bluuebunny/crossref_metadata_2025 huggingface dataset:
Electroelastic interaction between a piezoelectric screw dislocation and an elliptical inclusion with interfacial cracks
Authors: Fang Q. H. , Liu Y. W. , Jiang C. P.
Published: September 2005

The electroelastic interaction between a piezoelectric screw dislocation, which is located inside either the inclusion or the matrix, and an elliptical inclusion with interfacial cracks under antiplane mechanical and inplane electrical loads is dealt with. An efficient and concise complex variable method for complex multiply connected region is developed, in terms of which general solutions of complex potentials in the matrix and the inclusion regions are derived. The explicit series‐form solutions are then given for the interface with a finite crack. The image force on the piezoelectric screw dislocation due to the elliptical inclusion, interfacial crack and remote uniform loadings is calculated by using the generalized Peach–Koehler formula. The influence of the curvature and the length of the crack, the shape of the inclusion and electroelastic mismatch between two materials on the image force is evaluated and discussed. Numerical examples show that the elliptical arc interfacial crack has significant effect on the equilibrium position of the dislocation near the interface. Further analysis implies that, when the curvature or the length of the crack goes up to a critical value, existence of the interfacial crack can change the interaction mechanism between a piezoelectric screw dislocation and the elliptical inclusion. In addition, a significative result is that there exists a same value of the crack angle to change the direction of the image force regardless of the shape of the inclusion as the area of the elliptical inclusion taking a constant. The present solutions contain a number of previously known results which can be shown to be special cases. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
lexical vestiges of english in the w$\tilde{e}$ language
Authors: ouafeu yves talla sando
Published: September 2005

this study examines some lexical residues of british colonialism in a language spoken in the western province of cameroon, west africa. the language is w$\tilde{e}$, a dialect within the indigenous language gh[open o]màlà, which is spoken in four villages in the western province of cameroon: bahouan, baham, bayangam and bandjoun. the paper also seeks to answer the question: why are there so many english lexical items in this dialect, changed almost beyond recognition, reminiscent of the presence of the british themselves in cameroon, although this part of the country was formerly under french rule.
‘quality’ problems
Authors: poole brian
Published: September 2005

how the polysemous nature of the word quality can cause problems for readers of articles on quality assurance in higher education. scholarly literature on quality assurance in higher education will always run the risk of confusing or repelling non-specialist readers. that is inevitable since, by its nature, such literature often uses technical jargon in dealing with abstract concepts. yet, a further and more fundamental problem exists, one that may not always be recognized by writers in the field: namely, that the word quality itself has different senses, combines with other words, with unusual semantic effects, and can function both as a noun and an adjective. these factors combine to increase the possibility that general readers may misconstrue key points in texts about quality.
death sentences
Authors: blaisdell bob
Published: September 2005

more tales from a new york writing class. the axe split two ways: half of us against the death penalty, half for it. this i found out by asking the remedial writing-and-reading class to explain on paper how and when they arrived at their current opinion on capital punishment. with most of the students being from overseas, i thought it was important for each to explain his or her culture's or religion's or country's views on the death penalty. then we read – with those opinions and histories staring us in the face – claude gueux.
practising my english in china
Authors: shao x. z.
Published: September 2005

a very personal story. [this ‘language biography’ is written by a younger academic who teaches in a well-known mainland chinese university, who grew up in a time of great difficulty and change, in which he often felt caught between ideologies, cultures, languages, and literatures, in the course of which however english became a deeply personal possession. in order to retain the authentic voice of the text, editorial ‘smoothing out’ has been kept to a minimum. – editor.]
A survey of professionals delivering secondary care regarding their requirements for paediatric cardiac services as provided by specialists
Authors: Maynard Linda , Franklin Rodney C. G. , Wray Jo
Published: September 2005

The provision of outreach services by paediatric cardiac centres enhances the choice for both parents and professionals. We have conducted a survey to investigate the processes for information and communication at times of interface between specialist and local services for cardiac disease. Based on the responses, we suggest that distance from, and level of contact with, the specialist centre may influence satisfaction and the perceived usefulness of more information. We suggest strategies to increase contact, and make more effective targeting of resources.
A comparison of hospital costs with reimbursement received for patients undergoing the Norwood procedure for hypoplasia of the left heart
Authors: Mishra Vinod , Lindberg Harald , Seem Egil , Klokkerud Ingrid , Fredriksen Britt , Skraastad Øyvind , Østlie Anna , Andresen Sølvi , Vaaler Stein
Published: September 2005

