bluuebunny/crossref_metadata_2025 huggingface dataset:
Generating thickness gradients of thin polymer films via flow coating
Authors: Stafford Christopher M. , Roskov Kristen E. , Epps Thomas H. , Fasolka Michael J.
Published: February 2006

Thickness is a governing factor in the behavior of films and coatings. To enable the high-throughput analysis of this parameter in polymer systems, we detail the design and operation of a “flow coater” device for fabricating continuous libraries of polymer film thickness over tailored ranges. Focusing on the production of model polystyrene film libraries, we thoroughly outline the performance of flow coating by varying critical factors including device geometry, device motion, and polymer solution parameters.
Analysis and performance of a parallel axis flatness measuring instrument
Authors: Marsh Eric , Schalcosky David , Couey Jeremiah , Vallance Ryan
Published: February 2006

This article describes the design, analysis, and performance of a flatness inspection instrument to measure workpieces with up to 1mm departure from flatness. The instrument uses two air bearing spindles arranged with parallel axes to simultaneously rotate a workpiece and slowly pass a capacitance probe over the spinning surface. Capacitance probes offer user-selectable sensitivity to provide multiple combinations of measurement range and resolution. In tests with a high sensitivity probe, the instrument demonstrated measurement repeatability of 25nm on a ∅75mm workpiece. This article presents a complete homogeneous transformation matrix analysis of the propagation of errors into the measurement as well as sample measurements on diamond turned workpieces.
Explicitly correlated local second-order perturbation theory with a frozen geminal correlation factor
Authors: Manby Frederick R. , Werner Hans-Joachim , Adler Thomas B. , May Andrew J.
Published: February 2006

The recently introduced MP2-R12∕2*A(loc) and LMP2-R12∕2*A(loc) methods are modified to use a short-range correlation factor expanded as a fixed linear combination of Gaussian geminals. Density fitting is used to reduce the effort for integral evaluation, and local approximations are introduced to improve the scaling of the computational resources with molecular size. The MP2-F12∕2*A(loc) correlation energies converge very rapidly with respect to the atomic orbital basis set size. Already with the aug-cc-pVTZ basis the correlation energies computed for a set of 21 small molecules are found to be within 0.5% of the MP2 basis set limit. Furthermore the short-range correlation factor leads to an improved convergence of the resolution of the identity, and eliminates problems with long-range errors in density fitting caused by the linear r12 factor. The DF-LMP2-F12∕2*A(loc) method is applied to compute second-order correlation energies for molecules with up to 49 atoms and more than 1600 basis functions.
Potential energy surface, van der Waals motions, and vibronic transitions in phenol-argon complex
Authors: Makarewicz Jan
Published: February 2006

The structure and intermolecular vibrational energy levels of the phenol-Ar complex are calculated from its potential energy surface. This surface is constructed from a large set of the interaction energy values computed using second-order Møller-Plesset perturbation theory with the augmented correlation consistent polarized valence double-ζ basis set. The global minimum in the potential energy surface corresponds to a cluster structure with Ar located over the geometric center of the phenol ring at a distance of 3.510Å and shifted by 0.1355Å towards oxygen. The calculated dissociation energy of 371cm−1 is in accordance with the experiment. Additional local minima higher in energy are with Ar placed in the phenol plane. However, they are too shallow to form the bound states corresponding to planar isomers. The deformation of the potential energy surface shape, created by the interaction of Ar with the phenolic oxygen, is responsible for a pronounced intermode mixing. As a result, a set of hybrid stretching-bending states appears which cannot be described in terms of the standard models. The intermode coupling is reflected in the vibronic structure of the S1-S0 electronic transition. The intensities of the vibronic bands are calculated from the electronic transition dipole moment surfaces determined using the ab initio single-excitation configuration interaction method. They allow us to correct and complete the assignment of the spectra observed in phenol-Ar, as well as in the analogous complexes of phenol with Kr and Xe.
Dust acoustic solitary waves in a quantum plasma
Authors: Ali S. , Shukla P. K.
Published: February 2006

By employing one-dimensional quantum hydrodynamic (QHD) model for a three species quantum plasma, nonlinear properties of dust acoustic solitary waves are studied. For this purpose a Korteweg-de Vries (KdV) equation is derived, incorporating quantum corrections. The quantum mechanical effects are also examined numerically both on the profiles of the amplitude and the width of dust acoustic solitary waves. It is found that the amplitude remains constant but the width shrinks for different values of a dimensionless electron quantum parameter He=(Zd0ℏ2ωpd2)∕memdCd4, where Zd0 is the dust charge state, ℏ is the Planck constant divided by 2π, ωpd is the dust plasma frequency, me (md) is the electron (dust) mass, and Cd is the dust acoustic speed.
Multicentered valence electron effective potentials: A solution to the link atom problem for ground and excited electronic states
Authors: Slavíček Petr , Martínez Todd J.
Published: February 2006

