bluuebunny/crossref_metadata_2025 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

Background

Data 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.

Methods

This 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.

Results

In 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.

Conclusions

Nocturnal 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

The 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

Magnetic 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

Spin‐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

Lattice‐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

AlGaN/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

Photonic 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

High 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

Electroluminescence (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

The 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

We 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

We 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

Optical 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

GaInN‐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

Raman 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

Raman 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

Background

At 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.

Methods

The 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.

Results

The 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.

Discussions

It 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.

Conclusion

The 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

Numerically 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

X‐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

Built‐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

The 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
Ecological responses of Primula nutans to centimeter‐scale topographic and environmental variability in an alpine wetland
Authors: Shen Haihua , Tang Yanhong , Washitani Izumi
Published: March 2008

Primula nutans Georgi is a herbaceous species broadly distributed in wetlands on the Qinghai–Tibetan Plateau. These wetlands are often spatially highly heterogeneous because of their hummock‐and‐hollow microtopography. To address how P. nutans can be so broadly distributed on these wetlands, we examined ramet distribution, abundance, and growth performance in environmentally variable microsites at the centimeter scale. P. nutans showed significantly higher ramet density on the south‐orientated microsites than on the north‐orientated microsites. With increasing relative microsite elevation on the hummocks, ramet density increased significantly, but individual leaf area decreased significantly. Principle component analysis and multiple regression analysis indicated that microsites at higher elevations tend to have higher light availability and higher ramet density. The study suggests that P. nutans shows high plasticity in the distribution, abundance, and growth performance in response to the microtopography at the centimeter scale, which may contribute to the broad distribution of the species in the hummock‐and‐hollow wetlands in harsh alpine environments on the Tibetan Plateau.
Brain activity associated with slow temporal summation of C‐fiber evoked pain in fibromyalgia patients and healthy controls
Authors: Staud Roland , Craggs Jason G. , Perlstein William M. , Robinson Michael E. , Price Donald D.
Published: March 2008

Temporal summation of “second pain” (TSSP) is the result of C‐fiber‐evoked responses of dorsal‐horn neurons, termed “windup”. This phenomenon is dependent on stimulus frequency (≥0.33Hz) and relevant for central sensitization as well as chronic pain. Whereas, our previous functional magnetic resonance imaging (fMRI) study characterized neural correlates of TSSP in 11 healthy volunteers, the present study was designed to compare brain responses associated with TSSP across these healthy participants and 13 fibromyalgia (FM) patients. Volume‐of‐interest analysis was used to assess TSSP‐related brain activation. All participants underwent fMRI‐scanning during repetitive heat pulses at 0.33Hz and 0.17Hz to the right foot. Stimulus intensities were adjusted to each individual's heat sensitivity to achieve comparable TSSP‐ratings of moderate pain in all subjects. Experimental pain ratings showed robust TSSP during 0.33Hz but not 0.17Hz stimuli. When stimulus strength was adjusted to induce equivalent levels of TSSP, no differences in activation of pain‐related brain regions occurred across NC and FM groups. Subsequently, the fMRI‐data of both groups were combined to increase the power of our statistical comparisons. fMRI‐statistical maps identified several brain regions with stimulus and frequency dependent activation consistent with TSSP, including ipsilateral and contralateral thalamus, medial thalamus, S1, bilateral S2, mid‐ and posterior insula, rostral and mid‐anterior cingulate cortex. However, the stimulus temperatures necessary to evoke equivalent levels of TSSP and corresponding brain activity were less in FM patients. These results suggest that enhanced neural mechanisms of TSSP in FM are reflected at all pain related brain areas, including posterior thalamus, and are not the result of selective enhancement at cortical levels.
Methanogens with pseudomurein use diaminopimelate aminotransferase in lysine biosynthesis
Authors: Graham David E. , Huse Holly K.
Published: March 2008

