bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of the longitudinal and circumferential left ventricular function at rest and during exercise in healthy elderly individuals by tissue-Doppler echocardiography: relationship with heart rate
Authors: QUINTANA Miguel , SAHA Samir K. , ROHANI Morteza , FURIA Francesca DEL , BJERNBY Johanna , LIND Britta , BRODIN Lars-Åke
Published: April 2004

Tissue-Doppler echocardiography (TDE) has been introduced to quantify stress echocardiography by means of assessing the left ventricular (LV) segmental myocardial velocities and excursion. The interaction between LV long- and short-axis function during physical exercise has not been elucidated completely. The aim of the present study was to investigate long- and short-axis LV function, as assessed by myocardial velocities and excursions at rest and during exercise and its possible relationship with heart rate in healthy elderly individuals by TDE. Twenty-seven individuals underwent an exercise test in the supine position on a bicycle ergometer. The initial workload was 30 Watts, followed by 20-Watt increments every third minute. Standard echocardiographic images with super-imposed colour TDE were digitized at the end of each step. The following variables were studied in the LV long- and short-axis: myocardial peak systolic velocity (PSV) and excursion, isovolumic contraction and relaxation times, peak velocity at early diastole (E´-wave) and peak velocity at late diastole (A´-wave) and the E´/A´ ratio. Increments in myocardial peak systolic velocity and excursion in the LV long-axis were more pronounced during low workloads. The increase in those variables in the short-axis occurred mainly at higher exercise loads. The improvement in LV long- and short-axis functions was closely related to the increase in the heart rate. Shortening of the isovolumic contraction and relaxation times occurred only at the initial stages of exercise. An increase in the long-axis E´/A´ ratio occurred during exercise, whereas this ratio was unchanged in the short-axis. In conclusion, during exercise, the LV long- and short-axis functions behave differently, and increases in LV long- and short-axis functions are related to changes in heart rate. Therefore, in the interpretation of echocardiographic findings during exercise stress echocardiography, these facts have to be taken into account.
17β-Oestradiol enhances aortic endothelium function and smooth muscle contraction in male spontaneously hypertensive rats
Authors: YEN Chia-Hung , LAU Ying-Tung
Published: April 2004

17β-Oestradiol (E2; oestrogen) is known to increase endothelium-dependent vasodilatation and NO (nitric oxide) production. It is also known to decrease the response of VSMCs (vascular smooth muscle cells) to vasoconstrictors in vitro. E2 induces a decrease in age-related BP (blood pressure) development in MSHR (male spontaneously hypertensive rats). Whether this decrease is due to an effect on the endothelium or smooth muscle is unknown. To determine this effect, we examined the role of E2 on vascular endothelium and smooth muscle separately. We treated MSHR with E2 (2 mg·kg-1 of body weight·week-1) for 5–7 weeks and then examined the vasoconstrictor response in the intact and denuded rings (with or without endothelium respectively). SBP (systolic BP) was measured weekly. Aortic cGMP and cAMP contents, aortic vasoconstrictor response, endothelium suppression of the vasoconstrictor response and basal NO release from aortic rings were all measured at the end of the study. We found that the age-related development of SBP in MSHR was decreased in E2-treated rats. The vascular response of denuded rings to a vasoconstrictor (phenylephrine and KCl) was increased in E2-treated rats; however, this phenomenon was masked in intact rings. The enhanced endothelial function appears to override the E2-increased smooth muscle vasoconstrictor response. Endothelium suppression, NO release and aortic cGMP content were all significantly higher in E2-treated rats than in controls. Thus our results suggest that E2 improves endothelium function; furthermore, the accompanied NO/cGMP increase and the endothelium suppression may be associated with an E2-induced BP-lowering effect in MSHR.
Elevated secretory non-pancreatic type II phospholipase A2 serum activity is associated with impaired endothelial vasodilator function in patients with coronary artery disease
Authors: FICHTLSCHERER Stephan , KASZKIN Marietta , BREUER Susanne , DIMMELER Stefanie , ZEIHER Andreas M.
Published: April 2004

Low-grade inflammatory activity is associated with an increased risk for ischaemic coronary events. sPLA2 (secretory non-pancreatic type II phospholipase A2) serum activity is increased in chronic inflammatory diseases and may also contribute to atherogenesis. Since the endothelium is a major target for inflammatory cytokines, we hypothesized that elevated serum activity of sPLA2 is associated with an impaired vasodilator function in patients with documented CAD (coronary artery disease). Endothelium-dependent (acetylcholine, 10–50 µg/min) and endothelium-independent (sodium nitroprusside, 2–8 µg/min) FBF (forearm blood flow) responses were measured by venous occlusion plethysmography in 50 male patients with angiographically documented CAD. sPLA2 serum activity was inversely correlated with acetylcholine-induced FBF responses (r=-0.36; P<0.05). In addition, there was a significant correlation between sPLA2 and CRP (C-reactive protein; r=0.33, P<0.02). In contrast, FBF responses to sodium nitroprusside did not correlate with sPLA2 serum activity. In order to identify independent predictors of an impaired endothelium-dependent vasodilator function in patients with CAD, a multivariate analysis was performed including the inflammatory serum markers as well as classical risk factors of CAD. This analysis demonstrated that both sPLA2 (P<0.05) and CRP serum levels (P<0.05) were the only significant independent predictors of an impaired acetylcholine-induced FBF response. In conclusion, elevated sPLA2 serum activity is associated with a significant impairment in systemic endothelial vasodilator function in patients with CAD. The identification of sPLA2 as a novel independent predictor for endothelial dysfunction provides another important clue to link a systemic marker of inflammation with coronary atherosclerotic disease.
Depth-resolving structural analysis of GaN layers by skew angle x-ray diffraction
Authors: Reiher A. , Bläsing J. , Dadgar A. , Krost A.
Published: April 2004

