bluuebunny/crossref_metadata_2025 huggingface dataset:
The Normal 12-Lead Ecg
Authors: Spiers Chrissie
Published: February 2009

The 12-lead ECG provides information about the electrical activity in the heart viewed from 12 different directions and in two different planes. The standard 12 lead ECG consists of 3 bipolar leads (leads 1, 11 and 111) and 9 unipolar leads (aVR, aVL and aVF, V1-V6) giving information about the inferior wall, lateral left ventricular wall and anterior wall of the heart. It is an invaluable part of the preassessment of the patient prior to surgery and enables the surgeon and anaesthetist to risk assess the patient prior to anaesthetic and surgery.
Paediatric Fasting Times
Authors: Bratchell Joanne
Published: February 2009

The National Service Framework for Children [DoH, 2003] encourages the development of guidelines and the use of audit to ensure that the treatment and care offered to children is continually improving. Thus an audit was undertaken in a South London Day Surgery Unit to ascertain the fasting times of children undergoing dental treatment under general anaesthetic. A literature search identified that clear fluids can be safely ingested until two hours prior to general anaesthesia and the Trust guidelines were found to be congruent with current evidence.
Cost Versus Risk-Single-Use Versus Reuse
Authors: Gilmour Diane
Published: February 2009

In July 2001 nine year old Tony Clowes died after suffering brain damage during preparation for minor surgery, following a cycling accident, when an anaesthetic tubing became blocked with a foreign body. At the enquiry it emerged that the tubing had been used on other patients despite being labeled for single-use only. A year later police ruled out “foul play” and concluded that the tragic death was a “freak accident”. This was one of many such incidents being investigated by police at the time and resulted in national and nursing media frenzy concerning the reuse of single - use equipment. (Gallagher 2002; Kenny 2002; Mahoney 2001) The debate was further fuelled by the withdrawal of single - use tonsillectomy instruments as they posed a greater danger to patients than the theoretical risk of spreading variant Creutzfeldt - Jakob disease (CJD), the purpose for which they were originally introduced. (Gallagher 2002)
Irish Anaesthetic & Recovery Nurses Association - IARNA
Authors: Murphy Sheila
Published: February 2009

IARNA held its inaugural seminar in Cork on 16th November attracting over 250 anaesthetic and recovery nurses from all over Ireland. The excitement and enthusiasm was infectious - up to the formation of IARNA there had been little provision at all for specialist academic meetings within the sphere of anaesthetic and recovery nursing.
Reimbursement systems, organisational forms and patient selection: Evidence from day surgery in Norway
Authors: MARTINUSSEN PÅL E. , HAGEN TERJE P.
Published: February 2009

Cream skimming can be defined as the selective treatment of patients that demand few resources while providing high economic refunds. We test whether cream skimming occurs after the introduction of DRG-based activity-based financing (ABF) in Norway in 1997 and if the problem further increased after the 2002 organizational reform when hospitals were turned into trusts. The DRG-system offers the same economic reimbursement for patients classified within day-surgical DRGs irrespective of whether the patient receives same-day treatment or in-patient care over several days. This provides potential for cream skimming and allows us to investigate cream skimming within the actual diagnoses. Patient data from the period 1999-2005 is analyzed. Waiting times are used as indicators of patient selection and analyzed as a function of severity within each diagnosis, controlling for age and gender of the patient, as well as institutional and time-dependent variables. The analysis gives some evidence of cream skimming in the first period of ABF, in particular within the lighter orthopaedic diagnoses. However, cream skimming does not increase after the 2002 organizational reform but is stable, and for some DRGs even reduced. The study indicates that cream skimming may occur if reimbursement systems are not particularly sophisticated. Softening of budget constraints after the hospital reform of 2002 may explain why cream skimming does not increase after the reform. However, further investigation into this mechanism is needed.
Some pain, no gain: experiences with the no-claim rebate in the Dutch health care system
Authors: HOLLAND J. , VAN EXEL N.J.A. , SCHUT F.T. , BROUWER W.B.F.
Published: February 2009

To contain expenditures in an increasingly demand driven health care system, in 2005 a no-claim rebate was introduced in the Dutch health insurance system. Since demand-side cost sharing is a very controversial issue, the no-claim rebate was launched as a consumer friendly bonus system to reward prudent utilization of health services. Internationally, the introduction of a mandatory no-claim rebate in a social health insurance scheme is unprecedented. Consumers were entitled to an annual rebate of ₠ 255 if no claims were made. During the year, all health care expenses except for GP visits and maternity care were deducted from the rebate until the rebate became zero. In this article, we discuss the rationale of the no-claim rebate and the available evidence of its effect. Using a questionnaire in a convenience sample, we examined people’s knowledge, attitudes, and sensitivity to the incentive scheme. We find that only 4% of respondents stated that they would reduce consumption because of the no-claim rebate. Respondents also indicated that they were willing to accept a high loss of rebate in order to use a medical treatment. However, during the last month of the year many respondents seemed willing to postpone consumption until the next year in order to keep the rebate of the current year intact. A small majority of respondents considered the no-claim rebate to be unfair. Finally, we briefly discuss why in 2008 the no-claim rebate was replaced by a mandatory deductible.
Dynamic hierarchies: a control system paradigm for exposure therapy
Authors: Brady Alec , Raines David
Published: February 2009

