and sites. Mean Annual Temperature, MAT, explained 27% of LUE variance, and the two factors (MAT and N) combined in a simple linear model explain 80% of LUE and 76% GEE* variance. These results showed that plant canopies in the temperate, boreal and arctic zones fit into a general scheme closely related to the one, which had been established for plant leaves worldwide. The N‐MAT‐LUE relationships offer perspectives for LUE‐based models of terrestrial photosynthesis based on remote sensing. On a continental scale, the decrease of LUE from the temperate to the arctic zone found in the data derived from flux measurements is not in line with LUE resulting from inversion of atmospheric CO2.
Low temperature aqueous ferric sulfate solutions on the surface of Mars
Authors: Chevrier Vincent F. , Altheide Travis S.
Published: November 2008

We have studied the low‐temperature properties of ferric sulfate Fe2(SO4)3 solutions as a model for potential liquid brines on the surface of Mars. Geochemical modeling demonstrates that concentrated ferric sulfate brines form through sulphur‐rich acidic evaporation processes in cold oxidizing environments. Experiments and thermodynamic calculations show that the Fe2(SO4)3 eutectic temperature is 205 ± 1 K for 48 ± 2 wt% concentration. As a result of low water activity, these solutions exhibit evaporation rates ranging from 0.42 mm h−1 (29.1 wt%) to 0.03 mm h−1 (58.2 wt%), thus down to 20 times lower than pure water. The combination of extremely low eutectic temperature and evaporation rates allow subsurface liquids to be stable at high latitudes, where the majority of gullies and viscous flow features are located. Therefore, we conclude that episodic releases of highly concentrated ferric sulfate brines are a potential agent for the formation of recent and present‐day gullies on Mars.
How sensitive is tropospheric oxidation to anthropogenic emissions?
Authors: Wild Oliver , Palmer Paul I.
Published: November 2008

We use a global chemistry transport model to explore how changes in anthropogenic emissions alter ozone production and tropospheric oxidizing capacity over decadal (1990–2010) and centennial timescales (1900–2100). We find that the spatial extent of O3 production and loss in the troposphere changes very little despite large projected increases in precursor emissions. While tropospheric OH shows a long‐term decrease of only 20% between 1900 and 2100, there are widespread changes in distribution which alter regional oxidation capacity substantially. We show that the remote marine boundary layer remains an important net sink of O3, as greater production related to increased continental NOx emissions is outweighed by greater O3 destruction. The critical NOx level required to support net O3 production doubles between 1900 and 2100, from 28 to 55 pptv on average, preventing any large‐scale shift in production regime.
Effects of heavy ions on ULF wave resonances near the equatorial region
Authors: Lee D.‐H. , Johnson J. R. , Kim K. , Kim K.‐S.
Published: November 2008

Pc1‐2 ULF waves are strongly associated with the presence of various ions in the magnetosphere. We investigate the role of heavy ion resonances in nonuniform plasmas near the equatorial region. By adopting the invariant imbedding method, the coupled plasma wave equations are solved in an exact manner to calculate the resonant absorption at the ion‐ion hybrid resonance. Our results show that irreversible mode conversion occurs at the resonance, which absorbs the fast wave energy. It is found that waves near the resonances appear with linear polarization, and their amplitude and frequency are sensitive to the properties of the heavy ion plasma composition. We examine how these resonances occur for various H+‐He+ populations in detail by performing an accurate calculation of the mode conversion efficiency. Because the multi‐ion hybrid resonance locations in cold plasmas are determined by simple parameters, such as the fraction of the ion number density of each species and the magnetic field, we suggest that it is possible to monitor heavy ion composition by examining the peak frequencies of linearly polarized wave events in either electric field or magnetic field spectral data.
Single‐particle oxidation state and morphology of atmospheric iron aerosols
Authors: Takahama S. , Gilardoni S. , Russell L. M.
Published: November 2008