The method of skew angle x-ray diffraction is presented as the example of GaN-based light emitting diodes (LED) grown by metalorganic vapor phase epitaxy on silicon substrates. This technique in conjunction with a newly developed calculation algorithm allows the depth-resolving structural analysis of multilayer structures. The analysis algorithm, basing on a triangular matrix approximation for the intensity decrease in dependence on the layer depth, the absorption coefficient, and the incident angle, provides information on the real full width at half maximum (FWHM) values of the GaN (101_3) reflection in distinct depths of the device. The sensitivity of this technique was found to be smaller than 50 nm. We show the different characteristics of the measured and calculated FWHMs for two GaN-based LEDs containing a fivefold InGaN/GaN-multi-quantum well.
Influence of Pt addition on the texture of NiSi on Si(001)
Authors: Detavernier C. , Lavoie C.
Published: April 2004

We report on the texture of Ni1−xPtxSi films on Si(001) substrates. X-ray diffraction measurements in Bragg–Brentano geometry appear to indicate that pure NiSi films are randomly oriented, while the addition of Pt was reported to induce an epitaxial alignment. However, detailed texture analysis using pole figure measurements shows that pure NiSi films are in fact strongly textured. The NiSi grains exhibit five different types of preferential orientation. The addition of an increasing amount of Pt gradually changes these five texture components. This texture evolution can be understood on the basis of the expansion of the monosilicide unit cell, caused by the incorporation of Pt.
Formation mechanism of wide stacking faults in nanocrystalline Al
Authors: Liao X. Z. , Srinivasan S. G. , Zhao Y. H. , Baskes M. I. , Zhu Y. T. , Zhou F. , Lavernia E. J. , Xu H. F.
Published: April 2004

A full dislocation often dissociates into two partial dislocations enclosing a stacking fault (SF) ribbon. The SF width significantly affects the mechanical behavior of metals. Al has very high stacking fault energy and, consequently, very narrow SF width in its coarse-grained state. We have found that some SFs in nanocrystalline Al are surprisingly 1.4–6.8 nm wide, which is 1.5–11 times higher than the reported experimental value in single crystal Al. Our analytical model shows that such wide SFs are formed due to the small grain size and possibly also to the interaction of SF ribbons with high density of dislocations.
Photoreflectance investigations of oscillator strength and broadening of optical transitions for GaAsSb–GaInAs/GaAs bilayer quantum wells
Authors: Kudrawiec R. , Se̢k G. , Ryczko K. , Misiewicz J. , Harmand J. C.
Published: April 2004

GaAsSb–GaInAs/GaAs bilayer quantum wells which consist of two adjacent layers of GaAsSb and GaInAs sandwiched between GaAs barriers have been investigated by photoreflectance (PR) spectroscopy. The oscillator strengths of optical transitions in such multiheterointerface structures have been determined from the experiment and compared with the results of envelope function calculations. Additionally, the broadening of the PR features has been analyzed and a correlation has been found with the character of the transitions: the broadening increases significantly when the type of the transition changes from direct to indirect.
Engineering molecular rings for magnetocaloric effect
Authors: Affronte M. , Ghirri A. , Carretta S. , Amoretti G. , Piligkos S. , Timco G. A. , Winpenny R. E. P.
Published: April 2004

By substituting one Cr3+(s=3/2) with Cd2+(s=0) in molecular octanuclear rings, a diluted ensemble of identical nanomagnets with a S=3/2 ground state, weakly split in zero field, is obtained. The lattice contribution and the essential parameters of the spin Hamiltonian of these uncompensated antiferromagnetic cyclic spin systems are determined by fitting specific heat data between 0.4 and 20 K in magnetic fields up to 7 T. Different entropy contributions are evaluated and results suggest a possible way of engineering molecular magnets to exploit low temperature magnetocaloric effect.
Ion beam-induced anisotropic plastic deformation of silicon microstructures
Authors: van Dillen T. , de Dood M. J. A. , Penninkhof J. J. , Polman A. , Roorda S. , Vredenberg A. M.
Published: April 2004

Amorphous silicon micropillars show anisotropic plastic shape changes upon irradiation with 30 MeV Cu ions. The transverse plastic strain rate is (2.5±0.2)×10−17 cm2/ion at 77 K, which is about one order of magnitude less than that of silica glass. In contrast, crystalline silicon pillars, irradiated under the same conditions, do not exhibit anisotropic deformation. A viscoelastic and free volume model is used to qualitatively describe the data. By irradiating partially amorphous structures a variety of silicon microshapes can be fabricated.
Spin polarization in ferromagnet/insulator/superconductor structures with the superconductor on top of the barrier
Authors: Kaiser C. , Parkin S. S. P.
Published: April 2004

The tunneling spin polarization of CoFe, NiFe, and pure Ni was measured using superconducting tunneling spectroscopy for Al2O3 tunnel barriers with the ferromagnetic material both above and below the barrier. The spin polarization was found to be very similar for Co–Fe in both cases but for Ni and Ni–Fe alloys the spin polarization was significantly lower when the Al2O3 barrier was deposited on top of the ferromagnetic material. We attribute this to oxidation of the ferromagnet at the ferromagnet/Al2O3 interface resulting from an imperfect formation of the barrier.
Low-loss photonic crystal defect waveguides in InP
Authors: Kotlyar M. V. , Karle T. , Settle M. D. , O’Faolain L. , Krauss T. F.
Published: April 2004