Exposure therapy is a widely used and well-evidenced treatment for a variety of avoidance behaviours. This paper offers a modest proposal for an improvement in how it is carried out (‘dynamic hierarchies’). The theoretical and practical context is set out, including some thoughts on the role of appraisals and cognitive dissonance, and some advantages of the method are suggested.
On the possible formation of Alfvén wings at Mercury during encounters with coronal mass ejections
Authors: Sarantos Menelaos , Slavin James A.
Published: February 2009

The solar wind conditions near Mercury's perihelion, especially during Interplanetary Coronal Mass Ejection (ICME) events, will often be characterized by very low Alfvén Mach number (≤3). We suggest that the low Mach numbers and large north‐south magnetic fields during ICMEs will lead to the formation of “Alfvén wings” that will affect the configuration of the Hermean magnetosphere. It is shown that an electrical conductance threshold of about 5 S, comparable to the Alfvén conductance in the solar wind, is required for generation of Alfvén wings at Mercury. Assuming crustal conductances above this value it is demonstrated that currents in the Alfvén wings and closing across the planetary surface will produce significant perturbations (≥10 nT) of the magnetospheric magnetic field.
Regulated large‐scale annual shutdown of Amazonian isoprene emissions?
Authors: Barkley Michael P. , Palmer Paul I. , De Smedt Isabelle , Karl Thomas , Guenther Alex , Van Roozendael Michel
Published: February 2009

We perform Empirical Orthogonal Function (EOF) analysis on 12 years of global GOME and SCIAMACHY formaldehyde (HCHO) column observations to determine the most significant spatial and temporal HCHO variations. In most regions, we find that HCHO variability is predominantly driven by seasonal variations of biogenic emissions and biomass burning. However, unusually low HCHO columns are consistently observed over the Amazon rainforest during the transition from the wet‐to‐dry seasons. We use MODIS leaf area and enhanced vegetation indices, to show variations in vegetation are consistent with the observed decrease in HCHO during this period (correlations of 0.69 and 0.67, respectively). Based on this evidence, we suggest isoprene emitting vegetation experience widespread leaf flushing (new leaf growth) prior to the dry season, resulting in a large‐scale annual shutdown of Amazonian isoprene emissions.
Characteristics of large Martian dust devils using Mars Odyssey Thermal Emission Imaging System visual and infrared images
Authors: Towner M. C.
Published: February 2009

A search for Martian dust devils has been carried out, using Mars Odyssey Thermal Emission Imaging System (THEMIS) visible‐wavelength images. Simultaneous THEMIS thermal infrared wavelength images were then processed and analyzed to investigate the thermal properties of the dust devils observed; 3079 images were checked, concentrating on northern spring, summer, and autumn (LS from 0° to 270°, 20°S to 50°N). Mars Express High Resolution Stereo Camera, Mars Global Surveyor Mars Orbiter Camera, and other THEMIS visible images were used for comparison to potentially rule out any ambiguous geological features. Eight clear examples of dust devils have been found in five separate images, with a comparable number of unconfirmed possible devils. The rarity of dust devils observed is believed to result from a combination of the difficulty in identifying dust devils in medium resolution THEMIS data and the fact that the Mars Odyssey orbit flyover local time is later in the afternoon than would be optimum for dust devil searching. The temporal distribution of dust devil activity appears to be weighted more toward later afternoon, compared to Earth, but this may be a sampling effect due to size variation with time of sol, greater coverage later in the sol, or the small‐number statistics. The thermal infrared images indicate that the lofted dust in the column is cooler than the surrounding surface and must be equilibrating with the atmosphere in the dust devil. This energy transfer is estimated to be about 10% of the heat flux energy that is available to drive the systems. The ground shadowed by the dust column also appears colder than the surroundings, because of reduced solar illumination. From the visible‐wavelength images, the shadows of the dust columns were used to estimate the column opacity, which in turn gave estimates of the dust loadings, which ranged from 1.9 × 10−5 to 1.5 × 10−4 kg m−3, similar to lander‐based observations. No thermal or visible trails are associated with the dust devils, indicating that the surface equilibrates quickly after the devil has passed and that track counting as a dust devil survey technique must underestimate dust devil populations and consequently dust loading calculations, confirming previous work.
The soft tissue response to contaminated and cleaned titanium surfaces using CO2 laser, citric acid and hydrogen peroxide
Authors: Mouhyi Jaafar , Sennerby Lars , Van Reck Jack
Published: February 2009

The soft tissue response to clinically retrieved and decontaminated cover screws was evaluated in a rat model. The cover screws were cleaned by using citric acid, sterile water, hydrogen peroxide and CO2 laser alone or with a combination of these. In addition, decontaminated but not cleaned and unused cover screws were used as negative and positive controls, respectively. After cleaning the cover screws were implanted in the abdominal wall of the rat for 6 weeks. The thickness of the fibrous capsule and the number of macrophages within the capsule were measured by means of light microscopical morphometry. As compared to the negative control, CO2 laser on dry surface, CO2 laser+hydrogen peroxide and the positive control had statistically significant thinner fibrous capsules. As compared to the positive, only laser alone resulted in a similar tissue response. It is concluded that CO2 laser used alone or in combination with hydrogen peroxide may be used clinically for sufficient decontamination of titanium surfaces.
Survival of single crystal sapphire implants supporting mandibular overdentures
Authors: Berge Trond I. , Grønningsæter Arne G.
Published: February 2009