Objectives:To determine whether the present system of reimbursement, based on diagnosis-related groups and regular financial budgeting, covers the costs incurred during hospitalisation of 7 children undergoing the three stages of the Norwood sequence for surgical treatment of hypoplastic left heart syndrome.Methods:Between January and September 2003, 7 patients underwent initial surgical palliation with the Norwood procedure at the Rikshospitalet University Hospital. A prospective methodology was developed by our group to measure the costs associated with each individual patient. The patients were closely observed, and the relevant data was collected during their stay in hospital. The stay was divided into four different periods of requirements of resources, defined as heavy intensive care, light intensive care, intermediate care, and ordinary care. At each stage, we recorded the number of staff involved and the duration of surgery and other major procedures, as well as the cost of pharmaceuticals and other consumables. Based on these data, we calculated the cost for each patient. These costs were compared with the corresponding revenue received by the hospital for each of the patients.Results:We found the total mean cost for the three stages of the Norwood sequence was 138,934 American dollars, while the corresponding revenue received by the hospital was 43,735 American dollars. During this period, one patient died during the first stage of the Norwood sequence.Conclusions:Our study shows that steps involved in the Norwood sequence are low-volume but high-cost procedures. The reimbursement received by our hospital for the procedures was less than one-third of the recorded costs.
Markers of endothelial dysfunction and severity of hypoxaemia in the Eisenmenger syndrome
Authors: Soares Rosangela de P. S. , Maeda Nair Y. , Bydlowski Sérgio P. , Lopes Antonio Augusto
Published: September 2005

Endothelial dysfunction has been reported in hypoxaemic patients with the Eisenmenger syndrome, but a direct correlation between levels of endothelial markers and the severity of hypoxaemia has not been explored. With this in mind, we compared the levels in the plasma of tissue-type plasminogen activator, thrombomodulin, and von Willebrand factor in 25 patients with the Eisenmenger syndrome. They had a median age of 31 years, and were divided into 2 groups according to their recent clinical history. Thus, 18 patients were stable, being in functional class II or III, seen as outpatients, and having peripheral saturations of oxygen of 89 plus or minus 5 percent. In contrast, 7 patients were unstable, showing episodes of symptoms placing them in functional class IV, requiring care in hospital, and manifesting saturations of oxygen of 77 plus or minus 5 percent. We were able to follow 12 patients, 8 who were stable and 4 unstable, for 24 months. At baseline, levels of von Willebrand factor were higher in the unstable patients when compared to those who were stable, at 142 plus or minus 29 and 110 plus or minus 25 units per decilitre, respectively (p equal to 0.013). This correlated positively with oxygen desaturation (p less than 0.020). The structural abnormalities also correlated positively with the magnitude of hypoxaemia (p less than 0.020). Levels remained higher in the unstable patients throughout the period of follow-up (p equal to 0.006). Tissue-type plasminogen activator was also increased, at 14.3 plus or minus 8.4 versus 6.5 plus or minus 2.7 nanograms per millilitre in controls (p less than 0.001), whereas thrombomodulin was decreased, with values of 14.4 versus 34.6 nanograms per millilitre in controls (p for median values of less than 0.001). There was no correlation with saturations of oxygen. We conclude that measurement of von Willebrand factor, as compared with tissue-type plasminogen activator and thrombomodulin, will prove a better marker of endothelial response to hypoxaemia in patients with the Eisenmenger syndrome.
Catheter-based closure of a perimembranous ventricular septal defect using the Amplatzer™ occluder in a patient with right-sided heart and mirror-imaged arrangements of all organs
Authors: Bjørnstad Per G. , Smevik Bjarne
Published: September 2005

We describe a 6-year-old boy with a right-sided heart part of the Kartagener syndrome, complicated by presence of a perimembranous ventricular septal defect. The defect was closed interventionally using the Amplatzer™ asymmetrical occluder for ventricular septal defects. The procedure was event-free. Non-operative closure of a ventricular septal defect in this patient demonstrated no other difficulty than mirror-imaged thinking, thus giving evidence that such treatment also can be offered to patients with positional anomalies.
An evidence of beam broadening effect dominating Doppler spectra of field‐aligned irregularities in sporadic E region made with the Chung‐Li radar
Authors: Chu Yen‐Hsyang , Wang Chien‐Ya
Published: September 2005

With the interferometry technique implemented at the 52 MHz Chung‐Li VHF radar, for the first time we present the observational evidence showing that the observed Doppler spectral widths of the field‐aligned irregularities in the sporadic E region may be dominated by the beam broadening effect. Statistics indicates that the ratio of the beam broadening spectral width to the observed Doppler spectral width for the data investigated in this research is in the range 0.1–0.6. In a special case, however, the ratio can be as large as 0.8 or more. After removing the beam broadening spectral width from observed spectral width, we obtain that the magnitude of the spectral width caused by the random fluctuation of the plasma irregularities is in the range 1–7 m/s, comparable to that induced by the neutral turbulences in Es region. We also examine the power law relation σo = aVdb between the observed Doppler spectral width σo and the drift velocity Vd of the irregularities, showing that the estimated b value is only about 0.289, which is much smaller than the value of 4/3 predicted by the theory of nonlinear turbulence energy cascade process. This result is in excellent agreement with that obtained by a stochastic model that simulates the observed Doppler spectral width in terms of the combination of the spectral width caused by neutral‐induced plasma irregularities and the beam broadening spectral width. Therefore it appears very likely that the mechanism involved in the generation of the 3‐m field‐aligned irregularities for the present case seems to be the neutral turbulences that induce the plasma irregularities responsible for the radar returns, instead of the nonlinear turbulence energy cascade process from primary plasma wave associated with the gradient drift instability.
Coronal mass ejections and other extreme characteristics of the 2003 October–November solar eruptions
Authors: Gopalswamy N. , Yashiro S. , Liu Y. , Michalek G. , Vourlidas A. , Kaiser M. L. , Howard R. A.
Published: September 2005