We introduce a multicentered valence electron effective potential (MC-VEEP) description of functional groups which succeeds even in the context of excited electronic states. The MC-VEEP is formulated within the ansatz which is familiar for effective core potentials in quantum chemistry, and so can be easily incorporated in any quantum chemical calculation. By demanding that both occupied and virtual orbitals are described correctly on the MC-VEEP, we are able to ensure correct behavior even when the MC-VEEP borders an electronically excited region. However, the present formulation does require that the electrons represented by the MC-VEEP are primarily spectators and not directly participating in the electronic excitation. We point out the importance of separating the electrostatic and exchange-repulsion components of the MC-VEEP in order that interactions between the effective potential and other nuclei can be modeled correctly. We present a MC-VEEP for methyl radical with one active electron which is tested in several conjugated molecules. We discuss the use of the MC-VEEP as a solution to the “link atom” problem in hybrid quantum mechanical/molecular mechanical methods. We also discuss the limitations and further development of this approach.
Origin of blue-band emission from Mg-doped Al0.15Ga0.85N∕GaN superlattices
Authors: Lin T. Y. , Sheu Y. M. , Chen Y. F.
Published: February 2006

Investigation on the origin of blue luminescence from Mg-doped AlGaN∕GaN superlattices is presented. The edge emission of the blue band shows an optical anisotropy with a line symmetry along the c axis as probed by the polarized luminescence. The blue band inherently exhibits a metastable behavior as demonstrated by the dc and ac photoluminescence measurements and the metastable behavior can be enhanced by thermal treatment. Our results establish that the underlying microstructure responsible for the blue luminescence in Mg-doped AlGaN∕GaN SLs arises from the transitions involved in the threading structures decorated with Mg impurities/or other defects.
Theoretical model of interface trap density using the spread of the differential capacitance characteristics in scanning capacitance microscopy measurements
Authors: Wong K. M. , Chim W. K.
Published: February 2006

In this letter, we propose a theoretical model for the calculation of interface trap density (Dit) in a metal-oxide-semiconductor structure using data from scanning capacitance microscopy (SCM) measurements. The model is based on the correlation of Dit with the change in the full width at half maximum of the SCM differential capacitance (dC∕dV) characteristics. The good agreement between the calculated Dit values from the SCM theoretical model and the experimental midgap Dit values obtained from conductance measurements shows the validity of the proposed model. The model opens up possibilities for obtaining the spatial distribution (with nanometers resolution) of interfacial traps on a device using SCM measurements.
Improved efficiency for white organic light-emitting devices based on phosphor sensitized fluorescence
Authors: Cheng Gang , Zhang Yingfang , Zhao Yi , Liu Shiyong , Ma Yuguang
Published: February 2006

Efficiency of white organic light-emitting devices (WOLEDs) based on phosphor sensitized fluorescence is improved by using an unusual device structure, in which an undoped blue emissive layer is sandwiched between two phosphorescent doped ones. This blue emissive layer blocks a triplet-triplet energy transfer between the two phosphorescent emissive layers, leading to balanced emissions of blue, green, yellow, and red. Thus, an efficient WOLED with a maximum luminous efficiency of 13.8cd∕A, a maximum power efficiency of 8.0lm∕W, a color rendering index of 79, and Commission Internationale de L’Eclairage coordinates of (0.33, 0.35) is achieved.
Direct Al cathode layer sputtering on LiF∕Alq3 using facing target sputtering with a mixture of Ar and Kr
Authors: Kim Han-Ki , Kim Sang-Woo , Lee Kyu-Sung , Kim K. H.
Published: February 2006

Using facing target sputtering (FTS) with a mixture of Ar and Kr, direct Al cathode sputtering on LiF∕Alq3 layers was accomplished without the need for a protective layer against plasma damage. Organic light emitting diodes (OLEDs) with a directly sputtered Al cathode in a mixture of Ar and Kr showed a much lower leakage current density (∼1×10−5mA∕cm2 at −6V) than those (∼1×10−1mA∕cm2 at −6V) of OLEDs with an Al cathode prepared by FTS or dc sputtering in a pure Ar ambient. This indicates that the bombardment of energetic particles is effectively restricted by mixing a heavy noble gas. Based on the current-voltage curve for the OLED, a possible mechanism is proposed to explain the effect of a heavy noble gas mixture on electrical properties of OLEDs for direct Al cathode sputtering by FTS.
Alkyl chain length dependent mobility of organic field-effect transistors based on thienyl-furan oligomers determined by the transfer line method
Authors: Minari Takeo , Miyata Yasuo , Terayama Miki , Nemoto Takashi , Nishinaga Tohru , Komatsu Koichi , Isoda Seiji
Published: February 2006

Organic field-effect transistors are fabricated using oligomers composed of alternating connected thiophene and furan, and those having alkyl substituents at both ends of the molecules. The mobilities are determined by the transfer line method to correct for the effect of source/drain parasitic resistance. A mobility of 0.042cm2∕Vs is achieved for a thienyl-furan oligomer composed of five heterocycles and having hexyl groups at the terminal rings. The mobility of the oligomers strongly depends on the length of the π-conjugated chain and the alkyl chain substituent at both ends, attributable to the specific structural and morphological properties of the vacuum-deposited films.
Significance of solubility product in the solution growth of Pb1−xMxS (M=Fe, Co, Cd, and Mn) nanoparticle films
Authors: Joshi Rakesh K.
Published: February 2006

A model is proposed to explain the observed decrease of average grain size with an increase of Fe concentration in the Pb1−xFexS (0.25⩽x⩽0.75) and Co concentration in the Pb1−xCoxS (0.15⩽x⩽0.35) nanoparticle films. Higher solubility product for MS (M=Fe and Co) as compared to PbS is observed to be responsible for the decrease of grain size with an increase of M concentration in the films. The model was found true for Pb1−xCdxS (0.45⩽x⩽0.85) and Pb1−xMnxS (0.03⩽x⩽0.37) films.
Quantum dissipation and broadening mechanisms due to electron-phonon interactions in self-formed InGaN quantum dots
Authors: Xu S. J. , Li G. Q. , Wang Y. J. , Zhao Y. , Chen G. H. , Zhao D. G. , Zhu J. J. , Yang H. , Yu D. P. , Wang J. N.
Published: February 2006

