bluuebunny/crossref_metadata_2025 huggingface dataset:
Towards operational payments for water ecosystem services in Tanzania: a case study from the Uluguru Mountains
Authors: Lopa Dosteus , Mwanyoka Iddi , Jambiya George , Massoud Thabit , Harrison Paul , Ellis-Jones Mark , Blomley Tom , Leimona Beria , van Noordwijk Meine , Burgess Neil D.
Published: February 2012

Sustaining the regular flow of water from mountain forests is important for downstream stakeholders in seasonally dry tropical countries, and a watershed payment for ecosystem services (PES) scheme that links rural ecosystem service providers to urban water users through economic transfers may help to maintain water supply and forest habitat. A CARE/WWF project in the Uluguru Mountains of Tanzania has established a pilot watershed PES scheme. We trace the development of this scheme and outline its initial impacts. Memoranda of Understanding between companies in Dar es Salaam (the downstream water users) and farmers in the mountains provide the framework to deliver tangible financial benefits to local people, help change patterns of land use and potentially improve water quality. A number of lessons learned from this project are relevant for similar schemes elsewhere in the region. Overcoming the various challenges is essential for expanding the current pilot project to a scale where it delivers measurable changes in water quality for downstream users.
AITIA, ASTRONOMY AND THE TIMING OF THE ARRHĒPHORIA
Authors: Boutsikas Efrosyni , Hannah Robert
Published: February 2012

This paper deals with the cult and myths of the daughters of the mythical king of Athens, Erechtheus, who lived on the Acropolis. The myth, preserved in Euripides’ tragedyErechtheus, establishes the deceased daughters as goddesses who are owed cult by the Athenians. It further equates them with the Hyades, a prominent star cluster in the constellation of Taurus, which they form after their deaths. We examine here the possibility that this myth not only narrates the placement of the girls after their death in the sky in the form of the Hyades, but also may have bound the constellation to certain festivals held on the Acropolis, which through their aetiological myths were connected to the daughters of Erechtheus and in which the participation of young girls (arrhēphoroi) was important. To explicate this cult, we explore its context on the Acropolis as fully as possible, through the visual arts, the literary myth, the festival calendar, and the natural landscape and night sky, so as to determine whether the movement of the Hyades was indeed visible from the Acropolis during the time when the young maiden cult rites were performed on the hill. This study investigates for the first time the role of the night sky and astronomical observations in the performance of the nocturnal festival of the Arrhēphoria.
‘I often worry about the older person being in that system’: exploring the key influences on the provision of dignified care for older people in acute hospitals
Authors: CALNAN M. , TADD W. , CALNAN S. , HILLMAN A. , READ S. , BAYER A.
Published: February 2012

Older age is one stage of the lifecourse where dignity maybe threatened due to the vulnerability created by increased incapacity, frailty and cognitive decline in combination with a lack of social and economic resources. Evidence suggests that it is in contact with health and welfare services where dignity is most threatened. This study explored the experiences of older people in acute National Health Service (NHS) Trusts in relation to dignified care and the organisational, occupational and cultural factors that affect it. These objectives were examined through an ethnography of four acute hospital Trusts in England and Wales, which involved interviews with older people (65+) recently discharged from hospital, their relatives/carers, and Trust managers, practitioners and other staff, complemented by evidence from non-participant observation. The picture which emerged was of a lack of consistency in the provision of dignified care which appears to be explained by the dominance of priorities of the system and organisation tied together with the interests of ward staff and clinicians. The emphasis on clinical specialism meant that staff often lacked the knowledge and skills to care for older patients whose acute illness is often compounded by physical and mental co-morbidities. The physical environment of acute wards was often poorly designed, confusing and inaccessible, and might be seen as ‘not fit for purpose’ to treat their main users, those over 65 years, with dignity. Informants generally recognised this but concluded that it was the older person who was in the ‘wrong place’, and assumed that there must be a better place for ‘them’. Thus, the present system in acute hospitals points to an inbuilt discrimination against the provision of high-quality care for older people. There needs to be a change in the culture of acute medicine so that it is inclusive of older people who have chronic co-morbidities and confusionas well asacute clinical needs.
Epidemiological concordance of Japanese encephalitis virus infection among mosquito vectors, amplifying hosts and humans in India
Authors: BORAH J. , DUTTA P. , KHAN S. A. , MAHANTA J.
Published: February 2012

A temporal relationship of Japanese encephalitis virus (JEV) transmission in pigs, mosquitoes and humans revealed that sentinel pig seroconversions were significantly associated with human cases 4 weeks before (P = 0·04) their occurrence, highly correlated during the same time and 2 weeks before case occurrence (P < 0·001), and remained significantly correlated up to 2 weeks after human case occurrence (P < 0·01). JEV was detected in the same month in pigs and mosquitoes, and peaks of pig seroconversion were preceded by 1–2 months of peaks of infection in vectors. Kaplan–Meier analysis indicated that detection of JEV-positive mosquitoes was significantly associated with the median time to occurrence of seroconversion in pigs (P < 0·05). This study will not only help in predicting JEV activity but also accelerate timely vector control measures and vaccination programmes for pigs and humans to reduce the Japanese encephalitis risk in endemic areas.
Continence aids in the management of urinary incontinence – CORRIGENDUM
Authors: Browning J. , Zaheer Z. , Orzechowska A. , Mistri A.
Published: February 2012

