bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrical time-domain observation of magnetization switching induced by spin transfer in magnetic nanostructures (invited)
Authors: Devolder T. , Hayakawa J. , Ito K. , Takahashi H. , Ikeda S. , Katine J. A. , Carey M. J. , Crozat P. , Kim J. V. , Chappert C. , Ohno H.
Published: March 2008

We have measured the distribution of switching times in spin-transfer switching induced by fast current pulses in two pillar-shaped systems: (i) spin valves and (ii) MgO-based magnetic tunnel junctions. (i) Spin valves can sustain high currents, such that the application of pulsed currents of amplitude a few times that of the static switching threshold is possible. This makes subnanosecond switching within reach. In that limit, the pulse durations leading to switching follow a multiply stepped distribution at 300K and a regular distribution at 40K. At 300K, this reflects the precessional nature of the switching, which proceeds through a small number of precession cycles. The switching time distribution can be modeled from the thermal variance of the initial magnetization orientations. At 40K, nonuniform magnetization switching occurs. (ii) In MgO-based tunnel junctions, we could follow individual time-resolved switching events with a 13GHz bandwidth. The switching proceeds through a nanosecond-scale random incubation delay during which the resistance is quiet, followed by a sudden (400ps duration) transition terminated by a pronounced ringing that is damped within 1.5ns. While the incubation delay is probabilistic, the following time dependence of the resistance is reproducible.
Relationship between composite and imperfect materials in perpendicular recording media (invited)
Authors: Victora R. H. , Kapoor Manish , Hamre Alyssa K. , Hernandez Stephanie
Published: March 2008

It is common to model recording media as interacting coherently rotating magnetic moments, but real materials frequently exhibit perpendicular switching fields less than the anisotropy field and a different angular dependence than theoretically expected. Micromagnetic simulations were performed, which included multiple elements per grain and magnetostatic interactions between elements. Two likely explanations have emerged from this analysis: the existence of low anisotropy regions within the first few atomic layers of the sputtered film or anisotropy gradation throughout the grain thickness. Both explanations offer appropriate coercivity reductions; however, grains including anisotropy gradation display this effect at more realistic values of intragranular exchange. A simplified two element model was fit to the multidomain angle-dependent results in order to find a computationally simple description that can be easily included in a recording simulation.
Exploiting finite size effects in a novel core/shell microstructure
Authors: Liu Zhu , Xia Guoqiang , Zhu Frank , Kim Su , Markovic Nina , Chien Chia-Ling , Searson Peter C.
Published: March 2008

Electrodeposition of Ni–Cu alloys at high Cu(II) concentration and large overpotentials results in phase separation with a unique microstructure characterized by features with a copper-rich core and a nickel-rich shell. By confining deposition to nanoporous channels with dimensions comparable to or smaller than the grain size results in the formation of solid Ni–Cu nanowires with a copper-rich core and a nickel-rich shell. Etching of the copper-rich core results in the formation of Ni-rich nanotubes. The magnetic properties of the Ni–Cu nanowires and the Ni nanotubes are investigated.
Nonlinearities in composition dependence of structure parameters and magnetic properties of nanocrystalline fcc/bcc-mixed Co–Ni–Fe thin films
Authors: Chechenin N. G. , Khomenko E. V. , Vainchtein D. I. , De Hosson J. Th. M.
Published: March 2008

In this report, the nonlinearities are analyzed in fcc-to-bcc (fcc/bcc) population ratio, lattice parameters (aexpfcc∕aidealfcc and aexpbcc∕aidealbcc) and saturation magnetization (ISobs∕ISa) of the electrodeposited thin Co–Fe–Ni films as a function of average number of electrons in the alloy (ne), which proved to be a convenient way to follow the variation of chemical composition. The enhancement of the saturation magnetization correlated with the nonlinear deformation and connected with a complicated rearrangement of the outer shell electron configurations due to change in composition in a disordered alloy.
Co
Cr
Pt
–
Si
O
2
granular-type longitudinal media on Ru underlayer for sputtered tape applications
Authors: Lee Hwan-Soo , Zhu Jian-Gang , Laughlin David E.
Published: March 2008

Co Cr Pt – Si O 2 films for use as thin film tape media have been investigated. Bias sputtering and high Ar pressure were utilized to achieve desirable media properties (good in-plane orientation and enhanced grain decoupling) in these media. The in-plane orientation of the bias sputtered CoCrPt–SiO2 magnetic layer was well maintained even at a high content of SiO2 as Ru was used as an underlayer and deposited at high Ar pressure. Films of (10.0) textured CoCrPt–SiO2 on a Ru underlayer showed a large in-plane coercivity of 4000Oe and transmission electron microscopy revealed an average grain size of about 10nm, well decoupled by the oxide. The in-plane coercivity was a strong function of the Ru thickness.
Magnetic properties of a necklace spin ladder
Authors: Cheranovskiĭ V. O. , Ezerskaya E. V.
Published: March 2008

The bottom part of the spectrum of a diagonal necklace spin ladder (s=1∕2) (NL) with spatial and spin anisotropy of neighboring interactions is studied using perturbation theory and numerical calculations which are performed by the Davidson and DMRG methods. It is shown that a first-order phase transition exists at zero temperature with respect to the spin anisotropy parameter, accompanied by a macroscopic jump in the magnetization. It is also shown that a plateau can appear in the field dependence of the magnetization with the z projection of the total spin M=1∕3Mmax as a result of the gap character of the excitations, which increase M. The amplitude of the spin wave characterizing the ground state of the NL with different isotropic spin interaction constants inside and between the cells takes on its maximum value when all interactions are the same.
Contribution to the theory of the interaction of electromagnetic radiation with a Bose-Einstein condensate of magnons
Authors: Loktev V. M.
Published: March 2008

