bluuebunny/crossref_metadata_2025 huggingface dataset:
Docosahexaenoic acid-rich fish oil improves heart rate variability and heart rate responses to exercise in overweight adults
Authors: Ninio Daniel M. , Hill Alison M. , Howe Peter R. , Buckley Jonathan D. , Saint David A.
Published: March 2008

Dietary fish oil supplementation and regular physical activity can improve outcomes in patients with established CVD. Exercise has been shown to improve heart rate variability (HRV), a predictor of cardiac death, but whether fish oil benefits HRV is controversial. Obese adults at risk of future coronary disease have impaired HRV and may benefit from these interventions. We evaluated the effect of DHA-rich tuna fish oil supplementation with and without regular exercise on HRV in sedentary, overweight adults with risk factors for coronary disease. In a randomised, double-blind, parallel comparison, sixty-five volunteers consumed 6 g fish oil/d (DHA 1·56 g/d, EPA 0·36 g/d) or sunflower-seed oil (placebo) for 12 weeks. Half of each oil group also undertook regular moderate physical activity (3 d/week for 45 min, at 75 % of age-predicted maximal heart rate (HR)). Resting HR and the HR response to submaximal exercise were measured at weeks 0, 6 and 12. In forty-six subjects, HRV was also assessed by power spectrum analysis of 20 min electrocardiogram recordings taken supine at baseline and 12 weeks. Fish oil supplementation improved HRV by increasing high-frequency power, representing parasympathetic activity, compared with placebo (P = 0·01; oil ×  time interaction). It also reduced HR at rest and during submaximal exercise (P = 0·008; oil ×  time interaction). There were no significant fish oil ×  exercise interactions. Dietary supplementation with DHA-rich fish oil reduced HR and modulated HRV in keeping with an improved parasympathetic–sympathetic balance in overweight adults with risk factors for future coronary disease.
Protest Leadership in Rural China
Authors: Li Lianjiang , O'brien Kevin J.
Published: March 2008

Rural protest leaders in China play a number of roles. Among others, they lead the charge, shape collective claims, recruit activists and mobilize the public, devise and orchestrate acts of contention, and organize cross-community efforts. Protest leaders emerge in two main ways. Long-standing public figures initiate popular action on their own or in response to requests from other villagers; and ordinary villagers evolve into protest leaders when efforts to seek redress for a personal grievance fail. Rural officials sometimes attempt to co-opt or buy off protest leaders, but more often turn to repression. Although cracking down may inhibit further contention, at other times it firms up the determination of protest leaders and makes them more prone to adopt confrontational tactics, partly by enhancing their popular support, partly by increasing the costs of withdrawal.
Local Governments and the Suppression of Popular Resistance in China
Authors: Cai Yongshun
Published: March 2008

Local governments are responsible for dealing with many of the instances of resistance in China, and an important mode of response which they use is suppression. This article examines the rationale behind local governments' use of this mode of response. It shows that Chinese citizens who stage resistance are in a weak legal position because their actions often violate the law or government regulations. Given local governments' discretion in interpreting citizens' action, suppression becomes the option when concessions are difficult to make and citizen resistance threatens social stability, policy implementation or local officials' images. However, suppression has not stopped popular resistance, and it remains a channel through which citizens defend or pursue their legitimate rights in China.
Reconsidering the Campaign to Suppress Counterrevolutionaries
Authors: Kuisong Yang
Published: March 2008

Power seized with violence has to be maintained with violence. This truth has been repeatedly proved in the course of the founding of the Chinese Communist Party. The suppression of the counterrevolutionary movement in the 1950–53 period was the first campaign launched by the PRC aimed at cleansing opposition elements. This article re-examines Mao Zedong's policies and practices, and the interaction between China's central and local authorities during the campaign. It assesses whether the campaign met its goals and its implications for the future use of suppression by the regime.
Governance Reform towards “Serving Migrant Workers”: The Local Implementation of Central Government Regulations
Authors: Davies Gloria , Ramia Gaby
Published: March 2008

Using data from three provinces as part of a joint study by Monash University in Australia and China's Institute of Labour Science, an affiliate body of the national Ministry of Labour and Social Security, this article examines the extension of social rights and social security coverage to intra-national migrants in China as a public governance issue. More specifically, it analyses how central government regulations on improving the situation of migrant workers are being interpreted and implemented by local governments. In this regard, it offers a unique case study of difficulties encountered in the local implementation of policy directives issued by the central government.
China's 2004 Economic Census and 2006 Benchmark Revision of GDP Statistics: More Questions than Answers?
Authors: Holz Carsten A.
Published: March 2008

In 2006, China's National Bureau of Statistics undertook a benchmark revision of national income and product accounts statistics based on the findings of the 2004 economic census. The benchmark revision covers primarily the years 1993–2004 with revised economy-wide and sectoral output values. The new data have three implications. First, despite all the hype only a few years ago about data falsification by local statistical authorities in China, the 2004 economic census results validate the provincial aggregate output values and invalidate the centre's national ones. Second, at the national level, economy-wide as well as sectoral nominal values were revised but real growth rates of some sectors remained unchanged. That is not plausible, and implies that at least the secondary sector real growth rates are erroneous. And finally, the benchmark revision raises questions about the quality and meaning of a large body of official statistics. Ultimately, it casts doubt on the professionalism and sincerity of China's statistical authority.
Surgery in older people: an update
Authors: Harari D , Dhesi J
Published: March 2008

