bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pulse rate and pulse rate variability decrease after adenotonsillectomy for obstructive sleep apnea
Authors: Constantin Evelyn , McGregor Christine D. , Cote Valerie , Brouillette Robert T. 
Published: March 2008

AbstractBackgroundData suggest that obstructive sleep apnea syndrome (OSA) results in sympathetic stimulation, brady/tachycardia and cardiac stress. Heart rate variability, but not baseline heart rate, is known to be elevated in pediatric OSA. Our patients with moderate to severe OSA (McGill Oximetry Scores of 3 or 4) have been re‐evaluated with pulse oximetry after adenotonsillectomy (T&A). We hypothesized that pulse rate (PR) and pulse rate variability (PRV) would decrease after treatment of OSA with T&A.MethodsThis retrospective before‐after study comprised pre‐ and post‐operative oximetries and parental questionnaires of children 1–18 years old with moderate to severe OSA from September 2004 to August 2005, inclusive. We excluded patients with significant comorbidities.ResultsIn 25 subjects, age at surgery was 4.3 ± 3.6 years (mean ± SD). OSA symptoms decreased or resolved, saturation metrics improved, and parental concern about breathing during sleep decreased following T&A. PR decreased in 21 of 25 patients after T&A (mean PR from 99.7 ± 11.2 to 90.1 ± 10.7 bpm, P < 0.001; maximum PR from 150.6 ± 14.5 to 137.4 ± 15.6 bpm, P < 0.001). PRV, as measured by the standard deviation of the PR, decreased in 23 of 25 patients after T&A (from 10.3 ± 2.1 to 8.2 ± 1.6 bpm, [P < 0.001]). Pulse accelerations greater than 6, 7, 8 bpm also decreased post‐operatively.ConclusionsNocturnal pulse oximetry complements clinical history to document improvement and/or resolution of moderate to severe OSA in children. Resolution of tachycardia and diminished PRV after T&A illustrate the stress that recurrent airway obstruction during sleep places on the cardiovascular system. Further work will be required to determine if PR and PRV as measured by pulse oximetry would be useful in the diagnosis and follow‐up of OSA in children. Pediatr Pulmonol. 2008; 43:498–504. © 2008 Wiley‐Liss, Inc.
Role of the work function of transparent conductive oxide on the performance of amorphous/crystalline silicon heterojunction solar cells studied by computer simulation
Authors: Zhao L. , Zhou C. L. , Li H. L. , Diao H. W. , Wang W. J. 
Published: March 2008

AbstractThe role of the work function of transparent conductive oxide (WTCO) on the performance of amorphous/crystalline silicon heterojunction (SHJ) solar cells was investigated in detail with other various parameters by utilizing AFORS‐HET software as a numerical computer simulation tool. The results for SHJ solar cells based on p‐type and n‐type substrates were demonstrated and analyzed comparatively with or without the insertion of the intrinsic amorphous silicon layer between the doped amorphous emitter and the crystalline base. It was indicated that there was an optimized threshold thickness of the emitter for the solar cells to obtain the best performance for any given WTCO and the doping concentration of the emitter. Thus, design criteria of TCO/emitter for the practical SHJ solar cells were provided. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ferromagnetic resonance force microscopy studies of a continuous permalloy–cobalt film
Authors: Nazaretski E. , Akhadov E. A. , Cha K. C. , Pelekhov D. V. , Martin I. , Graham K. S. , Hammel P. C. , Movshovich R. 
Published: March 2008

AbstractMagnetic resonance force microscopy (MRFM) offers a means of performing local ferromagnetic resonance. We have studied the evolution of the MRFM force spectra in a continuous 20 nm thick cobalt–permalloy film as a function of lateral position. We clearly observed localized resonance signals originating from cobalt and permalloy. The spatial resolution in our experiments was determined to be better than 5 μm thus opening up the possibility to perform localized spectroscopic studies in continuous ferromagnetic samples. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spin‐mixing conductances: The influence of disorder
Authors: Carva Karel , Turek Ilja 
Published: March 2008

