bluuebunny/crossref_metadata_2025 huggingface dataset:
Image forces of screw dislocations in a magnetoelectroelastic layered half-plane
Authors: Ma Chien-Ching , Lee Jui-Mu
Published: June 2007

The two-dimensional analysis of elastic, electric, and magnetic fields induced by generalized screw dislocations embedded in a transversely isotropic magnetoelectroelastic layered half-plane is presented in this study. The results indicate that explicit solutions for this problem consist only of the simplest solutions for an infinite magnetoelectroelastic medium with a generalized screw dislocation. It is shown that the physical meaning of the solution is the image method. The mathematical method used in this study provides an automatic determination for the locations and magnitudes of image screw dislocations. From the generalized Peach-Koehler equation, the explicit forms of image forces exerted on a generalized screw dislocation in a layered half-plane are derived from the full-field solutions of the generalized stresses. Numerical results for the full-field distributions of the generalized stresses in the layered half-plane medium are presented. The image forces and equilibrium positions of one screw dislocation, two screw dislocations, and an array of screw dislocations are presented by numerical calculations and are discussed in detail.
O
2
(
Δ
1
)
production in high pressure flowing He∕O2 plasmas: Scaling and quenching
Authors: Babaeva Natalia Y. , Arakoni Ramesh , Kushner Mark J.
Published: June 2007

Chemical oxygen-iodine lasers (COILs) oscillate on the P1∕22→P3∕22 transition of atomic iodine at 1.315μm by a series of excitation transfers from O2(Δ1). In electrically excited COILs (eCOILs), the O2(Δ1) is produced in a flowing plasma, typically He∕O2, at a few to tens of Torr. Many system issues motivate operating eCOILs at higher pressures to obtain larger absolute densities of O2(Δ1) for a given yield and to provide higher back pressure for expansion. In this paper, we discuss results from a computational investigation of O2(Δ1) production in flowing plasmas sustained at moderate pressures (⩽50Torr). Power deposition and flow rates were scaled such that in the absence of second order effects, yield should be constant and absolute O2(Δ1) production should scale linearly with pressure. We found in many cases that absolute O2(Δ1) production scaled sublinearly with pressure. Ozone is found to be one of the major quenchers of O2(Δ1) and its production increases with pressure. Gas heating also increases with increasing pressure due to exothermic three-body reactions. The gas heating reduces O3 production, increases O3 destruction and, for certain conditions, restores yields. With increasing pressure and increasing absolute densities of atomic oxygen and pooling reactions of O2(Δ1), quenching by these species also becomes important, though the influence of O-atom quenching can be controlled by managing the density of O atoms with additives. The yield of O2(Δ1) is also determined by discharge stability which becomes problematic at higher pressure.
Stokes luminescence and frequency upconversion in Pr3+ doped TeO2–PbO glass
Authors: Rai Vineet Kumar , Menezes Leonardo de S. , de Araújo Cid B.
Published: June 2007

Optical properties of Pr3+ doped TeO2–PbO glass were investigated by resonant excitation of H43→D21 transition at ∼586nm. The decay time of D21 level, the energy transfer (ET) rates from the D21 level to other Pr3+ states, and the frequency upconversion process which leads to emission at 484nm (P03→H43 transition) were studied. The ET rates between Pr3+ ions were determined and their interaction was identified as due to dipole-dipole potential. A model used to describe the emission P03→H43 provided information on the dynamics of Pr3+ pair states. The upconversion ET rate was also determined.
Comment on “Theory of the photodissociation of ozone in the Hartley continuum: Potential energy surfaces, conical intersections, and photodissociation dynamics” [J. Chem. Phys. 123, 014306 (2005)]
Authors: Grebenshchikov S. Yu. , Schinke R.
Published: June 2007

We demonstrate in this Comment that the quantum mechanical absorption spectrum of the Hartley band of ozone, calculated using the diabatic B state potential energy surface constructed from the ab initio data of the title paper, is strongly structured. This result, which is in agreement with previous theoretical studies of the Hartley band, contradicts the findings of Baloïtcha and Balint-Kurti and questions the accuracy of their calculations.
Multilevel dendritic structure with simultaneously negative permeability and permittivity
Authors: Yao Y. , Zhao X. P.
Published: June 2007

We study experimentally and numerically the transmission properties of the multilevel dendritic structures. This kind of structure produces one electric resonance and multiple magnetic resonances in different frequencies. In the case of dendritic structure alone, we can tune the magnetic resonance peak into the negative permittivity regime by changing the dimension of dendritic geometry, and achieve a left-handed transmission band. Three-order dendritic structures are fabricated on one side of the dielectric substrate using the lithographic circuit board technique, and the left-handed behavior is observed experimentally between 8 and 12GHz. It is found that the phase of S21 of three-order dendritic structure has a sudden variation at the left-handed pass band. At the same time, the effective permittivity and permeability are simultaneously negative.
Single photon ionization of hydrogen bonded clusters with a soft x-ray laser: (HCOOH)x and (HCOOH)y(H2O)z
Authors: Heinbuch S. , Dong F. , Rocca J. J. , Bernstein E. R.
Published: June 2007