Quantum dissipation and broadening mechanisms in Si-doped InGaN quantum dots are studied via the photoluminescence technique. It is found that the dissipative thermal bath that embeds the quantum dots plays an important role in the photon emission processes. Observed spontaneous emission spectra are modeled with the multimode Brownian oscillator model achieving an excellent agreement between experiment and theory for a wide temperature range. The dimensionless Huang-Rhys factor characterizing the strength of electron-LO-phonon coupling and damping constant accounting for the LO-phonon-bath interaction strength are found to be ∼0.2 and 200cm−1, respectively, for the InGaN QDs.
Mid-infrared hole-intersubband electroluminescence in carbon-doped GaAs∕AlGaAs quantum cascade structures
Authors: Malis Oana , Pfeiffer Loren N. , West Kenneth W. , Sergent A. Michael , Gmachl Claire
Published: February 2006

Mid-infrared electroluminescence from carbon-doped GaAs∕AlGaAs quantum cascade structures was observed and studied to determine the prospects of hole intersubband transitions for possible use in light emitting devices. The luminescence spectra exhibit a complex three-peak structure consistent with two heavy-to-heavy hole transitions and thermal emission. The hole transition energies in emission are in agreement with corresponding absorption and photocurrent energies, but typically 17% smaller than expected from calculations of a six-band k∙p model. The upper-level lifetime was estimated to be 0.4ps, in agreement with simple calculations considering approximations of the heavy-hole effective masses.
Inclusion of nanosized silicon grains in hydrogenated protocrystalline silicon multilayers and its relation to stability
Authors: Myong Seung Yeop , Kwon Seong Won , Lim Koeng Su , Kondo Michio , Konagai Makoto
Published: February 2006

Photoluminescence and Fourier transform infrared spectroscopy measured at room temperature produce strong evidence that nanosized silicon (nc-Si) grains embedded in hydrogenated protocrystalline silicon (i-pc-Si:H) multilayers. Thus, we propose the structure of the i-pc-Si:H multilayer possessing isolated nc-Si grains and their wrapping layers with a high hydrogen concentration embedded in highly hydrogen-diluted sublayers. The isolated nc-Si grains may act as radiative recombination centers of photoexcited carriers, and hence suppress the photocreation of dangling bonds caused by the nonradiative recombination in amorphous silicon matrix. Because of the repeatedly layered structure, the i-pc-Si:H multilayers have a fast light-induced metastability with a low degradation.
Impact of substrate temperature on the incorporation of carbon-related defects and mechanism for semi-insulating behavior in GaN grown by molecular beam epitaxy
Authors: Armstrong A. , Poblenz C. , Green D. S. , Mishra U. K. , Speck J. S. , Ringel S. A.
Published: February 2006

The electrical conductivity and deep level spectrum of GaN grown by molecular beam epitaxy and codoped with carbon and silicon were investigated for substrate temperatures Ts of 650 and 720°C as a function relative carbon and silicon doping levels. With sufficiently high carbon doping, semi-insulating behavior was observed for films grown at both temperatures, and growth at Ts=720°C enhanced the carbon compensation ratio. Similar carbon-related band gap states were observed via deep level optical spectroscopy for films grown at both substrate temperatures. Due to the semi-insulating nature of the films, a lighted capacitance-voltage technique was required to determine individual deep level concentrations. Carbon-related band gap states underwent substantial redistribution between deep level and shallow acceptor configurations with change in Ts. In light of a Ts dependence for the preferential site of carbon incorporation, a model of semi-insulating behavior in terms of carbon impurity state incorporation mediated by substrate temperature is proposed.
Hydrogenated amorphous silicon ultraviolet sensor for deoxyribonucleic acid analysis
Authors: de Cesare G. , Caputo D. , Nascetti A. , Guiducci C. , Riccò B.
Published: February 2006

In this letter, we show the results achieved using a hydrogenated amorphous silicon photosensor for a “label-free” deoxyribonucleic acid (DNA) analysis based on the measurements of the absorbance in the ultraviolet range. The optimization of the sensor structure allowed us to bring the detection limit for a 30-mer DNA sample down to 1nM×cm, limited by the experimental setup. Taking advantage of the hypochromic effect, we also demonstrated the detection of single- and double-stranded DNA molecules in a melting experiment. From the noise characterization of our setup, we estimated the minimum DNA absorbance required to detect the occurrence of a hybridization/separation process to be below 10−3.
Very-thin-perylene-crystal-based electroluminescent devices
Authors: Yee Kok Wei , Yokoyama Masaaki , Hiramoto Masahiro
Published: February 2006

Sandwich-type cells have been fabricated using very thin (5μm) perylene single crystals, obtained by slicing the crystal, embedded in the epoxy resin, using a microtome. Orange electroluminescence (EL) was reproducibly observed. An EL intensity of 3.3mWcm−2 and a current quantum efficiency of 4% were obtained. The present device has the configuration of a Fabry-Pérot resonator and is suitable for low-temperature operation.
Mean barrier height of Pd Schottky contacts on ZnO thin films
Authors: von Wenckstern Holger , Biehne Gisela , Rahman R. Abdel , Hochmuth Holger , Lorenz Michael , Grundmann Marius
Published: February 2006