AbstractSpin‐transfer torque exerted on a magnetic layer can be viewed as a linear response to the spin accumulation inside an adjacent non‐magnetic layer, information about their response coefficient is provided by the complex spin‐mixing conductance Cmix. Substitutional disorder is known to affect the spin‐dependent charge conductances and often reduces strongly the magnetoresistance. Here we examine its impact on Cmix of several selected realistic systems.Recently predicted oscillations of Cmix as a function of ferromagnetic layer thickness in Ni based junctions might be suppressed by interface interdiffusion, but presented ab initio calculations disprove this possibility. Halfmetallic character of the Heusler compound Co2MnSi is destroyed by often encountered antisite disorder; however the impact of this disorder to the predicted Cmix is rather weak. Diluted magnetic semiconductor (Ga,Mn)As is an intrinsically disordered system, the analysis of calculations shows that the variation of Cmix with substitutional Mn content can be understood in terms of the associated change of the number of carriers, whereas the variation with lattice defects is more complex. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
AlInN/GaN HEMTs on sapphire: dc and pulsed characterisation
Authors: Fieger M. , Eickelkamp M. , Zhang W. , Khoshroo L. Rahimzadeh , Mauder C. , Dikme Y. , Heuken M. , Noculak A. , Kalisch H. , Jansen R. H. , Vescan A. 
Published: March 2008

AbstractLattice‐matched Al0.83In0.17N/GaN high electron mobility transistors (HEMTs) grown by MOCVD on sapphire substrate were investigated. The transport properties of the 2DEG at room temperature were characterised by sheet carrier concentrations up to 2.0×1013 cm–2 at a mobility of 1450 cm2/Vs. Unpassivated devices with gate lengths of LG = 1 µm and a gate‐drain spacing of 5 µm exhibit maximum drain current densities of 1.2 A/mm at VGS = 2 V and extrinsic transconductances of 243 mS/mm, respectively. The small‐signal behaviour is characterised by a current gain cut‐off frequency fT = 13 GHz and a maximum frequency of oscillation fmax= 29 GHz, respectively. Pulsed I‐V measurements from different quiescent bias points reveal dispersion effects resulting in a partial drain current collapse. A SiN passivation was found not to alleviate these effects. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Enhancement‐mode AlGaN/GaN HEMTs with thin InGaN cap layer
Authors: Ito M. , Kishimoto S. , Nakamura F. , Mizutani T. 
Published: March 2008

AbstractAlGaN/GaN HEMTs with a thin InGaN cap layer has been proposed to implement the normally‐off HEMTs. The key idea is to employ the polarization‐induced field in the InGaN cap layer, by which the conduction band is raised leading to the normally‐ off operation. Fabricated HEMT with an In0.2Ga0.8N cap layer with a thickness of 5 nm showed normally‐off operation with a threshold voltage of 0.4 V and a maximum transconductance of 85 mS/mm forthe device with a 1.9‐μm‐long gate. By etching‐off the In0.2Ga0.8N cap layer at the access region using gate electrode as an etching mask, the maximum transconductance has increased from 85 to 130 mS/mm due to a reduction of the parasitic source resistance. The transconductance was increased from 130 to 145 mS/mm by annealing the devices at 250 °C for 20 minutes in a N2atmosphere. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Azimuthal anisotropy of light extraction from photonic crystal light‐emitting diodes
Authors: Lai Chun‐Feng , Kuo H. C. , Chao C. H. , Hsueh H. T. , Wang J.‐F. T. , Yeh W. Y. , Chi J. Y. , Lu T. C. , Wang S. C. 
Published: March 2008

AbstractPhotonic crystal (PhC) light‐emitting diodes (LEDs) exhibiting anisotropic light extraction have been investigated experimentally and theoretically. It is found that the anisotropic light extraction strongly depends on the lattice constant and orientation. Optical images of the anisotropy in the azimuthal direction are obtained using annular structure with triangular lattice. 6‐fold symmetric light extraction patterns with varying number of petals are observed. More petals in multiple of 6 appear in the observed image with lattice constant increasing. This anisotropic behavior suggests a new means to optimize the PhC design of GaN LED for light extraction. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
MOVPE high quality GaN film grown on Si (111) substrates using a multilayer AlN buffer
Authors: Lin Kung‐Liang , Chang Edward‐Yi , Huang Jui‐Chien , Huang Wei‐Ching , Hsiao Yu‐Lin , Chiang Chen‐Hao , Li Tingkai , Tweet Doug , Maa Jer‐Shen , Hsu Sheng‐Teng 
Published: March 2008

AbstractHigh quality GaN films were successfully grown on Si (111) substrates using the MOVPE method and a multilayer AlN buffer. The buffer layer film quality and thickness are critical for the growth of the crack‐free GaN film on Si (111) substrates. Cracks started to form on the single layer high temperature (HT) AlN film grown on Si (111) substrate as the AlN thickness was greater than 20 nm. However, a 100 nm crack‐free AlN film can be obtained when multilayer buffer of HT‐AlN/low temperature (LT)‐AlN/HT‐AlN was grown on the Si (111) substrate. By using multilayer AlN buffer, a 2 μm crack‐free GaN film was successful grown on the 2” Si (111) substrate. Moreover, the GaN film (2μm thick) grown on Si with a GaN (004) Mosaic FWHM of only 0.12°. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparative study of temperature‐dependent electroluminescence efficiency in blue and green (In,Ga)N multiple‐quantum‐well diodes
Authors: Jimi H. , Inada T. , Horiguchi M. , Satake A. , Fujiwara K. 
Published: March 2008