Pure, neutral formic acid (HCOOH)n+1 clusters and mixed (HCOOH)∕(H2O) clusters are investigated employing time of flight mass spectroscopy and single photon ionization at 26.5eV using a very compact, capillary discharge, soft x-ray laser. During the ionization process, neutral clusters suffer little fragmentation because almost all excess energy above the vertical ionization energy is taken away by the photoelectron, leaving only a small part of the photon energy deposited into the (HCOOH)n+1+ cluster. The vertical ionization energy minus the adiabatic ionization energy is enough excess energy in the clusters to surmount the proton transfer energy barrier and induce the reaction (HCOOH)n+1+→(HCOOH)nH++HCOO making the protonated (HCOOH)nH+ series dominant in all data obtained. The distribution of pure (HCOOH)nH+ clusters is dependent on experimental conditions. Under certain conditions, a magic number is found at n=5. Metastable dissociation rate constants of (HCOOH)nH+ are measured in the range (0.1–0.8)×104s−1 for cluster sizes 4<n<9. The rate constants display an odd/even alternating behavior between monomer and dimer loss that can be attributed to the structure of the cluster. When small amounts of water are added to the formic acid, the predominant signals in the mass spectrum are still (HCOOH)nH+ cluster ions. Also observed are the protonated mixed cluster series (HCOOH)n(H2O)mH+ for n=1–8 and m=0–4. A magic number in the cluster series n=5, m=1 is observed. The mechanisms and dynamics of formation of these neutral and ionic clusters are discussed.
Synthesis process controlled magnetic properties of Pb1−xMnxS nanocrystals
Authors: Silva R. S. , Morais P. C. , Qu Fanyao , Alcalde A. M. , Dantas N. O. , Sullasi H. S. L.
Published: June 2007

Mn-doped PbS nanocrystals (NCs) in an oxide glass matrix have been synthesized by the fusion method. Two kinds of Mn2+ sites, located inside and on the surface of NCs, are observed by electron paramagnetic resonance (EPR) spectroscopy in the X band and at room temperature. The proportion of their contribution to the hyperfine structure in the EPR spectrum depends strongly on thermal annealing time. The authors illustrate how thermal annealing process manifests itself in engineering the magnetic properties of NCs.
Polymeric nanocomposite infrared photovoltaics enhanced by pentacene
Authors: Thapa Ram , Roy Choudhury Kaushik , Kim Won Jin , Sahoo Yudhisthira , Cartwright A. N. , Prasad Paras N.
Published: June 2007

An infrared active thin film polymeric photovoltaic device is fabricated from regioregular poly(3-hexylthiophene), PbSe quantum dots, and the organic semiconductor pentacene. The PbSe quantum dots are infrared photosensitizers. Pentacene is incorporated into the formulation in a soluble precursor form. The current-voltage measurements of the device show that the photovoltaic performance is significantly increased by the introduction of pentacene, with both short-circuit current density and open-circuit voltage increased by a factor of 2. The improved performance of the device is attributed to the high mobility of charge carriers in pentacene probably due to conducting domains provided by it.
Experimental investigation of dynamic effects in a two-bar/three-point bend fracture test
Authors: Jiang Fengchun , Vecchio Kenneth S.
Published: June 2007

A Hopkinson pressure bar has been modified to measure the dynamic fracture properties of materials at loading rates greater than ∼106MPam∕s. Some fundamental dynamic effects associated with the incident stress pulse, such as stress wave propagation characteristics along the Hopkinson bar and within the cracked specimen, the specimen’s dynamic response excited by the stress pulse, and the specimen contact situations with the impactor and supports, need to be understood. To better comprehend these fundamental issues, an experimental investigation of these dynamic effects with the emphasis on “loss of contact” was first performed on a two-bar/three-point dynamic bend fracture test setup using a voltage measurement circuit across the specimen/loading-pin interfaces and high-speed photographs. It was demonstrated here that the three-point bend specimen employed with the current two-bar/three-point bend test setup remains in contact with the impactor and supports throughout the first loading duration and that “loss of contact” does not occur. A further improvement using a pulse-shaping technique was employed for achieving a tailored incident pulse. The effect of pulse shaper on the rise time and duration of the incident pulse as well as the dynamic stress equilibrium in the cracked three-point bend has been investigated, for the first time here, with profound implications for significantly improved dynamic three-point bend fracture testing.
Stress dependence of the Raman spectrum of polycrystalline barium titanate in presence of localized domain texture
Authors: Sakashita Tatsuo , Deluca Marco , Yamamoto Shinsuke , Chazono Hirokazu , Pezzotti Giuseppe
Published: June 2007

The stress dependence of the Raman spectrum of polycrystalline barium titanate (BaTiO3, BT) ceramics has been examined with microprobe polarized Raman spectroscopy. The angular dependence of the Raman spectrum of the tetragonal BT crystal has been theoretically established, enabling us to assess the stress dependence of selected spectral modes without the influence of crystallographic domain orientation. Upon considering the frequency shift of selected Raman modes as a function of orientation between the crystallographic axis and the polarization vector of incident and scattered light, a suitable instrumental configuration has been selected, which allowed a direct residual stress measurement according to a modified piezospectroscopic procedure. The analysis is based on the selection of mixed photostimulated spectral modes in two perpendicular angular orientations.
Phonon assisted thermophoretic motion of gold nanoparticles inside carbon nanotubes
Authors: Schoen Philipp A. E. , Walther Jens H. , Poulikakos Dimos , Koumoutsakos Petros
Published: June 2007

The authors investigate the thermally driven mass transport of gold nanoparticles confined inside carbon nanotubes using molecular dynamics simulations. The observed thermophoretic motion of the gold nanoparticles correlates with the phonon dispersion exhibited by a standard carbon nanotube and, in particular, with the breathing mode of the tube. Additionally, the results show an increased static friction for gold nanoparticles confines inside a zig-zag carbon nanotube when increasing the size (length) of the nanoparticles. However, an unexpected, opposite trend is observed for the same nanoparticles inside armchair tubes.
Epitaxial growth of MgO nanowires by pulsed laser deposition
Authors: Nagashima Kazuki , Yanagida Takeshi , Tanaka Hidekazu , Kawai Tomoji
Published: June 2007

