bluuebunny/crossref_metadata_2025 huggingface dataset:
Turning dilemmas into opportunities: a UNU/SCN capacity development network in public nutrition in Central and Eastern Europe
Authors: Pavlovic Mirjana , Pepping Fré , Demes Michal , Biro Lajos , Szabolcs Peter , Dimitrovska Zlatka , Duleva Vesselka , Parvan Camelia , Hadziomeragic Aida Filipovic , Glibetic Maria , Oshaug Arne
Published: February 2009

Capacity development in nutrition is a process whereby individuals, groups, institutions, organizations and societies enhance their abilities to identify and meet challenges in a sustainable manner. To address these issues, in 2001 the UN System Standing Committee on Nutrition (SCN) established a Working Group on Capacity Development under the joint coordination of the United Nations University (UNU) and the International Union of Nutritional Sciences. Several regional professional networks have developed under this working group, the latest for the Central and Eastern Europe (CEE) countries. Ten CEE countries formed a network in 2006 and identified major nutritional challenges in the region, which included: irregular meal patterns; low consumption of fruits/vegetables, milk products and fish; low intake of some micronutrients; and high intakes of fat, sugar and salt. Public policies in nutrition were either weak or absent. Some countries had recently developed nutrition plans. Higher education in nutrition was seen as very important for public nutrition work by professionals in the region, who considered it a prerequisite for reversing the negative trend of the nutrition transition. The network will continue to work on issues that are still not covered adequately. Its activities to date and prospects for the future are assessed against ten principles for good capacity development suggested by the United Nations Development Programme.
Rethinking political structures: from ‘ordering principles’ to ‘vertical differentiation’ – and beyond
Authors: Donnelly Jack
Published: February 2009

‘Structure’ in the discipline of International Relations, for all the criticism of Kenneth Waltz’ work, still typically means the Waltzian triad of ordering principles, functional differentiation, and distribution of capabilities. I argue, however, that this triad not only does not in Waltz’ particular presentation but cannot provide an adequate account of political structures. In its place I sketch a five-part framework of the elements of political structures. Three types of structural differentiation are identified: vertical differentiation, which establishes hierarchical ranking; horizontal differentiation, which establishes non-hierarchical segmentation; and unit differentiation, which assigns certain types of actors a privileged status. Two dimensions of structural elaboration are also identified: norms and institutions and technology and geography. This framework highlights the central place of ranking in international political structures, developing a tripartite account of ‘ordering principles’ that identifies autarchic, single-hierarchic, and heterarchic systems. It also draws attention to the diversity of international orders and opens structural analysis to the concerns and contributions of constructivism.
Binding of Event Files in a (go/no-go) Simon Task With an Accessory Peripheral Signal
Authors: Maetens Kathleen , Henderickx David , Soetens Eric
Published: February 2009

To understand the relation between the Simon effect and the time course of relevant and irrelevant code activations, we presented the response signal before or simultaneously with a go/no-go signal in an accessory Simon task. A peripheral accessory signal could appear before, simultaneously with or after the go/no-go signal. We observed a Simon effect when the accessory signal was presented just before or simultaneously with the go signal, irrespective of the delay between response and go/no-go signal. The Simon effect reversed when the accessory signal was presented 150 ms after the go signal when response information was presented first and the participants had to make a go/no-go decision afterwards or when they had to select a response when the go signal appeared. The reversal did not occur when both decisions were required at the same time. Our data suggest that the integration and release of event files are involved in the occurrence of the reversal. Response activation induced by the accessory stimulus facilitates/interferes with the response when it is presented before the event file is integrated. When the accessory stimulus is presented after integration, the automatically activated response is inhibited, causing a delay in the corresponding reaction times.
An Inverse Belief–Bias Effect
Authors: Markovits Henry , Saelen Cécile , Forgues Hugues Lortie
Published: February 2009

Two studies examined the hypothesis that accepting false premises as true in order to make the modus ponens (MP) inference requires inhibition of contradictory knowledge. Study 1 presented both MP and affirmation of the consequent (AC) inferences using either false, but plausible premises or completely unbelievable premises, with standard logical constructions using either an evaluation or a production paradigm. The rate of acceptance of the MP inferences was significantly greater with unbelievable premises than with plausible premises, in both evaluation and production, while no such effect was observed with the AC inferences. Study 2 used a computer-generated presentation allowing for measures of response times. Participants who tended to accept the MP inference with unbelievable premises took longer to do so with plausible premises than with unbelievable premises. Participants who tended to reject the MP inference showed an opposite pattern. In both studies, the observed effects were not shown for the AC inferences. The overall pattern of results was consistent with the hypothesis that inhibition is a key component of logical reasoning with false premises.
The Prioritization of Feature Singletons in the Change Detection Paradigm
Authors: Cole Geoff G. , Kuhn Gustav , Heywood Charles A. , Kentridge Robert W.
Published: February 2009

Six experiments are reported investigating whether a discontinuity in colour can accrue attentional priority. In addition to a standard visual search paradigm, we examined the degree to which colour singletons and nonsingletons are susceptible to change blindness. Results showed that changes occurring at colour singletons were relatively more resistant to change blindness. Although suggestive of bottom-up marshalling of attention, no prioritization of the singleton occurred when the most stringent test of stimulus-driven attentional attraction was employed, that is, when attending to the singleton was detrimental to the task. We conclude that a discontinuity in colour will attract attention unless an attentional set is contrary to singletons.
Amplitude modeling of the seismic reflectors in the crust‐mantle transition layer beneath the volcanic front along the northern Izu‐Bonin island arc
Authors: Sato Takeshi , Kodaira Shuichi , Takahashi Narumi , Tatsumi Yoshiyuki , Kaneda Yoshiyuki
Published: February 2009