We have fabricated high-quality planar photonic crystal defect waveguides in InP/InGaAsP material. Using Fourier analysis of the Fabry-Pérot fringes obtained in transmission, we derive the propagation losses. Values as small as 1.8 dB/mm for waveguides consisting of three rows of missing holes (W3) were measured. We believe that the reduction in losses is due to the high quality of etching carried out using a high beam voltage–current ratio regime of chemically assisted ion-beam etching.
Raman line shape of the A1 longitudinal optical phonon in GaN
Authors: Shi L. , Ponce F. A. , Menéndez J.
Published: April 2004

High-resolution Raman measurements of the A1 longitudinal optical (LO) phonon in GaN reveal a complex line shape that can be explained in terms of the angular dispersion of LO phonons in this material. A simple geometrical model of the line shape makes it possible to extract the true anharmonic full width at half maximum 2Γ of the A1(LO) mode. The value of this parameter, 2Γ=2.4 cm−1 at 20 K, is in much better agreement with time-domain measurements by Tsen and co-workers [Appl. Phys. Lett. 72, 2132 (1998)] than any previous frequency-domain measurement. The results indicate that angular dispersion effects must be carefully considered in any analysis of Raman spectra from noncubic crystals.
Highly sensitive ac nanocalorimeter for microliter-scale liquids or biological samples
Authors: Garden J.-L. , Château E. , Chaussy J.
Published: April 2004

We developed an ultrasensitive ac nanocalorimeter for use with biological liquids by means of microfabrication technologies. The volume of the cell measurement is only 5 μL. This nanocalorimeter, tested on deionized water, allows the measurement of heat capacity variation above ±150 nJ/K (resolution of ±5×10−6) with an operating temperature ranging from −20 to 120 °C and a stability of 100 μK. Its use is demonstrated on diluted lysosyme solution measured at the frequency of 3 Hz. At 3 Hz, this ac calorimeter gives only the variation of the heat capacity during the denaturation, which allows complementary thermodynamic investigations as regards to classical differential scanning calorimetry measurements.
Blueshift of yellow luminescence band in self-ion-implanted n-GaN nanowire
Authors: Dhara S. , Datta A. , Wu C. T. , Lan Z. H. , Chen K. H. , Wang Y. L. , Chen Y. F. , Hsu C. W. , Chen L. C. , Lin H. M. , Chen C. C.
Published: April 2004

Optical photoluminescence studies are performed in self-ion (Ga+)-implanted nominally doped n-GaN nanowires. A 50 keV Ga+ focused ion beam in the fluence range of 1×1014–2×1016 ions cm−2 is used for the irradiation process. A blueshift is observed for the yellow luminescence (YL) band with increasing fluence. Donor–acceptor pair model with emission involving shallow donor introduced by point-defect clusters related to nitrogen vacancies and probable deep acceptor created by gallium interstitial clusters is responsible for the shift. High-temperature annealing in nitrogen ambient restores the peak position of YL band by removing nitrogen vacancies.
Gated-mode single-photon detection at 1550 nm by discharge pulse counting
Authors: Yoshizawa Akio , Kaji Ryosaku , Tsuchida Hidemi
Published: April 2004

Gated-mode single-photon detection using an avalanche photodiode is characterized by charge and discharge pulses, which are attributable to capacitive behavior. In this letter, the discharge pulse rather than the photon-induced avalanche pulse is counted in single-photon detection, in order to reduce after pulses. A demonstration adopts an indium–gallium–arsenide avalanche photodiode operating at 1550 nm. After-pulse probability per gate is evaluated at a repetition frequency of 5 MHz.
Preparation and optical waveguide property of metal alkoxide solution-derived Pb(Zr0.5Ti0.5)O3 thick films
Authors: Hu S. H. , Meng X. J. , Hu G. J. , Chu J. H. , Dai N. , Xu L. , Liu L. Y. , Li D. X.
Published: April 2004

Pb(Zr 0.5 Ti 0.5 ) O 3 films with thickness of about 1.5 and 3.7 μm have been deposited on single-crystal SrTiO3 substrate by a sol-gel process from nonhydrolyzed metal alkoxide precursor. X-ray diffraction shows that the films exhibit a single perovskite phase with (001)-preferred orientation. Atomic force microscopy study indicates that the PZT film possesses a crack-free and smooth surface. The optical waveguide property has been examined by the prism-film coupling experiment. Four and 12 TE modes are observed for 1.5 and 3.7 μm PZT films, respectively.
Model for the photoinduced formation of diffraction gratings in liquid-crystalline composite materials
Authors: Veltri A. , Caputo R. , Umeton C. , Sukhov A. V.
Published: April 2004

We modelize the photoinduced formation of switchable diffraction gratings in polymer-based liquid-crystalline composite materials. The model assumes that redistribution of molecules is due to mass diffusion and incorporates a realistic kinetic description of polymerization processes. Numerical simulations predict two different kinds of structure that have already been experimentally observed. Two parameters governing the phenomenon are pointed out, which determine the structure that will be formed after the curing process has been completed.
Double-transconductance-plateau characteristics in InGaAs/GaAs real-space transfer high-electron-mobility transistor
Authors: Lee Ching-Sung , Hsu Wei-Chou
Published: April 2004