Fast coronal mass ejections (CMEs), X‐class flares, solar energetic particle (SEP) events, and interplanetary shocks were abundantly observed during the episode of intense solar activity in late October and early November 2003. Most of the 80 CMEs originated from three active regions (NOAA ARs 484, 486, and 488). We compare the statistical properties of these CMEs with those of the general population of CMEs observed during cycle 23. We find that (1) the 2003 October–November CMEs were fast and wide on the average and hence were very energetic, (2) nearly 20 percent of the ultrafast CMEs (speed ≥2000 km s−1) of cycle 23 occurred during the October–November interval, including the fastest CME of the study period (∼2700 km s−1 on 4 November 2003 at 1954 UT), (3) the rate of full‐halo CMEs was nearly four times the average rate during cycle 23, (4) at least sixteen shocks were observed near the Sun, while eight of them were intercepted by spacecraft along the Sun‐Earth line, (5) the CMEs were highly geoeffective: the resulting geomagnetic storms were among the most intense of cycle 23, (6) the CMEs were associated with very large SEP events, including the largest event of cycle 23. These extreme properties were commensurate with the size and energy of the associated active regions. This study suggests that the speed of CMEs may not be much higher than ∼3000 km s−1, consistent with the free energy available in active regions. An important practical implication of such a speed limit is that the Sun‐Earth travel times of CME‐driven shocks may not be less than ∼0.5 day. Two of the shocks arrived at Earth in <24 hours, the first events in ∼30 years and only the 14th and 15th documented cases of such events since 1859.
Fraction of photosynthetically active radiation absorbed by Amazon tropical forest: A comparison of field measurements, modeling, and remote sensing
Authors: Senna Mônica C. A. , Costa Marcos H. , Shimabukuro Yosio E.
Published: September 2005

The fraction of absorbed photosynthetically active radiation (FAPAR) is a vegetation biophysical variable that characterizes energy, mass, and momentum exchanges and is used extensively in models that represent the transfer of energy, carbon, water, and the biogeochemistry of terrestrial ecosystems. This paper compares three estimates of FAPAR by an Amazonian tropical rain forest. In the Tapajós National Forest, near Santarém, state of Pará, Brazil, FAPAR is estimated based on field measurements, modeling (using IBIS which simulates the fluxes in the soil‐vegetation‐atmosphere system considering two vegetation layers) and remotely sensed Moderate Resolution Imaging Spectroradiometer (MODIS) monthly FAPAR product, which has not been validated for a tropical rain forest yet. FAPAR based on field observations is calculated from incoming and reflected PAR measurements taken above the canopy, and downward PAR at a 15 m height, corrected to be representative of the entire canopy, obtaining an annual mean value of 0.91. FAPAR simulated by the Integrated Biosphere Simulator (IBIS) is 0.76, while the annual average FAPAR estimated by MODIS is 0.85. If we consider that MODIS estimates include only PAR absorbed by leaves, the remote sensing estimates are very close to field measurements corrected to include only the absorption by leaves (0.87); hence we conclude that the MODIS FAPAR product for the tropical rain forest is reliable to be used in future studies. However, model estimates of FAPAR for the tropical forest are low, and adjustments on the algorithm used to calculate the absorbed radiation by the canopy are necessary.
Time reversal of electromagnetic waves and telecommunication
Authors: Lerosey G. , de Rosny J. , Tourin A. , Derode A. , Montaldo G. , Fink M.
Published: September 2005

Time reversal (TR) communication in various configurations (single input, single output (SISO); multiple inputs, single output (MISO); or multiple inputs, multiple outputs (MIMO)) is studied. In particular, we report an experimental demonstration of time reversal focusing with electromagnetic waves in a SISO scheme. An antenna transmits a 1 μs electromagnetic pulse at a central frequency of 2.45 GHz in a high‐Q cavity. Another antenna records the strongly reverberated signal. The time‐reversed wave is built and transmitted back by the same antenna acting now as a time reversal mirror. The wave is found to converge to its initial source and is compressed in time. The quality of focusing is determined by the frequency bandwidth and the spectral correlations of the field within the cavity. A spatial focusing of the compressed pulse is also shown. This experiment is the first step for a communication scheme based on time reversal. It would be very interesting for ultrawideband communication in complex media since TR would permit compensation for delay spreading. MISO and MIMO TR communications are discussed on the basis of small‐scale experiments with ultrasound. In particular, the binary error rate of the method is studied as a function of both data rate and external noise. A simple theoretical approach explains the results.
A study on the peak Dst and peak negative Bz relationship during intense geomagnetic storms
Authors: Gonzalez W. D. , Echer E.
Published: September 2005