In the past two decades, the rate of surgery in older people has increased more rapidly than the rate of aging of the population, so both a larger proportion and a greater number of older people are now undergoing surgery. This may partly reflect a cultural change in surgery and anaesthesia with respect to a greater willingness to undertake elective procedures in older people, although there remain areas where they have less access to surgery than do younger patients. For instance, older people are less likely to undergo operative procedures after a cancer diagnosis. Furthermore, in those who do have surgery, resection rate (i.e. curative therapy) is lower than in younger people with equivalent tumour stages, and even more so in older patients with COPD, cardiovascular disease or diabetes. This article explores the complex relationship between age and surgical outcome, provides an evidence-based overview of risk assessment and common postoperative problems in older people, and summarizes good practice points (at times necessarily pragmatic) for clinical management of the older surgical patient. There has been a substantial expansion in the literature examining risks, outcomes and interventions in older surgical patients since the previous review article of this subject published in this journal. Although we do not cover anaesthesia in older people, the review of that topic remains relevant. The American Society of Anaesthesiologists' Classification of Risk which illustrates that risk is disease- rather than age- based, is shown in Table 1. Most publications examine elective rather than emergency surgery in older people (with the exception of hip fracture), and this is reflected in the content of the paper.
Appropriate prescribing in older people
Authors: Mukhopadhyay Indranil , Lally Frank , Crome Peter
Published: March 2008

As people age they almost invariably develop diseases which lead to the prescription of drugs – both to prevent disease progression and for symptomatic relief. Unfortunately, drug treatment in later life is also problematic. There is a dearth of evidence on the efficacy of drugs in people over the age of 80, and members of this age group are at highest risk of adverse drug reactions (ADR).
Vertical sorting and the morphodynamics of bed form‐dominated rivers: A sorting evolution model
Authors: Blom Astrid , Ribberink Jan S. , Parker Gary
Published: March 2008

Existing sediment continuity models for nonuniform sediment suffer from a number of shortcomings, as they fail to describe vertical sorting fluxes other than through net aggradation or degradation of the bed and are based on a discrete representation of the bed material interacting with the flow. We present a new type of sediment continuity model that is based on a stochastic description of the bed surface rather than discrete bed layers. The model is aimed at conditions dominated by bed load transport wherein the river bed is fully covered by river dunes. Application of the model should be limited to spatial scales covering a significant number of bed forms. The resulting model, i.e., the sorting evolution model, is suitable for unsteady conditions, as it takes into account the time evolution of, for instance, vertical sorting in modeling net aggradation or degradation of the river bed. The present paper lists the various submodels of a morphodynamic model system to which the sorting evolution model is applied. We compare the results of the morphodynamic model system to measured data from two flume experiments. The new model shows reasonable results for the predicted time evolution of the vertical sorting profile, as well as the time evolution of the grain size distribution of the bed load transport. Yet the model does not properly include sorting mechanisms associated with partial transport and the winnowing of fines from the trough surface and subsurface. The model serves as a basis for a future simplification of the model into a new stochastics‐based bed layer type sediment continuity model in which vertical sediment fluxes are included in a parameterized way.
Benthic Foraminiferal response to sea level change in the mixed siliciclastic‐carbonate system of southern Ashmore Trough (Gulf of Papua)
Authors: Carson Brooke E. , Francis Jason M. , Leckie R. Mark , Droxler André W. , Dickens Gerald R. , Jorry Stéphan J. , Bentley Sam J. , Peterson Larry C. , Opdyke Bradley N.
Published: March 2008

Ashmore Trough in the western Gulf of Papua (GoP) represents an outstanding modern example of a tropical mixed siliciclastic‐carbonate depositional system where significant masses of both river‐borne silicates and bank‐derived neritic carbonates accumulate. In this study, we examine how benthic foraminiferal populations within Ashmore Trough vary in response to sea level–driven paleoenvironmental changes, particularly organic matter and sediment supply. Two 11.3‐m‐long piston cores and a trigger core were collected from the slope of Ashmore Trough and dated using radiocarbon and oxygen isotope measurements of planktic foraminifera. Relative abundances, principal component analyses, and cluster analyses of benthic foraminiferal assemblages in sediment samples identify three distinct assemblages whose proportions changed over time. Assemblage 1, with high abundances of Uvigerina peregrina and Bolivina robusta, dominated between ∼83 and 70 ka (early regression); assemblage 2, with high abundances of Globocassidulina subglobosa, dominated between ∼70 and 11 ka (late regression through lowstand and early transgression); and assemblage 3, with high abundances of neritic benthic species such as Planorbulina mediterranensis, dominated from ∼11 ka to the present (late transgression through early highstand). Assemblage 1 represents heightened organic carbon flux or lowered bottom water oxygen concentration, and corresponds to a time of maximum siliciclastic fluxes to the slope with falling sea level. Assemblage 2 reflects lowered organic carbon flux or elevated bottom water oxygen concentration, and corresponds to an interval of lowered siliciclastic fluxes to the slope due to sediment bypass during sea level lowstand. Assemblage 3 signals increased off‐shelf delivery of neritic carbonates, likely when carbonate productivity on the outer shelf (Great Barrier Reef) increased significantly when it was reflooded. Benthic foraminiferal assemblages in the sediment sink (slopes of Ashmore Trough) likely respond to the amount and type of sediment supplied from the proximal source (outer GoP shelf).
Validation of liquid cloud property retrievals from SEVIRI using ground‐based observations
Authors: Roebeling R. A. , Placidi S. , Donovan D. P. , Russchenberg H. W. J. , Feijt A. J.
Published: March 2008