Sixty‐three iron‐containing particles from five field campaigns (PELTI, ACE‐Asia, MILAGRO (urban location and aloft on NCAR C‐130), INTEX‐B) were characterized with scanning transmission X‐ray microscopy and near‐edge X‐Ray absorption fine structure L‐edge spectroscopy (NEXAFS‐STXM). Particle sizes ranged from 0.2 to 4.5 μm and were found in many types of morphologies. Iron was found to exist in many different oxidation states with average Fe(II) to Fe(II) + Fe(III) ratios ranging from 0.0 to 0.73. Twenty‐two inclusions and six agglomerations were found. For 29 particles, concurrent (spatially resolved) carbon K‐edge absorption spectra were collected; X‐ray images suggest that in some instances, there are clear phase barriers between iron and carbonaceous regions in agglomerations and irregular particles. Occurrences of Fe(II) fractions and organic functional group abundances among particles appeared primarily in two clusters, one group high in both values and the other low in both, though consistent correlations between the two variables within each particle were not observed. The reduced form of iron on particle surfaces was observed in 16 particles, possibly suggesting atmospheric processing. For this limited set of particles, neither inferred particle source nor surface processing was by itself a strong predictor of overall Fe(II) fraction, indicating that both are important for variables contributing to the observed Fe(II) fraction in the atmosphere. In addition, seven spherical particles from the ACE‐Asia campaign showed an iron shell with an absence of iron toward the core. These particles have carbon spectra characteristics consistent with tarballs described by Posfai et al. (2004), Hand et al. (2005), and Tivanski et al. (2007), which were previously identified as homogeneous carbon spherules. In this work, NEXAFS‐STXM has detected heterogeneities in iron distribution and redox state over individual particles, showing the existence of a variety of types of iron particles in the atmosphere. Such information can be useful in improving models of iron particles, including deposition and fate in seawater.
Optical‐microphysical cirrus model
Authors: Reichardt J. , Reichardt S. , Lin R.‐F. , Hess M. , McGee T. J. , Starr D. O.
Published: November 2008

A model is presented that permits the simulation of the optical properties of cirrus clouds as measured with depolarization Raman lidars. It comprises a one‐dimensional cirrus model with explicit microphysics and an optical module that transforms the microphysical model output to cloud and particle optical properties. The optical model takes into account scattering by randomly oriented or horizontally aligned planar and columnar monocrystals and polycrystals. Key cloud properties such as the fraction of plate‐like particles and the number of basic crystals per polycrystal are parameterized in terms of the ambient temperature, the nucleation temperature, or the mass of the particles. The optical‐microphysical model is used to simulate the lidar measurement of a synoptically forced cirrostratus in a first case study. It turns out that a cirrus cloud consisting of only monocrystals in random orientation is too simple a model scenario to explain the observations. However, good agreement between simulation and observation is reached when the formation of polycrystals or the horizontal alignment of monocrystals is permitted. Moreover, the model results show that plate fraction and morphological complexity are best parameterized in terms of particle mass, or ambient temperature which indicates that the ambient conditions affect cirrus optical properties more than those during particle formation. Furthermore, the modeled profiles of particle shape and size are in excellent agreement with in situ and laboratory studies, i.e., (partly oriented) polycrystalline particles with mainly planar basic crystals in the cloud bottom layer, and monocrystals above, with the fraction of columns increasing and the shape and size of the particles changing from large thin plates and long columns to small, more isometric crystals from cloud center to top. The findings of this case study corroborate the microphysical interpretation of cirrus measurements with lidar as suggested previously.
Empirical two‐point α‐mixing model for calibrating the ECH2O EC‐5 soil moisture sensor in sands
Authors: Sakaki Toshihiro , Limsuwat Anuchit , Smits Kathleen M. , Illangasekare Tissa H.
Published: November 2008