The legend to Figure 13 on page 11 of the above paper (Browning et al., 2012) was incomplete. The full legend is as follows:

Figure 13. Examples of washable incontinence underwear and disposable products (reproduced with permission from P&S Healthcare Ltd and SCA (TENA) Hygiene Products)
Reduced deforestation and the carbon market: the role of market regulations and future commitments
Authors: Anger Niels , Dixon Alistair , Livengood Erich
Published: February 2012

Reducing emissions from deforestation and degradation (REDD) has been proposed as an economic and extensive source of emission abatement to supplement other long-term climate policies. However, critics suggest an excess supply of REDD credits may disrupt emerging carbon markets and raise north–south equity concerns. In this context, we investigate the economic implications of REDD regulations and future emissions reduction commitments. Numerical model simulations show that unrestricted exchange of REDD units reduces the international carbon price by half and cuts compliance costs by roughly one-third. Developed nations’ requirements for policy supplementarity, which restrict demand for REDD credits, reduce such price impacts but go at the expense of both economic efficiency and benefits to rainforest areas. Instead, unlimited REDD access facilitates climate policy targets to be tightened by almost a quarter at constant compliance cost, tripling the environmental ambition of the Kyoto Protocol and providing considerable wealth transfers to developing countries.
What is an adequate standard of living during Retirement?
Authors: BINSWANGER JOHANNES , SCHUNK DANIEL
Published: February 2012

Many economists and policy-makers argue that households do not save enough to maintain an adequate standard of living during retirement. However, there is no consensus on the answer to the underlying question about what this standard should be, despite the fact that it is crucial for the design of saving incentives and pension systems. We address this question with a randomized survey design, individually tailored to each respondent's financial situation, and conducted both in the U.S. and The Netherlands. We find that adequate levels of retirement spending exceed 80% of working life spending for a majority of respondents. Minimum acceptable income replacement rates range from 95 to 45% across income quintiles in the U.S., and from 75 to 60% across income quintiles in The Netherlands. The smaller range in The Netherlands may in part reflect the much tighter income distribution there.
Factors in narratives to questions in the short-term life review interviews of terminally ill cancer patients and utility of the questions
Authors: Ando Michiyo , Morita Tatsuya , Akechi Tatsuo , Takashi Kouchi
Published: February 2012

Objective:

Although the Short-Term Life Review elevated the spiritual well-being of terminally ill cancer patients in our previous study, we have not examined what patients reviewed for each question item of it. We examined factors in narratives to questions in the Short-Term Life Review interviews of terminally ill cancer patients and utility of the questions.

Method:

Thirty-four terminally ill cancer patients received the Short-Term Life Review interview in which there were two sessions. In the first session patients reviewed their lives, and an interviewer made a simple album of the patient based on patients' narrative. After 1 week, there was a second session. Qualitative analysis was conducted on patients' answers to each question using computational word mining, and factors were identified.

Results:

Twenty patients' narratives were analyzed. “Human relationships” was identified under “important things in life.” “Pleasant memories” were associated with “impressive memories.” “Illness” and “marriage and divorce” were related to “turning points in the life.” “Raising children and education” and “company or work” were identified as “roles in life.” “Achievements at work” were identified with “pride.” “Message to my children” was identified with “what I want to say to my family.” “To live sincerely” and “consideration for others” were identified as “advice for the next generation.” Patients reviewed few for topics such as “pride,” “what I want to say to my family,” “advice for the next generation,” and “summing up my life.”

Significance of results:

Factors such as human relationships, raising children, and education as a role and source of pride, and concerns about children's future, were associated with elevating spiritual well-being. Question to which that patients easily answered were selected.
‘Destiny seems to point me to that country’: early nineteenth-century African American migration, emigration, and expansion
Authors: Everill Bronwen
Published: February 2012

Traditional American historiography has dismissed the Liberian settlement scheme as impractical, racist, and naïve. The movement of Americans to Liberia, and other territorial and extraterritorial destinations, however, reveals the ‘push’ and ‘pull’ factors that influenced movement in the African diaspora. The reaction of different African Americans to these factors influenced the political and social development of Liberia as well as the colony's image at home. Africans migrating within and beyond US borders participated in a broader movement of people and the development of settler ideology in the nineteenth century.
Globalizing St George: English associations in the Anglo-world to the 1930s
Authors: Bueltmann Tanja , MacRaild Donald M.
Published: February 2012