One hundred and sixteen sapphire (Bioceram®, Kyocera) implants were inserted in 30 patients between 1984 and 1991 to support mandibular overdentures. Survival analyses were made on the basis of clinical and radiographic follow‐up evaluation for 15 patients with 56 implants. For the 15 patients who were lost to follow‐up, 7 of whom were deceased, reviews of records and available radiographs determined outcome and observation time. The resulting Kaplan–Meier cumulative survival rate for the sapphire implants was 68.66%, mean survival time 11.44 years, 95% confidence interval 10.56–12.32 years. Uni‐ and multivariate analysis using the Cox Regression model, indicated an increased risk of implant failure in patients over 60 years at time of operation, and in patients who smoke. Limited experience in implant surgery were associated with increased implant failure rate. A qualitative analysis of survived implants showed a mean annual bone loss of 0.2 mm, moderate to excellent plaque control, and excellent to good subjective global assessment of the treatment. The long‐term results of the sapphire implant system used for mandibular overdenture support are inferior to other implants systems.
A 41‐year history of a mandibular subperiosteal implant
Authors: Schou Søren , Pallesen Lars , Hjørting‐Hansen Erik , Pedersen Carsten S. , Fibæk Bent
Published: February 2009

The subperiosteal implant was originally described in the 1940s. The inadequate long‐term results of subperiosteal implants are in contrast to the excellent results documented for endosseous osseointegrated oral implants. Consequently, subperiosteal implants and other soft‐tissue‐anchored implants should not be used presently. Furthermore, these implants are seldom seen today, because they generally were removed rather shortly after placement. The present report documents a full 41‐year history of a mandibular subperiosteal implant inserted in 1957 by focusing upon the consequences of not removing an implant in spite of continuous periods of complications during 4 decades. Implant exposure, inflammation, infection, and fistula formation occurred persistently. Total implant removal was refused by the patient in 1973. After 25 years without control, tremendous resorption of the mandible was observed in 1998. Consequently, the entire implant was then removed. Placement of osseointegrated oral implants was impossible without extensive autogenous bone grafting. The present report has demonstrated that regular control of patients with subperiosteal implants is mandatory. Furthermore, subperiosteal implants should definitely be removed, if continuous periods of complications occur.
Kinetic Profile of the Transcriptome Changes Induced in the Choroid Plexus by Peripheral Inflammation
Authors: Marques Fernanda , Sousa João C , Coppola Giovanni , Falcao Ana M , Rodrigues Ana João , Geschwind Daniel H , Sousa Nuno , Correia-Neves Margarida , Palha Joana A
Published: February 2009

The choroid plexus, being part of the blood-brain barriers and responsible for the production of cerebrospinal fluid, is ideally positioned to transmit signals into and out of the brain. This study, using microarray analysis, shows that the mouse choroid plexus displays an acute-phase response after an inflammatory stimulus induced in the periphery by lipopolysaccharide (LPS). Remarkably, the response is specific to a restricted number of genes (out of a total of 24,000 genes analyzed, 252 are up-regulated and 173 are down-regulated) and transient, as it returns to basal conditions within 72 h. The up-regulated genes cluster into families implicated in immune-mediated cascades and in extracellular matrix remodeling, whereas those down-regulated participate in maintenance of the barrier function. Importantly, several acute-phase proteins, whose blood concentrations rise in response to inflammation, may contribute to the effects observed in vivo after LPS injection, as suggested by the differential response of primary choroid plexus epithelial cell cultures to LPS alone or to serum collected from animals exposed to LPS. By modulating the composition of the cerebrospinal fluid, which will ultimately influence the brain parenchyma, the choroid plexus response to inflammation may be of relevance in brain homeostasis in health and disease.
Deep Hypothermia Markedly Activates the Small Ubiquitin-Like Modifier Conjugation Pathway; Implications for the Fate of Cells Exposed to Transient Deep Hypothermic Cardiopulmonary Bypass
Authors: Yang Wei , Ma Qing , Mackensen G Burkhard , Paschen Wulf
Published: February 2009

Various cardiovascular operations are performed during conditions of deep hypothermic circulatory arrest. Here we investigated the effects of deep hypothermia on the small ubiquitin-like modifier (SUMO) conjugation pathway using a clinically relevant animal model of deep hypothermic cardiopulmonary bypass (DHCPB). Deep hypothermic cardiopulmonary bypass induced a marked activation of the SUMO conjugation pathway and triggered a nuclear translocation of SUMO2/3-conjugated proteins. Furthermore, DHCBP significantly modified gene expression. Activation of the SUMO conjugation pathway is believed to protect neurons from damage caused by low blood flow. This pathway may, therefore, play a key role in defining the outcome of cells exposed to DHCPB.
Interleukin-1β Augments Angiogenic Responses of Murine Endothelial Progenitor Cells in Vitro
Authors: Rosell Anna , Arai Ken , Lok Josephine , He Tongrong , Guo Shuzhen , Navarro Miriam , Montaner Joan , Katusic Zvonimir S , Lo Eng H
Published: February 2009