The Izu‐Bonin island arc is a typical oceanic island arc formed by subduction of the Pacific plate beneath the Philippine Sea plate. Although some crustal structures of this island arc have been identified, detailed information about the region between the deeper crust and uppermost mantle, especially the crust‐mantle transition layer, has been inadequate to elucidate a crustal growth model. Comparison of the observed and synthetic waveforms of wide‐angle seismic data yielded velocity contrast values of the top and bottom of this transition layer beneath the volcanic front along the northern Izu‐Bonin island arc. Using those data, we clarify the nature of the crust‐mantle transition layer. The top of the crust‐mantle transition layer has a velocity contrast value of about 0.4 km/s in the southern area, extending from Kurose hall to Tori‐shima along the northern Izu‐Bonin island arc, except for the northern area, extending from Nii‐jima to Kurose hall (0.25 km/s). The velocity contrast value at the bottom of this transition layer is large (>0.4 km/s) between Nii‐jima and Kurose hall and small (0.2 km/s) from Kurose hall southward. These results and the average P wave velocity in the crust‐mantle transition layer indicate that this transition layer beneath the volcanic front along the northern Izu‐Bonin island arc is a mixture of mafic residues and olivine cumulates formed during crustal growth. Furthermore, the variation of the velocity contrast at the top and bottom of this transition layer and the average P wave velocity in this layer along this arc imply that this layer in the southern area, extending from Kurose hall southward, has a larger ratio of mantle materials (olivine cumulates) to mafic residues than that in the northern area, extending from Nii‐jima to Kurose hall. The Moho along the volcanic front in the oceanic island arc probably has a complex signature, as suggested by the crust‐mantle transition layer comprising a mixture of mafic residues and olivine cumulates.
Geothermal heat flux and its influence on the oceanic abyssal circulation and radiocarbon distribution
Authors: Hofmann M. , Morales Maqueda M. A.
Published: February 2009

Geothermal heating of abyssal waters is rarely regarded as a significant driver of the large‐scale oceanic circulation. Numerical experiments with the Ocean General Circulation Model POTSMOM‐1.0 suggest, however, that the impact of geothermal heat flux on deep ocean circulation is not negligible. Geothermal heating contributes to an overall warming of bottom waters by about 0.4°C, decreasing the stability of the water column and enhancing the formation rates of North Atlantic Deep Water and Antarctic Bottom Water by 1.5 Sv (10%) and 3 Sv (33%), respectively. Increased influx of Antarctic Bottom Water leads to a radiocarbon enrichment of Pacific Ocean waters, increasing Δ14C values in the deep North Pacific from −269‰ when geothermal heating is ignored in the model, to −242‰ when geothermal heating is included. A stronger and deeper Atlantic meridional overturning cell causes warming of the North Atlantic deep western boundary current by up to 1.5°C.
Observed low‐salinity plume off Gulf of Khambhat, India, during post‐monsoon period
Authors: Rao A. D. , Joshi Madhu , Ravichandran M.
Published: February 2009

Freshwater outflow from river systems, joining the northeastern Arabian Sea suggests that the discharge is maximum during summer monsoon and least during other seasons. However, analysis of climatological monthly salinity and ARGO data indicate, low‐saline plumes off Gulf of Khambhat during post‐monsoon, despite the fact that there is no river discharge during this period. It is puzzling to understand the existence of relatively low‐saline waters in the region that warrants further investigation. Simulations from three‐dimensional Princeton Ocean Model (POM) suggest that the opposing winds and the associated onshore coastal currents during July seem to trap the freshwater in the gulf region. As the monsoon withdraws by September, the currents change their direction that would help in releasing the low‐saline waters to open ocean. Winter cooling of the freshwater also enhances the prospects of temperature inversions.
Monitoring open‐ocean deep convection from space
Authors: Herrmann Marine , Bouffard Jérome , Béranger Karine
Published: February 2009

Deep convection (DC) is a key‐process of the oceanic circulation, costly to monitor in situ and under the influence of climate change. Our study is a first step toward monitoring DC from space: we investigate the feasibility of observing its variability using improved satellite altimetry. An oceanic simulation of the Mediterranean circulation was performed for the 1999–2007 period. DC interannual variability is realistically modelled, and the sea surface elevation (SSE) is in agreement with altimetry data. Numerical results show a strong correlation between the annual DC characteristics and the winter SSE. From that, we propose a method to monitor DC interannual variability and long term evolution using altimetry data. Our method, applied to the longest available altimetry series, represents correctly the interannual variability of DC in the Northwestern Mediterranean between 1994 and 2007.
Regional dust model performance during SAMUM 2006
Authors: Haustein K. , Pérez C. , Baldasano J. M. , Müller D. , Tesche M. , Schladitz A. , Esselborn M. , Weinzierl B. , Kandler K. , von Hoyningen‐Huene W.
Published: February 2009