Bias-tunable double-transconductance-plateau characteristics due to real-space transfer through the lowering of conduction band offset at high electric fields in a δ-doped InGaAs/GaAs high-electron-mobility transistor have been observed. Extrinsic, unpassivated peak performance values, with gate dimensions of 1×125 μm2, include the transconductance plateaus of 269 and 116 mS/mm at VDS=3 V for VGS=0 V and −1.5 V, respectively, maximum drain current density of 382 mA/mm at VDS=5.5 V, unity current gain cutoff frequency of 15.5 GHz, and maximum frequency of oscillation of 23 GHz. The present structure is promising for high-speed analog-to-digital converters or multiple-state quantizer applications.
High-germanium-content SiGe islands formed on compliant oxide by SiGe oxidation
Authors: Yin Haizhou , Hobart K. D. , Kub F. J. , Shieh S. R. , Duffy T. S. , Sturm J. C.
Published: April 2004

The oxidation of Si1−xGex islands on a compliant viscous borophosphorosilicate glass (BPSG) was utilized to achieve nearly fully relaxed Si1−xGex with germanium content up to 57%. After Si1−xGex islands were formed on BPSG by layer transfer, dry oxidation was carried out to form pure silicon dioxide on the top and to increase germanium content in the Si1−xGex layer. Surface roughening and the nonuniformity of the enhanced germanium content during the SiGe oxidation were improved by depositing a silicon dioxide capping layer before oxidation. The strain arising from the increase of germanium content was relaxed by lateral expansion of the SiGe islands, showing that dislocations were not required in the process.
Correlation of magnetic moment versus spacing distance of metastable fcc structured iron
Authors: Kong L. T. , Liu B. X.
Published: April 2004

Based on the projector augmented-wave method, ab initio calculations confirm the ground state is of ferromagnetic bcc Fe and reveal a paramagnetic state for the hcp Fe. Interestingly, the calculations predict that there exist at least three distinct magnetic orderings for the metastable fcc structured Fe—a paramagnetic and low-spin and high-spin ferromagnetic states—within a lattice constant ranging from 0.34 to 0.38 nm, and that, upon increasing the atomic volume of Fe, the magnetic moment is enhanced and can even be greater than that of the equilibrium bcc Fe.
Experimental test of the correction terms for Coulomb blockade thermometry
Authors: Devi Surita , Bergsten Tobias , Delsing Per
Published: April 2004

We have experimentally investigated the higher-order correction terms for Coulomb blockade thermometry using two-dimensional arrays of small tunnel junctions and compared our results to the theory for one-dimensional arrays. We find that the correction term for the conductance dip is two times smaller, whereas the correction term for the half-width has a slightly higher value than the theoretical prediction.
Wafer-bonded semiconductors using In/Sn and Cu/Ti metallic interlayers
Authors: Shi Frank , Chen Hao , MacLaren Scott
Published: April 2004

This work reports on the interface microstructures and interface electrical and optical properties of wafer-bonded semiconductors using In/Sn and Cu/Ti as the metallic interlayers. The interface microstructures of the wafer-bonded semiconductors were characterized using transmission electron microscopy and scanning electron microscopy. The interface imperfections and their potential influences on the interface electrical performances were discussed. The interface electrical and optical characteristics of the metal-bonded wafers were also compared with those of directly fused wafers.
Visible light-emitting diodes using a-plane GaN–InGaN multiple quantum wells over r-plane sapphire
Authors: Chitnis Ashay , Chen Changqing , Adivarahan Vinod , Shatalov Maxim , Kuokstis Edmundas , Mandavilli Vasavi , Yang Jinwei , Khan M. Asif
Published: April 2004

We report blue-purple pn-junction light-emitting diodes (LEDs) with a-plane GaN–InGaN multiple quantum well active region. The LEDs were grown over r-plane sapphire substrates. Our study has shown the low pump intensity photoluminencence and electroluminescence to be dominated by emission from the band-tail states which then saturates rapidly giving rise to band-edge emission.
Direct printing of nanoparticles and spin-on-glasses by offset liquid embossing
Authors: Wilhelm Eric J. , Jacobson Joseph M.
Published: April 2004

We describe offset liquid embossing (OLE), a method for additively printing nanoparticles and spin-on-glasses. OLE utilizes the transfer of patterned material from a polydimethylsiloxane surface of tuned wettability to a rigid or flexible substrate. Multiple layers can be aligned and printed without the need for planarization. The printing is fast (10 s transfer to substrate) and can be done at ambient conditions. Bridge-like structures were printed in spin-on-glass without etching.
Large high-frequency magnetoelectric response in laminated composites of piezoelectric ceramics, rare-earth iron alloys and polymer
Authors: Cai Ning , Nan Ce-Wen , Zhai Junyi , Lin Yuanhua
Published: April 2004

Multiferroic laminated composites consisting of lead-zirconate titanate (PZT)/polyvinylidene-fluoride (PVDF) and Tb–Dy–Fe alloy (Terfenol-D)/PVDF particulate composite layers, prepared by a simple hot-molding technique, are reported. In the laminated composites, the polymer PVDF is used just as a matrix binder. Our results demonstrate that the three-phase laminated composites exhibit remarkable magnetoelectric response especially at high frequency where an electromechanical resonance appears. The maximum magnetoelectric sensitivity of the laminated composites is as high as over 3000 mV/cm Oe at the resonance frequency of around 100 kHz.
High efficiency low operating voltage polymer light-emitting diodes with aluminum cathode
Authors: Deng X. Y. , Lau W. M. , Wong K. Y. , Low K. H. , Chow H. F. , Cao Y.
Published: April 2004