Recently improved ECH2O soil moisture sensors have received significant attention in many field and laboratory applications. Focusing on the EC‐5 sensor, a simple and robust calibration method is proposed. The sensor‐to‐sensor variability in the readings (analog‐to‐digital converter (ADC) counts) among 30 EC‐5 sensors was relatively small but not negligible. A large number of ADC counts were taken under various volumetric water contents (θ) using four test sands. The proposed two‐point α‐mixing model, as well as linear and quadratic models, was fitted to the ADC – θ data. Unlike for conventional TDR measurements, the effect of sensor characteristics is lumped into the empirical parameter α in the two‐point α‐mixing model. The value of α was fitted to be 2.5, yielding a nearly identical calibration curve to the quadratic model. Errors in θ associated with the sensor‐to‐sensor variability for the two‐point α‐mixing model were ±0.005 cm3 cm−3 for dry sand and ±0.028 cm3 cm−3 for saturated sand. In the validation experiments, the highest accuracy in water content estimation was achieved when sensor‐specific ADCdry and ADCsat were used in the two‐point α‐mixing model. Assuming that α = 2.5 is valid for most mineral soils, the two‐point α‐mixing model only requires the measurement of two extreme ADC counts in dry and saturated soils. Sensor‐specific ADCdry and ADCsat counts are readily measured in most cases. Therefore, the two‐point α‐mixing model (with α = 2.5) can be considered as a quick, easy, and robust method for calibrating the ECH2O EC‐5 sensor. Although further investigation is needed, the two‐point α‐mixing model may also be applied to calibrating other sensors.
Cathode effects in cylindrical Hall thrusters
Authors: Granstedt E. M. , Raitses Y. , Fisch N. J.
Published: November 2008

Stable operation of a cylindrical Hall thruster has been achieved using a hot wire cathode, which functions as a controllable electron emission source. It is shown that as the electron emission from the cathode increases with wire heating, the discharge current increases, the plasma plume angle reduces, and the ion energy distribution function shifts toward higher energies. The observed effect of cathode electron emission on thruster parameters extends and clarifies performance improvements previously obtained for the overrun discharge current regime of the same type of thruster, but using a hollow cathode neutralizer. Once thruster discharge current saturates with wire heating, further filament heating does not affect other discharge parameters. The saturated values of thruster discharge parameters can be further enhanced by optimal placement of the cathode wire with respect to the magnetic field.
Magnetic levitation in two-dimensional geometry with translational invariance
Authors: Lorin C. , Mailfert A.
Published: November 2008

The development of activities in space and of the corresponding technologies requires research on the behavior of both matter and biological organisms under weightless conditions. Various methods have been invented in order to simulate weightlessness, for example, drop towers, sounding rockets, or parabolic flights. Magnetic field ground-based devices have also been developed. This paper introduces an optimization method of the magnetic field so as to obtain magnetic levitation in a two-dimensional cylindrical geometry.
Heterogeneous dynamics of ionic liquids from molecular dynamics simulations
Authors: Habasaki J. , Ngai K. L.
Published: November 2008