While English nationalism has recently become a subject of significant scholarly consideration, relatively little detailed research has been conducted on the emigrant and imperial contexts, or on the importance of Englishness within a global British identity. This article demonstrates how the importance of a global English identity can be illuminated through a close reading of ethnic associational culture. Examining organizations such as the St George's societies and the Sons of England, the article discusses the evolving character of English identity across North America, Africa, Southeast Asia and the Antipodes. Beginning in the eighteenth century, when English institutions echoed other ethnic organizations by providing sociability and charity to fellow nationals, the article goes on to map the growth of English associationalism within the context of mass migration. It then shows how nationalist imperialism – a broad-based English defence of empire against internal and external threats – gave these associations new meaning in the late nineteenth and early twentieth centuries. The article also explores how competitive ethnicity prompted English immigrants to form such societies and how both Irish Catholic hostility in America and Canada and Boer opposition in South Africa challenged the English to assert a more robust ethnic identity. English associationalism evinced coherence over time and space, and the article shows how the English tapped global reservoirs of strength to form ethnic associations that echoed their Irish and Scottish equivalents by undertaking the same sociable and mutual aspects, and lauded their ethnicity in similar fashion.
Constraints on 3‐D stress in the crust from support of mid‐ocean ridge topography
Authors: Luttrell Karen , Sandwell David
Published: February 2012

The direction of crustal stresses acting at mid‐ocean ridges is well characterized, but the magnitude of these stresses is poorly constrained. We present a method by which the absolute magnitude of these stresses may be constrained using seafloor topography and gravity. The topography is divided into a short‐wavelength portion, created by rifting, magmatism, and transform faulting, and a long‐wavelength portion associated with the cooling and subsidence of the oceanic lithosphere. The short‐wavelength surface and Moho topography are used to calculate the spatially varying 3‐D stress tensor in the crust by assuming that in creating this topography, the deviatoric stress reached the elastic‐plastic limiting stress; the Moho topography is constrained by short‐wavelength gravity variations. Under these assumptions, an incompressible elastic material gives the smallest plastic failure stress associated with this topography. This short‐wavelength topographic stress generally predicts the wrong style of earthquake focal mechanisms at ridges and transform faults. However, the addition of an in‐plane regional stress field is able to reconcile the combined crustal stress with both the ridge and transform focal mechanisms. By adjusting the magnitude of the regional stress, we determine a lower bound for in situ ridge‐perpendicular extension of 25–40 MPa along the slow spreading mid‐Atlantic ridge, 40–50 MPa along the ultra–slow spreading ridges in the western Indian Ocean, and 10–30 MPa along the fast spreading ridges of the southeastern Indian and Pacific Oceans. Furthermore, we constrain the magnitude of ridge‐parallel extension to be between 4 and 8 MPa in the Atlantic Ocean, between −1 and 7 MPa in the western Indian Ocean, and between −1 and 3 MPa in the southeastern Indian and Pacific Oceans. These observations suggest that a deep transform valley is an essential feature of the ridge‐transform spreading center.
A comparison of atmospheric dispersion model predictions with observations of SO2 and sulphate aerosol from volcanic eruptions
Authors: Heard Imogen P. C. , Manning Alistair J. , Haywood James M. , Witham Claire , Redington Alison , Jones Andy , Clarisse Lieven , Bourassa Adam
Published: February 2012

The UK Met Office's Numerical Atmospheric‐dispersion Modeling Environment (NAME) is used both operationally and for research investigations. It has previously been used to model volcanic ash at the London Volcanic Ash Advisory Centre (VAAC), including that from the eruptions in Iceland of Eyjafjallajökull in 2010 and Grímsvötn in 2011. In this paper, the ability of NAME to model the release and dispersion of volcanic SO2, the chemical processes leading to the production of sulphate aerosol, and the subsequent dispersion of sulphate aerosol, has been investigated. Sensitivity tests were carried out to investigate the suitability of the NAME chemistry scheme for use in both the troposphere and the stratosphere. The eruptions of Sarychev in 2009, Kasatochi in 2008 and Eyjafjallajökull in 2010 were simulated and results for SO2 column density and sulphate aerosol optical depth (AOD) were compared with satellite retrievals. NAME results compare favorably with available observations in terms of both geographical distribution and magnitude for all three cases. The NAME modeled values of SO2 show a correlation of 0.8 with the corresponding observations for Sarychev. Ninety percent of modeled values of northern hemisphere averaged sulphate AOD are within a factor of 2 of those observed for Kasatochi and 71% are within a factor of 2 of those observed for Sarychev. Although significant uncertainties are present in both the model and observations, this work demonstrates that NAME's current chemistry scheme shows promise as a tool for modeling SO2 and sulphate from volcanoes.
Hillslope asymmetry maps reveal widespread, multi‐scale organization
Authors: Poulos Michael J. , Pierce Jennifer L. , Flores Alejandro N. , Benner Shawn G.
Published: February 2012

Hillslope asymmetry is the condition in which oppositely‐facing hillslopes within an area have differing average slope angles, and indicates aspect‐related variability in hillslope evolution. As such, the presence, orientation and magnitude of asymmetry may be a useful diagnostic for understanding process dominance. We present a new method for quantifying and mapping the spatial distribution of hillslope asymmetry across large areas. Resulting maps for the American Cordillera of the Western Hemisphere and the western United States reveal that hillslope asymmetry is widespread, with distinct trends at continental to drainage scales. Spatial patterns of asymmetry correlate with latitude along the American Cordillera, mountain‐range orientation for many ranges in the western United States, and elevation in the Idaho Batholith of the Northern Rocky Mountains. Spatial organization suggests that non‐stochastic, process‐driven controls cause these patterns. The hillslope asymmetry metric objectively captures previously‐documented extents and frequencies of valley asymmetry for the Gabilan Mesa of the central California Coast Range. Broad‐scale maps of hillslope asymmetry are of interest to a wide range of disciplines, as spatial patterns may reflect the influence of tectonics, atmospheric circulation, topoclimate, geomorphology, hydrology, soils and ecology on landscape evolution. These maps identify trends and regions of hillslope asymmetry, allow possible drivers to be spatially constrained, and facilitate the extrapolation of site‐specific results to broader regions.
INCF Lithuanian Workshop on Neuroscience and Information Technology
Authors: Saudargiene Aušra
Published: February 2012