By blending poly(ethylene glycol) (PEG) into an electroluminescence (EL) polymer, significantly enhanced EL efficiency in a polymer light-emitting diode (PLED) with aluminum electrode was achieved. An orange-color-emitting PLED with 10 wt % PEG blending achieved device efficiencies exceeding 2.6 cd/A for a wide range of bias voltage, which is more than two orders of magnitude higher than that of a similar PLED without the PEG blending. The enhanced efficiency was a result of the reduction of electron injection barrier height at the cathode–polymer interface. It is believed that interfacial interaction that is specific to Al plays an important role in the enhancement mechanism.
Halogenated Terpenoids. XXIX The 1-Bromo 1-Bromomethyl Cyclohexyl System
Authors: Brecknell Douglas J. , Carman Raymond M. , Edwards Ross A. , Hansford Karl A. , Karoli Tomislav , Robinson Ward T.
Published: April 2004

Bromination of methylene groups exocyclic to cyclohexyl systems normally
affords two isomeric products; the axial 1-bromo equatorial 1-bromomethyl
compound and the axial 1-bromomethyl equatorial 1-bromo derivative. Free
energy differences between these two isomers, and the conformations adopted by
the axial 1-bromomethyl group, have been explored by n.m.r. spectroscopy, by
X-ray crystallography and by MM3 calculations. Evidence is presented to show
that the ax-bromomethyl group exists primarily as those
rotamers which site the bromine atom synclinal to the vicinal bromine. The
A value for a bromomethyl group in this system is then
similar to that of an unsubstituted methyl group.
Iodination of Thallium(I) Salts of Phenols
Authors: Cambie Richard C. , Larsen David S. , Rutledge Peter S. , Woodgate Paul D.
Published: April 2004

The iodination of thallium(I) salts of phenols is examined and the results are
compared with those of the selective ortho-iodinating
reagent thallium(I) acetate-iodine.
Fascin-mediated propulsion of Listeria monocytogenes independent of frequent nucleation by the Arp2/3 complex
Authors: Brieher William M. , Coughlin Margaret , Mitchison Timothy J.
Published: April 2004

Actin-dependent propulsion of Listeria monocytogenes is thought to require frequent nucleation of actin polymerization by the Arp2/3 complex. We demonstrate that L. monocytogenes motility can be separated into an Arp2/3-dependent nucleation phase and an Arp2/3-independent elongation phase. Elongation-based propulsion requires a unique set of biochemical factors in addition to those required for Arp2/3-dependent motility. We isolated fascin from brain extracts as the only soluble factor required in addition to actin during the elongation phase for this type of movement. The nucleation reaction assembles a comet tail of branched actin filaments directly behind the bacterium. The elongation-based reaction generates a hollow cylinder of parallel bundles that attach along the sides of the bacterium. Bacteria move faster in the elongation reaction than in the presence of Arp2/3, and the rate is limited by the concentration of G-actin. The biochemical and structural differences between the two motility reactions imply that each operates through distinct biochemical and biophysical mechanisms.
Mesenchymal–epithelial interactions in the skin
Authors: Yamaguchi Yuji , Itami Satoshi , Watabe Hidenori , Yasumoto Ken-ichi , Abdel-Malek Zalfa A. , Kubo Tateki , Rouzaud François , Tanemura Atsushi , Yoshikawa Kunihiko , Hearing Vincent J.
Published: April 2004

We investigated whether or not the topographic regulation of melanocyte differentiation is determined by mesenchymal–epithelial interactions via fibroblast-derived factors. The melanocyte density in palmoplantar human skin (i.e., skin on the palms and the soles) is five times lower than that found in nonpalmoplantar sites. Palmoplantar fibroblasts significantly suppressed the growth and pigmentation of melanocytes compared with nonpalmoplantar fibroblasts. Using cDNA microarray analysis, fibroblasts derived from palmoplantar skin expressed high levels of dickkopf 1 (DKK1; an inhibitor of the canonical Wnt signaling pathway), whereas nonpalmoplantar fibroblasts expressed higher levels of DKK3. Transfection studies revealed that DKK1 decreased melanocyte function, probably through β-catenin–mediated regulation of microphthalmia-associated transcription factor activity, which in turn modulates the growth and differentiation of melanocytes. Thus, our results provide a basis to explain why skin on the palms and the soles is generally hypopigmented compared with other areas of the body, and might explain why melanocytes stop migrating in the palmoplantar area during human embryogenesis.
Calcium Regulation of Single Ryanodine Receptor Channel Gating Analyzed Using HMM/MCMC Statistical Methods
Authors: Rosales Rafael A. , Fill Michael , Escobar Ariel L.
Published: April 2004