We fabricated single-crystalline MgO nanowires epitaxially grown on MgO single crystal substrate using the Au catalyst-assisted pulsed laser deposition (PLD). Controlling appropriately the amount of Au catalyst and the substrate temperature was found to be crucial for the MgO nanowire growth using the catalyst-assisted PLD. In addition, (100) oriented MgO nanowires were epitaxially grown on (100), (110), and (111) oriented substrates, allowing the limited growth directions. The possible growth mechanism of MgO nanowires in PLD is discussed. This feasibility of PLD for fabricating MgO nanowires would contribute to incorporating the rich functionalities of various transition metal oxides into nanowires via in situ construction of heterostructures in oxide nanowires.
W
O
3
nanofibers for gas sensing applications
Authors: Piperno S. , Passacantando M. , Santucci S. , Lozzi L. , La Rosa S.
Published: June 2007

W O 3 nanofibers (NFs), with diameter of about 150–200nm, were grown using the electrospinning technique starting from WCl6 as tungsten source. The NFs were deposited onto a patterned substrate, for gas sensing measurements, and on a silicon substrate, for chemical and structural characterizations. The chemical composition of the NFs was determined by the x-ray photoemission spectroscopy, while high spatial resolution soft x-ray photoemission spectroscopy showed a chemical image of the NF. The gas sensing properties of these NFs were checked towards NO2 and CO, showing a good response for NO2 while no effect was observed for CO.
Experimental and theoretical studies of particle generation after laser ablation of copper with a background gas at atmospheric pressure
Authors: Wen Sy-Bor , Mao Xianglei , Greif Ralph , Russo Richard E.
Published: June 2007

Laser ablation has proven to be an effective method for generating nanoparticles; particles are produced in the laser induced vapor plume during the cooling stage. To understand the in situ condensation process, a series of time resolved light scattering images was recorded and analyzed. Significant changes in the condensation rate and the shape of the condensed aerosol plume were observed in two background gases, helium and argon. The primary particle shape and size distributions were measured using a transmission electron microscope, a scanning electron microscope, and a differential mobility analyzer. The gas dynamics simulation included nucleation and coagulation within the vapor plume, heat and mass transfer from the vapor plume to the background gas, and heat transfer to the sample. The experimental data and the calculated evolution of the shape of the vapor plume showed the same trend for the spatial distribution of the condensed particles in both background gases. The simulated particle size distribution also qualitatively agreed with the experimental data. It was determined that the laser energy, the physical properties of the background gas (conductivity, diffusivity, and viscosity), and the shape of the ablation system (ablation chamber and the layout of the sample) have strong effects on the condensation process and the subsequent sizes, shapes, and degree of aggregation of the particles.
Strong magnetoelectric charge coupling in stress-biased multilayer-piezoelectric∕magnetostrictive composites
Authors: Dong Shuxiang , Zhai Junyi , Li Jie-Fang , Viehland D. , Summers Eric
Published: June 2007

A magnetoelectric composite consisting of a multilayer Pb(Zr,Ti)O3 piezoelectric (d33) stack and a magnetostrictive (Galfenol and∕or Terfenol-D) rod assembled in a prestressed frame in a longitudinal-longitudinal configuration has been found to have a high magnetoelectric (ME) charge coupling to an applied magnetic field. Values of the ME charge coefficient as high as 16.4nC∕Oe (or 3.6×10−6C∕m2Oe) were found at quasistatic frequencies and 123nC∕Oe (or 2.8×10−5C∕m2Oe) under resonance drive, which are 100–1000 times higher than that previously reported for other ME laminates.
Magnetic properties and enhanced magnetic refrigeration in (Mn1−xFex)5Ge3 compounds
Authors: Zhang Q. , Du J. , Li Y. B. , Sun N. K. , Cui W. B. , Li D. , Zhang Z. D.
Published: June 2007

Magnetic and magnetocaloric effects of (Mn1−xFex)5Ge3 compounds are studied systematically. The maximum of magnetic entropy changes of 8.01 J/kg K under an external field change of 5 T is obtained for (Mn0.9Fe0.1)5Ge3, which is the largest value in Mn5Ge3-based solid solutions. Moreover, the Fe substitution increases the refrigeration capacity (RC) value greatly. The largest RC value of 237 J/kg in (Mn0.8Fe0.2)5Ge3 even compares favorably to that of many well-known magnetic refrigeration materials. Thus the Fe-containing (Mn1−xFex)5Ge3 compounds are much-improved magnetic refrigerants for the application of room-temperature magnetic refrigeration. The increase of the RC value is probably resulted from the formation of magnetic nanostructure.
Griffiths phase and magnetic polaronic behavior in B-site disordering manganites
Authors: Fan Jiyu , Pi Li , He Yan , Ling Langsheng , Dai Jixia , Zhang Yuheng
Published: June 2007

We report a detailed study of magnetic and transport properties in perovskite manganites Nd0.55Sr0.45Mn1−xGaxO3 (0.00⩽x⩽0.20). The Ga substitution induces the B-site disorder together with a distinct suppression of the metal-insulator transition and ferromagnetic-paramagnetic transition. Due to an appearance of inhomogeneous magnetic clusters, the Griffiths-like phase is observed in 0.08⩽x⩽0.10 compounds. Meanwhile, with the increase of Ga concentration, the carriers self-trap into magnetic polarons. Because the oxygen sublattice distortion causes the variation of the phonon density of state, an additional Raman vibrative mode appears in the system.
Influence of polymer gate dielectrics on n-channel conduction of pentacene-based organic field-effect transistors
Authors: Guo Tzung-Fang , Tsai Zen-Jay , Chen Shi-Yu , Wen Ten-Chin , Chung Chia-Tin
Published: June 2007