Molecular dynamics simulations have been performed to study the complex and heterogeneous dynamics of ions in ionic liquids. The dynamics of cations and anions in 1-ethyl-3-methyl imidazolium nitrate (EMIM-NO3) are characterized by van Hove functions and the corresponding intermediate scattering functions Fs(k,t) and elucidated by the trajectories augmented by the use of singular spectrum analysis (SSA). Several time regions are found in the mean squared displacement of the ions. Change in the slope in a plot of the diffusion coefficient against temperature is found at around 410K in the simulation. Heterogeneous dynamics with the presence of both localized ions and fast ions capable of successive jumps were observed at long time scales in the self-part of the van Hove functions and in the trajectories. Non-Gaussian dynamics are evidenced by the self-part of the van Hove functions and wave number dependence of Fs(k,t) and characterized as Lévy flights. Successive motion of some ions can continue even after several nanoseconds at 370K, which is longer than the onset time of diffusive motion, tdif. Structure of the long time dynamics of fast ions is clarified by the phase space plot of the successive motion using the denoised data by SSA. The continual dynamics are shown to have a long term memory, and therefore local structure is not enough to explain the heterogeneity. The motion connecting localized regions at about 370K is jumplike, but there is no typical one due to local structural changes during jump motion. With the local motion, mutual diffusion between cation and anion occurs. On decreasing temperature, mutual diffusion is suppressed, which results in slowing down of the dynamics. This “mixing effect of cation and anion” is compared with the “mixed alkali effect” found in the ionics in the ionically conducting glasses, where the interception of paths by different alkali metal ions causes the large reduction in the dynamics [J. Habasaki and K. L. Ngai, Phys. Chem. Chem. Phys. 9, 4673 (2007), and references herein]. Although a similar mechanism of the slowing down is observed, strong coupling of the motion of cation and anion prevents complete interception unless deeply supercooled, and this explains the wide temperature region of the existence of the liquid and supercooled liquid states in the ionic liquid.
Analysis of polyatomic molecules using high resolution coherent two-dimensional spectroscopy: Application to nitrogen dioxide
Authors: Chen Peter C. , Mitchell Kamilah
Published: November 2008

The peak-sorting capabilities of high resolution coherent two-dimensional (2D) spectroscopy provide a new way of dealing with severe rotational congestion. This paper describes the application of this technique to the polyatomic molecule, NO2. NO2 is a primary component of photochemical smog and has a notoriously complex and congested spectrum that extends from the infrared to the ultraviolet regions. This spectrum is infamous for having an unusually high density of peaks and very few regular patterns. However, the coherent 2D spectrum of NO2 shows a network consisting of numerous X-shaped patterns that mark the locations of vibronic origins. This paper describes how peak sorting leads to the formation of such patterns and how peak coupling can be used to conduct a rotational analysis of congested areas in the visible spectrum of NO2.
Relative periodic orbits in transitional pipe flow
Authors: Duguet Yohann , Pringle Chris C. T. , Kerswell Rich R.
Published: November 2008

A dynamical system description of the transition process in shear flows with no linear instability starts with knowledge of exact coherent solutions, among them traveling waves (TWs) and relative periodic orbits (RPOs). We describe a numerical method to find such solutions in pipe flow and apply it in the vicinity of a Hopf bifurcation from a TW which looks to be especially relevant for transition. The dominant structural feature of the RPO solution is the presence of weakly modulated streaks. This RPO, like the TW from which it bifurcates, sits on the laminar-turbulent boundary separating initial conditions which lead to turbulence from those which immediately relaminarize.
Optimal alignment control of a nonpolar molecule through nonresonant multiphoton transitions
Authors: Nakagami Kazuyuki , Mizumoto Yoshihiko , Ohtsuki Yukiyoshi
Published: November 2008

Alignment control of an ensemble of nonpolar molecules is numerically studied by means of optimal control simulation. A nitrogen molecule that is modeled by a quantum rigid rotor is adopted. Controlled rotational wave packets are created through nonresonant optical transitions induced by polarizability coupling. Optimal pulses are designed to achieve the alignment control at a specified time in the absence/presence of external static fields in zero- and finite-temperature cases, as well as to maintain an aligned state. When maintaining an aligned state over a specified time interval is chosen as a target, the control mechanism is primarily attributed to a dynamical one. Multiple optimal solutions that lead to virtually the same control achievement are found, which are consistent with the topology of the quantum control landscape.
Coarse grained open system quantum dynamics
Authors: Thanopulos Ioannis , Brumer Paul , Shapiro Moshe
Published: November 2008