Type-II ryanodine receptor channels (RYRs) play a fundamental role in intracellular Ca2+ dynamics in heart. The processes of activation, inactivation, and regulation of these channels have been the subject of intensive research and the focus of recent debates. Typically, approaches to understand these processes involve statistical analysis of single RYRs, involving signal restoration, model estimation, and selection. These tasks are usually performed by following rather phenomenological criteria that turn models into self-fulfilling prophecies. Here, a thorough statistical treatment is applied by modeling single RYRs using aggregated hidden Markov models. Inferences are made using Bayesian statistics and stochastic search methods known as Markov chain Monte Carlo. These methods allow extension of the temporal resolution of the analysis far beyond the limits of previous approaches and provide a direct measure of the uncertainties associated with every estimation step, together with a direct assessment of why and where a particular model fails. Analyses of single RYRs at several Ca2+ concentrations are made by considering 16 models, some of them previously reported in the literature. Results clearly show that single RYRs have Ca2+-dependent gating modes. Moreover, our results demonstrate that single RYRs responding to a sudden change in Ca2+ display adaptation kinetics. Interestingly, best ranked models predict microscopic reversibility when monovalent cations are used as the main permeating species. Finally, the extended bandwidth revealed the existence of novel fast buzz-mode at low Ca2+ concentrations.
Modulation of the Voltage Sensor of L-type Ca2+ Channels by Intracellular Ca2+
Authors: Isaev Dmytro , Solt Karisa , Gurtovaya Oksana , Reeves John P. , Shirokov Roman
Published: April 2004

Both intracellular calcium and transmembrane voltage cause inactivation, or spontaneous closure, of L-type (CaV1.2) calcium channels. Here we show that long-lasting elevations of intracellular calcium to the concentrations that are expected to be near an open channel (≥100 μM) completely and reversibly blocked calcium current through L-type channels. Although charge movements associated with the opening (ON) motion of the channel's voltage sensor were not altered by high calcium, the closing (OFF) transition was impeded. In two-pulse experiments, the blockade of calcium current and the reduction of gating charge movements available for the second pulse developed in parallel during calcium load. The effect depended steeply on voltage and occurred only after a third of the total gating charge had moved. Based on that, we conclude that the calcium binding site is located either in the channel's central cavity behind the voltage-dependent gate, or it is formed de novo during depolarization through voltage-dependent rearrangements just preceding the opening of the gate. The reduction of the OFF charge was due to the negative shift in the voltage dependence of charge movement, as previously observed for voltage-dependent inactivation. Elevation of intracellular calcium concentration from ∼0.1 to 100–300 μM sped up the conversion of the gating charge into the negatively distributed mode 10–100-fold. Since the “IQ-AA” mutant with disabled calcium/calmodulin regulation of inactivation was affected by intracellular calcium similarly to the wild-type, calcium/calmodulin binding to the “IQ” motif apparently is not involved in the observed changes of voltage-dependent gating. Although calcium influx through the wild-type open channels does not cause a detectable negative shift in the voltage dependence of their charge movement, the shift was readily observable in the Δ1733 carboxyl terminus deletion mutant, which produces fewer nonconducting channels. We propose that the opening movement of the voltage sensor exposes a novel calcium binding site that mediates inactivation.
On the divergence of the Rogers-Ramanujan continued fraction on the unit circle
Authors: Bowman Douglas , Mc Laughlin James
Published: April 2004

This paper studies ordinary and general convergence of the Rogers-Ramanujan continued fraction. Let the continued fraction expansion of any irrational number

t
∈
(
0
,
1
)

t \in (0,1)

be denoted by

[
0
,

e

1

(
t
)
,

e

2

(
t
)
,
⋯
]

[0,e_{1}(t),e_{2}(t),\cdots ]

and let the

i
i

-th convergent of this continued fraction expansion be denoted by

c

i

(
t
)

/

d

i

(
t
)

c_{i}(t)/d_{i}(t)

. Let
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper S equals StartSet t element-of left-parenthesis 0 comma 1 right-parenthesis colon e Subscript i plus 1 Baseline left-parenthesis t right-parenthesis greater-than-or-equal-to phi Superscript d Super Subscript i Superscript left-parenthesis t right-parenthesis Baseline infinitely often EndSet comma">

S
=
{
t
∈
(
0
,
1
)
:

e

i
+
1

(
t
)
≥

ϕ

d

i

(
t
)

 infinitely often
}
,

S=\{t \in (0,1): e_{i+1}(t) \geq \phi ^{d_{i}(t)} \text { infinitely often}\},

\]
where

ϕ
=
(

5

+
1
)

/

2

\phi = (\sqrt {5}+1)/2

. Let

Y

S

=
{
exp
⁡
(
2
π
i
t
)
:
t
∈
S
}

Y_{S} =\{\exp (2 \pi i t): t \in S \}

. It is shown that if

y
∈

Y

S

y \in Y_{S}

, then the Rogers-Ramanujan continued fraction

R
(
y
)

R(y)

diverges at

y
y

.

S
S

is an uncountable set of measure zero. It is also shown that there is an uncountable set of points

G
⊂

Y

S

G \subset Y_{S}

such that if

y
∈
G

y \in G

, then

R
(
y
)

R(y)

does not converge generally. It is further shown that

R
(
y
)

R(y)

does not converge generally for

|

y

|

>
1

|y| > 1

. However we show that

R
(
y
)

R(y)

does converge generally if

y
y

is a primitive

5
m

5m

-th root of unity, for some

m
∈

N

m \in \mathbb {N}

. Combining this result with a theorem of I. Schur then gives that the continued fraction converges generally at all roots of unity.
The ∀∃-theory of ℛ(≤,∨,∧) is undecidable
Authors: Miller Russell , Nies Andre , Shore Richard
Published: April 2004

The three quantifier theory of

(

R

,

≤

T

)

(\mathcal {R},\leq _{T})

, the recursively enumerable degrees under Turing reducibility, was proven undecidable by Lempp, Nies and Slaman (1998). The two quantifier theory includes the lattice embedding problem and its decidability is a long-standing open question. A negative solution to this problem seems out of reach of the standard methods of interpretation of theories because the language is relational. We prove the undecidability of a fragment of the theory of