Endothelial progenitor cells (EPCs) may provide novel opportunities for therapeutic angiogenesis after ischemic diseases. However, it is unclear how the angiogenic potential of EPCs might be affected by an inflammatory environment. We examine how the potent cytokine interleukin-1β (IL-1β) affects angiovasculogenic responses in EPCs in culture. Mononuclear cells isolated from mouse spleen were plated on fibronectin-coated wells and grown in EGM-2 MV media. Endothelial progenitor cells were phenotyped using multiple markers (UEA-Lectin, ac-LDL, CD133, CD34, vWillebrand Factor, Flk-1) and to identify the IL-1 Receptor-I. We quantified cell and colony counts and performed MTT (3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl-tetrazolium bromide) and Matrigel assays, in vitro, under control and IL-1β (10 ng/mL) conditions. Endothelial progenitor cells exposed to IL-1β increased in the number of cells and colonies compared with untreated cells, without any effect on cell metabolic integrity. Furthermore, IL-1β treatment augmented EPC angiogenic function, significantly increasing the number of vessel-like structures in the Matrigel assay. An early phosphorylation of ERK1/2 occurred after IL-1β stimulation, and this pathway was inhibited if IL-1 Receptor-I was blocked. Our results suggest that IL-1β is a potent stimulator of in vitro angiogenesis through ERK signaling in mouse EPCs. Further studies are warranted to assess how interactions between proinflammatory environments and EPC responses may be leveraged to enhance therapeutic angiogenesis.
Phase transformations and magnetic structure of nanocrystalline Fe–Pd and Co–Pt alloys studied by in situ neutron powder diffraction
Authors: Lyubina Julia , Gutfleisch Oliver , Isnard Olivier
Published: February 2009

The formation of the ordered L10 structure from the A1 phase in nanocrystalline Fe100−xPdx (x=50–60) and Co100−xPtx (x=45–55) alloys is followed by in situ neutron powder diffraction. The A1→L10 transformation starts at about 620 and 730K in Fe50Pd50 and Co50Pt50, respectively, and proceeds faster in the Fe–Pd alloys. In both Fe–Pd and Co–Pt, a deviation from the equiatomic composition leads to the deceleration of the ordering process. The magnetic moment of iron in the L10 FePd phase decreases with increasing Fe concentration from 3.3μB in Fe40Pd60 to 3.0μB in Fe50Pd50. In the Co–Pt alloys, the Co magnetic moment is found to be independent of the composition and degree of chemical order and is equal to 1.9μB.
Electronic continuum model for molecular dynamics simulations
Authors: Leontyev I. V. , Stuchebrukhov A. A.
Published: February 2009

A simple model for accounting for electronic polarization in molecular dynamics (MD) simulations is discussed. In this model, called molecular dynamics electronic continuum (MDEC), the electronic polarization is treated explicitly in terms of the electronic continuum (EC) approximation, while the nuclear dynamics is described with a fixed-charge force field. In such a force-field all atomic charges are scaled to reflect the screening effect by the electronic continuum. The MDEC model is rather similar but not equivalent to the standard nonpolarizable force-fields; the differences are discussed. Of our particular interest is the calculation of the electrostatic part of solvation energy using standard nonpolarizable MD simulations. In a low-dielectric environment, such as protein, the standard MD approach produces qualitatively wrong results. The difficulty is in mistreatment of the electronic polarizability. We show how the results can be much improved using the MDEC approach. We also show how the dielectric constant of the medium obtained in a MD simulation with nonpolarizable force-field is related to the static (total) dielectric constant, which includes both the nuclear and electronic relaxation effects. Using the MDEC model, we discuss recent calculations of dielectric constants of alcohols and alkanes, and show that the MDEC results are comparable with those obtained with the polarizable Drude oscillator model. The applicability of the method to calculations of dielectric properties of proteins is discussed.
Characteristic analysis of electrodynamic suspension device with permanent magnet Halbach array
Authors: Cho Han-Wook , Han Hyung-Seok , Bang Je-Sung , Sung Ho-Kyung , Kim Byung-Hyun
Published: February 2009

This article deals with the characteristic analysis of electrodynamic suspension (EDS) device with the permanent magnet (PM) Halbach array system. On the basis of transfer relation theorem with magnetic vector potential, the magnetic field quantities were obtained and then confirmed with the corresponding two-dimensional and three-dimensional finite element analysis result. In order to validate the characteristic analysis scheme for PM-EDS device, the dynamic performance was tested by using a high-speed rotary-type dynamic test facility with linear peripheral speed up to 250 km/h. A comparison is made between the analysis and the experimental results to demonstrate the design considerations of PM-EDS device for high-speed maglev.
Current-perpendicular-to-plane giant magnetoresistance of a spin valve using Co2MnSi Heusler alloy electrodes
Authors: Kodama K. , Furubayashi T. , Sukegawa H. , Nakatani T. M. , Inomata K. , Hono K.
Published: February 2009

We report the current-perpendicular-to-plane (CPP) giant magnetoresistance (GMR) of a spin valve with Co2MnSi (CMS) Heusler alloy ferromagnetic electrodes. A multilayer stack of Cr/Ag/Cr/CMS/Cu/CMS/Fe25Co75/Ir28Mn72/Ru was deposited on a MgO (001) single crystal substrate. The bottom CMS layer was epitaxially grown on the Cr/Ag/Cr buffer layers and was ordered to the L21 structure after annealing at 673 K. The upper CMS layer was found to grow epitaxially on the Cu spacer layer despite the large lattice mismatch between Cu and CMS. The highest MR ratios of 8.6% and 30.7% for CPP GMR were recorded at room temperature and 6 K, respectively. The high spin polarization of the epitaxial CMS layers is the most likely origin of the high MR ratio.
Accurate ab initio potential energy surface, dynamics, and thermochemistry of the F+CH4→HF+CH3 reaction
Authors: Czakó Gábor , Shepler Benjamin C. , Braams Bastiaan J. , Bowman Joel M.
Published: February 2009