An attempt is made to analyze the dependence of the Raman scattering cross section or the absorption∕emission of electromagnetic waves by a Bose-Einstein condensate of magnons on their (magnons) density. Specifically, the intensities of one- and two-magnon transitions are compared and it is concluded that latter dominate in a Bose condensate. The salient features and possible role of the intermagnon interaction are discussed briefly.
Dynamical solitons in a spin S=1 ferromagnet
Authors: Ivanov B. A. , Khimin R. S.
Published: March 2008

A semiclassical theory of the spin dynamics for a ferromagnet with spin S=1 is constructed taking account of the isotropic exchange interaction. For such a ferromagnet in the ground state the quantum average value m of the spin at a site takes its maximum value, but the effects of a quantum reduction of the spin are strongly manifested in dynamics. However, for such ferromagnets there exists a special class of spin oscillations in which the direction of m is maintained but the length of m change substantially. Such excitations are absent for ordinary Heisenberg ferromagnets, whose description is based on the Landau–Lifshitz equation or on the standard Heisenberg spin Hamiltonian. Spin excitations with finite energy, or solitons, which can be regarded as bound states of a large number N of magnons, are obtained analytically in the continuum approximation and numerically. The dependence of the energy E(P,N) of a soliton with a fixed number of bound magnons on its momentum P is found. The continuum approximation gives a good description of solitons in this range of parameters, where the magnetization in a soliton differs substantially from the neighboring lattice sites and effects due to discreteness should be substantial.
Two-region model for positive and negative plasma sheaths and its application to Hall thruster metallic anodes
Authors: Ahedo E. , Escobar D.
Published: March 2008

An asymptotic presheath/sheath model for positive and negative sheaths in front of a conducting electrode, with a continuous parametric transition at the no-sheath case, is presented. Key aspects of the model are as follows: full hydrodynamics of both species in the presheath; a kinetic formulation with a truncated distribution function for the repelled species within the sheath; and the fulfillment of the marginal Bohm condition at the sheath edge, in order to match the two formulations of the repelled species. The sheath regime depends on the ratios of particle fluxes and sound speeds between the two species. The presheath model includes the effect of a magnetic field parallel to the wall on electrons. An asymptotic, parametric study of the anode presheath is carried out in terms of the local ion-to-electron flux ratio and Hall parameter. The drift-diffusive model of magnetized electrons fails in a parametric region that includes parts of the negative sheath regime. In the case of the Hall parameter vanishing near the electrode and a weakly collisional plasma, a quasisonic, quasineutral plateau forms next to the sheath edge.
Ionic cluster effect in suppression of superconductivity in Ni- and Co-doped YBCO systems
Authors: Wang A. , Wang X. , Cao Y. , Li X. , Wang Y. , Gao L. , Lu H. , Zhang J. , Li P.
Published: March 2008

The system YBa2Cu3−x(Ni,Co)xO7−δ with x=0–0.5 is investigated comprehensively by x-ray diffraction, oxygen-content, and positron annihilation technology as well as simulation methods. The simulation results show that the dopant ions are distributed dispersely at low concentrations. As the dopant concentration increases, the ions combine into clusters in the crystal lattice. The calculated results and oxygen contents, together with the impurity phases and the local electron density ne, show an ionic cluster effect, which not only causes the local electron density to reach saturation but also suppress the superconductivity significantly.
On existence of a paramagnetic contribution to the susceptibility of a mesoscopic cylindrical normal metal–superconductor structure
Authors: Gogadze G. A.
Published: March 2008

The density of states N(ε) of a mesoscopic cylindrical structure consisting of a normal pure metal and a superconductor is calculated using the Gorkov–Green functions. It is shown that magnetic fluxes of certain values cause resonance spikes of N(ε), suggesting a large-amplitude paramagnetic contribution which accounts for the reentrant effect detected by P. Visani, A. C. Mota, and A. Pollini, Phys. Rev. Lett. 65, 1514 (1990).
Distinctive effects of a spin-polarized current on the static and dynamic properties of an antiferromagnetic conductor
Authors: Gomonaĭ E. V. , Loktev V. M.
Published: March 2008

A phenomenological model is developed to describe the effect of a spin-polarized current on the properties of an antiferromagnetic metal. It is shown that the spin-polarized current induced spin torque depends on the antiferromagnetism vector and therefore plays an important role in magnetic dynamics. Analysis of the dynamical equations obtained in this paper indicates that diverse effects similar to those observed in ferromagnets, for example, instability of definite directions and precession of the antiferromagnetic moment around the “hard” axis, could exist. In contrast to ferromagnets, a spin-polarized current in antiferromagnetic metals influences the spin-wave spectrum and can give rise to parametric resonance and a spin-flop transition. The results obtained are used to interpret the recently observed gigantic magnetoresistance of an antiferromagnetic nature.
Low-amplitude jump-like deformation of Pb–In alloys in the superconducting state
Authors: Lebedev V. P. , Krylovskiĭ V. S. , Lebedev S. V. , Savich S. V.
Published: March 2008