AbstractElectroluminescence (EL) efficiency is comparatively investigated in the c ‐plane blue and green multiple‐quantum‐well (MQW) diodes over a wide temperature range (20‐300 K) and as a function of injection current (0.01‐10 mA). One striking result of the external quantum efficiency ηex observed is that for the blue diode strong EL quenching can occur at temperatures below 100 K in agreement with the previous reports, while no significant EL collapse is seen below 100 K for the green MQW diode, especially at low injection currents. This means that the anomalous low temperature EL reduction observed for the blue (In,Ga)N MQW diode is not solely determined by temperature only but strongly modified by changing the In content in the active layers, suggesting mechanisms ruled by forward‐bias dependent weaker carrier capture for the shallow potential depth MQW rather than hole freeze‐out at deep Mg acceptors. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
InGaN/GaN laser diodes on semipolar (10$\bar 1$$\bar 1$) bulk GaN substrates
Authors: Tyagi Anurag , Zhong Hong , Chung Roy B. , Feezell Daniel F. , Saito Makoto , Fujito Kenji , Speck James S. , DenBaars Steven P. , Nakamura Shuji 
Published: March 2008

AbstractThe first semipolar nitride laser diodes (LDs) have been realized on low extended defect density semipolar (10$\bar 1$$\bar 1$) GaN bulk substrates. The LDs were grown by conventional metal organic chemical vapor deposition (MOCVD). Broad area lasers with uncoated etched facets were fabricated and tested under pulsed conditions. Lasing was observed at a duty cycle of 0.025% with the threshold current density (Jth) being 24.5 kA/cm2 for a 5 µm × 800 µm device. An output power of 65 mW was measured from a single facet of the device at a drive current of 1.5 A, with the calculated differential quantum efficiency (ηdiff) being 8%. Stimulated emission was observed at 405.9 nm with a narrow full width half maximum (FWHM) of less than 0.3 nm. The lowest measured Jth was 16.5 kA/cm2 for a 10 µm × 800 µm device. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
AlN/GaN superlattice quality improvement by using multiple superlattice structure
Authors: Veis M. , Hagihara K. , Nakagawa S. , Inoue Y. , Ishida A. 
Published: March 2008

AbstractWe report on an improvement of structural and morphological quality of AlN/GaN superlattices when the multiple superlattice (MSL) structure is used. Such a structure contains strained AlN/GaN simple superlattices with a small number of periods separated by thick GaN layer. Hot wall epitaxy technique (HWE) was used to grow these structures and atomic force microscopy (AFM) as well as X‐ray diffraction measurements were used to obtain the information about their structural and morphological properties. According to AFM measurements, the threading dislocation density and the surface roughness were decreased compare to the simple superlattice. Xray rocking curve (XRC) measurements exhibit narrower peaks, so the full width at half maximum (FWHM) of the 0th superlattice peak was decreased by 37%. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Near‐infrared intersubband emission from GaN/AlN quantum dots and quantum wells
Authors: Nevou L. , Julien F. H. , Tchernycheva M. , Guillot F. , Sarigiannidou E. , Monroy E. 
Published: March 2008

AbstractWe report on the observation of intersubband luminescence at room temperature from GaN/AlN quantum wells and quantum dots. The quantum wells are designed to exhibit three bound states in the conduction band. Optical pumping resonant with the e1‐e3 transition (λ = 0.98 μm) is used to populate the e3 excited state. Emission corresponding to the e3‐e2 transition is observed peaked at 2.13 (2.3) μm for heavily (lightly) doped quantum wells. We also report on the observation of room temperature emission at λ ≈ 1.5 μm from a stack of GaN/AlN QDs through resonantly‐enhanced Raman scattering involving GaN LO‐phonons. The quantum dot emission is ascribed to the pz‐s intraband transition of the dots. We show that this process provides room for population inversion. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Inhomogeneously broadened optical gain spectra of InGaN quantum well laser diodes
Authors: Kojima Kazunobu , Funato Mitsuru , Kawakami Yoichi , Braun Harald , Schwarz Ulrich , Nagahama Shinichi , Mukai Takashi 
Published: March 2008