We have investigated the temperature dependence of the barrier height of high-quality Pd Schottky contacts on (0001)-oriented ZnO thin films by temperature-dependent current-voltage and capacitance-voltage (CV) measurements. The films have been grown by pulsed-laser deposition. The effective Schottky barrier height ΦB,eff deduced from the current-voltage measurements was evaluated by considering a Gaussian barrier height distribution with a standard deviation σ around a mean barrier height ΦB,m. We determined ΦB,m=(1.16±0.04)eV which agrees well with the value of 1.14eV determined by CV measurements. The standard deviation is determined to be (134±10)meV.
Production of self-aligned metal nanocolumns embedded in an oxide matrix film
Authors: Margueritat Jérémie , Gonzalo Jose , Afonso Carmen N. , Ortiz M. Isabel , Ballesteros Carmen
Published: February 2006

Self-aligned silver nanocolumns embedded in amorphous Al2O3 matrix are produced by alternate pulsed laser deposition at room temperature in a single step process. The morphology and the spatial distribution have been investigated by standard, high resolution, and scanning transmission electron microscopy. Polycrystalline nanocolumns having diameters close to 3nm and heights up to 7nm are all oriented perpendicular to the substrate surface. The self-alignment of the nanocolumns is the consequence of the deposition of consecutive layers of Ag nanoparticles using the first layer as template for the ordered growth of the nanocolumns. Control over the density, diameter and height of the nanocolumns is achievable by tailoring the deposition sequence.
High-performance Ag0.8Pb18+xSbTe20 thermoelectric bulk materials fabricated by mechanical alloying and spark plasma sintering
Authors: Wang Heng , Li Jing-Feng , Nan Ce-Wen , Zhou Min , Liu Weishu , Zhang Bo-Ping , Kita Takuji
Published: February 2006

Polycrystalline AgnPbmSbTem+2n thermoelectric materials, whose compositions can be described as Ag0.8Pb18+xSbTe20 were prepared using a combined process of mechanical alloying and spark plasma sintering. Electric properties of the sintered samples with different Pb contents were measured from room temperature to 700K. The maximum power factor of 1.766mW∕mK2 was obtained at 673K for the Ag0.8Pb22SbTe20 sample, which corresponds to a high dimensionless figure of merit, ZT=1.37. This best composition is different from that reported before.
The Control of Fixation Duration in Visual Search
Authors: Greene Harold H
Published: February 2006

A study is reported how fixation durations are affected as observers voluntarily use information in the visual environment to direct saccades in search of a target. In experiments with direction-coded displays, search fixation durations for correct and incorrectly directed saccades were comparable during image-driven/bottom-up search. In contrast, for knowledge-driven search, the relationship depended on peripheral preview. With ample access to peripheral preview, search fixation durations preceding correct saccades were shorter than those preceding incorrectly directed saccades. However, they were longer when preview was constrained by a gaze-contingent moving window. Fixation control was modeled as sigmoid functions.
Visual Motion Interferes with Tactile Motion Perception
Authors: Craig James C
Published: February 2006

Previous studies have demonstrated that visual apparent motion can alter the judgment of auditory apparent motion. We investigated the effect of visual apparent motion on judgments of the direction of tactile apparent motion. When visual motion was presented at the same time as, but in a direction opposite to, tactile motion, accuracy in judging the direction of tactile apparent motion was substantially reduced. This reduction in performance is referred to as ‘the congruency effect’. Similar effects were observed when the visual display was placed either near to the tactile display or at some distance from the tactile display (experiment 1). In experiment 2, the relative alignment between the visual and tactile directions of motion was varied. The size of the congruency effect was similar at 0° and 45° alignments but much reduced at a 90° alignment. In experiment 3, subjects made confidence ratings of their judgments of the direction of the tactile motion. The results indicated that the congruency effect was not due to subjects being unsure of the direction of motion and being forced to guess. In experiment 4, static visual stimuli were shown to have no effect on the judgments of direction of the tactile stimuli. The extent to which the congruency effect reflects capture effects and is the result of perceptual versus post-perceptual processes is discussed.
Are People with High and Low Mental Rotation Abilities Differently Susceptible to the Alignment Effect?
Authors: Pazzaglia Francesca , De Beni Rossana
Published: February 2006

We investigated whether the alignment effect (Levine et al, 1982 Journal of Experimental Psychology: General111 157–175) is influenced by mental rotation abilities. In two experiments, groups of undergraduate students with high and low performance in mental rotation tasks were required to study either schematic (experiment 1) or more complex (experiment 2) maps, and to perform a number of pointing tasks adopting a perspective which could be aligned, misaligned (45°, 135°), or counteraligned (180°) with the perspective assumed during learning. Cognitive styles in spatial representation have also been considered. Results of experiment 1 show that people with low performance in mental rotation tasks prefer to adopt a representation of space focused more on landmarks. Their performance in the pointing tasks depends on the alignment conditions, with more errors in the counteraligned condition followed by the two misaligned and aligned ones. In contrast to this, high-ability mental rotators prefer survey and route spatial representations and are affected only by the aligned and non-aligned conditions. In the second experiment, practice was studied as a function of mental rotation and alignment. The group high in mental rotation ability was found to be free from the alignment effect in the pointing tasks performed after the final of four learning phases.
Learning from the historical failure of farm management models to aid management practice. Part 1. The rise and demise of theoretical models of farm economics
Authors: McCown R. L. , Brennan L. E. , Parton K. A.
Published: February 2006