This work elucidates the way polymer gate dielectrics affect the accumulation and transport of charge carriers in the active layer of organic field-effect transistors (OFETs). Incorporating a poly(vinyl alcohol) polymer interfacial film and another cross-linked poly(4-vinyl phenol) layer as a double-layer gate dielectric causes the pentacene-based OFETs to exhibit effective n-channel conduction of a saturated, apparent pinch-off drain-source current with the electron mobility of ∼0.012cm2V−1s−1. The formation of an n channel in the pentacene layer is supported by the increased capacitance that is identified by the quasistatic capacitance-voltage measurements of devices with the metal-insulator-semiconductor configuration, biased at a positive gate voltage, in the n-type accumulation regime.
Structural, magnetic, and transport properties of nanoparticles of the manganite Pr0.5Ca0.5MnO3
Authors: Sarkar Tapati , Mukhopadhyay P. K. , Raychaudhuri A. K. , Banerjee Sangam
Published: June 2007

In this paper we report the structural, magnetic, and transport properties of nanoparticles of Pr0.5Ca0.5MnO3(PCMO). On comparing our results with that of bulk PCMO, we find that there is a likely destabilization of charge ordering in nanoparticles of PCMO. The investigation has been done with particle sizes as small as 15nm synthesized by polyol route. The size reduction (by keeping the chemical composition unchanged) reduces the orthorhombic c axis preferentially and thus reduces the orthorhombic distortion. The size reduction to 15nm enhances the ferromagnetic moment at low temperatures and strongly suppresses the activated charge transport which is seen in the bulk samples of charge ordered PCMO.
Pairing of cation vacancies and gap-state creation in TiO2 and HfO2
Authors: Ahn Hyo-Shin , Han Seungwu , Hwang Cheol Seong
Published: June 2007

Based on the first-principles calculations, the authors study defect-defect interactions between cation vacancies in rutile TiO2 and monoclinic HfO2. It is found that vacancies are greatly stabilized at small separations because of a large reconstruction of nearby oxygen atoms that have two broken bonds. As a result, O–O bonds resembling O2 or O3 molecules are formed near the divacancy site. The defect levels originated from antibonding states of O p orbitals are identified within the energy gap, which can affect leakage currents and the density of trapped charges of oxides substantially.
In situ Ni–Si nanowire junction based on substrate sourced growth and its electrical transport behavior
Authors: Lee Yun-Hi , Kwon Hyuk-Sang
Published: June 2007

The authors report on formation of high current carrying Ni–Si nanowires between Ni/heavily doped polycrstaliine Si contacts using substrate sourced growth without any supply of Si source gas. The conductance (G) of a 18nm diameter nanowire bridge in the temperature range of 13–293K showed a power function of temperature Tα, with a typical exponent α≈0.62±0.06, and the dI∕dV were fitted to the Vα with α≈0.55±0.15. Although the power law dependence of the G and dI∕dV, which provides evidence for the interaction of the electrons in a low-dimensional infinite conductor, corresponds to the featured behavior of the interacting electrons within an error tolerance, the strength of the interaction is very weak due to the highly metallic characteristics with finite length and lack of purity of the channel. As a result, the in situ high current carrying Ni-Si nanowire junction can be utilized not only as a nanointerconnector, but also as a tool to study low-dimensional electrical transport properties.
Surface-plasmon-enhanced transmission through metallic film perforated with fractal-featured aperture array
Authors: Bao Yong-Jun , Zhang Bo , Wu Zhe , Si Jian-Wen , Wang Mu , Peng Ru-Wen , Lu Xiang , Shao Jun , Li Zhi-feng , Hao Xi-Ping , Ming Nai-Ben
Published: June 2007

A fractal-featured metallic thin film with Sierpinski Carpet pattern is fabricated on silicon wafer by microfabrication techniques. Transmission infrared spectroscopy indicates that there exists extraordinary high transmission at specific wavelengths, which can be ascribed to the effect of surface plasmon resonance, and are determined by hierarchy of apertures of different sizes in the fractal structure. This patterned film provides a unique system to achieve enhanced transmission simultaneously at different selected frequencies of electromagnetic wave.
Factors limiting the operation frequency of magnetic refrigerators
Authors: Kuz’min M. D.
Published: June 2007

Simple calculations lead to a conclusion that there is an upper bound to the frequency at which magnetic refrigerators can operate, fmax∼2×102Hz. The principal factor limiting the operation frequency is a trade-off between thermal conductivity and viscous friction. The main events take place inside the magnetocaloric bed—the fundamental unit of any magnetic refrigerator—largely independently from the rest of the apparatus.
Element specific investigations of the structural and magnetic properties of Gd:GaN
Authors: Ney A. , Kammermeier T. , Manuel E. , Ney V. , Dhar S. , Ploog K. H. , Wilhelm F. , Rogalev A.
Published: June 2007

The authors present element specific measurements of the x-ray linear dichroism and the x-ray magnetic circular dichroism (XMCD) on Gd:GaN samples. They can show that the majority of the Gd dopant atoms goes to substitutional Ga sites and that a small XMCD is detectable for Gd. There are significant deviations of the magnetic hysteresis recorded for Gd compared to superconducting quantum interference device measurements. Our measurements show that the magnetic signal from the Gd dopant atom itself is rather small highlighting the role of magnetic contributions of the GaN host crystal.
Electrowetting manipulation of any optical film
Authors: Hou L. , Smith N. R. , Heikenfeld J.
Published: June 2007