AbstractOptical gain of InGaN quantum well laser diodes and its internal field dependences are investigated. Gain spectra are experimentally measured by the Hakki‐Paoli method. Inhomogeneous broadening of the gain spectra as well as of the electroluminescence spectra increases with In content of the active layers due to potential fluctuation. From measured carrier decay times and current density, we estimated the carrier density for which modal gain overcomes internal loss. We present gain calculation including quantum confined Stark effect, Coulomb screening and valence band structure simultaneously. Calculated and measured carrier densities are in good agreement. In InGaN quantum well laser diodes working at 470 nm, the quantum confined Stark effect reduces the optical transition probability down to 30% of its value without internal field. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Improvement in performance of m‐plane GaInN light emitting diode grown on m‐plane SiC by sidewall epitaxial lateral overgrowth
Authors: Kawashima T. , Hayakawa T. , Hayashi M. , Nagai T. , Iida D. , Miura A. , Kasamatsu Y. , Iwaya M. , Kamiyama S. , Amano H. , Akasaki I. 
Published: March 2008

AbstractGaInN‐based light‐emitting diodes having m‐plane heterostructures and multi quantum well (MQW) were fabricated on m‐plane SiC by sidewall‐seeded epitaxial lateral overgrowth. Defects such as stacking faults or dislocations strongly affect the emission wavelength and efficiency of MQW. Control of the V/III ratio during growth is found to be very effective for growing GaN from only one sidewall, by which we can reduce the area of the high‐defect‐density region. A light emitting diode (LED) with high internal quantum efficiency and an almost single peak LED was successfully fabricated. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Local vibration modes and nitrogen incorporation in AlGaAs:N layers
Authors: Gallardo E. , Lazić S. , Calleja J. M. , Miguel‐Sánchez J. , Montes M. , Hierro A. , Gargallo‐Caballero R. , Guzmán A. , Muñoz E. , Teweldeberhan A. M. , Fahy S. 
Published: March 2008

AbstractRaman scattering measurements in dilute AlGaAs:N films grown by plasma‐assisted molecular beam epitaxy on (100) GaAs substrates reveal strong local vibration modes (LVM) associated to N complexes. The LVM observed frequencies between 325 and 540 cm–1 are in good agreement with density functional theory supercell calculations of AlnGa4–nN complexes (n = 1,2,3,4). We find that the observed LVMs correspond to all n values including Al4N. The LVMs spectra are resonant at energies around 1.85 eV. The values of the extended phonon frequencies of the ternary compound (GaAs and AlAs‐like) reveal changes in the N distribution depending on the growth conditions: A transition from random‐ to non‐random nitrogen distribution is observed upon increasing the growth temperature. Our results confirm the preferential bonding of N to Al in AlGaAs:N, due to the higher Al‐N bond strength as compared to the Ga‐N bond. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Raman scattering by coupled plasmon‐LO phonons in InN nanocolumns
Authors: Lazić S. , Gallardo E. , Calleja J.M. , Agulló‐Rueda F. , Grandal J. , Sánchez‐García M.A. , Calleja E. 
Published: March 2008

AbstractRaman measurements on high quality, relaxed InN nanocolumns grown on Si(001) and Si(111) substrates by plasma‐assisted molecular beam epitaxy are reported. A coupled LO phonon‐plasmon mode around 430 cm–1, together with the uncoupled LO phonon appears in the nanocolumnar samples. The coupled mode is attributed to spontaneous accumulation of electrons at the lateral surfaces of the nanocolumns, while the uncoupled phonon originates from their inner part. Infrared reflectance measurements confirm the presence of electrons in the nanocolumns. The electron density in the accumulation layer depends on the growth temperature and is sensitive to exposure of HCl. Our results indicate that accumulation of intrinsic electrons occurs not only at the polar surfaces of InN layers, but also on non‐polar lateral surfaces of InN nanocolumns. Its origin is attributed to an In‐rich surface reconstruction of the nanocolumns sidewalls. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Adapter for contact force sensing of the da Vinci® robot
Authors: Shimachi Shigeyuki , Hirunyanitiwatna Surakij , Fujiwara Yasunori , Hashimoto Akira , Hakozaki Yoshinori 
Published: March 2008

