bluuebunny/crossref_metadata_2025 huggingface dataset:
Dominant controls on pesticide transport from tile to catchment scale: Lessons from a minimalist model
Authors: Zanardo S. , Basu N. B. , Botter G. , Rinaldo A. , Rao P. S. C.
Published: March 2012

This paper proposes a minimalist modeling approach for characterizing pesticide concentrations in runoff from agricultural catchments across spatial scales. The model proposed is of an intermediate level of complexity between traditional chromatographic separation models and the more complex dual‐domain models. Parsimony in the model is achieved by assuming stationarity of catchment travel time distributions and by coupling a dual‐domain source zone model that describes near‐surface pesticide dynamics with the mass response function (MRF) approach, which describes catchment‐scale solute transport. The model is evaluated by comparing predicted atrazine concentrations with measured values over a 5 yr period at two spatial scales (tile drain: 3–5 ha; river station: 69 km2) within an intensively managed agricultural catchment in Illinois, United States. Pesticide dynamics within the source zone provided the strongest control on leaching. Two parameters were calibrated at the tile scale, Γ, which describes partitioning in the dual‐domain surficial source zone, and ke, which describes the mass transfer rate constant between the two domains. The initial peak of concentration was found to be sensitive to Γ, while the later peaks were sensitive to ke. The calibrated parameters at the tile stations were used to predict atrazine dynamics at the river station. Prediction errors are examined and related to the lack of detailed information about anthropogenic forcings across scales (e.g., land‐use or soil/crop management practices).
Modeling of ionospheric magnetic field perturbations induced by earthquakes
Authors: Imtiaz Nadia , Marchand Richard
Published: March 2012

The objective of this study is to present a simple coupled seismo‐ionospheric model to account for magnetic field perturbations in response to geophysical phenomena such as Earthquakes or tsunamis. For this purpose, we include a simple gravity wave model in the two dimensional mid latitude ionosphere model SAMI2. Following an earthquake, the disturbances in the neutral atmosphere density and velocity associated with gravity waves propagate vertically upward up to ionospheric altitudes 150–350 km, where significant coupling between the neutral atmosphere and the ionosphere occurs. As a result, a rapid variation in the ionospheric plasma density and temperature is observed associated with the photoionization of the perturbed neutral density. This variation in the electron density leads in turn to a variation in the total electron content (TEC). Strong variations in the TEC are observed close to the epicenter which correspond to large plasma density perturbations in this region associated with the ion acoustic mode. The calculation of magnetic perturbations is based on a set of reduced MHD equations. These are solved numerically using the finite element code TOPO coupled with the mid latitude ionospheric model SAMI2. The coupling between the two codes accounts for the variations in neutral gas density and the collisional drag force between ions and neutrals. Two wave modes are considered: the shear Alfvén mode and the compressional mode. The results of the magnetic field perturbations and of ions' velocity perturbations associated with the shear Alfvén and the compressional modes are presented. Variations in the TEC values are also computed for the compressional mode by taking into account the density perturbations transverse to the magnetic field. The results representing TEC perturbations associated with the compressional mode show strong variations at high latitudes both as a function of time and latitude.
Autoimmunity: innovation in pathogenesis and therapy
Authors: Thomas Ranjeny
Published: March 2012

Autoimmunity occurs when an organism develops an immune response against itself, resulting in an inflammatory reaction which damages organs such as brain, joints or pancreas. This results in diseases such as Type 1 diabetes, vasculitis, or rheumatoid arthritis. A fine balance exists in order to accommodate the control of microbial pathogens and commensals, and immune self‐tolerance. The March 2012 issue will include a review series on Autoimmune Disease, particularly featuring articles on clinical translation, and the current state of research in this area. Articles include reasons for the increased incidence of certain autoimmune diseases and allergic diseases in Western society and the advances made by the application of novel and high throughput technologies to the analysis of diseased tissues. The accompanying web focus presents links to related articles from across Nature Publishing Group.
BMI Predicts Emotion‐Driven Impulsivity and Cognitive Inflexibility in Adolescents With Excess Weight
Authors: Delgado‐Rico Elena , Río‐Valle Jacqueline S. , González‐Jiménez Emilio , Campoy Cristina , Verdejo‐García Antonio
Published: March 2012

Adolescent obesity is increasingly viewed as a brain‐related dysfunction, whereby reward‐driven urges for pleasurable foods “hijack” response selection systems, such that behavioral control progressively shifts from impulsivity to compulsivity. In this study, we aimed to examine the link between personality factors (sensitivity to reward (SR) and punishment (SP), BMI, and outcome measures of impulsivity vs. flexibility in—otherwise healthy—excessive weight adolescents. Sixty‐three adolescents (aged 12–17) classified as obese (n = 26), overweight (n = 16), or normal weight (n = 21) participated in the study. We used psychometric assessments of the SR and SP motivational systems, impulsivity (using the UPPS‐P scale), and neurocognitive measures with discriminant validity to dissociate inhibition vs. flexibility deficits (using the process‐approach version of the Stroop test). We tested the relative contribution of age, SR/SP, and BMI on estimates of impulsivity and inhibition vs. switching performance using multistep hierarchical regression models. BMI significantly predicted elevations in emotion‐driven impulsivity (positive and negative urgency) and inferior flexibility performance in adolescents with excess weight—exceeding the predictive capacity of SR and SP. SR was the main predictor of elevations in sensation seeking and lack of premeditation. These findings demonstrate that increases in BMI are specifically associated with elevations in emotion‐driven impulsivity and cognitive inflexibility, supporting a dimensional path in which adolescents with excess weight increase their proneness to overindulge when under strong affective states, and their difficulties to switch or reverse habitual behavioral patterns.
Parent Predictors of Child Weight Change in Family Based Behavioral Obesity Treatment
Authors: Boutelle Kerri N. , Cafri Guy , Crow Scott J.
Published: March 2012