Electrowetting manipulation of any optical film is reported. A square channel was constructed with four sidewall electrodes, coated with a hydrophobic dielectric, and filled with saline and oil. In a first experiment a dielectric mirror film was suspended between the oil/saline meniscus. Electrowetting at each sidewall produced a saline contact angle change of 35°<θ<170°. This change in contact angle tilted the mirror and ±105° of laser beam deflection was achieved. A second experiment utilized a Mylar film imprinted with a diffraction grating (625lines∕mm). Electrowetting tilting of the grating was shown to alter the diffraction of the laser beam.
347
nm
ultraviolet electroluminescence from MgxZn1−xO-based light emitting devices
Authors: Chen Peiliang , Ma Xiangyang , Li Dongsheng , Zhang Yuanyuan , Yang Deren
Published: June 2007

347 nm ultraviolet (UV) electroluminescence (EL) originated from the near-band-edge emission of MgxZn1−xO was realized on a MgxZn1−xO-based metal-insulator (SiO2)-semiconductor (MIS) structure on a silicon substrate. Compared with the EL performance of the MgxZn1−xO∕n+-Si heterojunction, the MgxZn1−xO-based MIS structure exhibited much stronger and purer UV emission while much weaker visible emissions. This is ascribed to the carrier accumulation beneath the MgxZn1−xO∕SiO2 interface as the MIS structure is under forward bias, which significantly increases the radiative interband recombination rate and therefore the UV emission from MgxZn1−xO.
Imaging of thermal domains in ultrathin NbN films for hot electron bolometers
Authors: Doenitz D. , Kleiner R. , Koelle D. , Scherer T. , Schuster K. F.
Published: June 2007

The authors present low-temperature scanning electron microscopy (LTSEM) investigations of superconducting microbridges made from ultrathin NbN films as used for hot electron bolometers. LTSEM probes the thermal structure within the microbridges under various dc bias conditions, either via electron-beam-induced generation of an unstable hot spot or via the beam-induced growth of a stable hot spot. Such measurements reveal inhomogeneities on a micron scale, which may be due to spatial variations in the NbN film or film-interface properties. Comparison with model calculations for the stable hot spot regime confirms the basic features of common hot spot models.
Magneto-optical techniques to determine Curie temperature of magnetic fluids
Authors: Patel Rajesh , Raval Alpesh
Published: June 2007

Magnetic field induced extinction of light and birefringence as a function of temperature is used to study the temperature dependence of magnetic moment as well as the domain magnetization of the temperature sensitive magnetic fluids. Subsequently, the Curie temperature and pyromagnetic coefficient of the same are determined. The results obtained from this technique are compared with the results obtained from other techniques. This technique is remarkably simple and low cost.
Giant magnetostriction in Sm1−xNdxFe1.93 compounds
Authors: Hari Babu V. , Markandeyulu G. , Subrahmanyam A.
Published: June 2007

The polycrystalline Sm1−xNdxFe1.93 (x=0, 0.08, 0.12, 0.16, 0.2, 0.24, 0.32, and 0.36) compounds are found to stabilize in MgCu2-type C15 cubic Laves phase structure. The compound x=0.12 is found to exhibit giant magnetostriction value of −1572×10−6 due to the anisotropy compensation between Sm3+ and Nd3+ ions. The easy direction of magnetization (EMD) is observed towards ⟨111⟩ for the 0⩽x⩽0.20 compounds, accompanied by a rhombohedral distortion. For the x=0.32 compound, an orthorhombic distortion, with a support that the EMD is towards ⟨110⟩, is observed.
Phase diagrams of single-domain ferroelectric-dielectric superlattices
Authors: Urtiev F. A. , Kukhar V. G. , Pertsev N. A.
Published: June 2007

Using the thermodynamic theory, the authors developed misfit strain-temperature phase diagrams of single-domain ferroelectric-dielectric superlattices grown on cubic substrates. Owing to internal electric fields appearing in such multilayers, the superlattice diagrams are expected to be very different from phase maps of homogeneous ferroelectric films. The calculations show, however, that this electrostatic effect does not change relative positions of phase transition lines. It only shifts the diagram as a whole along the line separating stability ranges of paraelectric phase and in-plane polarization state. The magnitude of this shift is governed by the capacitance of dielectric layer and the thickness of ferroelectric one.
Flux chamber study of particle formation from Durvillaea potatorum
Authors: Cainey Jill M. , Keywood Melita , Bigg E. Keith , Grose Michael R. , Gillett Rob W. , Meyer Mick
Published: June 2007

Environmental context. Kelp at Mace Head, Ireland, produces large quantities of iodine when exposed to sunlight at low tide and this iodine results in the rapid production of particles. Cape Grim, Tasmania, also has large colonies of kelp (Durvillaea potatorum) but its role in particle formation appears limited. A flux chamber was used to better understand the response of Durvillaea potatorum to light stress and ozone.
Abstract. Brown kelp, in particular Laminara digitata at Mace Head, Ireland, has been shown to emit iodine when under stress, resulting in new particle formation. The Cape Grim Baseline Air Pollution Station, Tasmania, is surrounded by rocky reefs that support large colonies of the brown kelp Durvillaea potatorum. During an intensive campaign in February 2006 at Cape Grim, levels of IO, OIO and methyl iodide remained at background levels and no particle formation events could be associated with locally generated precursor iodine species.
In order to better understand the limitations of the local kelp to provide a source of precursor species, samples of Durvillaea potatorum were collected from the beach below the Cape Grim Station and tested for their capacity to initiate particle formation using a flux chamber technique. Particles were observed only when the kelp was exposed to both very high levels (>100 ppb) of ozone and natural solar radiation. There was a high correlation between ozone level and particles produced. The particles resulting from exposure to high levels of ozone were aromatic and volatile.
Durvillaea potatorum appears to plays a very limited role in contributing to particle formation at Cape Grim, but it does represent a source of atmospheric iodine under photo-oxidative stress, of 18 pmol g–1 (fresh weight) min–1 and is likely to have a significant role in atmospheric chemistry at this site.
A double-blind randomized placebo-controlled phase III study of a
Pseudomonas aeruginosa
flagella vaccine in cystic fibrosis patients
Authors: Döring Gerd , Meisner Christoph , Stern Martin ,   for the Flagella Vaccine Trial Study Group
Published: June 2007