Partly due to aerosol effects stratocumulus clouds vary considerably in liquid water path (LWP), geometrical thickness (h) and droplet number concentration (Nc). Cloud models have been developed to simulate h and Nc using satellite retrieved cloud optical thickness (τ) and effective radius (re) values. In this paper we examine the consistency between LWP and h values inferred from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) onboard METEOSAT‐8. The use of METEOSAT‐8 data means that time series of LWP and h can be validated at a 15‐minute resolution, and used for examining the first indirect aerosol effect. For single‐layered stratocumulus clouds the LWP and h retrievals from SEVIRI are compared to corresponding ground‐based observations at two Cloudnet sites. A study on the sensitivity of the cloud model to the uncertainties in SEVIRI retrievals of τ and re reveals that h and Nc simulations are only accurate for clouds with effective radii larger than 5 μm. The SEVIRI and ground‐based retrievals of LWP and h show very good agreement, with accuracies of about 15 g m−2 and 20 m, respectively. This agreement could only be achieved by assuming sub‐adiabatic profiles of droplet concentration and liquid water path in the cloud model. The degree of adiabaticity for single‐layered stratocumulus clouds could be quantified by simultaneous analysis of SEVIRI and ground‐based LWP and h values, which suggests that stratocumulus clouds over North Western Europe deviate, on average, from adiabatic clouds.
Interactions of wind‐transported snow with a rift in the Ross Ice Shelf, Antarctica
Authors: Leonard Katherine C. , Tremblay L.‐Bruno , MacAyeal Douglas R. , Jacobs Stanley S.
Published: March 2008

Rifts in ice shelves accumulate a mélange of snow and firn from above and marine ice from below, material that has been postulated to negatively influence iceberg calving. From measurements and modeling we show that a 100 m wide rift near the front of the Ross Ice Shelf captures all wind‐transported snow traveling in saltation and a substantial fraction of the snow blowing in suspension across the rift. Moderate winds and snow transport appear sufficient to fill the rift in several years, whereas the mélange surface profile remains relatively constant within the 30 m deep rift. Observed subsidence and ocean temperatures in the rift suggest that net basal melting dissolves the mélange from below, limiting its effectiveness as an anti‐calving agent near ice fronts.
Trends in Antarctic annual sea ice retreat and advance and their relation to El Niño–Southern Oscillation and Southern Annular Mode variability
Authors: Stammerjohn S. E. , Martinson D. G. , Smith R. C. , Yuan X. , Rind D.
Published: March 2008

Previous studies have shown strong contrasting trends in annual sea ice duration and in monthly sea ice concentration in two regions of the Southern Ocean: decreases in the western Antarctic Peninsula/southern Bellingshausen Sea (wAP/sBS) region and increases in the western Ross Sea (wRS) region. To better understand the evolution of these regional sea ice trends, we utilize the full temporal (quasi‐daily) resolution of satellite‐derived sea ice data to track spatially the annual ice edge advance and retreat from 1979 to 2004. These newly analyzed data reveal that sea ice is retreating 31 ± 10 days earlier and advancing 54 ± 9 days later in the wAP/sBS region (i.e., total change over 1979–2004), whereas in the wRS region, sea ice is retreating 29 ± 6 days later and advancing 31 ± 6 days earlier. Changes in the wAP/sBS and wRS regions, particularly as observed during sea ice advance, occurred in association with decadal changes in the mean state of the Southern Annular Mode (SAM; negative in the 1980s and positive in the 1990s) and the high‐latitude response to El Niño–Southern Oscillation (ENSO). In general, the high‐latitude ice‐atmosphere response to ENSO was strongest when ‐SAM was coincident with El Niño and when +SAM was coincident with La Niña, particularly in the wAP/sBS region. In total, there were 7 of 11 ‐SAMs between 1980 and 1990 and the 7 of 10 +SAMs between 1991 and 2000 that were associated with consistent decadal sea ice changes in the wAP/sBS and wRS regions, respectively. Elsewhere, ENSO/SAM‐related sea ice changes were not as consistent over time (e.g., western Weddell, Amundsen, and eastern Ross Sea region), or variability in general was high (e.g., central/eastern Weddell and along East Antarctica).
Spatial and temporal changes in the concentration of various phosphorus pools and their possible biogeochemical roles in the oligotrophic subtropical western North Pacific
Authors: Lee Sangkyun , Hama Takeo , Ishii Masao , Saito Shu , Yanagi Katsumi
Published: March 2008