An accurate full-dimensional global potential energy surface (PES) for the F+CH4→HF+CH3 reaction has been developed based on 19 384 UCCSD(T)/aug-cc-pVTZ quality ab initio energy points obtained by an efficient composite method employing explicit UCCSD(T)/aug-cc-pVDZ and UMP2/aug-cc-pVXZ [X=D,T] computations. The PES contains a first-order saddle point, (CH4- -F)SP, separating reactants from products, and also minima describing the van der Waals complexes, (CH4- - -F)vdW and (CH3- - -HF)vdW, in the entrance and exit channels, respectively. The structures of these stationary points, as well as those of the reactants and products have been computed and the corresponding energies have been determined using basis set extrapolation techniques considering (a) electron correlation beyond the CCSD(T) level, (b) effects of the scalar relativity and the spin-orbit couplings, (c) diagonal Born–Oppenheimer corrections (DBOC), and (d) zero-point vibrational energies and thermal correction to the enthalpy at 298 K. The resulting saddle point barrier and ground state vibrationally adiabatic barrier heights (VSP and VVAGS), dissociation energy of (CH3- - -HF)vdW (De and D0), and the reaction enthalpy (ΔHe°, ΔH0°, and ΔH298°) are (240±40 and 245±200 cm−1), (1070±10 and 460±50 cm−1), and (−10000±50, −11200±80, and −11000±80 cm−1), respectively. Variational vibrational calculations have been carried out for (CH3- - -HF)vdW in full (12) dimensions. Quasiclassical trajectory calculations of the reaction using the new PES are reported. The computed HF vibrational and rotational distributions are in excellent agreement with experiment.
Noninvasive detection of unevenly magnetized permanent magnet of a brushless dc motor by characterizing back electromotive force
Authors: Lee C. I. , Jang G. H.
Published: February 2009

Uneven magnetization of permanent magnets (PMs) is one of the major sources of unbalanced magnetic force and torque ripple, which excite a brushless dc (BLDC) motor. This paper investigates the frequency contents of the back electromotive force (BEMF) due to the unevenly magnetized PMs in a BLDC motor. The magnetic field of a BLDC motor is solved by using the finite element method, and the BEMF is calculated by differentiating the flux linkage with respect to time. The characteristics of BEMF are investigated by using the spectral analysis. Magnetic flux density of the ideally magnetized PMs has the harmonics of the pole-pair number, but unevenly magnetized PMs generate the additional harmonics. This research shows numerically and experimentally that the frequency components of the BEMF are determined by the least common multiple between the frequency contents of magnetic flux density from the PMs and the slot number per phase. It also shows that the magnetized status of the PMs of a BLDC can be noninvasively identified by monitoring the frequencies and the amplitudes of BEMF.
Spin torque based magnetic content addressable memory
Authors: Wang Weizhong , Jiang Zhenye
Published: February 2009

In this paper, we introduce novel spin torque magnetic content addressable memory (MCAM) architecture. Spin torque programming has demonstrated good repeatability and scalability. However, MCAM demands both magnets of magnetic tunneling junction (MTJ) to be programmable, which is incompatible with spin torque transfer. We propose a two-MTJ based MCAM cell architecture, where a single MCAM cell consists of two identical stacks. Each stack consists of (from bottom to top) synthetic antiferromagnetic (SAF) based bottom magnet, tunneling barrier, top magnet, nonmagnetic layer, and pinned magnetic layer. The bottom SAF magnets are programmed by switching field generated by cross bar currents, which is much lower than the switching field for top magnet. The top magnet is programmed by the spin torque transfer by the current from/to the pinned magnets. The top magnets are used to store comparands. The programming current flows from the pinned layer to the top magnet in one stack and from top magnet to the pinned layer in the other stack. Since the pinned layers in both stacks have the same magnetization orientation, the top magnets of two MTJ stacks are expected to store complimentary bit. The bottom magnets are used to store database bits. Inside each MCAM cell, two stacks are connected at MTJ top magnet layer. In reading operation, both MTJs are in the same states. Therefore, the series resistance represents the matching results. The feasibility study of the proposed MCAM cell architecture is demonstrated by using LLG and OMMFF micromagnetic simulation on the programming field windows.
Influence of thermal excitation on magnetization states and switching routes of magnetic multilayer rings
Authors: Lee J. H. , Hayward T. J. , Holmes S. N. , Hong B. , Llandro J. , Cooper K. , Anderson D. , Jones G. A. C. , Barnes C. H. W.
Published: February 2009

The low temperature magnetic switching behavior of micron scale NiFe/Cu/Co circular ring elements has been investigated using micromagnetic simulations and magnetoresistance (MR) measurements. The rings were patterned, so that two different contact configurations could be used to measure MR simultaneously. By comparing these measurements with the simulation results, the rings’ magnetization states and switching routes were determined at both 1.7 and 300 K. It was found that at 1.7 K the rings exhibited multiple switching routes and also showed more metastable states and broader transitions between states than was observed at 300 K. The rings’ behavior at low temperature is explained as the result of an increase in the strength of magnetocrystalline and magnetoelastic anisotropies combined with an absence of thermal excitation which would usually aid the nucleation and depinning of domain walls.
Magnetocaloric effects in the La(Fe,Si)13 intermetallics doped by different elements
Authors: Jia L. , Sun J. R. , Shen J. , Dong Q. Y. , Zou J. D. , Gao B. , Zhao T. Y. , Zhang H. W. , Hu F. X. , Shen B. G.
Published: February 2009