We show that the quantum dynamics of a system comprised of a subspace Q coupled to a larger subspace P can be recast as a reduced set of “coarse grained” ordinary differential equations with constant coefficients. These equations can be solved by a single diagonalization of a general complex matrix. The method makes no assumptions about the strength of the couplings between the Q and the P subspaces, nor is there any limitation on the initial population in P. The utility of the method is demonstrated via computations in three following areas: molecular compounds, photonic materials, and condensed phases.
Initiation of underwater granular avalanches: Influence of the initial volume fraction
Authors: Pailha M. , Nicolas M. , Pouliquen O.
Published: November 2008

We experimentally investigate how a layer of granular material fully immersed in a liquid starts to flow when suddenly inclined from a horizontal position. The flow is shown to strongly depend on the initial volume fraction, its initiation being dramatically delayed by a slight initial compaction. A model, which takes into account the dilatant behavior of the granular material and the coupling with the interstitial fluid, captures the main experimental features.
Spatio-temporal Talbot phenomenon using metamaterial composite right/left-handed leaky-wave antennas
Authors: Gómez-Díaz J. S. , Alvarez-Melcon A. , Gupta S. , Caloz C.
Published: November 2008

A spatial-temporal Talbot phenomenon, based on metamaterial composite right/left-handed (CRLH) leaky-wave antennas (LWAs), is presented. This phenomenon, reported in the microwave domain, is based on the combination of the conventional spatial monochromatic Talbot effect and the transient (polychromatic) character of the pulse radiation phenomenon in the LWA structure. When the elements of a periodic CRLH LWA array are fed simultaneously by an input pulse, the spatial beams corresponding to different temporal frequencies constructively interfere in space so as to form a self-imaged pattern constituted by narrow Talbot zones. This Talbot effect is spatial-temporal since the Talbot zones are localized both in space and time. The phenomenon is analyzed theoretically and validated numerically for the case of narrow-band pulses.
On PbTiO3-(111)-Pt interfacial layers and their x-ray photoelectron spectroscopy signature
Authors: Habouti S. , Solterbeck C-H. , Es-Souni M. , Zaporojtchenko V.
Published: November 2008

In this work emphasis is placed on the investigation of interfacial layers between sol-gel processed PbTiO3 (PTO) thin films and (111)Pt terminated silicon substrates. The methods used are x-ray diffraction, x-ray photoelectron spectroscopy (XPS) combined with depth profiling, and atomic force microscopy (AFM). In order to avoid artifacts related to ion bombardment, e.g., reduction of Pb ions and preferential sputtering, gentle argon ion bombardment conditions were first derived. AFM investigations of native and ion bombarded films at different stages of depth profiling show that the films are homogenously sputtered, whereby the film roughness remains practically unchanged in the course of sputtering. An annealing treatment at 550 °C under reducing atmosphere was used to provoke the formation of an interfacial intermetallic (111)PtxPb phase, which is shown to coexist with an amorphous oxide film. This could allow us to establish the XPS signature of the intermetallic phase. A negative shift of the Pt (4f) binding energy and a large full width at half maximum of the Pb (4f) peak are the attributes of this signature. PTO-film annealing in air at temperatures between 350 and 600 °C leads to the formation of the perovskite phase, starting at 500 °C, directly from the amorphous phase. Based on its derived XPS signature it is shown that the intermetallic phase still exists at the interface with variable thickness depending on the annealing temperature. The pronounced (111) texture of the PTO-crystallized films is thought to be the direct consequence of this intermetallic template layer. It is also shown that the outermost surface of the PTO film is enriched with PbO as a result of segregation phenomena.
dc leakage mechanism in artificial biferroic superlattices
Authors: Chaudhuri Ayan Roy , Krupanidhi S. B.
Published: November 2008