Spatial and temporal variations in the concentration of phosphorus pools, including total phosphorus (TP), reactive phosphorus (RP), and nonreactive phosphorus (NP), were evaluated in subtropical regions (10–30°N) of the western North Pacific Ocean along 137°E through eight sampling periods from summer 2003 to spring 2005. RP was depleted at the water surface throughout our observation, varying less than 0.1 μM. The low concentration of RP was restricted to the surface mixing layer, and the concentration obviously increased concomitant with the decrease in water temperature. NP concentration was generally highest at the water surface and gradually decreased with increasing depth, but the depth and temporal variations were not definite compared with those of RP. NP was further divided into two fractions depending on its reactivity to specific ultraviolet (UV) irradiation. The concentration of UV labile organic phosphorus (UVL OP) was consistently low, being comparable with that of RP; their inventories from 0 to 50 m of RP and UVL OP fluctuated with in the range of 0.9–3.2 and 2.0–3.1 mmol m−2, respectively. As for incubation experiments in coastal waters using glucose‐1‐phosphate, which is fractionated into UVL OP, the UVL OP most likely has a short turnover time due to rapid utilization by microorganisms, indicating a significant role in the phosphorus cycle through the microbial food web. Inventory of the UV stable OP (UVS OP), on the other hand, varied nearly eightfold in the upper 50 m, and the temporal change in TP inventory was exclusively due to that of UVS OP.
Satellite‐derived variability in chlorophyll, wind stress, sea surface height, and temperature in the northern California Current System
Authors: Venegas Roberto M. , Strub P. Ted , Beier Emilio , Letelier Ricardo , Thomas Andrew C. , Cowles Timothy , James Corinne , Soto‐Mardones Luis , Cabrera Carlos
Published: March 2008

Satellite‐derived data provide the temporal means and seasonal and nonseasonal variability of four physical and biological parameters off Oregon and Washington (41°–48.5°N). Eight years of data (1998–2005) are available for surface chlorophyll concentrations, sea surface temperature (SST), and sea surface height, while six years of data (2000–2005) are available for surface wind stress. Strong cross‐shelf and alongshore variability is apparent in the temporal mean and seasonal climatology of all four variables. Two latitudinal regions are identified and separated at 44°–46°N, where the coastal ocean experiences a change in the direction of the mean alongshore wind stress, is influenced by topographic features, and has differing exposure to the Columbia River Plume. All these factors may play a part in defining the distinct regimes in the northern and southern regions. Nonseasonal signals account for ∼60–75% of the dynamical variables. An empirical orthogonal function analysis shows stronger intra‐annual variability for alongshore wind, coastal SST, and surface chlorophyll, with stronger interannual variability for surface height. Interannual variability can be caused by distant forcing from equatorial and basin‐scale changes in circulation, or by more localized changes in regional winds, all of which can be found in the time series. Correlations are mostly as expected for upwelling systems on intra‐annual timescales. Correlations of the interannual timescales are complicated by residual quasi‐annual signals created by changes in the timing and strength of the seasonal cycles. Examination of the interannual time series, however, provides a convincing picture of the covariability of chlorophyll, surface temperature, and surface height, with some evidence of regional wind forcing.
Seasonal dependence of Interball flux transfer events
Authors: Korotova G. I. , Sibeck D. G. , Rosenberg T.
Published: March 2008

J. Raeder (2006) presented the results of a global magnetohydrodynamic simulation indicating that flux transfer events (FTEs) form solely in the winter hemisphere and move poleward in the direction of the background magnetosheath flow during periods of strongly southward interplanetary magnetic field (IMF) orientation. This paper presents results from a statistical survey of flux transfer FTEs observed on the mid‐latitude northern and southern magnetopause by the magnetometer on the Interball‐1 spacecraft over the course of its five‐year mission from 1995 to 1999. Interball‐1 observations confirm that FTEs exhibit a strong tendency to occur in the winter hemisphere.
Improved group-specific PCR primers for denaturing gradient gel electrophoresis analysis of the genetic diversity of complex microbial communities
Authors: Mühling Martin , Woolven-Allen John , Murrell J Colin , Joint Ian
Published: March 2008

Phylum- and class-specific PCR primers were tested for the production of clone libraries and for denaturing gradient gel electrophoresis (DGGE) analysis of complex bacterial communities. Primers were designed to specifically amplify 16S rRNA gene fragments of the phyla Bacteroidetes, Planctomycetes and Firmicutes, of three classes of the phylum Proteobacteria, the Alphaproteobacteria, Betaproteobacteria and Gammaproteobacteria, and of the Cyanobacteria (including chloroplast 16S rRNA genes). The specificity of the seven primer pairs was tested by producing clone libraries from environmental DNA samples from mesotrophic (Norwegian coastal) and oligotrophic (Northern Atlantic Gyre) environments. Five of the seven primer pairs specifically amplified target 16S rRNA gene sequences. Exceptions were the Betaproteobacteria- and Firmicutes-specific primers, which were relatively successful with coastal water mesocosm samples but less so with the Northern Atlantic Gyre sample. Phylogenetic analysis of sequences from the Gammaproteobacteria clone library revealed that the coastal sample yielded a number of clones that clustered within clades that belong to the oligotrophic marine Gammaproteobacteria (OMG) group, indicating that this group is not confined exclusively to the oligotrophic environment. Comparison of the bacterial diversity of the environmental DNA sample from the coastal and the open ocean using a two- or three-step nested PCR-DGGE process revealed significant differences in the bacterial communities. The application of the group-specific primers provides a higher resolution genetic fingerprinting approach than existing DGGE primer sets.
Exploring the correlation between network structure and electron binding energy in the (H2O)7− cluster through isomer-photoselected vibrational predissociation spectroscopy and ab initio calculations: Addressing complexity beyond types I-III
Authors: Roscioli Joseph R. , Hammer Nathan I. , Johnson Mark A. , Diri Kadir , Jordan Kenneth D.
Published: March 2008