Plastic-flow instability in the form of low-amplitude 10−2–10−1MPa aperiodic jumps of the deforming stress has been observed and investigated during the deformation of polycrystals of the alloys Pb–(20–55)at.%In in the superconducting state. The amplitude and number of stress jumps were studied as a function of the state of the metal (normal or superconducting) and the degree of distortion of the crystal lattice as a result of intrinsic and extrinsic defects. Possible mechanisms for in the low-amplitude jump-like deformation of the alloy are discussed.
Optically stimulated desorption of “hot” excimers from pre-irradiated Ar solids
Authors: Gumenchuk G. B. , Khyzhniy I. V. , Bludov M. A. , Uyutnov S. A. , Belov A. G. , Savchenko E. V. , Ponomaryov A. N. , Bondybey V. E.
Published: March 2008

Electronically induced desorption from solid Ar pre-irradiated by a low-energy electron beam is investigated by activation spectroscopy methods —photon-stimulated exoelectron emission and photon-stimulated luminescence in combination with spectrally resolved measurements in the VUV range of the spectrum. Desorption of vibrationally excited argon molecules Ar2*(ν) from the surface of pre-irradiated solid Ar is observed for the first time. It is shown that desorption of “hot” Ar2*(ν) molecules is caused by recombination of self-trapped holes with electrons released from traps by visible-range photons. The possibility of optical stimulation of the phenomenon is evidenced.
Born–Oppenheimer approximation and beyond for time-dependent electronic processes
Authors: Cederbaum L. S.
Published: March 2008

Explicit computations of electronic motion in time and space are gradually becoming feasible and available. The knowledge of this motion is of relevance by itself but is also important for understanding available and predicting future experiments on the electronic time scale. In electronic processes of interest, usually several and even many stationary electronic states participate and the obvious question arises on how to describe the accompanying quantum nuclear dynamics at least on the time scale of the process. In this work, we attempt to study the nuclear dynamics in the framework of a fully time-dependent Born–Oppenheimer approximation. Additionally, we attempt to go beyond this approximation by introducing the coupling of several electronic wavepackets by the nuclear wavepackets. In this context, we also discuss a time-dependent transformation to diabatic electronic wavepackets. A simple but critical model of charge transfer is analyzed in some detail on various levels of approximation and also solved exactly.
Density profiles of Ar adsorbed in slits of CO2: Spontaneous symmetry breaking revisited
Authors: Szybisz Leszek , Sartarelli Salvador A.
Published: March 2008

A recently reported symmetry breaking of density profiles of fluid argon confined by two parallel solid walls of carbon dioxide is studied. The calculations are performed in the framework of a nonlocal density functional theory. It is shown that the existence of such asymmetrical solutions is restricted to a special choice for the adsorption potential, where the attraction of the solid-fluid interaction is reduced by the introduction of a hard-wall repulsion. The behavior as a function of the slit’s width is also discussed. All the results are placed in the context of the current knowledge on this matter.
Characterization of a polarization-resolved high spectral resolution UV-visible spectrometer
Authors: Kim J. , Kim D.
Published: March 2008

To measure the degree of polarization of a plasma emission, a polarization-resolved UV-visible Czerny–Turner-type spectrometer was designed and constructed. For a high spectral resolution, F=1m mirrors were used as a focusing and collimating mirrors and the incidence angles to the mirrors were determined to eliminate coma. The effect of astigmatism was reduced by designing the incidence angles to the mirrors to be as small as possible. The flat focal plane condition proposed by Reader [J. Opt. Soc. Am. 59, 1189 (1969)] was used to determine the grating position. The measured spatial resolution was 170μm. To simultaneously measure the intensities with two perpendicular polarizations, a calcite crystal was placed after the entrance slit of the spectrometer. The change in the imaging property of the spectrometer due to the calcite crystal was measured and minimized. The spectral resolution was experimentally measured with a laser produced plasma to be 0.05nm at 348nm. The resolving power measured is 6600.
Physical properties of Hastelloy® C-276™ at cryogenic temperatures
Authors: Lu J. , Choi E. S. , Zhou H. D.
Published: March 2008

In recent years, the Ni–Mo–Cr superalloy Hastelloy® C-276™ has been used as a substrate material for fabricating superconducting tapes such as YBCO and MgB2 coated conductors. With increasing piece length, these coated conductors are within reach of large scale commercial applications. However, data on the physical properties of Hastelloy C-276 at temperatures relevant for these applications are not yet available. In this work, physical properties including magnet succeptibility, specific heat, electrical resistivity, and the Seebeck coefficient are measured from 2to300K and thermal conductivity from 2to200K. Our results show that Hastelloy C-276 exhibits Curie paramagnetism between 4 and 300K with a Curie constant C=0.091K. A spin-glass-like behavior is observed below 3K. The electrical resistivity has a minimum at ∼12K, and shows a linear weak T dependence at higher temperatures. The specific heat Cp between 15 and 40K follows Cp=γT+AT3. Below ∼10K, an upturn in Cp∕T with decreasing T is interpreted by the existence of very small ferromagnetic clusters. We found relatively strong phonon contribution to the thermal conductivity in the measured temperature range. In addition, we present the thermal diffusivity as a function of temperature calculated from the thermal conductivity and the Cp data. The Seebeck coefficient is found to be proportional to temperature. The results of our measurements provide important data not only for the specific applications of the superconducting coated conductors that use Hastelloy C-276 as substrates, but also for many other potential cryogenic temperature applications.
Precise selective deposition of microparticles on electrodes of microelectronic chips
Authors: Nesterov Alexander , König Kai , Felgenhauer Thomas , Lindenstruth Volker , Trunk Ulrich , Fernandez Simon , Hausmann Michael , Ralf Bischoff F. , Breitling Frank , Stadler Volker
Published: March 2008