The aim of this workshop was to give a current overview of neuroscience and informatics research in Lithuania, and to discuss the strategies for forming the Lithuanian Neuroinformatics Node and becoming a member of INCF. The workshop was organized by Dr. Aušra Saudargiene (Department of Informatics, Vytautas Magnus University, Kaunas, and Faculty of Natural Sciences, Vilnius University, Lithuania) and INCF.The workshop was attended by 15 invited speakers, among them 4 guests and 11 Lithuanian neuroscientists, and over 20 participants. The workshop was organized into three main sessions: overview of the INCF activities including the Swedish and UK nodes of INCF; presentations on Neuroscience research carried out in Lithuania; discussion about the strategies for forming an INCF national node, and the benefits of having such a node in Lithuania (Appendix A: Program; Appendix B: Abstracts).
Fasting induces ketoacidosis and hypothermia in PDHK2/PDHK4-double-knockout mice
Authors: Jeoung Nam Ho , Rahimi Yasmeen , Wu Pengfei , Lee W. N. Paul , Harris Robert A.
Published: February 2012

The importance of PDHK (pyruvate dehydrogenase kinase) 2 and 4 in regulation of the PDH complex (pyruvate dehydrogenase complex) was assessed in single- and double-knockout mice. PDHK2 deficiency caused higher PDH complex activity and lower blood glucose levels in the fed, but not the fasted, state. PDHK4 deficiency caused similar effects, but only after fasting. Double deficiency intensified these effects in both the fed and fasted states. PDHK2 deficiency had no effect on glucose tolerance, PDHK4 deficiency produced only a modest effect, but double deficiency caused a marked improvement and also induced lower insulin levels and increased insulin sensitivity. In spite of these beneficial effects, the double-knockout mice were more sensitive than wild-type and single-knockout mice to long-term fasting, succumbing to hypoglycaemia, ketoacidosis and hypothermia. Stable isotope flux analysis indicated that hypoglycaemia was due to a reduced rate of gluconeogenesis and that slightly more glucose was converted into ketone bodies in the double-knockout mice. The findings establish that PDHK2 is more important in the fed state, PDHK4 is more important in the fasted state, and survival during long-term fasting depends upon regulation of the PDH complex by both PDHK2 and PDHK4.
Influences of Social and Style Variables on Adult Usage of African American English Features
Authors: Craig Holly K. , Grogger Jeffrey T.
Published: February 2012

Purpose

In this study, the authors examined the influences of selected social (gender, employment status, educational achievement level) and style variables (race of examiner, interview topic) on the production of African American English (AAE) by adults.

Method

Participants were 50 African American men and women, ages 20–30 years. The authors used Rapid and Anonymous Survey (RAS) methods to collect responses to questions on informal situational and formal message-oriented topics in a short interview with an unacquainted interlocutor.

Results

Results revealed strong systematic effects for academic achievement, but not gender or employment status. Most features were used less frequently by participants with higher educational levels, but sharp declines in the usage of 5 specific features distinguished the participants differing in educational achievement. Strong systematic style effects were found for the 2 types of questions, but not race of addressee. The features that were most commonly used across participants—copula absence, variable subject–verb agreement, and appositive pronouns—were also the features that showed the greatest style shifting.

Conclusions

The findings lay a foundation with mature speakers for rate-based and feature inventory methods recently shown to be informative for the study of child AAE and demonstrate the benefits of the RAS.
Preparation and magnetic properties of MnBi
Authors: Yang Y. B. , Chen X. G. , Wu R. , Wei J. Z. , Ma X. B. , Han J. Z. , Du H. L. , Liu S. Q. , Wang C. S. , Yang Y. C. , Zhang Y. , Yang J. B.
Published: February 2012

MnBi with low temperature phase was fabricated by melt-spinning and subsequently annealing. The influence of quenching speeds, compositions and annealing conditions on the formation of low temperature phase MnBi was systematically investigated. It was found the amorphous MnBi ribbons could transform into low temperature phase by heat treatment in a temperature range of 533–593 K. The coercivity of MnBi was greatly improved by porphyrization, and exhibited a positive temperature coefficient. The maximum energy product BHmax of the anisotropic bonded magnet is 7.1 MGOe (56 kJ/m3) and 4.0 MGOe (32 kJ/m3) at room temperature and 400 K.
Electrical manipulation of spin polarization and generation of giant spin current using multi terminal spin injectors
Authors: Nonoguchi S. , Nomura T. , Ando Y. , Kimura T.
Published: February 2012