We report a combined photoelectron and vibrational spectroscopy study of the (H2O)7− cluster anions in order to correlate structural changes with the observed differences in electron binding energies of the various isomers. Photoelectron spectra of the (H2O)7−⋅Arm clusters are obtained over the range of m=0–10. These spectra reveal the formation of a new isomer (I′) for m>5, the electron binding energy of which is about 0.15eV higher than that of the type I form previously reported to be the highest binding energy species [Coe et al., J. Chem. Phys. 92, 3980 (1990)]. Isomer-selective vibrational predissociation spectra are obtained using both the Ar dependence of the isomer distribution and photochemical depopulation of the more weakly (electron) binding isomers. The likely structures of the isomers at play are identified with the aid of electronic structure calculations, and the electron binding energies, as well as harmonic vibrational spectra, are calculated for 28 low-lying forms for comparison with the experimental results. The HOH bending spectrum of the low binding type II form is dominated by a band that is moderately redshifted relative to the bending origin of the bare water molecule. Calculations trace this feature primarily to the bending vibration localized on a water molecule in which a dangling H atom points toward the electron cloud. Both higher binding forms (I and I′) display the characteristic patterns in the bending and OH stretching regions signaling electron attachment primarily to a water molecule in an AA binding site, a persistent motif found in non-isomer-selective spectra of the clusters up to (H2O)50−.
Application of geometric algebra for the description of polymer conformations
Authors: Chys Pieter
Published: March 2008

In this paper a Clifford algebra-based method is applied to calculate polymer chain conformations. The approach enables the calculation of the position of an atom in space with the knowledge of the bond length (l), valence angle (θ), and rotation angle (φ) of each of the preceding bonds in the chain. Hence, the set of geometrical parameters {li,θi,φi} yields all the position coordinates pi of the main chain atoms. Moreover, the method allows the calculation of side chain conformations and the computation of rotations of chain segments. With these features it is, in principle, possible to generate conformations of any type of chemical structure. This method is proposed as an alternative for the classical approach by matrix algebra. It is more straightforward and its final symbolic representation considerably simpler than that of matrix algebra. Approaches for realistic modeling by means of incorporation of energetic considerations can be combined with it. This article, however, is entirely focused at showing the suitable mathematical framework on which further developments and applications can be built.
N
O
2
dissociation on Ag(111) revisited by theory
Authors: Hellman Anders , Panas Itai , Grönbeck Henrik
Published: March 2008

N O 2 dissociation on Ag(111) is investigated with first-principles calculations. For single NO2 molecules, a high adsorption potential energy is found to prohibit dissociation. This result is surprising as experiments indicate dissociation at low temperatures. Neither entropy effects nor irregularities in the potential energy surface can remedy the discrepancy. Instead it is proposed that collective Eley-Rideal type of reaction mechanisms can drive the dissociation.
The use of global modes to understand transition and perform flow control
Authors: Henningson Dan S. , Åkervik Espen
Published: March 2008

The stability of nonparallel flows is considered using superposition of global modes. When perturbed by the worst case initial condition, these flows often exhibit a large transient growth associated with the development of wave packets. The global modes of the systems also provide a good starting point for the design of reduced order models used to control the growing disturbances. Three recent investigations are reviewed. The first example is the growth of a wave packet on a falling liquid sheet. The optimal perturbation analysis shows that the worst case initial condition is a localized disturbance that creates a propagating wave packet that hits the downstream end, regenerating a wave packet upstream through a global pressure pulse. Second, we consider two-dimensional disturbances in the Blasius boundary layer. It is found that a wave packet is optimally excited by an initial condition consisting of localized backward leaning Orr structures. Finally, the control of a globally unstable boundary-layer flow along a shallow cavity is considered. The disturbance propagation is associated with the development of a wave packet along the cavity shear layer, unstable to the Kelvin–Helmholtz mechanism, followed by a global cycle related to the two unstable global modes. Direct numerical simulations of this flow are coupled to a measurement feedback controller, which senses the wall shear stress at the downstream lip of the cavity and provides the actuation at the upstream lip. A reduced order model for the control is obtained by a projection on the least stable global eigenmodes. The linear-quadratic-Gaussian controller is run in parallel to the Navier–Stokes time integration and it is shown to damp out the global oscillations.
Hysteretic behavior of angular dependence of exchange bias in FeNi∕FeMn bilayers: A new signature
Authors: Shi Z. , Gao T. R. , Zhou S. M. , Chantrell R. , Asselin P. , Bai X. J. , Du J. , Wu X. S.
Published: March 2008