Traditionally there has been a lack of intensive measurements directly over dust sources for validating the accuracy of dust models. Utilizing the valuable and unprecedented SAMUM 2006 field campaign dust dataset in North Africa, we assess the performance and discuss the limitations of a state‐of‐the‐art dust regional model to reproduce the complex dust patterns encountered during the campaign. The DREAM model operational forecast version during SAMUM 2006 (OPER) and an updated model version (RESH) are run and compared. RESH reproduces the general Saharan dust pattern, whereas OPER shows limitations to quantitatively reproduce dust optical properties over sources and after long range transport simultaneously. Dust transport in RESH with enhanced number size bin distribution is proven to be more efficient and adequate. The modeled vertical extinction coefficient captures fairly well lidar observations. While particle number size distribution is consistently reproduced at surface level, we find significant underestimation in the middle troposphere for large particles. Occasionally, synoptic scale meteorology remains unsatisfactorily captured leading to errors in the location and intensity of dust emission and subsequent transport.
Large scale modulations of spectral aerosol optical depths by atmospheric planetary waves
Authors: Beegum S. Naseema , Krishna Moorthy K. , Babu S. Suresh , Reddy R. Ramakrishna , Gopal K. Rama
Published: February 2009

Analysis of 6 years of spectral aerosol optical depths (AOD), obtained during boreal winter at the tropical semi‐arid location Anantapur, India, revealed significant modulations (to the seasonal mean AOD) by planetary scale atmospheric waves. Most significant contributions came from 30 to 50 day, and quasi‐16 day periodicities; each contributing ∼10% to 24%, and jointly up to 45% to the seasonal mean AOD; the contribution varying linearly with zonal wind speed. Analysis of the upper air wind fields revealed these to be associated with Madden Julian Oscillations and quasi ‐16 day planetary waves. The spectral dependence of AOD also responded to these waves, becoming flatter with the strengthening of the MJO and steeper with the quasi‐16 oscillations. The possible implications of these to the long‐range transport of different aerosol types to the measurement region are discussed. The findings signify the role of natural atmospheric motions in producing significant changes in spectral AOD, which will have strong implications to regional climate.
Detecting nanoparticles at radio frequencies: Jovian dust stream impacts on Cassini/RPWS
Authors: Meyer‐Vernet N. , Lecacheux A. , Kaiser M. L. , Gurnett D. A.
Published: February 2009

We analyse wave observations by the Cassini/RPWS instrument performed during the Jovian fly‐by, when the on‐board dust analyser recorded dust streams which were interpreted as nanoparticles moving at about the solar wind speed. The observed wave pulses are produced by ionisation of dust grains impacting the spacecraft. Nanoparticles are detected because they move fast and the voltage produced by impact ionisation increases very fast with speed, so that they produce wave pulses as high as do much larger grains of smaller speeds. The observed wave level and spectral shape are compatible with those expected for the streams deduced from the dust analyser observations, and the impact rates observed on both instruments appear to vary similarly. The present result is the first wave detection simultaneous with a conventional detection by a dust analyser attributed to nanoparticles.
Observations of electric fields associated with internal gravity waves
Authors: Varney Roger H. , Kelley Michael C. , Kudeki Erhan
Published: February 2009

At the Jicamarca Radio Observatory, the vertical drift component yields a very accurate measure of the eastward electric field. Occasionally, this drift component displays a downward phase progression, evidence for a relationship to a gravity wave. We examined the Jicamarca database for events of this type and made an attempt to determine the properties of the associated waves. The only measurables we have are the amplitudes, the frequency in the Earth‐fixed frame, and the vertical wavelength. In order to avoid shorting by the current along magnetic field lines, we argue that the propagation must be close to pure zonal. We then use measurements or models of the zonal plasma drift and argue that the zonal wind should be in the same direction and about 15% higher. Using this estimate, we then determine the frequency in the wind frame by solving the dispersion relation for gravity waves and the Doppler‐shift equation simultaneously. Typical values for the horizontal wavelength, vertical wavelength, and period in the wind frame are 600 km, 350 km, and 25 min, respectively. The typical gravity wave‐induced vertical drift perpendicular to B in these events is a few meters per second. This is marginal at best for seeding the Rayleigh‐Taylor instability. However, larger‐amplitude events may be masked by the development of the plumes themselves. All but two events found thus far occurred at night but the daytime cases are fascinating since the E region is expected to short out such fields.
Constraints on mantle flow at the Caribbean–South American plate boundary inferred from shear wave splitting
Authors: Growdon Mark A. , Pavlis Gary L. , Niu Fenglin , Vernon Frank L. , Rendon Herbert
Published: February 2009