This paper is a study of the relationship between the geomagnetic storm index Dst and the southward component, Bs, of the interplanetary magnetic field (IMF) driver. This study was performed during the ACE observational period (1997–2002), for which 64 intense geomagnetic storms (Dst ≤ −85 nT) were analyzed. After taking into account the propagation time between the L1 point and Earth (∼1 h) and the magnetosphere/ring current response‐time to solar wind forcing (∼1 h), it was determined that the average delay between the peak Bs and the peak Dst values is ∼2 h. It was also observed that the Bs value at peak Dst is ∼75% of the peak Bs value in the entire event. When these results are analyzed in terms of the interplanetary electric field, associated with Bz, some interesting additional studies are indicated, for which some simple results, of practical space weather forecasting use, are anticipated.
Path integral methods for rotating molecules in superfluids
Authors: Zillich R. E. , Paesani F. , Kwon Y. , Whaley K. B.
Published: September 2005

We present a path integral Monte Carlo (PIMC) methodology for quantum simulation of molecular rotations in superfluid environments such as helium and para-hydrogen that combines the sampling of rotational degrees of freedom for a molecular impurity with multilevel Metropolis sampling of Bose permutation exchanges for the solvating species. We show how the present methodology can be applied to the evaluation of imaginary time rotational correlation functions of the molecular impurity, from which the effective rotational constants can be extracted. The combined rotation/permutation sampling approach allows for the first time explicit assessment of the effect of Bose permutations on molecular rotation dynamics, and the converse, i.e., the effect of molecular rotations on permutation exchanges and local superfluidity. We present detailed studies showing that the effect of Bose permutations in the solvating environment is more significant for the dynamics of heavy than light molecules in helium, and that Bose permutation exchanges are slightly enhanced locally by molecular rotation. Finally, the examples studied here reveal a size dependence of rotational excitations for molecules possessing a strongly anisotropic interaction with helium in HeN4 clusters between N∼20 and N∼103.
Voronoi cell volume distribution and configurational entropy of hard-spheres
Authors: Senthil Kumar V. , Kumaran V.
Published: September 2005

The Voronoi cell volume distributions for hard-disk and hard-sphere fluids have been studied. The distribution of the Voronoi free volume υf, which is the difference between the actual cell volume and the minimal cell volume at close packing, is well described by a two-parameter (2Γ) or a three-parameter (3Γ) gamma distribution. The free parameter m in both the 2Γ and 3Γ models is identified as the “regularity factor.” The regularity factor is the ratio of the square of the mean and the variance of the free volume distribution, and it increases as the cell volume distribution becomes narrower. For the thermodynamic structures, the regularity factor increases with increasing density and it increases sharply across the freezing transition, in response to the onset of order. The regularity factor also distinguishes between the dense thermodynamic structures and the dense random or quenched structures. The maximum information entropy (max-ent) formalism, when applied to the gamma distributions, shows that structures of maximum information entropy have an exponential distribution of υf. Simulations carried out using a swelling algorithm indicate that the dense random-packed states approach the distribution predicted by the max-ent formalism, though the limiting case could not be realized in simulations due to the structural inhomogeneities introduced by the dense random-packing algorithm. Using the gamma representations of the cell volume distribution, we check the numerical validity of the Cohen-Grest expression [M. H. Cohen and G. S. Grest, Phys. Rev. B 20, 1077 (1979)] for the cellular (free volume) entropy, which is a part of the configurational entropy. The expression is exact for the hard-rod system, and a correction factor equal to the dimension of the system, D, is found necessary for the hard-disk and hard-sphere systems. Thus, for the hard-disk and hard-sphere systems, the present analysis establishes a relationship between the precisely defined Voronoi free volume (information) entropy and the thermodynamic entropy. This analysis also shows that the max-ent formalism, when applied to the free volume entropy, predicts an exponential distribution which is approached by disordered states generated by a swelling algorithm in the dense random-packing limit.
Gold cluster formation on a fullerene surface
Authors: Kröger H. , Reinke P. , Büttner M. , Oelhafen P.
Published: September 2005

The growth of Au clusters on a fullerene thin film was investigated by in situ photoelectron spectroscopy in the ultraviolet (UPS) and x-ray (XPS) regime. Due to its highly corrugated surface fullerene films provide a wide range of bonding sites which could be exploited as molecular templates and serve to create a cluster superstructure. To gain insight into the fullerene-Au interaction two types of experiments were performed: (i) the deposition of Au on a fullerene surface, and (ii) the deposition of fullerenes on a Au surface. In both experiments an island growth mode is observed. The deposition of submonolayer amounts of C60 onto a gold film showed that the main interaction of the two species is due to chemisorption of the first C60 monolayer. In addition a constant band bending in the fullerene film is detected, but the UPS valence-band spectra show that there is no charge transfer from the Au to the C60 lowest unoccupied molecular orbital. In the reverse experiment, the cluster growth of Au on the corrugated C60 surface, the analysis of the Au core level does not reveal a specific bonding or nucleation site for Au atoms and clusters. This is in contrast to observations with Si clusters, which prefer to reside in the troughs between the fullerene molecules. The Au clusters grow continually from a size of about 55 atoms for the early stages of growth up to 150 atoms for the deposition of a nominal coverage of 1.5 nm. These data are derived from an analysis of the d-band splitting and the Au 4f core-level shift due to delayed photohole relaxation. The thermal stability of the Au-clusters-covered fullerene film was investigated by annealing in situ up to temperatures of 650 °C. For temperatures up to 450 °C a continuous growth of the clusters is detected, which is accompanied by a slight drop in Au concentration in the range of XPS for annealing temperatures higher than 350 °C. This may be due to a ripening of the clusters. The presence of Au apparently delays fullerene sublimation. The film shows a very good thermal stability and even after annealing at 650 °C there is still a fullerene film detectable in the photoelectron spectroscopy spectra.
Electron attachment and detachment, and the electron affinities of C5F5N and C5HF4N
Authors: Van Doren Jane M. , Kerr Donna M. , Miller Thomas M. , Viggiano A. A.
Published: September 2005