A potential source of lessons for agricultural modellers aspiring to influence farm decision making is the historical experience of agricultural economists in the field, variously termed ‘Farm Management Research’ or ‘Farm Management’. Although the histories of Farm Management in the USA and in Australia differ significantly, in both cases the field was originally characterised by pragmatic on-farm research by agricultural scientists and later taken over by agricultural economists committed to theory-based economic analysis to enable rational planning and decision making. But in both countries, it became painfully evident to reflective participants that model-based Farm Management was not proving relevant to practical managers of farms. An insightful few went further to conclude not just that theoretical models of practice had not been relevant but that they could not be relevant, and since the late 1970s, the field has been in crisis.
In this series of 2 papers, we seek insights that might explain this extraordinary ‘market’ failure of models that generate theoretical best practice as a basis for intervention. As an ‘experiment’, the history of Farm Management is enriched by the discontinuity between 2 ‘eras’ characterised by 2 contrasting intervention approaches, an ‘early’ interactive and pragmatic era and a ‘late’ academic and theoretical era. In this first paper, after a brief history of the early pragmatic era and the ‘take-over’ by economic theorists, we analyse the ‘crisis of relevance’ that led to demise, relying heavily on the remarkable intellectual journey of John Dillon, the first Professor of Farm Management in Australia who turned from being elder economic theoretician to pioneer philosopher of pragmatic Farming Systems Research.
The significant turn to Farming Systems Research by disillusioned Farm Management economists in the 1980s was preceded by a turn to another systems approach 2 decades earlier, that of agricultural systems modelling. Learning from the autecology of these significant systems efforts to influence the management of farms is the aim of the second paper in this series.
Effect of blackleg and sclerotinia stem rot on canola yield in the high rainfall zone of southern New South Wales, Australia
Authors: Kirkegaard John A , Robertson Michael J. , Hamblin Peter , Sprague Susan J.
Published: February 2006

Canola (Brassica napus) yields have been declining in the medium–high rainfall (550–650 mm) areas of southern NSW during the 1990s. This decline is not related to seasonal conditions and is not evident in wheat. Leading growers and consultants suspect that increasing levels of the diseases blackleg, caused by Leptosphaeria maculans, and sclerotinia stem rot, caused by Sclerotinia sclerotiorum, may be responsible. We investigated the effect of these diseases on otherwise well-managed canola crops at 2 sites in southern NSW from 2001 to 2003. Blackleg was present at both sites in all 3 years, with 8–10% of plants of variety Rainbow lodged in the untreated plots at Galong in all years, and 1–10% at Wallendbeen. Sclerotinia stem rot was predominately confined to 2001 when 7–42% of plants were infected in the untreated plots at the sites. Individually, or in combination, the diseases caused significant yield losses at both sites in every year of the study, ranging from 0.39 t/ha to 1.54 t/ha. These findings suggest that for each 1% reduction in the incidence of blackleg lodging, yield was increased by 5%, whereas each 1% reduction in plants infected with sclerotinia stem rot increased yield by 1.3%. The ability of the crops to yield to their simulated water and N-limited potential when these diseases were either absent or controlled, indicates that disease may be the key yield-limiting factor in the area. Cost-effective control strategies for both diseases are critical if canola is to remain an important and profitable break crop in the farming system in the high-rainfall zone of southern NSW.
A revision of Australian Trachymene (Apiaceae: Hydrocotyloideae)
Authors: Hart J. M. , Henwood M. J.
Published: February 2006

The current use of the name Trachymene Rudge was determined in the 1930s. However a comprehensive synonymy for the numerous published names in Trachymene has not previously been compiled. All Australian species of Trachymene are treated. A nomen novum, Trachymene leptophylla J.M.Hart, is provided for the illegitimate Trachymene filiformis Steenis. In addition, two new Australian species, Trachymene umbratica J.M.Hart and Trachymene thysanocarpa J.M.Hart, are described. A new combination: Trachymene composita var. robertsonii (Domin) J.M.Hart is made and range extensions for Trachymene oleracea subsp. sedimenta Rye, Trachymene bialata (Domin) B.L.Burtt and Trachymene rotundifolia (Benth.) Maconochie are recorded. Seven lectotypes are designated. Distribution maps and a key to all Australian species of Trachymene are provided.
Monitoring food and nutrient availability in a nationally representative sample of Bolivian households
Authors: Pérez-Cueto F.J. Armando , Naska Androniki , Monterrey Javier , Almanza-Lopez Magaly , Trichopoulou Antonia , Kolsteren Patrick
Published: February 2006