We measured shear wave splitting from SKS and SKKS data recorded by temporary stations deployed as part of the Broadband Onshore‐Offshore Lithospheric Investigation of Venezuela and the Antilles Arc Region project and the national seismic network of Venezuela. Approximately 3000 station‐event pairs yielded ∼300 with visible SKS and/or SKKS phases. We obtained 63 measurements at 39 of the 82 stations in the network using the method of Silver and Chan (1991) and conventional quality criteria. We combined our results with previous measurements made by Russo et al. (1996). The most prominent feature in the data is an area of large (>2.0 s) lag times with roughly east–west fast axes in northeastern Venezuela. Mineral physics models show split times this large are difficult to explain with horizontal foliation, but are more feasible with anisotropy characterized by a coherent vertical foliation and an east–west fast axis extending over most of the upper 250 km of the mantle. We interpret the large split times in northeastern Venezuela as a consequence of eastward translation of the Atlantic slab, which has left a strong vertical foliation in its wake parallel to the plate boundary. The peak split times correspond closely with the point the slab intersects the base of the anisotropic asthenosphere at 250 km. Away from this area of large split times the measured times fall to more standard values, but an east–west fast axis still predominates. We suggest this is linked to the rapidly varying strain field at the southern edge of the Atlantic which quickly disrupts the coherent strain field that causes the very large split times in northeastern Venezuela.
Variations in the Malvinas Current volume transport since October 1992
Authors: Spadone Aurélie , Provost Christine
Published: February 2009

We present a set of new current meter measurements collected to monitor the Malvinas Current (MC) near its merger with the Brazil Current at 40–41°S from December 2001 to February 2003 below a Jason‐1 altimeter track. These measurements are compared to former measurements obtained 8 years earlier at the same location; they also provide new information on the core of the MC on the continental slope above the 1000‐m isobath where a mooring had been previously lost. There, most of the velocity variation is along‐isobath (80% of the variance) and shows a significant annual cycle. The two data sets provide coherent means and statistical parameters on the vertical structure of the flow. A 14‐year‐long time series of MC volume transport is derived using satellite altimetry. The good correlation between the altimetry‐derived transport and the transport estimated from the current meter data persists in time (over 0.7 for each measurement period). A spectacular shift in the spectral composition of transport variations was observed: from 1992 until the end of 1997 transport variations occurred at rather short periods (50–90 days and to some degree around 180 days) whereas, after year 2000, longer periods including a seasonal cycle predominated. Altimetry‐derived anomalies of surface geostrophic velocities along the core of the MC show a similar shift in spectral composition suggesting a remote‐forcing origin.
On the influence of anthropogenic forcings on changes in the stratospheric mean age
Authors: Oman Luke , Waugh Darryn W. , Pawson Steven , Stolarski Richard S. , Newman Paul A.
Published: February 2009

A common feature of stratospheric simulations of the past or future is an increase in tropical upwelling and a decrease in mean age. Possible causes of these changes include (1) increases in tropical sea surface temperatures (SSTs) driven by increases in well‐mixed greenhouse gases (WMGHGs), (2) the direct radiative effect of increases in WMGHGs, and (3) changes in ozone. Here we examine a suite of simulations from the Goddard Earth Observing System chemistry‐climate model (GEOS CCM) to isolate the relative role of these three factors. Our analysis indicates that all three factors cause changes in the mean age, but the relative impact of each factor depends on the time period analyzed. Over the past 30–40 years ozone depletion is the major factor causing the decrease in mean age, with negligible changes due to direct radiative impact of WMGHGs. However, ozone is predicted to recover back to 1970 levels during the next 50–60 years, and this causes an increase in the mean age, whereas the continued increase in SSTs from increased levels of WMGHGs and the direct radiative impact of WMGHGs will still cause a decrease in the mean age. The net impact of these factors will still result in a decreasing mean age although the rate will be smaller than that of the past. The decreases in mean age are primarily caused by increases in upwelling in the tropical lower stratosphere. The increased upwelling from both increased tropical SSTs and polar ozone loss appears to be related to changes in zonal winds and increases in wave activity propagating into the stratosphere. The different contributions of changes in SSTs, WMGHGs, and ozone to the circulation of the stratosphere may help explain the large spread in the rate of change of tropical upwelling seen in previous studies.
The M‐type receptor PLA2R regulates senescence through the p53 pathway
Authors: Augert Arnaud , Payré Christine , de Launoit Yvan , Gil Jesus , Lambeau Gérard , Bernard David
Published: February 2009

Senescence is a stable proliferative arrest induced by various stresses such as telomere erosion, oncogenic or oxidative stress. Compelling evidence suggests that it acts as a barrier against tumour development. Describing new mechanisms that favour an escape from senescence can thus reveal new insights into tumorigenesis. To identify new genes controlling the senescence programme, we performed a loss‐of‐function genetic screen in primary human fibroblasts. We report that knockdown of the M‐type receptor PLA2R (phospholipase A2 receptor) prevents the onset of replicative senescence and diminishes stress‐induced senescence. Interestingly, expression of PLA2R increases during replicative senescence, and its ectopic expression results in premature senescence. We show that PLA2R regulates senescence in a reactive oxygen species–DNA damage–p53‐dependent manner. Taken together, our study identifies PLA2R as a potential new tumour suppressor gene crucial in the induction of cellular senescence through the activation of the p53 pathway.
Magnetocaloric effect in Fe–Zr–B–M (M=Mn, Cr, and Co) amorphous systems
Authors: Fang Y. K. , Yeh C. C. , Hsieh C. C. , Chang C. W. , Chang H. W. , Chang W. C. , Li X. M. , Li. W.
Published: February 2009