Rate constants have been measured for electron attachment to C5F5N (297–433K) and to 2,3,5,6-C5HF4N (303K) using a flowing-afterglow Langmuir-probe apparatus (at a He gas pressure of 133Pa). In both cases only the parent anion was formed in the attachment process. The attachment rate constants measured at room temperature are 1.8±0.5×10−7 and 7±3×10−10cm−3s−1, respectively. Rate constants were also measured for thermal electron detachment from the parent anions of these molecules. For C5F5N− detachment is negligible at room temperature, but increases to 2530±890s−1 at 433K. For 2,3,5,6-C5HF4N−, the detachment rate at 303K was 520±180s−1. The attachment/detachment equilibrium yielded experimental electron affinities EA(C5F5N)=0.70±0.05eV and EA(2,3,5,6-C5HF4N)=0.40±0.08eV. Electronic structure calculations were carried out for these molecules and related C5HxF5−xN using density-functional theory and the G3(MP2)‖B3LYP compound method. The EAs are found to decrease by 0.25eV, on average, with each F substitution by H. The calculated EAs are in good agreement with the present experimental results.
Modeling solvent effects on electron-spin-resonance hyperfine couplings by frozen-density embedding
Authors: Neugebauer Johannes , Louwerse Manuel J. , Belanzoni Paola , Wesolowski Tomasz A. , Baerends Evert Jan
Published: September 2005

In this study, we investigate the performance of the frozen-density embedding scheme within density-functional theory [J. Phys. Chem. 97, 8050 (1993)] to model the solvent effects on the electron-spin-resonance hyperfine coupling constants (hfcc’s) of the H2NO molecule. The hfcc’s for this molecule depend critically on the out-of-plane bending angle of the NO bond from the molecular plane. Therefore, solvent effects can have an influence on both the electronic structure for a given configuration of solute and solvent molecules and on the probability for different solute (plus solvent) structures compared to the gas phase. For an accurate modeling of dynamic effects in solution, we employ the Car-Parrinello molecular-dynamics (CPMD) approach. A first-principles-based Monte Carlo scheme is used for the gas-phase simulation, in order to avoid problems in the thermal equilibration for this small molecule. Calculations of small H2NO-water clusters show that microsolvation effects of water molecules due to hydrogen bonding can be reproduced by frozen-density embedding calculations. Even simple sum-of-molecular-densities approaches for the frozen density lead to good results. This allows us to include also bulk solvent effects by performing frozen-density calculations with many explicit water molecules for snapshots from the CPMD simulation. The electronic effect of the solvent at a given structure is reproduced by the frozen-density embedding. Dynamic structural effects in solution are found to be similar to the gas phase. But the small differences in the average structures still induce significant changes in the computed shifts due to the strong dependence of the hyperfine coupling constants on the out-of-plane bending angle.
Heat pulse propagation across the rational surface in a large helical device plasma with counter-neutral beam injection
Authors: Yakovlev M. , Inagaki S. , Shimozuma T. , Kubo S. , Morisaki T. , Nagayama Y. , Kawahata K. , Komori A. ,   LHD Experimental Group
Published: September 2005

Core electron temperature profile flattening is observed in a large helical device [A. Iiyoshi et al. Nucl. Fusion 39, 1245 (1999)] inward shifted plasma with counter-neutral beam injection. To study this phenomenon, heat pulse experiments are performed by on-axis electron cyclotron heating power modulation. A unique feature of heat pulse propagation is observed near the m∕n=2∕1 rational surface (m, n are the poloidal and toroidal mode numbers, respectively). A simultaneous response of the temperature perturbation on radially separated flux surfaces is shown. The change in the magnetic field topology due to the presence of a magnetic island structure can explain this nonmonotonic heat pulse propagation. The estimated O-point position of the island is located near the m∕n=2∕1 rational surface.
Excitation of internal kink mode by barely trapped suprathermal electrons
Authors: Sun Youwen , Wan Baonian , Wang Shaojie , Zhou Deng , Hu Liqun , Shen Biao
Published: September 2005