The study objective was to estimate food and nutrient availability in Bolivian households using data from the nationally representative under the Programme for the household surveys undertaken yearly from 1999 to 2002 Improvement of Surveys and the Measurement of Living Conditions in Latin America and the Caribbean (MECOVI). In the present study, we analysed data from four repeated, cross-sectional surveys and applied European Data Food Networking (DAFNE) methodology for post-harmonising the data. Raw data of 19 483 households in Bolivia (3035 in 1999, 4857 in 2000, 5845 in 2001 and 5746 in 2002) were retrieved from the databases of the national household surveys. Results showed that the Bolivian diet is characterised by higher availability of foods of plant origin (cereals, fruits, potatoes and vegetables). Meat, milk and their products follow in the dietary preferences of Bolivians. Disparities in food availability within the country were also observed. Rural households systematically recorded lower amounts of food available, in comparison with the urban ones. Households of higher social status recorded higher availability values for all food groups, except for potatoes and cereals. Findings suggest that Bolivian households of lower socio-economic status prefer energy-dense and cheaper food sources. We concluded the dietary and socio-demographic data collected in the MECOVI household surveys could serve nutrition surveillance purposes. In addition, the application of DAFNE methodology for post-harmonising the data allows both national and international comparisons.
Accuracy of food intake reporting in obese subjects with metabolic risk factors
Authors: Svendsen Mette , Tonstad Serena
Published: February 2006

The aim of the present study was to determine the accuracy of reported energy intake according to a food-frequency questionnaire (FFQ) and dietary records (DR) in obese subjects with metabolic syndrome risk factors. Subjects were twenty-three men and twenty-seven women with mean BMI of 35·7 (range 30·5–43·8) kg/m2 who participated in a dietary interview based on a FFQ and completed weighed DR. Total energy expenditure was measured with the doubly labelled water method. Total energy expenditure, measured RMR and physical activity level did not differ between under-reporters (50% of the sample) and non-under-reporters. Under-reporters had lower median intake of sweets, desserts and snacks than non-under-reporters (100 V.. 161g/d (P=0·0008) and 61 V.. 128g/d (P.=0·0002) according to the FFQ and DR, respectively). The DR also showed lower energy density (6·7 (sd 1·3) V 7·9 (sd 1·6) kJ/g; P=0·0064), lower intake of sugary drinks (0 V. 167g/d; P=0·0063) and higher scores for dietary restraint (9·0 (sd 5·0) V. 6·1 (sd 3·5); P=0·0285) in under-reporters. Energy density was associated with accuracy according to the FFQ (Spearman's rank correlation coefficient (RS) 0·406; P=0·0034) and the DR (RS 0·537; P<0·0001). In multivariate analysis, consumption of bread and sweets, desserts and snacks measured by the FFQ was positively associated with accuracy (I2adjusted 0·46 (95% CI 0·32, 0·70)). According to the DR, consumption of sweets, desserts and snacks was also associated with accuracy, as was dietary restraint (inversely) (I2adjusted 0·67 (95% CI 0·54, 0·83)). In obese subjects with metabolic risk factors, intake of sweets, desserts and snacks, bread and dietary restraint were determinants of reporting accuracy.
Assembling an intermediate filament network by dynamic cotranslation
Authors: Chang Lynne , Shav-Tal Yaron , Trcek Tatjana , Singer Robert H. , Goldman Robert D.
Published: February 2006

We have been able to observe the dynamic interactions between a specific messenger RNA (mRNA) and its protein product in vivo by studying the synthesis and assembly of peripherin intermediate filaments (IFs). The results show that peripherin mRNA-containing particles (messenger ribonucleoproteins [mRNPs]) move mainly along microtubules (MT). These mRNPs are translationally silent, initiating translation when they cease moving. Many peripherin mRNPs contain multiple mRNAs, possibly amplifying the total amount of protein synthesized within these “translation factories.” This mRNA clustering is dependent on MT, regulatory sequences within the RNA and the nascent protein. Peripherin is cotranslationally assembled into insoluble, nonfilamentous particles that are precursors to the long IF that form extensive cytoskeletal networks. The results show that the motility and targeting of peripherin mRNPs, their translational control, and the assembly of an IF cytoskeletal system are linked together in a process we have termed dynamic cotranslation.
Ca2+-Induced Ca2+ Release through Localized Ca2+ Uncaging in Smooth Muscle
Authors: Ji Guangju , Feldman Morris , Doran Robert , Zipfel Warren , Kotlikoff Michael I.
Published: February 2006

Ca2+-induced Ca2+ release (CICR) from the sarcoplasmic reticulum (SR) occurs in smooth muscle as spontaneous SR Ca2+ release or Ca2+ sparks and, in some spiking tissues, as Ca2+ release that is triggered by the activation of sarcolemmal Ca2+ channels. Both processes display spatial localization in that release occurs at a higher frequency at specific subcellular regions. We have used two-photon flash photolysis (TPFP) of caged Ca2+ (DMNP-EDTA) in Fluo-4–loaded urinary bladder smooth muscle cells to determine the extent to which spatially localized increases in Ca2+ activate SR release and to further understand the molecular and biophysical processes underlying CICR. TPFP resulted in localized Ca2+ release in the form of Ca2+ sparks and Ca2+ waves that were distinguishable from increases in Ca2+ associated with Ca2+ uncaging, unequivocally demonstrating that Ca2+ release occurs subsequent to a localized rise in [Ca2+]i. TPFP-triggered Ca2+ release was not constrained to a few discharge regions but could be activated at all areas of the cell, with release usually occurring at or within several microns of the site of photolysis. As expected, the process of CICR was dominated by ryanodine receptor (RYR) activity, as ryanodine abolished individual Ca2+ sparks and evoked release with different threshold and kinetics in FKBP12.6-null cells. However, TPFP CICR was not completely inhibited by ryanodine; Ca2+ release with distinct kinetic features occurred with a higher TPFP threshold in the presence of ryanodine. This high threshold release was blocked by xestospongin C, and the pharmacological sensitivity and kinetics were consistent with CICR release at high local [Ca2+]i through inositol trisphosphate (InsP3) receptors (InsP3Rs). We conclude that CICR activated by localized Ca2+ release bears essential similarities to those observed by the activation of ICa (i.e., major dependence on the type 2 RYR), that the release is not spatially constrained to a few specific subcellular regions, and that Ca2+ release through InsP3R can occur at high local [Ca2+]i.
Luteinizing Hormone Receptor Ectodomain Splice Variant Misroutes the Full-Length Receptor into a Subcompartment of the Endoplasmic Reticulum
Authors: Apaja Pirjo M. , Tuusa Jussi T. , Pietilä E. Maritta , Rajaniemi Hannu J. , Petäjä-Repo Ulla E.
Published: February 2006