AbstractBackgroundAt present, the da Vinci® surgical robot system does not provide haptic feedback. One of the authors has proposed a contact‐force sensing method called the ‘overcoat method’, in which the instrument/driver is supported by force sensors. In the da Vinci robot, the instrument jaws are powered by a wire‐pulley mechanism; thus, in order to apply the overcoat method to the da Vinci system, we must transfer the power through a frame that is supported by force sensors.MethodsThe authors have attempted to add a force‐sensor function to the Sterile Adapter® of the da Vinci system. In developing a sensorized adapter, a new configuration of force sensors and a new axial‐force‐free (AFF) joint have been devised in order to obtain an independent ‘axial force effect’ from the drive torque fed from the da Vinci robot arm.ResultsThe force‐sensing errors of the present system have been measured to have a maximum value of approximately 0.2 N while driving the jaws, and a maximum value of approximately 0.2 N when the robot arm is inclined with some excitation. Some impact reference forces applied on to the ends of the jaws agree with the outputs of the sensorized adapter to within <0.05 N.DiscussionsIt is shown that the new adapter can be sterilized. One apprehension is that the total weight of the new adapter—approximately 1.2 kg—might unbalance the robot arm. In the case of the new adapter, the centre‐line of the instrument shaft is shifted externally through approximately 3.5 mm from its original position. However, a new cannula for the da Vinci robot might solve this problem.ConclusionThe new configuration of force sensors and the new AFF joint work well in their basic functions. The total force‐sensing error is estimated as approximately 0.5 N. One of the main reasons for the error appears to be the deformation of the adapter frame. Copyright © 2008 John Wiley & Sons, Ltd.
Figuring of elliptical hard X‐ray focusing mirror using 1‐dimensional numerically controlled local wet etching
Authors: Yamamura Kazuya , Takai Hiroyuki 
Published: March 2008

AbstractNumerically controlled local wet etching (NC‐LWE) is a novel figuring method for fabricating the ultraprecision optics or finishing the functional materials. In this method, the localized etching area is formed by applying the combination nozzle that is constructed from the supply part and the suction part of the etchant, and the removal volume anywhere on the workpiece surface is determined by the dwelling time of the nozzle. We applied the NC‐LWE for fabricating the plano‐elliptical mirror made of synthesized quartz glass to focus the hard X‐ray beam, and achieved a figure error of 27 nm (p–v) by applying a 1‐dimensional numerically controlled figuring utilizing a square‐shaped nozzle. Copyright © 2008 John Wiley & Sons, Ltd.
Interface properties and effective work function of Sb‐predoped fully silicided NiSi gate
Authors: Hosoi Takuji , Sano Kosuke , Ohta Akio , Makihara Katsunori , Kaku Hirotaka , Miyazaki Seiichi , Shibahara Kentaro 
Published: March 2008

AbstractX‐ray photoelectron spectroscopy (XPS) analysis of Sb‐predoped fully silicided (FUSI) NiSi gate metal‐oxide‐semiconductor structure was carried out to evaluate the chemical bonding states and location of Sb pileup at NiSi/SiO2 interface. The results reveal that Sb atoms encroach into the SiO2 layer and that their pileup is formed at about 3 nm beneath the NiSi/SiO2 interface. Direct measurement of the work function of Sb‐doped FUSI NiSi gate by XPS suggests that the work function is identical to its original value without the Sb pileup located inside the gate oxide. Copyright © 2008 John Wiley & Sons, Ltd.
Synthesis and structure of built‐up organic macromolecules containing helicene
Authors: Amemiya Ryo , Yamaguchi Masahiko 
Published: March 2008

AbstractBuilt‐up macromolecules are acyclic molecules with molecular weights of several thousand daltons, which are synthesized by connecting small molecular units using stepwise methods. The chemical study of built‐up macromolecules reveals some noteworthy properties that are different from those of conventional biological and synthetic macromolecules. A characteristic feature of built‐up organic macromolecules is that their structures and properties are discontinuous at a certain molecular weight. For such macromolecules, variation in the small molecular units and the formation of cyclic structures substantially affect the structure and properties. The built‐up organic macromolecules obtained by connecting helicenes with amide, acetylene, and amine groups are discussed in this paper. Some chiral built‐up macromolecules are linked by covalent bonds, and the effects of linking on the structure are compared. © 2008 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 8: 116–127; 2008: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20142
Recent developments on chiral ionic liquids: Design, synthesis, and applications
Authors: Patil Mahesh L. , Sasai Hiroaki 
Published: March 2008

AbstractThe recent progress in chiral ionic liquids with respect to their syntheses and applications in enantioselective reactions and chiral recognition is described. In addition to the conventional chiral ionic liquids derived from chiral natural products, a library of novel chiral spiro compounds, including spiro bis(pyridinium) and spiro bis(imidazolium) salt, is also described. © 2008 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 8: 98–108; 2008: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20143