Family based behavioral treatment for overweight and obese children includes parenting skills targeting the modification of child eating and activity change. The purpose of this study was to examine parenting skills and parent weight change as predictors of child weight change in a sample of 80 parent/child dyads who were enrolled in a family based behavioral weight loss program for childhood obesity. Eighty overweight and obese children and their parents who enrolled in treatment in two sites were included in the study. Variables included those related to parent modeling (parent BMI), home food environment, parenting (parent and child report), and demographics. Results suggested that parent BMI change was a significant predictor of child weight, in that a reduction of 1 BMI unit in the parent was associated with a 0.255 reduction in child BMI. None of the other variables were significant in the final model. This study is consistent with other research showing that parent weight change is a key contributor to child weight change in behavioral treatment for childhood obesity. Researchers and clinicians should focus on encouraging parents to lose weight to assist their overweight and obese child in weight management.
Kinetics of moisture uptake and soluble‐solids loss by puffed breakfast cereals immersed in water
Authors: Machado Maria de F́tima , Oliveira Fernanda A. R. , Gekas Vassilia , Singh R. Paul
Published: March 2012

Protein concentrates of some Nigerian underused legume seed flours, lima bean (Phaseolus lunatus L.) and pigeon pea (Cajanus cajan), were prepared by alkaline extraction followed by acid precipitation, whereas that of African yam bean (Sphenotilis sternocarpa) was prepared by acid extraction followed by alkaline precipitation. Simple and objective means that allowed precise determination of the inversion point were used in investigating the capacity of the protein concentrates to emulsify fat. Their relative efficiencies as emulsion stabilizers were also investigated. The results revealed that the emulsifying capacities of these protein concentrates decreased with increasing protein concentration and emulsifying speed. However, emulsifying capacities increased with increasing initial aliquot size, whereas variation of speed of oil addition did not have any significant influence. The capacity of the protein concentrates to emulsify fat decreased in the order pigeon pea protein concentrate > lima bean protein concentrate > African yam bean protein concentrate. But for emulsion stability, the protein concentrates were in the opposite rank order.
‘Divided We Stand’: Sex, Gender and Sexual Difference
Authors: Moore Henrietta
Published: March 2012

This article was originally presented as a paper, and since much of what it discusses turns on problems of position, location, self-representation and representativity, I have decided to leave it, as far as is possible, in its original form. Extensive use of the first person pronoun is frowned on in the contexts in which I am used to working, but I have deliberately retained it in this text to try and convey a sense of particularity, of myself speaking in a specific context(s). The use of ‘we’ is a highly politicized act both in anthropology and in feminist contexts. Its use here is intended to convey a sense of audience, that is of myself speaking to others. But, and much more importantly, it also operates as a mark of interrogation, a fictive unity that reveals the lines of fragmentation at the very moment when it claims affinity.1
Silences: Irish Women and Abortion
Authors: Fletcher Ruth
Published: March 2012

This article considers the forces which act to prevent women in Ireland from speaking about their experiences of abortion. It considers the various forms such silencing can take and the complexity of feelings and circumstance which women who have had abortions are subject to. In so doing it raises important questions about the way public debate about abortion between pro-choice and pro-life arguments — couched in terms of rights — acts to further silence women. Finally, the article calls for the creation of a new public and intellectual space in which the complexities of the issues can be realized. A new public space such as this could then facilitate the enactment of permissive legislation which in turn could enable women to decide the best pregnancy option available for them at any particular moment in their lives.
Irish/woman/artwork: Selective Readings
Authors: Robinson Hilary
Published: March 2012

This paper concentrates upon particular artworks from Irish women artists. It demonstrates that there are certain themes which recur in their artwork. These include dislocation, particularities about place and contestation around language, all of which are rooted in the lived experience of being Irish, being female and being an artist. At the same time the paper provides readings of this artwork which demonstrate that these experiences are diverse, and that the areas of representation within which the artists are working are socially produced constructs. There is therefore no romantic essentialist category of ‘Irish woman artist’, but rather the richly interplaying histories, readings and contexts of Irish/woman/artwork.
Negotiating the Politics of Inclusion: Women and Australian Labor Governments 1983 to 1995
Authors: Johnson Carol
Published: March 2012