The barely trapped suprathermal electrons can destabilize the internal kink mode when their density gradient is positive within the rational surface and the beta value of the suprathermal electrons exceeds a threshold value. With the assumption of two different models of energy distribution of the suprathermal electrons, the threshold beta value of the barely trapped suprathermal electrons, the real frequency, and the growth rate of the internal kink mode are found in this paper. The results are in reasonable agreement with the recent experimental observations on DIII-D tokamak [K. L. Wong, M. S. Chu, T. C. Luce et al., Phys. Rev. Lett. 85, 996 (2000)].
Self-similar turbulence evolution and the dissipation rate transport equation
Authors: Rubinstein Robert , Clark Timothy T.
Published: September 2005

The dissipation rate transport equation is analyzed in the setting of time-dependent isotropic turbulence driven by a statistically unsteady force. In the limit of slow spectral variation, the balance between vortex stretching and enstrophy destruction postulated by Tennekes and Lumley [A First Course in Turbulence (MIT Press, Cambridge, MA, 1972)] is verified and spectral closure is used to identify the O(Re0) difference between them; however, no definite formulation of an ϵ-equation results. The ϵ equation is usually calibrated to predict self-similar unit flows such as decaying turbulence and homogeneous shear flow. The limitations of this approach are shown by constructing classes of self-similar states of forced isotropic turbulence. Any choice of constants in the ϵ equation yields a model that is consistent with some self-similar states, but not with all possible states: two-equation models of the standard form select a class of admissible self-similar states and rule out the others.
Electron paramagnetic resonance field-modulation eddy-current analysis of silver-plated graphite resonators
Authors: Mett Richard R. , Anderson James R. , Sidabras Jason W. , Hyde James S.
Published: September 2005

Magnetic field modulation is often introduced into a cylindrical TE011 electron paramagnetic resonance (EPR) cavity through silver plating over a nonconductive substrate. The plating thickness must be many times the skin depth of the rf and smaller than the skin depth of the modulation. We derive a parameter that quantifies the modulation field penetration and find that it also depends on resonator dimensions. Design criteria based on this parameter are presented graphically. This parameter is then used to predict the behavior of eddy currents in substrates of moderate conductivity, such as graphite. The conductivity of the graphite permits improved plating uniformity and permits use of electric discharge machining (EDM) techniques to make the resonator. EDM offers precision tolerances of 0.005 mm and is suitable for small, complicated shapes that are difficult to machine by other methods. Analytic predictions of the modulation penetration are compared with the results of finite-element simulations. Simulated magnetic field modulation uniformity and penetration are shown for several elemental coils and structures including the plated graphite TE011 cavity. Fabrication and experimental testing of the structure are discussed. Spatial inhomogeneity of the modulation phase is also investigated by computer simulation. We find that the modulation phase is uniform to within 1% over the TE011 cavity. Structures of lower symmetry have increased phase nonuniformity.
The ultrasonic/shear-force microscope: Integrating ultrasonic sensing into a near-field scanning optical microscope
Authors: La Rosa A. , Cui X. , McCollum J. , Li N. , Nordstrom R.
Published: September 2005

An ultrasonic transducer is incorporated into a near-field scanning optical microscope (NSOM) to augment its versatility to characterize the properties of layers adsorbed to a sample’s surface. Working under typical NSOM operation conditions, the ultrasonic transducer—attached underneath the sample—demonstrates sufficient sensitivity to monitor the waves generated by the tapered NSOM probe that oscillates in the proximity of, and parallel to, the sample’s top surface. This capability makes the newly integrated ultrasonic/shear-force microscope a valuable diagnostic tool in the study of sliding friction and surface phenomena in general. Here, it is used to concurrently and independently monitor the effects that probe-sample interactions exert on the probe (that is attached to a piezoelectric tuning fork) and on the sample (that is attached to the ultrasonic transducer). The signal from the tuning fork (TF) constitutes the so called “shear-force” signal, widely used in NSOM as a feedback to control the probe’s vertical position but whose working mechanism is not yet well understood. Tests involving repeated vertical z motion of the probe towards and away from the sample’s surface reveal that the TF and ultrasonic (US) signals have distinct z dependence. Additionally, where the TF signal showed abrupt changes during the approach, the US changed accordingly. A shift in the probe’s resonance frequency that depends on the probe-sample distance is also observed through both the TF and the US responses. Within the sensitivity of the apparatus, ultrasonic signals were detected only at probe-sample distances where the probe’s resonance frequency had shifted significantly. These measured signals are consistent with a probe entering and leaving a viscoelastic fluid-like film above the sample. The film acts as the medium where waves are generated and coupled to the ultrasonic sensor located beneath the sample. To our knowledge, this is the first reported use of ultrasonic detection for detailed monitoring of the distance dependence of probe-sample interactions, and provides direct evidence of sound as an energy dissipation channel in wear-free friction. This newly integrated ultrasonic/shear-force microscope, which can be implemented with any functionalized proximal probe (including aperture and apertureless NSOM), can become a valuable metrology tool in surface science and technology.
Aspect ratio dependence of electromechanical coupling coefficient of piezoelectric resonators
Authors: Kim Moojoon , Kim Jungsoon , Cao Wenwu
Published: September 2005