As a new signature, the hysteretic behavior of angular dependence of exchange bias in FeNi∕FeMn bilayers is studied as function of the constituent layer thickness. When the FeMn layer is thin enough, there is no hysteretic behavior. When the FeMn layer thickness is increased, the hysteretic effect reaches a maximum sharply and then decreases slowly as the FeMn layer thickness is further increased. It is independent of the ferromagnet layer thickness. This new phenomenon implies a thermally driven evolution of the magnetic state in the antiferromagnet layer.
Structural, magnetic, and magneto-optical properties of Co-doped CeO2−δ films
Authors: Bi Lei , Kim Hyun-Suk , Dionne Gerald F. , Speakman Scott A. , Bono D. , Ross C. A.
Published: March 2008

Magnetically doped CeO2 is a promising dilute magnetic semiconductor and may also be useful in magneto-optical applications. Ce1−xCoxO2−δ (x=0, 0.02, 0.06, 0.15, and 0.25) films were deposited by pulsed laser deposition on MgO(100) substrates and their structural, magnetic, and magneto-optical properties were characterized. The films show a textured ceria single phase with (111) preferred orientation. All the Co-doped samples show room temperature ferromagnetism and large magnetic anisotropy with an out-of-plane easy axis. Magneto-optical measurements indicate that the Co-doped films also have high saturation Faraday rotation ranging from 230to6000deg∕cm depending on the Co concentration, and their refractive index and extinction coefficient also increase with Co concentration.
Experimental and theoretical studies of the CN–Ar van der Waals complex
Authors: Han Jiande , Heaven Michael C. , Schnupf Udo , Alexander Millard H.
Published: March 2008

The CN–Ar van der Waals complex has been observed using the BΣ+2−XΣ+2 and AΠ2−XΣ+2 electronic transitions. The spectra yield a dissociation energy of D0″=102±2cm−1 and a zero-point rotational constant of B0″=0.067±0.005cm−1 for CN(X)–Ar. The dissociation energy for CN(A)–Ar was found to be D0′=125±2cm−1. Transitions to vibrationally excited levels of CN(B)–Ar dominated the B-X spectrum, indicative of substantial differences in the intermolecular potential energy surfaces (PESs) for the X and B states. Ab initio PESs were calculated for the X and B states. These were used to predict rovibrational energy levels and van der Waals bond energies (D0″=115 and D0′=183cm−1). The results for the X state were in reasonably good agreement with the experimental data. Spectral simulations based on the ab initio potentials yielded qualitative insights concerning the B-X spectrum, but the level of agreement was not sufficient to permit vibronic assignment. Electronic predissociation was observed for both CN(A)–Ar and CN(B)–Ar. The process leading to the production of CN(A,ν=8,9) fragments from the predissociation of CN(B,ν=0)–Ar was characterized using time-resolved fluorescence and optical-optical double resonance measurements.
Hydrophobic solvation of Gay–Berne particles in modified water models
Authors: Head-Gordon Teresa , Lynden-Bell Ruth M.
Published: March 2008

The solvation of large hydrophobic solutes, modeled as repulsive and attractive Gay–Berne oblate ellipsoids, is characterized in several modified water liquids using the SPC/E model as the reference water fluid. We find that small amounts of attraction between the Gay–Berne particle and any model fluid result in wetting of the hydrophobic surface. However, significant differences are found among the modified and SPC/E water models and the critical distances in which they dewet the hydrophobic surfaces of pairs of repulsive Gay–Berne particles. We find that the dewetting trends for repulsive Gay–Berne particles in the various model liquids correlate directly with their surface tensions, the widths of the interfaces they form, and the openness of their network structure. The largest critical separations are found in liquids with the smallest surface tensions and the broadest interfaces as measured by the Egelstaff–Widom length.
Classical and quantum mechanical/molecular mechanical molecular dynamics simulations of alanine dipeptide in water: Comparisons with IR and vibrational circular dichroism spectra
Authors: Kwac Kijeong , Lee Kyung-Koo , Han Jae Bum , Oh Kwang-Im , Cho Minhaeng
Published: March 2008

We have implemented the combined quantum mechanical (QM)/molecular mechanical (MM) molecular dynamics (MD) simulations of alanine dipeptide in water along with the polarizable and nonpolarizable classical MD simulations with different models of water. For the QM/MM MD simulation, the alanine dipeptide is treated with the AM1 or PM3 approximations and the fluctuating solute dipole moment is calculated by the Mulliken population analysis. For the classical MD simulations, the solute is treated with the polarizable or nonpolarizable AMBER and polarizable CHARMM force fields and water is treated with the TIP3P, TIP4P, or TIP5P model. It is found that the relative populations of right-handed α-helix and extended β and PII conformations in the simulation trajectory strongly depend on the simulation method. For the QM/MM MD simulations, the PM3/MM shows that the PII conformation is dominant, whereas the AM1/MM predicts that the dominant conformation is αR. Polarizable CHARMM force field gives almost exclusively PII conformation and other force fields predict that both α-helical and extended (β and PII) conformations are populated with varying extents. Solvation environment around the dipeptide is investigated by examining the radial distribution functions and numbers and lifetimes of hydrogen bonds. Comparing the simulated IR and vibrational circular dichroism spectra with experimental results, we concluded that the dipeptide adopts the PII conformation and PM3/MM, AMBER03 with TIP4P water, and AMBER polarizable force fields are acceptable for structure determination of the dipeptide considered in this paper.
Spin-dependent diffraction at ferromagnetic/spin spiral interface
Authors: Manchon A. , Ryzhanova N. , Vedyayev A. , Dieny B.
Published: March 2008