Pseudomonas aeruginosa
causes life-threatening lung infections in patients with cystic fibrosis. We hypothesized that vaccination may prevent
P. aeruginosa
lung infection. In a double-blind, placebo-controlled, multicenter trial, 483 European patients, 2–18 years of age without
P. aeruginosa
colonization were randomly assigned to receive four intramuscular injections of a bivalent
P. aeruginosa
flagella vaccine or placebo over a 14-month period. Patients were evaluated quarterly for
P. aeruginosa
-positive throat cultures and antipseudomonal serum antibody titers during the study period of 2 years. The vaccine was well tolerated, and the patients developed high and long-lasting serum antiflagella IgG titers. In the intention-to-treat group (all patients enrolled), 82 of 239 vaccinated patients had
P. aeruginosa
infection and/or antipseudomonal serum titers compared with 105 of 244 patients in the placebo group (
P
= 0.05; relative risk: 0.80; 95% CI: 0.64–1.00). Analysis of the 381 patients in the per-protocol group, who received all four vaccinations or placebo treatments, revealed 37 of 189 patients with infection episodes in the vaccine group compared with 59 of 192 patients with such episodes in the placebo group (
P
= 0.02; relative risk: 0.66; 95% CI: 0.46–0.93).
P. aeruginosa
strains, exhibiting flagella subtypes included in the vaccine, were significantly less frequently isolated from vaccinates than from placebo controls (
P
= 0.016, relative risk: 0.319; 95% CI: 0.12–0.86). Chronic
P. aeruginosa
infection was rare because of recent institution of early antibiotic eradication regimes. Active immunization of patients with cystic fibrosis lowers the risk for infection with
P. aeruginosa
and therefore may contribute to a longer survival of these patients.
T cell-specific deletion of the inositol phosphatase SHIP reveals its role in regulating Th1/Th2 and cytotoxic responses
Authors: Tarasenko Tatyana , Kole Hemanta K. , Chi Anthony W. , Mentink-Kane Margaret M. , Wynn Thomas A. , Bolland Silvia
Published: June 2007

The 5′-phosphoinositol phosphatase SHIP negatively regulates signaling pathways triggered by antigen, cytokine and Fc receptors in both lymphocytes and myeloid cells. Mice with germ-line (null) deletion of SHIP develop a myeloproliferative-like syndrome that causes early lethality. Lymphocyte anomalies have been observed in SHIP-null mice, but it is unclear whether they are due to an intrinsic requirement of SHIP in these cells or a consequence of the severe myeloid pathology. To precisely address the function of SHIP in T cells, we have generated mice with T cell-specific deletion of SHIP. In the absence of SHIP, we found no differences in thymic selection or in the activation state and numbers of regulatory T cells in the periphery. In contrast, SHIP-deficient T cells do not skew efficiently to Th2in vitro. Mice with T cell-specific deletion of SHIP show poor antibody responses on Alum/NP-CGG immunization and diminished Th2 cytokine production when challenged withSchistosoma mansonieggs. The failure to skew to Th2 responses may be the consequence of increased basal levels of the Th1-associated transcriptional factor T-bet, resulting from enhanced sensitivity to cytokine-mediated T-bet induction. SHIP-deficient CD8+cells show enhanced cytotoxic responses, consistent with elevated T-bet levels in these cells. Overall our experiments indicate that in T cells SHIP negatively regulates cytokine-mediated activation in a way that allows effective Th2 responses and limits T cell cytotoxicity.
Cancellation and stable rank for direct limits of recursive subhomogeneous algebras
Authors: Phillips N.
Published: June 2007

We prove the following results for a unital simple direct limit

A
A

of recursive subhomogeneous algebras with no dimension growth: (1)

tsr
⁡
(
A
)
=
1.

\operatorname {tsr}(A) = 1.

(2) The projections in

M

∞

(
A
)

M_{\infty }(A)

satisfy cancellation: if

e
⊕
q
∼
f
⊕
q
,

e \oplus q \sim f \oplus q,

then

e
∼
f
.

e \sim f.

(3)

A
A

satisfies Blackadar’s Second Fundamental Comparability Question: if

p
,

q
∈

M

∞

(
A
)

p, \, q \in M_{\infty }(A)

are projections such that

τ
(
p
)
>
τ
(
q
)

\tau (p) > \tau (q)

for all normalized traces

τ
\tau

on

A
,

A,

then

p
≾
q
.

p \precsim q.

(4)

K
0

(
A
)

K_0 (A)

is unperforated for the strict order: if

η
∈

K
0

(
A
)

\eta \in K_0 (A)

and there is

n
>
0

n > 0

such that

n
η
>
0
,

n \eta > 0,

then

η
>
0.

\eta > 0.

The last three of these results hold under certain weaker dimension growth conditions and without assuming simplicity. We use these results to obtain previously unknown information on the ordered K-theory of the crossed product

C
∗

(

Z

,
X
,
h
)

C^* (\mathbf {Z}, X, h)

obtained from a minimal homeomorphism of a finite-dimensional infinite compact metric space

X
.

X.

Specifically,

K
0

(

C
∗

(

Z

,
X
,
h
)
)

K_0 (C^* (\mathbf {Z}, X, h))

is unperforated for the strict order, and satisfies the following K-theoretic version of Blackadar’s Second Fundamental Comparability Question: if

η
∈

K
0

(
A
)

\eta \in K_0 (A)

satisfies

τ
∗

(
η
)
>
0

\tau _* (\eta ) > 0

for all normalized traces

τ
\tau

on

A
,

A,

then there is a projection

p
∈

M

∞

(
A
)

p \in M_{\infty } (A)

such that

η
=
[
p
]
.