Two advantages of the lateral spin valve using multi-terminal spin injections have been demonstrated. First, the effective spin polarization for the pure spin current can be controlled by the two anti-parallely aligned spin injectors. We show that the magnitude and the sign of the spin polarization are electrically manipulated by adjusting the current ratio between two injectors. Secondly, we show that the giant pure spin current can be generated by the nonlolcal spin injections from the quadruple spin injectors.
Jump-noise process-driven magnetization dynamics and random switching of magnetization
Authors: Liu Z. , Lee A. , Bertotti G. , Serpico C. , Mayergoyz I.
Published: February 2012

The Landau-Lifshitz equation driven by a jump-noise process is applied to the study of thermal magnetization switching for a very wide range of temperatures. It is demonstrated that at very low temperatures, magnetization switching deviates from the prediction of thermal activation theory and exhibits some features that have been traditionally attributed to the phenomena of “macroscopic tunneling” of magnetization.
Probability-current definition in presence of spin-orbit interaction
Authors: Bottegoni Federico , Drouhin Henri-Jean , Wegrowe Jean-Eric , Fishman Guy
Published: February 2012

A novel definition of the probability-current operator, based on a momentum power expansion of effective Hamiltonians, is presented. This operator can be applied in the presence of the Rashba term but also when the D’yakonov–Perel contribution is included. We exploit this formalism to find new boundary conditions and we apply our findings to the interface between two semi-infinite media, with on one side a free-electron-like material and on the other side a [110]-oriented GaAs barrier.
Anisotropy in collective precessional dynamics in arrays of Ni80Fe20 nanoelements
Authors: Rana B. , Kumar D. , Barman S. , Pal S. , Mandal R. , Fukuma Y. , Otani Y. , Sugimoto S. , Barman A.
Published: February 2012

The anisotropy in the collective precessional dynamics with the variation of azimuthal angle of the bias magnetic field is studied in arrays of permalloy (Ni80Fe20) nanoelements by an all-optical time-resolved Kerr microscope. When the nanoelements are very closely spaced (inter-element separation = 50 nm), a gradual transition from completely uniform collective regime to a completely non-collective regime is observed as the azimuthal angle varies from 0° to 45°. On the other hand, for inter-element separation of 100 nm, a non-uniform collective dynamics is observed at 0° and a non-collective dynamics is observed at 45° but no clear trend in the transition is observed.
Magneto-mechanical resonance of a single superparamagnetic microbead trapped by a magnetic domain wall
Authors: Rapoport Elizabeth , Beach Geoffrey S. D.
Published: February 2012

Magnetic domain walls in ferromagnetic tracks can be used to trap and transport superparamagnetic beads for lab-on-a-chip applications. Here it is shown that the magnetostatic binding between a domain wall and a superparamagnetic bead suspended in a host fluid leads to a distinct magneto-mechanical resonance under application of a sinusoidal driving field. The characteristic resonant frequency depends on the ratio of the magnetostatic binding force to the viscous drag on the bead. This resonance has been experimentally detected for a single trapped superparamagnetic bead using an optical detection technique.
Delayed switching applied to memristor neural networks
Authors: Wang Frank Z. , Helian Na , Wu Sining , Yang Xiao , Guo Yike , Lim Guan , Rashid Md Mamunur
Published: February 2012

Magnetic flux and electric charge are linked in a memristor. We reported recently that a memristor has a peculiar effect in which the switching takes place with a time delay because a memristor possesses a certain inertia. This effect was named the “delayed switching effect.” In this work, we elaborate on the importance of delayed switching in a brain-like computer using memristor neural networks. The effect is used to control the switching of a memristor synapse between two neurons that fire together (the Hebbian rule). A theoretical formula is found, and the design is verified by a simulation. We have also built an experimental setup consisting of electronic memristive synapses and electronic neurons.
Six-input lookup table circuit with 62% fewer transistors using nonvolatile logic-in-memory architecture with series/parallel-connected magnetic tunnel junctions
Authors: Suzuki D. , Natsui M. , Endoh T. , Ohno H. , Hanyu T.
Published: February 2012

A compact 6-input lookup table (LUT) circuit using nonvolatile logic-in-memory (LIM) architecture with series/parallel-connected magnetic tunnel junction (MTJ) devices is proposed for a standby-power-free field-programmable gate array. Series/parallel connections of MTJ devices make it possible not only to reduce the effect of resistance variation, but also to enhance the programmability of resistance values, which achieves a sufficient sensing margin even when process variation is serious in the recent nanometer-scaled VLSI. Moreover, the additional MTJ devices do not increase the effective chip area because the configuration circuit using MTJ devices is simplified and these devices are stacked over the CMOS plane. As a result, the transistor counts of the proposed circuit are reduced by 62% in comparison with those of a conventional nonvolatile LUT circuit where CMOS-only-based volatile static random access memory cell circuits are replaced by MTJ-based nonvolatile ones.
Effects of uniaxial strains on the magnetic properties and the electronic structures of Fe/graphene system: An ab initio study
Authors: Choi Heechae , Lee Eung-Kwan , Cho Sung Beom , Chung Yong-Chae
Published: February 2012