The magnetocaloric effects (MCEs) of LaFe13−xSix compounds doped by magnetic rare earths (R=Ce, Pr, and Nd) and transition metal (Co) are analyzed. It is found that varying the contents of R and Fe produces similar effects on the MCE, both of which cause a rapid decrease in ΔS with the increase in TC. The ΔS−TC relations thus obtained coincide with each other fairly well, which indicates the equivalence of substituting R for La and Fe for Si. In contrast, partially replacing Fe by Co leads to a slow decrease in ΔS with TC. It is therefore a promising approach to maintain a large ΔS up to high temperatures. As a comparison with these element-doping compounds, the MCEs of hydrides are also discussed. Although interstitial hydrogen can also keep up a large ΔS to high temperatures, the corresponding hydrides are unfortunately unstable above 150 °C. Based on these analyses, the potential refrigerants made of LaFe13−xSix are proposed to have as low as possible Si content (or high R content) and proper Co content simultaneously.
Interface-related damping in polycrystalline Ni81Fe19/Cu/Co93Zr7 trilayers
Authors: Zohar S. , Bailey W. E.
Published: February 2009

We have searched for a signature of nonlocal magnetization dynamics or magnetization dynamics driven by pure spin currents, in magnetically soft polycrystalline Ni81Fe19/Cu/Co93Zr7 trilayers using ferromagnetic resonance. An interface-related enhancement of damping is expected for each ferromagnetic layer when incorporated in a trilayer; the enhancement should be absent where layer resonances overlap. While size effects in Gilbert damping have been identified, we note that expectations specific to spin pumping are not confirmed.
Co nanostructure arrays in patterned polymeric template
Authors: Rosa W. O. , Jaafar M. , Asenjo A. , Vázquez M.
Published: February 2009

Nanostructured polymer (polymethyl methacrylate) has been fabricated replicating the hexagonal symmetry ordering of an anodized Al template. A magnetic material, in this case Co, is then sputtered onto the polymer surface giving rise to a nanostructured surface thin layer keeping the high ordering induced by the precursor template. The study of this magnetic nanostructure allows one to conclude the presence of intrinsic distribution of magnetic anisotropy and the identification of single or multidomain structures inside Co depending on the controlled periodicity of the nanostructured Al template.
The exchange biaslike effect in tetrahedral spinels Cu1−xZnxCr2O4(x=0.1,0.3)
Authors: Yan L. Q. , Ren W. , Shen J. , Sun Z. H. , Wang F. W.
Published: February 2009

Exchange biaslike phenomenon is observed in the Zn doped spinel polycrystalline CuCr2O4. The magnetic hysteresis loop shifts in both horizontal and vertical directions at 5 K after the samples are cooled down to 5 K in a magnetic field. The nature of this magnetic anisotropy arises from the freezing properties of the local anisotropy in the cluster glass system. The magnetic shifts along both directions can be observed directly under the principle that the spins of a cluster are frozen in random orientations upon zero field, and aligned to the field direction upon field cooling.
ac susceptibility studies of magnetic relaxation in nanoparticles of Ni dispersed in silica
Authors: Singh V. , Seehra M. S. , Bonevich J.
Published: February 2009

Temperature dependence of ac susceptibilities χ′ and χ″ are reported using frequencies fm=0.1, 1, 99, 499, and 997 Hz for nanoparticles of Ni dispersed in silica (Ni/SiO2:15/85) with the mean sizes D=3.8, 11.7, 15, and 21 nm (σ≃0.2 nm), as determined by transmission electron microscopy. The blocking temperatures TB, as determined by peaks in χ″ versus T data, are fit to the Vogel–Fulcher law based on the following equation: TB=To+Ta/ln(fo/fm). Using the attempt frequency fo=1.82×1010 Hz, Ta (K)=310 (21), 954(17), 1334(14), and 1405(47) are determined for D=3.8, 11.7, 15, and 21 nm, respectively, along with To (representing the interparticle interaction)=0, 0, 6.6(0.7), and 12.5(2.5) K respectively. The magnitudes of Ta=KaV/k yield the anisotropy constant Ka increasing with decreasing D (or volume V) due to contributions from surface anisotropy. The validity of the theoretical result χ″=C∂(χ′T)/∂T with C≃π/[2 ln(fo/2πfm)] is checked and the calculated values of fo are consistent with experimental value of fo=1.82×1010 Hz.
Infrared transparent carbon nanotube thin films
Authors: Hu Liangbing , Hecht David S. , Grüner George
Published: February 2009

We have measured the infrared properties of optically transparent and electrically conductive single walled carbon nanotube thin films. We found that nanotube films with sheet resistance values of 200 Ω/sq show outstanding transmittance in the infrared range up to at least 22 μm, with an average transmittance greater than 90% over this range. The infrared properties of various materials were compared and we found that transparent nanotube electrodes and transparent graphene electrodes outperform the others in several key categories. This study opens another important application area for conductive nanotube thin films.
The single-wall carbon nanotube waveguides and excitation of their σ+π plasmons by an electron beam
Authors: Nejati M. , Javaherian C. , Shokri B. , Jazi B.
Published: February 2009