We examined the high precision deposition of toner and polymer microparticles with a typical size of ∼10μm on electrode arrays with electrodes of 100μm and below using custom-made microelectronic chips. Selective desorption of redundant particles was employed to obtain a given particle pattern from preadsorbed particle layers. Microparticle desorption was regulated by dielectrophoretic attracting forces generated by individual pixel electrodes, tangential detaching forces of an air flow, and adhesion forces on the microchip surface. A theoretical consideration of the acting forces showed that without pixel voltage, the tangential force applied for particle detachment exceeded the particle adhesion force. When the pixel voltage was switched on, however, the sum of attracting forces was larger than the tangential detaching force, which was crucial for desorption efficiency. In our experiments, appropriately large dielectrophoretic forces were achieved by applying high voltages of up to 100V on the pixel electrodes. In addition, electrode geometries on the chip’s surface as well as particle size influenced the desorption quality. We further demonstrated the compatibility of this procedure to complementary metal oxide semiconductor chip technology, which should allow for an easy technical implementation with respect to high-resolution microparticle deposition.
Phase modulation atomic force microscopy in constant excitation mode capable of simultaneous imaging of topography and energy dissipation
Authors: Li Yan Jun , Kobayashi Naritaka , Naitoh Yoshitaka , Kageshima Masami , Sugawara Yasuhiro
Published: March 2008

The authors have developed phase modulation atomic force microscopy in constant excitation mode capable of simultaneously imaging the topography and energy dissipation of a sample surface in a liquid. This setup utilizes a fast, low-cost sample-and-hold technique to analyze the oscillation signals of a cantilever. The proposed circuitry allows us to measure the local energy dissipated by the tip-sample interaction during imaging. The energy dissipation image exhibits a material-specific contrast for a polymer-blend film.
Local measurements of the diffusion constant in multiple scattering media: Application to human trabecular bone imaging
Authors: Aubry Alexandre , Derode Arnaud , Padilla Frédéric
Published: March 2008

We present local measurements of the diffusion constant for ultrasonic waves undergoing multiple scattering. The experimental setup uses a coherent array of programmable transducers. By achieving Gaussian beamforming at emission and reception, an array of virtual sources and receivers located in the near field is constructed. A matrix treatment is proposed to separate the incoherent intensity from the coherent backscattering peak. Local measurements of the diffusion constant D are then achieved. This technique is applied to a real case: a sample of human trabecular bone for which the ultrasonic characterization of multiple scattering is an issue.
Design of a compensated signal rod for low magnetic moment sample measurements with a vibrating sample magnetometer
Authors: Carignan Louis-Philippe , Cochrane Robert W. , Ménard David
Published: March 2008

A zero-signal sample holder is proposed for the measurement of weak magnetic signals with vibrating sample magnetometers. With proper shape of the support rod, a nearly vanishing signal can be obtained as a function of the magnetic field and the temperature. In particular, it is shown that the addition of an extra part to a standard glass sample holder can reduce the diamagnetic signal by more than three orders of magnitude with no noise increase. The proposed method is applicable to field, temperature, and angular measurements; it is also ideally suited to direct measurement of nanometer thick magnetic layers deposited on much thicker diamagnetic substrates.
Sensitized near infrared emission from lanthanide-exchanged zeolites
Authors: Monguzzi A. , Macchi G. , Meinardi F. , Tubino R. , Burger M. , Calzaferri G.
Published: March 2008

In this work, we present an alternative approach to sensitize the near infrared emission of Er3+ ions (used in telecom applications) by exploiting the geometrical confinement occurring in porous zeolites structures. The sensitization of the Ln ion is obtained by energy transfer between a suitable organic molecule acting as an antenna and the emitting ion arranged in closed proximity, thus, avoiding the limits imposed by the coordination chemistry.
The effect of nitrogen concentration on the band gap and band offsets of HfOxNy gate dielectrics
Authors: Wang X. J. , Zhang L. D. , Liu M. , Zhang J. P. , He G.
Published: March 2008

The effect of N concentration on the band gap and band offsets of HfOxNy films has been systematically investigated. It was found that the band gap as well as the band offsets of HfOxNy films decreased with the increase of N concentration. When the N concentration reached 16.3%, the conduction band offset (ΔEc) reduced to be 0.88eV, which is smaller than the minimal requirement of ΔEc values for high-k dielectrics and, thus, leads to unacceptably high leakage currents. Therefore, nitrogen concentration should be carefully controlled to guarantee excellent properties of nitrogen incorporated high-k dielectrics.
Internal voltages in GaInP∕GaInAs∕Ge multijunction solar cells determined by electroluminescence measurements
Authors: Kirchartz Thomas , Rau Uwe , Hermle Martin , Bett Andreas W. , Helbig Anke , Werner Jürgen H.
Published: March 2008