The Hawke and Keating Labor governments have tended to practise a politics of inclusion in which women, along with other social groups, are seen to have an important part to play in building the new, internationally competitive Australian economy of the twenty-first century, Australian politics have therefore had a very different nature from that of the more exclusionary politics practised by British Conservative governments. While the politics of inclusion have given feminists room for manoeuvre, and facilitated some positive developments in areas such as affirmative action and childcare policies, feminists have had little success in challenging the overall direction of the governments’ right-wing economic policies. Furthermore, the ‘economic’ has functioned as a meta-category which dissolves difference and conflict. The Australian experience therefore has both practical and theoretical implications for British feminists who may be experiencing a Labour government themselves before too long.
Gender, Metaphor and the State
Authors: Sawer Marian
Published: March 2012

The neo-liberal upsurge of the last twenty years and the neo-liberal case against the welfare state has gained much of its emotional force from a sub-text which is highly gendered. Whereas social liberalism had contained the promise of more autonomy within the private sphere and more caring values in the public sphere, neo-liberalism depicts the results of social liberalism as a loss of self reliance – through ‘over-protection’ by the state in the public sphere and usurpation of male roles in the private sphere. The identification of the welfare state as female (the ‘nanny state’) helps fuel resentment on the part of those already confused by rapidly changing gender roles.

This paper tracks the sex change which took place in the image of the liberal state as it evolved out of the night watchman state – the link between the women's suffrage movement and social regulation, maternal principles of distribution and demands for the public organization of caring. It examines the neo-liberal rejection of the breast and neo-liberal claims that the maternal state is incompatible with ‘self-reliance’ and a barrier to competitiveness in the world market.
Unravelling Identities: Performance and Criticism in Australian Feminisms
Authors: Genovese Ann
Published: March 2012

The following article is an exploration of the non-linear and non-unified identities that make up Australian feminism. The main premise is that the divergent strands of rational and romantic thought, central to the project of liberalism, are inherent in the characterization of Australian feminisms. As a result, there have always been tensions between feminists, centred around politics of self-identification. These tensions continue to exist, but to be articulated in different ways in different decades as a result of the ever changing relationships between feminist, state and media/public discourses. These ideas are explored through comparing two key moments in our recent past in which differences between feminisms were declared. These two events – the Mary Daly visit to Australia to promote Gyn/Ecology in 1981, and the debate engendered by Helen Garner's The First Stone in 1995 – are taken to be performative metaphors through which the continuities and discontinuities of the nature of Australian feminisms can be subjectively explored.
Feminism and Sexual Abuse: Troubled Thoughts on some New Zealand Issues
Authors: Guy Camille
Published: March 2012

An anonymous vigilante attack by six women on an Auckland University lecturer in 1984 took place in the context of ongoing feminist reframing of rape and sexual abuse. Most feminists’ responses to this incident assumed the man's guilt and uncritically accepted the allegations made against him. This was not surprising in view of the prescriptive radical feminist hegemony that prevailed in New Zealand throughout the late 1970s and 1980s. Recent feminist writings on sexual harassment have been more ready to grapple with the complexities and ambiguities of issues of sexuality and pedagogy – a shift that enables women to have a wider range of responses to unwanted sexual attention. Some of the earlier and problematic radical feminist notions about rape and sexual abuse have been absorbed into the treatment discourse, with some distressing consequences. In 1988 an over-zealous Christchurch doctor believed she had detected signs of sexual abuse in fifty-six children at a health camp. Her intervention resulted in some girls being removed from their families, even though they denied they had ever been abused. One New Zealand doctor, a pioneer in sexual abuse work in this country, has published a book documenting developments in this area, and expressing grave misgivings about over-intervention and false allegations of abuse. There are persistent attempts to discredit her concerns. However, there is a groundswell of public disquiet over some aspects of sexual abuse work, which cannot be dismissed as backlash.
Queer Black Feminism: The Pleasure Principle
Authors: Harris Laura Alexandra
Published: March 2012

In this critical personal narrative Harris explores some of the gaps between conceptions of feminist thought and feminist practice. Harris focuses on an analysis of race, class, and desire divisions within feminist sexual politics. She suggests a queer black feminist theory and practice that calls into question naturalized identities and communities, and therefore what feminism and feminist practices might entail.
Vera
Authors: Cargan Emily
Published: March 2012

A woman's body found, afternoon, 27 December 1994, in Belfast Lough at Seapark near Holywood, 50–70 years old. Wore a grey tweed coat with a British Legion badge in the lapel and a necklace bearing the name of Vera.
‘To Whom Does Ameena Belong?’
Authors: Mankekar Purnima
Published: March 2012

This article examines the discourses of the Indian state and of community élites during battles for the custody of a young Muslim girl, Ameena, who was ‘rescued’ from a marriage with an elderly Arab. The battles for Ameena's custody were fought as much in news reports, opinion columns, and letters to the editor of metropolitan and vernacular newspapers, as in courts. Questions were raised about Ameena's age, the viability of her marriage, the applicability of secular laws to Muslim communities, and the political economy of the sexuality of girl-children. In these representations, Ameena became a symbol of minority identity, and was transformed into an unwilling and unwitting object of protection.