Methanothermobacter thermautotrophicus uses lysine for both protein synthesis and cross‐linking pseudomurein in its cell wall. A diaminopimelate aminotransferase enzyme from this methanogen (MTH0052) converts tetrahydrodipicolinate to l,l‐diaminopimelate, a lysine precursor. This gene complemented an Escherichia coli diaminopimelate auxotrophy, and the purified protein catalyzed the transamination of diaminopimelate to tetrahydrodipicolinate. Phylogenetic analysis indicated this gene was recruited from anaerobic Gram‐positive bacteria. These results expand the family of diaminopimelate aminotransferases to a diverse set of plant, bacterial and archaeal homologs. In contrast marine methanogens from the Methanococcales, which lack pseudomurein, appear to use a different diaminopimelate pathway for lysine biosynthesis.
Vanadate proliferative and anti‐mineralogenic effects are mediated by MAPK and PI‐3K/Ras/Erk pathways in a fish chondrocyte cell line
Authors: Tiago Daniel M. , Cancela M. Leonor , Aureliano Manuel , Laizé Vincent
Published: March 2008

We recently reported proliferative and anti‐mineralogenic effects of vanadate on fish chondrocytes and here we investigate the signalling pathways associated with these effects. Our data show that vanadate stimulates chondrocyte proliferation through the MAPK pathway, using signalling mechanisms similar to those used by IGF‐1, while it inhibits chondrocyte differentiation/mineralization through a putative PI‐3K/Ras/Erk signalling, a pathway shared with insulin. Our data also suggest that vanadate impairs ECM mineralization not only by interfering with regulatory pathways but also by inhibiting enzymatic activity of ALP. Finally, this work provides additional evidence for the conservation, throughout evolution, of mechanisms regulating chondrocyte proliferation and differentiation.
The Nursing Profession
Authors: Craig Lora
Published: March 2008

THE NURSING PROFESSION by Fred Davis, 203 pages, John Wiley and Sons, Inc., New York. Price $6.95.
Patients of immigrant origin in inpatient psychiatric facilities
Authors: Schouler-Ocak M. , Bretz H.J. , Penka S. , Koch E. , Hartkamp N. , Siefen R.G. , Schepker R. , Özek M. , Hauth I. , Heinz A.
Published: March 2008

In a representative nationwide survey, the Psychiatry and Migration Working Group of the German Federal Conference of Psychiatric Hospital Directors (Bundesdirektorenkonferenz) examined the use of inpatient psychiatric and psychotherapeutic services in Germany by patients of immigrant origin. Questionnaires were sent to a total of 350 general hospital psychiatric clinics throughout Germany, and 131 clinics responded. As shown by the 2005 Microcensus [22], almost one-fifth (18.6%) of the German population is of immigrant origin. In our study, persons of immigrant origin comprised 17% of patients in the responding facilities. This indicates that the percentage of inpatient psychiatric services used by patients of immigrant origin is almost proportionate to these patients’ percentage of the general population. The largest group of immigrant patients in our study were those of Russian heritage, followed by patients of Turkish, Arabic, or other origin. Almost two-thirds of the immigrant patients were born in Germany, and a considerably larger percentage were German citizens (74%). Sixty-two per cent of all patients of immigrant origin spoke a language other than German (e.g. Russian, Turkish, Polish) at home. Patients of immigrant origin were significantly more likely to receive an ICD-10 F2 diagnosis, and it was precisely patients with this diagnosis who were observed to experience difficulties in communication with caregivers.
Cultural competency training in psychiatry
Authors: Qureshi A. , Collazos F. , Ramos M. , Casas M.
Published: March 2008

Recent reports indicate that the quality of care provided to immigrant and ethnic minority patients is not at the same level as that provided to majority group patients. Although the European Board of Medical Specialists recognizes awareness of cultural issues as a core component of the psychiatry specialization, few medical schools provide training in cultural issues. Cultural competence represents a comprehensive response to the mental health care needs of immigrant and ethnic minority patients. Cultural competence training involves the development of knowledge, skills, and attitudes that can improve the effectiveness of psychiatric treatment. Cognitive cultural competence involves awareness of the various ways in which culture, immigration status, and race impact psychosocial development, psychopathology, and therapeutic transactions. Technical cultural competence involves the application of cognitive cultural competence, and requires proficiency in intercultural communication, the capacity to develop a therapeutic relationship with a culturally different patient, and the ability to adapt diagnosis and treatment in response to cultural difference. Perhaps the greatest challenge in cultural competence training involves the development of attitudinal competence inasmuch as it requires exploration of cultural and racial preconceptions. Although research is in its infancy, there are increasing indications that cultural competence can improve key aspects of the psychiatric treatment of immigrant and minority group patients.
Aspects of rumen microbiology central to mechanistic modelling of methane production in cattle
Authors: ELLIS J. L. , DIJKSTRA J. , KEBREAB E. , BANNINK A. , ODONGO N. E. , McBRIDE B. W. , FRANCE J.
Published: March 2008