We analyze electroluminescence spectra of a GaInP∕GaInAs∕Ge triple-junction solar cell at different injection currents. Using the reciprocity theorem between electroluminescent emission and external quantum efficiency of solar cells allows us to derive the current/voltage curves and the diode quality factors of all individual subcells.
Dissection of the essential steps for condensin accumulation at kinetochores and rDNAs during fission yeast mitosis
Authors: Nakazawa Norihiko , Nakamura Takahiro , Kokubu Aya , Ebe Masahiro , Nagao Koji , Yanagida Mitsuhiro
Published: March 2008

The condensin complex has a fundamental role in chromosome dynamics. In this study, we report that accumulation of Schizosaccharomyces pombe condensin at mitotic kinetochores and ribosomal DNAs (rDNAs) occurs in multiple steps and is necessary for normal segregation of the sister kinetochores and rDNAs. Nuclear entry of condensin at the onset of mitosis requires Cut15/importin α and Cdc2 phosphorylation. Ark1/aurora and Cut17/Bir1/survivin are needed to dock the condensin at both the kinetochores and rDNAs. Furthermore, proteins that are necessary to form the chromatin architecture of the kinetochores (Mis6, Cnp1, and Mis13) and rDNAs (Nuc1 and Acr1) are required for condensin to accumulate specifically at these sites. Acr1 (accumulation of condensin at rDNA 1) is an rDNA upstream sequence binding protein that physically interacts with Rrn5, Rrn11, Rrn7, and Spp27 and is required for the proper accumulation of Nuc1 at rDNAs. The mechanism of condensin accumulation at the kinetochores may be conserved, as human condensin II fails to accumulate at kinetochores in hMis6 RNA interference–treated cells.
Building the actin cytoskeleton: filopodia contribute to the construction of contractile bundles in the lamella
Authors: Nemethova Maria , Auinger Sonja , Small J. Victor
Published: March 2008

Filopodia are rodlike extensions generally attributed with a guidance role in cell migration. We now show in fish fibroblasts that filopodia play a major role in generating contractile bundles in the lamella region behind the migrating front. Filopodia that developed adhesion to the substrate via paxillin containing focal complexes contributed their proximal part to stress fiber assembly, and filopodia that folded laterally contributed to the construction of contractile bundles parallel to the cell edge. Correlated light and electron microscopy of cells labeled for actin and fascin confirmed integration of filopodia bundles into the lamella network. Inhibition of myosin II did not subdue the waving and folding motions of filopodia or their entry into the lamella, but filopodia were not then integrated into contractile arrays. Comparable results were obtained with B16 melanoma cells. These and other findings support the idea that filaments generated in filopodia and lamellipodia for protrusion are recycled for seeding actomyosin arrays for use in retraction.
Taking apart the endocytic machinery
Authors: Kaksonen Marko
Published: March 2008

The formation of clathrin-coated endocytic vesicles is driven by a complex and highly dynamic molecular machinery. In this issue, Idrissi et al. (Idrissi, F.-Z., H. Grötsch, I.M. Fernández-Golbano, C. Presciatto-Baschong, H. Riezman, and M.-I. Geli. 2008. J. Cell Biol. 180:1219–1232) reveal some of the secrets of this machinery by analyzing the localizations of nine endocytic proteins during vesicle budding in yeast using quantitative immunoelectron microscopy.
Some Observations on the Migration of Proteus mirabilis and Other Urinary Tract Pathogens Over Foley Catheters
Authors: Williams Gareth J. , Stickler David J.
Published: March 2008

The ability of uropathogens to migrate along external surfaces of silicone Foley catheters was examined. Proteus mirabilis and Pseudomonas aeruginosa were the most motile organisms. P. aeruginosa migrated over both triclosan-impregnated and nitrofurazone-impregnated catheters, but these antibacterials inhibited the migration of P. mirabilis.
Incidence of Methicillin-Resistant Staphylococcus aureus Nosocomial Infections in Intensive Care Units in Lyon University Hospitals, France, 2003-2006
Authors: Moalla M. , Baratin D. , Giard M. , Vanhems P.
Published: March 2008

We describe the trends in the incidence of methicillin-resistant Staphylococcus aureus nosocomial infection in intensive care units in Lyon hospitals from January 1, 2003, through December 31, 2006. The incidence rate decreased from 1.77 cases per 100 ICU patients in 2003 to 1.16 cases per 100 ICU patients in 2006, a reduction of 38.0% (P = .05).
A multi‐center survey of childhood asthma in Turkey – I: The cost and its determinants
Authors: Beyhun Nazim E. , Soyer Özge U. , Kuyucu Semanur , Sapan Nihat , Altıntaş Derya U. , Yüksel Hasan , Anlar Fehmi Y. , Orhan Fazil , Cevit Ömer , Çokuğras Haluk , Boz Ayşen B. , Yazıcıoğlu Mehtap , Tanaç Remziye , Şekerel Bülent E.
Published: March 2008