Why did Ameena's story attract so much attention? What were the different positions underlying the arguments made for Ameena's ‘protection’? Without dismissing the protection of children and the advocacy of their rights, this article analyses the agendas shaping the discourses of the Indian state and national and community élites during the battles for Ameena's custody. The article situates the controversies surrounding Ameena in the wider context of the increasing polarization between Hindu and Muslim communities in India in the early 1990s, and focuses on the relationship between notions of childhood and discourses of community, gender and nation. The article argues that there was a synecdochic relationship between the purity of girl-children and the purity of the Indian nation: far from being ‘pre-cultural’ or apolitical, discourses of childhood were profoundly implicated in the politics of gender, sexuality, community and nation.

What are the implications of Ameena's predicament for feminist epistemology and praxis? In pointing to the ways in which feminist critiques of modernist regimes of power and knowledge can enable us to understand the multiple positionalities of children in the contemporary world, the article explores the spaces available for feminist theorists and activists to engage in a politics of vigilance and intervention with regard to the state's positions towards children.
After the Ivory Tower: Gender, Commodification and the ‘Academic’
Authors: de Groot Joanna
Published: March 2012

This piece uses a feminist approach to explore various aspects of ‘commodification’ in the lives and work of those teaching and researching in UK universities, and in particular its gender dimensions. After setting a historical context for the radical transformation of UK universities during the 1980s, it considers how this transformation was experienced by academics in terms of alienation, anxiety and accountability. Key features of that experience are loss of autonomy and control to the external power of competition and managerialism, insecurity and casualization in employment, and exposure to increasing judgemental scrutiny. For women academics job insecurity and discrimination continue to be disproportionately important, although some of the challenges to old established academic convention and practice have opened up real possibilities to progress more pro-women agendas. In the future they will confront quite depressing developments in the reconstruction of academic identities and labour, but have the legacy of the gains/insights of feminist analysis and politics over the last twenty years with which to do so.
Micromagnetic studies on exchange coupled composite recording media
Authors: Xie Hailong , Li Hongjia , Wang Ying , Zhang Kaiming , Wang Yi , Li Zhenghua , Bai Jianmin , Wei Fulin , Wei Dan
Published: March 2012

The exchange between the hard and soft layer in the exchange coupled composite (ECC) medium is crucial for the recording performance. An accurate micromagnetic model is built for Co-TiO2(4 nm)/Pt(δ = 0−2.8 nm)/CoPt-TiO2 (16 nm) ECC media, based on the microstructure, to investigate the magnetic parameters such as the exchange constant A*3 between the soft/hard layer. In the M-H loops of CoPt-TiO2(16 nm) hard layer, the perpendicular coercivity is 6.1 kOe and the squareness S is 0.98. In ECC media, the thickness δ of interlayer Pt has comprehensive effects on magnetic properties: the coercivity and squareness change little when we just vary A*3 or δ; A*3 equals the intragrain exchange constant A*1 when δ is thinner than grain boundary (≤2 nm); and A*3 decreases from the intergrain exchange constant A*2 to 0 when δ increases from 2.2 to 2.8 nm. The simulation results agree well with experiments.
Size, surface structure, and doping effects on ferromagnetism in SnO2
Authors: Alanko Gordon A. , Thurber Aaron , Hanna Charles B. , Punnoose Alex
Published: March 2012

The effects of crystallite size, surface structure, and dopants on the magnetic properties of semiconducting oxides are highly controversial. In this work, Fe:SnO2 nanoparticles were prepared by four wet-chemical methods, with Fe concentration varying from 0% to 20%. Analysis confirmed pure single-phase cassiterite with a crystallite size of 2.6 ± 0.1 nm that decreased with increasing. Fe% doped substitutionally as Fe3+. Pure SnO2 showed highly reproducible weak magnetization that varied significantly with synthesis method. Interestingly, doping SnO2 with Fe < 2.5% produced enhanced magnetic moments in all syntheses; the maximum of 1.6 × 10−4 µB/Fe ion at 0.1% Fe doping was much larger than the 2.6 × 10−6 µB/Fe ion of pure Fe oxide nanoparticles synthesized under similar conditions. At Fe ≥ 2.5%, the magnetic moment was significantly reduced. This work shows that (1) pure SnO2 can produce an intrinsic ferromagnetic behavior that varies with differences in surface structure, (2) very low Fe doping results in high magnetic moments, (3) higher Fe doping reduces magnetic moment and destroys ferromagnetism, and (4) there is an interesting correlation between changes in magnetic moment, bandgap, and lattice parameters. These results support the possibility that the observed ferromagnetism in SnO2 might be influenced by modification of the electronic structure by dopant, size, and surface structure.
Head-disk interface design in magnetic data storage
Authors: Vemuri Sesha Hari , Chung Pil Seung , Smith Robert L. , Lee Nae-Eung , Biegler Lorenz T. , Jhon Myung S.
Published: March 2012