The luteinizing hormone receptor (LHR) is a G protein–coupled receptor that is expressed in multiple RNA messenger forms. The common rat ectodomain splice variant is expressed concomitantly with the full-length LHR in tissues and is a truncated transcript corresponding to the partial ectodomain with a unique C-terminal end. Here we demonstrate that the variant alters the behavior of the full-length receptor by misrouting it away from the normal secretory pathway in human embryonic kidney 293 cells. The variant was expressed as two soluble forms of Mr52,000 and Mr54,000, but although the protein contains a cleavable signal sequence, no secretion to the medium was observed. Only a very small fraction of the protein was able to gain hormone-binding ability, suggesting that it is retained in the endoplasmic reticulum (ER) by its quality control due to misfolding. This was supported by the finding that the variant was found to interact with calnexin and calreticulin and accumulated together with these ER chaperones in a specialized juxtanuclear subcompartment of the ER. Only proteasomal blockade with lactacystin led to accumulation of the variant in the cytosol. Importantly, coexpression of the variant with the full-length LHR resulted in reduction in the number of receptors that were capable of hormone binding and were expressed at the cell surface and in targeting of immature receptors to the juxtanuclear ER subcompartment. Thus, the variant mediated misrouting of the newly synthesized full-length LHRs may provide a way to regulate the number of cell surface receptors.
The Mcp Element Mediates Stable Long-Range Chromosome–Chromosome Interactions inDrosophila
Authors: Vazquez Julio , Müller Martin , Pirrotta Vincenzo , Sedat John W.
Published: February 2006

Chromosome organization inside the nucleus is not random but rather is determined by a variety of factors, including interactions between chromosomes and nuclear components such as the nuclear envelope or nuclear matrix. Such interactions may be critical for proper nuclear organization, chromosome partitioning during cell division, and gene regulation. An important, but poorly documented subset, includes interactions between specific chromosomal regions. Interactions of this type are thought to be involved in long-range promoter regulation by distant enhancers or locus control regions and may underlie phenomena such as transvection. Here, we used an in vivo microscopy assay based on Lac Repressor/operator recognition to show that Mcp, a polycomb response element from the Drosophila bithorax complex, is able to mediate physical interaction between remote chromosomal regions. These interactions are tissue specific, can take place between multiple Mcp elements, and seem to be stable once established. We speculate that this ability to interact may be part of the mechanism through which Mcp mediates its regulatory function in the bithorax complex.
Changes in Properties of Substantia Gelatinosa Neurons after Surgical Incision in the Rat
Authors: Kawamata Mikito , Furue Hidemasa , Kozuka Yuji , Narimatsu Eichi , Yoshimura Megumu , Namiki Akiyoshi
Published: February 2006

Background

Noxious information through A delta and C afferent fibers is transmitted to substantia gelatinosa, a process that plays an important role in plastic changes of nociceptive processing in pathophysiological conditions. In this study, changes in properties of substantia gelatinosa neurons and their sensitivity to systemic administration of lidocaine after surgical incision were investigated using the in vivo patch-clamp technique.

Methods

Under urethane anesthesia, in the current clamp mode, spontaneous activities and responses of substantia gelatinosa neurons to nonnoxious air-puff stimuli and noxious pinch stimuli were recorded before and after 1-cm-long incisions had been made in hairy skin of the hindquarters of rats. Systemic administration of lidocaine (2 mg/kg) was applied at 30 min after the incision.

Results

Stable recordings for 30 min or more after the incision were obtained from 18 substantia gelatinosa neurons that were classified as multireceptive (n = 8), nociceptive (n = 5), and subthreshold (n = 5) neurons. Action potential firing disappeared immediately after completion of the wound closure in most multireceptive and nociceptive neurons, and sustained spontaneous action potential firing was observed in 23% of these substantia gelatinosa neurons. Responsiveness of these substantia gelatinosa neurons, but not that of subthreshold neurons, increased after the incision. Systemic administration of lidocaine suppressed spontaneous firings of action potentials of the substantia gelatinosa neurons and reversed the increased responsiveness of the neurons.

Conclusions

The results suggest that (1) changes in properties of substantia gelatinosa neurons after incision vary depending on the classification of substantia gelatinosa neurons and (2) systemic administration of lidocaine can reverse increased responsiveness of substantia gelatinosa neurons after incision injury.
Cortical Processing of Complex Auditory Stimuli during Alterations of Consciousness with the General Anesthetic Propofol
Authors: Plourde Gilles , Belin Pascal , Chartrand Daniel , Fiset Pierre , Backman Steven B. , Xie Guoming , Zatorre Robert J.
Published: February 2006

Background

The extent to which complex auditory stimuli are processed and differentiated during general anesthesia is unknown. The authors used blood oxygenation level-dependent functional magnetic resonance imaging to examine the processing words (10 per period; compared with scrambled words) and nonspeech human vocal sounds (10 per period; compared with environmental sounds) during propofol anesthesia.