The magnetocaloric effect (MCE) of the amorphous Fe–Zr–B–M (M=Mn, Cr, and Co) ribbons has been investigated. The MCEs of the Fe90−xZr10Bx (x=5, 10, 15, and 20) ribbons are enhanced with small amounts of boron addition. Furthermore, the Curie temperature of the specimens can be decreased to be about room temperature with appropriate Mn and Cr substitutions, but the MCE performance of the specimens drops only slightly. It is also found that the magnetic entropy change of the Co-substitution series of Fe85−yZr10B5Coy ribbons almost remains constant although the Curie temperature is increased to be about 400K for y=5. Therefore, for the application of MCE refrigeration at above room temperature, the Fe85−yZr10B5Coy ribbons are preferred due to the constant MCE and the high refrigeration capacity of about 90J∕kg at the magnetic field change of 10kOe. Moreover, the field dependence of the magnetic entropy change exhibits power dependence for all the studied specimens. In the ferromagnetic range, the exponent is close to 1. In the paramagnetic regime, well above the Curie temperature, the exponent is 2, in agreement with the Curie–Weiss law.
Confined quantum systems and their limits
Authors: Belgiorno Francesco , Gallone Franco
Published: February 2009

In nonrelativistic quantum mechanics, the notion of the confined version of a system is proposed and discussed. Confined observables can turn out to be represented by just positive operator valued measures also when their nonconfined equivalents are represented by self-adjoint operators, and this nearly always happens for confined linear momentum observables. However, the self-adjoint operators of the nonconfined system can still be used to compute expected results and variances of confined observables. As a result, the precision with which some confined observables can be measured has limits which ultimately derive, through the Heisenberg commutation rules, from the covariance properties of nonconfined kinematical observables. Two conditions are proposed to characterize the approximation of a nonconfined system by a sequence of confined ones. A nonconfined system is deemed to be approximated by a sequence of confined systems if all probabilities determined by any observable of the nonconfined system with respect to nonconfined states can be approximated by confined counterparts and if the time evolution of any state of the nonconfined system can be approximated in any finite time interval by the time evolution of confined states. A rather general example of this situation is discussed.
Langmuir probe characterization of laser ablation plasmas
Authors: Doggett Brendan , Lunney James G.
Published: February 2009

For laser ablation plumes that are significantly ionized, Langmuir probes have proved to be a useful tool for measuring the plume shape, ion energy distribution, and electron temperature. Typically in laser ablation plasmas the flow velocity is supersonic, which complicates the interpretation of the current-voltage probe characteristic. In this paper we describe some recent developments on the application of Langmuir probes for laser ablation plume diagnosis. We have investigated the behavior of the probe when it is orientated perpendicular, and parallel, to the plasma flow, and show how an analytical model developed for plasma immersion ion implantation, can quantitatively describe the variation of the ion current with probe bias for the case when the plasma flow is along the probe surface. The ion signal recorded by a probe in the parallel position is proportional to the ion density and the square root of the bias voltage. It is shown that the current varies as mi−1/2 so that by comparing the ion signals from the parallel and perpendicular positions it is possible to estimate the mass of the ions detected. We have also determined the temporal variation of electron temperature. A planar probe oriented parallel to the plasma flow, where the ion current due to the plasma flow is eliminated, gives a more reliable measurement of Te (<0.6 eV). The measured Te is consistent with the measured ion current, which is dependent on Te when the time taken for an element of plasma to traverse the probe is longer than the time taken for the matrix ion sheath extraction phase.
The dielectric and tunable properties of Mn doped (Ba0.6Sr0.4)0.925K0.075TiO3 thin films fabricated by sol-gel method
Authors: Sun Xiaohua , Feng Ping , Zou Jun , Wu Min , Zhao Xing-zhong
Published: February 2009

( Ba 0.6 Sr 0.4 ) 92.5 % K 7.5 % TiO 3 (BSKT) thin films doped by Mn from 0 to 6 mol % were fabricated by the sol-gel method on a Pt/TiO2/SiO2/Si substrate. The structure and surface morphology of Mn-doped BSKT thin films were investigated as a function of Mn concentration by x-ray diffraction and scanning electron microscopy. The dielectric measurements were conducted on metal-insulator-metal capacitors at the frequency from 100 Hz to 1 MHz at room temperature. It was found that the Mn concentration in Mn doped BSKT thin films has a strong influence on material properties including surface morphology and dielectric and tunable properties. Increasing Mn content leads to simultaneous decreasing of surface roughness, dielectric constant, and tunability of Mn doped BSKT films. However the dielectric loss of Mn doped BSKT decreases first and then increases with the increase in Mn dopant. The effects of Mn doping on the microstructure and dielectric and tunable properties of Mn doped BSKT thin films were analyzed. (Ba0.6Sr0.4)92.5%K7.5%TiO3 thin films show the highest dielectric constant and tunability to be 1040 and 73.6%, respectively. However, the 1 mol % Mn doped BSKT thin films with the smallest dielectric loss and upper tunability are the best choice for tunable device applications for its highest figure of merit value of 37.5.
Torque ripple minimization of flux-controllable stator-permanent-magnet brushless motors using harmonic current injection
Authors: Zhu Xiaoyong , Cheng Ming , Chau K. T. , Yu Chuang
Published: February 2009

Due to the nature of salient poles in both the stator and rotor, the new class of flux-controllable stator-permanent-magnet brushless (FC-SPMBL) motors still suffers from severe torque ripples. In this paper, a new torque ripple minimization approach, namely, the harmonic current injection method, is proposed and implemented in the FC-SPMBL motor. By injecting proper harmonic current components into the fundamental current, the variation of instantaneous power is kept to minimum. Thus, the torque ripple is minimized. Both simulation and experimental results show that the proposed approach can effectively suppress the torque ripple.
Theoretical study on the stability of magnetic structures in the surface and interfaces of Heusler alloys, Co2MnAl and Co2MnSi
Authors: Sakuma A. , Toga Y. , Tsuchiura H.
Published: February 2009