Using ab initio calculations, we investigated the changes of the magnetic moment and electronic structures of Fe adatoms on strained graphene sheets. By the uniaxial tensile strains in armchair and zig-zag directions on graphene sheets, the amounts of charge transfers from graphene 2pz orbital to Fe adatom 3d orbitals were linearly increased. The magnetic moments of Fe, however, show the tendency of linear decrements with the uniaxial tensile strains. The increased Fe magnetic moments by uniaxialy graphene compressions resulted from the shifting of spin-minority states of electrons while the decreased Fe magnetic moments were due to the reduction in the spin-majority states of 3dxy-orbitals of the Fe adatom.
Formations of magnetic vortices in a chain array of triangle Py dots and an isosceles triangle Py dot
Authors: Miyata M. , Kiseki K. , Yakata S. , Wada H. , Kimura T.
Published: February 2012

We have studied the magnetic domain structures in a magneto-statically-coupled chain array of the triangle dots and an isosceles triangle dot by means of magnetic force microscopy (MFM). Despite the strong magneto-static interaction in the chain array of the dots, each triangle dot takes a single vortex structure. The chirality of each dot is found to behave similarly to that for the isolated triangle dot. We also demonstrated that single-vortex and double-vortex structures with the desired chiralities can be stabilized in an isosceles triangle dot.
Manipulating femtosecond magnetization in ferromagnets and molecular magnets through laser chirp
Authors: Zhang G. P. , Lefkidis G. , Hübner W. , Bai Yihua
Published: February 2012

Laser chirp has found many applications in pulse shaping, high harmonic generation, and dynamical control of the vibrational excitation. Here, we show that the laser chirp can significantly affect the amount of the magnetic moment change in the laser-induced femtosecond magnetism. Under the same laser condition, an increase in the chirp from 0 to 0.04 rad/fs2 results in the magnetic moment change from 0.4% to 5% in ferromagnetic nickel. We find that the laser pulse duration has a direct effect on the effectiveness of the chirp. For a shorter pulse of duration 12 fs, the spin change with the chirp is small. We attribute this to a shorter interaction time and consequently a smaller instantaneous photon energy. We also investigate the effect of chirp on laser-induced local-spin-switching on molecular magnets consisting of two magnetic centers (Fe, Co, and Ni) bridged by Na atoms. We find that the effect of chirping differs depending on the original switching behavior of the atom. On Fe the chirp renders the process slightly less effective, on Ni it leads to a more dramatic loss of fidelity due to quantum interference, and for Co the effect lies in-between. Our study opens a new way to manipulate spin on femtosecond time scales.
Magnetic properties of ultrathin single crystal Fe3O4 film on InAs(100) by ferromagnetic resonance
Authors: Huang Z. C. , Hu X. F. , Xu Y. X. , Zhai Y. , Xu Y. B. , Wu J. , Zhai H. R.
Published: February 2012

The evolution of both in-plane and out-of-plane magnetic anisotropies has been studied on different thicknesses of Fe3O4/InAs(100) hybrid spintronic structures by ferromagnetic resonance. The uniaxial magnetic anisotropy with easy axis along InAs [011] direction and hard axis along [0-11] direction and the cubic magnetic anisotropy are determined by fitting the resonance field. The cubic magnetic anisotropy constant K1 is negative, as that of bulk magnetite, and its absolute value increases rapidly from 0.2 × 104 erg/cm3 to 10.8 × 104 erg/cm3 with increasing thickness of Fe3O4 film. When the thickness of Fe3O4 film is only several monolayers (tFe = 6 nm), a bulk-like cubic magneto-crystalline anisotropy is built up. The uniaxial anisotropy constant is much smaller than that in Fe3O4/GaAs film with the same thickness of Fe3O4 film, as expected from the less lattice mismatch at the interface.
Optical emission spectroscopy of the Linac4 and superconducting proton Linac plasma generators
Authors: Lettry J. , Fantz U. , Kronberger M. , Kalvas T. , Koivisto H. , Komppula J. , Mahner E. , Schmitzer C. , Sanchez J. , Scrivens R. , Midttun O. , Myllyperkiö P. , O’Neil M. , Pereira H. , Paoluzzi M. , Tarvainen O. , Wünderlich D.
Published: February 2012

CERN’s superconducting proton Linac (SPL) study investigates a 50 Hz high-energy, high-power Linac for H− ions. The SPL plasma generator is an evolution of the DESY ion source plasma generator currently operated at CERN's Linac4 test stand. The plasma generator is a step towards a particle source for the SPL, it is designed to handle 100 kW peak RF-power at a 6% duty factor. While the acquisition of an integrated hydrogen plasma optical spectrum is straightforward, the measurement of a time-resolved spectrum requires dedicated amplification schemes. The experimental setup for visible light based on photomultipliers and narrow bandwidth filters and the UV spectrometer setup are described. The Hα, Hβ, and Hγ Balmer line intensities, the Lyman band and alpha transition were measured. A parametric study of the optical emission from the Linac4 ion source and the SPL plasma generator as a function of RF-power and gas pressure is presented. The potential of optical emission spectrometry coupled to RF-power coupling measurements for on-line monitoring of short RF heated hydrogen plasma pulses is discussed.
Development of a compact filament-discharge multi-cusp H− ion source
Authors: Jia XianLu , Zhang TianJue , Zheng Xia , Qin JiuChang
Published: February 2012