The dc leakage behavior of 0.7Pb(Mg1/3Nb2/3)O3−0.3PbTiO3/La0.6Sr0.4MnO3 asymmetric superlattices has been studied over a wide range of temperatures between 30 and 200 °C. Leakage current characteristics analyzed in the light of different models indicated dominant Poole–Frenkel emission in the lower electric field region. Activation energy calculated from the Poole–Frenkel model was in the range of 0.19–0.34 eV for different superlattice periodicities. For the superlattices with lower periodicities (6 nm) dc leakage current in the low electric field region was dominated collectively by both Ohmic and Poole–Frenkel conduction mechanisms. At higher applied electric fields space charge limited conduction was found to be the dominant mechanism for all the superlattices. Realization of leakage mechanism over different temperatures and voltages can help in strategic interface engineering of these superlattices for device applications.
Microstructures and the corresponding magnetic properties of half-doped Nd0.5Sr0.5MnO3 films
Authors: Prokhorov V. G. , Hyun Y. H. , Park J. S. , Kim J. B. , Kim G. H. , Lee Y. S. , Lee Y. P. , Svetchnikov V. L.
Published: November 2008

The microstructural and magnetic properties of amorphous, nanoclustered, and self-organized bilayer Nd0.5Sr0.5MnO3 films, prepared by rf magnetron sputtering, are investigated. The amorphous film was found to be a typical paramagnet with free motion of the individual Mn spins, and the magnetic properties are well described on the basis of the Curie–Weiss approximation. The nanoclustered film manifests magnetic properties mimicking those of superparamagnetic particles following nonclassical magnetic dynamics. The self-organized bilayer film demonstrates a negative exchange bias typical of a ferromagnet/antiferromagnet hybrid system, in spite of the fact that both layers have a ferromagnetic origin. The magnetic properties of the films are discussed in detail on the basis of modern theoretical models.
The role of implantation-induced point defects for the redistribution of oxygen in silicon at high-temperature processing
Authors: Kögler R. , Ou X. , Skorupa W. , Möller W.
Published: November 2008

The excess of implantation-induced point defects controls the oxygen redistribution in silicon during a high-temperature treatment, such as in separation-by-implanted-oxygen, and defines the energy-dose window for the formation of a perfect homogeneous and planar buried oxide layer. Quantitative relations are given between the distribution of the initially generated excess defects and the finally formed oxide layer. Implantation-induced defects also explain the depth positions of different oxide precipitate layers and of silicon islands inside the oxide layer. Other defects as, e.g., dislocations, which form during thermal treatment, may relocate the energy-dose window toward a lower oxygen dose.
Potential for application of an acoustic camera in particle tracking velocimetry
Authors: Wu Fu-Chun , Shao Yun-Chuan , Wang Chi-Kuei , Liou Jim
Published: November 2008

We explored the potential and limitations for applying an acoustic camera as the imaging instrument of particle tracking velocimetry. The strength of the acoustic camera is its usability in low-visibility environments where conventional optical cameras are ineffective, while its applicability is limited by lower temporal and spatial resolutions. We conducted a series of experiments in which acoustic and optical cameras were used to simultaneously image the rotational motion of tracer particles, allowing for a comparison of the acoustic- and optical-based velocities. The results reveal that the greater fluctuations associated with the acoustic-based velocities are primarily attributed to the lower temporal resolution. The positive and negative biases induced by the lower spatial resolution are balanced, with the positive ones greater in magnitude but the negative ones greater in quantity. These biases reduce with the increase in the mean particle velocity and approach minimum as the mean velocity exceeds the threshold value that can be sensed by the acoustic camera.
Comparison of resonant-phonon-assisted terahertz quantum-cascade lasers with one-well injector and three-well module
Authors: Li H. , Cao J. C. , Tan Z. Y. , Feng S. L.
Published: November 2008