By using the linearized two-fluid quantum hydrodynamic model for σ and π orbitals, the dispersion relations of electromagnetic waves in the single-walled carbon nanotubes are investigated. By injection of a relativistic electron beam, the excitation of electromagnetic waves in this system is studied. The graphs of operating frequency with respect to the accelerating voltage and time growth rate with respect to the wave number for excitation of slow electric mode waves (transverse magnetic mode waves) are presented.
Single mode microwave irradiation to improve the efficiency of polymer solar cell based on poly(3-hexylthiophene) and fullerene derivative
Authors: Yoshikawa Osamu , Sonobe Taro , Sagawa Takashi , Yoshikawa Susumu
Published: February 2009

Single mode microwave irradiation was successfully applied to improve the efficiency of polymer solar cell based on poly (3-hexylthiophene) and [6, 6]-phenyl C61-butyric acid methyl ester for the first time. Treatment at 93 °C for 4 min irradiation was possible to achieve the same effect as the thermal annealing at 150 °C for 6 min, proving this method is superior for morphology control under the mild condition. Energy conversion efficiency of 1.46% for untreated device was improved to 3.30% after microwave irradiation under the condition of AM 1.5, 100 mW/cm2.
Reversible changes of epitaxial thin films from perovskite LaNiO3 to infinite-layer structure LaNiO2
Authors: Kawai Masanori , Inoue Satoru , Mizumaki Masaichiro , Kawamura Naomi , Ichikawa Noriya , Shimakawa Yuichi
Published: February 2009

An infinite-layer-structure epitaxial thin film of LaNiO2 was prepared by low-temperature reduction with CaH2 from a LaNiO3 epitaxial thin film grown on a SrTiO3(100) substrate. The oxygen content changed reversibly from the perovskite LaNiO3 to the infinite-layer LaNiO2 without losing the structural framework and the topotactic relationship. Consequently, the oxidation state of Ni ions in the film changed from trivalent to divalent to monovalent.
Quantitative analysis of subgrain boundaries in Si multicrystals and their impact on electrical properties and solar cell performance
Authors: Kutsukake Kentaro , Usami Noritaka , Ohtaniuchi Tsuyoshi , Fujiwara Kozo , Nakajima Kazuo
Published: February 2009

We implement spatially resolved x-ray rocking curve for quantitative analysis of subgrain boundary (sub-GB) density in Si multicrystals with controlled microstructures by “dendritic casting method.” The oriented crystal grains made it possible to analyze a large area over different crystal grains by using the same optical configuration. Sub-GBs were found to be spatially localized in a particular region and spread in the growth direction of the ingot. By combining sub-GB density with a separate measurement of minority carrier diffusion length, carrier recombination velocity at sub-GBs was revealed to be at the same order as random GBs. Furthermore, by analyzing electroluminescence images of a solar cell with different detection wavelengths, sub-GBs were shown to behave as shunts with stronger activity than random GBs.
Role of stable eigenmodes in gyrokinetic models of ion temperature gradient turbulence
Authors: Hatch D. R. , Terry P. W. , Nevins W. M. , Dorland W.
Published: February 2009

Investigation of ion temperature gradient turbulence in gyrokinetic models shows that some of the key features of reduced models associated with saturation by nonlinearly excited damped eigenmodes carry over to gyrokinetics. For nonzonal wavenumbers the frequency spectrum in gyrokinetics is broader by a factor of 10 than simple nonlinear broadening of the most unstable eigenmode. The width, including its variations with wavenumber and temperature gradient scale length, closely tracks accessible stable eigenmodes as approximated by a gyro-Landau fluid model for the same parameters. Cross-phase probability distribution functions (pdfs) and fluxes show nonlinear behavior consistent with stable eigenmodes in nonzonal wavenumbers contributing to 30% of the fluctuation energy. Phase pdfs and cross-phase time histories show that multiple eigenmodes [in addition to high frequency geodesic acoustic modes (GAMs)] are a significant part of the ky=0 spectrum. Two possible roles of zonal modes in saturation are proposed. First, known nonlinearly accessible stable zonal eigenmodes (in addition to zonal flows and GAMs) are discussed and it is suggested that if these eigenmodes are excited they may be the primary arbiter of saturation. Second, zonal modes may facilitate energy transfer from unstable eigenmodes to stable eigenmodes at finite ky.
Open-flow mixing: Experimental evidence for strange eigenmodes
Authors: Gouillart E. , Dauchot O. , Thiffeault J.-L. , Roux S.
Published: February 2009

We investigate experimentally the mixing dynamics of a blob of dye in a channel flow with a finite stirring region undergoing chaotic advection. We study the homogenization of dye in two variants of an eggbeater stirring protocol that differ in the extent of their mixing region. In the first case, the mixing region is separated from the sidewalls of the channel, while in the second it extends to the walls. For the first case, we observe the onset of a permanent concentration pattern that repeats over time with decaying intensity. A quantitative analysis of the concentration field of dye confirms the convergence to a self-similar pattern, akin to the strange eigenmodes previously observed in closed flows. We model this phenomenon using an idealized map, where an analysis of the mixing dynamics explains the convergence to an eigenmode. In contrast, for the second case the presence of no-slip walls and separation points on the frontier of the mixing region leads to non-self-similar mixing dynamics.
Equilibria for anisotropic bending energies
Authors: Palmer Bennett
Published: February 2009

We study a variational problem involving an anisotropic bending energy for surfaces. Surfaces with boundary and closed equilibria are discussed.
Modeling of scalar mixing in turbulent jet flames by multiple mapping conditioning
Authors: Vogiatzaki K. , Cleary M. J. , Kronenburg A. , Kent J. H.
Published: February 2009