Superior electrical conductivity and thermo-mechanical response of graphene can significantly improve areal density in magnetic data storage. The current head media spacing in hard disk drives (HDD) is 7.2 nm, and replacing conventional carbon overcoat (COC) with graphene will drastically reduce head media spacing, increasing areal density to eight times its present value. A paradigm shift in HDD systems can also be achieved via selection of a combination of new lubricants and unconventional architecture of COC systems. Here, we evaluate the feasibility of graphene overcoat (GOC), by understanding GOC-lubricant interactions. We further introduce new alternative head-disk interface (HDI) designs consisting of buffer/lubricant layers (i.e., graphene/carbon nanotube (CNT) or fullerene/perfluoropolyether (PFPE)). These hybrids could further enhance tribological performance including the reduction of wear and friction while drastically increasing areal density of data storage devices. Our study here will lead to vigorous investigation of HDI in magnetic data storage, including heat-assisted magnetic recording (HAMR), with tuned atomistic design criteria.
Ferromagnetic resonance analysis of internal effective field of classified grains by switching field for granular perpendicular recording media
Authors: Hinata Shintaro , Saito Shin , Takahashi Migaku
Published: March 2012

The internal effective fields Heff of granular perpendicular magnetic recording media with a switching field (SF) distribution were measured by ferromagnetic resonance (FMR) by sweeping the external field HDC. Heff consists of the anisotropy field Hk, the dipole interaction field, the self-demagnetization field, and the intergranular exchange (coupling) field Hex for up and down magnetic moments of magnetic grains classified by their SF. Prior to the measurement, magnetic grains were classified into two classes: Those with high and low SFs when HDC is swept from +18 kOe to a negative field. FMR measurements were performed in a range for which the same domain structure was retained for typical strong and weak intergranular exchange coupled media (media I and II, respectively). These measurements revealed the following points. (1) Resonances originating from majority-direction moments were observed, whereas those of minority-direction moment were not. (2) The increase in Heff with decreasing 4πM for medium II is larger than that for medium I. (3) Hex can be expressed as Hk − 4πM −Heff when the sum of dipole interaction field and self-demagnetization field is assumed to be the average field 4πM. Hex/Hk was evaluated to be 0.25 (for grains with low SF) and 0.37 (for grains with high SF) for medium I and 0.09 (for both low and high SF) for medium II under M = 0.
Fabrication of scrolled magnetic thin film patterns
Authors: Min Seonggi , Lim Jin-Hee , Gaffney John , Kinttle Kristofer , Wiley John B. , Malkinski Leszek
Published: March 2012

Magnetic film scrolls have been fabricated via a deterministic release of rectangular patterns of bimetallic Ti (20 nm)/Ni (20 , 30 or 40 nm) films from a sacrificial Cu underlayer. The diameter of the scrolls varied from 2.64 μm to 4.28 μm with increasing thickness of the Ni layer from 20 to 40 nm. This behavior was found to be consistent with the model of bilayered film with interfacial strain between the Ti and Ni layers of about Δɛ = 0.01. Changing the geometry of the patterns from flat patterns to scrolls led to changes in their magnetic properties.
Comparison of magnetic and thermoelectric properties of (Nd,Ca)BaCo2O5.5 and (Nd,Ca)CoO3
Authors: Kolesnik S. , Dabrowski B. , Chmaissem O. , Wojciechowski K. , Świerczek K.
Published: March 2012

Magnetic and thermoelectric properties of Nd1−xCaxBaCo2O5.5 and Nd1−xCaxCoO3 have been studied. Ca doping in Nd1−xCaxBaCo2O5.5 (x ≤ 0.2) preserves the metal to insulator transition (MIT) at 340–360 K. While the antiferromagnetic state disappears upon doping, the Curie temperature is increasing and becomes close to MIT for x > 0.12. The magnetic susceptibility of Nd1−xCaxCoO3 is paramagnetic for x up to 0.2, similar to the parent compound, with some indication of cluster-glass-like behavior at temperatures below 30 K. The increasing effective paramagnetic moments with doping suggest a low spin state of Co3+ and a high spin state of Co4+. Maximum observed ZT reaches a value close to 0.2 for x = 0.15 at 800 K, which is one of the highest values for perovskite cobaltites.
Optical transmission modulation by disk-shaped ferromagnetic particles
Authors: Vitol E. A. , Yefremenko V. G. , Jain S. , Pearson J. , Rozhkova E. A. , Bader S. D. , Novosad V.
Published: March 2012

Lithographically defined iron-nickel disks 1 micron in diameter and 60 nm in thickness with a spin-vortex ground state are used to achieve magnetic field-driven light modulation by passing the light through an aqueous solution of magnetic disks with controlled orientations. We demonstrate a significant improvement of the accessible modulation frequency over 60 Hz with a single modulating magnetic field of up to 1 kHz with alternating (ac) bi-directional field.
Analysis of effective permeability behaviors of magnetic hollow fibers filled in composite
Authors: Nam Baekil , Kim Jongryoul , Ki Hyeon Kim
Published: March 2012

In order to predict the permeability behaviors of magnetic hollow fibers and their composites in the high frequency region, we proposed a simple hollow approximation method for hollow shaped magnetic particles using the modified demagnetizing factors of Sato’s and Aharoni’s cylindrical approximation methods. The obtained demagnetizing factors of the hollow magnetic particle by the proposed simple hollow approximation were not distinguished from those of the Beleggia’s complicated analytical results. The effective permeability of the magnetic hollow fiber filled in composite was evaluated using the effective medium theory and self-consistent iteration method using the simple hollow approximation. As the hollow ratio increased, the resonance frequency of the permeability shifted to a higher frequency region for the hollow fiber composite as well as for the single hollow fiber. The results of the calculated permeability using the proposed simple hollow approximation were in good agreement with Beleggia’s complicated analytical results.
Magnetostochastic resonance under colored noise condition
Authors: Trapanese Marco
Published: March 2012