Methods

Seven healthy subjects were tested. Propofol was given by a computer-controlled pump to obtain stable plasma concentrations. Data were acquired during awake baseline, sedation (propofol concentration in arterial plasma: 0.64 +/- 0.13 microg/ml; mean +/- SD), general anesthesia (4.62 +/- 0.57 microg/ml), and recovery. Subjects were asked to memorize the words.

Results

During all periods including anesthesia, the sounds conditions combined elicited significantly greater activations than silence bilaterally in primary auditory cortices (Heschl gyrus) and adjacent regions within the planum temporale. During sedation and anesthesia, however, the magnitude of the activations was reduced by 40-50% (P < 0.05). Furthermore, anesthesia abolished voice-specific activations seen bilaterally in the superior temporal sulcus during the other periods as well as word-specific activations bilaterally in the Heschl gyrus, planum temporale, and superior temporal gyrus. However, scrambled words paradoxically elicited significantly more activation than normal words bilaterally in planum temporale during anesthesia. Recognition the next day occurred only for words presented during baseline plus recovery and was correlated (P < 0.01) with activity in right and left planum temporale.

Conclusions

The authors conclude that during anesthesia, the primary and association auditory cortices remain responsive to complex auditory stimuli, but in a nonspecific way such that the ability for higher-level analysis is lost.
Propofol Pharmacokinetics and Pharmacodynamics for Depth of Sedation in Nonventilated Infants after Major Craniofacial Surgery
Authors: Peeters Mariska Y. M. , Prins Sandra A. , Knibbe Catherijne A. J. , DeJongh Joost , van Schaik Ron H. N. , van Dijk Monique , van der Heiden Ilse P. , Tibboel Dick , Danhof Meindert
Published: February 2006

Background

To support safe and effective use of propofol in nonventilated children after major surgery, a model for propofol pharmacokinetics and pharmacodynamics is described.

Methods

After craniofacial surgery, 22 of the 44 evaluated infants (aged 3-17 months) in the pediatric intensive care unit received propofol (2-4 mg . kg-1 . h-1) during a median of 12.5 h, based on the COMFORT-Behavior score. COMFORT-Behavior scores and Bispectral Index values were recorded simultaneously. Population pharmacokinetic and pharmacodynamic modeling was performed using NONMEM V (GloboMax LLC, Hanover, MD).

Results

In the two-compartment model, body weight (median, 8.9 kg) was a significant covariate. Typical values were Cl = 0.70 . (BW/8.9)0.61 l/min, Vc = 18.8 l, Q = 0.35 l/min, and Vss = 146 l. In infants who received no sedative, depth of sedation was a function of baseline, postanesthesia effect (Emax model), and circadian night rhythm. In agitated infants, depth of sedation was best described by baseline, postanesthesia effect, and propofol effect (Emax model). The propofol concentration at half maximum effect was 1.76 mg/l (coefficient of variation = 47%) for the COMFORT-Behavior scale and 3.71 mg/l (coefficient of variation = 145%) for the Bispectral Index.

Conclusions

Propofol clearance is two times higher in nonventilated healthy children than reported in the literature for ventilated children and adults. Based on the model, the authors advise a propofol dose of 30 mg/h in a 10-kg infant to achieve values of 12-14 on the COMFORT-Behavior scale and 70-75 on the Bispectral Index during the night. Wide pharmacodynamic variability emphasizes the importance of dose titration.
Evaluation of Patient Simulator Performance as an Adjunct to the Oral Examination for Senior Anesthesia Residents
Authors: Savoldelli Georges L. , Naik Viren N. , Joo Hwan S. , Houston Patricia L. , Graham Marianne , Yee Bevan , Hamstra Stanley J.
Published: February 2006

Background

Patient simulators possess features for performance assessment. However, the concurrent validity and the "added value" of simulator-based examinations over traditional examinations have not been adequately addressed. The current study compared a simulator-based examination with an oral examination for assessing the management skills of senior anesthesia residents.

Methods

Twenty senior anesthesia residents were assessed sequentially in resuscitation and trauma scenarios using two assessment modalities: an oral examination, followed by a simulator-based examination. Two independent examiners scored the performances with a previously validated global rating scale developed by the Anesthesia Oral Examination Board of the Royal College of Physicians and Surgeons of Canada. Different examiners were used to rate the oral and simulation performances.

Results

Interrater reliability was good to excellent across scenarios and modalities: intraclass correlation coefficients ranged from 0.77 to 0.87. The within-scenario between-modality score correlations (concurrent validity) were moderate: r = 0.52 (resuscitation) and r = 0.53 (trauma) (P < 0.05). Forty percent of the average score variance was accounted for by the participants, and 30% was accounted for by the participant-by-modality interaction.

Conclusions

Variance in participant scores suggests that the examination is able to perform as expected in terms of discriminating among test takers. The rather large participant-by-modality interaction, along with the pattern of correlations, suggests that an examinee's performance varies based on the testing modality and a trainee who "knows how" in an oral examination may not necessarily be able to "show how" in a simulation laboratory. Simulation may therefore be considered a useful adjunct to the oral examination.