A 14 MeV medical cyclotron with the external ion source has been designed and is being constructed at China Institute of Atomic Energy. The H− ion will be accelerated by this machine and the proton beam will be extracted by carbon strippers in dual opposite direction. The compact multi-cusp H− ion source has been developed for the cyclotron. The 79.5 mm long ion source is 48 mm in diameter, which is consisting of a special shape filament, ten columns of permanent magnets providing a multi-cusp field, and a three-electrode extraction system. So far, the 3 mA/25 keV H− beam with an emittance of 0.3 π mm mrad has been obtained from the ion source. The paper gives the design details and the beam test results. Further experimental study is under way and an extracted beam of 5 mA is expected.
Manufacturing of a superconducting magnet system for 28 GHz electron cyclotron resonance ion source at KBSI
Authors: Lee B. S. , Choi S. , Yoon J. H. , Park J. Y. , Won M. S.
Published: February 2012

A magnet system for a 28 GHz electron cyclotron resonance ion source is being developed by the Korea Basic Science Institute. The configuration of the magnet system consists of 3 solenoid coils for a mirror magnetic field and 6 racetrack coils for a hexapole magnetic field. They can generate axial magnetic fields of 3.6 T at the beam injection part and 2.2 T at the extraction part. A radial magnetic field of 2.1 T is achievable at the plasma chamber wall. A step type winding process was employed in fabricating the hexapole coil. The winding technique was confirmed through repeated cooling tests. Superconducting magnets and a cryostat system are currently being manufactured.
The impact of plasma-wall interaction on the gas mixing efficiency in electron cyclotron resonance ion source
Authors: Schachter L. , Stiebing K. E. , Dobrescu S.
Published: February 2012

It is generally accepted that different effects are necessary to explain the gas mixing method of increasing the output of highly charged ions from an ECRIS. The two most important effects are the mass effect and the dilution effect. Their relative weights have not been determined experimentally yet, but it is generally assumed that the mass effect is dominant in standard ECRIS installations with stainless steel plasma chambers. In order to gain more insight into the physics of the gas mixing effect and in particular on the relevance of the dilution process, we have carried out a study where we have investigated the role of the plasma-wall interaction on the gas mixing effect. In this contribution, we shall discuss Charge state distributions spectra, measured at the Frankfurt ECRIS using different working gases, pure argon, a mixture of argon and oxygen, and argon mixed with neon.
Micrometric periodic assembly of magnetotactic bacteria and magnetic nanoparticles using audio tapes
Authors: Godoy M. , Moreno A. J. , Jorge G. A. , Ferrari H. J. , Antonel P. S. , Mietta J. L. , Ruiz M. , Negri R. M. , Pettinari M. J. , Bekeris V.
Published: February 2012

We report micrometric periodic assembly of live and dead magnetotactic bacteria, Magnetospirillum magneticum AMB-1, which synthesize chains of magnetic nanoparticles inside their bodies, and of superparamagnetic Fe3O4 and ferromagnetic CoFe2O4 nanoparticles in aqueous suspensions using periodically magnetized audio tapes. The distribution of the stray magnetic field at the surface of the tapes was determined analytically and experimentally by magneto-optic imaging. Calculations showed that the magnetic field close to the tape surface was of the order of 100 mT, and the magnetic field gradient was larger than 1 T mm−1. Drops of aqueous solutions were deposited on the tapes, and bacteria and particles were trapped at locations where magnetic energy is minimized, as observed using conventional optical microscopy. Suspensions of M. magneticum AMB-1 treated with formaldehyde and kanamycin were studied, and patterns of trapped dead bacteria indicated that magnetic forces dominate over self-propelling forces in these experiments, in accordance with calculated values. The behavior of the different types of samples is discussed.
Invited Review Article: The uncertainty in the realization and dissemination of the SI second from a systems point of view
Authors: Parker Thomas E.
Published: February 2012

The uncertainty (accuracy) in the realization and dissemination of the SI second is determined by the characteristics of three major components: (1) primary frequency standards, (2) time scale flywheels that provide a continuously present frequency reference, and (3) frequency transfer systems. Currently these three systems contribute at approximately equal levels in the mid 10−16 range over 20 to 30 days of averaging time to the practical delivery of the SI second to the most demanding users. Any significant improvement in one system requires similar improvements in the other two systems in order for most users to see the full benefits.
Nucleation and growth kinetics during metal-induced layer exchange crystallization of Ge thin films at low temperatures
Authors: Hu Shu , McIntyre Paul C.
Published: February 2012

The kinetics of Al-catalyzed layer exchange crystallization of amorphous germanium (Ge) thin films at low temperatures is reported. Observation of Ge mass transport from an underlying amorphous Ge layer to the Al film surface through an interposed sub-nanometer GeOx interfacial layer allows independent measurement of the areal density and average area of crystalline Ge islands formed on the film surface. We show that bias-voltage stressing of the interfacial layer can be used to control the areal density of nucleated Ge islands. Based on experimental observations, the Johnson-Mehl-Avrami-Kolmogorov phase transformation theory is used to model nanoscale nucleation and growth of Ge islands in two dimensions. Ge island nucleation kinetics follows an exponentially decaying nucleation rate with time. Ge island growth kinetics switches from linear growth at a constant growth velocity to diffusion-limited growth as the growth front advances. The transition point between these two regimes depends on the Ge nucleation site density and the annealing temperature. Knowledge of the kinetics of low-temperature crystallization is important in achieving textured polycrystalline Ge thin films with large grains for applications in large-area electronics and solar energy conversion.
Non-Born-Oppenheimer electronic and nuclear densities for a Hooke-Calogero three-particle model: Non-uniqueness of density-derived molecular structure
Authors: Ludeña E. V. , Echevarría L. , Lopez X. , Ugalde J. M.
Published: February 2012