Successful management of childhood asthma requires a thorough idea of the economic impact of asthma and its determinants, as policy makers and physicians inevitably influence the outcome. The aim of this study was to define the cost of childhood asthma in Turkey and its determinants. In April 2006, a multi‐center, national study was performed where data regarding cost and control levels were collected. Asthmatic children (6–18 yr) with at least a 1‐yr follow‐up seen during a 1‐month period with scheduled or unscheduled visits were included. The survey included a questionnaire‐guided interview and retrospective evaluation of files. Cost and its determinants during the last year were analyzed. A total of 618 children from 12 asthma centers were surveyed. The total annual cost of childhood asthma was US$1597.4 ± 236.2 and there was a significant variation in costs between study centers (p < 0.05). Frequent physician visits [odds ratio (95% confidence intervals)] [2.3 (1.6–3.4)], hospitalization [1.9 (1.1–3.3)], asthma severity [1.6 (1.1–2.8)], and school absenteeism due to asthma [1.5 (1.1–2.1)] were major predictors of total annual costs (p < 0.05 for each). The comparable cost of asthma among Turkish children with that reported in developed countries suggests that interventions to decrease the economic burden of pediatric asthma should focus on the cost‐effectiveness of anti‐allergic household measures and on improving the control levels of asthma.
Different Types of Postpartum Luteal Activity Affected by the Exposure of Heat Stress and Subsequent Reproductive Performance in Holstein Lactating Cows
Authors: Kornmatitsuk B , Chantaraprateep P , Kornmatitsuk S , Kindahl H
Published: March 2008

Contents

The aim of the present study was to determine the effect of heat stress on postpartum (PP) luteal activity and subsequent reproductive performance in lactating cows. Thirty Holstein–Friesian (HF, ≥75%) cows (hot season, n = 15 and cool season, n = 15) were studied over 60 days after calving. The changes of temperature‐humidity index (THI) were monitored within both seasons. Body condition scores (BCS), uterine involution and the ovarian structures were recorded. Plasma samples were obtained three times a week for the analysis of progesterone (P4) and prostaglandin F2α metabolite (PG metabolite). Subsequent reproductive performance of the cows, calved within the same period was also evaluated. The means of THI for hot and cool seasons varied between 84–87 and 78–83 respectively. A drop of the mean BCS was recorded at 5 weeks PP in the cows during hot season (p < 0.01), however a delay of uterine involution during early PP period in hot season was not clearly seen. The cows with normal PP ovarian cyclicity during hot and cool seasons were 4/15 (26.7%) and 9/15 (60.0%) respectively. A higher percentage of abnormal luteal activity was found in the cows during hot season (p = 0.07) and delayed luteal cyclicity/anovulation was the most pronounced atypical P4 profile. The levels of PG metabolite were not different between groups and the relationship between the levels of PG metabolite and the time of uterine involution was not evident (p > 0.05). The heat detection rates and the pregnancy rates were higher in the cows during cool season (p < 0.05). Additionally, the higher first AI conception rates during cool season were recorded (p = 0.06). In conclusion, heat stress conditions had negative effects on BCS and altered a normal process of ovarian resumption PP, consequently resulted in lower reproductive performance in a tropical dairy herd.
A Study on Postpartum Metritis in Iraqi Buffalo Cows: Bacterial Causes and Treatment
Authors: Azawi OI , Omran SN , Hadad JJ
Published: March 2008

Contents

The objectives of the present study were to determine the relationship between bacteriological findings, clinical signs and histopathological changes in postpartum metritis. Evaluation of the treatment efficiency of using systemic or intra‐uterine infusion of antibiotics with some hormonal preparations for the treatment of postpartum metritis. Data were collected from 50 buffalo cows with history of calving of more than 1 month. All buffaloes were subjected to detailed clinical examination including external inspection, vaginoscopy and transrectal palpation of the cervix, uterus and ovaries. Swabs for bacteriology and biopsies for histopathology were collected from uterine lumen from each buffalo included in the present study. Bacteria identified using API systems following aerobic and anaerobic cultures. Vaginal mucus scored for character, odour and estimation of polymorphonuclear cells (PMNs). Treatment conducted using oxytetracycline in local intrauterine infusion or systemically with hormonal treatment including prostaglandinF2α (PGF2α) and oestradiol benzoate. Results revealed that the most predisposing factor for postpartum uterine infection was retained placenta and toxic puerperal metritis. The most prevalent bacteria in uterine lumen were Escherichia coli, Archanobacterium pyogenes, Bacteroides fragilis and Fusobacterium necrophorum the most prevalent bacteria in buffaloes with postpartum metritis. A. pyogenes and F. necrophorum were an important pathogens causing severe uterine inflammation as found in histopathological examinations. Buffaloes with postpartum metritis showed good clinical cure when oxytetracycline injected systemically with PGF2α. Intrauterine infusion of oxytetracycline had no advantage for the treatment of uterine infection in buffalo cows with postpartum metritis. PGF2α improved clinical cure of buffaloes with postpartum metritis.
The Relationship Among Vitamin C, β‐carotene, Vitamin A, Progesterone and Oestradiol 17‐β Concentrations in Plasma and Cyst Fluid of Holstein Cows with Ovarian Cyst
Authors: Haliloglu S , Erdem H , Serpek B , Tekeli T , Bulut Z
Published: March 2008