We carry out the first principles calculations for bulk, surface, and bilayer system of Heusler alloys Co2MnAl and Co2MnSi. In the bulk system, the Mn moments feel much larger exchange (molecular) field than the Co moments. In the surface density of states of Co, the half-metallicity disappears in both systems, even though the magnetic moments are enhanced due to localization of d-states. The exchange constant of the surface Co is much reduced in Co2MnSi. In the bilayer system with MgO, both the magnetic moments and exchange constants of Co atoms at the interface are remarkably decreased. We suppose that such instability of Co moments at the interface is responsible for the strong dependences of the magnetoresistance ratio on both the temperature and bias voltage, which was measured in the magnetic tunnel junction of Co2MnAl(Si)∕MgO.
Utilizing particle swarm Optimization in the field computation of nonlinear media subject to mechanical stress
Authors: Adly A. A. , Abd-El-Hafiz S. K.
Published: February 2009

It is well known that applied mechanical stresses could have a strong adverse effect on the magnetic properties of ferromagnetic media. In power devices, mechanical clamping mechanisms of core lamination stacks could, thus, alter their overall performance. This paper presents an automated approach through which field computation of nonlinear media subject to mechanical stress may be performed. In this approach, clamped zones are assumed to posses zero strain and magnetization induced stresses are deduced from prohibited magnetostriction. Details of the approach as well as simulation results are given in the paper.
Magnetorheological carbonyl iron particles doubly wrapped with polymer and carbon nanotube
Authors: Ko S. W. , Lim J. Y. , Park B. J. , Yang M. S. , Choi H. J.
Published: February 2009

To improve magnetorheological (MR) characteristics of carbonyl iron (CI) microparticles, we introduce two-step CI coating procedures with poly(methyl methacrylate) (PMMA) and multiwalled carbon nanotube (MWNT) for the first time. Core(CI)-shell(PMMA) (CI-PM) structured composite magnetic microbeads were synthesized by dispersion polymerization first, showing improved dispersion stability and sedimentation quality. However, its magnetic strength was decreased compared with that of pristine CI-based MR fluid. To enhance its magnetic strength, the core-shell type CI-PM particles were wrapped with MWNT via ultrasonication. Rheological properties of their MR fluid were measured by a rotational rheometer with a magnetic field supplier. The CI-PMMA-MWNT (CI-PM-NT) particles were found to show better flow and dynamic rheological properties compared to those from CI-PM particles while density of the CI-PM-NT particles was not much different from that of CI-PM, implying that sedimentation stability of the CI-PM-NT particles was also being kept.
Magnetic properties of SrTiO3-buffered Ba(Fe0.2Zr0.8)O3−δ films on Si(001) substrates
Authors: Kanatani H. , Kume H. , Matsui T.
Published: February 2009

Ba ( Fe 0.2 Zr 0.8 ) O 3 − δ (BFZO) films were synthesized on Si(001) substrates using SrTiO3 (STO) buffer layers by pulsed laser-beam deposition method. The results of the x-ray diffraction revealed that the STO buffer layers and the BFZO films had polycrystalline nature. The STO-buffered BFZO films showed ferromagnetic hysteresis loops at room temperature, and their saturation magnetization was 3.3 times as large as that of the BFZO films directly deposited on Si(001) substrates. The STO-buffered BFZO films partially grew epitaxially on the STO buffer layers with orientation relationships. The results of the x-ray photoelectron spectroscopy analysis using soft x-ray radiation indicated that the relative amount of the Fe4+ ions fairly increased for the STO-buffered BFZO films rather than for the BFZO films directly deposited on Si substrates.
Magnetic properties of M-doped (M=Mn, Cr, or V) ZnSiN2
Authors: Rufinus Jeff
Published: February 2009

The current interest in the emerging field of semiconductor spintronics is mostly focused on transition-metal-doped binary materials, e.g., Mn-doped GaAs, GaN, etc. Recently, however, the explorations of transition-metal-doped ternary semiconductors have intensified due to some experimental confirmations of high Curie temperature in chalcopyrite compounds. In ternary materials, there are possibilities of having ferromagnetic or antiferromagnetic configurations, depending on which metal site was substituted by the dopant. A density functional theory within generalized gradient approximation study was performed on M-doped (M=Mn, Cr, or V) ternary material ZnSiN2. The objective of this study is to determine whether substitutional transition metal in a group II (Zn) site and in a group IV (Si) site will be ferromagnetic or antiferromagnetic. The results show both Mn- and Cr-doped ZnSiN2 to be antiferromagnetic if (Mn, Cr) substitute Zn site and ferromagnetic if (Mn, Cr) substitute Si site. On the other hand, V-doped ZnSiN2 was found to be ferromagnetic, independent of the substitution sites.
Synthesis and magnetic properties of gold coated iron oxide nanoparticles
Authors: Pal Susmita , Morales Marienette , Mukherjee Pritish , Srikanth Hariharan
Published: February 2009