R

\mathcal {R}

that lies between the two and three quantifier theories with

≤

T

\leq _{T}

but includes function symbols. Theorem. The two quantifier theory of

(

R

,
≤
,
∨
,
∧
)

(\mathcal {R},\leq ,\vee ,\wedge )

, the r.e. degrees with Turing reducibility, supremum and infimum (taken to be any total function extending the infimum relation on

R

\mathcal {R}

) is undecidable. The same result holds for various lattices of ideals of

R

\mathcal {R}

which are natural extensions of

R

\mathcal {R}

preserving join and infimum when it exits.
A novel micro‐scale light‐sail and thin‐film beam‐generator
Authors: Bishop Forrest
Published: April 2004

“Microscale light sails” (MLS) are simultaneously manufactured and launched as a matter‐beam from a proposed Lunar facility. Lunar aluminum would be refined for the feedstock of this “thin film beam generator”. A battery of linear, aluminum‐vapor, rocket engines make up the first stage of a “laser cooled thermal beam”. After a supersonic expansion, the condensing sheets of AlI atoms undergo light‐force mediated cooling, guidance, and compression. The individual, partly condensed sheets are brought together at sufficiently low energy to form the core of the thin film. MLS‐swarms can become either the reaction‐mass for a deep space, beam‐propulsion transportation network, the constituents of an orbital space‐mirror or an interstellar, laser‐driven probe, or simply be used as raw building material for outer space structures. An articulation of the beam generator may manufacture solar cells and other kinds of thin‐films from space resources.
A method of separation of an aircraft motion on a roll and sideslip
Authors: Vershinin Y.A.
Published: April 2004

The requirements to maneuver a modern aircraft involve the development and realization of advanced control of a longitudinal and lateral aircraft motion. The manual control system for independent motion control of an aircraft on rolling and sideslip angles is studied. The system depends upon a real‐time measurement of air‐dynamic coefficients of the aircraft or requires the information from the tabulated parameters on all regimes of the aircraft motion. The exact parameters for all regimes of the aircraft motion cannot be obtained from a priori measurements either. In this paper, the solution for a decoupled motion of an aircraft is obtained in the class of non‐searching adaptive control systems with a reference model. The new algorithms developed in this paper achieve a decoupled motion with desirable dynamic precision even in conditions of high non‐stationary of parameters. The robustness of the control system to the interaction of subsystems is accomplished as well.
Error analysis and motion determination of a flight simulator
Authors: Yurt Sait N. , Ozkol İbrahim , Hajiyev Chingiz
Published: April 2004

A flight simulator must be designed to generate the correct acceleration cues, attitudes and vibrations to the flight compartment to provide an extra degree of realism for the pilots. Therefore, such a system, which has six degrees of freedom (dof), should enable to produce pitch, roll, yaw, heave, forward and lateral movement simultaneously. However, such a complex dynamic system can be modeled as a Stewart platform with pneumatic actuators, having six dof. During the simulations, on the position and orientation of moving platform, motion determination parameters and their absolute, relative errors and standard deviations are outlined. Simulation results, which are obtained, when closely examined reveal that the developed motion determination algorithm for the considered parallel dynamic mechanism is highly accurate. Additionally, a technique is introduced for the motion determination and its deviation from the given task.
Children's views of cooking and food preparation
Authors: Caraher Martin , Baker Heidi , Burns Maureen
Published: April 2004

A series of consultations with eight‐ and nine‐year‐old children in three schools in England and Wales are set out. The aim of the consultation was to determine how children view the world of cooking and food. A technique called draw and write was used to ascertain the views of the young people. The reports from the children in this survey display a disparate food culture. The Wales and Herefordshire schools showed a greater propensity for chips and fried foods as the mainstay of many meals, but this inclination was less evident in the London school. Overall the research suggests a lot of commonality, but also differences between the schools in terms of how food culture is interpreted geographically.
Confident, fearful and hopeless cooks
Authors: Stead Martine , Caraher Martin , Wrieden Wendy , Longbottom Patricia , Valentine Karen , Anderson Annie
Published: April 2004

One of the many barriers to a healthier diet in low‐income communities is a presumed lack of practical food skills. This article reports findings from exploratory qualitative research conducted with potential participants in a cooking skills intervention, in low income communities in Scotland. The research found widely varying levels of skill and confidence regarding cooking, supported the need for a community‐based intervention approach, and demonstrated the importance of consumer research to inform the content of interventions. Challenges the view that low income communities lack skills, suggesting that food skills should be defined more broadly than “cooking from scratch”. Other barriers to healthy eating, such as poverty, food access and taste preferences, remain important.
Meat consumption and meat avoidance among young people
Authors: Beardsworth Alan , Bryman Alan
Published: April 2004

This paper reports the findings of an 11‐year longitudinal study of the food preferences of first‐year social science undergraduates at a UK university. Argues that this predominantly young and female response group constitutes a “critical case” that can be used to assess broader trends in meat consumption and meat avoidance. Relatively high levels of meat avoidance (in terms of reduced consumption or vegetarianism) were detected, although in recent years the trend appears to be away from avoidance and towards an increase in the reported inclination to eat meat. An attempt is made to interpret the findings of the study within the broader context of long‐term shifts in attitudes towards meat consumption in general, and towards beef consumption in particular.
The European Food Safety Authority
Authors: Shears Peter , Zollers Frances E. , Hurd Sandra N.
Published: April 2004