The authors compare resonant-phonon-assisted terahertz quantum-cascade lasers with different active region designs, i.e., one-well injector and three-well module, using an ensemble Monte Carlo method. Carrier transport under injection anticrossing, parasitic anticrossing, and collection anticrossing couplings are investigated for both structures. The results show that the main parasitic current channel is the resonance of the injector 1′ with the lower lasing level 3 and one-well injector design benefits a high injection selectivity because of a better Δ1′4/Δ1′3 ratio. Due to the diagonal radiative transition, the one-well injector design sacrifices the oscillator strength and modal gain to reduce the parasitic coupling. Temperature evaluation shows that longitudinal-optical phonon emission is the dominant scattering mechanism contributing to lasing and the calculated modal gain in the one-well design shows a slower decreasing rate with temperature.
Mechanisms of the ultrasonic modulation of fluorescence in turbid media
Authors: Yuan Baohong , Gamelin John , Zhu Quing
Published: November 2008

To understand the modulation mechanisms of fluorescence emission induced by ultrasonic waves in turbid media, a mathematical model is proposed and compared with the recent experimental observations of Kobayashi et al. [Appl. Phys. Lett. 89, 181102 (2006)]. Modulation of fluorophore concentration is considered as the source of the oscillation of fluorescence signals when fluorophore concentration is low enough so that quenching effects can be ignored. By solving the rate equation and photon diffusion equation, quantitative solutions are given to quantify the modulation strength. Our calculations predict that the modulation depth (the ratio of the modulated signal strength to the unmodulated signal strength) can reach 10−4 when ultrasonic pressure with the order of magnitude of megapascals is applied in the ultrasound focal zone. Our model explains the relationship between the modulation strength and the average fluorophore concentration and also predicts a method to measure or image fluorescence lifetime in the turbid medium. When fluorophore concentration is high enough so that fluorescence quenching occurs, the fluorescence modulation is attributed to the modulation of quenching efficiency. Quenching caused by fluorescence resonance energy transfer can lead to a nonlinear relationship between the modulation fluorescence strength and the applied ultrasound strength.
Temperature dependence of voltage-controlled negative resistance and electroluminescence in Al–Al2O3–Au diodes
Authors: Hickmott T. W.
Published: November 2008

Voltage-controlled negative resistance (VCNR) and unipolar resistive switching that can be used for memory applications can develop in the current-voltage (I-V) curves of metal-insulator-metal diodes. Electroluminescence is intimately connected with the occurrence of VCNR in I-V curves. The temperature dependence of VCNR and electroluminescence of Al–Al2O3–Au diodes with anodic Al2O3 thicknesses between 12 and 54 nm has been studied between 300 and 180 K. There is a threshold voltage, Vth, for the occurrence of electroluminescence. Vth is between 1.5 and 2.0 V at 300 K and is independent of Al2O3 thickness. As temperature is lowered, the maximum current of the I-V curve that exhibits VCNR, Imx, decreases. The voltage for maximum current, Vmx, increases as does Vth. Around 200 K, currents become small and erratic; VCNR and electroluminescence disappear but reappear if the diode temperature is raised above ∼200 K. Detailed measurements of the temperature dependence of Imx, Vmx, and Vth are presented for Al–Al2O3–Au diodes with different anodic Al2O3 thicknesses. The relative electroluminescent intensity is largest in the thinnest samples. A model is proposed for conduction in a filamentary region of an Al–Al2O3–Au diode. Electrons injected into an impurity band in Al2O3 recombine with defect centers in Al2O3 to produce electroluminescence. Positively charged defect centers in Al2O3 cause the formation of an Ohmic contact and a high-field region at the Al–Al2O3 interface. The Ohmic contact, in turn, determines the I-V curves of a conducting channel. Recombination of electrons with defect centers that produce the Ohmic contact changes the Ohmic contact and causes the current decrease in the negative resistance region of the I-V curves.
Accuracy analysis for the determination of electronic transport properties of Si wafers using modulated free carrier absorption
Authors: Zhang Xiren , Li Bincheng , Liu Xianming
Published: November 2008