We report on synthesis, structural, and magnetic properties of chemically synthesized iron oxide (Fe3O4) and Fe3O4@Au core-shell nanoparticles. Structural characterization was done using x-ray diffraction and transmission electron microscopy, and the magnetite phase of the core (∼6nm) and fcc Au shell (thickness of ∼1nm) were confirmed. Magnetization (M) versus temperature (T) data at H=200Oe for zero-field-cooled and field-cooled modes exhibited a superparamagnetic blocking temperature TB∼35K (40K) for parent (core-shell) system. Enhanced coercivity (Hc∼200Oe) at 5K along with nonsaturating M-H loops observed for Fe3O4@Au nanoparticles indicate the possible role of spin disorder at the Au–Fe3O4 interface and weak exchange coupling between surface and core spins. Analysis of ac susceptibility (χ′ and χ″) data shows that the interparticle interaction is reduced upon Au coating and the relaxation mechanism follows the Vogel–Fulcher law.
Phase transitions in Er1−xLuxFe2O4
Authors: Kim J. , Ahn J. S. , Jung C. U. , Kim C. S. , Lee B. W.
Published: February 2009

Phase transitions have been investigated for polycrystalline samples of Er1−xLuxFe2O4 (0⩽x⩽0.6). The magnetization measurements for ErFe2O4 showed two-step phase transitions at about 220 and 250K. The transition at 250K is an antiferromagnetic transition and that at 220K is a structural transition. However, two phase transitions do not occur for 0.2⩽x⩽0.6, but a thermoremanent magnetization is observed below 220K. This indicates that there is no second phase transition for 0.2⩽x⩽0.6.
Fabrication of MgO-based magnetic tunnel junctions with CoCrPt perpendicularly magnetized electrodes
Authors: Watanabe Daisuke , Mizukami Shigemi , Oogane Mikihiko , Naganuma Hiroshi , Ando Yasuo , Miyazaki Terunobu
Published: February 2009

The applicability of perpendicularly magnetized CoCrPt films to the MgO-based magnetic tunnel junctions (MTJs) was investigated. For this study, CoCrPt films deposited on the Ru buffer exhibited hcp(0002)-oriented growth by sputtering method using the low substrate temperature of 250 °C, low saturation magnetization of around 360 emu/cm3, and high magnetic anisotropy field of 6 kOe, which is sufficient to retain the thermal stability of the magnetization direction. The MgO-based MTJs with a synthetic ferrimagnetlike structure were fabricated: CoFe was coupled magnetically with CoCrPt through the thin Ru layer. Transport properties with a magnetic field applied perpendicular to the film plane revealed a tunnel magnetoresistance ratio of about 6% at room temperature.
Magnetic circular dichroism spectroscopy in epitaxial La0.7Sr0.3MnO3 thin films
Authors: Nath T. K. , Neal J. R. , Gehring G. A.
Published: February 2009

Magneto-optic measurements are a very powerful tool for investigating the polarization of a conduction band as a function of temperature and are used here to study the polarization of the mobile electrons in 500 Å La0.7Sr0.3MnO3 strained thin films grown epitaxially on single crystalline (001) LaAlO3 (LAO) and (001) La0.3Sr0.7Al0.65Ta0.35O9 substrates. The magnetic circular dichroism (MCD) has been investigated in magnetic fields up to 0.5 T and over a temperature range (10–450 K). The MCD spectra of both the films show a peak at the band gap at around 3 eV and the peak is found to be shifted toward lower energy side with the increase in temperature. A separate polaron peak (well known in insulating samples) appears at lower energy (∼1.8 eV) with the increase in temperature in all these metallic films. The rapid decrease in conduction band polarization in the film on LAO has strong implications for the use of these manganites in room temperature spintronics.
Ferromagnetism in pure wurtzite zinc oxide
Authors: Zuo Xu , Yoon Soack-Dae , Yang Aria , Duan Wen-Hui , Vittoria Carmine , Harris Vincent G.
Published: February 2009

The ferromagnetism induced by the intrinsic point defects in wurtzite zinc oxide is studied by using ab initio calculation based on density functional theory. The calculations show that both oxygen interstitial and zinc vacancy may induce ferromagnetism into this material. The calculations also show that zinc oxide with oxygen interstitial may be a ferromagnetic semiconductor. Based on the simplified electronic configuration of the defect molecules, we explain the total magnetic moment, electronic structure, and ferromagnetism.
Does ferroelectric polarization in LiCu2O2 uniquely originate from spiral spin order?
Authors: Qin M. H. , Guo Y. J. , Dong S. , Wang K. F. , Liu J.-M.
Published: February 2009

We perform Monte Carlo simulation of the ferroelectricity induced by spiral spin order in spin-1/2 LiCu2O2 based on the Mostovoy phenomenological theory. The simulated spiral spin order parameter and ferroelectric polarization, respectively, as a function of temperature and magnetic field are compared with recent experiments. The substantial differences in several aspects of the multiferroicity between the simulation and experiments allow a reasonable argument that the spiral spin order may not be the unique origin for the ferroelectricity generation.
Digital magnetic tagging for multiplexed suspension-based biochemical assays
Authors: Mitrelias T. , Trypiniotis T. , Palfreyman J. J. , Hong B. , Vyas K. , Hayward T. J. , Llandro J. , Kopper K. P. , Bland J. A. C. , Robertson P. A. , Barnes C. H. W.
Published: February 2009