There have been several “food scares” in Europe and across the Atlantic in recent years. They have led to nationally orientated reaction – often in the face of otherwise apparently binding international commitments. This article is concerned with such events and the planning, development and emergence of an international food safety agency for the European Union, taking into account “enlargement” and certain transatlantic perspectives. Concludes that the appliance of science should supersede the politics of nation states and the desire for re‐election, while bearing in mind that this is an unlikely dream.
Report on the 23rd annual Charleston Conference 2003
Authors: Cassell Kay
Published: April 2004

This paper outlines some of the topics covered at the 2003 Charleston Conference, November 2003, whose theme was “Issues in book and serial acquisition: games people play”. Issues addressed were concerns about the cost of electronic resources and the need for digitization of library resources.
Lebanese television archives
Authors: Saade Gladys
Published: April 2004

Technological advances in the information and communication industry have changed many other sectors as well. Written, visual or oral, digital information is transmitted instantly, distributed around the world, stored, examined and sold. It thus acquires a commercial value that overlaps with the historical value of the information, which is a part of the collective memory of a country. This paper examines the information archives of Lebanese television stations from a technical and an intellectual point of view and discusses how they treat news and other television programmes and whether television information is considered a commercial product. It is argued that it is evident that an institution concerned with public interest (as opposed to commercial interests) looks after the conservation of the national patrimony and the collective memory, by forming a legal deposit system and respecting the authors' rights. Such an attitude could play a role in the frame of a national information policy.
Modular manufacturing: an alternative to improve the competitiveness in the clothing industry
Authors: Ariel Sarache Castro William , Cespón Castro Roberto , Ibarra Mirón Santiago , Alonso Martínez Pedro U.
Published: April 2004

The change that occurred in the last years in the manufacturing environment of the clothing industry has motivated the redesign, in many cases, of its organizational and productive structures. For the companies in this sector, every time it becomes more necessary to reach satisfactory levels of competitiveness, as it is the only way of remaining in the market. For this, the adoption and implementation of different strategies that act on several links of the supply chain are required. One of these key links is the production function. In this paper, the advantages of the “just‐in‐time” philosophy for the clothing industry are mentioned, and more specifically the ones of modular manufacturing. This is based on the authors experience in relation to its use in the clothing industry, showing its superiority over the traditional in‐line manufacturing.
Condensation in three‐layer waterproof breathable fabrics for clothing
Authors: Ren Y.J. , Ruckman J.E.
Published: April 2004

This paper investigates the behaviour of condensation in three‐layer waterproof breathable fabrics for clothing. An attempt has been made to consider water vapour transfer when condensation occurs within the three‐layer waterproof breathable fabrics based on the simultaneous heat and mass transfer theory developed by Motakef and El‐Maher and diffusion and condensation theory developed by Wijeysundera et al. According to the analysis made of existing theory, it is possible to model condensation within fabrics and laminates using the thermodynamic equations outlined in this paper, which can assist in predicting the performance of textiles and help to understand the comfort of performance clothing. It is noted that the condensation problem may be solved by changing some physical properties of a three‐layer waterproof breathable fabric. The water vapour transfer out of the fabric can be improved, and consequently the formation of condensation reduced, by decreasing the thickness of the waterproof membrane and outer layer fabric or by increasing the average diffusion coefficient of the outer layer and membrane. A decrease in the thickness of the lining could increase the water vapour transfer from the hot side to the interface between the dry‐wet regions, but this would also increase the condensation. Increasing the diffusion coefficient of the lining will also increase both water vapour transfer from the hot side and condensation.
Simulation of transonic flutter and active shockwave control
Authors: Djayapertapa L. , Allen C.B.
Published: April 2004

Transonic flutter and active flap control, in two dimensions, are simulated by coupling independent structural dynamic and inviscid aerodynamic models, in the time domain. A flight control system, to actively control the trailing edge flap motion, has also been incorporated and, since this requires perfect synchronisation of fluid, structure and control signal, the “strong” coupling approach is adopted. The computational method developed is used to perform transonic aeroelastic and aeroservoelastic calculations in the time domain, and used to compute stability (flutter) boundaries of 2D wing sections. Open and closed loop simulations show that active control can successfully suppress flutter and results in a significant increase in the allowable speed index in the transonic regime. It is also shown that active control is still effective when there is free‐play in the control surface hinge. Flowfield analysis is used to investigate the nature of flutter and active control, and the fundamental importance of shock wave motion in the vicinity of the flap is demonstrated.
Numerical simulation of inductively coupled plasma flows under chemical non‐equilibrium
Authors: Degrez Gérard , Vanden Abeele David , Barbante Paolo , Bottin Benot
Published: April 2004

This paper presents a detailed review of the numerical modeling of inductively coupled air plasmas under local thermodynamic equilibrium and under chemical non‐equilibrium. First, the physico‐chemical models are described, i.e. the thermodynamics, transport phenomena and chemical kinetics models. Particular attention is given to the correct modelling of ambipolar diffusion in multi‐component chemical non‐equilibrium plasmas. Then, the numerical aspects are discussed, i.e. the space discretization and iterative solution strategies. Finally, computed results are presented for the flow, temperature and chemical concentration fields in an air inductively coupled plasma torch. Calculations are performed assuming local thermodynamic equilibrium and under chemical non‐equilibrium, where two different finite‐rate chemistry models are used. Besides important non‐equilibrium effects, we observe significant demixing of oxygen and nitrogen nuclei, which occurs due to diffusion regardless of the degree of non‐equilibrium in the plasma.