Stochastic resonance (SR) is an amplification of the system output in correspondence of well-defined finite values of the noise strength that is injected into the system [Gammaitoni et al., Rev. Mod. Phys. 70, 223 (1998), Grigorenko et al., IEEE Trans. Magn. 31, 2491 (1995), Mantegna et al., J. Appl. Phys. 97, 10E519 (2005)]. In order to clarify the influence of a colored noise, in this paper magnetostochastic resonance (MSR) in magnetic systems described by the dynamic Preisach model is numerically investigated in the presence of colored noise. In this paper it is shown that: a) noise spectrum affects MSR; b) white noise, 1/f and 1/f2 noise induce in magnetic systems described by the dynamic Preisach model MSR; c) the maximum level of signal-to-noise (SNR) is obtained by using white noise but 1/f noise presents a range where SNR value is higher than the case of white noise; d) maximum signal amplification is obtained for white noise.
Magnetic behavior of Ni and Co doped CuMn2O4 spinels
Authors: McCloy John S. , Leslie Clifford , Kaspar Tiffany , Jiang Weilin , Bordia Rajendra K.
Published: March 2012

Mn1.68Co0.24Ni0.48Cu0.6O4 was produced via slip casting and sintering of spray-pyrolysis produced powders. The magnetic properties of this composition were measured for the first time, as a function of the processing temperature (900 °C or 1000 °C sintering), in order to study the effects of Cu and Mn valence and site preference. Quantitative x-ray photoelectron spectroscopy showed that Cu+ site occupancy changed from tetrahedral to a mix of tetrahedral and octahedral with increasing sintering temperature. X-ray diffraction demonstrated that the materials had a cubic spinel structure devoid of tetragonal Jahn-Teller distortion. ac magnetic susceptibility indicated ferrimagnetic behavior below ∼109 K and spin glass behavior below ∼66 to 74 K, depending on the measurement frequency. ac susceptibility freezing temperatures were modeled with the Vogel-Fulcher law and showed intermediate characteristics, between those of canonical spin glasses and cluster glasses.
A dual-channel flux-switching permanent magnet motor for hybrid electric vehicles
Authors: Hua Wei , Wu Zhongze , Cheng Ming , Wang Baoan , Zhang Jianzhong , Zhou Shigui
Published: March 2012

The flux-switching permanent magnet (FSPM) motor is a relatively novel brushless machine having both magnets and concentrated windings in the stator, which exhibits inherently sinusoidal PM flux-linkage, back-EMF waveforms, and high torque capability. However, in the application of hybrid electric vehicles, it is essential to prevent magnets and armature windings moving in radial direction due to the possible vibration during operation, and to ensure fault-tolerant capability. Hence, in this paper based on an original FSPM motor, a dual-channel FSPM (DC-FSPM) motor with modified structure to fix both armature windings and magnets and improved reliability is proposed for a practical 10 kW integral starter/generator (ISG) in hybrid electric vehicles. The influences of different solutions and the end-effect on the static characteristics, are evaluated based on the 2D and 3D finite element analysis, respectively. Finally, both the predicted and experimental results, compared with a prototype DC-FSPM motor and an interior PM motor used in Honda Civic, confirm that the more sinusoidal back-EMF waveform and lower torque ripple can be achieved in the DC-FSPM motor, whereas the torque is smaller under the same coil current.
Tunable energy bands and spin filtering in two-dimensional superlattices with spin-orbit interaction
Authors: Zhang R. L. , Li J. , Qi D. X. , Hu Qing , Peng R. W. , Huang R. S. , Wang Mu
Published: March 2012

We theoretically investigate the electronic energy bands and spin filtering tuned by Rashba spin-orbit coupling (SOC) and magnetic field in two-dimensional superlattices (2DSLs), where the square rods of quantum barriers, matrix, and wells are imposed periodically. It is shown that electronic energy spectra form a band structure and the energy levels are split up by the Rashba SOC. Correspondingly, the electrical conductance presents a “band-gap” structure against the electron energy. With manipulating the strength of SOC, the conductance in the “band” is enhanced for the spin-up electrons, while it is reduced for the spin-down electrons. Interestingly, by introducing a magnetic modulation, conductance curves for spin-up and spin-down electrons are translated in the different directions. As a result, high spin polarization is observed, and fully spin-polarized conductance is achieved in this 2DSL. Furthermore, the electronic wavefunctions have been obtained, which presents a clear picture of spin filtering. Our investigations achieve potential applications in spin quantum devices and spin filters.
Metallic state induced in Eu2Ru2O7 by hole creation and orbital overlap in the t2g bands
Authors: Muñoz-Perez S. , Cobas R. , Cadogan J. M. , Albino Aguiar J. , Bonville P. , Puig T. , Obradors X.
Published: March 2012