Microarrays and suspension (or bead)-based technologies have attracted significant interest for their broad applications in high throughput molecular biology. However, the throughput of microarrays will always be limited by the array density and the slow diffusion of molecules to their binding sites. Suspension-based technologies, in which all the reactions take place directly on the surface of microcarriers functionalized with molecular probes, could offer true multiplexing due to the possibility of extending their detection capability by a straightforward expansion of the size of the chemical library of probes. To fully exploit their potential, the microcarriers must be tagged, but the number of distinct codes available from spectrometric/graphical/physical encoding methods is currently fairly limited. A digital magnetic tagging method based on magnetic microtags, which have been anisotropy engineered to provide stable magnetization directions which correspond to digital codes, is reported. The tags can be suspended in solution and functionalized with a variety of biological molecular probes. Magnetic tagging offers several benefits compared to the traditional optical encoding techniques currently employed. It offers minimal background signals, potential for a large number of distinct codes, miniaturization of devices, and the ability to write a code in situ. Experimental data showing the reading of individual magnetic microbars from samples comprising 50×20 μm2 Ni elements, as well as micromagnetic simulations that show the feasibility of stray field detection, are presented. The stray fields of the magnetic microbars spanning a range of 60 mOe were detected by a microfabricated fluxgate sensor scanned in a raster fashion over the sample that was placed about 70 μm away. Free floating tags have also been fabricated for use in microfluidic systems. A magnetic lab-on-a-chip device could be used for tagging biomolecular probes for applications in genome sequencing, immunoassays, clinical diagnostics, drug discovery, and general pathogen detection and screening.
Magnetic ordering in the rare earth intermetallic compound Tb2Ti3Ge4: Magnetization and neutron diffraction studies
Authors: Malik S. K. , Lamsal Jagat , de Almeida R. L. , Quezado S. , Yelon W. B. , Garlea V. O. , Morozkin A. V. , Nirmala R.
Published: February 2009

Magnetization and neutron diffraction studies on a polycrystalline Tb2Ti3Ge4 sample (orthorhombic Sm5Ge4-type structure, space group Pnma, No. 62) have been carried out. This compound is found to order antiferromagnetically at ∼18 K (TN). The magnetization (M) versus field (H) isotherms obtained at 2, 3, 5, and 10 K indicate a field-induced antiferromagnetic to ferromagnetic transition in fields of the order of 0.5 T. The saturation magnetization value at 2.5 K (M extrapolated to 1/H→0) is only ∼5.6μB/Tb3+, suggesting the possible presence of crystal field effects with or without a persisting antiferromagnetic component. Neutron powder diffraction data at 10 K confirm the existence of a magnetic long range order. Modeling of the magnetic scattering reveals a complex and incommensurate antiferromagnetic spin structure below TN.
Simulation of the time dependent infrared ν2 mode absorptions of (oH2)n:H2O clusters in O2 doped solid hydrogen at 4.2K
Authors: Abouaf-Marguin L. , Vasserot A.-M. , Pardanaud C.
Published: February 2009

Using Fourier transform infrared spectroscopy, we have analyzed the time evolution of the ν2 mode of (oH2)n:H2O clusters (n=11 to 1) embedded in solid normal hydrogen at 4.2K over a period of 150h using paramagnetic O2 to speed up the ortho to para nuclear spin conversion process. For concentrations H2O∕O2∕H2=1∕20∕4000, at time t=0 right after the solid is prepared, all the H2O molecules are preferentially clustered by large numbers of oH2. With time the cluster distribution irreversibly shifts toward smaller cluster sizes and also generates freely rotating H2O (n=0) which is solvated completely by pH2 molecules. From a spectral decomposition of the ν2 (oH2)n:H2O cluster spectra, a phenomenological simulation of the time behavior of the clusters has been developed. The time evolution is modeled using coupled rate equations in a step by step n to n−1 cluster cascade fashion and analyzed over nine successive time periods. It shows that rotating H2O grows only at the expense of cluster n=1 and that the process dramatically slows down as the conversion of orthohydrogen proceeds. At the end of the conversion process, it was found that cluster n=1 remained with a very slow decrease.
Morphological investigation of monodispersed manganese ferrite nanoparticles by the impedance measurement
Authors: Yoon Sunghyun , Gonzales-Weimuller M. , Lee Y.-C. , Krishnan Kannan M.
Published: February 2009

Particle size distributions in manganese ferrite ferrofluids are analyzed based on ac susceptibility measurements. The frequency dependence of the complex susceptibility, χ″(ω), of the ferrofluid was measured by the slit-toroid technique. The sample exhibited frequency response due to Néel’s rotational relaxation, from which the particle size was estimated. A modified log-normal distribution is used for fitting the experimental results, which allows proper account of the narrow distributions. The calculated average particle size is in good agreement with transmission electron microscopy result.
Yet another 3D quadratic autonomous system generating three-wing and four-wing chaotic attractors
Authors: Wang L.
Published: February 2009

This paper introduces a new three-dimensional quadratic autonomous system, which can generate a pair of double-wing chaotic attractors. More importantly, this new system can generate three-wing and four-wing chaotic attractors with very complicated topological structures over a large range of parameters. Several issues, such as some basic dynamical behaviors, bifurcations, and the dynamical structure of the new chaotic system, are investigated either analytically or numerically.