The most important parameter characterizing a piezoelectric material is the electromechanical coupling coefficient, which specifies the conversion efficiency between electrical and mechanical energies for a given vibration mode. For the resonance along the poling direction, there are two coupling coefficients defined, i.e., kt and k33, which are for resonators of the same mode but two extreme aspect ratios and they differ substantially. We have derived a unified formula for this coupling coefficient as a function of the vibrator aspect ratio. The unified formula can provide more accurate description to the effective coupling coefficient of resonators not satisfying the extreme aspect ratio requirements.
Relaxation of compressively-strained AlGaN by inclined threading dislocations
Authors: Follstaedt D. M. , Lee S. R. , Provencio P. P. , Allerman A. A. , Floro J. A. , Crawford M. H.
Published: September 2005

Transmission electron microscopy and x-ray diffraction were used to assess the microstructure and strain of AlxGa1−xN(x=0.61–0.64) layers grown on AlN. The compressively-strained AlGaN is partially relaxed by inclined threading dislocations, similar to observations on Si-doped AlGaN by P. Cantu, F. Wu, P. Waltereit, S. Keller, A. E. Romanov, U. K. Mishra, S. P. DenBaars, and J. S. Speck [Appl. Phys. Lett. 83, 674 (2003)]; however, in our material, the dislocations bend before the introduction of any Si. The bending may be initiated by the greater lattice mismatch or the lower dislocation density of our material, but the presence of Si is not necessarily required. The relaxation by inclined dislocations is quantitatively accounted for with the model of A. E. Romanov and J. S. Speck [Appl. Phys. Lett. 83, 2569 (2003)], and we demonstrate the predicted linear dependence of relaxation on layer thickness. Notably, such relaxation was not found in tensile strained AlGaN grown on GaN [J. A. Floro, D. M. Follstaedt, P. Provencio, S. J. Hearne, and S. R. Lee, J. Appl. Phys. 96, 7087 (2004)], even though the same mechanism appears applicable.
Effect of food intake on hind-limb and whole-body protein metabolism in young growing sheep: chronic studies based on arterio-venous techniques
Authors: Harris Patricia M. , Skene Pat A. , Buchan Vivien , Milne E. , Calder A. G. , Anderson Susan E. , Connell Alexmary , Lobley G. E.
Published: September 2005

Whole-body protein synthesis, estimated by the irreversible loss rate procedure, and hind-leg protein metabolism determined by arterio-venous techniques were monitored in response to three nutritional conditions (approximately 0.6, 12 and 1.8 x energy maintenance (M)) in ten wether lambs (33 kg average live weight). In all lambs and treatments measurements were based on radiolabelled phenylalanine, but the terminal procedures (five at 0.6 x M and five at 1.8 x M) also included infusion of [1-13C]leucine; this permitted comparison of amino acids catabolized (leucine) and non-metabolized (phenylalanine) by the hind-limb tissues. Whole-body protein synthesis increased with intake and the relationship with energy expenditure was slightly lower than that reported previously for pigs and cattle. The efficiency of protein retention: protein synthesis did not exceed 0.25 between the two intake extremes. Effects of intake on amino acid oxidation were similar to those observed for cattle. Hind-limb protein synthesis also increased significantly (P < 0.001) in response to intake. Estimates of protein gain, from net uptake values, indicated that the tissues made a greater proportional contribution to total protein retention above M and to protein loss below M, emphasizing the role played by muscle tissue in providing mobile protein stores. The rates of protein synthesis calculated depended on the selection of precursor (blood) metabolite, but rates based on leucine always exceeded those based on phenylalanine when precursor from the same pool was selected. The incremental efficiency of protein retained: protein synthesis was apparently unity between 0.6 and 1.2 x M but 0.3 from 1.2 to 1.8 x M. Blood flow through the iliac artery was also proportional to intake. Leucine and oxo-acid catabolism to carbon dioxide increased with intake such that the metabolic fate of the amino acid was distributed in the proportion 2:1 between protein gain and oxidation. The rates of oxidation were only 1–3% the reported capacity of the rate-limiting dehydrogenase enzyme in muscle, but sufficient enzyme activity resides in the hind-limb adipose tissue to account for such catabolism
Comparison of the effects of cassava (Manihot esculenta Crantz) organic cyanide and inorganic cyanide on muscle and bone development in a Nigerian breed of dog
Authors: Ibebunjo C. , Kamalu Beryl P. , Ihemelandu E. C.
Published: September 2005