Two different series of ruthenium pyrochlores with the compositions Eu2−xCaxRu2O7 (0 ≤ x ≤ 0.6) and Eu2Ru2−xRexO7 (0 ≤ x ≤ 0.4) were prepared via solid state reaction, and their transport and magnetic properties were investigated. In both systems, the resistivity is shifted from 106 Ω cm to 10−3 Ω cm at low temperatures with increasing doping. The series correspond to two different approaches for inducing a metal–insulator transition in the Eu2Ru2O7 parent compound: (i) the substitution of Eu3+ by Ca2+, resulting in hole creation within the Ru t2g bands, and (ii) the partial substitution of Ru4+ (4d4) by Re4+ (5d3), leading to hole creation and an increase in the orbital overlap. Increasing the Ca or Re concentration suppresses the anomalies observed for Eu2Ru2O7 in dc magnetic susceptibility under zero-field-cooled and field-cooled conditions at 118 K and 23 K. In addition, a small negative magnetoresistance was obtained at low temperatures for doped samples with 2% Ca and Re.
Planar and non-planar dust ion-acoustic solitary waves in a quantum dusty electronegative plasma
Authors: Tasnim S. , Islam S. , Mamun A. A.
Published: March 2012

A theoretical investigation has been made on nonlinear propagation of planar and non-planar solitary waves in a quantum dusty electronegative plasma, whose constituents are quantum electrons, positive ions, negative ions, and arbitrarily charged stationary dust. The reductive perturbation method has been used to derive the Korteweg-de Vries and modified Korteweg-de Vries equations for studying the basic features of solitary waves, which are associated with both positive and negative ion dynamics. The effects of quantum parameter (H), positive and negative ion mass ratio (μin), as well as dust and positive ion number densities (β) on the basic features (polarity, height, and width) of planar solitary waves have been studied. It has been also found that the properties of dust ion-acoustic solitary waves in non-planar cylindrical or spherical geometry differ from those in planar one-dimensional geometry. The implications of our results in space (viz., interstellar compact objects like neutron stars) and laboratory experiments (e.g., intense laser solid density plasma experiments) have been briefly discussed.
A statistical model of write-errors in bit patterned media
Authors: Kalezhi Josephat , Greaves Simon J. , Kanai Yasushi , Schabes Manfred E. , Grobis Michael , Miles Jim J.
Published: March 2012

In bit patterned media (BPM), a magnetic data storage medium is patterned into nanoscale magnetic islands each representing one binary digit (bit). The recording performance of BPM depends upon the variability of island position, geometry, and magnetic characteristics. To understand the impact of the distributions of these parameters on the performance of BPM a detailed statistical model of write-errors has been developed. The islands can either be single layer or two-layer exchange coupled composite (ECC) structures. The modeling of ECC islands was made possible by the development of a 2-spin model to calculate switching field, coercivity, and energy barrier as a function of applied field which enables medium design to be optimized for a non-uniform write head field. The statistical model predicts coercivities and error rates in good agreement with a micromagnetic model but at significantly lower implementation and computational cost and shows good agreement with experimental data from drag-test experiments at 500 Gbit/in2. The model enables the position tolerance of the write head to be determined from the magnetic characteristics of the write head and the storage medium and it is therefore a valuable system design tool.
On the dynamics of vortex modes within magnetic islands
Authors: Hornsby W. A. , Peeters A. G. , Siccinio M. , Poli E.
Published: March 2012

Recent work investigating the interaction of magnetic islands with micro-turbulence has uncovered the striking observation of large scale vortex modes forming within the island structure [W. A. Hornsby et al., Phys. Plasmas 17, 092301 (2010)]. These electrostatic vortices are found to be the size of the island and are oscillatory. It is this oscillatory behaviour and the presence of turbulence that leads us to believe that the dynamics are related to the geodesic acoustic mode (GAM), and it is this link that is investigated in this paper. Here, we derive an equation for the GAM in the MHD limit, in the presence of a magnetic island modified three-dimensional axisymmetric geometry. The eigenvalues and eigenfunctions are calculated numerically and then utilised to analyse the dynamics of oscillatory large-scale electrostatic potential structures seen in both linear and non-linear gyro-kinetic simulations.
Role of mechanical loads in inducing in-cycle tensile stress in thermally grown oxide
Authors: Diaz Rene , Jansz Melan , Mossaddad Mitra , Raghavan Seetha , Okasinski John , Almer Jonathan , Pelaez-Perez Hugo , Imbrie Peter
Published: March 2012

Experimental in situ synchrotron x-ray diffraction results tracking the strain behavior of the various layers during a cycle, under thermo-mechanical conditions are presented in this work. The quantitative strain measurements here show that the thermally grown oxide briefly experiences in-plane tensile stress (σ22=+36.4 MPa) with increased mechanical loading during ramp-up in the thermal cycle. These findings are the first in situ experimental observations of these strains under thermo-mechanical conditions, envisaged to serve as a catalyst for crack initiation. The depth resolved measurements of strain taken during applied thermal and mechanical load in this work are a significant step towards achieving realistic testing conditions.
On the pressure calculation for polarizable models in computer simulation
Authors: Kiss Péter T. , Baranyai András
Published: March 2012