Spin-dependent transport is investigated in ballistic regime through the interface between a ferromagnet and a spin spiral. We show that spin-dependent interferences lead to a new type of diffraction called “spin diffraction.” It is shown that this spin diffraction leads to local spin and electrical currents along the interface. This study also shows that in highly nonhomogeneous magnetic configuration (nonadiabatic limit), the contribution of the diffracted electrons is crucial to describe spin transport in such structures.
Generation and orientation of organoxenon molecule H–Xe–CCH in the gas phase
Authors: Poterya Viktoriya , Votava Ondřej , Fárník Michal , Ončák Milan , Slavíček Petr , Buck Udo , Friedrich Břetislav
Published: March 2008

We report on the first observation of the organoxenon HXeCCH molecule in the gas phase. This molecule has been prepared in a molecular beam experiment by 193nm photolysis of an acetylene molecule on Xen clusters (n¯≈390). Subsequently the molecule has been oriented via the pseudo-first-order Stark effect in a strong electric field of the polarized laser light combined with the weak electrostatic field in the extraction region of a time-of-flight spectrometer. The experimental evidence for the oriented molecule has been provided by measurements of its photodissociation. For comparison, photolysis of C2H2 on Arn clusters (n¯≈280) has been measured. Here the analogous rare gas molecule HArCCH could not be generated. The interpretation of our experimental findings has been supported by ab initio calculations. In addition, the experiment together with the calculations reveals information on the photochemistry of the HXeCCH molecule. The 193nm radiation excites the molecule predominantly into the 2Σ+1 state, which cannot dissociate the Xe–H bond directly, but the system evolves along the Xe–C coordinate to a conical intersection of a slightly nonlinear configuration with the dissociative 1Π1 state, which then dissociates the Xe–H bond.
Relationship between tunnel magnetoresistance and magnetic layer structure in EuO-based tunnel junctions investigated using polarized neutron reflectivity
Authors: Watson S. M. , Santos T. S. , Borchers J. A. , Moodera J. S.
Published: March 2008

This paper presents a study of the depth-dependent magnetic structure of a EuO magnetic tunnel junction having a Gd electrode, Si∕Cu∕EuO∕Gd∕Al. Related samples that are patterned exhibit large tunneling magnetoresistance as high as 280%. Though Gd has a much higher coercivity than EuO in bulk, magnetometry reveals no “steps” in the hysteresis loop as expected for a true antiparallel alignment of the EuO and Gd layer magnetizations. Using polarized neutron reflectometry to measure the structural and field-dependent magnetic depth profile at 5K, we determine that the Gd and EuO layers have similar coercivities and that the Gd layer exhibits an anomalously small magnetization at all fields. Polarized neutron reflectometry results also suggest that the chemical density of the Gd layer is not that of bulk Gd. The differences of the structural and magnetic behavior of the Gd layer relative to bulk may be the key in optimizing the tunnel magnetoresistance in these samples.
Reduction of switching current distribution in spin transfer magnetic random access memories
Authors: Iwayama M. , Kai T. , Nakayama M. , Aikawa H. , Asao Y. , Kajiyama T. , Ikegawa S. , Yoda H. , Nitayama A.
Published: March 2008

In this paper, the switching current distribution by spin transfer torque is investigated for CoFeB∕MgO∕CoFeB magnetic tunnel junctions (MTJs). The distribution of the spin transfer switching current for a MTJ with junction size of 85×110nm2 is 16% when the duration of applied pulse current is 5ms. In the case of magnetization reversal with magnetic field induced by current with 5ms pulse duration, the distribution of the switching field is 8.3%. According to our micromagnetic simulation, it is found that the spin transfer current switching seems to exhibit a nonuniform magnetization reversal process, whereas the magnetization switching by the magnetic field exhibits a uniform magnetization reversal process. This leads to the broader distribution related to the repeatability.
Comparison of electromagnetic performance of brushless motors having magnets in stator and rotor
Authors: Hua Wei , Cheng Ming , Zhu Z. Q. , Zhao Wenxiang , Kong Xiangxin
Published: March 2008

The electromagnetic performance of two permanent magnet brushless motors, viz., flux-switching magnet (FSPM) and surface-mounted motors, in which concentrated stator windings are employed but the magnets are located in the stator and the rotor, respectively, is investigated by the finite element analysis. The significant differences in topologies and static characteristics are highlighted. The results show that both motors exhibit sinusoidal back-emf waveform and the FSPM motor exhibits not only larger airgap flux density, higher torque per copper loss, but also higher torque ripple due to cogging torque.
Modeling of fast switching processes in nanoscale spin valves
Authors: Carpentieri M. , Finocchio G. , Torres L. , Azzerboni B.
Published: March 2008