Contents

The aims of this study were to determine the concentrations of the progesterone, oestradiol‐17‐β, vitamin A, C and β‐carotene in plasma and cyst fluid and to relate these values with cystic diameter and membrane thickness of Holstein cattle with ovarian luteal cyst. 1650 Holstein cows were examined for the presence of the ovarian cyst and luteal and follicular cystic ovaries were obtained following slaughtering in personal slaughterhouse in Konya‐Turkey. 15 Luteal and 15 follicular cystic ovaries were distinguished by rectal palpation and by post mortem ultrasonographic examination. Plasma and cyst fluid, hormone and vitamin analyses were carried out by EIA method and spectrophotometric measurement respectively. Although there was no relationship between β‐carotene and vitamin A in plasma and cyst fluid of both cyst type and hormone concentrations, the vitamin C concentration of cyst fluid was found significantly higher in luteal cyst than in follicular cyst. Moreover, there is a positive correlation among values of the vitamin C concentrations of cyst fluid and cystic membrane thickness, plasma and the cyst fluid progesterone concentrations, but there is a negative correlation among the vitamin C concentrations of cystic fluid and oestradiol 17β levels of plasma and cyst fluid. In conclusion, vitamin C concentration of cyst fluid supported ultrasonographic and endocrinologic findings. Also, it can be postulated that vitamin C is probably effective on progesterone synthesis in the luteal tissue of cyst.
IGG4‐RELATED SCLEROSING LYMPHOPLASMACYTIC PANCREATITIS AND CHOLANGITIS MIMICKING CARCINOMA OF PANCREAS AND KLATSKIN TUMOUR
Authors: Cheung Moon‐Tong , Lai‐Oi Lo Irene
Published: March 2008

Background:  Autoimmune sclerosing pancreatitis is a well‐known disease entity for years, particularly recognizing the difficulty in distinguishing it from malignancy. Immunohistochemical study showed that immunoglobulin IgG4 staining was positive in plasma cells of some autoimmune pancreatitis or cholangitis. The term ‘autoimmune sclerosing pancreatocholangitis’ was used as it was believed that they belonged to a range of disease involving both pancreas and biliary tree. It may also be part of a systemic fibro‐inflammatory disease.

Patients and Methods:  All the patients suffering from immunoglobulin G4 (IgG4)‐related pancreatitis and cholangitis from May 2003 to September 2006 in Queen Elizabeth Hospital, Hong Kong were retrospectively studied.

Results:  A total of five patients with clinical diagnosis of IgG4‐related autoimmune pancreatitis or cholangitis were analysed. All presented with jaundice or abdominal pain, mimicking carcinoma. Two patients had major resection, two patients were diagnosed by intraoperative biopsy and one was based on serum IgG4 level.

Conclusion:  With the growing awareness of this relatively recently characterized clinical entity and its similar presentation to pancreatic carcinoma or bile duct cholangiocarcinoma, it is important for autoimmune sclerosing pancreatocholangitis to be included in the differential diagnosis of pancreaticobiliary disease. The management strategy has shown to be modified – from major resection to intraoperative biopsy and to the assay of serum IgG4 level without the necessity of histology confirmation.
EFFECT OF MULTIORGAN DONATION AFTER CARDIAC DEATH RETRIEVAL ON LUNG PERFORMANCE
Authors: Snell Gregory I. , Levvey Bronwyn , Oto Takahiro , McEgan Robin , Mennan Mark , Eriksson Leif , Williams Trevor , Rosenfeldt Franklin
Published: March 2008

Aim:  For donation after cardiac death (DCD) transplantation to achieve its full potential, multiorgan retrieval is desirable. Although there are several novel individual techniques recently described for DCD lung donation, they have not been evaluated or compared in a DCD multiorgan scenario.

Description:  This study describes (i) the technical aspects and (ii) early lung and abdominal organ performance of several combinations of DCD donor liver, kidney and lung retrieval techniques that would mimic common DCD clinical scenarios.

Evaluation:  Lung oxygenation, urine production, bile production and biochemical measures were assessed as the outcome of a complex ex vivo lung, liver and kidney perfusion DCD model.

Conclusion:  Successful ex vivo multiorgan perfusion was possible following the three retrieval techniques tested, with excellent oxygenation over a 2‐h assessment period, identical to prior studies where the lungs were tested alone. Multiorgan DCD retrieval, including lungs of good quality, is possible from a variety of clinical scenarios and should therefore be considered with all DCD retrieval opportunities.
POTENTIAL FOR CONTAMINATION OF ORTHOPAEDIC IMPLANTS USING INDIVIDUALLY WRAPPED SCREWS
Authors: Crick Brad , Chua Soong , Canty James , McCullough Keith
Published: March 2008

Background:  There has been an anecdotal shift away from screw banks in orthopaedic surgery in preference for individually wrapped screws. Our hypothesis is that opening individually wrapped items introduces a possible source of contamination of the surgical set‐up and repeated opening compounds this potential. Theoretically, this could pose a greater infection risk to the patient than the alternative of a screw bank.

Methods:  One hundred screws were double wrapped in an identical fashion to the standard practice at our hospital. We used Glitterbug (Glitterbug cream is a commercially available product available from Brevis Corporation, Salt Lake City, Utah, USA) cream, which is designed to be near invisible to the naked eye but visible under ultraviolet light. After bathing their hands in the cream, 5 theatre nurses opened 20 screws as if being carried out during an operation. Ultraviolet light was used to evaluate transfer of the cream. Samples were considered positive if there was any evidence of fluorescence under ultraviolet light. Five screw banks were also opened and inspected using the same methods for comparison.

Results:  We identified contamination in one of the 100 screws. No contamination of the inner packaging of the screw banks was observed. At no stage did any participants believe that contamination had occurred.

Conclusions:  This study has shown that the opening of individually wrapped items increases the risk for potential contamination of an operative field, suggesting that the move towards using individually wrapped components for surgery warrants further investigation. We believe that orthopaedic operating theatres should consider the use of screw banks to minimize the risk of contamination.
CLINICAL IMPACT OF ONCOPLASTIC SURGERY IN A SPECIALIST BREAST PRACTICE
Authors: Kollias James , Davies Giles , Bochner Melissa A. , Gill Peter G.
Published: March 2008

Background:  Oncoplastic breast surgery is an integral and fundamental component of the clinical management of breast cancer. The aim of this study was to determine the proportion of oncoplastic and reconstructive breast cancer procedures undertaken within a specialist breast practice.