We present a short overview of pressure calculation in molecular dynamics or Monte Carlo simulations. The emphasis is given to polarizable models in order to resolve the controversy caused by the paper of M. J. Louwerse and E. J. Baerends [Chem. Phys. Lett. 421, 138 (2006)10.1016/j.cplett.2006.01.087] about pressure calculation in systems with periodic boundaries. We systematically derive expressions for the pressure and show that despite the lack of explicit pairwise additivity, the pressure formula for polarizable models is identical with that of nonpolarizable ones. However, a strict condition for using this formula is that the induced dipole should be in perfect mechanical equilibrium prior to pressure calculation. The perfect convergence of induced dipoles ensures conservation of energy as well. We demonstrate using more cumbersome but exact methods that the derived expressions for the polarizable model of water provide correct numerical results. We also show that the inaccuracy caused by imperfect convergence of the induced dipoles correlates with the inaccuracy of the calculated pressure.
Online and offline experimental techniques for polycyclic aromatic hydrocarbons recovery and measurement
Authors: Comandini A. , Malewicki T. , Brezinsky K.
Published: March 2012

The implementation of techniques aimed at improving engine performance and reducing particulate matter (PM) pollutant emissions is strongly influenced by the limited understanding of the polycyclic aromatic hydrocarbons (PAH) formation chemistry, in combustion devices, that produces the PM emissions. New experimental results which examine the formation of multi-ring compounds are required. The present investigation focuses on two techniques for such an experimental examination by recovery of PAH compounds from a typical combustion oriented experimental apparatus. The online technique discussed constitutes an optimal solution but not always feasible approach. Nevertheless, a detailed description of a new online sampling system is provided which can serve as reference for future applications to different experimental set-ups. In comparison, an offline technique, which is sometimes more experimentally feasible but not necessarily optimal, has been studied in detail for the recovery of a variety of compounds with different properties, including naphthalene, biphenyl, and iodobenzene. The recovery results from both techniques were excellent with an error in the total carbon balance of around 10% for the online technique and an uncertainty in the measurement of the single species of around 7% for the offline technique. Although both techniques proved to be suitable for measurement of large PAH compounds, the online technique represents the optimal solution in view of the simplicity of the corresponding experimental procedure. On the other hand, the offline technique represents a valuable solution in those cases where the online technique cannot be implemented.
Ferroelectric domain structures of 0.4-μm-thick Pb(Zr,Ti)O3 films prepared by polyvinylpyrrolidone-assisted Sol-Gel method
Authors: Yamano Akihiro , Takata Keiji , Kozuka Hiromitsu
Published: March 2012

Strain imaging of piezoelectric material enables us to observe piezo/ferroelectric properties with high resolution. We observed single-step-deposited 0.4-μm-thick Pb(Zr0.53Ti0.47)O3 (PZT). The PZT film had the small granular grains in size with around 40 nm, while the rosettes were around several micrometers in diameter. Observed domain structures were only determined by the rosette structures formed by nucleation of PZT. The grains were not columnar but granular, and so there are many grains in thickness direction but they were (001)-oriented. Therefore, polarization was aligned normal to the surface, and the structure to determine domain boundaries is neither grain boundaries nor crystalline axes but rosette boundaries. Relatively thick films provided stable polarization. The domain structures are flexible and well controllable by external electric fields. The positive surface charges were generated in the PZT surface by negative tip voltages. The presented images suggest that the positive surface charges coupled with spontaneous polarizations were rich at the circumferences of the rosettes. The positive surface charges generated negative charges on the tip, and the negative charges were deposited on the sample surface from the scanned tip.
Boundary layer turbulence in transitional and developed states
Authors: Park George Ilhwan , Wallace James M. , Wu Xiaohua , Moin Parviz
Published: March 2012

Using the recent direct numerical simulations by Wu and Moin [“Transitional and turbulent boundary layer with heat transfer,” Phys. Fluids 22, 85 (2010)] of a flat-plate boundary layer with a passively heated wall, statistical properties of the turbulence in transition at Reθ ≈ 300, from individual turbulent spots, and at Reθ ≈ 500, where the spots merge (distributions of the mean velocity, Reynolds stresses, kinetic energy production, and dissipation rates, enstrophy and its components) have been compared to these statistical properties for the developed boundary layer turbulence at Reθ = 1840. When the distributions in the transitional regions are conditionally averaged so as to exclude locations and times when the flow is not turbulent, they closely resemble the distributions in the developed turbulent state at the higher Reynolds number, especially in the buffer layer. Skin friction coefficients, determined in this conditional manner at the two Reynolds numbers in the transitional flow are, of course, much larger than when their values are obtained by including both turbulent and non-turbulent information there, and the conditional averaged values are consistent with the 1/7th power law approximation. An octant analysis based on the combinations of signs of the velocity and temperature fluctuations, u, v, and θ shows that the momentum and heat fluxes are predominantly of the mean gradient type in both the transitional and developed regions. The fluxes appear to be closely associated with vortices that transport momentum and heat toward and away from the wall in both regions of the flow. The results suggest that there may be little fundamental difference between the nonlinear processes involved in the formation of turbulent spots that appear in transition and those that sustain the turbulence when it is developed. They also support the view that the transport processes and the vortical structures that drive them in developed and transitional boundary layer turbulence are, in many dynamically important respects, similar.