\eta = [p].
Poisson PI algebras
Authors: Mishchenko S. , Petrogradsky V. , Regev A.
Published: June 2007

We study Poisson algebras satisfying polynomial identities. In particular, such algebras satisfy “customary” identities (Farkas, 1998, 1999) Our main result is that the growth of the corresponding codimensions of a Poisson algebra with a nontrivial identity is exponential, with an integer exponent. We apply this result to prove that the tensor product of Poisson PI algebras is a PI-algebra. We also determine the growth of the Poisson-Grassmann algebra and of the Hamiltonian algebrasH2k\mathbf {H}_{2k}.
Generalizations of Chebyshev polynomials and polynomial mappings
Authors: Chen Yang , Griffin James , Ismail Mourad
Published: June 2007

In this paper we show how polynomial mappings of degree

K

\mathfrak {K}

from a union of disjoint intervals onto

[
−
1
,
1
]

[-1,1]

generate a countable number of special cases of generalizations of Chebyshev polynomials. We also derive a new expression for these generalized Chebyshev polynomials for any genus

g
g

, from which the coefficients of

x
n

x^n

can be found explicitly in terms of the branch points and the recurrence coefficients. We find that this representation is useful for specializing to polynomial mapping cases for small

K

\mathfrak {K}

where we will have explicit expressions for the recurrence coefficients in terms of the branch points. We study in detail certain special cases of the polynomials for small degree mappings and prove a theorem concerning the location of the zeroes of the polynomials. We also derive an explicit expression for the discriminant for the genus 1 case of our Chebyshev polynomials that is valid for any configuration of the branch point.
Embeddability of some strongly pseudoconvex CR manifolds
Authors: Marinescu George , Yeganefar Nader
Published: June 2007

We obtain an embedding theorem for compact strongly pseudoconvex CR manifolds which are boundaries of some complete Hermitian manifolds. We use this to compactify some negatively curved Kähler manifolds with compact strongly pseudoconvex boundary. An embedding theorem for Sasakian manifolds is also derived.
Uniform approximation of eigenvalues in Laguerre and Hermite 𝛽-ensembles by roots of orthogonal polynomials
Authors: Dette Holger , Imhof Lorens
Published: June 2007

We derive strong uniform approximations for the eigenvalues in general Laguerre and Hermite

β
\beta

-ensembles by showing that the maximal discrepancy between the suitably scaled eigenvalues and roots of orthogonal polynomials converges almost surely to zero when the dimension converges to infinity. We also provide estimates of the rate of convergence. In the special case of a normalized real Wishart matrix

W
(

I
n

,
s
)

/

s

W(I_n,s)/s

, where

n
n

denotes the dimension and

s
s

the degrees of freedom, the rate is

(
log
⁡
n

/

s

)

1

/

4

(\log n/s)^{1/4}

, if

n
,
s
→
∞

n,s\to \infty

with

n
≤
s

n\leq s

, and the rate is

log
⁡
n

/

n

\sqrt {\log n/n}

, if

n
,
s
→
∞

n,s\to \infty

with

n
≤
s
≤
n
+
K

n\leq s\leq n+K

. In the latter case we also show the a.s. convergence of the

⌊
n
t
⌋

\lfloor nt \rfloor

largest eigenvalue of

W
(

I
n

,
s
)

/

s

W(I_n,s)/s

to the corresponding quantile of the Marc̆enko-Pastur law.
Limit Weierstrass points on nodal reducible curves
Authors: Esteves Eduardo , Salehyan Parham
Published: June 2007

In the 1980s D. Eisenbud and J. Harris posed the following question: “What are the limits of Weierstrass points in families of curves degenerating to stable curves not of compact type?” In the present article, we give a partial answer to this question. We consider the case where the limit curve has components intersecting at points in general position and where the degeneration occurs along a general direction. For this case we compute the limits of Weierstrass points of any order. However, for the usual Weierstrass points, of order one, we need to suppose that all of the components of the limit curve intersect each other.
The vectorial Ribaucour transformation for submanifolds and applications
Authors: Dajczer M. , Florit L. , Tojeiro R.
Published: June 2007

In this paper we develop the vectorial Ribaucour transformation for Euclidean submanifolds. We prove a general decomposition theorem showing that under appropriate

conditions the composition of two or more vectorial Ribaucour transformations is again a vectorial Ribaucour transformation. An immediate consequence of this result is the classical permutability of Ribaucour transformations. Our main application is to provide an explicit local construction of an arbitrary Euclidean

n
n

-dimensional submanifold with flat normal bundle and codimension

m
m

by means of a commuting family of

m
m

Hessian matrices on an open subset of Euclidean space

R

n

\mathbb {R}^n

. Actually, this is a particular case of a more general result. Namely, we obtain a similar local construction of all Euclidean submanifolds carrying a parallel flat normal subbundle, in particular of all those that carry a parallel normal vector field. Finally, we describe all submanifolds carrying a Dupin principal curvature normal vector field with integrable conullity, a concept that has proven to be crucial in the study of reducibility of Dupin submanifolds.
The class number one problem for the normal CM-fields of degree 32
Authors: Park Sun-Mi , Yang Hee-Sun , Kwon Soun-Hi
Published: June 2007

We prove that there are exactly six normal CM-fields of degree 32 with class number one. Five of them are composita of two normal CM-fields of degree 16 with the same maximal totally real octic field.
Cosmetic Thyroid Surgery: Defining the Essential Principles
Authors: Terris David J. , Seybt Melanie W. , Elchoufi Mayssoun , Chin Edward
Published: June 2007

Objectives: Minimally invasive thyroid surgery is rapidly becoming a common approach in busy endocrine surgery practices. The surgical concepts necessarily include a number of principles found within the realm of plastic surgery.