Effects of cassava (Manihot esculenta Crantz)-borne organic cyanide and inorganic cyanide in the form of sodium cyanide on bone and muscle development were investigated in eighteen dogs of Nigerian breed. After 16 weeks of stabilization in the laboratory from the time of purchase when the dogs were fed on the same diet, they were randomly assigned to three experimental groups of six dogs each. The control group was fed on rice while the other two groups were fed on either cassava (gari) or rice plus cyanide. The three diets were made isoenergetic and isonitrogenous by varying the quantity of meat incorporated into them. The results obtained after 14 weeks of feeding the respective diets indicated that there was retardation of muscle development in the gari-fed dogs. This may have resulted from gluconeogenesis from muscle protein associated with suppression of production of insulin by the pancreas in this group. The results indicated also that the effects of inorganic dietary cyanides on muscle development were different. Both forms of dietary cyanides, however, had no adverse effect on bone development
Avian community composition in isolated forest fragments: a conceptual revision
Authors: Brown William P. , Sullivan Patrick J.
Published: September 2005

Forest birds do not respond equally to effects of deforestation: some species are absent from small fragments, some species increase in relative abundance in isolated fragments, while others are not present in fragments that appear to be of sufficient quality and area to meet their ecological requirements. Mechanisms currently associated with forest fragmentation are insufficient to predict how populations of individual species respond to deforestation. Based on published data representing 573 forest fragments, we examined the effects of deforestation on the relative abundance of birds in isolated forest fragments. We tested the prediction that species exhibit differential responses to deforestation based on their mean body mass. We found that forest bird communities in small, isolated forests can be generally predicted based on the home range needs and the average mass of individual bird species; mass may be an indicator of competitive abilities. Large and small species are not present and medium‐sized species may increase in relative abundance in these forests. The limitations and implications of this pattern are discussed.
Spatial decomposition of predation risk using resource selection functions: an example in a wolf–elk predator–prey system
Authors: Hebblewhite M. , Merrill E. H. , McDonald T. L.
Published: September 2005

Predation is a fundamental ecological and evolutionary process that varies in space, and the avoidance of predation risk is of central importance in foraging theory. While there has been a recent growth of approaches to spatially model predation risk, these approaches lack an adequate mechanistic framework that can be applied to real landscapes. In this paper we show how predation risk can be decomposed into encounter and attack stages, and modeled spatially using resource selection functions (RSF) and resource selection probability functions (RSPF). We use this approach to compare the effects of landscape attributes on the relative probability of encounter, the conditional probability of death given encounter, and overall wolf and elk resource selection to test whether predation risk is simply equivalent to location of the predator. We then combine the probability of encounter and conditional probability of death into a spatially explicit function of predation risk following Lima and Dill's reformulation of Holling's functional response. We illustrate this approach in a wolf–elk system in and adjacent to Banff National Park, Alberta, Canada. In this system we found that the odds of elk being encountered by wolves was 1.3 times higher in pine forest and 4.1 times less in grasslands than other habitats. The relative odds of being killed in pine forests, given an encounter, increased by 1.2. Other habitats, such as grasslands, afforded elk reduced odds (4.1 times less) of being encountered and subsequently killed (1.4 times less) by wolves. Our approach illustrates that predation risk is not necessarily equivalent to just where predators are found. We show that landscape attributes can render prey more or less susceptible to predation and effects of landscape features can differ between the encounter and attack stages of predation. We conclude by suggesting applications of our approach to model predator–prey dynamics using spatial predation risk functions in theoretical and applied settings.
The influence of endurance and resistance exercise on muscle capillarization in the elderly: a review
Authors: Harris B. A.
Published: September 2005

Aim:  Ageing is one of many factors altering skeletal muscle. Conflicting results from previous studies guided this review to identify what has been found to date regarding microvascular adaptations in skeletal muscle as the result of ageing or inactivity, and endurance or resistance training interventions. Additionally, this review attempts to identify the variety of parameters for determining capillarization and discuss why these might be contributing to the conflicting results.

Methods:  Electronic database searches were conducted for full‐length articles using relevant keywords related to ageing, muscle capillarization and exercise in all fields. Cross‐sectional, longitudinal, training and review papers were included. Several studies on younger subject adaptation were also included for comparison.

Results:  Ageing and inactivity both result in regressive structural and functional changes to skeletal muscle capillarization. The rate and magnitude of decline is still unknown. Endurance training can positively effect structural changes to capillarity. There is conflicting evidence regarding the effects of resistance training. Training intensity may be an important factor. Biopsy sampling, histological staining and several measurement protocols may be providing inaccurate estimations of capillarity.

Conclusion:  Part of the difficulty in determining the nature of these relationships has been the inconsistency in research conducted regarding age groups and controlling for past and present activity patterns. Further difficulties comparing across studies arise due to the variety of methods and parameters used to sample and analyse muscle tissue. Standardizing methodology will allow future research to yield more consistent results.
Use of remifentanil for tracheal intubation for caesarean section in a patient with suxamethonium apnoea
Authors: Alexander R. , Fardell S.
Published: September 2005

A parturient presented for elective caesarean section with a history of multiple spinal operations and scoliosis and a biochemical diagnosis of suxamethonium apnoea. She declined any attempt at regional anaesthesia. We describe the use of a thiopental/remifentanil technique to relax the larynx and provide rapid and excellent conditions for laryngoscopy and tracheal intubation. The parturient awoke following an uneventful caesarean section with excellent pain relief and no recall. The baby had normal Apgar scores and umbilical blood gas measurements.