Methods:  An audit of breast‐related cancer procedures was undertaken for patients with early breast cancer between 1 January 2001 and 31 December 2005, treated at the Royal Adelaide Hospital and in private practice. The proportion of oncoplastic and breast reconstructive procedures was calculated to determine the clinical effects on a specialist breast‐surgical practice.

Results:  Breast cancer resection procedures accounted for 1514 of 2113 of operations (72%). Most of these (897 of 1514, 59.2%) were wide local excision or re‐excision procedures. Total breast reconstruction operations (i.e. autogenous tissue flaps, tissue expander/implant reconstructions) accounted for 251 procedures. Of these, 67 (26.7%) were carried out at the time of simple mastectomy. Contralateral breast procedures (i.e. reduction mammaplasty, mastopexy and augmentation) accounted for 138 procedures and nipple–areola reconstruction/tattoo accounted for 153 procedures. Oncoplastic procedures, such as skin‐sparing mastectomy, latissimus dorsi miniflap and therapeutic mammaplasty accounted for 57 of 599 procedures (9.5%). Breast reconstruction and oncoplastic operations accounted for 599 of 2113 procedures (28%).

Conclusion:  Specialist breast surgeons trained in breast reconstruction and oncoplastic techniques can expect a substantial proportion of their breast practice to include such operative procedures (28% in this series). Subspecialist training in breast surgery should incorporate experience in breast reconstructive and aesthetic surgery for trainees who wish to practise as specialist breast surgeons in the future.
Peer Deviancy Training and Peer Coercion: Dual Processes Associated With Early‐Onset Conduct Problems
Authors: Snyder James , Schrepferman Lynn , McEachern Amber , Barner Stacy , Johnson Kassy , Provines Jessica
Published: March 2008

The prospective relationships of conduct problems and peer coercion and deviancy training during kindergarten (mean age = 5.3 years) to overt and covert conduct problems in third–fourth grade were examined in a sample of 267 boys and girls. Coercion and deviancy training were distinct peer processes. Both were associated with earlier child conduct problems but were differentially associated with child impulsivity, verbal ability, anxiety, peer rejection, and deviant peer affiliation. Coercion by peers predicted overt conduct problems and peer deviancy training and the interaction of deviancy training and coercion predicted covert conduct problems in third–fourth grade. Peer deviancy training occurs in early childhood and may serve as an independent risk mechanism in addition to peer coercion for early‐onset, persisting conduct problems.
Stepping Stones to Others’ Minds: Maternal Talk Relates to Child Mental State Language and Emotion Understanding at 15, 24, and 33 Months
Authors: Taumoepeau Mele , Ruffman Ted
Published: March 2008

This continuation of a previous study (Taumoepeau & Ruffman, 2006) examined the longitudinal relation between maternal mental state talk to 15‐ and 24‐month‐olds and their later mental state language and emotion understanding (N= 74). The previous study found that maternal talk about the child’s desires to 15‐month‐old children uniquely predicted children’s mental state language and emotion task performance at 24 months. In the present study, at 24 months of age, mothers’ reference to others’ thoughts and knowledge was the most consistent predictor of children’s later mental state language at 33 months. Vygotsky’s zone of proximal development provides a framework within which maternal talk, first, about the child’s desires and then about others’ thoughts and knowledge scaffolds children’s social understanding.
The Interplay of Social Competence and Psychopathology Over 20 Years: Testing Transactional and Cascade Models
Authors: Burt Keith B. , Obradović Jelena , Long Jeffrey D. , Masten Ann S.
Published: March 2008

Associations among internalizing, externalizing, and social competence were examined in a longitudinal cohort (N = 205) of 8‐ to 12‐year‐old children reassessed after 7, 10, and 20 years. Theoretically informed nested structural equation models tested interconnections among broad multi‐informant constructs across four developmental periods. Follow‐up analyses examined gender invariance, measurement and age effects, and putative common causes. Key model comparisons indicated robust negative paths from social competence to internalizing problems from childhood to adolescence and from emerging adulthood to young adulthood. Social competence and externalizing problems showed strong initial associations in childhood but no longitudinal cross‐domain paths. Using a developmental psychopathology framework, results are discussed in relation to cascade and transactional effects and the interplay between competence and symptoms over time.
Judicious Imitation: Children Differentially Imitate Deterministically and Probabilistically Effective Actions
Authors: Schulz Laura E. , Hooppell Catherine , Jenkins Adrianna C.
Published: March 2008

Three studies look at whether the assumption of causal determinism (the assumption that all else being equal, causes generate effects deterministically) affects children’s imitation of modeled actions. These studies show even when the frequency of an effect is matched, both preschoolers (N= 60;M= 56 months) and toddlers (N= 48;M= 18 months) imitate actions more faithfully when modeled actions are deterministically rather than probabilistically effective. A third study suggests that preschoolers’ (N= 32;M= 58 months) imitation is affected not just by whether the agent’s goal is satisfied but also by whether the action is a reliable means to the goal. Children’s tendency to generate variable responses to probabilistically effective modeled actions could support causal learning.