Design: The study was a prospective, nonrandomized analysis of a consecutive series of thyroid surgical patients.

Methods and Materials: All patients who underwent thyroid surgery at the Medical College of Georgia in the Department of Otolaryngology were prospectively evaluated. Recommendations for endoscopic thyroidectomy, minimally invasive nonendoscopic thyroidectomy (MINET), or conventional thyroid surgery were based on patient and disease parameters as previously described. Specific factors contributing to improved cosmetic outcomes were sought.

Results: Two hundred forty‐eight patients underwent thyroidectomy between September 2003 and June 2006. There were 50 males and 198 females, with a mean age of 44.9 ± 14.6 years. Seventy‐seven (31.0%) patients underwent conventional thyroidectomy (group A), 120 (48.4%) patients had MINET (group B), and the remaining 51 (20.6%) patients underwent thyroidectomy with an endoscopic technique (Group C). Incision lengths were 92.4 ± 22.3 mm in Group A, 46.4 ± 9.9 mm in Group B, and 24.3 ± 5.9 mm in Group C. The factors that contributed most to an optimal cosmetic result were marking the patient while he or she was sitting up prior to surgery, resecting skin edges during closure, avoidance of subplatysmal flap elevation and drains, and use of Dermabond.

Conclusions: Achieving an optimal cosmetic result when performing thyroid surgery is easiest when oneapplies a number of principles, including elements normally associated with plastic surgery.
Long‐Term Improvement of Quality of Life as a Result of Tonsillotomy (With Radiofrequency Technique) and Tonsillectomy in Youths
Authors: Ericsson Elisabeth , Ledin Torbjörn , Hultcrantz Elisabeth
Published: June 2007

Objective: This is a 1 year follow‐up to compare the effects of partial tonsil resection using the radiofrequency technique (RF) tonsillotomy (TT) with total tonsillectomy (TE) (blunt dissection). Obstructive symptoms, tendency for infections, and health‐related quality of life (HRQL) were studied and compared with the HRQL data from a normal population.

Method: The study group consisted of 74 patients (16–25 yr old) randomized to TT (n = 31) or TE (n = 43) with obstructive throat problems with or without recurrent tonsillitis. The Short Form 36 (SF‐36) and EuroQul Visual Analogue Scale were used to evaluate HRQL. A questionnaire investigated the degree of obstruction and history of infections.

Results: Preoperatively, both groups reported significantly lower HRQL in all dimensions of the SF‐36 compared with the normal population (P < .05–P < .001). After 1 year, a large improvement (P < .01–P < .001) in both groups in HRQL was found. No differences were found when these groups were compared with the normal population or between the study groups. The effect on snoring was the same for both groups, and the rate of recurrence of infections was low and not any higher in the TT group.

Conclusion: Preoperative obstructive problems in combination with recurrent tonsillitis have a negative impact on HRQL. Both the TT and TE groups demonstrated large improvements on HRQL, infections, and obstructive problems 1 year after surgery, indicating that the surgical methods are equally effective. With its reduced postoperative complications, less pain, shorter recovery time, and cost reduction, TT with RF should be considered the method of choice.
Structural Variations in a Single Hyaluronan Derivative Significantly Alter Wound‐Healing Effects in the Rabbit Maxillary Sinus
Authors: Orlandi Richard R. , Shu Xiao Zheng , McGill Lawrence , Petersen Everett , Prestwich Glenn D.
Published: June 2007

Background: Biomaterials based on hyaluronan (HA) are currently used after sinus surgery but have not been found to decrease scarring or enhance wound healing. Chemical composition of these modified HA molecules may impact their biological and clinical effects.

Objective: To analyze chemical variations of a single crosslinked HA‐based hydrogel, chemically modified thiolated HA (CMHA‐SX).

Methods: Four different components of the hydrogel composition were altered, yielding 54 variations. These were subjected to biomechanical testing, and then potential clinically relevant variations were further tested for swelling and degradation characteristics. Using a rabbit maxillary sinus model, the ability of the material variations to stent a neo‐ostium was tested. Histologic measures were also assessed. Biomechanical and biological effects were correlated.

Results: Minor compositional changes had profound biomechanical and biological effects. Swelling and rate of enzymatic degradation were closely related. CMHA‐SX hydrogels that were the most effective stents in maintaining the neo‐ostium also generated the lowest level of acute inflammation, as determined by histology.

Conclusions: Chemical composition has a significant impact on the clinical potential of modified HA materials. Histocompatibility appears to most significantly affect ostium preservation.

Significance: Different CMHA‐SX hydrogels perform differently in vivo, even when the chemical compositions are quite similar. Objective prospective testing of modified HA materials should precede their clinical use in sinus surgery.
Thyroid Medullary Carcinoma in a Teenager With Cowden Syndrome
Authors: Koksal Yavuz , Sahin Mustafa , Koksal Hande , Orhan Diclehan , Unal Ekrem , Alagoz Engin
Published: June 2007

Cowden syndrome is a multisystemic cancer predisposition disorder, in which the mucocutaneous lesions are the most constant features. We present a case of Cowden syndrome in a teenage boy with hyperkeratotic papules of the facial skin, especially on the eyelids, with episcleritis, proptosis, and papillomatous lesions on the tip of the tongue and lip mucosa. In addition, two nodules in the thyroid gland were detected. On laboratory examination, the carcinoembryonic antigen (CEA) was 34 ng/mL (normal limits: 0–3 ng/mL). Total thyroidectomy was performed. Histopathologic examination of the specimen revealed thyroid medullary carcinoma. After operation, levels of CEA decreased to normal limits.