Multiple mapping conditioning (MMC) combines the probability density function (PDF) and the conditional moment closure (CMC) methods via the application of a generalized mapping function to a prescribed reference space. Stochastic and deterministic formulations of MMC exist, and the deterministic implementation has been applied here to a piloted jet diffusion flame (Sandia Flame D). This paper focuses on the feasibility of MMC and its closures for real (laboratory) flames and a relatively simple one-dimensional reference space that represents mixture fraction has been used. The remaining chemically reactive species are implicitly conditioned on mixture fraction and their fluctuations around the conditional mean are neglected. This work primarily evaluates the ability of the deterministic form of MMC to provide accurate and consistent closures for the mixture fraction PDF and the conditional scalar dissipation which do not rely on presumed shape functions for the PDF such as the commonly used β-PDF. Computed probability distributions agree well with measurements, and a detailed comparison of the modeled conditional and mean scalar dissipation with experimental data and conventional closures demonstrate MMC’s potential. Predictions of reactive species and temperature are in good agreement with experimental data and similar in quality to singly conditioned, first-order CMC predictions. MMC therefore provides an attractive-since consistent-alternative approach for the modeling of scalar mixing in turbulent reacting flows.
Nonconventional quasineutral mode of carrier transport in semiconductors and semiconductor structures
Authors: Mnatsakanov T. T. , Tandoev A. G. , Yurkov S. N. , Levinshtein M. E.
Published: February 2009

It is demonstrated that, in addition to the well-known quasineutral modes of carrier transport, i.e., those of quasineutral diffusion and quasineutral drift, a quasineutral mode of diffusion stimulated by quasineutral drift (DSQD) is possible. An equation that describes this mode is derived and the principal specific features of the mode are examined analytically. In particular, an analytical expression for the current-voltage (I-V) characteristic is obtained for the case when just DSQD governs the carrier transport. The analytical results obtained are verified and confirmed by a detailed simulation.
Optimal paths for minimizing entropy generation during heat transfer processes with a generalized heat transfer law
Authors: Chen Lingen , Xia Shaojun , Sun Fengrui
Published: February 2009

An investigation of finite-time heat transfer processes between high- and low-temperature sides with a generalized heat transfer law (q∝[Δ(Tn)]m) is presented in this paper. Optimal heating and cooling strategies for minimizing entropy generation are derived for the fixed initial and final temperatures of the low-temperature side working fluid. Optimal paths are compared with the common strategies of constant heat flux and constant source temperature operation by numerical examples. The condition corresponding to the minimum entropy generation strategy is not only valid for Newton’s [q∝(ΔT)] and linear phenomenological [q∝Δ(T−1)] heat transfer laws but also valid for heat transfer law (q∝[Δ(T−1)]m). The obtained results are general and can provide some theoretical guidelines for the designs and operations of practical heat exchangers.
Impedance e-tongue instrument for rapid liquid assessment
Authors: Cabral Flávio P. A. , Bergamo Bruno B. , Dantas Cleber A. R. , Riul A. , Giacometti José A.
Published: February 2009

We present a compact and easy to handle instrument developed to perform rapid analysis of liquids utilizing an “electronic tongue” system. Briefly, the e-tongue used here is based on impedance measurements of an array of sensing units fabricated with ultrathin films of different materials deposited onto gold interdigitated electrodes. The instrument has the capability of measuring up to eight different sensor sets, each comprising an array of eight sensing units, and can perform a series of measurements in less than half of an hour. Additionally, there is a user-friendly software interface for instrument control, allowing the statistical correlation of samples using principal component analysis.
Electroactive hydrodynamic weirs for microparticle manipulation and patterning
Authors: Taff Brian M. , Desai Salil P. , Voldman Joel
Published: February 2009

We present a platform for parallelized manipulations of individual polarizable micron-scale particles (i.e., microparticles) that combines negative dielectrophoretic forcing with the passive capture of hydrodynamic weir-based trapping. Our work enables manipulations using ejection- and/or exclusion-based methods. In ejection operations, we unload targeted weirs by displacing microparticles from their capture faces via electrode activation. In exclusion-based operations, we prevent weir loading by activating selected on-chip electrodes before introducing microparticles into the system. Our work describes the device’s passive loading dynamics and demonstrates enhanced functionalities by forming a variety of particle patterns.
Wideband low-noise optical beam deflection sensor with photothermal excitation for liquid-environment atomic force microscopy
Authors: Fukuma Takeshi
Published: February 2009

I developed a wideband low-noise optical beam deflection sensor with a photothermal cantilever excitation system for liquid-environment atomic force microscopy. The developed sensor has a 10 MHz bandwidth and 4.7 fm/Hz deflection noise density in water. The theoretically limited noise performance (i.e., the noise level limited only by the photodiode shot noise) has been achieved in liquid for the first time. Owing to the wide bandwidth and the replaceable focus lens design, the sensor is applicable to cantilevers with various dimensions. The deflection noise densities of less than 7.8 fm/Hz have been achieved in water for cantilevers with lengths from 35 to 125 μm. The ideal amplitude and phase versus frequency curves without distortion are obtained with the developed photothermal excitation system. The excitation system is applicable to relatively stiff cantilevers (>20 N/m) in liquid, making it possible to obtain true atomic-resolution images in liquid. True atomic-resolution imaging of mica in water is demonstrated using the developed deflection sensor and the photothermal excitation system.