Methane, in addition to being a significant source of energy loss to the animal that can range from 0·02 to 0·12 of gross energy intake, is one of the major greenhouse gases being targeted for reduction by the Kyoto protocol. Thus, one of the focuses of recent research in animal science has been to develop or improve existing methane prediction models in order to increase overall understanding of the system and to evaluate mitigation strategies for methane reduction. Several dynamic mechanistic models of rumen function have been developed which contain hydrogen gas balance sub-models from which methane production can be predicted. These models predict methane production with varying levels of success and in many cases could benefit from further development. Central to methane prediction is accurate volatile fatty acid prediction, representation of the competition for substrate usage within the rumen, as well as descriptions of protozoal dynamics and pH. Most methane models could also largely benefit from an expanded description of lipid metabolism and hindgut fermentation. The purpose of the current review is to identify key aspects of rumen microbiology that could be incorporated into, or have improved representation within, a model of ruminant digestion and environmental emissions.
Mixed Lagrangian–Eulerian description of vortical flows for ideal and viscous fluids
Authors: KUZNETSOV E. A.
Published: March 2008

It is shown that the Euler hydrodynamics for vortical flows of an ideal fluid is equivalent to the equations of motion of a charged compressible fluid moving due to a self-consistent electromagnetic field. The velocity of new auxiliary fluid coincides with the velocity component normal to the vorticity line for the primitive equations. Therefore this new hydrodynamics represents hydrodynamics of vortex lines. Their compressibility reveals a new mechanism for three-dimensional incompressible vortical flows connected with breaking (or overturning) of vortex lines which can be considered as one of the variants of collapses. Transition to the Lagrangian description in the new hydrodynamics corresponds, for the original Euler equations, to a mixed Lagrangian–Eulerian description – the vortex line representation (VLR). The Jacobian of this mapping defines the density of vortex lines. It is shown also that application of VLR to the Navier–Stokes equations results in an equation of diffusive type for the Cauchy invariant. The diffusion tensor for this equation is defined by the VLR metric.
Unsteady flows in pipes with finite curvature
Authors: SIGGERS J. H. , WATERS S. L.
Published: March 2008

Motivated by the study of blood flow in a curved artery, we consider fluid flow through a curved pipe of uniform curvature, δ, driven by a prescribed oscillatory axial pressure gradient. The curved pipe has finite (as opposed to asymptotically small) curvature, and we determine the effects of both the centrifugal and Coriolis forces on the flow. In addition to δ, the flow is parameterized by the Dean number, D, the Womersley number, α, and a secondary streaming Reynolds number, Rs. Asymptotic solutions are developed for the case when δ≪1, α≪1 and the magnitude of the axial pressure gradient is small, using regular perturbation techniques. For intermediate values of the governing parameters, a pseudospectral code is used to obtain numerical solutions. For flows driven by a sinusoidal pressure gradient (D=0), we identify three distinct classes of stable solutions: 2π-periodic symmetric, 2π-periodic asymmetric, and asymmetric solutions that are either quasi-periodic, or periodic with period 2πk for k∈ $\mathbb{N}$. The transition between solutions is dependent on the value of δ; thus pipes with finite curvature may exhibit qualitatively different transitions between the solution classes as the governing parameters are varied from those of curved pipes with asymptotically small curvature. When α≫1, matched asymptotic expansions are used to simplify the system, and the resulting equations are solved analytically for Rs≪1, δ≪1 and numerically for larger parameter values. We then determine the effect of a non-zero steady component of the pressure gradient (D≠0), and show that, for certain parameter values, when D is above a critical value the periodic asymmetric solutions regain spatial symmetry. Finally, we show that the effects of finite curvature can lead to substantial quantitative differences in the wall shear stress distribution and discuss briefly the physiological implications of the results for blood flow in arteries.
The aeroacoustics of slowly diverging supersonic jets
Authors: GOLDSTEIN M. E. , LEIB S. J.
Published: March 2008