We consider the calculation of non-Born-Oppenheimer, nBO, one-particle densities for both electrons and nuclei. We show that the nBO one-particle densities evaluated in terms of translationally invariant coordinates are independent of the wavefunction describing the motion of center of mass of the whole system. We show that they depend, however, on an arbitrary reference point from which the positions of the vectors labeling the particles are determined. We examine the effect that this arbitrary choice has on the topology of the one-particle density by selecting the Hooke-Calogero model of a three-body system for which expressions for the one-particle densities can be readily obtained in analytic form. We extend this analysis to the one-particle densities obtained from full Coulomb interaction wavefunctions for three-body systems. We conclude, in view of the fact that there is a close link between the choice of the reference point and the topology of one-particle densities that the molecular structure inferred from the topology of these densities is not unique. We analyze the behavior of one-particle densities for the Hooke-Calogero Born-Oppenheimer, BO, wavefunction and show that topological transitions are also present in this case for a particular mass value of the light particles even though in the BO regime the nuclear masses are infinite. In this vein, we argue that the change in topology caused by variation of the mass ratio between light and heavy particles does not constitute a true indication in the nBO regime of the emergence of molecular structure.
Charge generation, charge transport, and residual charge in the electrospinning of polymers: A review of issues and complications
Authors: Collins George , Federici John , Imura Yuki , Catalani Luiz H.
Published: February 2012

Electrospinning has become a widely implemented technique for the generation of nonwoven mats that are useful in tissue engineering and filter applications. The overriding factor that has contributed to the popularity of this method is the ease with which fibers with submicron diameters can be produced. Fibers on that size scale are comparable to protein filaments that are observed in the extracellular matrix. The apparatus and procedures for conducting electrospinning experiments are ostensibly simple. While it is rarely reported in the literature on this topic, any experience with this method of fiber spinning reveals substantial ambiguities in how the process can be controlled to generate reproducible results. The simplicity of the procedure belies the complexity of the physical processes that determine the electrospinning process dynamics. In this article, three process domains and the physical domain of charge interaction are identified as important in electrospinning: (a) creation of charge carriers, (b) charge transport, (c) residual charge. The initial event that enables electrospinning is the generation of region of excess charge in the fluid that is to be electrospun. The electrostatic forces that develop on this region of charged fluid in the presence of a high potential result in the ejection of a fluid jet that solidifies into the resulting fiber. The transport of charge from the charge solution to the grounded collection device produces some of the current which is observed. That transport can occur by the fluid jet and through the atmosphere surrounding the electrospinning apparatus. Charges that are created in the fluid that are not dissipated remain in the solidified fiber as residual charges. The physics of each of these domains in the electrospinning process is summarized in terms of the current understanding, and possible sources of ambiguity in the implementation of this technique are indicated. Directions for future research to further articulate the behavior of the electrospinning process are suggested.
Dissolution of Sn in a SnPb solder bump under current stressing
Authors: Chiu Ying-Ta , Lin Kwang-Lung , Lai Yi-Shao
Published: February 2012

An in situ SEM/energy dispersive spectroscopy (EDS) analysis revealed that the dispersed Sn-rich phase of the 95Pb-5Sn solder in a 95Pb-5Sn/63Sn-37Pb composite solder bump dissolved under current stressing. The dissolution was not prominent until the current density reached a threshold value of between 3.3 × 104 and 4.2 × 104 A/cm2. Supersaturation over thermal solubility of Sn-in-Pb was detected with current stressing. A polarity dissolution model was proposed for the dissolution behavior of the Sn-rich phase under current stressing. The dissolution mechanism under current stressing was discussed in relation to electromigration and thermomigration behavior of SnPb solders.
Stress-strain dependence for soy-protein nanofiber mats
Authors: Khansari S. , Sinha-Ray S. , Yarin A. L. , Pourdeyhimi B.
Published: February 2012

Soy protein/nylon 6 monolithic and core-shell nanofibers were solution-blown and collected on a rotating drum as fiber mats. Tensile tests of rectangular strips of these mats revealed their stress-strain dependences. These dependences were linear at low strains which correspond to their elastic behavior. Then, a plastic-like nonlinearity sets in, which is followed by catastrophic rupture. Parameters such as Young’s modulus, yield stress, and specific strain energy were measured. The results were rationalized in the framework of the phenomenological elastic-plastic model, as well as a novel micromechanical model (the latter attributes plasticity to bond rapture between the individual overstressed fibers in the mat). Besides, the effects of stretching history, rate of stretching, and winding velocity of the collector drum on the strength-related parameters are studied. The results for soy protein/nylon 6 nanofiber mats are also compared to those for solution blown pure nylon 6 mats, which were produced and tested in the same way.