Braganca et al. [Appl. Phys. Lett. 87, 112507 (2005)] fabricated spin valves (permalloy/copper/permalloy) with elliptical cross-sectional area designed to reduce the critical currents for spin-transfer switching maintaining its thermal stability. We performed a numerical experiment in that spin valve to study how the switching time is affected by saturation magnetization and damping. Those parameters can be experimentally tuned by changing the alloy percentage or by introducing impurities. We find out the switching time and the switching mechanism are independent of those parameters for nanosecond reversal processes.
The design evaluation of inductive power-transformer for personal rapid transit by measuring impedance
Authors: Han Kyung-Hee , Lee Byung-Song , Baek Soo-Hyun
Published: March 2008

The contact-less inductive power transformer (IPT) uses the principle of electromagnetic induction. The concept of the IPT for vehicles such as the personal rapid transit (PRT) system is proposed and some suggestions for power collector design of IPT to improve power transfer performance are presented in this paper. The aim of this paper is to recommend the concept of IPT for vehicles such as the PRT system and also to present some propositions for the power collector design of the IPT, which is to improve the power transfer performance. Generally, there are diverse methods to evaluate transfer performance of the traditional transformers. Although the principle of IPT is similar to that of the general transformer, it is impossible to apply the methods directly because of large air gap. The system must be compensated by resonant circuit due to the large air gap. Consequently, it is difficult to apply numerical formulas to the magnetic design of IPT systems. This paper investigates the magnetic design of a PRT system using three-dimensional magnetic modeling and measurements of the pick-up coupling coefficient and its impedances. In addition, how the use of Litz wire and leakage inductance is related will be observed through experiment and simulation.
Photoelastic effects in Pb(Mg1/3Nb2/3)O3−29%PbTiO3 single crystals investigated by Hertzian contact experiments
Authors: Di Na , Harker John C. , Quesnel David J.
Published: March 2008

Photoelastic effects in small single-crystal Pb(Mg1/3Nb2/3)O3−29%PbTiO3 (PMN–29%PT) samples were investigated by Hertzian contact experiments. The experiments were performed on samples having various crystallographic orientations. The resulting photoelastic fringe patterns were observed to be strongly dependent on the orientation of the samples, showing that pseudocubic unpoled PMN–29%PT single crystals have highly anisotropic elastic properties. Annealing above the Curie temperature was found to completely remove the fringe patterns created by the Hertzian indentation experiments. In addition, three-dimensional simulations of the Hertzian contact experiments were performed using ANSYS®. The simulations used cubic-form elastic constants calculated from data on poled PMN–30%PT single crystals. The ANSYS® modeling results were comparable to the experimentally observed fringe patterns, suggesting that the elastic properties of pseudocubic unpoled PMN–PT single crystals may resemble those of pseudotetragonal poled PMN–PT single crystals. This resemblance is considered significant because of the uniqueness of the growth direction during seeded crystal growth. ANSYS® provided a reliable method for qualitative simulation of photoelastic effects in unpoled PMN–PT single crystals under mechanical loading.
Solvation of O2− and O4− by p-difluorobenzene and p-xylene studied by photoelectron spectroscopy
Authors: Kang Cheolhwa , Troyer Jenny L. , Robertson Erika M. , Rothgeb David W. , Hossain Ekram , Wyrwas Richard B. , Parmenter Charles S. , Jarrold Caroline Chick
Published: March 2008

Anion photoelectron spectra of the O2−⋅arene and O4−⋅arene complexes with p-xylene and p-difluorobenzene are presented and analyzed with the aid of calculations on the anions and corresponding neutrals. Relative to the adiabatic electron affinity of O2, the O2−⋅arene spectra are blueshifted by 0.75–1eV. Solvation energy alone does not account for this shift, and it is proposed that a repulsive portion of the neutral potential energy surface is accessed in the detachment, resulting in dissociative photodetachment. O2− is found to interact more strongly with the p-difluorobenzene than the p-xylene. The binding motif involves the O2− in plane with the arene, interacting via electron donation along nearby C–H bonds. A peak found at 4.36(2)eV in the photoelectron spectrum of O2−⋅p-difluorobenzene (p-DFB) is tentatively attributed to the charge transfer state, O2−⋅p-DFB+. Spectra of O4−⋅arene complexes show less blueshift in electron binding energy relative to the spectrum of bare O4−, which itself undergoes dissociative photodetachment. The striking similarity between the profiles of the O4−⋅arene complexes with the O4− spectrum suggests that the O4− molecule remains intact upon complex formation, and delocalization of the charge across the O4− molecule results in similar structures for the anion and neutral complexes.
Selective photodissociation in diatomic molecules by dynamical Stark-shift control
Authors: Choi Hyeonho , Son Won-Joon , Shin Seokmin , Chang Bo Y. , Sola Ignacio R.
Published: March 2008

Selective population transfer in electronic states of dissociative molecular systems is illustrated by adopting a control scheme based on Stark-chirped rapid adiabatic passage (SCRAP). In contrast to the discrete N-level system, dynamical Stark shift is induced in a more complex manner in the molecular electronic states. Wavepacket dynamics on the light-induced potentials, which are determined by the detuning of the pump pulse, can be controlled by additional Stark pulse in the SCRAP scheme. Complete population transfer can be achieved by either lowering the energy barrier along the adiabatic passage or placing the initial wavepacket on a well-defined dressed state suitable for the control. The determination of the pulse sequence is sufficient for controlling population transfer to the target state.