This paper is concerned with utilizing the acoustic analogy approach to predict the sound from unheated supersonic jets. Previous attempts have been unsuccessful at making such predictions over the Mach number range of practical interest. The present paper, therefore, focuses on implementing the refinements needed to accomplish this objective. The important effects influencing peak supersonic noise are found to be source convection, mean flow refraction, mean flow amplification, and source non-compactness. It appears that the last two effects have not been adequately dealt with in the literature. For the first of these this is because the usual parallel flow models produce most of the amplification in the so-called critical layer where the solution becomes singular and, therefore, causes the predicted sound field to become infinite. We deal with this by introducing a new weakly non-parallel flow analysis that eliminates the critical layer singularity. This has a strong effect on the shape of the peak noise spectrum. The last effect places severe demands on the source models at the higher Mach numbers because the retarded-time variations significantly increase the sensitivity of the radiated sound to the source structure in this case. A highly refined (non-separable) source model is, therefore, introduced in this paper.
Experimental and numerical investigation of inertial particle clustering in isotropic turbulence
Authors: SALAZAR JUAN P. L. C. , DE JONG JEREMY , CAO LUJIE , WOODWARD SCOTT H. , MENG HUI , COLLINS LANCE R.
Published: March 2008

This paper presents the first detailed comparisons between experiments and direct numerical simulations (DNS) of inertial particle clustering in nearly isotropic ‘box turbulence’. The experimental system consists of a box 38cm in each dimension with fans in the eight corners that sustain nearly isotropic turbulence in the centre of the box. We inject hollow glass spheres with a mean diameter of 6 μm and measure the locations of several hundred particles in a 1 cm3volume in the centre of the box using three-dimensional digital holographic particle imaging. We observe particle concentration fluctuations that result from inertial clustering (sometimes called ‘preferential concentration’). The radial distribution function (RDF), a statistical measure of clustering, has been calculated from the particle position field. We select this measure because of its relevance to the collision kernel for particles. DNS of the equivalent system, with nearly perfect parameter overlap, have also been performed. We observe good agreement between the RDF predictions of the DNS and the experimental observations, despite some challenges in the interpretation of the experiments. The results provide important guidance on ways to improve the measurement.
Comparison between experiments and direct numerical simulations in a channel flow with roughness on one wall
Authors: BURATTINI P. , LEONARDI S. , ORLANDI P. , ANTONIA R. A.
Published: March 2008

The turbulent flow in a two-dimensional channel with roughness on one wall is investigated using experiments and direct numerical simulations (DNS). The elements have a square cross-section with height k=0.1H (H is the channel half-width) and a streamwise spacing of 4k. The Reynolds number Reτr, based on the friction velocity at the rough wall and H, is in the range 300–1100. Particular attention is given to the rough-wall side. Measured turbulence intensities, length scales, leading terms in the turbulent kinetic energy budget, and velocity spectra are compared with those obtained from the DNS. Close agreement is found, yielding support for the simplifying assumptions in the experiment (notably local isotropy and Taylor's hypothesis) and the adequacy of the spatial resolution in the simulation. Overall, the profiles of the Reynolds normal stresses on the roughness side are almost independent of Reτr, when normalized by outer variables. Energy spectra at different locations above the rough wall collapse well at high wavenumbers, when normalized by Kolmogorov scales. In contrast to previous studies, a region of negative energy production near the location of the maximum streamwise velocity is not observed. Comparison with a smooth-wall channel, at similar values of the friction-velocity Reynolds number, highlights differences only in the streamwise velocity component near the wall.
Nicotine dependence and mental disorders among adults in the USA: evaluating the role of the mode of administration
Authors: Goodwin R. D. , Zvolensky M. J. , Keyes K. M.
Published: March 2008

Background

To investigate the association between nicotine dependence (ND), by cigarette smoking and use of smokeless tobacco (UST), and mental disorders.

Method

Face-to-face surveys (n=43 093) were conducted in the 2001–2002 National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). Nicotine use, ND, and mental disorders were assessed using DSM-IV criteria.