Computer simulations are carried out to investigate the sensitivity of simultaneous determination of three electronic transport properties (carrier lifetime, carrier diffusivity, and front surface recombination velocity) of silicon wafers by modulated free carrier absorption (MFCA) via a multiparameter fitting procedure. The relative accuracy of the transport parameter determination by laterally resolved MFCA (LR-MFCA), in which the amplitude and phase are measured as functions of the pump-probe-beam separation at several modulation frequencies covering an appropriate range, and by conventional frequency-scan MFCA (FS-MFCA), in which only the modulation frequency dependences of the amplitude and phase are recorded, is theoretically analyzed and experimentally estimated by calculating the dependence of the mean square variance on individual transport parameter via a multiparameter estimation process. Simulated and experimental results show that the determination of the transport properties of silicon wafers by LR-MFCA are more accurate, compared with that by FS-MFCA. Comparative experiments are performed with a silicon wafer and the estimated uncertainties of the carrier diffusivity; lifetime and front surface recombination velocity are approximately ±3.7%, ±25%, and ±35% for LR-MFCA and ±7.5%, ±31%, and ±24% for FS-MFCA, respectively.
Noninertial lateral migration of vesicles in bounded Poiseuille flow
Authors: Coupier Gwennou , Kaoui Badr , Podgorski Thomas , Misbah Chaouqi
Published: November 2008

Cross-streamline noninertial migration of a vesicle in a bounded Poiseuille flow is investigated experimentally and numerically. The combined effects of the walls and of the curvature of the velocity profile induce a movement toward the center of the channel. A migration law (as a function of relevant structural and flow parameters) is proposed that is consistent with experimental and numerical results. This similarity law markedly differs from its analog in unbounded geometry. The dependency on the reduced volume ν and viscosity ratio λ is also discussed. In particular, the migration velocity becomes nonmonotonous as a function of ν beyond a certain λ.
Complete periodic synchronization in coupled systems
Authors: Zou Wei , Zhan Meng
Published: November 2008

Recently, complete chaotic synchronization in coupled systems has been well studied. In this paper, we study complete synchronization in coupled periodic oscillators with diffusive and gradient couplings. Eight typical types of critical curve for the transverse Lyapunov exponent of standard mode, which give rise to different synchronization-desynchronization patterns, are classified. All possible desynchronous behaviors including steady state, periodic state, quasiperiodic state, low-dimensional chaotic state, and two types of high-dimensional chaotic state are identified, and two classical synchronization-desynchronizaiton bifurcations—the shortest wavelength bifurcation and Hopf bifurcation from synchronous periodic state—are classified.
Raman characterization of Ge distribution in individual Si1−xGex alloy nanowires
Authors: Nishimura Chiharu , Imamura Go , Fujii Minoru , Kawashima Takahiro , Saitoh Tohru , Hayashi Shinji
Published: November 2008

The distribution of Ge composition in an individual Si1−xGex alloy nanowire (SiGeNW) grown by the vapor liquid solid (VLS) process was studied by micro-Raman spectroscopy by changing the measurement position from the catalyst side to the substrate side. The Si–Si mode in Raman spectra were found to split into two peaks and the intensity ratio as well as the wavenumbers of the two peaks depended on the measurement position. The Raman data revealed that SiGeNWs have a core-shell structure with a low-Ge composition core grown by the VLS process covered with a high-Ge composition shell grown by the conformal deposition.
Giant reversible magnetocaloric effect in cobalt hydroxide nanoparticles
Authors: Liu X. H. , Liu W. , Hu W. J. , Guo S. , Lv X. K. , Cui W. B. , Zhao X. G. , Zhang Z. D.
Published: November 2008

The magnetocaloric effect associated with magnetic phase transitions in β-Co(OH)2 nanoparticles has been investigated. A sign change in the magnetocaloric effect is induced by a magnetic field, which is related to a field-induced transition from the antiferromagnetic to the ferromagnetic state below the Néel temperature. The large reversible magnetic-entropy change −ΔSm (20.9 J/kg K at 15 K for a field change of 7 T) indicates that β-Co(OH)2 is a potential candidate for application in magnetic refrigeration in the low-temperature range.