Results

UST-ND was associated with a significantly increased likelihood of any anxiety disorder, specific phobia, alcohol abuse and dependence. Consistent with previous findings, cigarette smoking-ND was associated with an increased likelihood of all mental disorders examined. Among those without ND, cigarette smoking was specifically associated with panic attacks and panic disorder; non-dependent UST was not associated with mental disorders.

Conclusions

Our findings suggest that the association between ND and mental disorders is relatively specific to the mode of nicotine administration. Among those who are nicotine dependent, cigarette use is associated with most major psychiatric disorders, whereas UST is associated with dysthymia and specific phobia. Among those who use tobacco but are not nicotine dependent, cigarette use is associated with dysthymia and panic disorder; UST is not associated with any major mood or anxiety disorders. The link between mental disorders and nicotine is complex, and is associated primarily with dependence, and not with non-dependent use.
Ambient seismic noise tomography and structure of eastern North America
Authors: Liang Chuntao , Langston Charles A.
Published: March 2008

The time derivative of cross‐correlation functions (CCF) of ambient noise fields recorded by two stations can be approximated as the Green's Function (GF) between the stations. The CCFs are thus used as Peudo‐GFs (dominated by surface waves) to invert for group velocity structure in eastern North America. Stations from two regional networks deployed to monitor the New Madrid Seismic Zone and eastern Tennessee seismic zone, together with stations of the US National Seismic Network, greatly improve tomographic ray coverage. The short period (T = 5 s) group velocity map shows strong correlations with the depth to Precambrian basement. Many subtle local structures can be clearly identified from the velocity map, including the Ozark uplift, Cincinnati Arch, Nashville Dome and the Blue Ridge province of the Appalachians showing relatively high group velocity. The long period (T = 15 s) group velocity map shows strong correlations with regional geology. Ancient rift basins, such as the Mid‐Continent Rift (MCR) system, the Reelfoot rift, the Oklahoma Aulacogen and the Eastern Continent Rift, are associated with low velocity belts along their rift axes. We also find that all major seismic zones in eastern North America, such as the New Madrid seismic zone, Eastern Tennessee seismic zone as well as Ouachita Orogen seismic zone, are approximately located at transition zones separating velocity highs and lows. This observation suggests that those seismic zones may reflect the reactivation of ancient faults associated with continental rift and collision zones.
Validation of Aura Microwave Limb Sounder O3 and CO observations in the upper troposphere and lower stratosphere
Authors: Livesey N. J. , Filipiak M. J. , Froidevaux L. , Read W. G. , Lambert A. , Santee M. L. , Jiang J. H. , Pumphrey H. C. , Waters J. W. , Cofield R. E. , Cuddy D. T. , Daffer W. H. , Drouin B. J. , Fuller R. A. , Jarnot R. F. , Jiang Y. B. , Knosp B. W. , Li Q. B. , Perun V. S. , Schwartz M. J. , Snyder W. V. , Stek P. C. , Thurstans R. P. , Wagner P. A. , Avery M. , Browell E. V. , Cammas J.‐P. , Christensen L. E. , Diskin G. S. , Gao R.‐S. , Jost H.‐J. , Loewenstein M. , Lopez J. D. , Nedelec P. , Osterman G. B. , Sachse G. W. , Webster C. R.
Published: March 2008

Global satellite observations of ozone and carbon monoxide from the Microwave Limb Sounder (MLS) on the EOS Aura spacecraft are discussed with emphasis on those observations in the 215–100 hPa region (the upper troposphere and lower stratosphere). The precision, resolution and accuracy of the data produced by the MLS “version 2.2” processing algorithms are discussed and quantified. O3 accuracy is estimated at ∼40 ppbv +5% (∼20 ppbv +20% at 215 hPa) while the CO accuracy is estimated at ∼30 ppbv +30% for pressures of 147 hPa and less. Comparisons with expectations and other observations show good agreements for the O3 product, generally consistent with the systematic errors quoted above. In the case of CO, a persistent factor of ∼2 high bias is seen at 215 hPa. However, the morphology is shown to be realistic, consistent with raw MLS radiance data, and useful for scientific study. The MLS CO data at higher altitudes are shown to be consistent with other observations.